Dissertations / Theses: 'Seismic techniques'

1

Fisher, R. "A downhole electrolytic seismic source." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Bouvier, Charlotte A. (Charlotte Aude Caroline) 1980. "Techniques of seismic retrofitting for concrete structures." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29327.

Full text

Abstract:

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.
Includes bibliographical references (p. 59-62).
Recent earthquakes, starting with the 1971 San Fernando Earthquake in California, left major destructions, damaged the infrastructure, and raised questions about the vulnerability and design practice of structures, especially concrete structures. Design codes have being updated to include seismic previsions but structures build before 1971 have to be retrofitted. The focus of this paper is concrete structures. Surveys done after earthquakes have shown that the major problem with concrete structures is columns. Pre- 1971 detailing left column with lack of confinement as well as lap-slice in plastic hinge regions creating potential failures in flexure strength and/or ductility, and in shear. Other critical structural elements include, but are not limited to, gravity design frames, footings, shear walls, connections, and beams. There are two major categories of retrofit options for concrete structure; local and global methods. Local methods focus at the element level on a particular member that is deficient and in improving it to perform better. Those methods include adding concrete, steel, or composite to the outside of the member. All three methods are effective but each present some disadvantages: concrete is labor intensive, steel requires heavy construction equipments, and composites have high initial cost. Global methods concentrate at the structure level and retrofit to obtain a better overall behavior of the entire structure. The different global techniques are addition of shear walls or steel bracings, and base isolation. All three methods are effective. Shear walls are usually an expensive solution but they are flexible in their distribution allowing them to be hidden in the architecture. Steel bracings allow for openings but their connections to the existing structure can be problematic. Finally, base isolation is an option that is becoming increasingly popular and that provides good behavior in earthquake for low to mid high structures. The different systems presented all have some advantages and disadvantages and the option chosen for the retrofit depends on the existing structure requirement. The different system presented can be combined to provide more efficient and more flexible retrofit schemes.
by Charlotte A.C. Bouvier.
M.Eng.

APA, Harvard, Vancouver, ISO, and other styles

3

Masoomzadeh, Hassan. "Processing techniques for wide-angle seismic data." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613894.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Jarvis, Kevin Donald Gibson. "The application of seismic techniques to hydrogeological investigations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ61119.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

SZCZERBACKI, RICARDO. "USING POINT BASED TECHNIQUES FOR SEISMIC HORIZONS VISUALIZATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=14015@1.

Full text

Abstract:

A visualização de horizontes sísmicos constitui uma importante área de conhecimento amplamente aplicada na prospecção de hidrocarbonetos pela indústria do petróleo. Diferentes técnicas são atualmente empregadas na apresentação destas superfícies, sendo usualmente utilizadas as soluções baseadas na geração de malhas poligonais, que se beneficiam da otimização das placas gráficas atuais no desenho de triiângulos. Este trabalho faz uma avaliação do uso da renderização baseada em pontos, no lugar de polígonos, para a visualização de horizontes sísmicos. Para isso as técnicas de cada etapa do processo são avaliadas, levando-se em conta a natureza específica dos dados de interpretação de horizontes em volumes sísmicos e o resultado final esperado para a visualização deste tipo de dados. O algoritmo utilizado baseia-se no método conhecido como Surface Splatting para a renderização dos pontos originais, sendo estudados a estruturação apropriada para os dados a serem visualizados, a técnica para obtenção de normais, a abordagem adequada para o cálculo da iluminação e mecanismos adicionais necessários ao processo. Resultados da aplicação do método em dados reais são, ao final do trabalho, analisados e comparados à renderização tradicional para os horizontes avaliados.
Seismic horizon visualization stands as an important knowledge area used to support exploration on the oil industry. Different techniques currently employed to render this kind of surfaces are usually based on polygonal meshes generation, which benefits from graphics boards optimization on drawing triangles. This work is an evaluation of Point Based rendering techniques to replace polygonal approaches in seismic horizons visualization. To do so, this study revisits each stage of the seismic visualization process. The algorithm adopted here is based on the Surface Splatting with the EWA filter. This work also presents a study on normal evaluation and data structures to store points and normal. Special care is taken in shading techniques. The implementation yielded results that are used to support the evaluation of the Point Based Techniques on real 3D Seismic data. Traditional triangle based rendering is also presented to compare results.

APA, Harvard, Vancouver, ISO, and other styles

6

Norville, Pelham D. "Time-Reversal Techniques in Seismic Detection of Buried Objects." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14475.

Full text

Abstract:

An investigation is presented of the behavior of time-reversal focusing in soils. Initial numerical models demonstrate time-reversal focusing to be effective in elastic media, including when a large number of scattering objects were present in the medium. When scattering objects are present, time-reversal focusing demonstrates superior focusing ability when compared to other excitation methods such as uniform excitation or time-delay focusing. Multiple experimental investigations of experimental time-reversal focusing performed in sand evaluate time-reversal focusing effectiveness when multiple near-surface scattering objects are present in the medium. Experimental results demonstrate that time-reversal focusing is effective in the experimental context as well as the numerical models. Further experiments examine time-reversal focusing in more extreme cases where the entire ballistic wave is blocked, and the only energy reaching the focus point is reflected from scattering objects in the medium. A comparison to other focusing methods demonstrates that under these conditions, most focusing attempts with traditional methods will fail completely while time-reversal focusing does not. Additional configurations of time-reversal focusing examine its effectiveness when scattering is caused by an asymmetrical surface layers. The impact of an asymmetrical or non-uniform excitation array is also examined for time-reversal focusing in the presence of scattering objects. An investigation of the effects of scattering object geometry on focusing resolution in time-reversal focusing is also presented. Scattering object field density is found to have a strong, but diminishing effect on focusing resolution as the scattering object field density increased. Loss of surface wave energy available for focusing due to mode-conversion is found to be correlated with the density of the scattering object field. The impact of the weak non-linear nature of the soil on time-reversal focusing is examined through a study of time-reversal focusing behavior for a variety of amplitudes that generate different levels of non-linearity in the soil. This study of nonlinearity is coupled with a study of the impact of noise on time-reversal focusing. It appears that both non-linearity and noise have an impact on time-reversal focusing effectiveness. Further, the loss from these mechanisms seems to be interrelated. Noise seems to enhance non-linear loss in the soil.

APA, Harvard, Vancouver, ISO, and other styles

7

Brazier, Richard Anthony 1967. "Seismic wave propagation stitching: Matching local and global techniques." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282549.

Full text

Abstract:

Multiple methods exist for modeling with synthetic seismograms, each with its own characteristic application; local and detailed; global and asymptotic; body and/or surface waves. Events such as the nuclear tests in the Tarim Basin in China, recorded at regional distances require more than one such characteristic. A successful model would need detail close in and a global result. The ability to join two methods can therefore be very powerful. Within this text the exploration is of finite difference and discrete wavenumber integration methods. The basis of the conversion between methods is the idea in Huygen's principle of representing a wave front as multiple sources, then propagated as an alternate method. Modeling detail locally, finite difference eventually becomes computationally intensive or undetailed. Representation theory replaces finite difference with discrete wavenumber integration propagating to the receiver at a regional distance. The requirement for multiple sources means that efficiency and optimization of methods are paramount.

APA, Harvard, Vancouver, ISO, and other styles

8

Tu, Peter Henry. "Extracting and analysing seismic events using computer vision techniques." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282329.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Parsons, Adrian. "Seismic exploration techniques applied to ultrasonic imaging within concrete." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368818.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Taylor, Simon H. "Techniques and advantages of kriging seismic time and velocity data /." Title page, table of contents and abstract only, 1986. http://web4.library.adelaide.edu.au/theses/09SB/09sbt246.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Howard, Wheeler B. "Delineation of excessive strength soils through acoustic to seismic techniques /." Full text available from ProQuest UM Digital Dissertations, 2007. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=0&did=1409498351&SrchMode=1&sid=3&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1220900043&clientId=22256.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Civjan, Scott Adam. "Investigation of retrofit techniques for seismic resistant steel moment connections /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Leggett, Miles. "Crosshole seismic processing of physical model and coal measures data." Thesis, Durham University, 1992. http://etheses.dur.ac.uk/5623/.

Full text

Abstract:

Crosshole seismic techniques can be used to gain a large amount of information about the properties of the rock mass between two or more boreholes. The bulk of this thesis is concerned with two crosshole seismic processing techniques and their application to real data. The first part of this thesis describes the application of traveltime and amplitude tomographic processing in the monitoring of a simulated EOR project. Two physical models were made, designed to simulate 'pre-flood' and 'post-flood' stages in an EOR project. The results of the tomography work indicate that it is beneficial to perform amplitude tomographic processing of cross-well data, as a complement to traveltime inversion, because of the different response of velocity and absorption to changes in liquid/gas saturations for real reservoir rocks. The velocity tomograms image the flood zone quite accurately. Amplitude tomography shows the flood zone as an area of higher absorption but does not image its boundaries as precisely, because multi-pathing and diffraction effects are not accounted for by the ray-based techniques used. Part two is concerned with the crosshole seismic reflection technique, using data acquired from a site in northern England. The processing of these data is complex and includes deconvolution, wavefield separation and migration to a depth section. The two surveys fail to pin-point accurately the position of a large fault; the disappointing results, compared to earlier work in Yorkshire, are attributed to poorer generation of compressional body waves in harder Coal Measures strata. The final part of this thesis describes the results from a pilot seismic reflection test over the Tertiary igneous centre on the Isle of Skye, Scotland. The results indicate that the base of a large granite body consists of interlayered granites and basic rocks between 2.1 and 2.4km below mean sea level.

APA, Harvard, Vancouver, ISO, and other styles

14

Ismail, Najif. "Selected strengthening techniques for the seismic retrofit of unreinforced masonry buildings." Thesis, University of Auckland, 2012. http://hdl.handle.net/2292/19106.

Full text

Abstract:

Approximately two thirds of the fatalities caused by earthquakes in the last one hundred years have resulted due to the collapse of unreinforced masonry (URM) buildings. Poor performance of URM buildings was also observed in recent earthquakes such as the 2005 Pakistan earthquake, the 2008 Sichuan earthquake, the 2009 L'Aquila earthquake and the 2010/2011 Canterbury (New Zealand) earthquake sequence. The New Zealand URM building stock consists of mostly pre-1931 structures, with many of these buildings contributing to the country's architectural heritage. It was revealed in a recent survey that many of New Zealand's URM buildings have insufficient capacity to endure even a moderate earthquake but the concerns of heritage preservation makes demolition of these historic URM buildings undesirable, which results in seismic retrofit being necessary. Many seismic retrofit solutions have already been implemented in New Zealand, but the experimental database on their seismic behaviour is scarce. Consequently, the research reported here was undertaken to investigate the performance of URM walls when seismically retrofitted using three strengthening techniques, which were selected after an extensive literature review. The selected strengthening techniques are (i) unbonded posttensioning using threaded steel rods and sheathed greased strands, (ii) near surface mounting of high strength twisted stainless steel bars (NSM-TS), and (iii) surface application of polymer textile reinforced mortar (TRM). The selected seismic strengthening techniques were adapted for New Zealand URM buildings, and the performance of URM walls seismically strengthened using the adapted strengthening techniques was investigated by performing numerous full scale laboratory based and field tests. Based on the results of the experimental program empirical design equations were derived and checked for accuracy by comparing with current design equations and with experimental results. Finally, case studies were conducted to demonstrate application of these strengthening techniques for the seismic retrofit of historic URM buildings.

APA, Harvard, Vancouver, ISO, and other styles

15

Dasios, Aristotelis. "Computer techniques for in-situ seismic attenuation studies and their applications." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555863.

Full text

Abstract:

Previous workers have demonstrated that the anelastic energy loss of a seismic wave is related to the petrophysical and mineralogical properties of the rock through which it is propagating. The objectives of the work described in this thesis are the design and development of stable computer techniques for measuring anelastic energy loss (attenuation) from full-waveform sonic data and surface seismic surveys of hydrocarbon reservoirs, to explore these relationships in-situ. Software for anelastic attenuation analysis of borehole and surface seismic data was developed within the ProMAX processing system environment. New and established attenuation estimation techniques were implemented using borehole and surface seismic data from a gas reservoir, and seismic data from shallow boreholes in fractured rocks. The Logarithm Spectral Ratio (LSR) and the Instantaneous Frequency (IF) methods were developed for full-waveform sonic data from a long spacing multi-receiver tool. The two methods provide independent estimates of attenuation, as the LSR method uses the whole spectrum of the seismic pulse whilst the IF method detects shifts in the centre frequency of the pulse spectra. Attenuation was successfully estimated with both of these methods from sonic data acquired within a gas-bearing reservoir, and the IF method was found to be superior to the LSR method. An indirect measure of attenuation from sonic data, the Peak Instantaneous Frequency attribute (PIF), gave very stable measurements in low attenuation regions where the conventional techniques were unstable. - The resolution and stability of the attenuation logs was increased by combining attenuation estimates from multiple receiver pairs of the sonic tool, using a least-squares inversion approach. Both P- and S-wave attenuation were estimated from waveform sonic data acquired in a gas-bearing reservoir. Although the P-wave attenuation estimates had smaller measurement errors compared to the S-wave estimates, they were more strongly affected by borehole fluid invasion. The relationships between attenuation and other petrophysical measurements from the same well were examined. Difficulties were encountered in the interpretation of the P-wave logs because of the possibility of invasion whilst neural network analysis of the S-wave attenuation measurements ii suggested potential correlation between attenuation and permeability. Manual and automated techniques were implemented for detecting attenuation anomalies from surface reflection data in the same gas reservoir. The Weighted Peak Instantaneous Frequency attribute (WPIF) which provides an indirect measure of the level of attenuation gave maximum stability and resolution, and indicated high energy absorption in the reservoir region. Comparison of the WPIF estimates from log and surface seismic data, using forward WPIF modelling, showed similar frequency variation within the gas reservoir. Attenuation estimates obtained from shallow borehole seismic measurements 111 fractured rocks, using similar techniques, suggested potential correlation between high attenuation regions and fracturing and gave indications of the high sensitivity of attenuation to fracturing.

APA, Harvard, Vancouver, ISO, and other styles

16

Stabile, Tony Alfredo <1977&gt. "High frequency seismic and underwater acoustic wave propagation and imaging techniques." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/1145/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Ghorbani, Komsari Sajjad. "Seismic Risk Assessment of Wood Frame Construction Using Fuzzy Based Techniques." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31450.

Full text

Abstract:

Wood-framed buildings have generally performed well during earthquake events, resulting in low fatality levels. However, various degrees of damage is still observed in these buildings during previous earthquakes. Lessons learned from the performance of wood frame construction in these earthquakes is led to an improvement in the design codes and construction practices over the past decades. But, the existing buildings are still vulnerable, since they were designed based on the older codes or constructed using old construction practices. Wood frame construction is the most common construction type in Canada, especially for single family dwellings. Most of these buildings are old, built prior to any modern seismic requirement, and have not been retrofitted against the damaging effects of earthquakes. Therefore, with a number of Canadians living in areas of high or moderate earthquake risk, there is a need to develop tools to assess the seismic vulnerability of the exiting wood-framed buildings in Canada. In the following thesis, a risk-based visual seismic assessment model and a screening tool (CanRisk) is developed, to assess the seismic vulnerability of existing wood frame construction in Canada. The model is dependent on the seismic hazard, building vulnerability, and building importance/exposure, which are integrated using hierarchical fuzzy rule based modeling. In the proposed seismic assessment model, fuzzy logic is used as a computing technique to capture the vagueness and uncertainty of a seismic vulnerability assessment, caused by subjectivity involved in the evaluation process. The hierarchical fuzzy rule based modeling used in this seismic assessment method is implemented in a prototype Matlab based program (CanRisk), which incorporates the Canadian seismic design practice based on the National Building Code of Canada (NBCC) and the Canadian site seismic hazard. A sensitivity analysis is conducted to test and verify the seismic assessment model and investigate the effects of various parameters on the outcome of the assessment. Also, in a case study, selected wood-framed buildings located in the city of Ottawa are evaluated using CanRisk, to demonstrate the applicability of the program.

APA, Harvard, Vancouver, ISO, and other styles

18

Takahata, André Kazuo 1982. "Unidimensional and bidimensional seismic deconvolution = Deconvolução sísmica unidimensional e bidimensional." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261103.

Full text

Abstract:

Orientador: Renato da Rocha Lopes
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-25T08:10:05Z (GMT). No. of bitstreams: 1 Takahata_AndreKazuo_D.pdf: 10418132 bytes, checksum: 71c4bb92534425059f1397eb4fc919a2 (MD5) Previous issue date: 2014
Resumo: Neste trabalho consideramos técnicas de processamento de sinais que têm como objetivo aumentar a resolução de imagens da subsuperfície geradas com dados sísmicos. Uma das técnicas consideradas é a deconvolução unidimensional, que tem como finalidade eliminar distorções causadas pelas limitações em banda de frequência da fonte sísmica, bem como pela absorção de componentes e distorções de fase ocorridas durante a propagação da onda sísmica. Nesta tese, analisamos tanto métodos chamados supervisionados, em que estão disponíveis medidas adicionais às medidas sísmicas, que podem guiar o processo de deconvolução, quanto os métodos não supervisionados, em que apenas as medidas sísmicas são consideradas. Em particular, tratamos dos métodos de filtragem de Wiener e mínimos quadrados para os métodos supervisionados. Nos métodos não supervisionados, discutimos as hipóteses para o funcionamento dos métodos envolvendo as estatísticas referentes à refletividade de subsuperfície e do espectro de fase do pulso sísmico. Em particular, analisamos principalmente uso do filtro de erro de predição, que utiliza estatísticas de segunda ordem (SOS) e requer um pulso de fase mínima, e mostramos nossa contribuição sobre um método que utiliza estatísticas de ordem superior (HOS) chamado de "banded independent component analysis" (B-ICA) e que não exige que o pulso seja de fase mínima. Por fim, realizamos um estudo de caso envolvendo dados obtidos em um poço e dados sísmicos com fim de ilustrar nossa análise. Na deconvolução bidimensional são tratadas, além das distorções pela fonte sísmica consideradas na abordagem unidimensional, distorções causadas pela geometria de aquisição de dados e de variações de velocidade de propagação sísmica causadas por complexidades geológicas. Tais distorções podem ser quantificadas em imagens sísmicas obtidas pela técnica de imageamento chamada migração em profundidade pré-empilhamento (PSDM) por meio de uma relação de convolução bidimensional entre a refletividade da subsuperfície e uma função de resolução. Sob hipóteses adequadas, a função de resolução pode ser modelada como uma função de espalhamento pontual (PSF) e a deconvolução bidimensional, portanto, consiste em atenuar o efeito dessas PSFs. Neste trabalho revisamos os aspectos básicos desta modelagem e da estimação das PSFs, bem como do processo de imageamento, e mostramos a nossa contribuição para a deconvolução bidimensional por meio de um método de filtragem inversa
Abstract: In this work, we consider signal processing techniques that aim to improve the resolution of images of the subsurface of the Earth generated from seismic data. One such technique is uni-dimensional deconvolution, which aims to eliminate distortions caused by limitations in the seismic source frequency band, as well as distorting effects caused by frequency components absorption and phase changes during seismic propagation. We analyze both supervised methods, in which reference signals are used in addition to the seismic measurements to determine the decovolution filter, as well as unsupervised methods, in which only the seismic measurements are used. Particularly, we analyze Wiener filtering and least squares methods on the supervised case. As for the unsupervised algorithms, we discuss the hypotheses that underlie these methods, which are based on the statistics of the reflectivity of the subsurface and the phase spectrum of the wavelet pulse. We analyze especially the use of the prediction error filter, which uses second order statistics (SOS) and requires a minimum phase wavelet, and we show our contribution on a method that uses higher order statistics (HOS) called banded independent component analysis (B-ICA), which does not requires that the wavelet be minimum phase. We also present a case study using log data measured in a borehole and seismic data in order to illustrate our analysis. In bidimensional deconvolution, we consider, besides the seismic source distortions considered in the 1D approach, distortions in seismic imaging caused by the acquisition geometry and velocity model complexity associated with the geological structure of the subsurface. These distortions can be quantified in seismic images created through the technique called prestack depth migration (PSDM) using a 2D convolution model between the reflectivity of the subsurface and the so-called resolution function. Under appropriate hypotheses, the resolution function can be seen as a point spread function (PSF). Thus, the objective of 2D deconvolution is to attenuate the effect of these PSFs. In this work, we review the basic aspects of the 2D convolutional model and PSF estimation, as well as the imaging process, and we show our contribution on 2D deconvolution using an inverse filtering approach
Doutorado
Telecomunicações e Telemática
Doutor em Engenharia Elétrica

APA, Harvard, Vancouver, ISO, and other styles

19

Palmer, Derecke School of Geology UNSW. "Digital processing of shallow seismic refraction data with the convolution section." Awarded by:University of New South Wales. School of Geology, 2001. http://handle.unsw.edu.au/1959.4/19275.

Full text

Abstract:

The refraction convolution section (RCS) is a simple and efficient method for full trace processing of shallow seismic refraction data. It facilitates improved interpretation of shallow seismic refraction data through the convenient use of amplitudes as well as traveltimes. The RCS is generated by the convolution of forward and reverse shot records. The convolution operation effectively adds the first arrival traveltimes of each pair of forward and reverse traces and produces a measure of the depth to the refracting interface in units of time which is equivalent to the time-depth function of the generalized reciprocal method (GRM). The convolution operation also multiplies the amplitudes of first arrival signals. This operation compensates for the large effects of geometric spreading to a very good first approximation, with the result that the convolved amplitude is essentially proportional to the square of the head coefficient. The head coefficient is approximately proportional to the ratio of the specific acoustic impedances in the upper layer and in the refractor, where there is a reasonable contrast between the specific acoustic impedances in the layers. The RCS can also include a separation between each pair of forward and reverse traces in order to accommodate the offset distance in a manner similar to the XY spacing of the GRM. Lateral variations in the near-surface soil layers can effect amplitudes thereby causing 'amplitude statics'. Increases in the thickness of the surface soil layer correlate with increases in refraction amplitudes. These increases are adequately described and corrected with the transmission coefficients of the Zoeppritz equations. The minimum amplitudes, rather than an average, should be used where it is not possible to map the near surface layers. The use of amplitudes with 3D data effectively improves the spatial resolution by almost an order of magnitude. Amplitudes provide a measure of refractor wavespeeds at each detector, whereas the analysis of traveltimes provides a measure over several detectors, commonly a minimum of six. The ratio of amplitudes obtained with different shot azimuths provides a detailed qualitative measure of azimuthal anisotropy. Dip filtering of the RCS removes 'cross-convolution' artifacts and provides a convenient approach to the study of later events. The RCS facilitates the stacking of refraction data in a manner similar to the CMP methods of reflection seismology. It can improve signal-to-noise ratios.

APA, Harvard, Vancouver, ISO, and other styles

20

Sarrazin, Jacques. "A comparative analysis of seismic retrofit techniques for reinforced concrete bridge columns." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26763.

Full text

Abstract:

Reinforced concrete bridge columns built prior to 1971 cannot withstand earthquake forces due to insufficient transverse reinforcement, poor detailing, and lap-splices in the plastic hinge area. In order to correct this deficiency, these piers must be reinforced by confinement in the axis perpendicular to the longitudinal bars. Experimental research as well as field experience has shown that there are a significant number of technologies that are effective column retrofit solutions for the thousands of bridges worldwide that are in need of upgrade. There is a significant amount of documented research dealing with the technical effectiveness of individual techniques, however, very little research has compared these techniques for cast effectiveness and functionality. This dissertation addresses this issue by analyzing and conducting feasibility assessments of existing technologies, providing detailed retrofit designs for 6 circular and 6 square columns using four different approaches: steel jackets, FRP wrapping, concrete jackets and external pre-stressing and by pricing all of these designs. From this data, conclusions are drawn concerning the cost effectiveness of the four technologies. This study also analyses bridge assessment techniques.

APA, Harvard, Vancouver, ISO, and other styles

21

El, Sabbagh Amid. "Seismic Risk Assessment of Unreinforced Masonry Buildings Using Fuzzy Based Techniques for the Regional Seismic Risk Assessment of Ottawa, Ontario." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30508.

Full text

Abstract:

Unreinforced masonry construction is considered to be the most vulnerable forms of construction as demonstrated through recent earthquakes. In Canada, many densely populated cities such as (Vancouver, Montreal and Ottawa) have large inventories of seismically vulnerable masonry structures. Although measures have been taken to rehabilitate and increase the seismic resistance of important and historic structures, many existing unreinforced masonry structures have not been retrofitted and remain at risk in the event of a large magnitude earthquake. There is therefore a need to identify buildings at risk and develop tools for assessing the seismic vulnerability of existing unreinforced masonry structures in Canada. This thesis presents results from an ongoing research program which forms part of a multi-disciplinary effort between the University of Ottawa’s Hazard Mitigation and Disaster Management Research Centre and the Geological Survey of Canada (NRCAN) to assess the seismic vulnerability of buildings in dense urban areas such as Ottawa, Ontario. A risk-based seismic assessment tool (CanRisk) has been developed to assess the seismic vulnerability of existing unreinforced masonry and reinforced concrete structures. The seismic risk assessment tool exploits the use of fuzzy logic, a soft computing technique, to capture the vagueness and uncertainty within the evaluation of the performance of a given building. In order to conduct seismic risk assessments, a general building inventory and its spatial distribution and variability is required for earthquake loss estimations. The Urban Rapid Assessment Tool (Urban RAT) is designed for the rapid collection of building data in urban centres. This Geographic Information System (GIS) based assessment tool allows for intense data collection and revolutionizes the traditional sidewalk survey approach for collecting building data. The application of CanRisk and the Urban RAT tool to the City of Ottawa is discussed in the following thesis. Data collection of over 13,000 buildings has been obtained including the seismic risk assessment of 1,465 unreinforced masonry buildings. A case study of selected URM buildings located in the City of Ottawa was conducted using CanRisk. Data obtained from the 2011 Christchurch Earthquake in New Zealand was utilized for verification of the tool.

APA, Harvard, Vancouver, ISO, and other styles

22

Said, Dhiya Mustafa Mohamed. "Reservoir geophysics of the Clyde field : the development and application of quantitative analysis techniques." Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327396.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Köhler, Andreas. "Recognition and investigation of temporal patterns in seismic wavefields using unsupervised learning techniques." Phd thesis, Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2009/2970/.

Full text

Abstract:

Modern acquisition of seismic data on receiver networks worldwide produces an increasing amount of continuous wavefield recordings. Hence, in addition to manual data inspection, seismogram interpretation requires new processing utilities for event detection, signal classification and data visualization. Various machine learning algorithms, which can be adapted to seismological problems, have been suggested in the field of pattern recognition. This can be done either by means of supervised learning using manually defined training data or by unsupervised clustering and visualization. The latter allows the recognition of wavefield patterns, such as short-term transients and long-term variations, with a minimum of domain knowledge. Besides classical earthquake seismology, investigations of temporal patterns in seismic data also concern novel approaches such as noise cross-correlation or ambient seismic vibration analysis in general, which have moved into focus within the last decade. In order to find records suitable for the respective approach or simply for quality control, unsupervised preprocessing becomes important and valuable for large data sets. Machine learning techniques require the parametrization of the data using feature vectors. Applied to seismic recordings, wavefield properties have to be computed from the raw seismograms. For an unsupervised approach, all potential wavefield features have to be considered to reduce subjectivity to a minimum. Furthermore, automatic dimensionality reduction, i.e. feature selection, is required in order to decrease computational cost, enhance interpretability and improve discriminative power. This study presents an unsupervised feature selection and learning approach for the discovery, imaging and interpretation of significant temporal patterns in seismic single-station or network recordings. In particular, techniques permitting an intuitive, quickly interpretable and concise overview of available records are suggested. For this purpose, the data is parametrized by real-valued feature vectors for short time windows using standard seismic analysis tools as feature generation methods, such as frequency-wavenumber, polarization, and spectral analysis. The choice of the time window length is dependent on the expected durations of patterns to be recognized or discriminated. We use Self-Organizing Maps (SOMs) for a data-driven feature selection, visualization and clustering procedure, which is particularly suitable for high-dimensional data sets. Using synthetics composed of Rayleigh and Love waves and three different types of real-world data sets, we show the robustness and reliability of our unsupervised learning approach with respect to the effect of algorithm parameters and data set properties. Furthermore, we approve the capability of the clustering and imaging techniques. For all data, we find improved discriminative power of our feature selection procedure compared to feature subsets manually selected from individual wavefield parametrization methods. In particular, enhanced performance is observed compared to the most favorable individual feature generation method, which is found to be the frequency spectrum. The method is applied to regional earthquake records at the European Broadband Network with the aim to define suitable features for earthquake detection and seismic phase classification. For the latter, we find that a combination of spectral and polarization features favor S wave detection at a single receiver. However, SOM-based visualization of phase discrimination shows that clustering applied to the records of two stations only allows onset or P wave detection, respectively. In order to improve the discrimination of S waves on receiver networks, we recommend to consider additionally the temporal context of feature vectors. The application to continuous recordings of seismicity close to an active volcano (Mount Merapi, Java, Indonesia) shows that two typical volcano-seismic events (VTB and Guguran) can be detected and distinguished by clustering. In contrast, so-called MP events cannot be discriminated. Comparable results are obtained for selected features and recognition rates regarding a previously implemented supervised classification system. Finally, we test the reliability of wavefield clustering to improve common ambient vibration analysis methods such as estimation of dispersion curves and horizontal to vertical spectral ratios. It is found, that in general, the identified short- and long-term patterns have no significant impact on those estimates. However, for individual sites, effects of local sources can be identified. Leaving out the corresponding clusters, yields reduced uncertainties or allows for improving estimation of dispersion curves.
Die Anzahl der weltweit kontinuierlich aufzeichnenden seismischen Messstationen ist in den vergangenen Jahren immer weiter angestiegen. Aus diesem Grund steht eine große Menge von seismischen Datensätzen zu Forschungszwecken zur Verfügung. Insbesondere betrifft dies passive Verfahren zur geologischen Strukturerkundung entweder mittels transienter Ereignisse wie Erdbeben oder unter der Verwendung der permanent vorhandenen natürlichen seismischen Bodenunruhe. Die Bearbeitung dieser Daten erfordert neben der klassischen manuellen Seismogrammanalyse verstärkt auch den Einsatz automatischer Detektionssysteme. Mit Hilfe von überwachten Lernverfahren, d.h. unter Verwendung von seismischen Signalen deren Auftreten bekannt ist, ist es möglich, unbekannte Muster zu klassifizieren. Im Gegensatz dazu hatte die vorliegende Arbeit zum Ziel, ein allgemeines, unüberwachtes Verfahren zur quantitativen Zerlegung seismischer Wellenfelder zu entwickeln. Dies wird mittels einer automatischen Clusterung von Seismogrammzeitfenstern bzw. über die Visualisierung von zeitlichen Mustern auf unterschiedlichen Zeitskalen erreicht. Als unüberwachtes Lernverfahren, das neben der Clusterung auch eine einfach interpretierbare Visualisierung hoch-dimensionaler Datensätze über eine zweidimensionale Darstellung ermöglicht, wurde der Self-organizing-map Algorithmus (SOM) gewählt. Für automatische Lernverfahren ist die Parametrisierung der Seismogramme mittels Merkmalsvektoren erforderlich. Im vorliegenden Fall wurden möglichst viele potentielle Wellenfeldmerkmale unter Verwendung von verschiedenen seismischen Einzel- und Mehrstationsanalyseverfahren für aufeinanderfolgende kurze Zeitfenster berechnet. Um eine datenadaptive und effiziente Parametrisierung zu erreichen, wurde darüberhinaus ein quantitatives Auswahlverfahren für geeignete Merkmale entwickelt, das über einen mehrstufigen Filter bestehend aus einem Signifikanztest und einer SOM-basierenden Korrelationsanalyse redundante und irrelevante Eigenschaften aussortiert. Mit den neu implementierten Techniken wurden verschiedene Arten von seismischen Datensätzen unter Berücksichtigung verschiedener seismologischer Fragestellungen bearbeitet. Die Algorithmen und deren Parameter wurden zunächst intensiv und quantitativ mit Hilfe synthetischer Daten getestet und optimiert. Anschließend wurden reale Aufzeichnungen regionaler Erdbeben und vulkanischer Seismizität verwendet. Im ersten Fall konnten geeignete Merkmale zur Detektion und Klassifizierung von Erdbebenwellenphasen gefunden und die Diskriminierung dieser Signale mit Hilfe der SOM-Darstellung untersucht werden. Unter Verwendung des zweiten Datensatzes wurden Cluster typischer vulkano-seismischer Signale am Vulkan Mount Merapi (Java, Indonesien) detektiert, die sich zur Vorhersage von Eruptionen eignen. Beide Anwendungen haben gezeigt, dass, verglichen mit einzelnen Methoden, automatisch gefundene Kombinationen von Merkmalen verschiedener Parametrisierungsverfahren deutlich bessere Klassifizierungsraten zur Folge haben. Zudem können die Erkenntnisse über die Clusterung von seismischen Signalen dazu verwendet werden, verbesserte automatische Klassifizierungssysteme zu entwickeln. Abschließend wurden Aufzeichnungen der natürlichen seismischen Bodenunruhe bearbeitet. Insbesondere konnte der Einfluss kurzzeitiger und längerfristiger Variationen im Wellenfeld auf Methoden zur passiven Strukturerkundung untersucht werden. Es hat sich gezeigt, dass in einzelnen Fällen tageszeitabhängige Muster und lokale seismische Quellen die Ergebnisse negativ beeinflussen können. Die Wellenfeldzerlegung mittels Clusterung hat es erlaubt, diese Signale zu identifizieren und somit von der Analyse auszuschließen.

APA, Harvard, Vancouver, ISO, and other styles

24

Adedeji, Elijah A. "3D Post-stack Seismic Inversion using Global Optimization Techniques: Gulf of Mexico Example." ScholarWorks@UNO, 2016. http://scholarworks.uno.edu/td/2231.

Full text

Abstract:

Seismic inversion using a global optimization algorithm is a non-linear, model-driven process. It yields an optimal solution of the cost function – reflectivity/acoustic impedance, when prior information is sparse. The inversion result offers detailed interpretations of thin layers, internal stratigraphy, and lateral continuity and connectivity of sand bodies. This study compared two stable and robust global optimization techniques, Simulated Annealing (SA) and Basis Pursuit Inversion (BPI) as applied to post-stack seismic data from the Gulf of Mexico. Both methods use different routines and constraints to search for the minimum error energy function. Estimation of inversion parameters in SA is rigorous and more reliable because it depends on prior knowledge of subsurface geology. The BPI algorithm is a more robust deterministic process. It was developed as an alternative method to incorporating a priori information. Results for the Gulf of Mexico show that BPI gives a better stratigraphic and structural actualization due to its capacity to delineate layers thinner than the tuning thickness. The SA algorithm generates both absolute and relative impedances, which provide both qualitative and quantitative characterization of thin-bed reservoirs.

APA, Harvard, Vancouver, ISO, and other styles

25

Hulsey, Josiah D. "Applying modern interpretation techniques to old hydrocarbon fields to find new reserves: A case study in the onshore Gulf of Mexico, U.S.A." ScholarWorks@UNO, 2016. http://scholarworks.uno.edu/td/2160.

Full text

Abstract:

This study shows how the use of modern geological investigative techniques can reopen old, “drained” hydrocarbon fields. Specifically, it looks at the White Castle Field in South Louisiana. This field has pay sections ranging from late Oligocene to late Miocene. The late Oligocene package is underexplored and understudied and contains 3 primary reservoirs (Cib Haz (CH), MW, and MR). This study established the depositional history of these reservoirs. During most of the late Oligocene, the White Castle Salt Dome was located in a minibasin on the continental slope. The CH and MW deposited in this minibasin. The CH is an amalgamation of slumped shelfal limestones, sandstones, and shales deposited during a lowstand systems tract (LST). The MW comprises a shelf-edge delta that is part of a LST. The MR is an incised valley fill located in the continental shelf that was deposited during LST after the minibasin was filled.

APA, Harvard, Vancouver, ISO, and other styles

26

Chin, Eu-Jeen. "High performance vibration isolation techniques for the AIGO gravitational wave detector." University of Western Australia. School of Physics, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0159.

Full text

Abstract:

[Truncated abstract] Interferometric gravitational wave detectors are being built around the world with continually improving measurement sensitivities. Noise levels from sources that are intrinsic to these detectors must be reduced to a level below the gravita- tional wave signal. Seismic noise in the low frequency range, which is within the gravitational wave detection bandwidth, is a concern for earth-based detectors. This thesis presents research and development of a high performance vibration isolation system that is designed to attenuate seismic noise. The final design will be used as part of a fully working interferometer at the Australian International Gravitational Observatory (AIGO). Pendulums and springs are conventionally used for the horizontal and vertical vibration isolation components respectively. A complete system comprises of a cascade of these components, each stage dramatically improving the level of isola- tion. The residual motion at the test mass level is thus reduced but is dominated by the normal mode resonances of the chain. A simple and effective method to reduce residual motion further is to add ultra-low frequency pre-isolation stages which suspend the chain. The Roberts Linkage is a relatively new and simple geometrical structure that is implemented in the pre-isolation stages. Here we present experimental results of improving isolation based on mathematical mod- elling. The attenuation of seismic noise in the vertical direction is almost as important as that in the horizontal direction, due to cross-coupling between the two planes. To help improve the vertical performance a lightweight Euler spring that stores no static energy was implemented into the AIGO suspension system. ... Theoretical and experimental results are presented and discussed. Currently the AIGO laboratory consists of two 80 m length arms. They are aligned along the east and south directions. One of AIGO's top priorities is the installation of two complete vibration isolators in the east arm to form a Fabry-Perot cavity. Assembling two suspension systems will enable more accurate performance measurements of the tuned isolators. This would significantly reduce the measurement noise floor as well as eliminate the seismic noise spectrum due to referencing with the ground motion. The processes involved in preparing such a task is presented, including clean room preparation, tuning of each isolator stage, and local control schematics and methods. The status of the AIGO site is also presented.

APA, Harvard, Vancouver, ISO, and other styles

27

Manuel, Christopher D. "Techniques for improved 2-D Kirchhoff prestack depth imaging." Curtin University of Technology, School of Resource Science and Technology, 2002. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=13308.

Full text

Abstract:

The goal of oil and gas exploration using seismic methods is to accurately locate geological structures that could host such reserves. As the search for these resources tends towards more complex regions, it is necessary to develop methods to extract as much information as possible from the seismic data acquired. Prestack depth imaging is a seismic processing technique that has the capability to produce a realistic depth image of geological structures in complex situations. However, improvements to this technique are required to increase the accuracy of the final depth image and ensure that the targets are accurately located. Although prestack depth imaging possesses the ability to produce a depth image of the Earth, it does have its disadvantages. Three problematic areas in depth imaging are: the computer run times (and hence costs) are excessively high; the success of depth migration is highly dependent upon the accuracy of the interval velocity model; and seismic multiples often obscure the primary reflection events representative of the subsurface geology. Velocity model building accounts for most of the effort in prestack depth imaging and is also responsible for the likelihood of success. However, the more effort that is expended on this process, the greater the cost of producing the required depth section. In addition, multiples remain a problem in complex depth imaging since many attenuation techniques are based assumptions that may only be approximately correct and in addition require a priori information. The Kirchhoff method is considered to be the workhorse in industry for prestack depth imaging. It is a simple and flexible technique to implement, and usually produces acceptable images at a small fraction of the cost of the other depth migration methods.
However, it is highly dependent on a method for calculating the traveltimes that are required for mapping data from the prestack domain to the output depth section. In addition, it is highly dependent on the accuracy of the interval velocity model. Multiples can also be problematic in complex geological scenarios. To improve the quality of the depth section obtained from Kirchhoff depth imaging, these three issues are considered in this thesis. This thesis took on the challenge of developing new techniques for (a) improving the accuracy and efficiency of traveltimes calculated for use in Kirchhoff prestack depth imaging, (b) building the interval velocity model, and (c) multiple attenuation in complex geological areas. Three new techniques were developed and tested using a variety of numerical models. A new traveltime computation method for simulating seismic multiple reflections was tested and compared with a Promax© finite-difference traveltime solver. The same method was also used to improve the computational efficiency whilst retaining traveltime accuracy. This was demonstrated by application to the well-known Marmousi velocity model and a velocity model obtained from analysis of data from the North West Shelf of Western Australia.
A new interval velocity model building technique that utilises the information contained in multiple events was also implemented and tested successfully using a variety of numerical models. Finally, a new processing sequence for multiple attenuation in the prestack depth domain was designed and tested with promising results being observed. Improved accuracy in the depth image can be obtained by combining the three techniques I have developed. These techniques enable this to be achieved by firstly improving traveltime accuracy and computation efficiency. These benefits are then combined with a more accurate interval velocity model and data with a minimal problematic multiple content to produce an accurate depth image. These new techniques for Kirchhoff depth imaging are capable of producing a depth section with improved accuracy, and with increased efficiency, that will aid in the process of seismic interpretation.

APA, Harvard, Vancouver, ISO, and other styles

28

Baggio, Sebastiano Verfasser], and Martin [Akademischer Betreuer] [Empelmann. "Mitigation techniques of seismic hazard effects on art objects / Sebastiano Baggio ; Betreuer: Martin Empelmann." Braunschweig : Technische Universität Braunschweig, 2018. http://d-nb.info/1175815802/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Baziw, Erick John. "Application of digital filtering techniques for reducing and analyzing in-situ seismic time series." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28364.

Full text

Abstract:

The introduction of digital filtering is a new and exciting approach in analyzing in-situ seismic data. Digital filters are also in the same spirit as the electric cone which replaced the mechanical cone in CPT* testing. That is, it is desirable to automate CPT testing in order to make it less operator dependent and increase the reliability and accuracy. In CPT seismic cone testing seismic waves are generated at the surface and recorded downhole with velocity or acceleration transducers. The seismic receivers record the different seismic wavelets (e.g., SV-waves, P-waves) allowing one to determine shear and compression wave velocities. In order to distinguish the different seismic events, an instrument with fast response time is desired (i.e., high natural frequency and low damping). This type of instrument is characteristic of an accelerometer. The fast response time (small time constant) of an accelerometer results in a very sensitive instrument with corresponding noisy time domain characteristics. One way to separate events is to characterize the signal frequencies and remove unwanted frequencies. Digital filtering is ideal for this application. The techniques of digital filtering introduced in this research are based on frequency domain filtering, where Fast Fourier, Butterworth Filter, and crosscorrelation algorithms are implemented. One based on time domain techniques, where a Kalman Filter is designed to model'the instrument and the physical environment. The crosscorrelation method allows one to focus on a specific wavelet and use all the information of the wavelets present averaging out any noises or irregularities and relying upon dominant responses. The Kalman Filter was applied in a manner in which it modelled the sensors used and the physical environment of the body waves and noise generation. The KF was investigated for its possible application to obtaining accurate estimates on the P-wave and S-wave amplitudes and arrival times. The KF is a very flexible tool which allows one to model the problem considered accurately. In addition, the KF works in the time domain which removes many of the limitations of the frequency domain techniques. The crosscorrelation filter concepts are applied by a program referred to as CROSSCOR. CROSSCOR is a graphics interactive program which displays the frequency spectrums, unfiltered and filtered time series and crosscorrelations on a mainframe graphics terminal which has been adapted to run on the IBM P.C. CROSSCOR was tested for performance by analyzing synthetic and real data. The results from the analysis on both synthetic and real data indicate that CROSSCOR is an accurate and user friendly tool which greatly assists one in obtaining seismic velocities. The performance of the Kalman Filter was analyzed by generating a source wavelet and passing it through the second order instrumentation. The second order response is then fed into the KF with the arrival time and maximum amplitude being determined. The filter was found to perform well and it has much promise in respect that if it is finely turned, it would be possible to obtain arrival times and amplitudes on line resulting in velocities and damping characteristics, respectively. * Cone Penetration Test
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

APA, Harvard, Vancouver, ISO, and other styles

30

Karamanci, Emre. "Collapse assessment and performance-based evaluation techniques for concentrically braced frames designed in seismic regions." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117045.

Full text

Abstract:

Performance-Based Earthquake Engineering necessitates the development of simulation models that can predict the nonlinear behavior of structural components as part of a building subjected to seismic loading. For reliable seismic assessment of buildings, these models need to be calibrated with large sets of experimental data. This thesis advances the state-of-knowledge on the collapse assessment of concentrically braced frames (CBFs) designed in seismic regions. The thesis discusses the development of a database that includes extensive information from more than 300 tests of steel braces that have been conducted worldwide over the past 40 years. Statistical information of various properties of steel braces that can be used for quantification of modeling uncertainties is summarized and implications regarding the expected yield properties of various steel types as part of current design provisions are discussed. The steel brace database is utilized to develop drift-based and dual-parameter fragility curves for different damage states of steel braces. These curves can be used as tools for rapid estimation of earthquake damage towards the next generation of performance-based evaluation methods for new and existing buildings. Through extensive calibrations of an inelastic fiber-based steel brace cyclic model, modeling recommendations for the post-buckling behaviour and fracture of steel braces due to low-cycle fatigue are developed for three different brace shapes. The effectiveness of these recommendations is demonstrated through two case studies including concentrically braced frames (CBFs) subjected to earthquake loading. The emphasis is on the accurate assessment of the collapse capacity of concentrically braced frames with the explicit consideration of strength and stiffness deterioration of various structural components that are part of local story mechanisms that develop in CBFs after the steel braces fracture. The influence of modeling classical damping on the collapse capacity of CBFs is also discussed.
Le génie parasismique basé sur la performance des structures nécessite le développement des modèles de simulation qui peuvent estimer le comportement non-linéaire des composantes structurales faisant partie d'un bâtiment sujet ti aux efforts sismiques. Afin d'avoir une évaluation sismique fiable, les modèles doivent être étalonnés avec un grand inventaire de données obtenues expérimentalement. Cette thèse avance l'état des connaissances sur l'évaluation de l'effondrement des contreventements en treillis concentrique conçus dans les régions sismiques. Cette thèse adresse le développement d'une banque de données qui inclut plus de 300 essais effectués autour du monde sur des contreventements en acier depuis plus de 40 ans. Les données statistiques de plusieurs propriétés du contreventement en acier qui peuvent être utilisées pour la quantification des incertitudes de la modélisation sont résumées. Également les implications reliées aux propriétés limi d l'élasticité qui sont attendues selon le type d'acier sont présentées en fonction des règles d'actuelles de conception. La banque de données des contreventements en acier est utilisée afin de développer des drift-based et dual-parameter fragility curves courbes de fragilité à deux paramètres en fonction du déplacement horizontal relatif de l'étage pour différents degrés de dommage. Ces courbes servant à estimer efficacement et rapidement les dommages sismiques, amènt vers la prochaine génération des méthodes d'évaluation de la performance des structures. À travers une vérification approfondie de l'étalonnement du modèle non-linéaire cyclique à fibres du contreventement en acier des recommandations de modélisation du postflambement et de la rupture en fatigue oligocyclique sont développées pour trois différentes types de contreventement. L'efficacité de ces recommandations est démontrée à travers des études de cas incluantes des contreventements concentriques qui reprisent des efforts sismiques. L'accent est mis sur l'évaluation précise de la capacité de l'effondrement des contreventements en treillis concrentriques en prenant en compte explicitement le processus de dégradation de la capacité et de la rigidité des plusieurs composants structuraux qui font partie des mécanismes du dommage local qui s'évoluentdans différents étages d'une structure en contreventements concentriques en acier une fois que le contreventement s'est fracturé. L'effet de la modélisation de l'amortissement de la structure sur la capacité à l'effondrement des contreventements concentriques en acier est également considéré.

APA, Harvard, Vancouver, ISO, and other styles

31

Korany, Yasser Drysdale Robert G. "Rehabilitation of masonry walls using unobtrusive FRP techniques for enhanced out-of-plane seismic resistance /." *McMaster only, 2004.

Find full text

APA, Harvard, Vancouver, ISO, and other styles

32

Shrestha, Kshitij Charana. "Development of Seismic Retrofitting Techniques for Historical Masonry Structures with Application of High Performance Materials." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/151970.

Full text

APA, Harvard, Vancouver, ISO, and other styles

33

Biedler, Murray W. "Delineation of buried stream channels using geophysical techniques." Thesis, Rhodes University, 1994. http://hdl.handle.net/10962/d1005498.

Full text

Abstract:

This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study

APA, Harvard, Vancouver, ISO, and other styles

34

Hollis, Gaylon C. "Non-Invasive Acoustic Emission Testing of Compressed Trabecular Bone and Porous Ceramics using Seismic Analysis Techniques." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4816.

Full text

Abstract:

Acoustic emission(AE) is one of the most sensitive techniques to non invasively monitor deformation, fatigue, and fracture of many materials. The purpose of this study was to evaluate the potential to use AE to detect local failure events within porous ceramic materials. The primary material of interest was mineralized trabecular bone. A better understanding of the failure of trabecular bone is highly relevant to skeletal fragility diseases such as osteoporosis. This study sought to develop a post processing technique that could strengthen the relation between the events detected and the phenomena occurring as a specimen is loaded. The deficiency in other techniques is that they did not fully make a quantitative correlation between acoustic emission event characteristics and the physical occurrence of damage events. The study evaluated the use of seismic power laws because these laws were able to attach a quantitative model to an earthquake and its successive aftershocks. Earthquake transmission has similar propagation attributes when compared to acoustic emission; seismic waves radiate from the epicenter of an earthquake. Acoustic waves radiate from the source of energy release in an acoustic emission event. The study measured the acoustic emission response of trabecular bone and highly oriented ceramics. The bone and ceramics were extracted in two perpendicular directions so that the structural orientation was different. The study sought to evaluate if the power-laws could differentiate the acoustic emission response based on varying the material and varying the structural orientation. The samples were quasi-statically compressed; the mechanical and acoustic emission data were simultaneously recorded. The study found that using the seismic power-law did not statistically differentiate the directional orientation for trabecular bone or ceramic specimens. Acoustic emission did indicate that event detection was different for each type of the of material. Correlations were established with the acoustic emission response and the mechanical testing data. These relationships were explainable because of the mechanical properties of the material.

APA, Harvard, Vancouver, ISO, and other styles

35

Strollo, Angelo. "Development of techniques for earthquake microzonation studies in different urban environment." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2011/5380/.

Full text

Abstract:

The proliferation of megacities in many developing countries, and their location in areas where they are exposed to a high risk from large earthquakes, coupled with a lack of preparation, demonstrates the requirement for improved capabilities in hazard assessment, as well as the rapid adjustment and development of land-use planning. In particular, within the context of seismic hazard assessment, the evaluation of local site effects and their influence on the spatial distribution of ground shaking generated by an earthquake plays an important role. It follows that the carrying out of earthquake microzonation studies, which aim at identify areas within the urban environment that are expected to respond in a similar way to a seismic event, are essential to the reliable risk assessment of large urban areas. Considering the rate at which many large towns in developing countries that are prone to large earthquakes are growing, their seismic microzonation has become mandatory. Such activities are challenging and techniques suitable for identifying site effects within such contexts are needed. In this dissertation, I develop techniques for investigating large-scale urban environments that aim at being non-invasive, cost-effective and quickly deployable. These peculiarities allow one to investigate large areas over a relative short time frame, with a spatial sampling resolution sufficient to provide reliable microzonation. Although there is a negative trade-off between the completeness of available information and extent of the investigated area, I attempt to mitigate this limitation by combining two, what I term layers, of information: in the first layer, the site effects at a few calibration points are well constrained by analyzing earthquake data or using other geophysical information (e.g., shear-wave velocity profiles); in the second layer, the site effects over a larger areal coverage are estimated by means of single-station noise measurements. The microzonation is performed in terms of problem-dependent quantities, by considering a proxy suitable to link information from the first layer to the second one. In order to define the microzonation approach proposed in this work, different methods for estimating site effects have been combined and tested in Potenza (Italy), where a considerable amount of data was available. In particular, the horizontal-to-vertical spectral ratio computed for seismic noise recorded at different sites has been used as a proxy to combine the two levels of information together and to create a microzonation map in terms of spectral intensity ratio (SIR). In the next step, I applied this two-layer approach to Istanbul (Turkey) and Bishkek (Kyrgyzstan). A similar hybrid approach, i.e., combining earthquake and noise data, has been used for the microzonation of these two different urban environments. For both cities, after having calibrated the fundamental frequencies of resonance estimated from seismic noise with those obtained by analysing earthquakes (first layer), a fundamental frequency map has been computed using the noise measurements carried out within the town (second layer). By applying this new approach, maps of the fundamental frequency of resonance for Istanbul and Bishkek have been published for the first time. In parallel, a microzonation map in terms of SIR has been incorporated into a risk scenario for the Potenza test site by means of a dedicated regression between spectral intensity (SI) and macroseismic intensity (EMS). The scenario study confirms the importance of site effects within the risk chain. In fact, their introduction into the scenario led to an increase of about 50% in estimates of the number of buildings that would be partially or totally collapsed. Last, but not least, considering that the approach developed and applied in this work is based on measurements of seismic noise, their reliability has been assessed. A theoretical model describing the self-noise curves of different instruments usually adopted in microzonation studies (e.g., those used in Potenza, Istanbul and Bishkek) have been considered and compared with empirical data recorded in Cologne (Germany) and Gubbio (Italy). The results show that, depending on the geological and environmental conditions, the instrumental noise could severely bias the results obtained by recording and analysing ambient noise. Therefore, in this work I also provide some guidelines for measuring seismic noise.
Aufgrund des enormen Wachstums neuer Megastädte und deren Vordringen in gefährdete Gebiete auf der einen Seite sowie der mangelnden Erdbebenvorsorge in vielen Entwicklungsländern auf der anderen Seite sind verbesserte Verfahren für die Beurteilung der Gefährdung sowie eine rasche Umsetzung bei der Raumplanung erforderlich. Im Rahmen der seismischen Gefährdungsabschätzung spielt insbesondere die Beurteilung lokaler Standorteffekte und deren Einfluss auf die durch ein Erdbeben verursachte räumliche Verteilung der Bodenerschütterung eine wichtige Rolle. Es ist daher unabdingbar, mittels seismischer Mikrozonierungsstudien diejenigen Bereiche innerhalb dicht besiedelter Gebiete zu ermitteln, in denen ein ähnliches Verhalten im Falle seismischer Anregung erwartet wird, um daraus eine zuverlässige Basis bei der Risikoabschätzung großer städtischer Gebiete zu erhalten. Aufgrund des schnellen Wachstums vieler Großstädte in Entwicklungsländern ist eine seismische Mikrozonierung zwingend erforderlich, stellt aber auch eine große Herausforderung dar; insbesondere müssen Verfahren verfügbar sein, mit deren Hilfe rasch eine Abschätzung der Standorteffekte durchgeführt werden kann. In der vorliegenden Arbeit entwickle ich daher Verfahren für die Untersuchung in Großstädten, die darauf abzielen, nicht-invasiv, kostengünstig und schnell durchführbar zu sein. Damit lassen sich innerhalb eines relativ kurzen Zeitraums große Gebiete untersuchen, falls der räumlichen Abstand zwischen den Messpunkten klein genug ist, um eine zuverlässige Mikrozonierung zu gewährleisten. Obwohl es eine gegenläufige Tendenz zwischen der Vollständigkeit aller Informationen und der Größe des untersuchten Gebiets gibt, versuche ich, diese Einschränkung durch Verknüpfung zweier Informationsebenen zu umgehen: In der ersten Ebene werden die Standorteffekte für einige Kalibrierungspunkte durch die Analyse von Erdbeben oder mittels anderer geophysikalischer Datensätze (z.B. Scherwellengeschwindigkeitsprofile) bestmöglich abgeschätzt, in der zweiten Ebene werden die Standorteffekte durch Einzelstationsmessungen des seismischen Rauschens für ein größeres Gebiet bestimmt. Die Mikrozonierung erfolgt hierbei mittels spezifischer, fallabhängiger Parameter unter Berücksichtigung eines geeigneten Anknüpfungspunktes zwischen den beiden Informationensebenen. Um diesen Ansatz der Mikrozonierung, der in dieser Arbeit verfolgt wurde, zu präzisieren, wurden in Potenza (Italien), wo eine beträchtliche Menge an Daten verfügbar war, verschiedene Verfahren untersucht. Insbesondere kann das Spektralverhältnis zwischen den horizontalen und vertikalen Seismometerkomponenten, welche für das seismische Rauschen an mehreren Orten aufgenommen wurde, als eine erste Näherung für die relative Verstärkung der Bodenbewegung verwendet werden, um darauf aufbauend die beiden Informationsebenen zu verknüpfen und eine Mikrozonierung hinsichtlich des Verhältnisses der spektralen Intensität durchzuführen. Anschließend führte ich diesen Zwei-Ebenen-Ansatz auch für Istanbul (Türkei) und Bischkek (Kirgisistan) durch. Für die Mikrozonierung dieser beiden Städte habe ich denselben Hybridansatz, der Daten von Erdbeben und von seismischem Rauschen verbindet, verwendet. Für beide Städte wurde nach Gegenüberstellung der Resonanzfrequenz des Untergrunds, die zum einen mit Hilfe des seismischen Rauschens, zum anderen durch Analyse von Erdbebendaten bestimmt worden ist (erste Ebene), eine Karte der Resonanzfrequenz unter Verwendung weiterer Messungen des seismischen Rauschens innerhalb des Stadtgebiets erstellt (zweite Ebene). Durch die Anwendung dieses neuen Ansatzes sind vor kurzem zum ersten Mal auch Karten für die Resonanzfrequenz des Untergrunds für Istanbul und Bischkek veröffentlicht worden. Parallel dazu wurde für das Testgebiet in Potenza eine auf dem spektralen Intensitätsverhältnis (SIR) basierende Mikrozonierungskarte in ein Risikoszenario mittels der Regression zwischen SIR und makroseismischer Intensität (EMS) integriert. Diese Szenariostudie bestätigt die Bedeutung von Standorteffekten innerhalb der Risikokette; insbesondere führt deren Einbeziehung in das Szenario zu einem Anstieg von etwa 50% bei der Zahl der Gebäude, für die ein teilweiser oder gar vollständiger Zusammenbruch erwartet werden kann. Abschließend wurde der im Rahmen dieser Arbeit entwickelte und angewandte Ansatz auf seine Zuverlässigkeit geprüft. Ein theoretisches Modell, das zur Beschreibung des Eigenrauschens verschiedener Instrumente, die in der Regel in Mikrozonierungsstudien (z. B. in Potenza, Istanbul und Bischkek) zum Einsatz kommen, wurde untersucht, und die Ergebnisse wurden mit Daten verglichen, die vorher bereits in Köln (Deutschland) und Gubbio (Italien) aufgenommen worden waren. Die Ergebnisse zeigen, dass abhängig von den geologischen und umgebenden Bedingungen das Eigenrauschen der Geräte die Ergebnisse bei der Analyse des seismischen Rauschens stark verzerren kann. Deshalb liefere ich in dieser Arbeit auch einige Leitlinien für die Durchführung von Messungen des seismischen Rauschens.

APA, Harvard, Vancouver, ISO, and other styles

36

ALGHAMDI, HASAN A. "Dynamic Cone Penetrometer (DCP) Based Evaluation of Sustainable Low Volume Road Rehabilitation Techniques." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1470661119.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Delph, Jonathan, and Jonathan Delph. "Crustal and Upper Mantle Structure of the Anatolian Plate: Imaging the Effects of Subduction Termination and Continental Collision with Seismic Techniques." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/622908.

Full text

Abstract:

The neotectonic evolution of the eastern Mediterranean is intimately tied to interactions between the underthrusting/subducting slab along the southern margin of Anatolia and the overriding plate. The lateral variations in the subduction zone can be viewed as a temporal analogue of the transition between continuous subduction and subduction termination by continent-continent collision. By investigating the lateral variations along this subduction zone in the overriding plate, we can gain insight into the processes that precede continent collision. This dissertation summarizes the results of three studies that focus on different parts of the subduction margin: 1) In the west, where the development of a slab tear represents the transition between continuous and enigmatic subduction, 2) In the east, where continent-continent collision between the Arabian and Eurasian Plate is leading to the development of the third largest orogenic plateau on earth after complete slab detachment, and 3) In central Anatolia, where the subducting slab is thought to be in the processes of breaking up, which is affecting the flow of mantle material leading to volcanism and uplift along the margin. In the first study, we interpret that variations in the composition of material in the downgoing plate (i.e. a change from the subduction of oceanic material to continental material) may have led to the development of a slab tear in the eastern Aegean. This underthrusting, buoyant continental fragment is controlling overriding plate deformation, separating the highly extensional strains of western Anatolia from the much lower extensional strains of central Anatolia. Based on intermediate depth seismicity, it appears that the oceanic portion of the slab is still attached to this underthrusting continental fragment. In the second study, we interpret that the introduction of continental lithosphere into the north-dipping subduction zone at the Arabian-Eurasian margin led to the rollback and eventual detachment of the downgoing oceanic lithosphere attached to the Arabian Plate. After detachment, high rates of exhumation in the overriding plate are recorded due to the removal of the oceanic lithosphere and accompanying rebound of the Arabian continental lithosphere. In the third study, we image a transitional stage between the complete slab breakoff of the second study and the continuous subduction slab of the first study. We interpret that trench-perpendicular volcanism and ~2 km of uplift of flat-lying carbonate rocks along the southern margin of Turkey can be attributed to the rollback and ongoing segmentation of the downgoing slab as attenuated continental material is introduced into the subduction zone. Combining these three studies allows us to understand the terminal processes of a long-lived subduction zone as continental material is introduced.

APA, Harvard, Vancouver, ISO, and other styles

38

Kurt, Efe Gokce. "Investigation Of Strenghthening Techniques Using Pseudo-dynamic Testing." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612181/index.pdf.

Full text

Abstract:

Pseudo-dynamic testing was employed to observe the seismic performance of three different retrofit methods on two story three bay reinforced concrete frame structures. The three test frames have hollow clay tile (HCT) infills in the central bay. All of the test frames represent the seismic deficiencies of the Turkish construction practice such as use of plain reinforcing bars, low strength concrete and insufficient confining steel. Two non-invasive and occupant friendly retrofit schemes suggested in the Turkish Earthquake Code, namely use of Fiber Reinforced Polymers and precast concrete panels integrated on the HCT infills and traditional approach of adding concrete infill wall were employed. Specimens were subjected to three different scale levels of North-South component of Duzce ground motion. Reference specimen experienced severe damage at 100% scale level and reached collapse stage due to the loss of integrity of the infill wall and significant damage on the boundary columns. The retrofitted test structures were able to survive the highest level 140% Duzce ground motion. Test results confirmed the success of the retrofit methods for simulated earthquake loads.

APA, Harvard, Vancouver, ISO, and other styles

39

Reif, Christine. "New techniques for analyzing long-period seismic data to determine 3D thermal and compositional structure of the Earth's mantle /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3185925.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Phillips, William Scott. "The separation of source, path and site effects on high frequency seismic waves : an analysis using coda wave techniques." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/59037.

Full text

Abstract:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1985.
Microfiche copy available in Archives and Science.
Bibliography: leaves 178-185.
by William Scott Phillips.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

41

Papanikolaou, Ioannis. "Generation of high-resolution seismic hazard maps through integration of earthquake geology, fault mechanics theory and GIS techniques in extensional tectonic setting." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406557.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Naderian, Hamidreza. "Advanced Numerical Techniques for Dynamic and Aerodynamic Analysis of Bridges." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36089.

Full text

Abstract:

To meet the economic, social and infrastructure needs of the community for safe and efficient transportation systems, long span bridges have been built throughout the world. Long span bridges are one of the most challenging kinds of structures in civil engineering. The cable-stayed bridges are of great interest mainly as an alternative and a more economic solution than the one of suspension bridges. In addition, the fiber reinforced polymer (FRP) composites are, nowadays, successfully used for constructing modern bridges, where the significant weight saving provides additional benefits. Because of the great flexibility, modern long-span cable-stayed bridges are usually very susceptible to dynamic loads especially to the earthquake and strong winds. Therefore, the earthquake-resistant and wind-resistant designs become one of key issues for successful construction of bridges. The objective of the present research is to develop a very efficient spline finite strip technique, for modelling and analysis of both conventional and hybrid FRP cable-stayed bridges. The study falls into the categories of bending, free vibration, seismic, and aerodynamic flutter analysis. The spline finite strip method (SFSM) is one of the most efficient numerical methods for structural analysis of bridges, reducing the time required for estimating the structural response without affecting the degree of accuracy. In the finite strip method, the degrees of freedom could be significantly reduced due to the semi-analytical nature of this method. However, the previous versions of SFSM are not able to model the entire bridge system. For that reason, the structural interactions between different structural components of the bridge could not be handled. In addition, the vibrations and displacements of the towers and cables could not be investigated. In the present formulation, all these obstacles have been eliminated. Moreover, the proposed finite strip technique is very efficient and accurate due to the drastic reduction in the formulation time, simplicity of data preparation, rapid rate convergence of the results, and the semi-analytical nature. Last but not least, and for the first time, a fully finite strip solution is extended to the area of wind engineering. Using the spline finite strip discretization, the aerodynamic stiffness and mass properties of the long-span cable-stayed bridge are derived. The aerodynamic properties along with the structural properties of long-span plates and bridges are formulated in the aerodynamic equation of motion and are used to analyze the flutter problem. The accuracy and efficiency of the proposed advanced finite strip method is verified against the finite element and field measurement results. The results demonstrate that this methodology and the associated computer code can accurately predict the dynamic and aerodynamic responses of the conventional and FRP long-span cable-stayed bridge systems. The outcome of the present research will lead to a comprehensive structural analysis of bridges in the framework of the proposed discretization which is more efficient and straightforward than the finite element analysis.

APA, Harvard, Vancouver, ISO, and other styles

43

Drukpa, Dowchu. "Imaging the Main Frontal Thrust in Southern Bhutan using high-resolution near-surface geophysical techniques : implications for tectonic geomorphology and seismic hazard assessment." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT101/document.

Full text

Abstract:

Des études récentes menées dans la région de Sarpang au sud du centre du Bhoutan estiment un taux de glissement Holocène de 20,8 +/- 8,8 mm/an sur le chevauchement frontal himalayen (TFT). Cette valeur est basée sur un taux de surrection moyen mesuré de 8,8 +/- 2,1 mm/an et en supposant pour ce chevauchement un pendage constant de 25° +/- 5°. La géométrie des failles est un paramètre clé dans l’estimation de la vitesse de glissement et donc dans l’évaluation de l’aléa sismique. Dans le cadre de ce travail, nous avons utilisé une approche géophysique de proche surface afin d’estimer précisément la géométrie de ce chevauchement.Nous avons déployé des profils géophysiques dans trois sites clés le long de la frontière sud du Bhoutan. La première zone d'étude se trouve à Sarpang, une petite ville située au centre du Bhoutan où nous avons effectué des mesures gravimétriques, sismiques et électriques. Le deuxième site est situé à Phuentsholing dans le sud-ouest du Bhoutan, où nous avons effectué des mesures gravimétriques et de résistivité électrique. Le troisième site est situé entre Sarpang et Phuentsholing, à Lhamoizingkha dans le district de Dagana.Excepté pour la région de Lhamoizingkha, une approche d'inversion stochastique a été adoptée pour analyser des données géophysiques collectées. Contrairement aux approches couramment utilisées basées sur la recherche du modèle le plus simple, les principaux avantages de cette approche sont sa capacité (1) à mieux estimer la géométrie des zones de discontinuité car aucun lissage n'est appliqué, (2) à fournir une mesure des incertitudes sur le pendage obtenu et (3) à permettre une analyse des relations possibles entre les propriétés géométriques et celles du milieu (résistivité électrique, vitesse ou densité).Les résultats d'inversion stochastique du site de Sarpang montrent un TFT qui se caractérise par une géométrie en plat-rampe-plat avec un pendage vers le nord d'environ 20°-30° dans la partie la plus superficielle (profondeur < 5 m), un pendage fort de 70° entre 5 m et 40 m de profondeur et un l'aplatissement avec un pendage de 20° au-delà de 40 m. Ces nouveaux résultats nous permettent d'estimer un taux minimal de glissement de 10 +/- 2 mm/an sur le TFT, soit environ 60% des 17 mm/an associés au taux de convergence GPS moyen obtenu en champ lointain. Sur la base de ces contraintes, il apparait donc qu’on ne puisse pas exclure la possibilité que la déformation soit distribuée sur plusieurs failles, comprenant le TFT, mais également d’autres chevauchements comme le MBT (au nord) ou le FBT (au sud). De plus, en supposant un taux de glissement constant, les variations de pendage obtenues induisent des variations du taux de surrection en fonction de la distance au TFT. Cela souligne les faiblesses des hypothèses couramment faites pour estimer les taux de glissement Holocène sur les failles sismogènes : (1) pendage constant estimé uniquement à partir des observations de surface et (2) estimations du taux de surrection en supposant une surrection identique pour une terrasse fluviale donnée.Contrairement à Sarpang, à Phuentsholing le TFT correspond au chevauchement frontal himalayen (MFT). Sur ce site, l’étude préliminaire que nous avons menée suggère un MFT ayant une géométrie de faille listrique. Des mesures de datations doivent maintenant être effectuées pour estimer le taux de glissement sur le MFT dans cette zone. Dans la région de Lhamoizingkha, l'emplacement exact du MFT n'est pas connu. Nos résultats préliminaires suggèrent une géométrie complexe de la trace de la faille en surface et indiquent que le MFT est situé plus au nord de la ligne de résistivité déployée dans cette zone. À l'instar du site de Phuentsholing (mais contrairement à Sarpang), nous avons observé que le MFT était la structure la plus frontale et que l’essentiel de la convergence dans cette zone pouvait être accommodé par le MFT, comme semble le suggérer les observations GPS
Recent studies based on surface observations from Sarpang area in southern-central Bhutan have estimated the Holocene slip rate of 20.8+/-8.8 mm/year. This value is based on a mean vertical uplift rate of 8.8+/-2.1 mm/year and assuming a constant frontal thrust dip angle of 25°+/-5° extrapolated from structural measurements. Since geometry of the fault is a key parameter for discerning the slip rate and its associated seismic hazard assessment, we employed near-surface geophysical approach to accurately constrain the Topographic Frontal Thrust (TFT) geometry at shallow depth. Based on proven effectiveness of near-surface geophysical techniques for studying active faults, we adopted gravity, seismic and electrical resistivity tomography.We deployed geophysical profiles at three key sites along the southern frontal areas of the Bhutan Himalayas. The first study area is in Sarpang, a small town located in southern-central Bhutan where we performed all three geophysical methods adopted. The second site is located in Phuentsholing in the south-western Bhutan, where we performed gravity and electrical resistivity survey. The third site is located between Sarpang and Phuentsholing, in the sub-district of Lhamoizingkha under Dagana district.A stochastic inversion approach was adopted to perform analysis of geophysical data collected from the above sites expect for Lhamoizingkha area. Unlike commonly used approaches based on search for the simplest model, the main advantages of this approach include its ability (1) to assess the fault geometry because no smoothing is applied, (2) to provide a measurement of the uncertainties on the obtained dip angle and (3) to allow trade-off analysis between geometric and either electrical resistivity, velocity or density properties.The stochastic inversion results from Sarpang site show a TFT that is characterized by a flat and listric-ramp geometry with a north dipping dip angle of ca 20°-30° at the upper depth of 0-5 m, steeply dipping angle of 70° in the middle 5-40 m depth and flattening with a dip angle of 20° at deeper depths. These new results allow us to estimate a minimum overthrusting slip rate of 10+/-2 mm/year on the TFT, which is about 60% of the far-field GPS convergence rate of ca 17 mm/year. Based on these constraints we propose that, in Sarpang site, significant deformation partitioning on different faults including the TFT, the Main Boundary Thrust (MBT) and the Frontal Back Thrust (FBT) cannot be ruled out. More importantly, assuming a constant slip rate, the dip angle variations constrained from the present study, corresponds to variations in the uplift rate with distance from the TFT. This, therefore, emphasizes the drawbacks in assuming constant dip angle measured from surface observations and uplift rate estimates based on terrace dating only at the front, which may significantly bias the slip rate estimation.Unlike in Sarpang, the TFT corresponds to the Main Frontal Thrust (MFT) in Phuentsholing. At this site a preliminary study suggests a MFT characterized by a flat and listric-ramp geometry. With additional terrace dating information, slip rate for the Phuentsholing area will be performed in a near future. Overall based on the stochastic inversion results, we propose a MFT geometry similar to that observed in Sarpang but with possible lateral variations in terms of deformation partitioning. In Lhamoizingkha area, the exact location of the MFT is not known. Our preliminary results suggest a complex fault trace and indicate that the MFT is located further north of the current resistivity line deployed in this area. Similar to Phuentsholing site (but contrary to Sarpang), we observed that the MFT is the most frontal structure and therefore most of the convergence in the area could be accommodated by the MFT, which is also in agreement with GPS observations

APA, Harvard, Vancouver, ISO, and other styles

44

Fernandez, Cesar Aaron Moya. "Two alternative inversion techniques for the determination of seismic site response and propagation-path velocity structure : spectral inversion with reference events and neural networks." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147831.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Chavez, Huerta Brian Francisco, and Castillejo Martín Andree Espíritu. "Aplicación de métodos de inspección y reparación en viviendas de albañileria confinada con presencia de daños en sus elementos estructurales provocado por un sismo." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2019. http://hdl.handle.net/10757/628110.

Full text

Abstract:

Los sismos a través del tiempo han sido perjudiciales en el desarrollo de construcciones hechas por el hombre. Un sismo es un movimiento repentino del terreno producido por fuerzas que actúan en el interior del planeta; sus orígenes son numerosos pero el más importante son los choques entre las placas tectónicas. Respecto a las estructuras dañadas por el sismo, en la mayoría de los casos, son las viviendas familiares las que se ven perjudicadas en mayor medida, son muchas las causas, pero uno de los más importantes es la construcción de edificaciones de albañilería confinada realizadas sin ningún parámetro ingenieril (Hermosa, 2003). Por ello, cuando ocurre un sismo suele aparecer fallas en sus elementos estructurales, que en algunos casos no se le toma la debida importancia por el usuario, vale mencionar que este acto no es el correcto debido a que, si ocurriera un sismo de alta magnitud podría colapsar y como consecuencia se perderían vidas humanas. Por esta razón, a todos los profesionales dedicados al rubro de la construcción les es imprescindible contar con nociones de inspección de los daños estructurales y asimismo saber repararlas. En este documento se aprenderá las diferentes aplicaciones de métodos de inspección de fisuras en elementos estructurales tanto en columnas, vigas y muros, pero enfocado principalmente en el muro ya que, en esta técnica constructiva, el muro es el que soporta los esfuerzos, este análisis será de dos formas: Evaluación rápida y evaluación detallada. En la evaluación rápida, se determina rápidamente el riesgo o seguridad que representa la estructura; esta información será almacenada en una aplicación, el cual será la herramienta para la evaluación con el fin de determinar el nivel de seguridad de la vivienda, las cuales son seguridad total, habitable, cuidado e insegura, estableciendo de esta manera si la vivienda es habitable o no (Pinto y Torres, 2016). Finalmente, si la vivienda se encontrase en el nivel de seguridad de cuidado o insegura se pasará a una evaluación detallada; en esta evaluación se recomienda una inspección no mayor a 6 horas. En la evaluación detallada, se realiza una reevaluación de acuerdo a los niveles establecidos en la evaluación rápida, centrándose en los últimos niveles, cuidado e inseguro, respectivamente; se determinará las causas que originaron los daños, así como la magnitud de daños en los elementos estructurales a través de equipos de inspección, siendo algunos de ellos, el pacómetro y el comparador; para la posterior aplicación de diversos métodos de reparación. Finalmente, la reparación involucra la inyección de resina epoxi en grietas, reforzamiento con fibra de carbono, malla electrosoldada, entre otros. El éxito de la aplicación de estos métodos tiene como objetivo lograr disminuir el porcentaje de probabilidad de colapso y eliminar la pérdida de vidas humanas que se realizará mediante un modelamiento de la vivienda reparada la cual tendrá que cumplir con las normas de diseño sismorresistente. Como resultado de este modelamiento en Etabs se pudo comprobar que efectivamente tras la reparación a través de fibra de carbono y malla electrosoldada en los muros de albañilería confinada, la estructura es capaz de soportar sismos de igual o mayor magnitud.
Earthquakes over time have been detrimental in the development of man-made constructions. An earthquake is a sudden movement of the land produced by forces acting inside the planet; Its origins are numerous but the most important are the clashes between the tectonic plates. Regarding the structures damaged by the earthquake, in most cases, it is family homes that are harmed to a greater extent, there are many causes, but one of the most important is the construction of confined masonry buildings made without no engineering parameter (Hermosa, 2003). Therefore, when an earthquake occurs, failures usually appear in its structural elements, which in some cases do not take due importance by the user, it is worth mentioning that this act is not correct because, if a high magnitude earthquake occurs It could collapse and as a result human lives would be lost. For this reason, all professionals dedicated to the construction sector are essential to have notions of inspection of structural damage and also know how to repair them. In this document we will learn the different applications of methods of inspection of fissures in structural elements both in columns, beams and walls, but focused mainly on the wall since, in this construction technique, the wall is the one that supports the efforts, this analysis It will be in two ways: Rapid evaluation and detailed evaluation. In the rapid assessment, the risk or safety of the structure is quickly determined; This information will be stored in an application, which will be the tool for the evaluation in order to determine the level of security of the house, which are total, habitable, careful and insecure security, establishing in this way if the house is habitable or not (Pinto y Torres, 2016). Finally, if the house is at the level of care or insecurity, a detailed evaluation will be carried out; In this evaluation, an inspection of no more than 6 hours is recommended. In the detailed evaluation, a reassessment is carried out according to the levels established in the rapid evaluation, focusing on the last levels, careful and insecure, respectively; the causes that caused the damage will be determined, as well as the magnitude of damage to the structural elements through inspection equipment, some of them being the pacometer and the comparator; for the subsequent application of various repair methods. Finally, the repair involves the injection of epoxy resin in cracks, reinforcement with carbon fiber, welded mesh, among others. The success of the application of these methods aims to reduce the likelihood of collapse and eliminate the loss of human lives that will be done through a modeling of repaired housing which will have to comply with seismic-resistant design standards. As a result of this modeling in Etabs, it was found that after the repair through carbon fiber and welded mesh in the confined masonry walls, the structure is capable of withstanding earthquakes of equal or greater magnitude.
Tesis

APA, Harvard, Vancouver, ISO, and other styles

46

Li, Gengxiang. "Rehaussement et détection des attributs sismiques 3D par techniques avancées d'analyse d'images." Phd thesis, Université Michel de Montaigne - Bordeaux III, 2012. http://tel.archives-ouvertes.fr/tel-00731886.

Full text

Abstract:

Les Moments ont été largement utilisés dans la reconnaissance de formes et dans le traitement d'image. Dans cette thèse, nous concentrons notre attention sur les 3D moments orthogonaux de Gauss-Hermite, les moments invariants 2D et 3D de Gauss-Hermite, l'algorithme rapide de l'attribut de cohérence et les applications de l'interprétation sismique en utilisant la méthode des moments.Nous étudions les méthodes de suivi automatique d'horizon sismique à partir de moments de Gauss-Hermite en cas de 1D et de 3D. Nous introduisons une approche basée sur une étude multi-échelle des moments invariants. Les résultats expérimentaux montrent que la méthode des moments 3D de Gauss-Hermite est plus performante que les autres algorithmes populaires.Nous avons également abordé l'analyse des faciès sismiques basée sur les caractéristiques du vecteur à partir des moments 3D de Gauss -Hermite, et la méthode de Cartes Auto-organisatrices avec techniques de visualisation de données. L'excellent résultat de l'analyse des faciès montre que l'environnement intégré donne une meilleure performance dans l'interprétation de la structure des clusters.Enfin, nous introduisons le traitement parallèle et la visualisation de volume. En profitant des nouvelles performances par les technologies multi-threading et multi-cœurs dans le traitement et l'interprétation de données sismiques, nous calculons efficacement des attributs sismiques et nous suivons l'horizon. Nous discutons également l'algorithme de rendu de volume basé sur le moteur Open-Scene-Graph qui permet de mieux comprendre la structure de données sismiques.

APA, Harvard, Vancouver, ISO, and other styles

47

Mosavel, Haajierah. "Petrophysical characterization of sandstone reservoirs through boreholes E-S3, E-S5 and F-AH4 using multivariate statistical techniques and seismic facies in the Central Bredasdorp Basin." Thesis, University of the Western Cape, 2014. http://hdl.handle.net/11394/3984.

Full text

Abstract:

>Magister Scientiae - MSc
The thesis aims to determine the depositional environments, rock types and petrophysical characteristics of the reservoirs in Wells E-S3, E-S5 and F-AH4 of Area X in the Bredasdorp Basin, offshore South Africa. The three wells were studied using methods including core description, petrophysical analysis, seismic facies and multivariate statistics in order to evaluate their reservoir potential. The thesis includes digital wireline log signatures, 2D seismic data, well data and core analysis from selected depths. Based on core description, five lithofacies were identified as claystone (HM1), fine to coarse grained sandstone (HM2), very fine to medium grained sandstone (HM3), fine to medium grained sandstone (HM4) and conglomerate (HM5). Deltaic and shallow marine depositional environments were also interpreted from the core description based on the sedimentary structures and ichnofossils. The results obtained from the petrophysical analysis indicate that the sandstone reservoirs show a relatively fair to good porosity (range 13-20 %), water saturation (range 17-45 %) and a predicted permeability (range 4- 108 mD) for Wells E-S3, E-S5 andF-AH4. The seismic facies model of the study area shows five seismic facies described as parallel, variable amplitude variable continuity, semi-continuous high amplitude, divergent variable amplitude and chaotic seismic facies as well as a probable shallow marine, deltaic and submarine fan depositional system. Linking lithofacies to seismic facies maps helped to understand and predict the distribution and quality of reservoir packages in the studied wells

APA, Harvard, Vancouver, ISO, and other styles

48

Stevenson, Ian Robert. "The application of high-resolution geophysical techniques for seismic stratigraphic analysis at an outscrop scale : a study from the Namaqualand continental shelf, west coast of South Africa." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394238.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Fares, Reine. "Techniques de modélisation pour la conception des bâtiments parasismiques en tenant compte de l’interaction sol-structure." Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4103/document.

Full text

Abstract:

La conception des bâtiments selon le code sismique européen ne prend pas en compte les effets de l'interaction sol-structure (ISS). L'objectif de cette recherche est de proposer une technique de modélisation pour prendre en compte l’ISS et l'interaction structure-sol-structure (ISSS). L'approche de propagation unidirectionnelle d’une onde à trois composantes (1D-3C) est adoptée pour résoudre la réponse dynamique du sol. La technique de modélisation de propagation unidirectionnelle d'une onde à trois composantes est étendue pour des analyses d'ISS et ISSS. Un sol tridimensionnel (3D) est modélisé jusqu'à une profondeur fixée, où la réponse du sol est influencée par l’ISS et l’ISSS, et un modèle de sol 1-D est adopté pour les couches de sol plus profondes, jusqu'à l'interface sol-substrat. Le profil de sol en T est assemblé avec une ou plusieurs structures 3-D de type poteaux-poutres, à l’aide d’un modèle par éléments finis, pour prendre en compte, respectivement, l’ISS et l’ISSS dans la conception de bâtiments. La technique de modélisation 1DT-3C proposée est utilisée pour étudier les effets d’ISS et analyser l'influence d'un bâtiment proche (l'analyse d’ISSS), dans la réponse sismique des structures poteaux-poutres. Une analyse paramétrique de la réponse sismique des bâtiments en béton armé est développée et discutée pour identifier les paramètres clé du phénomène d’ISS, influençant la réponse structurelle, à introduire dans la conception de bâtiments résistants aux séismes. La variation de l'accélération maximale en haut du bâtiment avec le rapport de fréquence bâtiment / sol est tracée pour plusieurs bâtiments, chargés par un mouvement à bande étroite, excitant leur fréquence fondamentale. Dans le cas de sols et de structures à comportement linéaire, une tendance similaire est obtenue pour différents bâtiments. Cela suggère l'introduction d'un coefficient correcteur du spectre de réponse de dimensionnement pour prendre en compte l’ISS. L'analyse paramétrique est répétée en introduisant l'effet de la non-linéarité du sol et du béton armé. La réponse sismique d'un bâtiment en béton armé est estimée en tenant compte de l'effet d'un bâtiment voisin, pour un sol et des structures à comportement linéaire, dans les deux cas de charge sismique à bande étroite excitant la fréquence fondamentale du bâtiment cible et du bâtiment voisin. Cette approche permet une analyse efficace de l'interaction structure-sol-structure pour la pratique de l'ingénierie afin d'inspirer la conception d'outils pour la réduction du risque sismique et l'organisation urbaine
Building design according to European seismic code does not consider the effects of soil-structure interaction (SSI). The objective of this research is to propose a modeling technique for SSI and Structure-Soil-Structure Interaction (SSSI) analysis. The one-directional three-component (1D-3C) wave propagation approach is adopted to solve the dynamic soil response. The one-directional three-component wave propagation model is extended for SSI and SSSI analysis. A three-dimensional (3-D) soil is modeled until a fixed depth, where the soil response is influenced by SSI and SSSI, and a 1-D soil model is adopted for deeper soil layers until the soil-bedrock interface. The T-soil profile is assembled with one or more 3-D frame structures, in a finite element scheme, to consider, respectively, SSI and SSSI in building design. The proposed 1DT-3C modeling technique is used to investigate SSI effects and to analyze the influence of a nearby building (SSSI analysis), in the seismic response of frame structures. A parametric analysis of the seismic response of reinforced concrete (RC) buildings is developed and discussed to identify the key parameters of SSI phenomenon, influencing the structural response, to be introduced in earthquake resistant building design. The variation of peak acceleration at the building top with the building to soil frequency ratio is plotted for several buildings, loaded by a narrow-band motion exciting their fundamental frequency. In the case of linear behaving soil and structure, a similar trend is obtained for different buildings. This suggests the introduction of a corrective coefficient of the design response spectrum to take into account SSI. The parametric analysis is repeated introducing the effect of nonlinear behaving soil and RC. The seismic response of a RC building is estimated taking into account the effect of a nearby building, for linear behaving soil and structures, in both cases of narrow-band seismic loading exciting the fundamental frequency of the target and nearby building. This approach allows an easy analysis of structure-soil-structure interaction for engineering practice to inspire the design of seismic risk mitigation tools and urban organization

APA, Harvard, Vancouver, ISO, and other styles

50

Lebon, Grégory. "Analyse de l'endommagement des structures de génie civil : techniques de sous-structuration hybride couplées à un modèle d'endommagement anisotrope." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2011. http://tel.archives-ouvertes.fr/tel-00669997.

Full text

Abstract:

L'analyse sismique des structures de génie civil est une problématique majeure pour la sécurité des personnes et la pérennité des ouvrages. L'étude expérimentale permet de comprendre le comportement réel de la structure mais occasionne des problèmes de coût important et d'effet d'échelle souvent inévitable dû aux dimensions des structures. D'un autre côté, l'étude numérique propose une bonne approximation du comportement global mais la représentation précise des phénomènes locaux (fissuration, perte de matière, flambement, grands déplacements) dans les zones fortement endommagées est délicate et souvent insuffisante. Ce travail de thèse propose l'élaboration d'une technique de sous-structuration hybride pour coupler un modèle numérique à une plateforme expérimentale. Ainsi, la partie faiblement endommagée de la structure est modélisée numériquement tandis que la partie fortement endommagée est testée expérimentalement. Cette méthode permet de coupler le réalisme de l'expérimental avec le faible coût numérique sans toutefois perdre en précision. Après avoir élaboré une méthode de couplage hybride peu intrusive pour le code de calcul (Cast3m), un modèle d'endommagement anisotrope adapté aux chargement sismique (effet unilatéral, déformations permanentes) est développé dans le cadre de la thermodynamique des milieux continus. Afin de valider la méthode hybride, une étude expérimentale est menée sur une structure type en béton armé. La fissuration de la partie expérimentale est étudiée grâce à la corrélation d'images. Ce travail expose donc une alternative intéressante aux analyses classiques des structures importantes soumises à des sollicitations complexes.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Seismic techniques'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles