Relevant bibliographies by topics / Seismic instability

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Seismic instability'

Author: Grafiati
Published: 23 November 2024

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Journal articles on the topic "Seismic instability"

1

Bernal, Dionisio. "Instability of buildings during seismic response." Engineering Structures 20, no. 4-6 (April 1998): 496–502. http://dx.doi.org/10.1016/s0141-0296(97)00037-0.

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Rodríguez-Ochoa, Rafael, Farrokh Nadim, José M. Cepeda, Michael A. Hicks, and Zhongqiang Liu. "Hazard analysis of seismic submarine slope instability." Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards 9, no. 3 (July 3, 2015): 128–47. http://dx.doi.org/10.1080/17499518.2015.1051546.

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Zhang, Jin, Yanguo Wang, David C. Nobes, Guangnan Huang, and Hongxing Li. "Deep seismic reflection data interpretation using balanced filtering method." GEOPHYSICS 82, no. 5 (September 1, 2017): N43—N49. http://dx.doi.org/10.1190/geo2016-0061.1.

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Inverse [Formula: see text] filtering can perform energy compensation and phase correction of seismic reflection data, but it has an instability problem due to its high-pass characteristics. Although improved methods, such as gain-limited inverse [Formula: see text] filtering and stabilized inverse [Formula: see text] filtering, overcome the instability to some extent, they are not suitable for compensating deep seismic reflection events with weak energy. Focusing on the enhancement of deep seismic events, we have developed a balanced filtering method based on the ratio of the phase-compensated signal to its analytic signal counterpart. The method is insensitive to the depth of seismic records, and it can make shallow and deep seismic records visible simultaneously. When tested on synthetic data and real seismic data, compared with other methods, the balanced filtering method improves the amplitude strength of the deep reflection events and the continuity of shallow and deep seismic events effectively, which makes the deep reflection data easier to interpret.
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Du, Wen Feng, Fu Dong Yu, and Zhi Yong Zhou. "Dynamic Stability Analysis of K8 Single-Layer Latticed Shell Structures Suffered from Earthquakes." Applied Mechanics and Materials 94-96 (September 2011): 52–56. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.52.

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Aiming at the dynamic stability of the K8 single-layer latticed shell structures, it was carried out the dynamic stability analysis based on the finite element method(FEM) in this paper. The dynamic responses of the structure are calculated using the FEM and the B-R rule is applied to determine the dynamic instability critical loads. Results show that the dynamic instability is prone to take place in the K8 single-layer latticed shell structures under the severe seismic load and the dynamic instability critical seismic wave peak value is about 0.7g. The location of instability starts from the intersection between the third circular members and the radial members, then it spreads abroad until the structure collapses.
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Wadas, S. H., S. Tschache, U. Polom, and C. M. Krawczyk. "Ground instability of sinkhole areas indicated by elastic moduli and seismic attributes." Geophysical Journal International 222, no. 1 (April 20, 2020): 289–304. http://dx.doi.org/10.1093/gji/ggaa167.

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SUMMARY Elastic moduli derived from vertical seismic profiles (VSPs) and 2-D SH-wave reflection seismic profiles are used to characterize mechanical properties of rocks in sinkhole areas. VP and VS were used to calculate the Poisson’s ratio and the dynamic shear modulus. The study shows that 2-D shear wave reflection seismics is suited to depict the heterogeneities of the subsurface induced by subsurface erosion. Low shear wave velocities of ca. 120–350 m s–1 and low shear strength values between 25 and 250 MPa are identified for the subsurface erosion horizon that consists of soluble Permian evapourites and the disturbed overlying deposits. These low values are a result of cavities and fractures induced by dissolution, creating unstable zones. In compliance with the shear modulus the Poisson’s ratio derived from the VSPs shows values of 0.38–0.48 for both the presumed subsurface erosion horizon, and the deposits above. This is a further indicator of reduced underground stability. In the VSPs, anomalies of the shear modulus and the Poisson’s ratio correlate with low electrical resistivities of less than 10 Ωm from borehole logs, indicating high conductivity due to fluid content. Further investigation reveals a conversion of S-to-P wave for the subsurface erosion horizon, which is probably the result of dipping layers and an oriented fracture network. Seismic attribute analysis of the 2-D sections shows strong attenuation of high frequencies and low similarity of adjacent traces, which correlate with the degree of subsurface erosion induced wave disturbance of the underground.
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Nyland, E., and Qing Li. "Analysis of seismic instability of the Vancouver Island lithoprobe transect." Canadian Journal of Earth Sciences 23, no. 12 (December 1, 1986): 2057–67. http://dx.doi.org/10.1139/e86-190.

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Seismic refraction and reflection surveys and gravity measurements over Vancouver Island, British Columbia, Canada, can constrain a finite-element model of the geodynamics of the subduction zone. Stress estimates obtained from this model have been combined with rock failure criteria to yield a probability measure of seismic risk that assumes seismic events start from a dilute distribution of Griffith cracks. The results are in agreement with the observed seismicity and lead to the suggestion that the dominant mechanism of this oceanic plate subduction zone is gravitational ridge push and mantle convection.
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Cui, Fang Peng, Yue Ping Yin, Rui Lin Hu, and Jin Qing Yu. "Failure Mechanisms of the Landslides Triggered by the 2008 Wenchuan Earthquake, China." Advanced Materials Research 594-597 (November 2012): 1864–68. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.1864.

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Taking the landslides triggered by the 2008 Wenchuan Earthquake as examples, their dynamic responses with different epicenter distances due to single and combined action with regionality and spatial heterogeneity of the Primary and Secondary waves were simulated by applying the Universal Distinct Element Code software. The results shows that the slope suffered from the combined action between P and S waves appears instability prior to the slope under single action of P wave. With the epicenter distance increasing, the key controlling factor resulting in the slope failure varies from the combined seismic action between P and S waves to the single seismic action of the P wave. As for the formation mechanism of slope instability, coupled action between the vertical and horizontal seismic forces results in the slope dynamic failure with key action varying from the vertical to the horizontal one. Finally, the initial instability originates always at slope shoulder due to the peak ground acceleration amplification effect and the variation trend of the slope mechanical parameters on its fracturing of the seismic action.
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Orlando, Luciana. "Multidisciplinary Approach to a Recovery Plan of Historical Buildings." International Journal of Geophysics 2011 (2011): 1–12. http://dx.doi.org/10.1155/2011/258043.

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The paper emphasizes the advantages of employing multiple data techniques—geology, GPS, surveys of cracking, boreholes, seismic refraction and electrical resistivity tomography—to image the shallow stratigraphy and hypothesize the cause of instability of an urban area. The study is focused on the joint interpretation of the crack pattern, topographic monitoring and the features of the underground, to define the area affected by instability and the direction of ground motion with the objective to advance a hypothesis on the cause of the instability of the area and to depict the main features. Borehole stratigraphies for a univocal interpretation of the lithology of electrical and seismic data and electrical resistivity tomography to constrain the interpretation of the lateral velocity variations and thickness of seismic bedrock were used. The geophysical surveys reveals to be complementary in the depicting of underground features. The study is approached at small and medium scale.
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Taurbekova, A. Ә., О. Zh Mamyrbaev, K. Zh Doshtaev, and Т. К. Eginbaykyzy. "HYDRODYNAMIC INSTABILITY MECHANISM PROCESS FOR ASSESSMENT SEISMIC ACTIVITY." SERIES PHYSICO-MATHEMATICAL 4, no. 348 (December 28, 2023): 268–89. http://dx.doi.org/10.32014/2023.2518-1726.234.

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Xue, Zongan, Yanyan Ma, Shengjian Wang, Huayu Hu, and Qingqing Li. "A Multi-Task Learning Framework of Stable Q-Compensated Reverse Time Migration Based on Fractional Viscoacoustic Wave Equation." Fractal and Fractional 7, no. 12 (December 10, 2023): 874. http://dx.doi.org/10.3390/fractalfract7120874.

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Q-compensated reverse time migration (Q-RTM) is a crucial technique in seismic imaging. However, stability is a prominent concern due to the exponential increase in high-frequency ambient noise during seismic wavefield propagation. The two primary strategies for mitigating instability in Q-RTM are regularization and low-pass filtering. Q-RTM instability can be addressed through regularization. However, determining the appropriate regularization parameters is often an experimental process, leading to challenges in accurately recovering the wavefield. Another approach to control instability is low-pass filtering. Nevertheless, selecting the cutoff frequency for different Q values is a complex task. In situations with low signal-to-noise ratios (SNRs) in seismic data, using low-pass filtering can make Q-RTM highly unstable. The need for a small cutoff frequency for stability can result in a significant loss of high-frequency signals. In this study, we propose a multi-task learning (MTL) framework that leverages data-driven concepts to address the issue of amplitude attenuation in seismic records, particularly when dealing with instability during the Q-RTM (reverse time migration with Q-attenuation) process. Our innovative framework is executed using a convolutional neural network. This network has the capability to both predict and compensate for the missing high-frequency components caused by Q-effects while simultaneously reconstructing the low-frequency information present in seismograms. This approach helps mitigate overwhelming instability phenomena and enhances the overall generalization capacity of the model. Numerical examples demonstrate that our Q-RTM results closely align with the reference images, indicating the effectiveness of our proposed MTL frequency-extension method. This method effectively compensates for the attenuation of high-frequency signals and mitigates the instability issues associated with the traditional Q-RTM process.
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Dissertations / Theses on the topic "Seismic instability"

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Sepúlveda, Sergio Andrés. "The effect of topographic amplification on seismic rock slope instability." Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405772.

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Okubo, Paul G. "Experimental and numerical model studies of frictional instability seismic sources." Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/54952.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1986.
Microfiche copy available in Archives and Science
Bibliography: leaves 157-162.
Paul G. Okubo.
Ph.D.
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Nicolosi, Massimo. "Seismic analysis of inclined shallow granular deposits." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1158.

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In the last decades many attempts for understanding the cyclic and dynamic behaviour of soft soils have been devoted by the scientific community. The aim of this thesis consists to investigate the mechanical response of two granular material (Hostun and Toyoura sand) in cyclic/dynamic conditions. In this paper some relationships between permanent displacement, evaluated by means of the code VIBRAZIONE and the Newmark method, and earthquake parameters, such as critical acceleration ratio, Arias Intensity and Destructive Power, have been investigated.
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Balal, Onur. "Probabilistic Seismic Hazard Assessment For Earthquake Induced Landslides." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615453/index.pdf.

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Earthquake-induced slope instability is one of the major sources of earthquake hazards in near fault regions. Simplified tools, such as Newmark&rsquo
s Sliding Block (NSB) Analysis are widely used to represent the stability of a slope under earthquake shaking. The outcome of this analogy is the slope displacement where larger displacement values indicate higher seismic slope instability risk. Recent studies in the literature propose empirical models between the slope displacement and single or multiple ground motion intensity measures such as peak ground acceleration or Arias intensity. These correlations are based on the analysis of large datasets from global ground motion recording database (PEER NGA-W1 Database). Ground motions from earthquakes occurred in Turkey are poorly represented in NGA-W1 database since corrected and processed data from Turkey was not available until recently. The objective of this study is to evaluate the compatibility of available NSB displacement prediction models for the Probabilistic Seismic Hazard Assessment (PSHA) applications in Turkey using a comprehensive dataset of ground motions recorded during earthquakes occurred in Turkey. Then the application of selected NSB displacement prediction model in a vector-valued PSHA framework is demonstrated with the explanations of seismic source characterization, ground motion prediction models and ground motion intensity measure correlation coefficients. The results of the study is presented in terms of hazard curves and a comparison is made with a case history in Asarsuyu Region where seismically induced landslides (Bakacak Landslides) had taken place during 1999 Dü
zce Earthquake.
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Atlayan, Ozgur. "Effect of Viscous Fluid Dampers on Steel Moment Frame Designed for Strength and Hybrid Steel Moment Frame Design." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/32318.

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The first purpose of this research is to investigate the effect of added viscous fluid dampers on a nine story special steel moment frame designed for strength in Seattle. At the initial stages of the work, knowing the fact that moment frames are almost always controlled by drift, it was thought that two different moment frames, controlled by strength or controlled by drift (stiffness), could be designed in Seattle and the effect of additional dampers on the structural behavior of the strength controlled design could be studied.

However, since ASCE 7 permits determining the elastic drifts by using the seismic design forces based on the computed fundamental period of the structure, without the upper limit (CuTa), the strength controlled design satisfied the drift limit requirements of ASCE 7. Although the strength controlled design meets the drift requirements, the stability checks of both ASCE 7 and the AISC Seismic Design Manual were not satisfied. Thus, the strength controlled frame was redesigned to meet the stability requirements, and the process is called stability controlled design.

By adding supplemental dampers to the strength controlled design, it was expected that the seismic drift would be controlled and a better structural behavior would be obtained in terms of dynamic stability. Incrementral Dynamic Analysis (IDA) was implemented to investigate the benefits of the dampers on the structural behavior. Using ten different earthquakes scaled up to a maximum target multiplier two, with ten increments, damage measures such as interstory drift, residual displacement, IDA dispersion, base shear, and roof displacement were studied. Using IDA dispersion, the effect of dampers on dynamic instability was also investigated in this study.

As a result, it was found that as the damping of the structure increases with the help of added dampers, the structural response gets better. Maximum and residual roof displacements, interstory drifts, and IDA dispersion decreases with increasing damping. In addition, by using supplemental damping, most of the collapses that occur for the inherently damped frames are prevented.

The second purpose of this research is to develop an improved â Hybridâ moment frame without added damping but by controlling the inelastic behavior. Hybrid Frames were designed as the combination of three different moment frames: Special, Intermediate and Ordinary Moment Frames (SMF, IMF, OMF). The design procedure of each bay, which corresponds to different moment frame systems, follows the rules of the related moment frame for that bay. By varying the plastic hinge capacities across the same level stories, four different Hybrid Frame designs were obtained. Nonlinear static pushover analysis was applied to these frames, and as expected, the more reduction in the plastic capacity of the Hybrid Frame, the earlier the pushover curve starts yielding and the later the negative post yield stiffness of the pushover curve was reached. It was observed that the effect of early plastic hinge forming in the frame, which caused inelastic hysteretic damping, and the relatively late formation of negative post yield stiffness resulted in a better dynamic behavior.

As a result of the IDA studies, as the frames become more â hybridâ , the residual displacements decrease significantly and then collapses are even prevented. This is considered as the positive effect of reaching the negative post yield stiffness late. The residual displacement was reduced for low intensity gentle earthquakes. The ductility demand IDA study proves that as the frames become more hybrid, the ductility demand increases for the special detailing frame, where plastic capacity was reduced, and decreases for the ordinary detailing frame, where the plastic capacity was increased. The Hybrid Frame system is expected to perform better than the traditional special moment frame, and to be more economical than the special moment frame because of the limited amount of special detailing.
Master of Science

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Rahmanov, Ogtay Rasim. "Sequence stratigraphy of the late Pleistocene - Holocene deposits on the northwestern margin of the South Caspian Basin." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1185.

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Interpretation of 900 km of a closely spaced grid of high-resolution seismic profiles over the northwestern margin of South Caspian Basin (SCB) allows recognition and study of six late Pleistocene - Holocene depositional sequences. Sequence stratigraphy analysis of sedimentary strata from 117,000 years B.P. to present led to the identification of a highstand systems tract, two transgressive systems tracts and six lowstand systems tracts. Each systems tract is characterized by specific seismic facies. Diverse depositional processes on the northwestern margin of the SCB are suggested by the thirteen seismic facies patterns recognized in the study area. Two distinct progradational complexes were interpreted within Sequence III and Sequences IV and V in the northeastern and northwestern parts of the study area, respectively. Stratigraphic interpretation of the sequences provided important information on parameters that control depositional architectures, such as lake level fluctuations, tectonic dynamics, and sediment supply. High sedimentation rates combined with a series of high-frequency and high-amplitude lake-level fluctuations, abrupt changes at the shelf edge, abnormally high formation pressure, and high tectonic activity during Quaternary time resulted in the development of a variety of complex geologic drilling hazards. I distinguished three types of hazards as a result of this study: mud volcanoes, sediment instability, and shallow gas. The 2D high-resolution seismic dataset from the northwestern margin of the SCB allowed more detailed seismic sequence stratigraphic analysis in the study area than has previously been attempted. In particular, it has a clear application in deciphering sediment supply and relative lake level changes as well as tectonic relationship of the northwestern shelf margin of the SCB. Results of this work led us towards better understanding of recent depositional history, improved our knowledge of the nature of the basin tectonics, climate history and styles of and controls on sedimentation processes within a sequence stratigraphic framework during the late Pleistocene-Holocene time.
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Biscans, Sébastien. "Optimization of the Advanced LIGO gravitational-wave detectors duty cycle by reduction of parametric instabilities and environmental impacts." Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1019/document.

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Le projet LIGO a pour but la détection et l'étude d'ondes gravitationnelles via un réseau de détecteurs. LIGO possède deux détecteurs d'architecture et de fonctionnement identiques, situés aux États-Unis. Chaque détecteur est une version améliorée d'un interféromètre de Michelson avec des bras optiques de 4 km de long. Ces interféromètres ont observé une onde gravitationnelle pour la première fois en septembre 2015, suivi par cinq autres détections à ce jour. Ces détections marquent le début d™une nouvelle ère pour l'astrophysique, en liaison étroite avec la physique des trous noirs et des étoiles à neutrons. Depuis, un grand nombre d'activités sont en développement pour perfectionner les interféromètres. Cette thèse a pour objectif d'améliorer le temps de service des détecteurs, en répondant en particulier à deux problématiques majeures : le problème des impacts environnementaux, et notamment celui des tremblements de terre, ainsi que le problème lié à des couplages opto-mécaniques instables dans les cavités optiques, appelés instabilités paramétriques. Les stratégies de contrôle et les outils développés pour résoudre ces problématiques sont présentés. Les résultats prémilinaires montrent une réduction du temps d'arrêt généré par les tremblements de terre d'environ 40%. De plus, le dispositif ‚Acoustic Mode Damper™ développé pendant la thèse devrait complètement résoudre le problème des instabilités paramétriques pour LIGO. En conclusion, il sera démontré en quoi les problématiques résolues ont permis d'améliorer le cycle de service des détecteurs de LIGO de 4,6%, ce qui correspond à une augmentation du nombre d'ondes gravitationnelles détectées par an de 14%
The LIGO project is a large-scale physics experiment the goal of which is to detect and study gravitational waves of astrophysical origin. It is composed of two instruments identical in design, located in the United States. The two instruments are specialized versions of a Michelson interferometer with 4km-long arms. They observed a gravitational-wave signal for the first time in September 2015 from the merger of two stellar-mass black holes. This is the first direct detection of a gravitational wave and the first direct observation of a binary black hole merger. Five more detections from binary black hole mergers and neutron stars merger have been reported to date, marking the beginning of a new era in astrophysics. As a result of these detections, many activities are in progress to improve the duty cycle and sensitivity of the detectors. This thesis addresses two major issues limiting the duty cycle of the LIGO detectors: environmental impacts, especially earthquakes, and the issue of unstable opto-mechanical couplings in the cavities, referred to as parametric instabilities. The control strategies and tools developed to tackle these issues are presented. Early results have shown a downtime reduction during earthquakes of ~40% at one of the LIGO sites. Moreover, the electro-mechanical device called ‚Acoustic Mode Damper™ designed and tested during the thesis should completely solve the issue of parametric instabilities for LIGO. In conclusion, we will show that the problems tackled in this thesis improved the overall duty cycle of LIGO by 4.6%, which corresponds to an increase of the gravitational-wave detection rate by 14%
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Bagur, Laura. "Modeling fluid injection effects in dynamic fault rupture using Fast Boundary Element Methods." Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. http://www.theses.fr/2024IPPAE010.

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Les tremblements de terre d'origine naturelle ou anthropique provoquent d'importants dégâts humains et matériels. Dans les deux cas, la présence de fluides interstitiels influe sur le déclenchement des instabilités sismiques. Une nouvelle question d'actualité dans la communauté est de montrer que l'instabilité sismique peut être atténuée par un contrôle actif de la pression des fluides. Dans ce travail, nous étudions la capacité des méthodes d'éléments de frontière rapides (Fast BEMs) à fournir un solveur robuste multi-physique à grande échelle nécessaire à la modélisation des processus sismiques, de la sismicité induite et de leur atténuation.Dans une première partie, un solveur BEM rapide avec différents algorithmes d'intégration temporelle est utilisé. Nous évaluons les performances de diverses méthodes à pas de temps adaptatif sur la base de problèmes de cycles sismiques 2D usuels pour les failles planes.Nous proposons une solution asismique analytique pour effectuer des études de convergence et fournir une comparaison rigoureuse des capacités des différentes méthodes en plus des problèmes de cycles sismiques de référence testés.Nous montrons qu'une méthode hybride prédiction-correction / Runge-Kutta à pas de temps adaptatif permet non seulement une résolution précise mais aussi d'incorporer à la fois les effets inertiels et les couplages hydro-mécaniques dans les simulations de rupture dynamique de faille.Dans une deuxième partie, une fois les outils numériques développés pour des configurations standards, notre objectif est de prendre en compte les effets de l'injection de fluide sur le glissement sismique. Nous choisissons le cadre poroélastodynamique pour incorporer les effets de l'injection sur l'instabilité sismique. Un modèle poroélastodynamique complet nécessiterait des coûts de calcul ou des approximations non négligeables. Nous justifions rigoureusement quels effets fluides prédominants sont en jeu lors d'un tremblement de Terre ou d'un cycle sismique. Pour cela, nous effectuons une analyse dimensionnelle des équations, et illustrons les résultats en utilisant un problème de poroelastodynamique 1D simplifié. Plus précisément, nous montrons qu'à l'échelle de temps de l'instabilité sismique, les effets inertiels sont prédominants alors qu'une combinaison de la diffusion du fluide et de la déformation élastique de la matrice solide due à la variation de la pression interstitielle devrait être privilégiée à l'échelle de temps du cycle sismique, au lieu du modèle de diffusion principalement utilisé dans la littérature
Earthquakes due to either natural or anthropogenic sources cause important human and material damage. In both cases, the presence of pore fluids influences the triggering of seismic instabilities.A new and timely question in the community is to show that the earthquake instability could be mitigated by active control of the fluid pressure. In this work, we study the ability of Fast Boundary Element Methods (Fast BEMs) to provide a multi-physic large-scale robust solver required for modeling earthquake processes, human induced seismicity and their mitigation.In a first part, a Fast BEM solver with different temporal integration algorithms is used. We assess the performances of various possible adaptive time-step methods on the basis of 2D seismic cycle benchmarks available for planar faults. We design an analytical aseismic solution to perform convergence studies and provide a rigorous comparison of the capacities of the different solving methods in addition to the seismic cycles benchmarks tested. We show that a hybrid prediction-correction / adaptive time-step Runge-Kutta method allows not only for an accurate solving but also to incorporate both inertial effects and hydro-mechanical couplings in dynamic fault rupture simulations.In a second part, once the numerical tools are developed for standard fault configurations, our objective is to take into account fluid injection effects on the seismic slip. We choose the poroelastodynamic framework to incorporate injection effects on the earthquake instability. A complete poroelastodynamic model would require non-negligible computational costs or approximations. We justify rigorously which predominant fluid effects are at stake during an earthquake or a seismic cycle. To this aim, we perform a dimensional analysis of the equations, and illustrate the results using a simplified 1D poroelastodynamic problem. We formally show that at the timescale of the earthquake instability, inertial effects are predominant whereas a combination of diffusion and elastic deformation due to pore pressure change should be privileged at the timescale of the seismic cycle, instead of the diffusion model mainly used in the literature
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Spears, Paul Wesley. "Parameters Influencing Seismic Structural Collapse with Emphasis on Vertical Accelerations and the Possible Related Risks for New and Existing Structures in the Central and Eastern United States." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/42793.

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This thesis presents the results of basically two separate studies. The first study involved identifying structural and earthquake parameters that influenced seismic structural collapse. The parameter study involved nonlinear dynamic analyses using single-degree-of-freedom (SDOF) bilinear models. Four parameters were associated with the SDOF models â the lateral stiffness, the post-yield stiffness ratio, the yield strength, and the stability ratio (P-Delta effects). Then, three parameters were associated with the ground motions â the records themselves, the lateral ground motion scales, and the vertical ground motion scales.

From the parameter study, it was found that the post-yield stiffness ratio augmented by P-Delta effects (rp) in conjunction with the ductility demand was the best predictor of collapse. These two quantities include all four structural parameters and the seismic displacement demands. It was also discovered in the parameter study that vertical accelerations did not significantly influence lateral displacements unless a given combination of model and earthquake parameters was altered such that the model was on the verge of collapsing.

The second study involved Incremental Dynamic Analysis (IDA) using bilinear SDOF models representative of low rise buildings in both the Western United States (WUS) and the Central and Eastern United States (CEUS). Models were created that represented three, five, seven, and nine story buildings. Five sites from both the WUS and CEUS were used. Four different damage measures were used to assess the performance of the buildings. The IDA study was primarily interested in the response of the structures between the earthquake intensities that have a 10 percent probability of occurring in 50 years (10/50) and 2 percent probability of occurring in 50 years (2/50).

The results showed that all structures could be in danger of severe damage and possible collapse, depending on which damage measure and which earthquake was used. It is important to note, though, that the aforementioned is based on a damage-based collapse rule. The damage-based rule results were highly variable.

Using an intensity-based collapse rule, proved to be more consistent. Due to the nature of the bilinear models, only those structures with negative rp values ever collapsed using an intensity-based collapse rule. Most of the WUS models had positive rp values and many of the CEUS models had negative rp values. While many of the CEUS structures had negative rp values, which made them prone to collapse, most of the CEUS structures analyzed did not collapse at the 2/50 intensity. The reason was that the periods of the CEUS models were much longer than the approximate periods that were required to determine the strengths. Consequently, the strength capacity of most of the CEUS models was much greater than the seismic strength demands. While many of the CEUS models did have sudden collapses due to the large negative rp values, the collapses happened at intensities that were generally much higher than the 2/50 event.

In the IDA, it was also shown that vertical accelerations can significantly affect the ductility demands of a model with a negative rp post-yield stiffness ratio as the earthquake intensity approaches the collapse intensity. Since IDA is concerned with establishing collapse limit states, it seems that the most accurate collapse assessments would include vertical accelerations.
Master of Science

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Colón, Sirel. "La sédimentation récente sur la marge nord-vénézuelienne (littoral central) : enregistrement superposé des instabilités d’origine climatique et des conséquences de l’activité sismique (glissements, tsunamis)." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAU019/document.

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La bordure septentrionale du Vénézuela (bordure méridionale de la Plaque Caraïbe) correspond pour l’essentiel à un relais de grandes failles décrochantes actives, génératrice d’une marge escarpée et accidentée (Sud de la Mer Caraïbe, Fosse et Golfe de Cariaco, Fig. 1). Cette région est donc exposée à trois sources d’aléas naturels : 1) séismes et effets directs, 2) tsunamis (liés à ces failles, à l’activité plus lointaine des Arcs Antillais, ou à des glissements sous-marins), 3) glissements et coulées aériens, parfois liés à des événements climatiques brutaux (cf. flash flood de Vargas, Décembre 1999). Le deuxième et le troisième type de phénomènes affectent directement la sédimentation soit marine (littoral et plateforme) soit lagunaire ou lacustre. Par ailleurs, les dernières variations globales (rapides) du niveau marin ont subdivisé et structuré l’empilement sédimentaire.La partie récente de ces dépôts (env. 150 000 à 200 000 ans) a fait l’objet de deux campagnes préliminaires d’imagerie sismique à haute résolution, la première consacrée à la partie orientale (Golfe de Cariaco; Audemard et al., 2007 ; Van Daele et al., 2010) et la seconde au littoral central (entre Cabo Codera et la Golfe Triste, Fig. 2). Cette seconde mission sera complétée par une nouvelle acquisition d’imagerie et la prise de carottes courtes en mer et dans les lagunes côtières. L'interprétation des sections sismiques et l'analyse sédimentologique des carottes sera utilisé pour ce travail de thèse avec un double but : 1) reconstituer l’évolution générale de la sédimentation sur la marge, et l’influence des changements environnementaux globaux, 2) connaître la distribution géographique et dans le temps (pour une période d’au moins 100 000 ans) des phénomènes catastrophiques majeurs (séismes, tsunamis, flash floods) qui se sont intercalés dans cette sédimentation. L’impact possible de la superposition de phénomènes externes et sismo-tectoniques (cf. récent séismes de Tucacas pendant un épisode pluvieux) et la localisation des zones à risques pour les tsunamis, seront modélisés et discutés
The northern border of Venezuela (southern border of the Caribbean Plate) corresponds essentially to a relay of large active strike-slip faults, generating a steep and rugged margin (South of the Caribbean Sea, Pit and Gulf of Cariaco, Fig. 1). This region is therefore exposed to three sources of natural hazards: 1) earthquakes and direct effects, 2) tsunamis (related to these faults, to the more distant activity of the West Indies bows, or to submarine landslides), 3) slips and airflows, sometimes linked to sudden climatic events (see Vargas flash flood, December 1999). The second and third types of phenomena directly affect sedimentation, whether marine (littoral and platform), lagoon or lacustrine. In addition, the latest global (fast) changes in the sea level have subdivided and structured the sedimentary stack.The recent part of these deposits (about 150 000 to 200 000 years ago) was the subject of two preliminary high resolution seismic imaging campaigns, the first devoted to the eastern part (Gulf of Cariaco, Audemard et al. 2007, Van Daele et al., 2010) and the second at the central coast (between Cabo Codera and the Sad Gulf, Fig. 2). This second mission will be complemented by a new imaging acquisition and the taking of short cores at sea and in coastal lagoons. The interpretation of the seismic sections and the sedimentological analysis of the cores will be used for this work of thesis with a double aim: 1) to reconstruct the general evolution of the sedimentation on the margin, and the influence of the global environmental changes, 2) to know the geographical distribution and over time (for a period of at least 100,000 years) major catastrophic phenomena (earthquakes, tsunamis, flash floods) that have interbedded in this sedimentation. The possible impact of the superposition of external and seismo-tectonic phenomena (see the recent Tucacas earthquakes during a rainy episode) and the location of tsunami risk areas will be modeled and discussed
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Books on the topic "Seismic instability"

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Geological Survey (U.S.) and United States. Minerals Management Service, eds. Seismic structure and stratigraphy of the New England Continental Slope and the evidence for slope instability. [Reston, Va.?]: U.S. Dept. of the Interior, Geological Survey, 1986.

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Geological Survey (U.S.) and United States. Minerals Management Service., eds. Seismic structure and stratigraphy of the New England Continental Slope and the evidence for slope instability. [Reston, Va.?]: U.S. Dept. of the Interior, Geological Survey, 1986.

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Nudo, Raffaele, ed. Lezioni dai terremoti: fonti di vulnerabilità, nuove strategie progettuali, sviluppi normativi. Florence: Firenze University Press, 2012. http://dx.doi.org/10.36253/978-88-6655-072-3.

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This book is a collection of the academic contributions presented at the conference entitled "Lessons from earthquakes: sources of vulnerability, new design strategies and regulatory developments" which was held at Chianciano Terme on 8 October 2010. The issues addressed are central to Seismic Engineering and comprise a wide range of arguments on both consolidated subjects and innovative aspects in the sector. Among these, appropriate attention is devoted to: analysis of the structural instability revealed on the occasion of seismic events and the lessons that can be drawn from the same; the procedures of assessment of the existing buildings, starting from the phase of monitoring and diagnostics through to the definition of the most opportune intervention techniques; the use of composite materials and alternative methods of seismic protection; non-linear field modelling relating to regular and non-regular structures; and finally, the development of the methods of calculation that have characterised the evolution of the regulatory codes.
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Crespellani, Teresa, ed. Terremoto e ricerca. Florence: Firenze University Press, 2008. http://dx.doi.org/10.36253/978-88-8453-819-2.

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The profound cultural transformation that has taken place in Italian seismic studies in the last ten years is distinguished by the growing interest in the problem of assessing the effects of earthquakes linked to local conditions, and in the related issue of a precise definition of the properties of the soil in the sphere of the dynamic and cyclical stresses induced by seismic actions. Despite the profound awareness of the extent to which the nature of the soil contributes to the destructive effects of earthquakes, we are still a long way from the possibility of a realistic forecast of the seismic behaviour of the Italian soils. This is because the identification of the dynamic properties calls for experimental equipment that is technologically complex and costly as well as lengthy observation and qualified personnel. The rare experimental data that have been acquired to date hence represent a fundamental element for scientific reflection. This book has been conceived with a view to setting at the disposal of a broader public the results of the tests conducted on site and in the laboratory on the soil of certain significant seismic areas using the dynamic-type apparatus of the Geotechnical Laboratory of the Department of Civil and Environmental Engineering (DICeA) of the University of Florence. It presents a selection of the works of the Geotechnical section of the DICeA that have been published in various specialist international and national ambits. These studies were largely launched following the seismic sequence in Umbria and the Marches, in collaboration with several Regional Authorities and Research Institutes for the reduction of the seismic risk in Italy (GNDT, IRRS, INGV). In addition to the experimental techniques and the results obtained, the models and the geotechnical procedures adopted for assessing the effects of site and soil instability in certain specific deposits of the Italian territory are also expounded.
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Book chapters on the topic "Seismic instability"

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Pandey, Om Prakash. "Seismic Instability and Major Intraplate Earthquakes." In Society of Earth Scientists Series, 247–90. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-40597-7_8.

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Yan, Chunli, Jin Tu, Hui Liang, Shengshan Guo, and Deyu Li. "Seismic Safety Evaluation of a High Arch Dam-Foundation Coupling System." In Lecture Notes in Civil Engineering, 186–96. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-9184-2_17.

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AbstractThe seismic safety evaluation of the dam is performed based on either dam strength failure or dam abutment instability failure according to the traditional deterministic methods and concepts in the current code. However, these two failure modes are interactive and inseparable, considering only one failure mode under a strong earthquake fails to fully reflect the actual seismic performance of high arch dams. To develop a more realistic seismic safety evaluation framework for high arch dams, this paper constructs a finite element analysis model that considers the coupling of dam strength failure and dam abutment instability failure. The nonlinear dynamic response analysis of the high arch dam-foundation coupling system is conducted using the seismic overload analysis method. Different performance evaluation indexes, such as damage depth-thickness ratio, sliding area ratio, and the residual displacement of the dam crest relative to the dam bottom in the stream direction, are proposed. The performance evaluation criteria and ultimate seismic capacity are defined and quantitatively assessed. The results indicate that 2.0 times the horizontal PGA can be considered the ultimate seismic capacity of the high arch dam-foundation coupling system, providing a reliable scientific basis for seismic safety evaluation of high arch dams.
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Uang, C. M., and C. C. Fan. "Cyclic instability of steel moment connections with reduced beam sections." In Behaviour of Steel Structures in Seismic Areas, 747–53. London: CRC Press, 2021. http://dx.doi.org/10.1201/9781003211198-102.

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Bousmaha, Mohammed, Mohamed Bensoula, Renaud Toussaint, Hanifi Missoum, and Karim Bendani. "Mechanical Instability of Sandy Soils Under Seismic Effect (Algeria)." In Recent Advances in Geo-Environmental Engineering, Geomechanics and Geotechnics, and Geohazards, 201–3. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-01665-4_47.

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Towhata, Ikuo. "Coseismic and Post-seismic Slope Instability Along Existing Faults." In Proceedings of the 4th International Conference on Performance Based Design in Earthquake Geotechnical Engineering (Beijing 2022), 195–213. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-11898-2_10.

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Hu, Caifeng, Feng Xiong, and Xiangkai Zhang. "The Dynamic Response Characteristics of the Slopes with Different Slope Morphology Under the Seismic Wave Action." In Lecture Notes in Civil Engineering, 391–403. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-5814-2_35.

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AbstractThe seismic landslides are common natural hazards in the mountainous areas, and they can cause a large number of casualties and property losses directly. The dynamic response characteristics of slope under the action of the seismic wave are the primary problem in evaluating the slope seismic stability. In this paper, the research is carried out on the effects of slope angle, morphology, and seismic wave frequency on the slope dynamic responses. Firstly, the slopes with different shapes (straight, concave, and convex slopes) are modeled. Secondly, the slope acceleration amplification factors and shear strain increment are investigated and analyzed. Finally, the dynamic response mechanisms are revealed using the ray analysis method. The results show that the acceleration response of each part of the slope is different for different frequencies, and the value of the amplification factor at the slope surface center is greater than that at the slope top. Slope morphology has significant effects on the dynamic response of the slope, and the slope surface centroid amplification factors change with different slope morphology. Slope angle has prominent impacts on the slope dynamic responses; the amplification factor is greatest at the slope angle of 30°. This study deepens the understanding of the slope seismic dynamic responses, which is vital for predicting slope instability and disaster reduction.
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Tiwari, Ram Chandra, and Netra Prakash Bhandary. "Application of Spectral Element Method (SEM) in Slope Instability Analysis." In Progress in Landslide Research and Technology, Volume 1 Issue 1, 2022, 163–74. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-16898-7_11.

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AbstractSpectral element framework for slope instability analysis includes Spectral Element Method (SEM) formulation, system requirements for serial and parallel computations, model preparation with hexahedral meshing in Cubit or Trelis, meshing and mapping technique (h- and p-refinement techniques) according to SEM, applying boundary conditions for 2D and 3D, defining inputs for material model, ground water table, seismic loading as well as processing and visualizing the results in Tecplot and ParaView. Within this framework, the safety factor in slope stability is computed and visualized with greater spectral accuracy and stability.
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Xu, Bin, and Rui Pang. "Stochastic Seismic Analysis and Performance Safety Evaluation for Slope Stability of High CFRDs." In Hydroscience and Engineering, 133–61. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-7198-1_7.

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AbstractNumerous engineering cases (Guan, Sci China Ser e: Technol Sci 52:820–834, 2009; Liu et al., J Perform Constr Facil 29:04,014,129, 2015), dynamic numerical analysis (Zou et al., Comput Geotech 49:111–122, 2013; Uddin, Comput Struct 72:409–421, 1999) and dynamic physical model tests (Zhu et al., Journal of Harbin Institute of Technology 18:132–138, 2011; Liu et al., Soil Dyn Earthq Eng 82:11–23, 2016) demonstrated that the instability of dam slopes is a major engineering concern for high CFRDs under earthquake excitation. It is explicitly mandated that seismic stability calculations for earth-rock dams should be included in seismic analysis in China's Hydraulic Seismic Design Code (NB 35047–2015). The comprehensive evaluation of slope stability is further specified to consider the factors such as the position, depth, and extent of the slip surface, as well as the duration and magnitude of stability index exceeding limits.
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Alexander, David. "“Extraordinary, and terrifying metamorphosis” — on the seismic causes of slope instability." In History of Geomorphology, 127–50. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-011-9828-8_7.

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Irvan, Sophian, Febri Hirnawan, Zufialdi Zakaria, and Febriwan Mohamad. "The Effect of Vibration Generated by 2D-Seismic Survey Operation on Natural Slope Instability." In Engineering Geology for Society and Territory - Volume 2, 731–35. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-09057-3_123.

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Conference papers on the topic "Seismic instability"

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Cheng, Franklin Y., and Jeng-Fuh Ger. "Instability and Collapse Behavior of a Seismic Structure." In ASME 1991 Design Technical Conferences. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/detc1991-0337.

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Abstract The collapse behavior of a 22-story steel building during the September 19, 1985 Mexico earthquake is investigated by studying hysteretic behavior, ductility factors of individual structural components, and overall instability of the building. The hysteresis models for truss-type girders, bracing members, and box columns to be used in the inelastic analysis of this building are developed. A series of inelastic analyses have been performed for the building by using the multicomponent seismic input of actual Mexico City earthquake records. It was found that the structural response exceeds the original design ductility of this building because most girders in the building have suffered large ductilities. Due to the load redistribut-ion effects from the ductile-failed girders, local bucklings developed at many columns on floors 2, 3, and 4. Therefore, most columns on floors 2 through 4 lost their load carrying capacities and rigidities which then caused the building to tilt and rotate. As a result, more columns on floors 5 through 7 developed local buckling and more bracing members buckled. It is believed that ductile failures of girders combined with the local bucklings of columns in the lower part of the building resulted in significant story drift, building tilt, P-A effect, and the failure mechanism.
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Kobayashi, Nobuyuki, Keisaku Kitada, and Yoshiki Sugawara. "Parametric Instability in Metallic Bellows Subjected to Seismic Excitation." In ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-28157.

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This paper investigates the parametric instability of a metallic bellows filled with fluid and subjected to the variance of dynamic internal pressure due to an earthquake. The axial stiffness of the bellows varies due to the variation in internal static fluid pressure, and this stiffness variation induces a parametric instability in the bellows. A finite element model describing a bellows connected to a pipe is developed to examine the question of whether parametric instability is excited in such bellows by earthquake motion, which is not the harmonic vibration. Numerical simulations and experiments were carried out using the acceleration recorded by past recorded actual earthquakes. We find that indeed parametric instability may appear in the bellows when the natural frequency of the pipe is close to the predominant frequency component of the earthquake, though the earthquake motion is not harmonic.
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OGUNRO, VINCENT O., MUTIU G. AYOOLA, HILARY I. INYANG, and GUSTAVO B. MENEZES. "GEOSYNTHETICS IN MITIGATING SEISMIC-INDUCED WASTE CONTAINMENT COVER INSTABILITY." In Proceedings of the International Conference. WORLD SCIENTIFIC, 2005. http://dx.doi.org/10.1142/9789812701602_0054.

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Knappett, Jonathan A., and S. P. Gopal Madabhushi. "Modelling of Liquefaction-Induced Instability in Pile Groups." In Workshop on Seismic Performance and Simulation of Pile Foundations in Liquefied and Laterally Spreading Ground. Reston, VA: American Society of Civil Engineers, 2005. http://dx.doi.org/10.1061/40822(184)21.

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Fujita, Katsuhisa, Taisuke Nosaka, and Tomohiro Ito. "Dynamic Instability of a Cylindrical Shell Structure Subjected to Horizontal and Vertical Excitations Simultaneously." In ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-2910.

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Many structures such as support columns such as those for elevated expressways and towers tend to become larger and more flexible recently, thus the buckling or collapse of these structures is considered to easily occur than ever due to huge earthquakes. Actually, in the Hyogo-ken Nambu earthquake in Japan, buckling phenomena of tall support columns were observed every-where. Therefore, the evaluation technology on the dynamic stability is very important in order to ensure the seismic design reliability for these structures. The authors have ever studied the effects of the horizontal and vertical simultaneous excitations on the above-mentioned buckling phenomena of support columns experimentally. More-over, they also investigated the fundamental phenomena of the dynamic stability of the support columns subjected to the horizontal and vertical excitations simultaneously by numerical simulations using an analytical model where the support column is treated as a tall elastic cantilever beam. The purpose of this paper is on the dynamic instability, that is dynamic buckling, of a cylindrical shell structures such as those for elevated expressways, towers, containment vessels, LNG tanks and water tanks in various industrial plants so on subjected to horizontal and vertical excitations simultaneously. The coupled motion of equation with horizontal and vertical excitations simultaneously for these cylindrical shell structures is derived in this paper, and this modeling is shown to become a Mathieu type’s parametric excitation. The numerical simulation analysis is carried out for a cylindrical shell model with an attached mass on its tip. Comparing with the classical seismic analysis method, this proposed dynamic instability analysis method shows the larger deformation in horizontal direction due to the parametric excitation of the vertical seismic wave. As the results, the structures are apt to lose the structural stability more due to the coupling effects between the horizontal and vertical seismic simultaneous loadings.
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Deng, J., and X. Q. Wang. "Induced Mechanism of Stope Roof Rockbursts in Underground Excavation." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0214.

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ABSTRACT A rockburst is defined as a sudden and violent disruption of rock in underground excavation. Rockbursts have been regarded as the least understood and the most feared mining disasters. Excavation-induced stress redistribution may lead to slippage of some pre-existing faults or even a new faulting in the near field of an underground opening. Both fault slippage and faulting generate seismic waves that propagate from the hypocenter outward in the rock mass. It was observed that rockbursts are induced by a seismic event when the seismic waves arrive at the free surface of the underground opening. This paper is aimed to study the mechanism of stope roof rockbursts induced by seismic waves using the dynamic buckling theory. The roof is regarded as a beam on elastic foundations under axial seismic waves. The seismic wave is modelled as an excitation with multiple frequencies. A new numerical algorithm is proposed to construct rockburst (instability) diagrams. Our study shows that the amplitude and frequency of the seismic wave play a critical role in the occurrence of roof rockbursts in terms of the mechanisms of perturbation effect and parametric resonance. Based on the mechanism analysis, insights are provided to alleviate the hazard of roof rockbursts. INTRODUCTION In Ontario, Canada, more and more underground mines are operating at depths approximately 3000 meters. With the increase of mining depth, underground mines are generally more prone to ground instability incidents. In underground mines in Ontario, ground instability has been one of the main claims of fatalities. According to statistics, nearly 50 workers were critically injured, and 10 workers died due to rock falls of ground or rockbursts in underground mines in Ontario between 2000 and 2019. A rockburst is defined as a sudden and violent disruption of rock or disturbances of roof or walls in underground excavation, which is caused by or accompanied by a "shock" or tremor (seismic event) of sufficient magnitude, to cause obvious damage to support and excavations, or widespread simultaneous fall of rock. Rockbursts can be classified in terms of the source mechanism and the damage mechanism (Durrheim 1999).
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Trandafir, Aurelian C. "Seismic Coefficients for Simplified Deepwater Slope Stability Assessment Under Earthquake Loading." In Offshore Technology Conference. OTC, 2021. http://dx.doi.org/10.4043/31056-ms.

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Abstract Pseudostatic limit-equilibrium based slope stability analyses are carried out on a routine basis to evaluate stability of submarine slopes under earthquake loading. For slopes in deepwater settings, a major challenge in performing pseudostatic slope stability analyses is selection of an appropriate seismic coefficient. Most published displacement-based methodologies for seismic coefficient selection were developed using simplified sliding block models for seismic slope performance evaluation that are unable to capture the complex deformation mechanism of deepwater slopes during earthquakes. To address this challenge, this study employs two-dimensional dynamic finite-element based deformation analysis to investigate the earthquake response of submarine clay slopes characterized by morphology, stratigraphic architecture and geotechnical properties representative for the deepwater environment. Finite-element computed seismic slope performance indicators, including horizontal peak ground acceleration at the seafloor and earthquake-induced maximum shear strain within the slope, along with horizontal seismic coefficients required to trigger slope instability in limit-equilibrium based pseudostatic stability analyses are used to develop a rational shear strain-based correlation relationship for deepwater slope seismic coefficient selection.
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Huang, Rui, Fengshou Zhang, Mengke An, and Derek Elsworth. "Nucleation of Instability on Granitoid Faults Under Hydrothermal Conditions: Implications for Fluid Injection-Induced Seismicity." In 58th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2024. http://dx.doi.org/10.56952/arma-2024-0039.

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ABSTRACT: Typical in the development of enhanced geothermal systems (EGS), fluid injection for hydraulic stimulation and fracturing hosts the potential for induced seismicity by reactivating deep faults. We use granite cores from the Pohang EGS site in low velocity shear experiments on simulated fault gouges at confining stresses of 110 MPa, temperatures of 100-250 °C and fluid pressures of 21-80 MPa. These experimental conditions are representative of deep geothermal reservoirs and allow the influence of variations in temperature and effective stress to be explored on the nucleation of instability. Our observations document a transition from velocity-strengthening to velocity-weakening response when both the temperature was raised from 100 to 250 °C and the effective confining pressure was reduced from 89 to 30 MPa. Shear deformation localizes in a narrow shear zone with this increased temperature and a transition from fault compaction to dilation evolves with reduced effective stress – congruent with the transition to velocity weakening. These results suggest that high temperature and low effective stress both favor nucleation of earthquake ruptures during fluid injection. Thus, controlling fluid overpressures and being aware of anomalously high thermal gradients potentially enable important controls to be applied in mitigating such injection-induced seismic risks. 1. INTRODUCTION Fluid injection into the deep subsurface is capable of activating nearby faults and triggering seismicity. This phenomenon has been widely reported in numerous underground projects - including for enhanced geothermal systems (EGS), wastewater disposal and shale gas development (Elsworth et al., 2016; Grigoli et al., 2018; Walsh & Zoback, 2015; Bao & Eaton, 2016). For mature faults present in such projects, the frictional properties of the fault typically control fault rupture and seismic response (Ikari et al., 2011; Niemeijer & Collettini, 2014). Thus, detailed characterizations of the evolution of fault strength and stability under hydrothermal conditions are crucial in understanding and mitigating such seismic risk for induced earthquakes.
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Izeiroski, Rustem, and Zlatko Zafirovski. "ANALYSIS OF REASONS FOR INSTABILITY ON CUT-SLOPES AND REMEDIATION MEASURES." In Assessment, maintenance and rehabilitation of structures. Association of Civil Engineers of Serbia, 2024. http://dx.doi.org/10.46793/sgisxiii.19ri.

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Safety of the road is a key factor for undisturbed and fast flow of traffic. Especially, when it comes to motorways which represent the highest rank of road with highest flow of vehicles, the safety in every sense of the word must be satisfied. However, the motorways, aside from the fact that they need to fulfill all the requirements for uninterrupted flow and appropriate speed, they also need to satisfy the safety requirements. One of the safety requirements which must be fulfilled is that the cut slopes must be respectively secured, so there wouldn’t be any problems with rockfalls and landslides. For that reason, a detailed geological features analysis is required, as well as hydrological and seismic conditions of the region. On this paper, a similar example will be analyzed, on the section of the trans-European corridor 8, Kicevo – Ohrid, it will be analyzed one cut slope with its geological features, the problem that were noticed on the field while doing the construction works, stability analysis of the slope, as well as the methods used for remediation and stabilization of the slope.
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Ramini, Abdallah, Mohammad I. Younis, and Quang T. Su. "Low-G Electrostatically Actuated Resonant Switch." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-70328.

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This work investigates a new concept of an electrostatically actuated resonant switch (EARS) for earthquake detection and low-g seismic applications. The resonator is proposed to operate close to instability bands of frequency-response curves, where it is forced to pull-in if operated within these bands. By careful tuning, the resonator can be made to enter the instability zone upon the detection of the earthquake signal, thereby pulling-in as a switch. Such a switching action can be functionalized for alarming purposes or can be used to activate a network of sensors for seismic activity recording. The EARS is modeled and its dynamic response is simulated using a nonlinear single degree of freedom model. Experimental investigation is conducted demonstrating the EARS capability of being triggered at small levels of acceleration as low as 0.02 g. Experimental data and simulation results are compared showing good agreement.
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Reports on the topic "Seismic instability"

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Wang. L52344 Background of Linepipe Specifications. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), December 2011. http://dx.doi.org/10.55274/r0010446.

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Some of the future pipelines are expected to be constructed in remote areas. The environment in these areas can impose higher longitudinal plastic deformation on the pipelines. Such environmental conditions include, but not limited to, frost heave and thaw settlement in the northern arctic region, seismic activity, slope instability, mine subsidence, upheaval buckling, etc. The overall industry experience for this type of loading is very limited. The other trend in new pipeline construction is the move towards higher internal pressure (design factor of 0.80 as opposed to the more traditional 0.72 for Class 1 designs) and the use of high strength linepipes (API 5L Grade X70 and higher). The ability to operate at high international pressure enhances the economic return of the pipelines and provides additional incentive to select high strength line pipe. The focus of this report is the mechanical properties of the linepipes and their influence on pipeline performance. The alloy design of steels, plate and coil rolling practice, and pipe manufacturing process can have profound effects on the resulting mechanical properties of the linepipes. The specifications of these manufacturing parameters leading to the final mechanical properties are out of the scope of this report.
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Yoosef-Ghodsi, Ozkan, and Bandstra. PR-244-114501-R01 Review of Compressive Strain Capacity Assessment Methods Final Report. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), October 2013. http://dx.doi.org/10.55274/r0010402.

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Buried pipelines subjected to non-continuous ground movement such as frost heave, thaw settlement, slope instability and seismic movement experience high compressive strains that can cause local buckling (or wrinkling), in which the pipe wall buckles like a thin cylindrical shell in axial compression. In a strain-based design and assessment framework, excessive local buckling deformation that may cause loss of serviceability, or even pressure containment in some cases, is managed by limiting the strain demand below the strain limit. The determination of compressive strain limit is typically performed by full-scale structural testing or nonlinear finite element analysis that takes into account material and geometric non-linearity associated with the inelastic buckling of cylindrical shells. Before performing testing and numerical analysis (or when such options do not exist), empirical equations are used to estimate the strain limit. In this report a number of representative equations were evaluated by comparing strain limit predictions to full-scale test results. Work prior to this study has identified the importance of key variables that have the greatest impact on the local buckling behaviour. Examples of these variables include the diameter-to-thickness (D/t) ratio, internal pressure and shape of the stress strain curve. The evaluation focused on how existing equations address these key variables, and the performance with respect to key variables and in different ranges.
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