Tesis: "Rock slope failure"

1

De-Vilder, Saskia Joan. "Controls on the evolution of strength and failure style in shallow rock slope failures". Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12819/.

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Rock fall failure comprises fracturing through zones of intact rock, known as rock bridges, and kinematic release along discontinuity surfaces. Understanding controls on magnitude – frequency relationships of rockfalls, and their associated failure characteristics aids susceptibility analysis and interpretation of pre-failure deformation. For failure to occur, these rock bridges must have been weakened, with this damage accumulation driven by a suite of weathering processes. This thesis aims to explore the spatial and temporal controls on weathering induced strength degradation and its subsequent influence on the mechanics of rockfall detachment. Within this, it examines the role of gravitational ambient stress, as dictated by slope topography and rock mass structure, which recent research suggests influences the efficiency of weathering processes. The project integrates field observations, analogue experiments and numerical modelling over varying spatial scales. Terrestrial laser scanning and gigapixel photography are combined to forensically map rock bridge attributes within rockfall detachment surfaces. The role of slope geometry and rock mass structure in concentrating stress is assessed via conceptual finite element models. Finally, samples are subjected to stress conditions induced by the slope structure and environmental conditions in a series of weathering analogue experiments. Together, these results indicate that weathering significantly reduces intact rock strength with areas of stress concentration purely a mechanical control on rockfall release rather than a temporal control on weakening. Weaker rock is characterised by substantial post-peak strength, which requires multiple stages of brittle fracture before ultimate failure occurs. This in turn influences the stages of failure required through rock bridges before final failure, with this number of rock bridges dependent on rockfall size. Mechanically, failure mode is dependent on rock bridge proportion, distribution and location for individual rockfalls. A conceptual model describes magnitude-frequency characteristics and the observable pattern of pre-failure deformation expected for different stages of weathering.

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2

Fadlelmula, Fadlelseed Mohamed Mohieldin. "Probabilistic Modeling Of Failure In Rock Slopes". Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608549/index.pdf.

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This study presents the results of probabilistic modeling of plane and wedge types of slope failures, based on the &rdquo
Advance First Order Second Moment (AFOSM)&rdquo
reliability method. In both of those failure types, two different failure criteria namely, Coulomb linear and Barton Bandis non-linear failure criteria are utilized in the development of the probabilistic models. Due to the iterative nature of the AFOSM method, analyzing spreadsheets have been developed in order to carry out the computations. The developed spreadsheets are called &ldquo
Plane Slope Analyzer (PSA)&rdquo
and &ldquo
Wedge Slope Analyzer (WSA)&rdquo
. The developed probabilistic models and their spreadsheets are verified by investigating the affect of rock and slope parameters such as, ground water level, slope height, cohesion, friction angle, and joint wall compressive strength (JCS) and their distribution types on the reliability index (&
#946
), and probability of slope failure (PF). In this study, different probability distributions are used and the inverse transformation formulas of their non-normal variates to their equivalent normal ones are developed as well. In addition, the wedge failure case is also modeled by using system reliability approach and then the results of conventional probability of failure and the system reliability approach are compared.

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3

CAMONES, LUIS ARNALDO MEJIA. "MODELLING OF STEP-PATH TYPE FAILURE MECHANISMS IN FRACTURED ROCK SLOPE USING DISCRETE ELEMENTS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=33108@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Diferentes mecanismos de ruptura são considerados no momento de avaliar a estabilidade de um maciço rochoso fraturado. Entre estes, os mecanismos de ruptura tipo planar, em cunha e tombamentos têm sido estudados intensivamente, existindo atualmente modelos matemáticos que permitem avaliá-los. Estes mecanismos de ruptura são restritos a taludes pequenos e com fraturas contínuas, nas quais o deslizamento ocorre ao longo destas descontinuidades. Em casos de taludes de grande altura ou quando a persistência das fraturas é pequena em relação à escala do talude, o fraturamento torna-se descontínuo. Neste caso, o mecanismo de ruptura mais provável é o tipo Step-Path, o qual, a superfície de ruptura é formada por fraturas que se propagam através da rocha intacta juntando-se entre elas. Este fenômeno de união de fraturas é chamado de coalescência. Análises de estabilidade, como os probabilísticos ou por equilíbrio limite, são usados atualmente para avaliar estes tipos de rupturas, não se tendo ainda o desenvolvimento de um modelo numérico que possa representá-lo e reforçar estas teorias. O presente trabalho avalia o uso do Método dos Elementos Discretos na modelagem do mecanismo de ruptura tipo step- path, realizando uma análise de estabilidade que permita comparar os seus resultados com o método de equilíbrio limite. Foi utilizado o programa PFC nas versões 2D e 3D, assim como o programa FracGen para a geração de fraturas tridimensionais. A análise tridimensional foi feita mediante um acoplamento PFC3D-FracGen. A pesquisa inclui a análise e modelagem dos fenômenos de coalescência em amostras, assim como a influência da anisotropia na resistência das rochas em ensaios triaxiais.
Different failure mechanisms are considered when a fracturated rock mass is valued. Some of them are being subject of accurate study, like planar failure mechanism, wedges and toppling, which are currently valued by mathematical models. These failure mechanisms are restricted to small slopes and with continue fractures, where the sliding occurs along these discontinuities. To height slopes or when the fracture persistence is smaller than the slope scale, the fracturing becomes discontinuous. In this case, the most probable failure mechanism to happen is the step-path type, in which the failure surface is composed by fractures that propagate through the intact rock and that are joined together. This phenomenon of fracture union is known as coalescence. Stability analysis, like probability analysis or limit equilibrium analysis are currently utilized to evaluate this kind of failures, but its important to develop a numerical model to represent and reinforce these theories. This work aims to evaluate the use of Discrete Element Method to model step-path failure mechanism on a stability analysis and to compare the results with limit equilibrium method. The program used to simulate the slope is PFC (2D and 3D) and the program FracGen was used to generate three-dimensional fractures. Three-dimensional analysis was done by a coupling between PFC3D and FracGen. The research includes the analysis and modeling of coalescence phenomenon on rock samples, as well as the analysis of the anisotropy influence on rock strength obtained from triaxial tests.

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4

Chiaravalloti, Rosario. "Numerical modelling and back analysis of a rock slope failure occurred in 2005 at Scascoli (Bologna, Italy)". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.

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The rock slope failure object of this study occurred on the 12th of March, 2005, within the Scascoli Gorges in the Savena Valley, 25 km south of Bologna, in the Northern Apennines, Italy. The failure involved a volume of rock of nearly 30000 m3 that detached from an 80 m high cliff and fell on the river bed and onto the adjacent road, denoted as “Strada Provinciale – Fondovalle Savena”, damming the first and destroying the latter. The conformation of the cliff, known as “Mammellone 1”, was rather convex, overhanging and undercut at the base where in contact with the river bed. The event is the last of a series of mass movements which occurred in a 15-year span in the area. With integration of past analyses and surveys, possible causes and mechanism of failure have been investigated by means of two and three-dimensional kinematic analysis (using the software DIPS and SWEDGE by Rocscience, 2016), photogrammetry and terrestrial laser scanning comparison (Cloud Compare, Daniel Girardeau-Montaut, 2016; Autocad, Autodesk, 2016) and two-dimensional finite element numerical modelling (RS2, Rocscience, 2016). The use of a finite element method to model a predominantly blocky structure has shown to be effective and to produce good results if data integration, boundary conditions and geometry of the site are well correlated between each other to best fit the resulting scenario. The design of the numerical model considered the relative position of crown and scarp to the discontinuity families and to the geometry of the cross section, to better costrain the failure surface. Furthermore, the process of formation of the valley was taken into account in order to consider also stress-strain conditions prior to the road construction and river erosion. This was carried out by multi-staging the modelling process considering the natural erosion and the advancement of the landslide on the hydrogeological left side of the Savena steam before the last rockfall event.

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5

PIOVANO, GIOVANNA. "Combined finite-discrete element modelling of key instabilities which characterise deep-seated landslides from massive rock slope failure". Doctoral thesis, Politecnico di Torino, 2012. http://hdl.handle.net/11583/2502740.

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The expression “landslide from massive rock slope failure” (MRSF) is used to indicate large-scale landslides characterised by a variety of complex initial failure processes and unpredictable postfailure behaviour. In this context, deep-seated landslides are classified as “landslides from massive rock slope failure”. Typically, deep-seated landslides are slow mountain deformations which may involve movement along discrete shear surfaces and deep seated mass creep. The long-term development of deep-seated slope deformations creates suitable conditions for the subsequent occurrence of other slope deformations. Deep-seated landslides in mountain areas can be spatially interconnected with other types of slope deformations such as debris flows, debris slides, rock avalanches, topple, translational, rotational and compound sliding and complex type of mass movements. It is to be recognized that many aspects of large-scale landslides need be investigated in order to gain the necessary confidence in the understanding and prediction of their behaviour and in the associated risk assessment. The present thesis is to contribute to such understanding with specific reference to a number of mass movements which characterize large-scale landslides. An advanced numerical technique (FDEM) which combines finite elements with discrete elements has been applied in this thesis for improving such understanding. The open source research code, called Y2D, developed at the Queen Mary, University of London by Prof. Munjiza has been used. Considering that this code has not yet been applied to slope stability problems, a series of numerical tests have been carried out to assess its suitability to properly and efficiently simulate geomechanical problems. To this purpose standard rock failure mechanisms as well as laboratory tests have been modelled first and the results obtained have been compared with available analytical and numerical solutions. The advantages of the application of FDEM has been outlined by showing that both the simulation of failure initiation and progressive development to fragmentation of the rock mass is possible as this is deposited at the slope toe. The case study of interest for this thesis is the Beauregard massive landslide located in the Aosta Valley (Northwestern Italy). At this site the presence of an extensive deep-landslide insisting on the left abutment of an arch-gravity dam is well recognised. Based on detailed studies, the investigated area has been subdivided into zones which are characterised by different geomorphologic and geostructural features. Different landslide mechanics as well as different landslide activities upstream of the dam site have been identified and studied in detail. Such an area is thought to be at an intermediate stage of development of the deep seated landslide compared with the sector which insists on the dam. The observed failure mechanism has been ascribed to a large sliding on a compound surface. Some other failure mechanisms have been recognized, such as large flexural toppling and local block toppling instability. The final part of the thesis has been devoted to the FDEM numerical modelling of a large scale failure mechanism based on brittle behaviour of the rock mass. The aim is to apply the “total slope failure” approach through the application of FDEM. Such a technique has demonstrated the significant potential in predicting the development of possible slope instability phenomena.

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6

Büch, Florian. "Seismic response of Little Red Hill - towards an understanding of topographic effects on ground motion and rock slope failure". Thesis, University of Canterbury. Geological Sciences, 2008. http://hdl.handle.net/10092/1251.

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A field experiment was conducted at near Lake Coleridge in the Southern Alps of New Zealand, focusing on the kinematic response of bedrock-dominated mountain edifices to seismic shaking. The role of topographic amplification of seismic waves causing degradation and possible failure of rock masses was examined. To study site effects of topography on seismic ground motion in a field situation, a small, elongated, and bedrock-dominated mountain ridge (Little Red Hill) was chosen and equipped with a seismic array. In total seven EARSS instruments (Mark L-4-3D seismometers) were installed on the crest, the flank and the base of the 210 m high, 500 m wide, and 800 m long mountain edifice from February to July 2006. Seismic records of local and regional earthquakes, as well as seismic signals generated by an explosive source nearby, were recorded and are used to provide information on the modes of vibration as well as amplification and deamplification effects on different parts of the edifice. The ground motion records were analyzed using three different methods:comparisons of peak ground accelerations (PGA), power spectral density analysis (PSD), and standard spectral ratio analysis (SSR). Time and frequency domain analyses show that site amplification is concentrated along the elongated crest of the edifice where amplifications of up to 1100 % were measured relative to the motion at the flat base. Theoretical calculations and frequency analyses of field data indicate a maximum response along the ridge crest of Little Red Hill for frequencies of about 5 Hz, which correlate to wavelengths approximately equal to the half-width or height of the edifice (~240 m). The consequence of amplification effects on the stability and degradation of rock masses can be seen: areas showing high amplification effects overlap with the spatial distribution of seismogenic block fields at Little Red Hill. Additionally, a laboratory-scale (1:1,000) physical model was constructed to investigate the effect of topographic amplification of ground motion across a mountain edifice by simulating the situation of the Little Red Hill field experiment in a smallscale laboratory environment. The laboratory results show the maximum response of the model correlates to the fundamental mode of vibration of Little Red Hill at approximately 2.2 Hz. It is concluded that topography, geometry and distance to the seismic source, play a key role causing amplification effects of seismic ground motion and degradation of rock mass across bedrock-dominated mountain edifices.

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7

Bonilla, Sierra Viviana. "De la photogrammétrie à la modélisation 3D : évaluation quantitative du risque d'éboulement rocheux". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI072/document.

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Les analyses structurale et mécanique des pentes rocheuses constituent des éléments clés pour l'évaluation de leur stabilité. L'utilisation complémentaire de la photogrammétrie et des modèles numériques qui couplent les réseaux discrets de discontinuités (DFN selon son sigle en anglais) avec la méthode des éléments discrets (DEM selon son sigle en anglais), présente une méthodologie qui peut être utilisée pour évaluer le comportement mécanique des configurations tridimensionnelles de terrain pour lesquelles l'existence de discontinuités non persistantes peut être supposée. La stabilité des masses rocheuses est généralement supposée être contrôlée par la résistance au cisaillement le long des plans de discontinuité. Si les discontinuités sont non persistantes, avec leur continuité interrompue par la présence de ponts rocheux (portions de roche intacte reliant la masse rocheuse au massif), leur résistance apparente augmente considérablement. Dans ce cas, la contribution des ponts rocheux localisés entre ces discontinuités doit être prise en compte dans l'analyse de stabilité. La déstabilisation progressive des massifs rocheux dans lesquels des discontinuités non persistantes sont présentes, peut être étudiée par des simulations numériques réalisées à l'aide de l'approche DEM. La roche intacte est représentée comme un assemblage de particules (ou éléments discrets) liées entre elles par des contacts dont les lois de comportement spécifiques peuvent être calibrées pour représenter correctement le comportement de la roche. L'intérêt de la méthode est qu'elle permet de simuler l'initiation de la rupture et sa propagation à l'intérieur de la matrice rocheuse du fait de la rupture des contacts cohésifs entre les particules. De plus, les discontinuités préexistantes peuvent être prises en compte explicitement dans le modèle en utilisant une loi de contact ad hoc qui assure un comportement mécanique représentatif des plans de discontinuité. Des analyses de stabilité ont été effectuées et ont mis en évidence le rôle des ponts rocheux dans la génération de nouvelles surfaces de rupture qui peuvent se développer à travers des mécanismes de rupture mixte en traction et en cisaillement. On peut considérer la formulation de Jennings comme l'une des premières méthodes d'analyse de la stabilité des pentes rocheuses qui évaluent la résistance au glissement comme une combinaison pondérée des résistances mécaniques des ponts rocheux et des plans de discontinuité. Sa validité a été discutée et systématiquement comparée aux résultats obtenus à partir de simulations numériques. Il a pu être montré que la formulation de Jennings perd sa validité dès que la rupture des ponts rocheux intervient majoritairement par des mécanismes de traction. Une formulation complémentaire a alors été proposée. En ce qui concerne l'étude de la stabilité des massifs rocheux sur site, il a été montré que l'association entre les données issues de la photogrammétrie en haute résolution et l'approche DFN-DEM peut être utilisée pour identifier des scénarios de rupture. L'analyse en retour de cas réels a montré que les surfaces de rupture peuvent être simulées comme le résultat de mécanismes combinant la fracturation des ponts rocheux et le glissement le long des discontinuités préexistantes. La rupture d'un dièdre qui a eu lieu dans une mine de charbon australienne, a été utilisée pour valider cette méthodologie. Des simulations numériques ont été réalisées pour déterminer les scénarios pour lesquels les surfaces de rupture simulées et celles repérées sur le terrain, peuvent être utilisés pour calibrer les paramètres de résistance du modèle numérique. Le travail présenté ici répond à un besoin plus général visant à améliorer la gestion des risques naturels et miniers liés aux masses rocheuses instables. La méthodologie proposée constitue une alternative robuste dédiée à renforcer la fiabilité des analyses de stabilité pour les pentes rocheuses fracturées à structure complexe
Structural and mechanical analyses of rock mass are key components for rock slope stability assessment. The complementary use of photogrammetric techniques and numerical models coupling discrete fracture networks (DFN) with the discrete element method (DEM) provides a methodology that can be applied to assess the mechanical behaviour of realistic three-dimensional (3D) configurations for which fracture persistence cannot be assumed. The stability of the rock mass is generally assumed to be controlled by the shear strength along discontinuity planes present within the slope. If the discontinuities are non–persistent with their continuity being interrupted by the presence of intact rock bridges, their apparent strength increases considerably. In this case, the contribution of the rock bridges located in-between these discontinuities have to be accounted for in the stability analysis. The progressive failure of rock slope involving non–persistent discontinuities can be numerically investigated based upon simulations performed using a DEM approach. The intact material is represented as an assembly of bonded particles interacting through dedicated contact laws that can be calibrated to properly represent the behaviour of the rock material. The advantage of the method is that it enables to simulate fracture initiation and propagation inside the rock matrix as a result of inter-particle bond breakage. In addition, pre–existing discontinuities can be explicitly included in the model by using a modified contact logic that ensures an explicit and constitutive mechanical behaviour of the discontinuity planes. Stability analyses were carried out with emphasis on the contribution of rock bridges failure through a mixed shear-tensile failure process, leading to the generation of new failure surfaces. Jennings' formulation being considered to be one of the first rock slope stability analysis that evaluates the resistance to sliding as a weighted combination of both, intact rock bridges and discontinuity planes strengths, its validity was discussed and systematically compared to results obtained from numerical simulations. We demonstrate that the validity of Jennings' formulation is limited as soon as tensile failure becomes predominant and an alternative formulation is proposed to assess the resulting equivalent strength. Regarding field slope stability, we show that the combination of high resolution photogrammetric data and DFN-DEM modelling can be used to identify valid model scenarios of unstable wedges and blocks daylighting at the surface of both natural and engineered rock slopes. Back analysis of a real case study confirmed that failure surfaces can be simulated as a result of both fracture propagation across rock bridges and sliding along pre-existing discontinuities. An identified wedge failure that occurred in an Australian coal mine was used to validate the methodology. Numerical simulations were undertaken to determine in what scenarios the measured and predicted failure surfaces can be used to calibrate strength parameters in the model. The work presented here is part of a more global need to improve natural and mining hazards management related to unstable rock masses. We believe that the proposed methodology can strengthen the basis for a more comprehensive stability analysis of complex fractured rock slopes

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8

Jarvis, Jeremy James. "Large scale toppling failure in metamorphic rock slopes". Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/11287.

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9

Ковров, Олександр Станіславович, Александр Станиславович Ковров y O. S. Kovrov. "Геомеханічне обґрунтування параметрів стійких укосів кар’єрів в складноструктурному масиві м’яких порід". Thesis, Видавництво НГУ, 2011. http://ir.nmu.org.ua/handle/123456789/152.

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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.15.09 – «Геотехнічна і гірнича механіка». – ДВНЗ «Національний гірничий університет», Дніпропетровськ, 2011.
Диссертация на соискание ученой степени кандидата технических наук по специальности 05.15.09 – «Геотехническая и горная механика». – ГВУЗ «Национальный горный университет», Днепропетровск, 2011.
Thesis for obtaining scientific degree of Candidate of Technical Sciences in specialty 05.15.09 - Geotechnical and rock mechanics. – State Higher Educational Institution “National Mining University”, Dnipropetrovs’k, 2011.
Дисертація присвячена вирішенню актуальної науково-технічної задачі вдосконалення геомеханічної оцінки стійкості укосів уступів на кар’єрах, що складаються з м’яких розкривних порід, з урахуванням складної геологічної структури, гідрогеологічних характеристик родовища й навантажень від гірничо-транспортного устаткування. У роботі виконаний аналіз впливу фізико-географічних, природно-геологічних, гідрогеологічних, інженерно-геологічних і гірничо-технічних факторів на геомеханічну стійкість укосів і бортів кар’єрів. Результати моделювання на еквівалентних матеріалах та чисельного моделювання методом кінцевих елементів дозволило проаналізувати геомеханічні процеси у породних уступах і встановити закономірності порушення їх стійкості. Отримані експериментальним шляхом фізико-механічні характеристики розкривних порід (суглинки, глини) для гірничо-геологічних умов кар’єрів №7 "Північ" й №7 "Південь" Вільногірського ГМК використані для геомеханічної оцінки стійкості укосів уступів залежно від фізико-механічних характеристик, вологості порід і навантажень від гірничо-транспортного устаткування. Закономірності, отримані в результаті експериментальних досліджень зразків гірських порід і чисельного моделювання використані для розробки рекомендацій із забезпечення геомеханічної стійкості укосів розкривних уступів для гірничо-геологічних та гірничотехнічних умов Мотронівсько-Анновської ділянки Малишевського комплексного циркон-рутил-ільменітового родовища, що планується до введення в експлуатацію на ВГМК.
Диссертация посвящена усовершенствованию геомеханической оценки устойчивости откосов уступов на карьерах, сложенных мягкими вскрышными породами, с учетом сложной геологической структуры, гидрогеологических характеристик месторождения и нагрузок от горно-транспортного оборудования. В работе выполнен анализ влияния физико-географических, природно-геологических, гидрогеологических, инженерно-геологических и горно-технических факторов на геомеханическую устойчивость откосов и бортов карьеров; рассмотрены основные подходы к расчету потенциальных поверхностей скольжения в прибортовом массиве пород, а также аналитические и эмпирические критерии прочности, которые наиболее часто используются в практике геомеханических исследований. Для моделирования устойчивости откосов и бортов карьеров, сложенных мягкими вскрышными породами, принят критерий прочности Кулона-Мора. В качестве инструмента численного моделирования использована программа конечно-элементного анализа Phase2 компании Rocscience Inc. широко используемая в практике инженерного анализа как в Украине, так и за рубежом. Использование метода моделирования на эквивалентных материалах позволило проанализировать геомеханические процессы, происходящие при сдвижении массива пород, слагающих породный уступ, и установить закономерности нарушения его устойчивости. Выполнены серийные испытания образцов на одноплоскостном срезном приборе П10-С и определены физико-механические характеристики вскрышных пород (суглинки, глины) для горно-геологических условий карьеров №7 «Север» и №7 «Юг» Вольногорского ГМК. Полученные экспериментальным путем значения сцепления и угла внутреннего трения использованы для геомеханической оценки устойчивости откосов уступов действующих и проектируемых карьеров ВГМК. Разработана гидрогеомеханическая модель, описывающая распределение деформаций и напряжений в откосах уступов карьера с учетом физико-механических характеристик верхнего слоя вскрыши и влагонасыщения пород за счет инфильтрации атмосферных осадков. По результатам моделирования определены коэффициенты запаса устойчивости борта карьера в зависимости от физико-механических характеристик, влажности вмещающих пород и внешних нагрузок горно-транспортного оборудования. Закономерности, полученные в результате экспериментальных исследований образцов горных пород и численного моделирования использованы для разработки рекомендаций по обеспечению геомеханической устойчивости откосов вскрышных уступов для горно-геологических и горнотехнических условий Мотроновско-Анновского участка Малышевского комплексного циркон-рутил-ильменитового месторождения, которое планируется к введению в эксплуатацию на ВГМК. Разработан алгоритм оценки долговременной геомеханической устойчивости откосов и бортов карьеров, учитывающий геометрические параметры уступов, сложную геологическую структуру породного массива, гидрогеологические характеристики месторождения и нагрузки от горно-транспортного оборудования. Рассчитаны зависимости угла откоса уступа от влажности верхнего вскрышного горизонта суглинков. Установлено, что для существующих гидро-геологических условий с учетом физико-механических свойств пород рекомендуемые значения КЗУ=1,1…1,3 будут обеспечены при угле наклона откоса α=37…47°. В результате комплексной оценки геомеханической устойчивости откосов разработана номограмма для расчета КЗУ и рациональных геометрических параметров вскрышных уступов, сложенных суглинками. Установлено, что при средней высоте вскрышного уступа 20 м и изменении угла наклона откоса с проектных 37º до рекомендуемых 47º для условий Вольногорского горно-металлургического комбината сокращение объемов вскрышных работ на 1 км длины фронта работ составит ∆V=78,91тыс.м3. В результате корректировки угла наклона откоса и формировании более крутого геометрического профиля уступа, при его высоте Н=20 м, на 10° (α1-α2=47°-37°) рассчитан экономический эффект Сэ=0,72…0,90 млн. грн на 1 км длины фронта горных работ при средней себестоимости вскрыши Св=10,85…13,40 грн/м3.
The dissertation is devoted to solving an actual scientific and technical task of improving geomechanical evaluation of slope stability in open-pit benches composed of soft rocks with consideration of complex geological structure, deposit hydro-geological characteristics and loads of mining-transportation equipment. Analysis of influence of physiographic, geological, hydro-geological, geotechnical and mining-technical factors on geomechanical stability of slopes and pitedges is carried out. Results of simulation of equivalent materials and FEM numerical modeling allowed analyze geomechanical processes in rock benches and ascertain laws of their instability. Experimentally derived physical and mechanical characteristics of overburden rocks (loams, clays) for geological conditions of open-pits №7 "Sever" and №7 "Yug" of Vil’noghirs’k Mining and Metallurgical Plant (VGMK) are used for geomechanical evaluation of slope stability depending on physical and mechanical characteristics, rock moisture, and external loads from mining and transport equipment. Regularities obtained in experimental research of rock samples and numerical modeling are used to develop recommendations for ensuring geomechanical slope stability of overburden benches for geological and mining conditions of Motronivs’ko-Annovs’kyi section of Malyshevs’ke complex zircon-rutile-ilmenite placer deposit which is planned to put into exploitation on VGMK.

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10

Anyintuo, Thomas Becket. "Seepage-Coupled Finite Element Analysis of Stress Driven Rock Slope Failures for BothNatural and Induced Failures". Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7731.

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Rock slope failures leading to rock falls and rock slides are caused by a multitude of factors, including seismic activity, weathering, frost wedging, groundwater and thermal stressing. Although these causes are generally attributed as separate causes, some of them will often act together to cause rock slope failures. In this work, two of the above factors, seepage of water through cracks and crack propagation due to the after effects of blasting are considered. Their combined impact on the development of rock falls and rock slides is modeled on ANSYS workbench using the Bingham Canyon mine slope failure of 2013 as a case study. Crack path modeling and slope stability analysis are used to show how a combination of crack propagation and seepage of water can lead to weakening of rock slopes and ultimate failure. Based on the work presented here, a simple approach for modeling the development of rock falls and rock slides due to crack propagation and seepage forces is proposed. It is shown how the information from remote sensing images can be used to develop crack propagation paths. The complete scope of this method involves demonstrating the combination of basic remote sensing techniques combined with numerical modeling on ANSYS workbench.

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11

Kou, Yan. "Wedge failure analysis of anchored rock slopes subjected to surcharge and seismic loads". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2015. https://ro.ecu.edu.au/theses/1736.

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Slope stability in mining and civil engineering projects is always a problem of great concern. Because the rock mass behavior is significantly governed by the presence of joints or other discontinuities, several types of slope failure, such as plane failure, wedge failure, toppling failure, buckling failure and circular failure, are often observed. The present work focuses on the study of the wedge failure, which occurs as sliding of a mass of rock on two intersecting planes, generally discontinuity planes. Recently, the factor of safety of rock slopes against the wedge failure has been studied in a number of investigations under static and/or dynamic conditions by different methods such as the limit equilibrium method, numerical modeling method, reliability method and stereographic method. However, the anchored rock slope against the wedge failure subjected to surcharge and seismic load has not yet been studied in detail in earlier studies. In this thesis, the rock slope subjected to the generalized loads such as surcharge and seismic/dynamic loads is analyzed against the wedge failure by the limit equilibrium method. The expression for the factor of safety was derived for the cases with anchors and without anchors separately. In addition, a parametric study is carried out to demonstrate the effects of the most relevant governing parameters on the stability of rock slope. The parameters include geometrical parameters, joint material properties, unit weight of rock, anchor inclination and hydraulic parameters. Several special cases of the developed generalized expression result in the expressions for the factor of safety for simplified field situations as reported in the literature. The parametric study shows that most parameters as mentioned above affect the factor of safety ( FS ) of the rock slope against the wedge failure significantly. In order to find an easy way to work on the parametric analysis, the “ * ” indicates dimensionless parameters. It is observed that the surcharge would always be a destabilizing force when the cohesion (c* ) is not zero; the FS decreases with an increase in surcharge. However, when c* = 0, the FS increases slightly with an increase in surcharge. The anchor forces (T* ) would always be a stabilizing force that makes the FS increase with an increase in T*. As the angle of inclination of the joint plane/failure plane to the horizontal ( p y ) increases, the FS increases nonlinearly; it increase sharply by 60% from 42° to 45° while it deceases nonlinearly by 67% with an increase in the slope angle (yf ) from 40° to 60°. It is also observed that the FS decreases with an increase in horizontal seismic acceleration coefficient (k h ) and the vertical seismic acceleration coefficient (k v ), separately, while it increases linearly with an increase in the following parameters: the cohesion (c* ) and the angle of shearing resistance ( f ), separately. The FS increases with an increase in inclination of stabilizing force to the normal at the failure plane (a ); it becomes maximum when a increases to 80°. However, the unit weight of rock (g* ) does not affect the FS significantly.

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Kimber, Owen Graham. "Mechanisms of failure of jointed rock masses and the behaviour of steep slopes". Thesis, Durham University, 1998. http://etheses.dur.ac.uk/4910/.

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The geomorphological behaviour of steep jointed rock slopes has been studied using distinct element method computer models. In order to model steep slopes effectively, methodologies need to be combined from the studies of environmental modellers, geomorphologists and engineers. The distinct element method is ideal for the study of the development of jointed rock masses as the discontinuum approach can model the progressive failure of rock blocks along discontinuities. Initial, theoretical modelling identified the limiting boundary conditions between the multiple block failure mechanisms of toppling, sliding and toppling-and-sliding, based upon the discontinuity geometry for a theoretically modelled limestone rock mass. It is demonstrated that joint dip, friction angle and spacing exert the greatest control upon rock mass failure mechanisms. Two field locations, the Colorado Plateau and the Isle of Purbeck, have been chosen to provide a link between theoretical modelling and classic rock mass landforms which are controlled by variation in discontinuity geometry. In the Portland Limestone of the Isle of Purbeck, it is the joint geometry variation which influences development. Bedding steepens and average block size decreases in the coastal rock cliffs from east to west. Comparison between the model outputs highlighted that there is an increase in the rate of simulated cliff retreat from Winspit in the east to Durdle Door in the west. The Colorado Plateau rock cliffs form large, embayed plan-form escarpments and detached monoliths. It is the variation of joint set spacing in the cap-rock of cuesta-form composite scarps that controls development. Model results suggest there is a continuum of rock mass landforms, with buttes becoming detached at plan-form necks in the escarpment as determined by the joint geometry. The results show excellent similarity with the landforms observed in the field. This thesis introduces a research tool that can provide an understanding of slope behaviour.

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13

Southall, David Wray. "Characteristics and age of rock-slope failures on the western edge of the Antrim plateau". Thesis, Ulster University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.674737.

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RSFs on the western edge of the Antrim Plateau of the North Atlantic Igneous Province are mapped in detail from a 5m resolution Digital Elevation Model and aerial photos. The maps, digitally produced in ArcMap 9.2, aerial photos and field observations have been combined to describe landform morphology. The digital maps have been used innovatively to obtain the morphometric data of selected landforms representative of the variety of deep-seated and superficial failures that occur and hence to classify them by both their morphology and process of movement. The experimental use of Ground Penetrating Radar, pioneered on rock-slope failure debris in a wet environment, determined the near-surface structure of failure debris and investigated some areas of incipient failures at cliff tops. The age of the failures is assessed from Cosmogenic Nuclide (36CI) Exposure Dating, Radiocarbon Dating and Schmidt Hammer Rebound testing. Long-term deep-seated rotational and translational failures due either paraglacial conditioning or marine erosion or both occurred in oscillating climate phases that spanned the Woodgrange Stadial of the Late Glacial period to the middle of the Littletonian warm period (c. 14.7-5 ka BP). Superficial failures due to periglacial freeze-thaw action on cliff faces occurred in the Nahanagan Stadial, in Littletonian climate reversals (9.3 and 8.2 ka BP), during the Little Ice Age and in cold periods that still exist to the present day.

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14

Cathala, Maëva. "Cartographier et modéliser les aléas liés à la dégradation de la cryosphère dans les Alpes Françaises : Une approche multiscalaire combinant permafrost, lacs glaciaires et écroulements rocheux pour contribuer à l'identification de secteurs à risque". Electronic Thesis or Diss., Chambéry, 2024. http://www.theses.fr/2024CHAMA003.

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Dans les Alpes françaises, la dégradation de la cryosphère se traduit en partie par le recul généralisé des glaciers et la dégradation du permafrost. Le retrait glaciaire peut conduire à la formation de nouveaux lacs, tandis que la dégradation du permafrost peut déstabiliser les parois rocheuses qui les surplombent. Dans ce contexte, des écroulements ou avalanches rocheuses peuvent générer des aléas en cascade, se propageant jusqu'au fond des vallées. L'anticipation de ces évènements aux effets parfois dévastateurs, constitue un véritable enjeu pour les acteurs et les populations des milieux montagnards. Face à ces défis sociétaux, les objectifs de ce travail doctoral sont (i) d'identifier les secteurs à risque en termes d'écroulements et d'avalanches rocheuses et des aléas en cascade qu'ils peuvent entrainer, et (ii) d'approfondir la connaissance fondamentale sur les processus physiques qui prédisposent, déclenchent, et propagent les écroulements ou avalanches rocheuses en contexte de permafrost.Nous proposons une approche intégrée qui fait le lien entre des observations de terrain, des mesures in-situ, de la modélisation numérique et de la cartographie des écroulements et avalanches rocheuses en contexte de permafrost dans les Alpes françaises. Nous suivons une logique multi-scalaire spatio-temporelle, allant de l'échelle régionale (Alpes françaises), à l'échelle locale (versant) ; en considérant les conditions environnementales passées, actuelles, et futures (horizon de la fin du 21ème siècle).A l'échelle régionale, la cartographie des zones de départ montre que les secteurs instables pourraient s'étendre entre 34 km² (scénario considérant uniquement les parois les plus instables) et 284 km² (scénario le plus conservateur) dans les conditions actuelles de permafrost, tandis que les zones de propagation pourraient atteindre entre 472 km² à 586 km² selon le scénario de propagation choisi. Selon le scénario de propagation, entre 53 et 90 lacs pourraient être atteints par des potentiels écroulements rocheux. En considérant un réchauffement +4°C des parois d'ici la fin du 21ème siècle, les zones de départ s'étendraient sur 43,2 km², tandis que les zones de propagation pourraient atteindre entre 196 km² et 245 km² selon le scénario de propagation. Ainsi, dans les conditions futures de la cryosphère, 27 à 51 lacs pourraient se trouver dans la trajectoire d'un écroulement rocheux.A l'échelle du site, notre approche combine des méthodes à différentes échelles spatio-temporelles afin de mieux comprendre les processus thermiques et hydrologiques impliqués dans les mécanismes de déclenchement et de propagation d'écroulements rocheux et d'avalanches rocheuses. La rétro-analyses de deux cas d'étude situés dans le vallon d'Etache (Savoie) et à la crête des Grangettes (Hautes Alpes) a révélé un réchauffement du permafrost depuis les années 1990 qui s'est accentué depuis les années 2010 (e.g. jusqu'à + 0.06 °C/an à 30 m de profondeur au vallon d'Étache). Dans le cas du vallon d'Étache, la déstabilisation du versant peut être attribuée à une transition entre un permafrost froid vers un permafrost tempéré, et à des infiltrations d'eau qui ont pu entraîner une augmentation de la pression hydrostatique et/ou participer à l'érosion de la glace dans les fractures. Les investigations menées à la Crête des Grangettes ont quant à elles montré un réchauffement du permafrost vers le point de fusion qui a pu entrainer une rupture des joints de glace. Ces études soulignent enfin la difficulté d'évaluer le rôle de la neige et de l'eau dans les mécanismes qui prédisposent, déclenchent et propagent mouvements de versants.Les résultats obtenus ont pour but de fournir, à terme, des informations précieuses pour la communauté scientifique et les acteurs du territoire, afin d'approfondir la compréhension des aléas liés à la dégradation de la cryosphère et de contribuer à mettre en œuvre des solutions concrètes pour aider les populations à y faire face
In the French Alps, the degradation of the cryosphere partly results in glacier retreat and permafrost degradation. Glacier retreat can lead to the formation of new lakes, while permafrost degradation can cause rockwalls destabilisations. In this context, rockfalls and rock avalanches can generate cascading hazards, spreading down to the valley floors. Anticipating these events and their devastating effects, is a challenge for stakeholders and populations living in mountainous regions. In this context, the objectives of this work are (i) to identify the areas at risk to be impacted by rockfalls, rock avalanches and their potential cascading hazards, and (ii) to deepen fundamental knowledge on the processes predisposing, triggering, and propagating rockfalls or rock avalanches from permafrost rockwalls.We propose an integrated approach that links field observations, in-situ measurements, numerical modelling, and regional mapping of rockfalls and rock avalanches in permafrost contexts in the French Alps. To do so, we follow a multi-scale spatio-temporal approach, ranging from the regional scale (French Alps) to the local scale (slope), and considering past, current, and future cryospheric conditions (by the end of 21st century).At the regional scale, release areas maps show that unstable slopes could extend between 34 km² (scenario considering only the most unstable slopes) and 284 km² (most conservative scenario) under current permafrost conditions. Propagation maps shows that rockfalls (>100 m3) could reach between 472 km² to 586 km² depending on the chosen propagation scenario. Thus, between 53 and 90 lakes could potentially be impacted by rockfalls. Considering a +4°C warming of the rockwalls by the end of the 21st century, release areas would extend to 43.2 km², while propagation zones could reach between 196 km² and 245 km² depending on the propagation scenario. Thus, under future cryospheric conditions, 27 to 51 lakes could be in a rockfall path.At the site scale, we used an approach combining methods at different spatio-temporal scales to understand the thermal and hydrological processes involved in the triggering and propagation mechanisms of rock slope failures. The retro-analyses of two study cases located in the Étache valley (Savoie) and at the Grangettes ridge (Hautes Alpes) shows a warming of the permafrost since the 1990s, which has significantly intensified since the 2010s (e.g. up to +0.06°C/year at 30 m depth in the Étache valley). In the case of the Étache valley, the rock avalanche occurs in a context of transition from cold to temperate permafrost, and with water infiltration that may have led to high hydrostatic pressure and ice erosion in fractures. Investigations conducted at the Grangettes ridge show a warming of permafrost towards the melting point, which may have caused ice joint ruptures. These studies also highlight the difficulty of assessing the role of snow and water in the predisposing, triggering, and propagating mechanisms of slope instabilities.The results offer valuable insights for both the scientific community and stakeholders, facilitating a deeper understanding of the hazards associated with cryosphere degradation and contributing to the development of concrete solutions to support populations in addressing these challenges

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15

Hossain, Md M. "Stability analysis of anchored rock slopes against plane failure subjected to surcharge and seismic loads". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2011. https://ro.ecu.edu.au/theses/139.

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The stability analysis of rock slopes has been a challenging task for engineers because the rock mass constituting the slope often has discontinuities in various forms, resulting in different types of slope failures. The plane failure is one of the rock slope failures observed in field situations when the discontinuity is in the form of joint planes. There are several parameters including surcharge and seismic loads that govern the stability of the rock slope against plane failure in field projects. The limit equilibrium approach for the estimation of the factor of safety of the rock slope against plane failure has been well accepted by the engineers in the past. Very recently, attempts have been made to present analytical expressions for the factor of safety of the of the rock slopes against plane failure, which are not in a generalised form because they do incorporate most field parameters. Therefore, in the present work, the analytical expression for the factor of safety of a single-directional anchored rock slope (SDARS) is derived, along with a discussion of its special cases in view of different practical situations. Parametric studies and design charts for the stability of the SDARS are presented, and an illustrative example is included to explain the calculation steps for the factor of safety. In order to investigate the effect of multi-directional rock anchors on the factor of safety, an analytical expression for a multi-directional anchored rock slope (MDARS) is also presented.

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16

Schleier, Markus T. [Verfasser], Joachim [Akademischer Betreuer] Rohn y Reginald L. [Akademischer Betreuer] Hermanns. "Rock-slope failures in Innerdalen and Innfjorddalen, western Norway: rock-slope instabilities and rock avalanches in a changing landscape following the melt down of the Scandinavian ice sheet / Markus, T. Schleier. Gutachter: Joachim Rohn ; Reginald, L. Hermanns". Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2016. http://d-nb.info/1083259571/34.

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17

Greif, Vladimir. "Study on the effects of various boundary conditions on the failure mechanism in natural rock slopes". 京都大学 (Kyoto University), 2003. http://hdl.handle.net/2433/149082.

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Knapp, Sibylle [Verfasser], Michael [Akademischer Betreuer] Krautblatter, Jürgen [Gutachter] Geist, Michael [Gutachter] Krautblatter y Flavio [Gutachter] Anselmetti. "Rock-Slope Failures Impacting Lakes : Frequency, Magnitude and Interactive Processes Deciphered From Lacustrine and Terrestrial Deposits / Sibylle Knapp ; Gutachter: Jürgen Geist, Michael Krautblatter, Flavio Anselmetti ; Betreuer: Michael Krautblatter". München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1226934331/34.

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19

Blanchet, François. "Etude géomécanique de glissements de terrain dans les argiles glacio-lacustres de la vallée du Drac". Phd thesis, Grenoble 1, 1988. http://www.theses.fr/1988GRE10117.

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Nous avons etudie un glissement de terrain affectant le lotissement du mas d'avignonet, situe sur la rive gauche de la retenue du monteynard. Une campagne de reconnaissance in situ comportant sondages, releves geologiques, indices de mouvement, mesures inclinimetriques, topographiques et piezometriques nous a permis de mettre en evidence plusieurs surfaces de deformations. On propose des mecanismes probables de rupture de ces glissements; on definit leur geometrie et on evalue les valeurs residuelles des caracteristiques mecaniques a la rupture des argiles litees, formation a l'origine de nombreuses instabilites dans la region. On analyse la stabilite du lotissement ainsi que le role des seismes sur la stabilite a long terme du versant

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20

吳東嶽. "Progressive Failure of Soft-Rock Slope - Mechanisms and Modeling". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/18305803652589472902.

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21

Chen, Kuan-Chih y 陳冠志. "Analysis and Application of Toppling Failure of Anaclinal Rock Slope". Thesis, 2000. http://ndltd.ncl.edu.tw/handle/13156714035242749895.

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碩士
中原大學
土木工程學系
88
Because of steep topography, inferior geological condition and severe climate, slope instability is always a serious problem in Taiwan. Common failure modes of natural slopes are composed of sliding (planar, wedge and circular), toppling, rock-falling and flow. Toppling failure always occurs in anaclinal slopes of layered rock masses, such as thin-bedded sedimentary rocks, foliated metamorphic rocks, and those of one single joint set or hexagonal joint pattern. Such a failure is initiated from the toe region of slope due to undermining of erosion or excavation, leading to the progressive down-slope movement of slope mass above. Because its failure process is quite long, toppling has not been well noticeable in Taiwan. The objective of this thesis is to study the toppling behavior of two-dimensional rock slopes with "block toppling mode". The main analysis tool used is the limit equilibrium method-based "TOP" code, which was derived from the works of Goodman and Bray, and was then extended by Ke. In the parametric study of a regular slope profile, the influence factors under investigation include the slope angle, the base angle of failure surface, the width of rock block, joint dip, and the joint friction angle. The base friction machine first manufactured in Taiwan was also used to perform model tests of a series of toppling slope profiles, with test results being compared with the outcomes of TOP and DDA codes. Finally, two rock slopes along the Northern Cross-Island Road were selected for case study. The results of parametric study indicate that: 1) the required (limiting) friction angle for slope stability and the required support force at the toe of slope both increase with the slope angle; 2) the influence of the base angle of failure surface on support force becomes higher at the larger joint dip; the population of toppling (sliding) blocks decreases (increases) with the base angle of failure surface; 3) the required friction angle and the required support force both decrease with block width (0.5~2.5m); and the population of toppling blocks reduces with block width; 4) the required support force varies inversely with joint friction angle; the population of toppling (sliding) blocks increases (decreases) with the joint friction angle (greater than a certain value). The results of case study using TOP code indicated that the safety factors of the two slopes investigated are both slightly greater than 1.0, and some slope reinforcement should be employed.

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22

Chen, Chun-Chung y 陳俊中. "Strength Size Effect of Soft Rock and Field Test of Induced Slope Failure". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/29522873537599383443.

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碩士
國立交通大學
土木工程系
91
This research aims to study the size effect of the strength of soft rock and to model the progressive slope failure in soft rock formation. Undisturbed NX and HX size specimens were obtained for laboratory tests. A series of CU triaxial tests were carried out using a triaxial test device specially designed for soft rock. From test results, it appeared that the strength of a larger specimen is relatively lower than a smaller one. The existence of relatively more micro-fissures contained in a larger specimen may be responsible for the size effect. This research also attempted to study progressive slope failure in soft rock formation. The results of a field experiment of induced slope failure carried out by the Natural Hazard Mitigation Research Center, National Chiao-Tung University were adopted for modeling the progressive slope failure. Numerical simulation made use of the commercial code FLAC was carried out to model the field tests. The numerical model took into the strain-softening mechanism of soft rock into account. It was found that the progressive slope failure would initialize at certain tensile and shear yielding zones; the yielding zones tended to expand as a result of stress redistribution. It was demonstrated that the numerical simulation presented in this research could reasonably modeled the process and mechanism of the progressive failure of soft rock slope.

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23

Yang, Chih-Kai y 楊智凱. "The effect of clay seam on the failure surface development of rock slope". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/58881398686348957520.

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碩士
淡江大學
土木工程學系碩士班
103
In recent years, dip slope often create major damage and failure surface always development along shale. When slope slide, we can estimate landslide''s shear strength by back calculation. But back calculation of the shear strength different from lab test of the shear strength. Dip slope have bedding structures, then layers always have clay layer or seam by bedding shear. In this study, we against clay seam and failure surface development, research the effect of clay seam on the failure surface development of rock slope. Hoping to find better interpretation of back calculation of the shear strength different from lab test of the shear strength. And research slope failure factors at 3.1K of the Third Freeway in Taiwan. In this study, we research the effect of clay seam on the failure surface development of rock slope through numerical analysis. Research the effect of clay seam on the geometric properties and shear strength, then use gravity increase method to observed failure surface development. The following conclusions are drawn：(1)Pointed out in different geological to investigate the effect of clay seam on the failure surface development of rock slope. Clay seam by bedding shear and shale soften by water is more important on slope stability. (2)Use gravity increase method by FLAC gradually change acceleration of gravity of material, can quick observation the failure surface development of rock slope. (3)Clay seam on the geometric properties can influences slope stability and failure surface development. Failure surface slide position will change by clay seam position. When clay seam on slope toe will be most danger. Slop have clay seam will influence slope stability, but change thickness of clay seam will not influence slope stability. Change dip of clay seam will influence failure surface development, but not influence slope stability. (4)Change shear strength of clay seam will influence slope stability and failure surface development. When C/R ratio is higher, failure surface will be more shallow and circular failure. When C/R ratio is lower, failure surface will be more deep and planar failure. Soften friction angle on clay seam will more sensitive than soften the cohesion on clay seam. (5)Research slope failure factors at 3.1K of the Third Freeway in Taiwan. Analysis results are now similar to actual place. Use gravity increase method by FLAC can observed the failure surface development.

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24

Dlamini, Welile Khulile y 賴薇麗. "Effects of Rapid Drawdown on a Rock Slope Using the Hoek-Brown Failure Criterion". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/58g4r7.

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碩士
國立臺灣科技大學
營建工程系
107
Reservoir slope stability under drawdown condition is always important for reservoir designs. During rapid drawdown, the water level is reduced which allows the excess pore pressure to be generated. Therefore, it is possible to cause the slope to be unstable. Conventionally, the Mohr-Coulomb failure criterion is the most commonly used failure criterion to estimate the factor of safety for reservoir slopes. Morgenstern produced some stability charts, which are used in practice to date. In this study, analyses of rock slope rapid drawdown are performed by using the limit analysis method, and the nonlinear Hoek-Brown failure criterion was used in the analysis. Limit analysis employs the lower bound and upper bound theorems to give rigorous bounds of the true solution. The finite element program OPTUM G2 was used to study the effects of rapid drawdown on a fully submerged rock slope, using the Hoek-Brown failure criterion. Various slope heights, unit weights were analyzed using the Hoek-Brown parameters to find their lower bound solutions. The results obtained presented in the form of stability charts and tables.

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25

Huang, Wen-Sung y 黃玟菘. "A Study of Toe-excavation Induced Failure Process for a Dip Slope with Rock Anchorage". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/64260148149349192005.

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碩士
國立臺灣大學
土木工程學研究所
100
On April 25, 2010, without rainfall and earthquake triggering a massive landslide (200000 m3) covered a 200m stretch of Taiwan’s National Freeway No. 3, killing 4 people, burying three cars and destroying a bridge. The failure mode appears to be a dip-slope type failure occurred on a rock anchorage cut slope. Based on the investigations and the numerical analysis in this study, the toe-excavation at this dip-slope in 1998 was the most crucial factor. Although the excavated area had stabilized soon with rock anchors and backfills. The strength of rock mass had great effect on the stability of dip-slope after backfills. The strike of Tertiary sedimentary strata is northeast-southwest and dip 12˚ ~15˚ toward southeast. Considering the strength of sliding layer had reduced from peak to residual strength which was caused by the disturbance of excavation, the limit equilibrium method (LEM) analysis was utilized in the back analysis at first. The results showed the stability condition of slope approached the critical state (F.S.≈1). The efficiency reduction of rock anchors and strength reduction of overlying stratum (sandstone) had been considered in following analysis. The results showed the unstable condition (F.S. <1). This study also utilized the result of laboratory test, geological strength index(GSI) and finite difference method (FDM, FLAC 5.0) to discuss the failure process The analysis indicated that the incremental load of anchors have similar tendency comparing to the monitoring records in toe-excavation stages. This result showed that the strength of the sliding layer was significantly influenced by toe-excavation. The numerical model which calibrated with monitoring records in toe-excavation stage was used to discuss the failure process after backfilling. The efficiency reduction of rock anchors had less impact on the development of sliding surfaces. But the development of sliding surfaces were significantly influenced by the strength reduction of the rock mass。The sliding surface gradually developed from the toe of the dip-slope to the top of the dip-slope and the stability of the slope became more unstable in the process of rock mass strength reduction .

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26

Chen, Hsiou-Ming y 陳曉明. "A Study on Slope Failure Mechanisms and Mitigation of Werthering Sedimentary Rock in Southren of Taiwan". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/49861986202798754362.

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碩士
國立臺灣科技大學
營建工程系
90
A Study on Failure Mechanisms of Weathering Sedimentary Rock in Southern 0f Taiwan and Mitigation Thesis Advisor : Hung - Jiun Liao Graduate Student : Hsiou — Ming Chen ABSTRACT This case study is regarding for Second Freeway, Tainan section of South — West of Taiwan, that is built on the formations of soft sand stone and mudstone sedimentary rock, and in the raining season, the slope surface often has the minor shallow failure and the traditional limit equilibrium analysis of rock slope failure could not predict the happening of the phenomenon, Therefore it is difficult to mitigate this problem. In the process of study, use the records of basic physics of soft rock strength, engineering character and type of possible failure, but mainly use the choice of different rock strength, strength of interface and ground water level change as the input parameters for numerical and computer programming analysis, which are used to analysis (130 combinations) the deformations of the bedding and slope surface, then compare with the analysis results of relative shear stress shading and plastic point, the comparison shows that reduction of the rock strength due to the pressure release, during the construction is little more than test residual strength and also the reduction of the rock strength and the strength of bedding is coincidental. Meantime, after the rock slope are excavated the tension stress are concentrated obviously at the cutting face, the edge of berm, the lower part of earth anchor plate and the top of slope and these areas we are studying, although we adopt the earth anchor steady method and obviously, it is no improvement, therefore we conclude that these are the main reasons for the failure. In order to increase the lateral confine effect to improve the area with tensile stress was concentrated, the soil nail reinforcement method is adopted and from the results of the analysis, it shows the confine effect and same time the displacement of slope surface is correspondingly. Furthermore, it is important to mitigate the erosion of the soft rock slope, after study the methods for slope protection from rain and find that for a long term protection, the soil binder frame grid protection system is the best solution. Summarize the results of the study of steady and slope erosion and incorporate with the concept of ecological engineering to draft an improvement plan, also this plan has not been validated, but based on the study by years experience it should be a practical and economic plan, meantime, it also retain the environment and room for ecological evolution of the future plant.

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27

JHANG, JIA-WEI y 張嘉偉. "A Numerical Study on the Toppling Failure of Anti-dip Rock Slope by Discrete Element Method". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/jeepc5.

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碩士
國防大學理工學院
軍事工程碩士班
107
Taiwan is located at the junction of the Eurasian plate and the plate of the Philippine Sea Plate. It is bulged by the plate pushing, forming a topographical condition with few mountains and flat land. The loss of life and property caused by sloping land disasters is not uncommon. Generally speaking, the slopes caused by dip slope are common. The scale of the disaster is relatively large, and the damage loss is also serious. The research on slope disasters is mainly based on dip slope. However, in terms of hazard, the sliding scale of anti-dip slope is small, and it is unstable under the same scale slope condition. The regional density is relatively high and the frequency of occurrence is high. According to the Free Time 2017 data, during the 2016 period, there were as many as 249 sporadic rocks in the Suhua Highway. Therefore, the anti-dip slope disaster is also a research topic that cannot be ignored. In order to understand the development trend of anti-dip rock slope toppling failure, this study explores the anti-dip rock slope (UDEC) by Hoek and Bray monolithic toppling basic theory and anti-dip rock slope damage type classification. The -dip rock slope geometry factor (slope dip, layer dip, block size, the block width to height ratio) and joint characteristics (joint surface friction angle) may develop a toppling failure behavior pattern. Through the simplification of material properties, the toppling failure behavior pattern caused by geometric factors and joint characteristics of anti-dip rock slope is only discussed under the condition of material deformation behavior. According to the systematic parameters, according to the simulation results, when anti When the slope angle of the -dip rock slope is 56.6°, the failure type is mostly Flexural toppling, and when the slope angle is 80°, the instability type is differentiated according to the difference between the rock block size and the aspect ratio. Block topples or Block-Flexural toppling failure, the geometrical conditions that may lead to Flexural toppling, Block topples, and Block-Flexural toppling behavior is simultaneously aggregated by simulation results.

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28

Kampherm, Tanya Sandra. "Landslides triggered by the 1946 Ancash Earthquake (Peru) and geologic controls on the mechanisms of initial rock slope failure". Thesis, 2009. http://hdl.handle.net/10012/4233.

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The 1946 M7.3 Ancash earthquake triggered a large number of landslides in an epicentral area along the continental divide in the Andes of Peru. Reconnaissance reports by Silgado (1947, 1951), Heim (1949) and Rüegg (1950) published shortly after the earthquake describe some of the landslides, but lack any detailed documentation. A review of literature, field traverses, aerial photograph interpretation and GIS mapping, identified 45 landslides inferred to have been triggered by the event. The cumulative volume-frequency plot shows a strong power law relation, similar in form to that derived for landslides triggered by the 1994 Northridge earthquake (Harp and Jibson, 1995). Data for the Ancash earthquake plots near the regression line calculated by Keefer (1994), and modified by Malamud et al. (2004), for earthquake moment magnitude vs. total volume moved by landslides during the earthquake. A denudation (average surface lowering) of 76 mm and a denudation rate of 0.00585 mm/yr was estimated for the area over which the earthquake-triggered landslides occurred. Rock avalanches constituted 83% of the landslides which involved Cretaceous limestones interbedded with shales. Rock slope failures were common on slopes with a southwest aspect, an orientation corresponding to the regional dip direction of major planar structures in the epicentral area. In valleys oriented transverse to the NW-SE structural trend of the epicentral area, south-westerly dipping bedding planes combined with orthogonal joint sets to form numerous wedge failures. Three rock avalanches were analysed using conventional wedge failure criteria. Two of the rock avalanches which did not satisfy conventional criteria were utilized to develop a new criteria, i.e. stepped wedge criteria. Stepped wedge failure involves wedge movement along a stepped line of intersection formed by a nearly-vertical discontinuity, striking roughly parallel to the slope, and the conventional line of intersection formed by the bedding and orthogonal joint set. The nearly-vertical discontinuity forms the essential backscarp needed to facilitate stepped wedge failure. Additional characteristics of stepped wedge failure were also distinguished based on the wedge failures studied in the epicentral area of the 1946 Ancash earthquake.

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29

Lee, Chun-Ming y 李春明. "Stability of rock slope with non-structural control failures". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/18155427939015247702.

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碩士
國立中央大學
應用地質研究所
92
Stability of rock slope with non-structural control failures is studied in this thesis. Based on Non-linear Hoek-Brown failure criterion (2002), cohesion c' and frictional angle of the rock slope for different height (different stress range) are determined in conjunction with Geological Strength Index GSI. The maximum excavation angle (FS=1) with non-structural control failures of rock slope for different height can be evaluated using Janbu slope-stability chart. Consequently, GSI-based slope performance curves are constructed. The important results are summarized as follows: (1) Rock mass strength parameters are functions of stress range. Therefore, the height of rock slope should be taken into consideration for evaluating the maximum excavation angle. (2) Unconfined compressive strength of intact rock is a primary factor for evaluation of the maximum excavation angle with non-structural control failures. Relatively, the effect of material constant on the maximum excavation angle is minor. (3) Disturbance of excavation reduces the rock mass strength. The lower the GSI is the effect is more predominant. (4) GSI-based slope performance curves, taking the intact rock strength and material constants into consideration, are useful for evaluation the maximum excavation angle of rock slope.

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30

Li, Ming-Han y 李明翰. "Study of Toppling Failure of Rock Slopes along Taiwan Highway No. 14". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/yaktga.

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碩士
朝陽科技大學
營建工程系碩士班
91
Abstract Because of steep topography, inferior geological condition and severe climate, slope instability is always a serious problem in Taiwan. Common failure modes of rock slopes are composed of planar, wedge, toppling and circular. Toppling failure always occurs in anaclinal slopes of layered rock mass, such as thin-bedded sedimentary rocks, foliated metamorphic rocks and those of one single joint set. Because its failure process is quite long, toppling has not been well noticeable in Taiwan. Among the types of slope failures, the number of damages due to rock falls and toppling failures was ranked the second during 921 earthquake. Therefore, had to understanding the failure of toppling of rock slopes. Numerical analyses using UDEC (a program based on distinct element method) will be used to analyze two rock slopes of the toppling that on Highway 14 to understand the failure mechanisms. The Highway 14 chosen for illustrative purpose is located in the middle part of Geologic Region, and its route is mainly covered by slate and argillite. The results of analyses using UDEC indicate that: the failure modes of rock slopes are correspond to erosion or excavate toe of slopes on case 1, and rock slopes was toppled by weathering and an overburden load on case 2. The hardness rock slopes were neither plastic deformation nor tend to toppling, that were different from weak slopes of failure modes. When Rock Bridge of length, Rock Bridge of continuity and an overburden load to increase, friction angle of joints of rock slopes to increase for stable. The results of parametric study indicate that : when Rock Bridge of length less then 4m and Rock Bridge of continuity between 30%~70%, an overburden load is effect more then Rock Bridge of length and Rock Bridge of continuity. When Rock Bridge of length greater then 6m and Rock Bridge of continuity between 30%~70%, the Rock Bridge of length and Rock Bridge of continuity is effect more then an overburden load. Keywords: Toppling failure, UDEC, Rock Bridge, continuity, an overburden load

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31

Chen, Cheng-Jung y 陳政融. "Failure Analysis of Jointed Rock Dip-Slopes Based on Rough-Joint Model". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/z356a4.

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碩士
國立臺灣大學
土木工程學研究所
105
There are many dip slopes in Taiwan. The failure of dip slope often has rapid collapse and sliding that causes significant casualties. Rock slope usually contains discontinuities such as bedding, foliation, joints, which are the key factor of rock slope stability. Thereforce, the discrete element analysis is a powerful method to investigate the stability of dip-slope. In this study, PFC2D software is choose as the discrete element method to analyze rock dip-slope. Use the rough-joint model which developed by Chiu (2016) to simulate the weak plane and then analyze the failure mechanism of rock slope. This study first verity out the accuracy of rough-joint model by numerical direct shear test, and then simulate laboratory direct shear test with artificial rock sample to investigate the applicability of this model. Finally, set up a numerical rock slope model with in-situ data and then compare it with practical condition to discuss about the application of the rough-joint model on rock slope failure analysis. In the part of rough-joint model verification, substituting the same parameter into Barton’s model and rough joint model can get a Barton’s theory curve and data of simulation. After comparison with each orther, we can find that rough-joint model can represent Barton’s model reasonably, and it let PFC2D express weak plane more precise. For the actual case-Wulai Zhongzhi, take the weakness of joints and rock material as sliding factor. The results of simulation are similar to practical condition and it indicate that rough-joint model can simulate rock slope well.

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32

Wu, Chun-Jung y 吳俊融. "Failure Analysis of Jointed Rock Slopes Based on a Modified Smooth-Joint Model". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/22880678145865119601.

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碩士
國立臺灣大學
土木工程學研究所
103
Rock slope often contains discontinuities such as joints, which is the key factor of rock slope stability. Conventionally, the limit equilibrium analysis and continuum numerical analysis are most used method for stability of jointed rock slope. However, the mechanical behavior of joint surface influence the sliding failure of rock block and massive transfer of block in jointed rock slope extremely. Therefore, the discrete element analysis which can consider the mechanical behavior of discrete block is an effective way to investigate the stability of jointed rock slope. In this study, PFC3D software is choose as the discrete element analysis tool, however, PFC is over-simplify in simulate joint surface behavior, thus it cannot react the mechanical behavior of roughness joint surface. Therefore, this study simulates the mechanical characteristic of joint surface through the improved method - Modified Smooth-Joint Model (MSJ model) which is developed by our research team. The MSJ model is based on Barton''s shear strength criterion, the mechanical behaviors are determined by various joint parameters. This study first verify out the accuracy of MSJ model by numerical direct shear tests, then we construct a simple rock slope model to discuss the relationships between limit equilibrium analysis and joint parameters, and then the influence of joint continuity is investigated, finally discuss about the application of the MSJ model on rock slope failure analysis. In the part of MSJ model verification, we first to examine the reliability of intact rock micro-parameters through the simulation data of uniaxial compress test; then the rationality of joint parameters are verified by the results of direct shear test; finally, the simulation results of direct shear test and Barton''s shear strength model are compared to ensure that they are equal, and the SJ model is treated as the control group. The comparison shows MSJ model can reasonably represent the trend of Barton''s model which shows friction angle is correlate with normal stress, while SJ model cannot point out this important characteristic in roughness joint. In the section of simple rock slope analysis, trapezoid slope with single joint is used in the simulation. The first step is changing the joint friction angle parameters to analyze the relationship between the joint friction angle and dip angle according to the limit equilibrium theory; second, the revised MSJ model is used to investigate the spatial distribution of friction angle to recognize the influence of normal stress acted on joint surface; finally, the continuous joints are alter to discontinuous joints to simulate the effect of rock bridge, and then sequentially investigate the influence of joint persistence, intact rock strength and rock bridge type to the rock slope stability through failure analysis of rock slope. According to the simulation results of simple rock slope, there are some conclusions and suggestions of the MSJ model. The simulation results show that even joint friction angle is lower to dip angle, the slope is not necessarily to slip in numerical rock slope. We suggest that three-dimensional limit equilibrium analysis can be adapted in future to correct the settings of numerical model; joint friction angles is vary with the distribution of upper block weight, this feature shows the mechanical behavior of roughness joint is influence by normal stress; if joint surface is discontinuous, the crack distribution are correlate to the length and type of rock bridges, and the failure of rock bridge will cause upper block to slide. We recommended that MSJ model can be used to simulate real rock slope in the future, and exploring the complex mechanism of jointed rock slope failure to evaluate the analysis and design of geo-engineering.

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33

Hsieh, Pei-Chen y 謝沛宸. "Characterization of Rock Mass on High-steep Obsequent Slopes and Bearing Failure Due to Different Strength of Rock Layers". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/v36pnu.

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碩士
國立臺灣大學
土木工程學研究所
106
Rockfall failure and toppling failure are usually considered as the typical types of obsequent slopes failure. However, some field investigation cases on coastal area in northern Taiwan show that bearing failure could also be found in obsequent slopes. These cases are composed of a competent layer lying on an incompetent layer, or called the cap rock structure. The first part in this research is developing a method to describe overhang topography and estimate the size of overhang part. The contours are computed based on dip direction of cliff from point cloud produced by UAV photogrammetry. Therefore, the position and volume of overhang part can be calculated. Also, joint sets are identified by point cloud. The second part is to perform a small scale sandbox experiment to simulate bearing failure mechanism of the obsequent slope. The sandbox experiment demonstrates that bearing failure on obsequent slopes could be classified into two types, sliding (type I) and toppling (type II). The PFC3D model is used to analyze the factor, including the dimension of cap rock block and strength of rock layers, of bearing failure on obsequent slopes. The results show that the dimension of cap rock block and the dip angle of bedding are key factors of the failure type, sliding (type I) or toppling (type II). In addition, the ratio of normal stress of cap rock block to strength of incompetent layer is the key factor to decide whether the failure will happen or not.

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34

Shih, Kai-Yuan y 施開元. "Windowization and Application of a Topping Failure Analysis Program of Anaclinal Rock Slopes - TOP". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/84515575322278833530.

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碩士
中原大學
土木工程研究所
90
Because of its inferior geological conditions and environmental factors, intense geological hazards like slope failures have been a serious issue in Taiwan. Among several modes of slope failure, toppling always happens in the anaclinal rock slopes composed of one single steeply-dipping discontinuity set. Toppling is one type of progressive failures, in which the disturbed zone will gradually extend inward the slope after initiation. Accordingly, the analysis and the corresponding remedy of toppling failures really deserve a further investigation. The toppling failure mechanism used to be analyzed by the kinematics analysis, limit equilibrium method (LEM), model testing, and discrete numerical analysis. Among them, the Goodman & Bray stability analysis program as one kind of LEM provides a good estimator for block-type toppling failures, followed by a DOS-based program, TOP being written in 1994. However, it is in-convenient for TOP to deal with I/O matters in a DOS environment like other DOS-based programs. The primary goal of this thesis is to rewrite the TOP code into a graphic-user-interface (GUI) program, named TOPWin. The corresponding coding framework was presented in detail herein, which might provide a valuable reference for wondowizing the other DOS-base programs. The completed TOPWin code was then adopted to perform a sensitivity study of four parameters (slope angle α, base angle δ, block width w, and joint dip angle s) on the limiting friction angle fL of a regular rock slope. About 4000 sets of (α, δ, w, s, fL) were generated and subsequently used by a Back-Propagation Neural Network (BPNN) program to study their significance sequence and to establish a simple predictive formula of fL. Finally, three field case studies were conducted to illustrate the convenience, speediness, and flexibility of the TOPWin code.

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35

Mercer, Kenneth George. "Investigation into the time dependent deformation behaviour and failure mechanisms of unsupported rock slopes based on the interpretation of observed deformation behaviour". Thesis, 2008. http://hdl.handle.net/10539/5400.

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36

Chen, Chih-Hao y 陳志豪. "A study on the Toppling Failure of Rock slopes along the Northern Cross-Island Road". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/05728119668349839887.

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碩士
中原大學
土木工程研究所
89
Because of its inferior geological conditions and environmental factors, intense geological hazards like slope failure have been a serious issue in Taiwan. Among several modes of slope failure, toppling always happens in the anaclinal rock slopes composed of one single steeply-dipping discontinuity set. According to rock characteristics and discontinuity spacing, toppling failure can be classified further as block, flexural, and block-flexural types. Failure of this kind often initiates at the toe of a slope, and gradually propagates upslope, causing a progressive type of failure. The main objective of this thesis is to establish a comprehensive methodology of analyzing the stability of rock slopes mainly involving the block-toppling mode, by taking the cases along the Northern Cross-Island (NCI) Road for example. Three different kinds of stability analyses are used in this thesis, i.e., kinematics analysis (KA), limit equilibrium method (LEM), discontinuous deformation analysis (DDA). KA is conducted merely based on the three-dimensional orientation data of rock slope and discontinuity, and it is a simple tool to identify the toppling potential spots over large areas. The LEM used is the TOP code, in which a rock slope is idealized as a system of rigid columnar blocks formed by one discontinuity set, and it can be utilized to quickly determine the safety factor (FS) of a slope as well as the support force at the toe (P0). DDA is otherwise a sophisticate discrete analysis which deals with the complex interactions of multiple deformable blocks, and it can yield more precise estimates of FS and P0 based on the computed displacement history of selected control points. According to the methodology proposed in this thesis, KA, TOP, and DDA are adopted to prescreen a number of sites of interest, to calculate the FS values of these prescreened sites, and to determine the P0 values and disturbed zone of some critical sites, respectively. The NCI Road chosen for illustrative purpose is located in the northern part of Shen-Shan Geologic Region, and its route is mainly covered by inter-bedded sandstone and shale. By reviewing previous geological records and performing KA, ten sites were selected along the road, followed by field data collected including the corresponding idealized profiles of rock slopes. The analysis results of TOP code show that the FS values of these sites vary from 1.00 to 1.15, and three sites with the lowest FS values match their field observations, i.e., continuous toppled mass near their toes. DDA simulation results indicate that the P0 values of these sites for a FS of 1.20 are in the magnitude of 10ton/m, and no further horizontal excavation at the toe is allowed for every site under investigation.

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37

Goodman, Hubert John. "The nature of failure through the intact materials in the step joint mechanism for rock slopes". Thesis, 2015. http://hdl.handle.net/10539/16683.

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38

Chiu, Yun y 邱筠. "Establishment of Environmental Risk Model for the Potential Slope Failures Along the Highway Through Soft Rock Region in Southern Taiwan". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/79157888853398885197.

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Resumen

碩士
國立屏東科技大學
土木工程系碩士班
94
Slope failures and landslides at soft rock region in southern Taiwan have not only been recognized as a serious issue but also a major concern by the public in Taiwan. Weak geological structures, uneven distribution of rainfall intensity, steep geomorphology and intensive human activities have been identified as predominant factors to the slope failure, landslide, debris flow, and rock fall in the region. These disasters mentioned usually endanger public facilities and human life through the Southern No.3 Freeway and Tai-3 highway. This study investigates the detrimental characteristics of damaged slopes along the highways by using global positioning systems (GPS), geographic information systems (GIS) and remote systems (RS) techniques. Data related to the slope failures were collected from field investigations and filed and analyzed by using GIS technology combined with statistic analysis. Both Back-Propagation network method and multivariate analysis are used to establish a risk assessment model. The model is then combined with GPS/GIS/RS integrated technology to automatically map the sections with different potentially endangered level along the freeways. Based on the field investigation, two slopes were chosen to conduct a dynamic simulation of the failure processes. All results above can be used to build up a GIS database system concerning slope damages along highways in the region. The database is expected to be helpful in optimizing the designing and planning of slope protection measures along the roads in the soft rock region in southern Taiwan.

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Tesis sobre el tema "Rock slope failure"

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