Slope stability is an important aspect of geotechnical engineering. Input parameters for the analysis are the governing factors and they must be determined accurately and precisely. Field investigations, laboratory testing and back analyses are vital instruments for the input parameters. This study presents the results of slope stability analysis for the soil slopes at Elbistan-&Ccedil / &ouml / llolar lignite mine. After executing the drilling programme, samples taken from the drilling work, delivered to soil mechanics laboratory for testing. The basic input parameters, namely cohesion and friction angle determined at soil mechanics laboratory were compared to the parameters obtained from back analysis of a large scale slope failure. Input parameters for the analysis are determined by this way. After determining the input parameters, slope stability analyses were carried out both for the permanent and temporary slopes in AfSin-Elbistan lignite basin, &Ccedil / &ouml / llolar sector. The effect of ground water on the stability of slopes was investigated in detail and maximum safe slope angles were determined for different water levels. For limit equilibrium analysis, Rocscience SLIDE software, for finite difference analysis in 3-D, Itasca FLAC3D was used. In the limit equilibrium analyses both circular and composite failures were considered. Shear strength reduction method is used for the finite difference method. The results between limit equilibrium and 3-D finite difference methods were compared. When the failure surfaces obtained from the finite difference analyses were imposed to limit equilibrium analysis, computations are resulted in lower factor of safety values for limit equilibrium analysis.

Shear strength characterization of discontinuities is an important concept for slope design in discontinuous rocks. This study presents the development of a methodology for implementing Barton-Bandis empirical shear strength failure criterion in three dimensional distinct element code, 3DEC, and verification of this methodology. Normal and shear deformation characteristics of discontinuities and their relations to the discontinuity surface characteristics have been reviewed in detail. First, a C++ dynamic link library (DLL) file was coded and embedded into 3DEC for modelling the Barton-Bandis shear strength criterion. Then, a numerically developed direct shear test model was used to verify the normal and shear deformation behaviour with respect to empirical results of the Barton-Bandis shear strength criterion. A three dimensional simple discontinuous rock slope was modelled in 3DEC based on Barton-Bandis shear strength criterion. The slope model was first utilized by Mohr-Coulomb failure criterion. Then, with the use of the new model developed here, the effects of the discontinuity surface properties on shear strength were introduced to the slope problem. Applicability of the developed model was verified by three large scale real case studies from different open pit lignite mines of Turkish Coal Enterprises (TKi), namely Bursa Lignites Establishment (BLi) &ndash / 2 cases and &Ccedil / an Lignite Establishment (&Ccedil / Li). The results with the new model option, which allows users to use important discontinuity surface properties like joint roughness coefficient and joint wall compressive strength, compared well with results of previous studies using Mohr-Coulomb failure criterion.

Groundwater can be a critical issue to be considered in civil engineering, mining engineering and interdisciplinary fields. Karstic structures and aquifers enclosing groundwater are potential risks in case they are not studied in detail. Enclosed groundwater can result in floods at pit bottom or can cause instabilities of permanent pit slopes. This study is about analyses of flooding possibility at the pit bottom and possible instabilities of pit slopes in the Elbistan-&Ccedil / &ouml / llolar open cast coal mine due to the presence of a karstic aquifer under the lignite formation. Thickness and permeability of the bottom clay formation under the lignite bed are necessary critical parameters for investigating a possible water rush from a confined aquifer in limestone formation underneath the bottom clay. These parameters were changed, and water flow quantities towards the pit bottom were determined by finite element models. Critical values of these parameters were investigated considering the lack of accurate site investigation information regarding the thickness and permeability of bottom clay. Possible strength loss, fracturing, and thus permeability increase in bottom clay due to a confined aquifer were studied. In flooding and slope stability analyses Phase2 software based on finite element method is used. Results of analyses showed that as reported thickness of bottom clay is around 120 m at the pit bottom and permeability values are in orders of magnitudes of 10-8 m/s, no serious flooding problems are expected to occur unless the thickness of bottom clay layer drops down to around 20 m, and the permeability of this layer reaches an order of magnitude of 10-5 m/s. Mechanical effects of confined aquifer on slopes and bottom clay displacements were investigated, and thus fracturing and failure possibilities of bottom clay and permanent slope were assessed. Slope and pit bottom displacements increased to meter levels for less than 60 m bottom clay thicknesses. Whereas 50-60 m bottom clay thickness can be critical for cracking, 20 m bottom clay thickness was found to be critical for water rush to the pit bottom. With reported bottom clay thickness of 120 m and with 25o slope angle permanent slope factor of safety was found to be 1.2, and this value was not effected unless clay layer thickness drops below 70 m levels. Higher than 32o overall slope angle there will be a risk of slope failure for permanent and production slopes, reflected by safety factors less than one, in the stability analyses.

The objective of this study is to investigate the stability problems in tailing (i.e. mine waste) dams. A tailing dam is an embankment dam (made of natural borrow or tailing material) constructed to retain slurry-like mining wastes that are produced as a result of operation of mines. In the last 30 years, the stability of tailing dams has drawn much attention as a significant number of tailing dam failures have been recorded worldwide. These instability problems caused significant loss of life and damage to property in addition to environmental hazards. In this study causes of failure of tailing dams and their stability problems are investigated with respect to their geometric and material characteristics. Seepage and stability of tailing dams are studied through limit equilibrium method and finite element method. The effects of uncertainties in material properties on the stability of tailings dams is investigated. Within this context, Kastamonu-Kure copper tailings dam is used as a case study and material properties are determined by laboratory tests.

Bryant and Eastern Canyon systems are located on the northwest Gulf of Mexico, and they are characterized by a very complex sedimentological history related to glacioeustatic cycles, river discharges, and interactions of depositional and halokinetic processes. Both canyon systems were active during the low sea-level stand of Oxygen Isotope Stage 6, and provided the pathways for the transport of enormous amounts of sediments on the continental slope and abyssal plain of the northwest Gulf of Mexico. Right after their abandonment, at the beginning of Stage 5, salt diapirs encroached into the canyons, and resulted in their transformation into a network of intraslope basins. The transformation of the canyons resulted in the generation of massive sediment failures. The mid-shelf (Stages 4 and 3) to shelf edge (Stage 2) lowering of the sea-level during the last glacial episode resulted in: 1) extensive river-sourced deposits on the outer shelf and/or upper continental slope that contributed in a seaward mobilization of the underlying salt masses, and 2) the generation of numerous gravity flows and turbidity currents on the outer shelf/upper continental slope. The seaward mobilization of the salt masses resulted in the oversteepening of the flanks of the basins, and consequently in the generation of numerous and massive sediment failures. The turbidity currents were confined on the intraslope basins of the upper continental slope, depositing their coarsest material. However, their most diluted upper and end members were able to continue their downslope propagation depositing characteristic fine-grained turbidites. The frequency of the turbidity currents was highly increased during the last glacial maximum (Stage 2), and three short melt-water pulses centered at 30.5, 36, and 52 ky B.P. The last deglaciation event is characterized by the development of a major melt water event that resulted in the deposition of distinct organic rich sediments, similar to the sapropels of the Eastern Mediterranean. At about 11 ky B.P. the melt water discharges of the North America switched from Mississippi River to St Lawrence Seaway, causing the domination of hemipelagic sedimentation on the continental slope of the northwest Gulf of Mexico.

Slope stability plays an important role in rock engineering. During the design, construction and post design phases of rock slope stability, engineers and geologists need to pay close attention to the rock conditions within the rock slope to prevent slope failures, protect employees and maintain economic profit. This dissertation is based on a general four step procedure to construct and maintain rock slope stability with confidence. These four steps include field investigations, material testing and rock strength database, slope modelling and slope monitoring. The author provides past, present and alternatives methods for each step for the introduced slope stability procedure. Specific topics within each step are investigated displaying results, recommendations and conclusions. Step one involves data collection during field investigations for rock slope design. Orientation of rock core during drilling programs has become extremely pertinent and important for slope stability and underground mining operations. Orientation is needed to provide essential data to describe the structure and properties of discontinuities encountered during the design process to understand favourable and unfavourable conditions within a rock slope and underground openings. This chapter examines and discusses the limitations and benefits of four methods of obtaining borehole discontinuity orientations from drilling programs including clay-imprint, ACT I, II, III Reflex, EZY-MARK, and OBI/ABI Televiewer systems. Results, recommendations and conclusions are provided in this study. During step two to maintain rock slope stability, a rock strength database was created and used to correlate and compare RQD values to rock abrasion, shear strength and other rock characterization methods. Rock abrasion plays a significant role in geotechnical design, tunneling operations and the safety of foundations from scour; however, rock abrasion can be used to develop higher confidence in important parameters such as RQD and hardness. More rock abrasivity research is needed to provide a more accurate and compatible method for all subsurface material properties used in mining and civil engineering projects. This report will provide simple correlations relating abrasion resistance to RQD, UCS, Geological Strength Index (GSI) and Rock Mass Rating (RMR) of metamorphic rock. Results, discussions and conclusions are provided. Step 3 to determine rock slope stability entails utilizing computer modeling to predict failure conditions and wear rock mass properties. Computer modeling and slope monitoring for rock slopes have become essential to assess factor of safety (FOS) values to predict slope instability and estimate potential failure. When utilizing computer models, the limit equilibrium method (LEM) provides FOS values according to force and moment equilibrium; the shear strength reduction (SSR) technique calculates FOS using stress- and deformation-based analyses. Currently, both methods are prevalent in the engineering industry and applied by geotechnical engineers to analyze and determine stability in rock slopes for mining and civil engineering projects. Slope modeling techniques are then used to observe slope conditions and predict when slope failure may occur (FOS = 1.0). Comparison, results and conclusions are presented. Lastly, the dissertation (step 4: slope monitoring) will investigate past studies of FOS comparisons, review calculation methods and provide procedures and results using remote sensing data. The main objective of the dissertation is to provide engineers with essential information needed to ensure high confidence in factor of safety predictions and how alternative methods can be utilized. Recommendations, future research and conclusions regarding FOS and slope monitoring are provided within the dissertation.

Traditional slope stability analysis and design methods, such as limit equilibrium method and continuum numerical methods have limitations in investigating three dimensional large scale rock slope stability problems in open pit mines associated with stress concentrations and deformations arising due to intersection of many complex major discontinuity structures and irregular topographies. Analytical methods are limited to investigating kinematics and limit equilibrium conditions based on rigid body analyses. Continuum numerical methods fail to simulate the detachment of rock blocks and large displacements and rotations. Therefore, there is an urgent need to try some new methods to have a deeper understanding of the open pit mine rock slope stability problems. The intact rock properties and discontinuity properties for both DRC and DP rock formations that exist in the selected open pit mine were determined from tests conducted on rock samples collected from the mine site. Special survey equipment (Professor Kulatilake owns) which has a total station, laser scanner and a camera was used to perform remote fracture mapping in the research area selected at the mine site. From remote fracture mapping data, the fracture orientation, spacing and density were calculated in a much refined way in this dissertation compared to what exist in the literature. Discontinuity orientation distributions obtained through remote fracture mapping agreed very well with the results of manual fracture mapping conducted by the mining company. This is an important achievement in this dissertation compared to what exist in the literature. GSI rock quality system and Hoek-Brown failure criteria were used to estimate the rock mass properties combining the fracture mapping results with laboratory test results of intact rock samples. Fault properties and the DRC-DP contact properties were estimated based on the laboratory discontinuity test results. A geological model was built in a 3DEC model including all the major faults, DRC-DP contact, and two stages of rock excavation. The built major discontinuity system of 44 faults in 3DEC with their real orientations, locations and three dimensional extensions were validated successfully using the fault geometry data provided by the mining company using seven cross sections. This was a major accomplishment in this dissertation because it was done for the first time in the world. Numerical modeling was conducted to study the effect of boundary conditions, fault system and lateral stress ratio on the stability of the considered rock slope. For the considered section of the rock slope, the displacements obtained through stress boundary conditions were seemed more realistic than that obtained through zero velocity boundary conditions (on all four lateral faces). The fault system was found to play an important role with respect to rock slope stability. Stable deformation distributions were obtained for k₀ in the range of 0.4 to 0.7. Because the studied rock mass is quite stable, it seems that an appropriate range for k₀ for this rock mass is between 0.4 and 0.7. Seven monitoring points were selected from the deformation monitoring conducted at the open pit mine site by the mining company using a robotic total station to compare with numerical predictions. The displacements occurred between July 2011 and July 2012 due to the nearby rock mass excavation that took place during the same period were compared between the field monitoring results and the predicted numerical modeling results; a good agreement was obtained. This is a huge success in this dissertation because such a comparison was done for the first time in the world. In overall, the successful simulation of the rock excavation during a certain time period indicated the possibility of using the procedure developed in this dissertation to investigate rock slope stability with respect to expected future rock excavations in mine planning.

The use of geosynthetics in landfill construction introduces potential planes of weakness. As a result, there is a requirement to assess the stability along the soil/geosynthetic and geosynthetic/geosynthetic interfaces. Stability is governed by the shear strength along the weakest interface in the system. Repeatability interface shear strength testing of a geomembrane/geotextile interface at low normal stresses suitable for capping systems showed considerable variability of measured geosynthetic interface shear strengths, suggesting that minor factors can have a significant influence on the measured shear strength. This study demonstrates that more than one test per normal stress is necessary if a more accurate and reliable interface shear strength value is to be obtained. Carefully controlled inter-laboratory geosynthetic interface shear strength comparison tests undertaken on large direct shear devices that differ in the kinematic degrees of freedom of the top box, showed the fixed top box design to consistently over estimate the available interface shear strength compared to the vertically movable top box design. Results obtained from measurement of the normal stress on the interface during shear with use of load cells in the lower box of the fixed top box design, raise key questions on the accuracy, reliability and proper interpretation of the interface shear strength data used in landfill design calculations. Tests on the geocomposite/sand interface have shown the interface friction angle to vary with the orientation of the geocomposite's main core, in relation to the direction of shearing. Close attention needs to be paid to the onsite geocomposite placement in confined spaces and capping slope corners, as grid orientation on the slope becomes particularly important when sliding is initiated. Attempts to measure the pore water pressure during staged consolidation and shear along a clay/geomembrane interface in the large direct shear device suggest that this interface is a partial drainage path.

En bergslänts stabilitet styrs av berggrundens egenskaper, så som sprickegenskaper och bergkvalité. För att uppnå önskad stabilitet i en bergslänt behöver de bergmekaniska parametrarna kartläggas och analyseras för att fastställa risker och stabilitetsåtgärder. Syftet med studien är att utvärdera kvalitén på bergteknisk data från digitalfotogrammetriska 3D-modeller genom att jämföra resultatet med manuella mätningar från konventionell kartläggning. Målet är även att utforska potentialen för användning av fotogrammetrisk 3D-modellering vid stabilitetsanalyser i bergslänter genom att utvärdera den bergtekniska analys som kan göras utifrån fotogrammetrisk data. Sprickmätningar framtagna från 3D-modellen visade sig ha samma kvalité som manuella mätningar tagna enligt konventionell metod. Den UAS-baserade fotogrammetrin kan dock inte ersätta den konventionella analysen helt vid stabilitetsanalyser men kan användas som ett kompletterande verktyg i bergtekniska undersökningar. Fotogrammetrin möjliggör datainsamling från ett säkrare avstånd vilket minskar riskmomenten som den konventionella metoden medför vid arbete i fält. Den digitala metoden visade sig även ha fler fördelar såsom möjligheten av kartläggning och analysering framför datorn för mindre tids- och kostnadskrävande moment, digital datalagring samt att slänter med begränsad åtkomst kan karteras. / The stability of a rock slope is controlled by the rock’s mechanical properties, such as rock quality and facets. To achieve the desired stability in a rock slope, the mechanical parameters need to be mapped and analysed to determine possible failures and decide necessary stability measures. The purpose of this study is to evaluate the quality of rock technical data from digital photogrammetry 3D models by comparing the result with manual measurements from conventional mapping. The goal is also to explore the potential uses of photogrammetric 3D models for rock slope stability analyses by evaluate the photogrammetric data. Facets extracted from 3D models were found to have the same quality as manual measurements. However, the UAS-based method cannot completely replace the conventional method but can be useful as a complementary tool. Photogrammetry enables the collection of data from a safer distance, which reduces workplace hazards that the conventional method entails. The digital method also proved to have more advantages, such as the possibility of digital mapping and analysing which is less costly and time-consuming, digital data storage and the possibility to access outcrops that can’t be mapped with manually measurements due to inaccessibility.

[pt] Esse trabalho tem como objetivo desenvolver um modelo determinístico transiente de previsão de escorregamentos planares em encostas, para escalas em nível de bacia hidrográfica (1:2000 a 1:5000). No modelo são aplicadas as teorias de Green-Ampt (1934) e de O Loughlin (1986), essa última utilizada no programa SHALSTAB (MONTGOMERY e DIETRICH, 1994), além da teoria talude infinito 2D e 3D. Também são considerados nas análises a não saturação do solo e os efeitos da vegetação. O evento estudado para aplicação e teste do modelo refere-se ao ocorrido em 1996, nas bacias do Quitite e Papagaio em Jacarepaguá, Zona Oeste do Rio de Janeiro. Além do mapeamento do fator de segurança nas bacias, também são gerados mapas com o escoamento superficial acumulado, e tenta-se correlacionar ambos com as cicatrizes que ocorreram no caso de estudo. / [en] The aim of this work is to develop a physically-based transient model for the prediction of planar landslides in natural slopes. The application scale of the model is for a hydrographic basin (1:2000 to 1:5000). The theories of Green-Ampt (1934) and O Loughlin (1986), the second one used in the SHALSTAB program (MONTGOMERY e DIETRICH, 1994), and the infinite slope 2D and 3D are used in the model. The effect of the unsaturation and the vegetation is also considered in the analysis. The case study for the test of the model is the 1996 event that took place in the Quitite and Papagaio basins, in Jacarepaguá, Zona Oeste of Rio de Janeiro. Besides mapping the safety factor in the basins, maps of the accumulated runoff were also generated. This work also tries to correlate the runoff as another factor that caused the landslides.