A pesquisa voltada para a retroanálise de taludes de mineração está se tornando cada vez mais importante. As dimensões das atuais cavas de mineração visam sempre obter a melhor relação entre custo, benefício e segurança. Isso exige que por vezes o trabalho ocorra próximo destes limites. Neste trabalho o estudo de retroanálise consiste em um talude misto composto por aluvião e rocha em uma mineração de carvão localizada no município de Arroio dos Ratos, RS. O objetivo foi realizar um estudo de retroanálise onde se utilizou dois métodos de análise método dos Elementos Finitos (MEF) e o método do Equilíbrio Limite (EL). A metodologia adotada foi dividida em três fases: uma etapa de campo, para coleta do material e dados geométricos do talude, uma etapa de laboratório para caracterizar todo o material e a última etapa computacional onde foram gerados os modelos e simulações numéricas através dos softwares comerciais da empresa RocScience, sendo eles o SLIDE e o RS2. Os resultados encontrados mostraram que a porção do talude composta por aluvião apresentava seis camadas intercaladas de areias bem graduadas e argilas de média a alta plasticidade. Em relação as simulações, observou uma diferença entre o MEF e EL devido ao grande número de camadas presentes no talude e a interação entre elas. Foram criados quatro diferentes cenários para observar o comportamento do talude, com presença e ausência de água. O MEF mostrou uma superfície de ruptura próxima a encontrada porem com a presença de água o Fator de Segurança (FS) sofreu uma grande depreciação. O EL considerou uma superfície de ruptura satisfatória, nas simulações com presença de água FS sofreu uma depreciação mínima mesmo com máxima saturação de água no talude. Apesar das diferenças ambos os métodos são confiáveis mas devem ser usados de forma adequado ao tipo de problema existente. Situações mais simples e com taludes mais homogêneos o EL trona-se mais indicado, para problemas de maior complexidades e interações entre camadas o MEF se mostrou satisfatório e com boa resposta. O resultados através do MEF se aproximaram mais da situação real encontrada em campo. / A research focus on retro analysis on mine slopes is becoming increasingly important. The dimensions of current mining caves aim to always obtain the best cost benefit ratio as well as the highest safety level. This demands that the work sometimes is done within these limits. In this paper the study of retro analysis is made up of a mixed slope composed of alluvial and rocks, in a coal mine in Arroio dos Ratos, RS. The goal was to carry out a retro analysis study using two analysis methods: The Finite Element Method (FEM) and Limit Equilibrium analysis (LE). The methodology adopted was split into three phases: a field stage for the sample collection and slopes geometric , a laboratory stage to classify all the material and a final computacional stage were model and numerical simulations were created by way of commercial software, Slide and RS2, by RocScience. The results showed that the portion of the slope composed of alluvium had six layers interspersed with well graded sands and high plasticity clays. The simulations observed a difference between the FEM and LE due to the number of layers present in the slope and the interaction among them. Four different scenarios were created in order to observe the behavior of the slope. The FEM presents surface failure similar to one found in the field. The LE always takes into consideration the overall critical surface which is not observed in the field, it also show high security factor levels above one 1.3 that does not reflect a real situation since the slope is collapsed. In spike of the differences, both methods are reliable but they must be used according to the existing problems. For simpler situations with homogeneous slopes LE is recommended while move complex problems and interactions among lawyers calls for FEM.

Submitted by Admir José Giacon Junior null (juniorgiacon@gmail.com) on 2018-03-06T14:12:14Z No. of bitstreams: 1 Análise probabilística da estabilidade de taludes via teoria da confiabilidade - GIACON JUNIOR - 2018.pdf: 4258233 bytes, checksum: 777c3f6fb0d3f477af5650ac6adc895a (MD5) / Approved for entry into archive by Maria Marlene Zaniboni null (zaniboni@bauru.unesp.br) on 2018-03-07T17:37:24Z (GMT) No. of bitstreams: 1 giaconjunior_aj_me_bauru.pdf: 4258233 bytes, checksum: 777c3f6fb0d3f477af5650ac6adc895a (MD5) / Made available in DSpace on 2018-03-07T17:37:24Z (GMT). No. of bitstreams: 1 giaconjunior_aj_me_bauru.pdf: 4258233 bytes, checksum: 777c3f6fb0d3f477af5650ac6adc895a (MD5) Previous issue date: 2018-01-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Devido às consequências negativas associadas à ruptura e deslizamentos de taludes, a análise de estabilidade desses assume uma parte primordial na área da engenharia geotécnica. A maioria dessas análises é realizada de maneira determinística, não incorporando as incertezas inerentes ao sistema. A constatação dessas incertezas em projetos de taludes associa-se a previsão de uma probabilidade de falha no desempenho de taludes quanto à segurança. Nesse contexto, esta dissertação busca avaliar a segurança de taludes através de uma abordagem probabilística, simulando taludes com geometrias e solos variados, verificando ainda a influência da elevação da posição do nível d´água. Para essa finalidade foram realizadas análises probabilísticas utilizando First Order Reliability Method (FORM) com base nos métodos de Equilíbrio Limite, através dos programas computacionais acadêmicos RASS (análises determinísticas) e RELgen (análises probabilísticas). Com base nos resultados, verificou-se que as superfícies críticas obtidas pelos métodos determinísticos podem não coincidir com as superfícies que apresentam a maior probabilidade de falha. Isto é verificado ainda na análise de inclinação da superfície do talude, em que inclinações apresentando fatores de segurança admissíveis, apresentaram probabilidades de falha não aceitáveis. Estas divergências são atribuídas às incertezas inerentes ao sistema. Sendo assim, as análises de estabilidade de talude baseadas apenas nos resultados de análises determinísticas não apresentam todas as variáveis presentes no contexto do projeto. Por fim, através dos resultados obtidos nesta pesquisa é possível inferir que a adoção da análise probabilística em projeto de taludes auxilia de uma forma consistente a avaliação da segurança dos taludes, contribuindo de maneira satisfatória na prática de projetos de engenharia geotécnica. / Due to the negative consequences associated with slope rupture and landslides, the stability analysis of these slopes plays an important role in geotechnical engineering. Most of these analyzes are carried out in a deterministic manner, not incorporating the uncertainties inherent to the system. The observation of these uncertainties in slope projects is associated with the forecast of a probability of failure in slope performance in terms of safety. In this context, this paper present research seeks to evaluate slope safety in a probabilistic manner, simulating slopes with varied geometries and soils, also verifying the influence of elevation of the water level position. For this purpose, were performed probabilistic analyzes using First Order Reliability Method (FORM), based on the Limit Equilibrium methods, RASS (deterministic analysis) and RELgen (probabilistic analyzes). Based on the results, it was found that the critical surfaces obtained by the deterministic methods may not coincide with the highest most probability surfaces to fail. This is still verified in surface slope analysis, where inclinations with acceptable safety factors presented probabilities of failure unacceptable. These divergences are attributed to the uncertainties inherent in the system. Therefore, slope stability analyzes based only on the results of deterministic analyzes do not present all the variables present in the project context. Finally, through the results obtained in this research it is possible to infer that the adoption of probabilistic analysis in slope design assists in a consistent way the assessment of slope safety, contributing in a satisfactory way in the practice of geotechnical engineering projects.

A pesquisa voltada para a retroanálise de taludes de mineração está se tornando cada vez mais importante. As dimensões das atuais cavas de mineração visam sempre obter a melhor relação entre custo, benefício e segurança. Isso exige que por vezes o trabalho ocorra próximo destes limites. Neste trabalho o estudo de retroanálise consiste em um talude misto composto por aluvião e rocha em uma mineração de carvão localizada no município de Arroio dos Ratos, RS. O objetivo foi realizar um estudo de retroanálise onde se utilizou dois métodos de análise método dos Elementos Finitos (MEF) e o método do Equilíbrio Limite (EL). A metodologia adotada foi dividida em três fases: uma etapa de campo, para coleta do material e dados geométricos do talude, uma etapa de laboratório para caracterizar todo o material e a última etapa computacional onde foram gerados os modelos e simulações numéricas através dos softwares comerciais da empresa RocScience, sendo eles o SLIDE e o RS2. Os resultados encontrados mostraram que a porção do talude composta por aluvião apresentava seis camadas intercaladas de areias bem graduadas e argilas de média a alta plasticidade. Em relação as simulações, observou uma diferença entre o MEF e EL devido ao grande número de camadas presentes no talude e a interação entre elas. Foram criados quatro diferentes cenários para observar o comportamento do talude, com presença e ausência de água. O MEF mostrou uma superfície de ruptura próxima a encontrada porem com a presença de água o Fator de Segurança (FS) sofreu uma grande depreciação. O EL considerou uma superfície de ruptura satisfatória, nas simulações com presença de água FS sofreu uma depreciação mínima mesmo com máxima saturação de água no talude. Apesar das diferenças ambos os métodos são confiáveis mas devem ser usados de forma adequado ao tipo de problema existente. Situações mais simples e com taludes mais homogêneos o EL trona-se mais indicado, para problemas de maior complexidades e interações entre camadas o MEF se mostrou satisfatório e com boa resposta. O resultados através do MEF se aproximaram mais da situação real encontrada em campo. / A research focus on retro analysis on mine slopes is becoming increasingly important. The dimensions of current mining caves aim to always obtain the best cost benefit ratio as well as the highest safety level. This demands that the work sometimes is done within these limits. In this paper the study of retro analysis is made up of a mixed slope composed of alluvial and rocks, in a coal mine in Arroio dos Ratos, RS. The goal was to carry out a retro analysis study using two analysis methods: The Finite Element Method (FEM) and Limit Equilibrium analysis (LE). The methodology adopted was split into three phases: a field stage for the sample collection and slopes geometric , a laboratory stage to classify all the material and a final computacional stage were model and numerical simulations were created by way of commercial software, Slide and RS2, by RocScience. The results showed that the portion of the slope composed of alluvium had six layers interspersed with well graded sands and high plasticity clays. The simulations observed a difference between the FEM and LE due to the number of layers present in the slope and the interaction among them. Four different scenarios were created in order to observe the behavior of the slope. The FEM presents surface failure similar to one found in the field. The LE always takes into consideration the overall critical surface which is not observed in the field, it also show high security factor levels above one 1.3 that does not reflect a real situation since the slope is collapsed. In spike of the differences, both methods are reliable but they must be used according to the existing problems. For simpler situations with homogeneous slopes LE is recommended while move complex problems and interactions among lawyers calls for FEM.

Recent tailings dam failures around the world have highlighted the real risk posed by undrained slope failures. Undrained failures are fundamentally different to drained failures in the sense that different mechanisms are involved (i.e. a slope may be stable against drained failure but unstable against undrained failure). Popular methods to assess the stability of slopes against undrained failure involve the use of limit equilibrium analyses with both drained and undrained strengths assigned in the same analysis. A potential shortcoming of these methods is that no consideration is given to strain compatibility. In this study, a limit equilibrium based method where strain compatibility is maintained on the failure surface was developed. The method, referred to as the strain mobilisation method, considers a Mohr circle of stress at failure to determine the shear strength mobilised on the failure plane for use in the stability analysis as a function of the deviator stress imposed on the triaxial test result. The mobilisation of stress on a failure plane with strain was determined based on the stress-strain relationships observed during triaxial tests. A Factor of Safety (FoS) was used to express the stability of the slope as a function of the mobilised strain and the calculated FoS results obtained using the proposed method were compared to calculated FoS results using traditional methods. This was done for three tailings materials (gold, iron and platinum) for three specific hypothetical slopes. As an additional check, the proposed method was tested on Nerlerk sand, a well-known sand showing strain-softening behaviour during undrained shearing. It was found that, in general, as mobilised strain is increased, the FoS calculated using the proposed method converges to that of traditional methods so that there was no significant difference in calculated FoS between the current methods and the proposed method that does consider strain compatibility. This indicates that the proposed method provides FoS values comparable to those calculated using currently accepted methods where the failure surface passes predominantly through a single material type. For such a case, there does not appear to be a need to consider limit equilibrium methods where strain compatibility is maintained. The proposed method provides an indication of the amount of strain that may be expected to mobilise to provide the FoS. Given that this amount of strain is not excessive, the current methods which do not consider strain compatibility perform satisfactorily and can continue to be used / Dissertation (MEng (Civil Engineering))--University of Pretoria, 2021. / Civil Engineering / MEng (Civil Engineering) / Unrestricted

<div>This research consists of the development of a new educational tool for calculations of 2D slope stability problems, named PNW-SLOPE. Slope stability has been considered one of the most important topics in geotechnical engineering for many years, so this is a subject which students should build a good background in the university. This program was created in Microsoft Excel with the aid of VBA (Visual Basic for Applications). The use of VBA allowed the creation of a good user interface, therefore those who are using the program can easily follow the instructions to create, analyze the model and check the results. Even though there are many commercial programs with the same application, this research presents a new alternative, more focused on educational purposes. PNW-SLOPE is divided in several modules.The first consists of the geometry definition of the slope. The second module consists of a deterministic slope stability analysis considering limit equilibrium method and the method of slices. The third module consists of a probability analysis considering Monte Carlo simulation. With these two options, users can compare both analysis and understand how important is the consideration of probability analysis in Geotechnical Engineering. This is a pertinent topic nowadays, since reliability analysis is increasingly being incorporated in standards and design codes throughout the world. An additional module was created for rock slope stability problems in which the failure results from sliding on a single planar surface dipping into the excavation. Several examples are presented to demonstrate some of the features of PNW-SLOPE and results are verified with commercial programs such as Geostudio Slope/w and Rocscience Slide 2018.</div>

La presente tesis de investigación fue elaborada con la finalidad de contribuir con el estudio de la construcción de rampas de acceso a excavaciones mediante el análisis de los taludes provisionales sin sostenimiento que garanticen la estabilidad global en el Conglomerado de Lima. Las rampas de acceso son estructuras provisionales cuya construcción no se rige bajo normativas o indicaciones establecidas, además no contempla un estudio, se basa en la experiencia del responsable en obra. La ciudad de Lima se emplaza sobre un suelo gravoso el cual contribuye a que sea posible optimizar el grado de inclinación de los taludes provisionales. El alcance de este trabajo consiste en modelar una rampa de acceso en el conglomerado típico de Lima aplicando las sobrecargas existentes de la maquinaria y realizar un análisis de estabilidad global frente a condiciones estáticas y pseudodinámicas. Mediante la técnica de retroanálisis basándose en el método de Equilibrio Límite en Slide se estimarán los parámetros de resistencia mínimos característicos de la grava de Lima, el parámetro de cohesión y ángulo de fricción. A partir de ello se procederá a la optimización de los taludes, evaluando los diferentes grados de inclinación, y se estimarán las deformaciones producidas en los taludes a través del programa Plaxis, basado en Elementos Finitos. Finalmente se exponen las conclusiones obtenidas de la presente tesis de investigación, además de brindar recomendaciones para futuras investigaciones relacionadas a este tema. / This research thesis was developed with the purpose of contributing to the study of the construction of access ramps to building’s excavations by unsupported provisional slopes analysis to guarantee the global stability factor in the Lima Conglomerate. The access ramps are provisional structures whose construction is not governed by norms or established indications, in addition it does not include a study, it is based on the experience of the person responsible for the work. The city of Lima is located on a gravelly ground which helps to optimize the degree of inclination of the provisional slopes. The scope of this work is to model an access ramp in the typical conglomerate of Lima applying the existing machinery overloads and perform an analysis of global stability against static and pseudodynamic conditions. The minimum resistance parameters characteristic of the Lima gravel, the cohesion parameter and friction angle will be estimated using the retro-analysis technique based on the Limit Equilibrium method in Slide. From this, the slopes will be optimized, evaluating the different degrees of inclination, and the deformations produced in the slopes will be estimated through the Plaxis program, based on Finite Elements. Finally, the conclusions obtained from this research thesis are presented, as well as providing recommendations for future research related to this topic. / Tesis

No description available.

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.

Thesis regarding the application of the Kinematic Element Method to slope stability analysis in geotechnical engineering. / In this thesis, the effectiveness of the Kinematic Element Method (KEM), developed by Dr. Gussmann at the University of Stuttgart, was evaluated by comparing the solutions with the Limit Equilibrium Method (LEM), specifically the Morgenstern-Price method. The KEM was evaluated using a variety of problems, ranging from homogeneous slopes to retaining walls. The KEM was shown to predict similar potential failure mechanisms and values for the factor of safety (FS) as the Morgenstern-Price method. The FS were generally within the ±6% which is the range of variance for rigorous limit equilibrium methods. A simplified version of KEM (KEMv) was developed based on limit equilibrium formulations. In KEMv, an alternate iterative scheme to determine the FS is proposed, in which boundaries between elements are vertical. The KEMv provided similar values for the factor of safety and interelement forces as Gussmann’s KEM for vertical interelement boundaries given similar element locations. The KEM was assumed by Gussmann to be an upper bound solution. However, given the similarities in the solutions between KEM and KEMv, it may be a limit equilibrium method. The interelement forces from the KEM and KEMv were found to be sensitive to the location of the elements. Elements in the upper part of the slope often had small normal forces relative to shear forces, possibly being negative as well. Sensitivity analysis regarding the number of elements showed that a 5-element solution predicts the appropriate failure mechanism and provides a reasonably accurate FS. In a parametric study, slope geometry and soil properties were varied and comparisons were made between KEM and the Morgenstern-Price method. The KEMv displayed similar trends in factor of safety as the Morgenstern-Price method but predicted slightly larger values. The change in KEM critical slip surfaces with soil properties was consistent with trends predicted by Janbu’s dimensionless parameter. / Thesis / Master of Applied Science (MASc) / The stability of slopes is a challenging subject in geotechnical engineering. Geotechnical engineers are often interested in the factor of safety (FS), which is a quantitative measure of the stability of a slope. In this thesis, the effectiveness of the Kinematic Element Method (KEM) is evaluated by comparing its solutions to the Limit Equilibrium Method (LEM). The KEM was shown to predict similar potential failure mechanisms and values for the factor of safety. A simplified version of the KEM (KEMv) was developed based on LEM formulations. In KEMv, an alternate iterative scheme to determine the FS is proposed, in which the boundaries between elements are vertical. The KEMv provided similar values for the factor of safety and element forces as Gussmann’s KEM for vertical interelement boundaries. In a parametric study, KEM displayed similar trends in the change in FS and critical slip surface as the LEM.

A Costa Peruana apresenta alta atividade sísmica, tornando imprescindível a execução de análises de estabilidade que considerem os eventos sísmicos. Com o desenvolvimento de novas ferramentas numéricas, a análise dinâmica está se tornando cada vez mais importante e usual na fase de projeto, não se justificando mais a execução de análises estáticas em locais tão vulneráveis a sismos. A presente dissertação tem como objetivo realizar a análise da estabilidade dos Penhascos de Lima, Peru, considerando quatro taludes distintos, em uma região bastante afetada por abalos sísmicos. As análises foram executadas pelos métodos de equilíbrio limite, elementos finitos e pseudo-estático, buscando-se uma comparação entre os diferentes métodos. O trabalho apresenta uma descrição completa dos taludes em estudo, uma avaliação da condição sismológica da região e finalmente a estabilidade dos Penhascos de Lima, fazendo uso dos programas computacionais Slide (método do equilíbrio limite) e Plaxis (método dos elementos finitos) em 2D. Os resultados mostraram que os três métodos adotados forneceram fatores de segurança compatíveis, principalmente quando se considera perfis menos estratificados. Para perfis homogêneos, as diferenças obtidas foram da ordem de 0,5 a 1,0 %. As análises ressaltaram a importância de considerar a condição dinâmica, e mostraram-se bastante sensíveis aos valores de carga sísmica adotado. / The Peruvian coast has high seismic activity, making essential the implementation of stability analyzes that consider the seismic events. With the development of new numerical tools, dynamic analysis is becoming increasingly important and usual in the design phase is not justified over the execution of static analysis in places as vulnerable to earthquakes. This thesis aims to conduct the analysis of the stability of the cliffs of Lima, Peru, considering for different slopes, in a region highly affected by earthquakes. The analyzes were performed by equilibrium methods limit finite elements and pseudo-static, seeking a comparison between the different methods. The dissertation presents a complete description of the slopes in the study, an evaluation of the seismic condition of the region and finally the stability of Lima cliffs, making use of computer programs Slide (limit equilibrium method) and Plaxis (finite element method). The results showed that all three methods provided adopted gave safety factors, especially when considering less laminated profiles. For homogeneous profiles, obtained differences were of the order of 1.0 at 0.5%. The analysis highlighted the importance of considering the dynamic condition, and were quite sensitive to seismic load values adopted.