Geotechnical engineering design has relied upon deterministic methods of analysis whereby values for analysis parameters and conditions are selected subjectively based on judgment with the intent of providing acceptable margins of safety. The objective of this research was to improve the use of probabilistic slope stability analysis in practice so that the design of slopes can be made on a consistent and probabilistic basis. The current research involved the development of a methodology for the measurement and modeling of the anisotropic autocorrelation distance of cohesive soils, which was demonstrated at Dyke 17 West of the McArthur Falls Generating Station. In-situ testing using the piezocone and laboratory testing was conducted to characterize the spatial variability of the effective-shear strength envelope. Vertical (down-hole) and horizontal (cross-hole) geostatistical analysis was conducted to assess the anisotropy of the semivariogram. The investigation identified that heterogeneous inclusions had significant impacts on the results, but that simplistic (visual) identification and filtering procedures were adequate. The effective-stress shear strength envelope was statistically characterized as a random field, which was simulated as a first-order Markov process using customized add-in functions in a limit-equilibrium slope stability analysis. The analysis accounts for the spatial variability of shear strength and is capable of simulating both isotropic and anisotropic autocorrelation functions. The study showed that the critical slip surface geometry and the probability of failure can be significantly different when the anisotropy of spatial correlation is accounted for. The study also showed that neglecting spatial correlation may over-estimate the probability of failure, however this finding was noted to be likely case-specific. The primary conclusion of the study was that appropriate representation of spatial correlation is essential to calculating the probability of failure. Finally, convergence of the probabilistic simulation was evaluated using bootstrapping of the simulated factor of safety distribution to assess the standard error in the mean factor of safety, standard deviation of factor of safety and the probability of failure. A convergence criterion based on the percentage standard error in the probability of failure was proposed and used to define the number of Monte-Carlo iterations required.

Submitted by Rafael Muraro Derrite null (rmderrite@yahoo.com.br) on 2017-06-08T11:36:06Z No. of bitstreams: 1 RMDerrite-Dissertação.pdf: 10693361 bytes, checksum: b698bdf7fcbbdb400564bd3ad2ffe787 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-06-08T16:41:45Z (GMT) No. of bitstreams: 1 derrite_rm_me_bauru.pdf: 10693361 bytes, checksum: b698bdf7fcbbdb400564bd3ad2ffe787 (MD5) / Made available in DSpace on 2017-06-08T16:41:45Z (GMT). No. of bitstreams: 1 derrite_rm_me_bauru.pdf: 10693361 bytes, checksum: b698bdf7fcbbdb400564bd3ad2ffe787 (MD5) Previous issue date: 2017-03-06 / A heterogeneidade hidrogeológica do meio físico é um dos fatores principais na definição da distribuição dos contaminantes e seus subprodutos para elaboração de um Modelo Conceitual da Área (MCA). Existem diversas abordagens para a investigação ambiental de áreas contaminadas, sendo que a investigação de alta resolução (High Resolution Site Characterization - HRSC) permite obter um detalhamento em densidade e escala adequadas, tanto da variabilidade vertical e horizontal da condutividade hidráulica e dos tipos de solo, quanto das concentrações dos contaminantes, sua distribuição e interações no meio físico. Uma das ferramentas de alta resolução utilizada para se definir o Modelo Conceitual do Meio Físico é o piezocone (CPTu), a qual permite avaliar e classificar o tipo de solo e descrever um perfil hidroestratigráfico em escala centimétrica. O presente estudo teve como principal objetivo definir perfis e seções hidroestratigráficas em alta resolução, utilizando amostragem de solo Direct Push Dual Tube Sampling (DPDTS) e ensaios CPTu com Dissipação de Poro-Pressão (PPDT). A amostragem de solo DPDTS permitiu uma caracterização do solo in situ, definindo-se preliminarmente as principais zonas de fluxo e armazenamento de eventual contaminação. Os ensaios CPTu detectaram o tipo de solo em microescala (centímetros), com a identificação adequada das zonas de fluxo e armazenamento, bem como estabeleceram um perfil contínuo de condutividade hidráulica, além também de fornecerem dados pontuais através dos ensaios PPDT, definindo-se, então, um perfil hidroestratigráfico em alta resolução, subsidiando o projeto e aplicação de qualquer técnica de remediação. Os resultados mostraram grandes diferenças entre as descrições do tipo de solo obtidas pela sondagem DPDTS (tátil-visual) e pelos ensaios CPTu. Estes últimos possibilitaram identificar a heterogeneidade do meio físico, sua variação e alternância da condutividade hidráulica em detalhe, tendo sido detectados até cinco tipos de solos distintos pelos ensaios CPTu dentro de um único descrito pelo método tátil-visual (DPDTS), demonstrando o potencial de emprego dessa técnica para definição da hidrogeologia em escala centimétrica e a vantagem da sua utilização como ferramenta de alta resolução. / The hydrogeological heterogeneity of the physical environment is one of the main factors in the definition of the distribution of contaminants and their by-products for the elaboration of a Conceptual Site Model (CSM). There are several approaches to the environmental investigation of contaminated sites, and the High-Resolution Site Characterization (HRSC) allows to obtain an adequate density and scaling detail of both vertical and horizontal variability of hydraulic conductivity and soil types, as well as the concentrations of contaminants, their distribution and interactions in the physical environment. One of the high-resolution tools used to define the Conceptual Model of the Physical Environment is the piezocone (CPTu), which allows to evaluate and classify the soil type and describe a hydrostratigraphic profile in a centimeter scale. The main purpose of the present study was to define high-resolution hydrostratigraphic profiles and sections using Direct Push Dual Tube Sampling (DPDTS) and CPTu tests with Pore-Pressure Dissipation (PPDT). The DPDTS soil sampling allowed an in-situ soil characterization, defining the main flux and storage zones of eventual contaminants. The CPTu tests detected the soil type in microscale (centimeters), with adequate identification of the flux and storage zones, also established a continuous profile of hydraulic conductivity, as well as obtained punctual data through the PPDT tests, thus defining the hydrostratigraphic profile in high resolution, supporting the design and application of any remediation technique. The results showed large differences between the soil type descriptions obtained by the DPDTS (tactile-visual) and the CPTu tests. The latter allowed the identification of the heterogeneity of the physical environment, its variation and alternation of hydraulic conductivity in detail, and up to five different soil types were detected by the CPTu tests within a single type described by the tactile-visual method (DPDTS), demonstrating the potential use of this technique to define the local hydrogeology in a centimeter scale and the advantage of its use as a high-resolution tool.

O principal objetivo deste trabalho foi estudar a aplicabilidade da tecnologia do piezocone na investigação geoambiental de solos tropicais a partir da realização de ensaios nas áreas onde se encontram o aterro de resíduos sólidos urbanos de Bauru e o antigo lixão de Ribeirão Preto, ambos no Estado de São Paulo. Dentro deste contexto, outros ensaios de campo e de laboratório foram analisados para um melhor entendimento do caminhamento da pluma de contaminação e dos próprios resultados dos ensaios com piezocone realizados nestas áreas de disposição de resíduos. A tecnologia do piezocone apresentou limitações quando empregada na área do antigo lixão de Ribeirão Preto, uma vez que o impenetrável do cone foi atingido antes do nível d’água, impossibilitando assim a identificação da posição deste, a estimativa da permeabilidade do solo e a coleta de amostras de água. Os ensaios de eletrorresistividade de superfície permitiram a detecção do formato e do sentido do caminhamento da pluma de contaminação e foram fundamentais para a orientação dos locais onde foram realizados os ensaios de piezocone e amostragem de solo e água nas duas áreas estudadas. Os resultados dos ensaios com o piezocone de resistividade (RCPTU) realizados no aterro de resíduos sólidos urbanos de Bauru mostraram que os valores de resistividade são fortemente afetados pelo grau de saturação, gênese, textura e tipo de argilo-mineral presente na fração fina do solo. Constatou-se que o ensaio RCPTU possibilitou identificar zonas com presença de poluentes, as quais foram confirmadas a partir da análise conjunta dos resultados dos ensaios de geofísica de superfície e das amostras de solo e água coletadas com os amostradores do sistema direct-push e dos poços de monitoramento. Este trabalho apresenta ainda resultados preliminares de ensaios de laboratório, que foram úteis para avaliar a capacidade de retenção do solo que ocorre no entorno do aterro de resíduos sólidos urbanos de Bauru para os metais Ni, Zn, Cd e Pb. Os resultados dos ensaios de adsorção em lote e de coluna indicam que a poluição no entorno deste aterro pode estar ocorrendo de forma lenta, destacando-se a importância da continuidade do monitoramento do aqüífero local. / The major purpose of this dissertation is to study the applicability of the piezocone technology for geoenvironmental site investigation of tropical soils. Two waste disposal sites were investigated: a deactivated dumpsite in Ribeirão Preto and a sanitary landfill in Bauru, in São Paulo State, Brazil. Other in situ and laboratory tests were carried out in these two areas for a better understanding of the leacheate plume and of the results gathered with piezocone tests. The piezocone technology presented limitations to investigate Ribeirão Preto site, since groundwater level is deeper than the impenetrable to the cone. For reason, it was impossible to estimate permeability and no water samples using the direct-push technology were obtained. Geophysical tests carried out at the two studied sites allowed to detect and delineate the shape of leachate plume. They were fundamental to guide and locate the piezocone tests, soil and water sampling and monitoring wells. The resistivity piezocone tests (RCPTU) carried out in Bauru site showed that the resistivity values are very affected by degree of saturation, genesis, fabric and clay mineral type. Geophysical tests results, soil and water samples collected by direct-push technology and by monitoring wells supported the interpretation of RCPTU tests. These tests were able to identify polluted zones. Preliminary laboratory tests were carried out to access retention of Ni, Zn, Cd and Pb by the soil from Bauru site. The results of leaching and batch equilibrium tests indicated that pollution around this site is taking place slowly, emphasizing the importance to continue monitoring groundwater.

Site characterization is an important task in Geotechnical Engineering. In situ tests based on standard penetration test (SPT), cone penetration test (CPT) and shear wave velocity survey are popular among geotechnical engineers. Site characterization using any of these properties based on finite number of in-situ test data is an imperative task in probabilistic site characterization. These methods have been used to design future soil sampling programs for the site and to specify the soil stratification. It is never possible to know the geotechnical properties at every location beneath an actual site because, in order to do so, one would need to sample and/or test the entire subsurface profile. Therefore, the main objective of site characterization models is to predict the subsurface soil properties with minimum in-situ test data. The prediction of soil property is a difficult task due to the uncertainities. Spatial variability, measurement ‘noise’, measurement and model bias, and statistical error due to limited measurements are the sources of uncertainities. Liquefaction in soil is one of the other major problems in geotechnical earthquake engineering. It is defined as the transformation of a granular material from a solid to a liquefied state as a consequence of increased pore-water pressure and reduced effective stress. The generation of excess pore pressure under undrained loading conditions is a hallmark of all liquefaction phenomena. This phenomena was brought to the attention of engineers more so after Niigata(1964) and Alaska(1964) earthquakes. Liquefaction will cause building settlement or tipping, sand boils, ground cracks, landslides, dam instability, highway embankment failures, or other hazards. Such damages are generally of great concern to public safety and are of economic significance. Site-spefific evaluation of liquefaction susceptibility of sandy and silty soils is a first step in liquefaction hazard assessment. Many methods (intelligent models and simple methods as suggested by Seed and Idriss, 1971) have been suggested to evaluate liquefaction susceptibility based on the large data from the sites where soil has been liquefied / not liquefied. The rapid advance in information processing systems in recent decades directed engineering research towards the development of intelligent models that can model natural phenomena automatically. In intelligent model, a process of training is used to build up a model of the particular system, from which it is hoped to deduce responses of the system for situations that have yet to be observed. Intelligent models learn the input output relationship from the data itself. The quantity and quality of the data govern the performance of intelligent model. The objective of this study is to develop intelligent models [geostatistic, artificial neural network(ANN) and support vector machine(SVM)] to estimate corrected standard penetration test (SPT) value, Nc, in the three dimensional (3D) subsurface of Bangalore. The database consists of 766 boreholes spread over a 220 sq km area, with several SPT N values (uncorrected blow counts) in each of them. There are total 3015 N values in the 3D subsurface of Bangalore. To get the corrected blow counts, Nc, various corrections such as for overburden stress, size of borehole, type of sampler, hammer energy and length of connecting rod have been applied on the raw N values. Using a large database of Nc values in the 3D subsurface of Bangalore, three geostatistical models (simple kriging, ordinary kriging and disjunctive kriging) have been developed. Simple and ordinary kriging produces linear estimator whereas, disjunctive kriging produces nonlinear estimator. The knowledge of the semivariogram of the Nc data is used in the kriging theory to estimate the values at points in the subsurface of Bangalore where field measurements are not available. The capability of disjunctive kriging to be a nonlinear estimator and an estimator of the conditional probability is explored. A cross validation (Q1 and Q2) analysis is also done for the developed simple, ordinary and disjunctive kriging model. The result indicates that the performance of the disjunctive kriging model is better than simple as well as ordinary kriging model. This study also describes two ANN modelling techniques applied to predict Nc data at any point in the 3D subsurface of Bangalore. The first technique uses four layered feed-forward backpropagation (BP) model to approximate the function, Nc=f(x, y, z) where x, y, z are the coordinates of the 3D subsurface of Bangalore. The second technique uses generalized regression neural network (GRNN) that is trained with suitable spread(s) to approximate the function, Nc=f(x, y, z). In this BP model, the transfer function used in first and second hidden layer is tansig and logsig respectively. The logsig transfer function is used in the output layer. The maximum epoch has been set to 30000. A Levenberg-Marquardt algorithm has been used for BP model. The performance of the models obtained using both techniques is assessed in terms of prediction accuracy. BP ANN model outperforms GRNN model and all kriging models. SVM model, which is firmly based on the theory of statistical learning theory, uses regression technique by introducing -insensitive loss function has been also adopted to predict Nc data at any point in 3D subsurface of Bangalore. The SVM implements the structural risk minimization principle (SRMP), which has been shown to be superior to the more traditional empirical risk minimization principle (ERMP) employed by many of the other modelling techniques. The present study also highlights the capability of SVM over the developed geostatistic models (simple kriging, ordinary kriging and disjunctive kriging) and ANN models. Further in this thesis, Liquefaction susceptibility is evaluated from SPT, CPT and Vs data using BP-ANN and SVM. Intelligent models (based on ANN and SVM) are developed for prediction of liquefaction susceptibility using SPT data from the 1999 Chi-Chi earthquake, Taiwan. Two models (MODEL I and MODEL II) are developed. The SPT data from the work of Hwang and Yang (2001) has been used for this purpose. In MODEL I, cyclic stress ratio (CSR) and corrected SPT values (N1)60 have been used for prediction of liquefaction susceptibility. In MODEL II, only peak ground acceleration (PGA) and (N1)60 have been used for prediction of liquefaction susceptibility. Further, the generalization capability of the MODEL II has been examined using different case histories available globally (global SPT data) from the work of Goh (1994). This study also examines the capabilities of ANN and SVM to predict the liquefaction susceptibility of soils from CPT data obtained from the 1999 Chi-Chi earthquake, Taiwan. For determination of liquefaction susceptibility, both ANN and SVM use the classification technique. The CPT data has been taken from the work of Ku et al.(2004). In MODEL I, cone tip resistance (qc) and CSR values have been used for prediction of liquefaction susceptibility (using both ANN and SVM). In MODEL II, only PGA and qc have been used for prediction of liquefaction susceptibility. Further, developed MODEL II has been also applied to different case histories available globally (global CPT data) from the work of Goh (1996). Intelligent models (ANN and SVM) have been also adopted for liquefaction susceptibility prediction based on shear wave velocity (Vs). The Vs data has been collected from the work of Andrus and Stokoe (1997). The same procedures (as in SPT and CPT) have been applied for Vs also. SVM outperforms ANN model for all three models based on SPT, CPT and Vs data. CPT method gives better result than SPT and Vs for both ANN and SVM models. For CPT and SPT, two input parameters {PGA and qc or (N1)60} are sufficient input parameters to determine the liquefaction susceptibility using SVM model. In this study, an attempt has also been made to evaluate geotechnical site characterization by carrying out in situ tests using different in situ techniques such as CPT, SPT and multi channel analysis of surface wave (MASW) techniques. For this purpose a typical site was selected wherein a man made homogeneous embankment and as well natural ground has been met. For this typical site, in situ tests (SPT, CPT and MASW) have been carried out in different ground conditions and the obtained test results are compared. Three CPT continuous test profiles, fifty-four SPT tests and nine MASW test profiles with depth have been carried out for the selected site covering both homogeneous embankment and natural ground. Relationships have been developed between Vs, (N1)60 and qc values for this specific site. From the limited test results, it was found that there is a good correlation between qc and Vs. Liquefaction susceptibility is evaluated using the in situ test data from (N1)60, qc and Vs using ANN and SVM models. It has been shown to compare well with “Idriss and Boulanger, 2004” approach based on SPT test data. SVM model has been also adopted to determine over consolidation ratio (OCR) based on piezocone data. Sensitivity analysis has been performed to investigate the relative importance of each of the input parameters. SVM model outperforms all the available methods for OCR prediction.

O principal objetivo deste trabalho foi estudar a aplicabilidade da tecnologia do piezocone na investigação geoambiental de solos tropicais a partir da realização de ensaios nas áreas onde se encontram o aterro de resíduos sólidos urbanos de Bauru e o antigo lixão de Ribeirão Preto, ambos no Estado de São Paulo. Dentro deste contexto, outros ensaios de campo e de laboratório foram analisados para um melhor entendimento do caminhamento da pluma de contaminação e dos próprios resultados dos ensaios com piezocone realizados nestas áreas de disposição de resíduos. A tecnologia do piezocone apresentou limitações quando empregada na área do antigo lixão de Ribeirão Preto, uma vez que o impenetrável do cone foi atingido antes do nível d’água, impossibilitando assim a identificação da posição deste, a estimativa da permeabilidade do solo e a coleta de amostras de água. Os ensaios de eletrorresistividade de superfície permitiram a detecção do formato e do sentido do caminhamento da pluma de contaminação e foram fundamentais para a orientação dos locais onde foram realizados os ensaios de piezocone e amostragem de solo e água nas duas áreas estudadas. Os resultados dos ensaios com o piezocone de resistividade (RCPTU) realizados no aterro de resíduos sólidos urbanos de Bauru mostraram que os valores de resistividade são fortemente afetados pelo grau de saturação, gênese, textura e tipo de argilo-mineral presente na fração fina do solo. Constatou-se que o ensaio RCPTU possibilitou identificar zonas com presença de poluentes, as quais foram confirmadas a partir da análise conjunta dos resultados dos ensaios de geofísica de superfície e das amostras de solo e água coletadas com os amostradores do sistema direct-push e dos poços de monitoramento. Este trabalho apresenta ainda resultados preliminares de ensaios de laboratório, que foram úteis para avaliar a capacidade de retenção do solo que ocorre no entorno do aterro de resíduos sólidos urbanos de Bauru para os metais Ni, Zn, Cd e Pb. Os resultados dos ensaios de adsorção em lote e de coluna indicam que a poluição no entorno deste aterro pode estar ocorrendo de forma lenta, destacando-se a importância da continuidade do monitoramento do aqüífero local. / The major purpose of this dissertation is to study the applicability of the piezocone technology for geoenvironmental site investigation of tropical soils. Two waste disposal sites were investigated: a deactivated dumpsite in Ribeirão Preto and a sanitary landfill in Bauru, in São Paulo State, Brazil. Other in situ and laboratory tests were carried out in these two areas for a better understanding of the leacheate plume and of the results gathered with piezocone tests. The piezocone technology presented limitations to investigate Ribeirão Preto site, since groundwater level is deeper than the impenetrable to the cone. For reason, it was impossible to estimate permeability and no water samples using the direct-push technology were obtained. Geophysical tests carried out at the two studied sites allowed to detect and delineate the shape of leachate plume. They were fundamental to guide and locate the piezocone tests, soil and water sampling and monitoring wells. The resistivity piezocone tests (RCPTU) carried out in Bauru site showed that the resistivity values are very affected by degree of saturation, genesis, fabric and clay mineral type. Geophysical tests results, soil and water samples collected by direct-push technology and by monitoring wells supported the interpretation of RCPTU tests. These tests were able to identify polluted zones. Preliminary laboratory tests were carried out to access retention of Ni, Zn, Cd and Pb by the soil from Bauru site. The results of leaching and batch equilibrium tests indicated that pollution around this site is taking place slowly, emphasizing the importance to continue monitoring groundwater.