Assessment of slope stability and stabilization techniques through probabilistic approach

Abstract

Uncertainty and randomness of data is a major Issue associated in geotechnical engineering. It is therefore desirable. to use methods and concepts in engineering planning and design that can facilitate the evaluation and analysis of uncertainty. Formal probabilistic approach provides a useful framework to incorporate these uncertainties in slope instability problems. Under the research described in this thesis, number of probabilistic models have been developed to evaluate the stability of slopes and their use in the evaluation of stability of slopes and the evaluation of effectiveness of various stabilization techniques have been discussed. Two probabilistic analytical models that can be used to evaluate the stability of slopes that can fail either along circular failure surfaces or non-circular failure surfaces have been developed. These models formally recognize the uncertainties associated with various geotechnical parameters and provide means to quantify their effects on the stability. The result is given in the form of probability of unsatisfactory performance of the slope. Each mode! developed was facilitated to perform computations in five different ways ranging from theoretically sound methods to some approximate methods, and the results obtained were compared with each other. In addition, the results were compared with the results obtained by a commercial software, wherever applicable. In addition, two other probabilistic analytical models were developed to analyze the slopes stabilized by soil nailing. It is seen that the behavior of the probabilistic models developed under this research perform satisfactorily, and it can be recommended to use these models in routine problems of slope instability to provide more realistic results incorporating the uncertainties associated with various geotechnical parameters. Analyses of a number of examples and case histories discuss the uses of the probability of failure in decision making to evaluate the stability of slopes as well as the effectiveness of various stabilization techniques. It also emphasizes the importance of the appropriate failure mechanism and the appropriate deterministic model in the probabilistic analysis. Analysis of case histories provides an important discussion showing the inadequacy of the conventional factor of safety alone in evaluating the stability of slopes.