COMPUTER AIDED ANALYSIS OF STABILITY OF SOIL AND RESERVOIR SLOPES

Abstract

Man made and natural slopes such as those of dams, embankments and reservoir slopes need to be examined for adequate factor of safety. The stability analysis of slopes involves laborious computations as a number of trial slip circles are to be analysed. A computer program makes the job easier and quicker. Singh and Ramasamy (1979) developed computer programs for stability analysis and back analysis of natural slopes using Bishop's simplified method of analysis. The program was well suited for the analysis of slopes having irregular ground profile, which is a common feature in the case of natural slopes. This program is modified to account for pore water pressure, depth of tension crack, depth of water in tension crack and reservoir water level. Some more programs to account for the features which make the programs applicable for a wide range of real situations have also been developed. The programs developed are listed below.: (i) Stability analysis of reservoir slopes with circular wedge mode of failure [SARC]. (ii) Back analysis of slopes with circular wedge mode of failure [BASC]. (iii) Stability analysis of slopes of talus deposit [SASTI. This program also provides for the design of remedial measures in the form of drains or excavations, if required. -2- (iv) Back analysis of slopes of talus deposit [BAST]. (v) In the excavation problems, it is required to know the. steepest stable slope, providing a given factor of safety. To solve this type of problems, a program [PIT] is developed. (vi) Sliding of a resevoir• slope generates high water waves. To calculate the height of water'waves a simple program has been developed [WAVE]. To illustrate the use of the programs developed some typical natural slopes have been analysed. Further, some numerical problems have also been solved to bring out the following (a) Height of wave generated in a reservoir due to land slide, (a) Effect of earthquake force on factor of safety, (b) Effect of pore water pressure on factor of safety, (c) Effect of reservoir water level fluctuation on factor of safety, (d) Effect of surcharge on factor of safety, Based on the above results it has been shown that the programs can handle a variety of real situations where stability of slopes is required to be analysed. slopes of Koteshwar dam reservoir rim have been analysed using .SARC and BASC programs.