ABSTRACT:

The study of the slope stability of surface structures such as a surface hydropower plant is an important task which should be considered by rock mechanics experts. This paper deals with the large-scale slope stability of hydropower plant of Khersan III dam in Iran. Existence of some factors such as sharp scarp on the top of this slope emphasizes the importance of this study. In this paper, firstly, the stability of this slope is analyzed using numerical modeling and secondly the rock fall analysis is presented.

1. INTRODUCTION

The rock slope stability analysis has been extensively studied in the last few decades. Various methods such as the Limit Equilibrium and Numerical methods have been developed for the stability analysis of the slopes. One of the most serious problems in the slopes is the accidental fall of rock blocks that are formed by discontinuities in the rock mass. Prediction and prevention of rock fall requires the evaluation of the rock blocks stability based on a precise characterization of discontinuities in the rock mass. The hydropower plant of Khersan III dam is a surface structure which is located at the right bank of this dam. As it can be seen from Figure 1 and 2, there is a sharp scarp above the hydropower plant which can cause serious problems not only for the stability of the hydropower plant trench but also for the safety of the personnel during the operation period of the hydropower plant. The main concern in this regard is related to the rock fall in this slope. Up to now, different protection systems have been designed against rock fall, the most common being rock restraining nets, catch walls or deformable barriers. The system shall be designed to withstand dynamic forces generated from rocks impacting the installed system. In this paper, the stability of the slope located adjacent to the hydropower plant is discussed and the results of rock fall analysis is presented.

2. NUMERICAL ANALYSIS OF THE SLOPE LOCATED ADJACENT TO THE HYDROPOWER PLANT OF KHERSAN-III DAM

The hydropower plant of Khersan III dam is a surface construction. Considering this matter and the sharp scarp which exist on the top of the hydropower plant area, a detail investigation on the stability of this slope is necessity. The numerical modeling of this slope is described in the following parts.

2.1. Selection Of Modeling Method

In case that rock mass is free of joint or the dimensions of the blocks formed as a result of the surrounding joint sets are very smaller than the dimensions of the structure or the under consideration area, the rock mass may behave as a continuum media [1,2]. Based on the geological and rock mechanics studies carried out in this project, the dimensions of slope in vicinity of hydropower plant, joints spacing which is variable between 20 cm to 2 m, and existing three joint sets, the continuum model was used to investigate on the stability of this slope.

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