百色水利枢纽主坝坝基三维抗滑稳定分析

THREE-DIMESIONAL STABILITY ANALYSIS OF DAM FOUNDATION OF BAISE HYDRO-JUNCTION

百色水利枢纽位于广西百色市郁江上游的右江河段,其溢流坝段深层抗滑稳定问题受到高度关注。由于溢流坝段不同断面的二维安全系数相差较大,很难确定整个坝段的抗滑稳定安全系数,采用基于上限定理的三维极限分析方法来分析这一问题。计算中采用的岩体参数通过地质力学试验以及节理随机网络模拟确定,分析了两种最可能的滑动模式。结果表明,在考虑三维效应之后,溢流坝段可以认为是安全的。然而,为进一步确保坝基的安全,需要在溢流坝段坝踵位置建造一个5m深的齿槽。

It＇s usually difficult to determine the actual safety factors of rock masses in ordinary 2D stability analysis if the safety factors of different cross sections in the rock mass vary significantly. Besides actual slope, arch dam abutment, and actual foundation of a high building, another example is that the different cross sections of the foundation in a monolith of a gravity dam vary significantly, just like the condition at the overflow dam in Baise Project. 3D stability analysis method based on the upper-bound theorem is employed to solve this problem. The parameters used in the analysis are obtained from the geomechanical tests as well as continuity simulations of the random distributed joints. Two failure patterns against sliding are analyzed. One pattern is that the foundation slides along deep seated planes which are determined by calculations. Another pattern is that the foundation slides along the planes across the bottom of the high steps in the foundation pit. The results indicate that a special overflow dam monolith can be considered to be safe in case considering three-dimensional effect. However, a key wall with a depth of 5 m must be constructed at the upper side of this monolith in order to ensure the safety of the foundation.