基于双折减系数法的岩质边坡平面滑动分析

Planar Failure Surface Analysis of Rock Slope Based on Dual Reduction Factor Method

离散元强度折减法是在众多的结构面组合中通过不断地等比例折减结构面强度参数c、tanф来寻找最先造成边坡失稳的滑动面。事实上,边坡在渐进破坏的过程中,无论是岩体或是结构面的强度参数并不是同等程度地衰减,如何选择合适的衰减路径是强度折减法首要考虑的问题。基于以上认识,首先建立不同几何构型的岩质边坡模型,分析单平面滑动和双平面滑动两种情况下的结构面c-tanф曲线变化规律,发现其中仅有在双平面滑动破坏模式下不同的临界状态点会对应不同的临界滑动面,然后通过算例以η=R_1/R_2(R_1为单独折减c所得,R_2为单独折减tanф所得)作为配套折减比例,寻求边坡双平面滑动临界失稳状态,比较两种折减方法的差异,发现双强度折减法得出的滑动面范围更小,传统强度折减法偏向保守。

The discrete element strength reduction method is to find the sliding surface whichfirstly causes the instability of the slope from many combinations of strutural planes by reducing the shear strength parameters c and tanΦin equal proportion.In fact,in the process of gradual destruction,the shear strength parameters of rock and structural plane have different decay rates,so the first question is to find appropriate decay path.Based on the above understanding,different rock slope shapes are firstly established to analyze the c-tanΦcritical state curve of structural plane under the situation of single plane sliding and double plane sliding,it is found that different critical state points correspond to different critical sliding planes only in the double plane sliding failure mode;thenη=R 1/R 2(R 1 and R 2 are determined by single reduction of c and tanΦ)is regarded as the matching reducing ratio to find critical instability state of the double plane slidingthrough one example;finally the difference between these two reduction methods is analyzed.The result shows that the range of sliding planecalculated by double reduction method is smaller and the traditional reduction method is partial to conservatism.