岩质边坡倾倒破坏的非连续变形分析

Discontinuous Deformation Analysis of Rock Slope Failure

岩质边坡倾倒破坏存在块体的滑移、转动,及块体本身的折断。常规的离散元、非连续变形分析方法(DDA)虽然擅长处理块体的滑移和转动,但不能模拟连续体本身的破坏。然而通过在DDA方法中引入虚拟节理和真实节理的概念(即DDARF方法),用真实节理表征岩体中已经存在的天然节理、层面等,用起粘结作用的虚拟节理表征连续体。该方法可模拟连续体的变形及连续体的破坏。为此,首先对DDARF方法中的虚拟节理模型进行了着重的介绍。然后利用DDARF方法对龙滩边坡倾倒破坏的离心模型试验进行研究。研究结果表明,反倾块体的下部几乎没有明显的位移,而位于破坏面以上的部分产生明显的倾倒位移,导致在反倾块体的中部发生弯折破坏,形成贯通整个坡体的破坏面。数值模拟结果与离心模拟试验结果吻合得很好,验证了DDARF方法的有效性。

Block sliding, rotation or broken exist during toppling failure of rock slope. Although sliding and rotation of block can be well dealt with by conventional discrete element method or DDA method, the damage of the continuum itseff cannot be simulated by those methods. Therefore, those methods are unable to simulate block fracture in the process of toppling failure. However, by introducing concepts of virtual joints and true joint in the DDA approach （ i.e. DDARF method）, the existing natural joints can be represented by real joint, where continuum can be characterized by cohesive effect of virtual joint. This method can not only simulate the deformation of continuum, but also simulate fracture of the continuum. In this paper, the virtual joint model in DDARF was introduced firstly. Then the toppling failure of centrifu- gal model test for Longtan slope was simulated using the method of DDARF. The results indicate that the displacement of the lower part of the block is not significant, while the displacement of the block located above the failure surface is obvi- ous, which lead to bending damage in the middle of the blocks, and a failure surface through entire slope is formed finally. The numerical simulation results agree very well with that of experimental centrifuge model test, which verifies the correctness of DDARF method.