裂隙渗流对岩石边坡稳定的影响——渗流、变形耦合作用的DDA法

INFLUENCE OF SEEPAGE ON THE STABILITY OF ROCK SLOPE——COUPLING OF SEEPAGE AND DEFORMATION BY DDA METHOD

裂隙中的渗流是岩石边坡失稳的重要因素之一。在最近发展起来的离散型数值方法——DDA法的基础上,考虑裂隙网络中地下水的流动,以及渗流压力与岩石变形的耦合作用,从能量最小原理出发,推求了考虑裂隙渗流情况下岩石系统的瞬时平衡方程及对任意裂隙进行安全评价的局部安全系数。用该方法对日本某隧道的塌方事故进行了模拟分析,数值模拟再现了该隧道破坏的过程。模拟结果表明,由于连续降雨和表面结冰导致岩石裂隙中地下水位升高,过大的水压力致使隧道上部的垂向裂隙张开并向下扩展,最终导致整个岩坡的崩塌。研究结论与日本事故委员会的调查结果一致。

Seepage is an important factor in the failure of rock slope. The extended discontinuous deformation analysis (DDA) method is presented by considering the seepage in fracture network and the coupling of seepage and deformation of rock. The local safety factor along the given path can be calculated. By the extended DDA method, the failure process of a tunnel in Japan is simulated. It is shown that the direct reason of the failure is raining and icing, which raises the level of underground water and causes the propagation of fracture. The result agrees with the investigating conclusion by Accident Investigation Committee of Japan.