大型反倾库岸岩体变形过程及破坏机制数值模拟

NUMERICAL SIMULATION OF DEFORMATION PROCESS AND FAILURE MECHANISM OF RESERVOIR BANK SLOPE WITH LARGE-SCALE ANTI-DIP ROCK MASS

随着边坡地质结构、地层岩性和诱发因素的不同,反倾岩体的主控变形破坏模式都会发生改变。金沙江龙蟠边坡岩体主要为反倾向千板岩和砂岩互层状结构,坡脚河床深厚覆盖层构成了边坡的软弱支座。本文运用离散单元法模拟了大型反倾库岸岩体在漫长的地质历史时期中的变形演化过程,并基于反倾岩体变形的时效性观点,引入强度折减法分析边坡在不同阶段的剪切屈服区扩展情况及相应的稳定性状态。结论表明龙蟠边坡变形岩体是重力弯曲蠕变为主导的成因机制,并归纳提出了软基效应和互层效应共同作用下的大规模反倾岩体的累进性剪切破坏模式,俗称"龙蟠模式"。

The primary deformation and failure mechanism of reservoir bank slopes with anti - dip rock mass are dominated by the geological structure, stratum lithology and inducing loading factors. The Longpan slope is located at the right embankment of Dale dam on Jinsha River. It consists of anti - dip alternate sandstone and slate strata. The thick riverbed sediments form a soft basement of the slope. This paper takes the Longpan slope as a case study and uses the discrete element method to simulate the deformation evolution process of the slope rock mass. Based on the viewpoint of time - dependent deformation, the strength reduction method is introduced to evaluate the factor of safety of the anti - dip rock slope. The numerical modeling result verifies that the geological mechanism is actually a deep - seated gravitational bending deformation. In accordance with the expansion way of the shear yielding zones ~ the progressive shear failure mechanism of the large - scale anti - dip rock masses with effects of interbedded strata and soft foundation is proposed in the paper. This mechanism is believed to have significance in the slope failure prevention.