降雨对滑坡稳定性影响过程分析

Effect of rainfall on the stability of landslides

通过对滑坡土条的受力分析进行改进,建立起能考虑滑带内存在任意孔隙水压分布情况下的稳定性计算公式。结合Lumb入渗理论和太沙基一维固结理论得到了滑坡在降雨期间的极限稳定性计算方法,该方法能够同时考虑降雨入渗导致土体重度和滑带内孔隙水压力变化。利用上述结果,提出了某些深层滑坡触发的一种机理,并可根据常用的土质参数比较容易得到滑坡在降雨期间稳定性演化过程。通过对某滑坡分析得到,降雨导致滑体重量增加而降低滑坡稳定性小于孔隙水压增加对稳定性的影响;超孔隙水压力的存在大幅提高了剩余下滑力值。

Formulations of stability calculation of landslides are presented by the improvement of the force analysis of soil slices with random distribution of pore water pressure in slip zone. A limit equilibrium method, which combines the Lumb＇ s infiltration theory and Terzaghi＇ s one dimensional consolidation theory, is achieved for stability evaluation of landslides during the period of rainfall. The effects of the changes of the unit weight and pore water pressure caused by rainfall are taken into account by this method. A kind of triggering mechanism of some deep landslides is brought forward and the change process of stability of landslides induced by rainfall is gotten easily from the normal soil parameters by this method. Two main results are gotten from a case study： the decrease of stability coming from the change of unit weight is lower than that from the variation of pore pressure; the increase of residual sliding force is prominent because of the occurrence of excess pore water pressure.