开挖及降雨作用下土质边坡变形 破坏机理

本文基于现场变形调查和数值模拟分析,研究了华安县大坑村滑坡在人工开挖以及降雨条件下的变形特征,计算了不同开挖时步以及不同工况下的边坡稳定性系数,并探讨了该滑坡的变形破坏机理.结果表明:开挖过程中,边坡前缘抗滑阻力减小,前缘部位最先产生变形,牵引中后缘坡体表面产生张拉裂缝,降雨期间雨水沿裂缝渗入坡体,岩土体容重增加,岩土体抗剪强度降低,最终诱发深层滑移破坏.分析表明,人工开挖及降雨入渗是大坑村土质边坡产生深层滑移破坏的主要影响因素.深层滑移破坏后,边坡岩土体结构松散,在暴雨作用下,再次诱发滑坡前缘浅表层松散体产生圆弧面滑移破坏.

Analysis on soil slope deformation failure mechanism under slope excavation and rainfall infiltration

Based on deformation survey and numerical analysis, the process of slope deformation was studied during the slope cutting and under rainfall conditions. The slope stability factor of each excavation step also was calculated, and then the landslide deformation mechanism was investigated. The result shows that the leading edge of the slope occur deformation firstly because of resistance against sliding decreased, which entice develop tension cracks at the trailing edge of the slope. Rainwater infiltrate into the slope body along the cracks under the condition of rain, which makes bulk density of rock and soil increased, and its shear strength reduced, so that the deep sliding failure is emerged. The analysis shows that, as to soil slope of Dakeng village, excavation and artificial rainfall is the main factors of deep sliding. The structural of rock and soil become loose after deep sliding that induce shallow landslides easily at the leading edge of the slope under rainfall conditions.