库水位骤降时边坡渗透稳定的非饱和渗透参数敏感性分析

Seepage Stability Analysis of Deep Shallow Landslide with Sudden Drop of Reservoir Water Level under Different Unsaturated Parameters

为研究库水位骤降时边坡土体不同非饱和参数变动对边坡渗流特性及稳定性的影响规律,以某边坡计算模型为例,根据非饱和渗流原理,利用岩土软件Geo-slope2012模拟分析了不同工况下边坡深层浅层稳定性,同时考虑了Fredlund模型中三个非饱和参数a、m、n变动的影响。计算结果表明,不同非饱和参数(a、m、n)在库水位骤降下对上部监测点存在一个"影响深度","影响深度"与参数a、m呈正相关,与参数n呈负相关;随着距离库岸的缩短,边坡表层孔压变幅逐渐增大并超过深层孔压变幅;不同监测点位移变化呈现在库水位下降过程中迅速增大,在库水位下降结束后保持不变,参数a与最大位移呈正相关,而参数m、n与最大位移呈负相关;随着库水位的下降,边坡失稳顺序为下部浅层滑动面先发生失稳,然后引发深层的边坡失稳,而上部浅层滑动面在库水位下降的过程中不会发生失稳,研究结果为相应工况下边坡的认识与治理提供了相应的参考。

In order to study the influence of different unsaturated parameters of landslide soil on the seepage charac- teristics and stability of landslide under sudden drop of reservoir water level, according to the principle of unsaturated seepage, the simulation and analysis of different working conditions were carried out by using the geotechnical software Geo-slope2012. The impacts of the variation of three unsaturated parameters （a, m, n）in Fredlund model were discussed. The results show that different unsaturated parameters have a ＂influence depth＂ on the upper monitoring point under sudden drop of reservoir water level, ＂influence depth＂ has positive correlation with parameters a, m, and negative correlation with parameter n. As the distance from the bank decreases, the pore pressure amplitude of the surface of the landslide gradually increases and exceeds the deep hole pressure amplitude. The variation of displacement at different monitoring points increases rapidly in the process of water level decreasing, and remained unchanged after the water level dropped. The parameter a is positively correlated with the maximum displacement, while parameters rn and n are negatively correlated with the maximum displacement. With the decrease of reservoir water level, the sequence of landslide in stability is that the lower Shallow sliding surface first loses stability, and then causes deep landslide instability, while the upper shallow sliding surface does not lose stability in the process of reservoir water level decline. The research results provide a reference for understanding and treatment of landslide under the corresponding working conditions.