渗流-应力耦合效应对非饱和土边坡稳定性影响分析

Analysis of Seepage and stress coupling effect on stability of unsaturated soil slope

基于VG模型得到土-水特征曲线与渗透系数函数曲线,通过建立有限元数值分析模型,采用有限元软件SIGAM/W与SEEP/W分别进行渗流-应力耦合分析与只考虑渗流的非耦合分析,将得到的渗流场与应力场导入SLOPE/W计算安全系数并对土坡内应力应变进行分析,研究耦合效应对边坡稳定性影响的相关规律。结果表明,渗流-应力耦合效应使得土体中雨水下渗速度更快,土中基质吸力消散更快;降雨对土坡稳定有不利影响,耦合分析土坡安全系数比非耦合分析小,耦合效应对非饱和土边坡稳定性影响不可忽略;降雨入渗条件下,土坡浅层出现应力集中现象,湿润锋深度处出现应力集中带,土坡易发生浅层破坏;坡脚水平位移比坡顶大,土坡失稳多从坡脚开始。

Soil- water characteristic curve and hydraulic conductivity function are determined based on VG model,and then by way of constructing finite element numerically analysis model,both seepage- stress coupling analysis and uncoupling analysis which only considering seepage are conducted by using finite element software SIGAM / W and SEEP / W respectively,factors of safety is calculated by software SLOPE / W using seepage field and stress field from coupling analysis and uncoupling analysis and analyze stress and strain to research the principle of coupling effect on slope stability. The results show that the rate of rain infiltration advance is faster due to seepage- stress coupling effect which results in faster loss of suction compared with uncoupling analysis. Rainfall has negative influence on slope stability,the factors of safety from coupling analysis is lower than that from uncoupling analysis,thus the influence of coupling effect on slope stability cannot be neglected. Stress concentration appears in surface layer and stress concentration belt appears at the depth of wetting front on the condition of rainfall infiltration,which means that slope is prone to shallow failure. Slope toe is the first region to failure because horizontal displacement in slope toe is higher than that in slope top.