考虑气相作用的降雨入渗对非饱和土坡稳定性的影响

为了精细分析降雨入渗对非饱和土坡稳定性的影响，在考虑气相对降雨入渗过程的影响基础上，利用水-气二相流模型模拟入渗水流驱替土壤空气的水-气二相流过程，计算降雨入渗下土坡的孔隙水压力、孔隙气压力、基质吸力和含水量的变化；并建立了同时考虑由有效黏聚力、净法向应力，还有基质吸力引起的强度对边坡稳定的影响的非饱和土坡稳定分析模型．通过算例分析得出：无论是否考虑基质吸力的作用，由于降雨入渗改变了土体的净法向应力和土的容重，使得非饱和土坡的安全系数降低，而后的蒸发作用会使土坡的安全系数有所增大；在相同的渗流条件下，基质吸力的作用使同一滑动面上的安全系数增大．

Refined Analysis of Stability of Unsaturated Soil Slope due to Rainfall Infiltration Considering the Effect of Gas Phase

To achieve refined analysis of the stability of unsaturated soil slope induced by rainfall infiltration ,the influence of gas phase on the process of rainfall infiltration was considered. The water-air two-phase flow model was applied to simulate the process of water driving air in the pores of soil during rainfall infiltration ,and the variations of pore water pressure, pore air pressure, matric suction and water content were calculated. Then the stability analysis model for unsaturated soil slope was developed,in which the contribution of effective cohesion intercept,net normal stress and matric suction to the shear strength of unsaturated soil was taken into account. Based on the above approach ,the stability of slope due to rainfall infiltration was analyzed. The results show that whether or not the influence of matric suction is considered,the safety factor of unsaturated soil slope will decrease when the net normal stress and unit weight of unsaturated soil are varied by rainfall infiltration, and the safety factor of unsaturated soil slope will increase due to the evaporation. For the same seepage field and same slide surface, matric suction will increase the safety factor of slope.