基于水气二相流的边坡降雨入渗有限元分析

为揭示边坡降雨入渗基本规律,基于水气二相流理论,以三峡库区大坪滑坡为例,采用有限单元法分析边坡降雨入渗水气运动规律。结果表明:根据水气流入、流出的方向不同,坡表可分为吸入区和溢出区,通常坡体上部为水、气吸入区,下部为水、气溢出区;水、气进出坡表的总速率受降雨特性、坡面产流情况、气温变化等外在因素的影响较小,具有相对稳定性;在坡表吸入区,当降雨强度大于水气入渗总速率时,入渗强度等于水气入渗总速率,吸入区产流;反之,入渗强度等于降雨强度,吸入区不产流。此外,坡表饱和区水压力可通过孔隙气传递到地下水面,增大地下水的压力水头,不利于坡体稳定。

Finite Element Analysis of Water-air Two-Phase Infiltration in Slope

On the basis of the theory of two-phase ( water and air) flow, the law of water-air movement caused by rainfall infiltration in slope was revealed by means of finite element method. Daping landslide in Three Gorges Res-ervoir was taken as a case study. The simulation results show that the slope surface can be divided into the inflow area and the outflow area according to the inflow and outflow of water and air. Usually the upper part of slope is in-flow area, and the lower part is outflow area. The total infiltration rate of water and air in slope is relatively stable, slightly affected by rainfall characteristics, slope surface runoff and temperature changes. In the inflow area, when rainfall intensity is greater than infiltration rate, water in slope will run off, otherwise water or air will completely infiltrate. The saturation pressure of slope surface could transmit to groundwater surface through pore air, which in-creases the groundwater pressure head, unfavorable for slope stability.