管沟渗水下的黄土地基水分场数值分析

Numerical Analysis on Moisture Migration in Loess Foundation Considering the Effect of Pipe-Water Leak

基于实际工程管沟漏水的情况,考虑黄土地基土体初始含水量、孔隙比、管沟内积水压力等因素影响,给出了二维非饱和黄土地基管沟入渗的有限元计算模型,确定了模型参数,并编制软件对管沟渗水下的黄土地基水分场进行了计算分析。结果表明,土体孔隙比越大,初始含水量越大,入渗速度越快,地基增湿区域越大,但随着增湿区域的增大,入渗水量扩散作用增强,饱和区域反而减小。土体孔隙比越小,初始含水量越小,入渗速度越慢,地基增湿区域越小,显示了低饱和密实土体较强的阻水作用,水分难以下渗,主要集中于管沟周围,水分扩散作用较弱,饱和区域反而大。随着时间的增长,入渗增湿范围增加。但当地沟水与地下水连通后,由于入渗通道的形成,地沟水能够更快的进入地下,则增湿范围反而减小。管沟中积水压力的大小对黄土地基水分入渗影响很大,压力越大,入渗越快,增湿范围越大。

On the basis of actual pipe leakage, considering the factors as initial loess soil water content, void ratio, water pressure in pipe, a numerical model of moisture migration in unsaturated loess foundation is given. The pressure of water in pipe trench is considered in two cases, with or without pressure respectively. The results showed that the greater the soil void ratio and the greater the initial moisture content, the faster the infiltration, the greater the humidifying region of foundation would be, but with the increase of the humidifying region, enhancing diffusion of infiltration water, the saturated region was reduced instead. The smaller soil void ratio and the smaller initial moisture content, the slower infiltration rate and the smaller ground-based humidifying region would be, showing the strong role of dense low-saturated soil in water blocking, the water diffusion is weak and the water mainly concentrated in groove around the tube and the saturated region was great. With the time, the scope of infiltration and humidification increase. However, when the water in trench and groundwater were connected, due to the formation of infiltration channel, the trench water could enter into the ground faster, the scope of the humidifying region reduced. The water pressure in the trench had a great influence on water infiltration in loess foundation, the greater the pressure, the faster the infiltration, the greater the scope of humidifying region would be.