强透水地层水平帷幕作用下基坑渗流特性

Seepage characteristics of foundation pit with horizontal curtain in strong permeable stratum

为研究强透水地层水平帷幕作用下基坑渗流特性,基于Darcy渗流理论,建立了水平封底帷幕作用下基坑渗流计算模型,推导出基坑内涌水量及帷幕底部水压的理论解,并通过室内渗流试验,验证了理论计算方法的可靠性.分析了渗透系数比、帷幕厚度以及帷幕与基坑底部的距离对基坑渗流的影响.研究结果表明:渗透系数比对渗流的影响起主导作用,当渗流系数比为0.01时,涌水量仅为不设帷幕的10%;帷幕厚度对渗流具有一定影响,而帷幕位置对渗流几乎没有影响.建议强透水地层基坑水平帷幕渗透系数比不宜高于0.01,厚度不宜小于4 m.

To study the seepage characteristics of foundation pits with horizontal curtains in strong permeable strata,based on the Darcy's seepage law,foundation pit seepage calculation models with horizontal curtains were established.The theoretical solutions of the water inflow in the foundation pit and the water pressure at the bottom of the curtain were derived.The reliability of the theoretical calculation method was verified by the indoor seepage test.The effects of the seepage coefficient ratio,the thickness of the curtain and the distance between the curtain and the pit bottom on the seepage of the foundation pit were analyzed.The results show that the ratio of hydraulic conductivity plays a leading role in the seepage flow.When the seepage coefficient ratio is 0.01,the water inflow is only 10%of that without curtains.The thickness of the curtain has a little effect on seepage while the position of the curtain has almost no effect on seepage.It is recommended that the ratio of hydraulic conductivity of the horizontal curtain in a strong permeable stratum should not be higher than 0.01,and the thickness should not be less than 4 m.