用覆盖层土的浮重与渗透力计算基坑下承压水降深

通过对渗透力基本概念的分析,指出用覆盖层土的浮重与覆盖层内渗透力计算基坑下承压水降深比用覆盖层湿土重与层底水压力计算合理.通过两种方法比较说明,在基坑渗透稳定安全系数等于1,后一种方法中覆盖层用饱和土重计算时两者是一致的;但是,在基坑渗透稳定安全系数大于1时,通常前者计算的基坑下承压水降深小于后者;当基坑下承压水降深一定时,前者求得的基坑渗透稳定安全系数大于后者.用覆盖层土的浮重与覆盖层内渗透力计算基坑下承压水降深比较合理,宜于采用,但是相应的基坑渗透稳定安全系数可以适当提高.

Calculation of dewatering depth of confined water under foundation pits by use of submerged weight of overburden soil and seepage force

An analysis of the basic concept of seepage force shows that, for calculation of the dewatering depth of confined water, it is more reasonable to use the submerged weight of overburden soil and the seepage force acting on it than to use the wet weight of overburden soil and the water pressure at the bottom of the layer. The comparison of the two methods shows that, when the safety factor of seepage stability equals one, the calculated results of the two methods conform to each other if the weight of the saturated soil of overburden layers is used for calculation in the latter method; however, if the safety factor is larger than one, normally, the dewatering depth calculated by the former method is less than that by the latter method. Furthermore, it is concluded that, for a certain dewatering depth, the safety factor of seepage stability obtained by the former method is larger than that by the latter one. Therefore, the former method is more suitable for calculation of the dewatering depth of confined water. However, the safety factor of seepage stability should be properly increased.