落底式止水帷幕条件下基坑涌水量计算研究

Water Inflow Calculation of Foundation Pit under the Condition of Bottom-type Waterproof Curtain

涌漏点的存在使得落底式止水帷幕条件下基坑涌水量的计算成为一个有待解决的技术难题。在承压含水层中开挖落底式深基坑时,针对落底式止水帷幕渗漏的不确定性,建立承压含水层中落底式基坑非完整井降水水文地质模型。基于Theis非完整井非稳定流理论,结合映射原理,推导等效渗透系数计算公式,并提出涌漏系数法用以评价落底式止水帷幕隔渗效果以及计算基坑涌水量。以武汉某深基坑降水工程为例,采用该方法评价止水帷幕的隔渗效果以及对其基坑涌水量进行计算,并与实测结果和传统方法计算结果分别进行对比验证。结果显示涌漏系数法计算误差较小,且计算过程简便,兼具安全性和经济性。研究结果可应用于指导工程设计,具有一定实际应用价值。

The water inflow calculation of foundation pit under the condition of bottom-type waterproof curtain is a technical problem to be solved because of the existence of leakage point.Aiming at the uncertainty of groundwater seepage in bottom-falling foundation pit,the hydrogeological model for dewatering of partially penetrating wells of bottom-type foundation pit in artesian aquifer is established.Based on the Theis theory of unsteady flow of partially penetrating wells and the mirror method,the calculation formula of equivalent permeability coefficient is deduced,and the leakage coefficient method is proposed to evaluate the effect of waterproof curtain and to calculate the water inflow of foundation pit.Finally,taking a deep foundation pit dewatering project in Wuhan as an example,the water inflow of the foundation pit is calculated by using the leakage coefficient method,and compared with the measured results and the calculation results of the traditional method.The comparison results show that the calculation error of the leakage coefficient method is slight,and the calculation process is simple.The research results can be used to guide engineering design,and have certain practical application value.