止水帷幕渗漏特征直接影响基坑工程安全,若能通过坑外水位变化特征定量分析渗漏位置和渗透系数,便能在基坑工程全生命周期控制地下水引起渗漏风险。本文通过建立有限元模型,采用正交试验分析水位降深对止水帷幕插入比、渗漏位置渗透系数比、观测孔位置(距深比)及渗漏位置四个因素敏感性,进一步分析各因素影响机理;根据水位降深特征曲线,提出渗漏位置渗透系数计算方法。结果表明:(1)敏感程度依次为渗透系数比>距深比>止水帷幕插入比>渗漏位置;(2)悬挂式止水帷幕和落底式止水帷幕,水位降深对渗透系数比和距深比敏感性不同;(3)存在临界渗透系数比,渗透系数小于临界值时,随着插入比增加,渗漏流量减小;当渗透系数大于临界值时,渗漏水量急剧增加,随插入比增加而增大,水力坡降变化是这种差异产生的原因;(4)水位降深差与距深比呈指数函数关系,与插入比和渗透系数比呈线性关系;(5)由水位降深曲线,联立求解可得到渗漏位置及其渗透系数。

The leakage characteristics of the water stop curtain directly affect the safety of foundation pit engineering. If the leakage location and permeability coefficient can be quantitatively analyzed based on the characteristics of water level changes outside the pit, the risk of groundwater leakage can be controlled throughout the entire lifecycle of the foundation pit engineering. This study establishes a finite element model and employs orthogonal experiments to analyze the sensitivity of water level drawdown to four factors: the insertion ratio of the water stop curtain, the permeability coefficient ratio of the leakage position, the observation hole position (distance to depth ratio), and the leakage position. Furthermore, the influence mechanism of each factor is further analyzed; Based on the characteristic curve of water level drawdown, a calculation method for the permeability coefficient of the leakage location is proposed. The results show that: (1) The sensitivity level is in the order of permeability coefficient ratio>distance to depth ratio>water stop curtain insertion ratio>leakage location; (2) The sensitivity of water level drop to the permeability coefficient ratio and width-to-depth ratio differs between suspended and bottom-type water stop curtains; (3) There is a critical permeability coefficient ratio, and when the permeability coefficient is less than the critical value, as the insertion ratio increases, the leakage flow rate decreases; When the permeability coefficient is greater than the critical value, the leakage water volume increases sharply and increases with the increase of insertion ratio, the change in hydraulic gradient is the reason for this difference; (4) The drawdown difference of water level has an exponential function relationship with the width depth ratio, and a linear relationship with the insertion ratio and the permeability coefficient ratio. The leakage location and permeability coefficient can be obtained by solving the water level drawdown curve together.