## 5 Conclusions  
Based on the actual situation that the leakage of the enclosure structure will affect its deformation and the surrounding geotechnical body, the change of seepage flow field was studied by assuming different degrees of leakage with numerical simulation. The following conclusions were obtained:  
1. When there is no seepage point or when the seepage point is 10 mm wide, the drop of groundwater level outside the pit near the water stop curtain under the action of seepage flow force is about 20% and 30% of the depth of excavation and water drop in the pit, respectively. When there is leakage in the envelope, the local waterproof failure will lead to the abrupt change of the seepage field. When there is leakage in the envelope, the groundwater flow through the leakage of the envelope is greater than the flow at the bottom of the envelope. The total flow of groundwater into the foundation pit through the bottom of the retaining structure and the leakage is larger than the total flow into the foundation pit through the bottom of the retaining  
Figure 28: Comparison between numerical simulation and measured surface settlement. Figure 27: Comparison between numerical simulation and measured horizontal displacement of envelope structure. structure. Groundwater velocity and hydraulic gradient are also large in the envelope with leakage, which can easily lead to soil and seepage damages. 2. The horizontal deformation law of the enclosure structure is basically the same as the change law of the enclosure structure reflected by the numerical simulation results when considering the seepage point, but there is a certain difference in the value of the change. The total pressure at the outer wall-soil interface of the enclosure structure in the presence of leakage point decreases. The numerical simulation shows that the maximum deformation of the enclosure structure without a seepage point is about 53.3 mm, which is larger than the deformation value in the presence of a leakage point. The seepage point it caused the peak position of the horizontal displacement of the enclosure structure to show a sinking trend. 3. During the excavation of the foundation pit, when the water level is different, the surface deformation pattern around the foundation pit is basically similar and it is \"funnel-shaped\". In addition, the maximum position is shifted outward to a certain extent. However, the existence of leakage points will expand the influence scope of foundation pit settlement, resulting in greater adverse effects. 4. The finite element analysis results are close to the field monitoring results. The horizontal displacement of the enclosure structure and the surface settlement curve around the pit are almost the same with or without considering the effect of the seepage point, which indicates that the numerical simulation results are accurate. This finding provides guidance for further research on the treatment measures of seepage points of pits in water-rich areas. Inhibiting the expansion of seepage channels and stopping the aggravation of soil erosion are effective ways to control the deterioration of foundation pit seepage disaster. In addition, in order to reduce the risk of foundation pit seepage disaster, the foundation pit enclosure structure system should be reasonably selected to ensure the construction quality and seepage prevention effect of the water barrier structure. Conceptualization, B.C. ; literature search, B.C. ; investigation, B.C. ; experiment, B.C. ; methodology, B.C. ; data analysis, B.C. ; validation, B.C., Y.L. and S.D. ; formal analysis, X.Z. ; resources, Y.L. ; S.D. ; writing--original draft preparation, B.C. ; writing--review and editing, M.L. ; figures, B.C. ; supervision, M.L. ; project administration, Y.L. ; funding acquisition, T.L. All authors have read and agreed to the published version of the manuscript. Funded by the National Natural Science Foundation of China (Nos.