It is common to have a foundation pit accident

when failing to deal with the effect of confined water. In order to avoid such accidents

the Jiangnan foundation pit of Qingchun Road River-Crossing Tunnel in Hangzhou was investigated. By analyzing the monitoring data of wall deflection

settlement

confined water level and strut load

we proposed how to deal with high confined water. According to the analysis of on-site monitoring data

it could be obtained that: ①The wall deflection is closely related to the plane size of the foundation pit

and through strengthening the stiffness of the central support

the large pit can "be separated" into several smaller pit to control the wall deflection. ②The maximum settlement point is 0.5 times depth of the excavation away from retaining wall. ③It is useful to treat the confined water with dewatering and cut-off walls

and during excavating the bottom of the foundation pit

we must ensure that the pumping wells keeping working; otherwise the safety of the construction can be affected. ④ The load of the first strut becomes smaller and even can be tensile force during excavation.