Experimental Study on the Surface Subsidence by Dewatering of Deep Foundation Pit in Confined Aquifer

Due to the influence of economic or technical factors, when the buried depth of the confined water layer is large at the location of the foundation pit, and the water flow inside and outside the foundation pit flows at the bottom of the diaphragm wall. To study the change of surface settlement outside the foundation pit caused by incomplete well dewatering in the foundation pit under the condition that the foundation pit is not completely isolated, taking a foundation pit of subway station in Shenzhen as an example, the model test and theoretical analysis are used to reveal the change law of water level caused by the seepage of typical confined water layer. The method for determining the effective influence depth of dewatering of incomplete wells in confined water layer, the formula of water level change curve outside the pit and the method for determining the range of seepage area are put forward. And based on the above theoretical research, the calculation method of surface settlement outside the pit considering the influence of seepage is proposed. Compared with the test, it can accurately reflect the change of surface settlement outside the pit considering the influence of surrounding infiltration. The above results can be provided as theoretical foundation for the study of surrounding surface deformation out of foundation pit caused by dewatering in foundation pit.