Design of Open Dewatering of Deep Foundation Pit and Its Impact on Surface Subsidence

In order to preferably provide some experiences to the dewatering engineering of the deep foundation pit engineering in Wuhan,this paper takes the deep foundation project with open dewatering in Wuhan Center as an example and introduces the dewatering plan of a deep foundation pit with large area and deep drawdown in the interbedded soil area in Wuhan and its impact on surface subsidence.Firstly,the paper adopts conventional design methods of dewatering to calculate the yield of the deep foundation pit,well depth,the number of wells and the pumping load of the single well,and uses Tian Han dewatering software to simulate the dewatering process,with the results being consistent with the calculation results.Secondly,the paper adopts hierarchical settlement formula to calculate surface subsidence around the pit,and the results are compared with the actual monitoring results.At the end,the paper preliminarily analyzes the dewatering process based on the monitoring data of water level and surface subsidence,and the results show that the dewatering of foundation pit should be about 20~ 30days ahead of the excavation of foundation pit and should take on layering and partitioning.The paper puts forward four measures for the control of surface subsidence and the study can provide some reference for the design and construction of other similar projects.