Abstract:In order to control the input of engineering material and time, the rational selection of precipitation control measures in complex formations is realized. Based on the precipitation construction of deep foundation pit in the cut-and-cover section of the Jing'an intercity Yu'an No. 1 tunnel, the effects of finite element model analysis and on-site pumping test were used to study the effects of waterstop curtain insertion depth, single well pumping rate and pumping time on the precipitation effect of deep foundation pit.The results show that when the insertion ratio of water stop curtain is controlled at 1:0.9, the dewatering efficiency and cost input of foundation pit are optimal. The pumping time decreases rapidly and slowly with the pumping rate of a single well, but the trend becomes slow and the correlation weakens when it increases to a certain range. The optimal pumping rate of a single well is 125 m3 /d. From 1 to 7 days after pumping, the lower water level of sinkhole decreased greatly, reaching 95.2% of the maximum depth, and the precipitation scheme design was the most reasonable based on the water level depth reduction on the 7th day. It can be seen that scientific precipitation plan is not only helpful to water resources protection but also related to the safety and economic progress of project precipitation.