Experimental Study on Groundwater Dewatering and Recharge of Deep Foundation Pit of a Subway Station in Jinan Water-Rich Area

Abstract

A large amount of groundwater dewatering is beneficial to the foundation pit construction, but it will cause surface collapse, waste groundwater resources and damage the groundwater environment. In order to maintain the stability of groundwater level and the safety of surrounding buildings in the construction of deep foundation pit, the combination of dewatering and recharge is adopted. Taking the construction of deep foundation pit of a subway station in Jinan water-rich area as an example, the theoretical model of recharge quantity, stratum parameters and groundwater level was obtained through the backward derivation of the precipitation calculation model. 78 dewatering wells and 78 recharge wells were designed, and the on-site dewatering and recharge teat was carried out. The test results show that the water level of a single dewatering well decreases sharply in the initial stage of precipitation, and then the depth drops gradually to a stable level, and finally maintains a fixed value. The water inflow of a single well ranges from 34.54~57.07 m³/d, and the groundwater level can be lowered to 1.53~2.79 m below the foundation pit floor. The recharge volume of a single well in the natural recharge state is 146.88~ 241.44 m3/d, and the higher the recharge pressure, the stronger the recharge capacity of the recharge well. Through field test research, it is found that the recharge capacity of single well of recharge well is much greater than the pumping capacity of single well of dewatering well, and 56 recharge wells can make the recharge rate reach 100%, which optimizes the dewatering and recharge design of deep foundation pit.