Experimental Study And Numerical Simulation Of Land Subsidence Caused By Pumping And Recharging

With the wide application of groundwater source heat pump technology,the natural seepage field of groundwater in Tianjin Binhai New Area is not enough to make the groundwater source heat pump fully play the unit efficiency is increasingly manifested.Mainly because the Binhai New Area underground soil is mainly weak cohesive soil,groundwater seepage conditions are very poor.In order to solve this problem,the artificial seepage field has to be establied.However,the artificial seepage field can cause land to subside.Consequently,it is necessary to study the permeability,compaction and groundwater flow due to discharging and recharging.This can help determine the reasonable exploitation and pumping time for the scientific utilization of groundwater source heat pump,and provide building design and construction.In this paper,the pumping and recharging experiments are carried out different ways in the south of Haihe River Bridge in Tianjin Binhai New Area and numerical simulations are conducted.Based on the preceding research work,the following can be concluded:(1)In the process of extracting groundwater,the scientific and reasonable reduction of pumping times,pumping-recharging time and increasing the number of recharge can improve the efficiency of groundwater exploitation and recharge,so that the exploitation of groundwater can meet the demand and restore the groundwater level as soon as possible.(2)Under the action of periodic pumping and recharging,the clay layer will rebound firstly and then compacts,and the clay layer exhibits different deformation characteristics at different locations.(3)Under different pumping and recharging modes,the variation of settlement in each area has the same characteristics:the compression of each soil layer in the test area is positively correlated with the pumping flow and the contribution to the total sedimentation in the same time is consistent(4)When the single well 1s pumped,the water in the clay layer flows in the vertical direction.When the double wells are pumped and recharged,the clay layer between the two wells tends to flow horizontally.Other clay layers have it flows m other zones.(5)The double wells pumping-recharging mode can effectively improve the seepage in the pumping aquifer;it can also decrease the compaction of other soil layers.