Study On The Field Pressure Recharging Experiment In Shallow Groundwater

In foundation pit engineering, groundwater recharging is often used to solve the problem of uneven settlement of surrounding ground and waste of water resources caused by the dewatering of foundation pit. As a more efficient and reasonable way of groundwater recharging, the research of pressure recharging is very important in engineering application. At present, there are few studies on the technology of pressure recharging and the related regulations, and there is no systematic theory and specification,so it is very necessary to explore and test the engineering application of the technology of pressure recharging technology which is not yet mature.In this paper, on the basis of pressure recharge technology research status, development trends and relevant theory are systematically discussed and analyzed at home and abroad, through the different structures of the control system with variable frequency and constant pressure to control the use of recharge wells and positioned at the periphery of the observation wells of pressure recharge the related experimental study. Secondly, the field test of hydrogeological conditions and pressure recharge construction technology, tube well design and test parameters are systematically analyzed. Finally, the advantage of the pressure recharging, witch compared with pressureless recharging, the relationship between the recharged pressure and the recharge volum, the structure of the tube well, the radius of influence, the arrangement of the recharge well and the choice of optimal pressure recharging are deeply discussed and investigated. The main research results are as follows:1、Through the field test and analysis, the pressure recharging is the way to solve the uneven settlement of the ground around and the waste of water resources after the dewatering of foundation pit.2、The test’s process and results show that the variable frequency constant pressure control system designed by the research group is reasonable and practical.3、Through the comparative analysis of the experimental data and the economic aspect, it is concluded that the 0.05MPa-0.1MPa is a more economical and efficient time when the pressure is recharged.4、Through the effect of the different tube structure on the recharge volum, the opening rate of the pipe wall meets certain requirements, pipe wall mesh using 40 mesh nylon mesh to make the mesh is a more economic and reasonable way; The well sealing material selection of cement mortar has better sealing effect of the upper part of the filter tube.5、The distance between the wells can be based on the amount of field precipitation and site conditions, in ensuring that the two wells do not occur under the premise of soil damage for the safety spacing, it is recommended that the distance between the two wells is greater than 3m.6、Experimental results show that with recharge pressure(less than 0.2MPa) increased, the radius of influence of the recharge well is also increasing, but it has little difference. The influence radius of pressure recirculation can be calculated by the modified Kusaki formula.