Experimental study on the mechanism and countermeasures of recharge plugging induced by soil particle migration

Abstract

Groundwater recharge is often performed to alleviate the environmental impacts induced by dewatering in excavation engineering. However, the application and widespread adoption of this method are hindered by plugging issue in recharge wells (RWs). The current studies on plugging have focused on the influence of impurities in recharge water, and studies on the effects of soil particle migration caused by seepage are lacking. On the bases of a self-designed model box, the mechanism of recharge plugging caused by particle migration in the process of recharge and mitigation measures were studied. The flow rate decreases with the recharge duration, and it presents a distribution pattern that an area with increased hydraulic conductivity near the RW and an area with decreased hydraulic conductivity far from the RW will occur in recharge process. The greater the recharge water pressure is, the greater the range of areas where the hydraulic conductivity decreases (approximately 2 m–2.2 m away from the RW) and the decreased ratio of hydraulic conductivity after stabilization (from 22 % to 31.5 %). The results of the analysis of the particle size distribution further indicate that seepage can cause the soil particles near the RW to migrate, leading to the accumulation of fine particles at positions away from the RW and eventually contributing to plugging. The soil particles in the model box can be quickly induced to migrate in the opposite direction by reverse recharge in the RW, which reduces the degree of plugging, providing a reference for alleviating RW plugging in engineering practice.