Physical Modeling of Land Subsidence Induced by Triple Pumping on the Confined Aquifer

Land subsidence is the geological hazard caused by natural or human factors, resulting in a regional decrease in ground elevation due to the compression of the surface soil of the earth’s crust, which has brought huge losses to the national economy. The physical model tests were conducted to study the land subsidence induced by triple pumping including Pumping I, Pumping II and Pumping III. A total of 41 LVDTs were installed to monitor the settlement of the ground, and pictures of the front of the model were taken to obtain the section settlement via the particle image velocimetry (PIV) software. On Path 1, the subsidence is −1.40 mm, −1.50 mm, −1.86 mm, and −2.36 mm after Pumping I; it is −3.15 mm, −3.56 mm, −3.45 mm, and −4.57 mm after Pumping II; and it is −1.29 mm, −0.68 mm, −0.86 mm and −1.65 mm after Pumping III. The closer the soil is to the pumping well, the more severe the settlement after pumping. In the confined aquifer, the pore pressure in the soil experiences a process of initial decrease followed by an increase, which is the manifestation of the drawdown cone on pore pressure. In the layered settlement of the soil, compression in the upper and lower clay layers is significant, accounting for the majority of surface subsidence, while the confined aquifer experiences almost no compression. The results can offer a reference for the prevention and control of land subsidence in soft soil areas.