Investigation of Land Subsidence Based on the Column Element Settlement Model in a Soft-Soil Area

The Su-Xi-Chang area is located in the Yangtze River Delta in southeastern Jiangsu Province, China. More than 2m cumulative land subsidence has occurred since 1980s. A range of monitoring programs, geological investigations, and numerical modeling has been implemented in order to establish a regional rehabilitation plan. In this paper, the column element settlement model (CESM) has been established to investigate the coupling effect of soil self-weight, upper loads, and groundwater withdrawal on land subsidence. The model has been verified by comparing with the land subsidence records in Changzhou and further applied to the investigation area. The results show that extensive groundwater withdrawal is the main cause of the land subsidence. Settlement caused by soil self-weight increases with the depth and decreases with upper loads, while settlement caused by upper loads increases with the intensity of upper loads and decreases with depth. The proportion of ground settlement caused by soil self-weight, upper loads, and groundwater withdrawal is also investigated.