Research On Fine Monitoring And Simulation Of Pumped Land Subsidence

Land subsidence is one of the most serious natural geological disasters today.Its formation is slow and difficult to detect.However,due to its greater harm,it has caused huge losses to the lives and economies of people around the world.Due to the insufficient understanding of the deformation mechanism of land subsidence,it is impossible to fully understand and grasp the disaster mechanism of land subsidence and predict the development law of land subsidence.The government cannot prevent the formation of land subsidence in time and issue prevention and control policies in advance to prevent land subsidence.harm.Therefore,a reasonable and effective geological body monitoring method is needed to monitor land subsidence in a refined manner.Distributed optical fiber sensing technology has huge advantages that conventional geological body monitoring technologies can't match.Its main feature is adaptability.It addresses the distributed,long-distance and large-scale monitoring requirements of various geological bodies in civil engineering,and is widely used in geological health monitoring in civil engineering.In this paper,using distributed optical fiber sensing technology,with ground subsidence caused by pumping as the research background,the soil deformation and pore water pressure changes in the Chenjiagang Central Primary School in Xiangshui County,Yancheng City are studied in a refined process.And simulated and studied the changes of the soil layers in the Chenjiagang area after pumping,and then compared the monitoring results with the simulation results.The main work and the research results obtained are as follows:(1)Deploy optical fiber sensors and sensing cables in a 350 m borehole in Chenjiagang Central Primary School,Xiangshui County,Yancheng City,and systematically divide the aquifer in the area,and design a full-section DFOS monitoring system for boreholes.It took up to two years of monitoring.(2)Perform detailed analysis of the monitoring results of the strain field,deformation field,and moisture field in the study area,conduct an in-depth analysis of the deformation trend of the soil,compression rebound,water level fluctuation and pore water pressure changes,and determine the aquifer deformation The relationship with the change of groundwater level explains the specific causes of ground subsidence caused by pumping water,and deeply explores the main factors that cause deformation of shallow aquifers and deep aquifers.(3)The three-dimensional finite element software ABAQUS was used to carry out a simulation study on part of the land subsidence area of Chenjiagang,and compared with the monitored data.The results show that the deformation trend of the soil layer above 250 m in the Chenjiagang area is basically similar to the monitored value,and the compression and rebound trend of the soil layer are basically the same;the pore water pressure simulation value of each aquifer is basically the same as the monitored value.However,due to the fact that there are too many variable factors in the actual project,the simulated value is smaller than the monitored value.