Monitoring And Analysis Of Land Subsidence In Typical Plain Areas Based On SBAS-InSAR

Land subsidence is a major regional environmental geological disaster in the Yangtze River Delta Plain and the North China Plain.Nanjing,as the second largest city in the Yangtze River Delta Plain,has found serious geological disasters such as ground fissures in the urban area.In addition,Fuyang,as the main road of north-south traffic in the North China Plain and the transitional zone of industrial transfer in the developed eastern regions,has a unique location advantage of connecting the east to the west and connecting the south to the north.Phenomena such as mined-out collapse and excessive groundwater exploitation have been found in the city.At the same time,with the rapid economic development,the rapid growth of the population,the sharp increase in groundwater extraction and the expansion of urban engineering construction,the land subsidence problem in Nanjing and Fuyang has become increasingly serious.It is of great practical significance and economic value to carry out deformation monitoring.Due to the high cost and small scope of traditional land subsidence monitoring methods,large-scale subsidence monitoring cannot be carried out.The Small Baseline Subset InSAR(SBAS-InSAR)technology evolved from Differential InSAR(D-InSAR)can effectively make up for the shortcomings of traditional measurement methods and overcome the spatial and temporal de-correlation and atmospheric problems in D-InSAR.It is widely used in subsidence monitoring in plain areas.Therefore,in order to study the causes of land subsidence of typical landforms in the plain area,this paper monitors and predicts the two study areas based on the SBAS-InSAR technology.The main research contents are as follows:(1)In view of the problems of building cracking,highway deformation and long and narrow ground fissures in Nanjing,this paper monitors the ground subsidence in Nanjing based on SBAS-InSAR technology,and analyzes the impact on the ground in combination with Nanjing subway construction,precipitation and fault data.cause of subsidence.The monitoring results show that the land subsidence in Nanjing presents the phenomenon of uneven subsidence.The subsidence is mainly concentrated in the northeast of Jianye District and the south of Gulou District in Nanjing City.The land subsidence in this area develops from south to north.The urban land subsidence of Nanjing is related to subway construction,precipitation changes and earthquake faults.(2)In view of the complex stratigraphic structure,frequent goaf subsidence and excessive exploitation of groundwater in Fuyang,this paper monitors the land subsidence of Fuyang City based on the SBAS-InSAR technology,and divides the land subsidence risk area for Fuyang City according to the monitoring results.The monitoring results show that:Fuyang City presents uneven subsidence as a whole,and its subsidence is mainly distributed in five regions.Moreover,the land subsidence of Fuyang City is mainly affected by the comprehensive influence of stratum lithology,neotectonic movement,engineering construction and upper ground load.(3)In view of the non-linear and non-stable characteristics of land subsidence sequences,the subsidence monitoring results in Nanjing and Fuyang areas were predicted and analyzed by combining the GM-BP neural network combination model and the ARIMA model,and the GM-BP neural network was compared.Combining the applicability of the model and the ARIMA model,and establishing different prediction models according to the characteristic points of Nanjing and Fuyang,to reveal the future development trend of land subsidence in the two cities.