Surface Deformation Monitoring And Hazard Evaluation Of Zhengzhou City Based On PS-InSAR Technology

China is one of the countries in the world with serious surface deformation.Surface deformation will threaten the safety of urban underground pipelines,road traffic,and building construction.As one of my country's national central cities,Zhengzhou has already experienced serious surface deformation.Monitoring of surface deformation and hazard evaluation is of great practical significance to the management of potential safety hazards in large cities such as Zhengzhou.This paper uses Sentinel-1 data and PS-InSAR technology to conduct surface deformation monitoring and hazard evaluation in the urban area of Zhengzhou City.The main work and results are as follows:(1)Used Sentinel-1 data and PS-InSAR technology,the surface deformation in the urban area of Zhengzhou was monitored.Obtained the surface deformation rate map of Zhengzhou urban area from 2015 to 2020 and the accumulated deformation variables of 121 time phases.The analysis found that the central surface of Zhengzhou City is mainly uplifted,with an uplift rate of0-10mm/a,and a maximum cumulative uplift of 76.8mm.There are 3 obvious settlement funnels around Zhengzhou City,two of which are located in the northwest,with a maximum settlement rate of 20mm/a and a maximum cumulative deformation of 97.2mm,and there is a trend of continuous expansion and connection;one is located in Zhengzhou City On the east side of the area,the edge of the settlement funnel is located in the study area;there are sporadic settlement areas in the northeast and southwest of Zhengzhou city.The article also analyzes the surface deformation of the subways,railways and the middle route of the South-to-North Water Diversion Project in the urban area of Zhengzhou City,and explains the potential safe areas.In addition,the second-class leveling measurement results are used to verify the accuracy of the obtained PS-InSAR monitoring results.The average error of the monitoring results of PSInSAR technology is ±1.99 mm/a,the median error is 2.35 mm/a,and the monitoring accuracy reaches the millimeter level.(2)Combined with the hydrogeological data of Zhengzhou urban area,this paper qualitatively analyzes the inducing factors of surface deformation in Zhengzhou urban area from the perspectives of faults and groundwater level changes.It is believed that the subsidence area in the northwest of Zhengzhou urban area and the uplift area of Zhengzhou downtown.The surface deformation on the north side is related to the fault;in addition,the main subsidence and uplift areas in the urban area of Zhengzhou are closely related to the changes in the mid-deep groundwater level.(3)The inducing factors detected by the geo-detector were used to evaluate the risk of surface deformation in the urban area of Zhengzhou.At the same time,the urban population density and GDP density of Zhengzhou are used for vulnerability assessment.The hazard assessment is carried out by combining the results of the risk assessment and the vulnerability assessment.The surface deformation hazard degree of Zhengzhou urban area is mainly medium and below,and the surface deformation hazard level of the central city area gradually decreases to the surroundings with the center of Zhengzhou city as the center of the circle.