Monitoring Of Ground Fissure Activity In Yuncheng Basin By Time Series InSAR And Mechanism Analysis

Yuncheng Basin is located in the southern part of Shanxi Province.Due to the special geological and geomorphological environment and the comprehensive activities of human activities,geological disasters occur frequently in this area,and land subsidence,ground fissures and fault activities are relatively active.In order to better study the development of ground subsidence and ground fissures in Yuncheng Basin,five sensor data were selected: Envisat ASAR,ALOS PALSAR,TerraSAR-X,Sentinel and Radsat-2 data,using time series InSAR technology(SBAS and StaMPS technology)monitored the ground subsidence and ground fissure development in Yuncheng Basin from 2007 to 2017 and analyzed it in detail.The main research work of this paper is as follows:(1)Introduced the StaMPS algorithm based on PS-InSAR technology,and the important steps such as PS point selection?3D unwrapping method and so on.The PS points are selected based on the amplitude discrete exponential threshold and the interference phase analysis method,and then the primary PS points are analyzed and eliminated by the phase-space correlation property.Secondly,based on the time-space filtering method,the terrain error,orbit error,atmospheric delay error and spatial viewing angle error are evaluated and eliminated.Thirdly,the three-dimensional unwrapping method is used to unwind the interference phase to improve the authenticity of the phase information.Finally,ground deformation information is obtained by phase conversion.(2)Using the StaMPS algorithm to monitor and analyze the ground subsidence and ground fissures in Yuncheng Basin.Selected 8 scenes Envisat ASAR data from February 20 th,2009 to October 8th,2010,21 scenes ALOS PALSAR data from December 22 th,2006 to January 2th,2011,36 scenes TerraSAR-X data from October 11 th,2011 to September 10 th,2015,and obtained the ground deformation rate map in three different time periods.Through the analysis of the monitoring results,there are obvious ground deformations near the Boyuan in Yanhu District and Xiaxian areas,and the ground deformation of Xiaxian area has changed to serious.By analyzing the time series deformation of the two feature points in the deformation areas,it is found that ground deformation in the region is uniform in the early stage,and the deformation speed is significantly reduced in the later stage.This phenomenon may be related to local groundwater restrictions.The time series analysis of the feature points was extracted on both sides of the ground fissure.Through the difference subsidence of the upper and lower plate,it is found that the ground fissure still has developmental activities.(3)In order to better analyze the mechanism of ground deformation and ground fissure,the line-of-sight deformation rate of Envisat ASAR and ALOS PALSAR data was decomposed in two dimensions(vertical and east-west),and the annual rate of surface subsidence and eastwest deformation rate map were obtained.The sill model was used to inversely simulate the vertical deformation value and the vertical deformation value of TerraSAR-X data,and the optimal parameters were obtained through multiple iterations.(4)Selected the 9 scenes Radarsat-2 data between January 3th,2016 and October 17 th,2016,and the 31 scenes Sentinel data between March 12 th,2017 and March 31 th,2018.Monitored surface deformation and ground fissure in Yuncheng Basin by SBAS technology,and obtained the surface deformation rate maps of two different time periods.(5)Based on FLAC3 D software,the influence of ground fissure on pumping activities was simulated.A ground fissure model was established,and the contact surface was established to simulate the existence of the fault.A pumping well was set up on the fault plate to simulate the pumping process.During the simulated pumping process,the horizontal displacement and vertical displacement of the soil around the ground fissure and the magnitude of the stress and strain were analyzed,and the causes of the displacement and stress strain were analyzed.Finally,by setting the pumping wells at different locations from the ground fissure,the effects of pumping on the ground fissure at different locations were observed,and the location suitable for pumping activities was obtained.