Application Research Of Time Series InSAR Technology In Deformation Monitoring Of Central Line Project Of South-to-North Water Diversion

In recent years,geological disasters have occurred frequently,seriously endangering the safety of the life and property of the country,social and individuals,such as coal mining subsidence,ground settlement,and landslides.The direct and indirect economic losses that our country suffers each year as a result of various geological disasters are numerous.The Central Line Project of South-to-North Water Diversion is a large-scale water conveyance building in China.The main canal has a large span and a different direction.It is very necessary to carry out disaster investigation and risk assessment by relying on advanced earth observation technology to respond to the national disaster prevention and mitigation strategy,protect people’s lives and property,and also have great significance for realizing sustainable socio-economic development.An advanced Space-to-Ground observation technology,the Synthetic Aperture Radar Interferometry(InSAR)technology,which can achieve high-precision,large-area monitoring,has been widely used in various types of deformation monitoring.Over the last three decades,InSAR technology has evolved from traditional Synthetic Aperture Radar Differential Interferometry(D-InSAR)to advanced Multi-temporal InSAR technology such as Permanent Scatterer Interferometry(PS-InSAR)and Small Baseline Sets technology(SBAS),Pixel Offset Tracking and Multi-aperture Interferometry(MAI),etc.The conventional D-InSAR technique is difficult to obtain reliable results in surface deformation monitoring because of its observation geometry limitations.To address the above questions,this paper uses Sentinel-1A and RadarSat-2 data as data sources to conduct deformation monitoring research on the Central Line Project of South-to-North Water Diversion.The main content and achievements of this thesis are as follows:(1)the SBAS technique was used to process the acquired 90 scenes of Sentinel-1A data from April 2015 to March 2019,the maximum deformation rate of Jiaozuo and Huixian cities across the middle line of the Central Line Project of South-to-North Water Diversion reached 180mm/year.The 13 subsidence centers are evenly distributed along the main canal of the Central Line Project of South-to-North Water Diversion and far away from the main canal,which has no direct impact on its safe operation.(2)Comprehensive Jiaozuo coal mine distribution map and historical unbiased image data of Google Earth,among the 13 subsidence centers,the settlement of P1,P4,P5,P8,P9,P10 was caused by coal mining,the settlement of P2,P3,P6,P7,P11,P12 and P13 was caused by non-coal mining.In order to further investigate the trend of the shape variables of the 13 subsidence centers with time,curve fitting of the cumulative settlements of 13 settlement centers for 4 years,which all conformed to one-dimensional quadratic polynomial distribution.(3)Using distributed scatterer target technology to process the Sentinel-IA and RadarSat-2 data covering the main canal of the Huixian section of the Central Line Project of South-to-North Water Diversion,the shape velocity rate along the main canal of the Huixian section is-40～40mm/year,and the settlement area is mainly distributed near the thin-walled town and Shimen River section.By comparing with the leveling data,the results are basically consistent,and the reliability of Sentinel-1A data distributed scatter technology in the deformation monitoring of the Huixian main channel is verified.(4)The geological conditions of the Huixian section of the Central Line Project of South-to-North Water Diversion are special.The deformation mechanism of the swollen rocky soil and wet loess canal section of Huixian section is obtained by analyzing the deformation rate obtained and the two hydrological factors of rainfall and soil moisture changes respectively.In particular,the cumulative settlement of expansive rock and the periodicity of soil moisture are consistent,with fluctuations getting closer to the zero level over time,while the wet-subdued loess drainage section shows a definite downward trend over time.Therefore,it is important to strictly prevent damage to foundation buildings caused by wet-sedimented loess.