基于改进时序InSAR技术的东莞地面沉降时空演变特征

Spatial-temporal evolution characteristics of land subsidence in Dongguan City based on improved InSAR technology

东莞市是珠三角城市群和粤港澳大湾区的重要节点城市,深厚欠固结软弱土及其诱发的地面沉降已成为湾区内代表性的区域地质灾害问题,影响城市地质环境安全。为研究东莞市地面沉降发育规律及时空演变特征,采用改进时序InSAR技术对覆盖东莞地区的137景Sentinel-1 SLC SAR影像数据进行处理,分析了2015年6月至2020年6月地表形变动态演化规律。结果表明:(1)全域内地表沉降变形整体较稳定,沉降发育区占市域面积的34.6%,变形严重发育区主要集中在麻涌镇、道滘镇、洪梅镇、中堂镇、沙田镇及滨海湾新区;(2)大部分沉降变形点处于缓慢发展变形阶段,年平均沉降速率在20 mm/a以内,累计沉降量在1000 mm以内;(3)结合形变监测和现场调查,认为地面沉降与深厚软土发育和人类工程活动的耦合作用有很强的相关性。证明该方法能较好地识别和反映城市复杂形态区地面沉降发育的时空演化特征,为灾害预警、减避及治理提供技术支持。

Dongguan City is an important city of Pearl River Delta urban agglomeration and Guangdong-Hong Kong-Macao Greater Bay Area.Deep unconsolidated soft soil and its land subsidence have become a representative regional geological disaster in the Bay area,affecting the safety of urban geological environment.In order to study the development features and spatial-temporal evolution characteristics of land subsidence in Dongguan City,137 sentinel-1 SLC SAR images covering whole Dongguan City were processed by improved InSAR technology,and the dynamic evolution characteristics of land deformation from June 2015 to June 2020 was analyzed.The results show that:(1)The land surface subsidence and deformation are stable in the whole region,and the subsidence developing areas account for 34.6%of the total urban area.The serious subsidence areas are mainly concentrated in Mayong Town,Daojiao Town,Hongmei Town,Zhongtang Town,Shatian Town and Binhai Bay New Area.(2)Most of the subsidence points are in the slow developing stage,the annual average subsidence rate is within 20 mm/yr,and the accumulated settlement is less than 1000 mm.(3)Combined with deformation monitor results and field investigation,land subsidence hazard has a great correlation with the coupling effect of deep soft soil development and human engineering activities.This method can better identify and reflect the temporal and spatial evolution characteristics of soft land subsidence development in urban area,and provide technical support for disaster early warning,mitigation and management.