兰州新区平山造城竣工后地表形变InSAR时序监测与分析

InSAR Time Series Monitoring and Analysis of Land Deformation After Mountain Excavation and City Construction in Lanzhou New Area

兰州新区是西北地区发展的重要窗口,近年来其大范围的平山造城导致不同程度的地面沉降,严重威胁了新区的经济社会发展。以兰州新区为研究对象,利用小基线集干涉测量(small baseline subset interferometric synthetic aperture radar,SBAS-InSAR)技术对覆盖研究区2017-05—2021-02的58景升轨Sentinel-1A影像数据进行处理,获得研究区地面沉降的分布特征及时空演化规律,并通过野外实地调查验证了SBAS-InSAR的测量结果,探讨了影响地面沉降的相关因素。结果表明,兰州新区地面沉降主要集中于平山造城的区域,面积约33.5 km2,最大沉降速率为−68 mm/a。地面沉降在空间上随着挖填方工程的开展向新区的东南方向发育,且地表呈长期持续的沉降过程。地面沉降与平山造城工程、挖填方厚度、地质、道路等多种因素密切相关,其中平山造城工程控制地面沉降的范围,填土厚度则控制了地面沉降的量级,而人工填土的性质是引起地面沉降的内在因素,同时道路建设会加快地面沉降的过程。研究结果可为新区的持续安全发展和城市规划建设提供科学依据。

Objectives:Lanzhou New Area is an important window for the development of northwest China.In recent years,the large-scale construction of mountain excavation and city construction project has led to different degrees of land subsidence,which has seriously threatened the economic and social development of the new area.Methods:Taking Lanzhou New Area as the research object,this paper uses small baseline subset interferometric synthetic aperture radar(SBAS-InSAR)to process 58 ascending Sentinel-1A image data covering the study area from May 2017 to February 2021.The distribution characteristics and spatio temporal evolution of land subsidence in the study area were obtained,and the SBAS-InSAR measurement results were verified by field investigation.Then the related factors affecting land subsidence were discussed.Results:The results show that land subsidence in Lanzhou New Area is mainly concentrated in mountain excavation and city construction area,with an area of about 33.5 km2 and a maximum subsidence rate of−68 mm/a.In space,with the development of excavation and filling projects,the land subsidence develops to the southeast of the new district,and the land surface presents a long-term continuous settlement process.Conclusions:Land subsidence is closely related to many factors such as mountain excavation and city construction project,thickness of excavation and filling,geology and road.Specifically,mountain excavation and city construction project control the spatial extent of land subsidence,and then the filling thickness control the magnitude of land subsidence.The nature of artificial fill is an intrinsic factor causing land subsidence,while road construction will also accelerate the process of land subsidence.The research results can provide scientific basis for the sustainable and safe development of the new district and urban planning and construction.