利用InSAR与地质数据综合分析南京河西地面沉降的演化特征和成因

Attribution Analysis on Land Subsidence Feature in Hexi Area of Nanjing by InSAR and Geological Data

  • 摘要: 河西地区是南京市重点发展区域,近年来遭受了严重的沉降地质灾害。为保证该区域可持续发展,利用永久散射体雷达干涉测量(persistent scatterer interferometric synthetic aperture radar,PS-InSAR)技术监测南京河西不均匀地面沉降,并对成因进行分析。首先,根据ALOS PALSAR和COSMO-SkyMed影像,采用PS-InSAR技术获取河西2007—2016年地面沉降信息,结果与同期水准数据一致,均方根误差(root mean square error,RMSE)不超过2.6 mm/a。其次,结合地质条件、分层沉降和地下水位资料对沉降成因进行分析,结果表明浅部地层的固结压缩是导致河西地区大面积不均匀沉降的主因。在此基础上,利用熵值法综合评估不均匀地面沉降对地铁结构健康的影响,结果表明,当主要沉降土层位于隧道下方时,地面沉降可能对地铁结构稳定性产生影响。

     

    Abstract: Hexi area is a key development region of Nanjing, which has suffered serious geological disaster of subsidence in recent years. To ensure the sustainable development, persistent scatterer interferometric synthetic aperture radar (PS-InSAR) was used to monitor the uneven land subsidence and the attribution was analyzed. Firstly, based on PALSAR and COSMO-SkyMed images, we used PS-InSAR technique to obtain the land subsidence in Hexi area from 2007 to 2016. The results were consistent with the leveling data in the same period, and root mean square error (RMSE) did not exceed 2.6 mm/a. Secondly, geological conditions, stratified subsidence and groundwater leveling data were combined to analyze the attribution of land subsidence feature. The results show that consolidation and compression of shallow strata is the main cause of uneven subsidence in Hexi area. The Entropy method was used to comprehensively evaluate the influence of uneven ground subsidence on the subway structure. The results show that the subsidence may affect the stability of subway structure when the main settlement soil layer is located below the tunnel.

     

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