摘要:
针对珠三角地区广泛分布的地表水、植被易造成合成孔径雷达干涉(interferometry synthetic aperture Radar, InSAR)技术失相干和多云多雾多雨高湿的气候易造成严重的InSAR大气延迟“噪声”的问题,以珠三角东南部的深圳市龙岗区为研究区,采用干涉相干性最优原则生成小基线集技术(small baseline subset InSAR,SBAS InSAR)干涉像对连接图,使用35景Sentinel-1A影像获取了2019年9月—2020年11月龙岗区的地表形变信息,而后与永久散射体InSAR技术(persistent scatterer InSAR,PS InSAR)反演结果进行对比,最后分析、推断了地表形变成因。结果表明: ①SBAS InSAR和PS InSAR反演的地表形变场基本一致,SBAS InSAR在大形变量区域的相干点密度远大于PS InSAR,说明干涉相干性最优原则的SBAS InSAR反演结果准确、可靠,反演完整形变场更具优势; ②龙岗区及周边的地表形变成因主要有持续强降雨触发的岩溶塌陷或斜坡失稳,工业采排水导致的地下水文地质环境变化,地下施工引发的采空沉降,新建高层建筑施加的地基静荷载等。研究技术路线可为珠三角地区地质灾害隐患InSAR早期识别的自动化、工程化应用提供借鉴。
Abstract:
In the Pearl River Delta (PRD) region, widespread surface water and vegetation are liable to cause interferometric synthetic aperture Radar (InSAR) interference decoherence, and the cloudy, foggy, rainy, and humid climates frequently cause severe atmospheric delay noise in InSAR data. Accordingly, targeting the Longgang District of Shenzhen City in the southeastern PRD, this study generated the connection graph of interference image pairs using the small baseline subset and InSAR (SBAS InSAR) technique based on interference coherence optimization. This study also obtained the surface deformation information of Longgang District from September 2019 to November 2020 based on 35 scenes of Sentinel-1A images. It then compared the surface deformation information with the inversion results obtained using the persistent scatterer InSAR (PS InSAR) technique. Finally, this study deduced the causes of surface deformation. The results are as follows: ① The inversion results of SBAS InSAR and PS InSAR yielded almost the same surface deformation fields. SBAS InSAR exhibited a much higher coherent point density than PS InSAR in the region with high-amplitude deformation. This indicates that the SBAS InSAR based on the optimal interference coherence can yield accurate and reliable inversion results, enjoying more advantages in the inversion for a complete deformation field. ② The primary causes of surface deformation in Longgang District and its surrounding areas include unstable Karst collapse or slope triggered by continuous heavy rainfall, the changes in the underground hydrogeological environment caused by industrial mining and drainage, the subsidence of mining gob induced by underground construction, and static foundation load imposed by new high-rise buildings. The technical route of this study can provide a reference for the automation and engineering application of InSAR in the early identification of geological hazards in the PRD region.
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