利用GPS与InSAR研究西安现今地面沉降与地裂缝时空演化特征

Research on recent characteristics of spatio-temporal evolution and mechanism of Xi'an land subsidence and ground fissure by using GPS and InSAR techniques

西安孕育严重的地面沉降及地裂缝灾害,严重制约着城市的现代化发展,本文采用GPS精密定位和InsAR遥感差分技术对西安地面沉降和地裂缝进行变形监测与分析,获取了西安地面沉降与地裂缝整体变形现状的珍贵信息,通过对这些变形信息的研究分析,揭示了西安现今地面沉降与地裂缝时空演化特征和机理:随着停止或限采地下水,西安地面沉降量级由20世纪90年代中期的最大年沉降速率20～30 cm/a减少到不足10 cm/a,且超过60%的沉降区域的年沉降速率已由90年代中期的5～8 cm/a减少到不足2 cm/a;原有的沉降中心大部分已不存在或大大减小;地裂缝在时空活动与分布上与地面沉降存在明显的关联性;地面沉降和地裂缝随着西安高新区的建设向南、西南、东南逐步扩展.

Xi＇an city, one of the famous historical cities in China, has been suffering serious land subsidence and ground fissure historically and even recently, which greatly restrict the modernization of this city. This study focuses on the monitoring and analysis of Xi＇an land subsidence and ground fissure by applying the GPS and InSAR techniques. On the one hand, we achieved precious information of the overall deformation caused by both land subsidence and ground fissure. Based on the information, on the other hand, we studied the characteristics of spatio-temporal evolution and mechanism of the land subsidence and ground fissure, and obtained the following main conclusions. Firstly, owing to the effective controlling of underground water withdrawal, the maximum annual subsidence rate has decreased greatly from 20-30 cm/a in the mid-1990 s to less than 10 cm/a recently. Meanwhile the mean land subsidence rate of approximately 60% subsidence areas has decreased from 5-8 cm/a to 2 cm/a. Secondly, most of the original subsidence cones have disappeared or greatly reduced. Thirdly, we discovered obvious spatio-temporal correlations between ground fissure and land subsidence. Lastly, the land subsidence and ground fissure have gradually extended to south, southwest, and southeast suburbs of the city along with the expanding of the Xi＇an Hi-tech zones construction.