基于PS-InSAR技术的天津地面沉降研究

Detection of land subsidence in Tianjin based on PS-InSAR technology

地面沉降是天津地区主要地质灾害之一。文中采用永久散射体干涉测量(PS-InSAR)技术获取天津地面沉降时间序列演变特征,分析不同含水层系统地下水开采、活动断裂对地面沉降的影响。研究发现:(1)天津地区地面沉降分布差异性较大,不均匀沉降特征明显,西南部地区为沉降重灾区,并有东移的趋势;(2)地面沉降漏斗多发生在地下水超采区内,沉降中心与地下水漏斗中心并非完全吻合,可能由于软土层固结速度滞后于地下水水头变化所致,并且与软土层厚度有关。中深部承压含水层地下水开采对地面沉降影响较大,是地面沉降的主要贡献层;(3)天津地面沉降存在明显的构造控制特性,主要受海河断裂、沧东断裂和天津断裂影响,断层两侧形变梯度较大。

Land subsidence is one of main geological disasters in the Tianjin area. In the past decades,the scope and magnitude of land subsidence has expanded from year to year. This paper uses the permanent scattered interferometry( PS-InSAR) technology to obtain time series of land subsidence evolution characteristics in Tianjin. The impact of groundwater exploitation in different aquifer systems and active faults on land subsidence are analyzed. The results show that( 1) the difference of spatial distribution of land subsidence is great in the Tianjin area,and uneven settlement characteristics are obvious. Southwest is the most serious area and the trend of land subsidence exists eastward.( 2) Land subsidence funnel mostly occurs in the region of groundwater over-exploitation,and the land subsidence center does not completely overlap the groundwater funnel center. The reason for this is that soft soil consolidation speed may lag behind the groundwater head changes,and is related to the thickness of soft soil. Groundwater exploitation in the deep confined aquifer has a more seriously impact on land subsidence,which is the main contribution layer of land subsidence.( 3) Land subsidence by tectonic controls is significant,mainly controlled by the Haihe,Cangdong and Tianjin fault. The deformation gradient is great on both sides of the faults.