PS-InSAR技术在北京平原区地面沉降监测中的应用研究

北京市近60年长期超量开采地下水已经引起了严重的地下水水位下降和大范围地面沉降，截止到2009年最大累计沉降量达到1 096 mm，并以30~60 mm·y-1速率扩展，严重威胁城市规划建设和人民交通安全。相对于传统的水准测量、分层标等地面沉降监测手段，永久散射体干涉测量技术(PS-InSAR)可以快速获取高分辨率的地表形变细节信息。利用PS-InSAR技术和2003年12月—2009年3月Envisat卫星29景ASAR影像监测北京平原区地面沉降发展情况，发现北京平原区沉降漏斗已连成一片，沉降梯度变化较大地区主要分布在北京第四系凹陷区，覆盖面涉及朝阳、昌平、顺义、通州等区县，并有东移外扩趋势，平谷县境内出现新的沉降中心。沉降分布受前门—良乡—顺义、黄庄—高丽营、南口—孙河等主要断层控制，地面沉降与地下水水位变化具有明显相关性，呈现季节性下降(3月—6月)与回弹(11月—3月)趋势，并受弱透水层应力应变本构关系(弹性-塑性-黏弹性)影响。

Research on Monitoring Land Subsidence in Beijing Plain Area Using PS-InSAR Technology

In the present paper, the authors use permanent scatterers synthetic aperture radar interferometry (PS-InSAR) technique and 29 acquisitions by Envisat during 2003 to 2009 to monitor and analyze the spatial-temporal distribution and mechanism characterize of land subsidence in Beijing plain area. The results show that subsidence bowls have been bounded together in Beijing plain area, which covers Chaoyang, Changping, Shunyi and Tongzhou area, and the range of subsidence has an eastward trend. The most serious regional subsidence is mainly distributed by the quaternary depression in Beijing plain area. PS-Insar results also show a new subsidence bowl in Pinggu. What’s more, the spatial and temporal distribution of deformation is controlled mainly by faults, such as Liangxiang-Shunyi fault, Huangzhuang-Gaoliying fault, and Nankou-Sunhe fault. The subsidence and level of groundwater in study area shows a good correlation, and the subsidence shows seasonal ups trend during November to March and seasonal downs trend during March to June along with changes in groundwater levels. The contribution of land subsidence is also influenced by stress-strain behavior of aquitards. The compaction of aquitards shows an elastic, plastic, viscoelastic pattern.