基于SBAS技术的宁波市轨道交通沿线地面沉降监测

Land Subsidence Monitoring along Rail Transit in Ningbo Based on SBAS Technology

随着城市化快速推进,轨道交通迎来大规模建设,由此带来的安全威胁也日益突出。本文基于44景覆盖宁波市轨道交通4条已运营线路的5 m分辨率Radarsat-2影像,采用小基线(SBAS)技术获取2016年12月~2019年12月地面沉降特征,并通过各线路的沉降速率剖面图系统地分析了轨道交通沿线地面沉降的空间分布规律。同时,以沉降比较明显的3号线、4号线为例,引入形变梯度以分析区域的不均匀沉降。监测结果显示:在以三江口为中心的老城区轨道交通沿线地面沉降情况相对稳定,处在运营期的1号线、2号线沿线地面沉降速率及影响范围,比处在施工期的3号线、4号线要大;在部分沉降速率较小的区域,形变梯度却比较大,表明该区域存在不均匀沉降。

With the rapid development of urbanization,rail transit has ushered in large-scale construction,and the resulting security threat is becoming increasingly prominent.Based on 44 images of the 5 m resolution Radarsat-2 data covering four lines that have been operated by Ningbo rail transit,this paper used Small Baseline Subset(SBAS)technology to obtain land subsidence characteristics from December 2016 to December 2019,and systematically analyzed the spatial distribution pattern of land subsidence through the deformation rate profile of each line.Besides,taking line 3 and line 4 with obvious subsidence as examples,the deformation gradient was introduced to analyze the uneven subsidence of the region.The results show that in the old urban area centered on Sanjiangkou,the land subsidence along the rail transit is relatively stable;and the deformation rate and influence range along line 1 and line 2 in the operation period are larger than those of line 3 and line 4 in the construction period.In some regions with low deformation rate,the deformation gradient is relatively large,indicating the existence of uneven subsidence.