南水北调总干渠中线工程豫北段受矿区开采沉陷、区域地质构造活动及城市地下水开采沉降等多种威胁,区域地质结构稳定性较差.为了评估干渠沿线基础稳定性,为引水工程提供安全评价保障,以南水北调中线豫北段为例,利用2009年全年共9期ENVISAT ASAR雷达数据,采用二通加外部DEM的D-InSAR数据处理算法和“相位累积式”干涉测量甄别大气影响,采用“相邻重访周期式”干涉测量减小时间退相干影响,获得了沿线126km渠段、33个监测点在2009年8个时间段的时序差分形变相位图像;提取了不同时期采矿、地下水开采造成的地面沉降区及沉降幅度信息;评价了区域活动构造及稳定性.研究表明:研究渠段全线有不均匀下沉,350d累积最小下沉量为-33mm,最大下沉量为-73mm.年下沉速率0.34~0.76m/a,年平均下沉速率0.53m/a.监测点下沉总体符合指数分布,平均相关系数R2=0.741 8.根据监测点下沉拟合曲线预测,调水于渠多数段落基础下沉趋稳;南水北调中线工程豫北段受多种因素叠加影响,总体基础稳定性较差,地质构造活动、城市地表沉降为主要影响因素,基础施工为次要影响,矿区开采沉陷对基础失稳未见直接相关性.
Consisting of three water diversion projects,i.e.Western Route Project(WRP),Middle Route Project(MRP)and Eastern Route Project(ERP),South-to-North Water Diversion Project is by far the world’s largest water conservancy project.It is also a major strategic infrastructure to optimize the allocation of water resources in China.The MRP has a total length of 1267km,including a canal segment of 731km long located in Henan Province,which accounts for more than half of the total mileage and runs through from north to south the central plains of China.The project starts mainly in the north of Henan Province,running through Hebi mining area(i.e.Hebi Coal Industry Group Co.Ltd.),Tangyin graben,three cities(i.e.Weihui,Hebi and Anyang city) and two counties (i.e.Qixian county and Tangyin county).Being threatened by mining subsidence,regional tectonic activities and urban groundwater subsidence,its embankment is prone to instability.In order to assess the stability of embankment along the route,and also to provide safety guarantee for the water diversion project,with the case of the north Henan section of Middle Route Project(MRP),all 9 periods of ENVISAT ASAR data of 2009 are processed by means of 2 PASS plus external DEM D-InSAR processing algorithm,the parameters of space-time baseline are analyzed,best optimal interferometry images pairs are selected,and D-InSAR processing strategies are optimized to obtain differential interferograms for 33 monitoring points along 127km route;information of subsidence area,urban surface settlement area,as well as the amplitudes due to groundwater mining is extracted,and thematic maps of interferometric phase change vectors are gotten.The following understandings are obtained:1) There is uneven subsidence over the diversion canal.The cumulative minimum amount of subsidence is-33mm,and maximum subsidence is -73mm in 350 days.Annual subsidence rate is between 0.34m/yr to 0.76m/yr,and annual average subsidence rate is 0.53m/yr.In general,subsidence of monitor