沧州市地面沉降研究及防治对策

河北省沧州市发生了严重的地面沉降，至2001年的30年间，沧州市沉降中心的地面沉降量已超过2m，导致了城市内涝积水，河床下沉，影响南水北调等引水工程安全。经研究提出了地下水等液体资源的过量开采是诱发地面沉降的主要原因，而厚大的粘性土层为地面沉降的发生提供了物质基础。粘性土的释水压缩的永久性决定了地面沉降的不可逆性。通过不同时期沧州市地面沉降累计沉降量和地下水位降深的相关分析，建立了二者之间的相关公式，提出了警戒水位降深(临界)值(40m)和限制降深(止采)值(70m)，并进行了地面沉降发展趋势预测。文中提出以调控地下水位为主，避让和工程措施相结合的防治对策，以期对沧州市地面沉降防灾减灾工作有所促进和帮助。

Surface Subsidence and its Countermeasures in Cangzhou City

A serious land surface subsidence occurred in Cangzhou City, Hebei Province. In the subsiding center of Cangzhou City, the land surface had sunk for 30 years by 2001 and the subsidence amount reached more than 2 m, which caused waterlogging of some segments in the city. And the subsidence in the river bed will seriously influence the security of the Water Transfering Project From South to North China. Our investigation indicates that the surface subsidence is mainly caused by over pumping groundwater.The thick-bedded clay layer is under the city, which provides the material for the land subsidence, under the big pressure, if the clay gives out the water in it, that means the land surface cannot be rebound. According to the analysis between cumulative subsidence and the groundwater table depth, the relative expression is established. The warning water table depth (critical va-lue) is 40 m and limited depth (stop pumping) is 70 m, and the trend of the land surface subsidence is forecasted. The countmeasure for land subsidence to control groundwater table is proposed too.