摘要
以上海地质条件为基础,根据最近十几年分层标和含水层水位观测资料分析了上海地面沉降的主要沉降层,分析结果表明目前上海的主要沉降层是第五砂层。从第五砂层水位与时间的关系、变形与时间的关系和水位与变形的关系出发,结合室内实验的结果,指出第五砂层的变形特征是地下水位在一定范围内反复上升-下降时,变形以弹性为主、一般情况下则以塑性变形为主、应力应变关系为非线性以及存在蠕变变形。在建立地面沉降模型时必须考虑含水砂层的这些变形特点。
Stratum in Shanghai included six sand layers, six hard clay layers, three soft clay layers and one surface layer. Six sand layers were unconfined and five confined aquifers respectively. And there were a lot of measured data about deformation of soils due to pumping and corresponding water level. Based on data from layered marks and observation wells and on hydrogeological and engineering geologic conditions of Shanghai region, it was pointed that prominent subsidence layer was fifth sand layer now. A series of uniaxial compression tests were done for this sand so that its properties of deformation can be recognized for us. Tests included loading test and loadingunloading test, variation of deformation with time was observed at each loading stage. Studying hydrographs of representative wells and relation of deformation to time, relation of the deformation to water level and results of indoors tests, characteristics of deformation of fifth sand layer were obtained. They are as follows: a) It behaves elastic when groundwater level oscillates at a certain level; b) It is primarily plastic at usual; c) Relation of stress to strain is nonlinear; d) It is creepy. It is necessary to consider them when creating the model of land subsidence.
出处
《水文地质工程地质》
CAS
CSCD
2003年第5期6-11,共6页
Hydrogeology & Engineering Geology
基金
国家自然科学基金(40172082)
博士点基金(20010284002)资助项目。
关键词
上海
沉降层
变形特征
地面沉降
land subsidence
subsidence layer
characteristics of deformation
