复杂条件下软土地区地下水开采引起的地面沉降计算理论研究

Land subsidence induced by groundwater pumping has become the serious environmental geology disaster restricting the city construction and economical growth in the zone of soft soils such as Changjiang Delta. However,almost all of the available theory for land subsidence evaluation cannot fully consider the nature property of soft soil such as nonlinearity,creep and structure,etc. It is thus difficult to predict reasonablly the arise and development of land subsidence,and harmful to the prevention of land subsidence.In this project, new theory for the land subsidence evaluation will be established taking condideration of not only non-Darcian flow but also complicated property of soft soil such as nonlinearity and creep through the systematical theoretical study combined with laboratory test and field measurements.On this basis, the influences of the complex factors such as non-Darcian flow and nonlinear property of soft soil on the behaviour of land subsidence will be investigated, and the law of land subsidence developing with time and space will be revealed.The work of the project is helpful for the carry out of the plan of land subsidence prevation made by Chinese government,and can provide more reasonable and more effective theory and technique for the land subsidence evaluation and prevention.

地下水开采引起的大面积地面下沉已成为严重制约长江三角洲等软土地区城市建设和经济增长的环境地质灾害。但目前现有的地面沉降计算模型均不能充分考虑软土固有的非线性、流变性、结构性等特性，难以合理准确地预测地面沉降的发生和发展，不利于对地面沉降的有效防控。本项目拟通过系统深入的理论研究并结合室内外试验和测试结果，提出和建立能综合考虑软土非线性、流变性、结构性、非达西渗流等复杂条件的大应变全耦合地面沉降计算理论。在此基础上, 详细分析非达西渗流和软土的非线性等复杂因素对软土地区地面沉降性状的影响, 揭示地面沉降的时空发展规律。为我国地面沉降防治规划的实施和软土地区地面沉降的预测和防控提供较现有理论更贴近实际、更为合理有效的计算理论和技术。

地下水开采等引起的地下水运移和大面积地面下沉已严重影响和制约了长三角等软土地区的城市建设和经济增长，堪称人为的环境地质灾害。但目前现有的地面沉降计算模型均不能充分考虑软土固有的非线性、结构性、流变性等复杂特性，难以合理准确地计算和预测地面沉降的发生和发展，因而不能对地面下沉这一环境地质灾害实现有效的防控。本项目结合深入的理论研究和室内外测试，对能考虑软土的非线性和结构性以及非达西渗流等复杂条件的地面沉降计算理论进行较全面细致的研究，推导了水位随时间下降时地面一维固结沉降解析解、随时间变化的加载和抽水共同作用下地面一维固结沉降解析解、第二类越流系统中结构性弱透水土层一维固结解析解、水位下降引发的软土层一维非线性固结解析解、水位下降引发的软土层一维非线性大应变固结解析解、水位下降引发的双层和多层结构性软土层一维固结解析解、单井降水引发的土层轴对称三维固结沉降解析解、竖向线抽水源作用下含水层—软土层系统轴对称固结解析解、有限区域降水引发的土层三维轴对称固结沉降解析解、水位非轴对称下降引发的软土层三维固结解析解，并基于耦合模型考虑土层的非线性等特性对抽水作用引起的固结沉降进行了数值分析。以这些解和数值分析结果为基础,详细分析了软土的非线性和结构性等复杂因素对软土地区地面沉降性状的影响, 揭示了地面沉降的时空发展规律。为我国地面沉降防治规划的实施和软土地区地面沉降的预测和防控提供了较现有理论更贴近实际、更为合理有效的计算理论和技术。