深基坑降水作用下远场土层变形机理研究

项目名称： 深基坑降水作用下远场土层变形机理研究

项目编号： No.41472250

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 地质学

项目作者： 夏小和

作者单位： 上海交通大学

项目金额： 103万元

中文摘要： 大规模岩土工程活动已成为城市地面沉降的重要诱因，复杂地质条件下深基坑工程大面积降排水对地面沉降的加速作用日益突出。基坑临时性降水的渗流变形不同步和止水帷幕的遮拦效应导致土层流固耦合作用复杂化，使得地面沉降的预测和控制更为困难。本项目针对深基坑引起的工程性地面沉降问题，采用模型试验、现场测试和数值分析等方法研究基坑降水引起的远场土层变形机理及分析方法。在研制室内降水模拟试验系统的基础上，通过模型试验研究组合土层试样在减压降水作用下的变形响应特征，确定合理的本构模型和参数；研究基于流固耦合理论的降排水数值模拟方法，结合模型试验和现场测试，探讨不同地层结构和止水形式下降排水的环境效应及其影响规律，揭示基坑降水过程中远场土层受力变形和渗流响应机理，建立土层变形预测方法。研究成果对于阐明基坑降排水引起地面沉降灾害及其控制机理具有重要意义，将为深基坑减压降水引发地面沉降的防治措施研究提供理论基础。

中文关键词： 降水；工程地质；流固耦合；地面沉降；土层变形

英文摘要： Large-scale geotechnical engineering activities have become one of the most significant causes of land subsidence in urban area, and accelerating effect of ground settlement induced by large area dewatering of deep excavation is increasingly prominent under the complicated geological condition. Furthermore, both the desynchrony of the seepage and soil deformation during temporary dewatering and the cutoff effect of the excavation retaining structures will make the soil-water coupling effect be more complex, which increases the difficulty to predict the ground surface settlement and to control the land subsidence in urban area. In order to evaluate the land subsidence caused by the deep excavation, the mechanism and analysis method of dewatering-induced soil deformation will be investigated in this project by using model tests, field monitoring and numerical analysis. Firstly, experiment devices and relevant monitoring system for laboratory dewatering simulations are developed, and lab model tests are conducted to study the deformation responses of soil layers using the proposed testing system. With the obtained test results, a suitable constitutive model is obtained by improving the small strain constitutive model and the corresponding parameters are determined with the laboratory test results. Secondly, numerical analysis methods are studied based on the soil-water coupling theory and the developed constitutive model. Based on the proposed numerical method and the results of laboratory model tests and field monitoring, parametric studies, including different stratum structures and different forms of excavation retaining structure, are carried out to investigate the effects and influences laws of dewatering on surrounding environment. Finally, deformation mechanism of soil layers during the dewatering in deep excavation is revealed and a method used to predict dewatering-induced soil deformation is established based on the above results. The findings in this research are significant to illustrate the disaster mechanism of land subsidence due to dewatering in deep excavations and provide basic theories for studying the control measures of the land subsidence caused by deep excavations.

英文关键词： dewatering;engineering geology;soil-water coupling;ground settlement;soil deformation