上海地区软土旁压加卸载变形特性试验研究  

Experimental researches on in-situ loading and unloading deformation characteristics of soft soil based on pressuremeter tests in Shanghai area

作　　者：张晗 杨石飞 王琳 林天翔 ZHANG Han;YANG Shi-fei;WANG Lin;LIN Tian-xiang(Postdoctoral Programme,SGIDI Engineering Consulting(Group)Co.,Ltd.,Shanghai 200093,China;Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;Department of Civil Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Shanghai Engineering Research Centre of Geotechnical Test for Underground Space,Shanghai 200093,China)

机构地区：[1]上海勘察设计研究院(集团)有限公司博士后科研工作站,上海200093 [2]同济大学地下建筑与工程系,上海200092 [3]上海交通大学土木工程系,上海200240 [4]上海岩土与地下空间综合测试工程技术研究中心,上海200093

出　　处：《岩土工程学报》2022年第4期769-777,F0003,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金青年基金项目(42002272);上海市“超级博士后”激励计划项目(2019327)。

摘　　要：软土具有强度低、压缩性高的特点,在不同应力状态、应力路径下其变形呈现明显不同的非线性特征,研究软土的原位变形特性对各类地下工程土体变形的控制具有重要意义。通过对上海地区不同深度土体进行原位旁压加卸载试验,从加载及卸载两个维度对原位土体的变形特性进行描述。通过旁压加载试验结合室内小应变三轴试验,获取了土体剪切模量G随剪应变γ的变化规律;通过旁压卸载试验研究软土原位卸荷回弹变形特性,探讨了各层土不同卸载前载荷水平及卸载等级下,土体模量比E;与卸载比R之间的内在关系。研究结果揭示了软土在加载情况下的刚度衰减规律及卸荷条件下影响刚度特性的关键因素,为控制地下空间开发中的土体变形问题提供借鉴。The quality of the soft soil includes low strength and high compressibility,and the deformation shows obviously different nonlinear characteristics under different stress states and paths.It is of great significance to study the in-situ deformation characteristics of soft soil for controlling the deformation in various underground projects.In this study,such deformation characteristics are well described from two aspects of loading and unloading through PMT in Shanghai area.The relationship between shear modulus G and shear strainγis obtained by the pressuremeter loading tests combined with laboratory small-strain tests.At the same time,the internal relationship between modulus ratio Ev and unloading ratio R is studied under different maximal unloading pressures and unloading levels by the pressuremeter unloading tests.The results reveal the stiffness degradation law for loading tests and the key factors determining the stiffness characteristics for unloading tests,which will provide the relevant reference for controlling soil deformation in the development of underground space.

关 键 词：软土 旁压加卸载试验 刚度衰减 卸载等级 卸载前载荷水平 

分 类 号：TU433[建筑科学—岩土工程]