中文摘要：

以天津滨海新区地下工程涉及较多的9～18m深度海相软土为研究对象,采用应力应变控制式三轴剪切渗透试验仪,分别进行三轴固结不排水试验（CU）、三轴不固结不排水试验（UU）以及模拟基坑开挖卸荷的减p路径试验（DEP）,得到滨海软土在不同应力路径下的力学性状与初始固结状态有关。CU与UU试验应力与应变关系曲线呈硬化特征,CU试验孔隙水压力与应变关系呈先剪缩后剪胀的性质;DEP试验应力与应变关系曲线呈软化特征,在等应力控制条件下,孔隙水压力与应变关系呈剪胀性质,孔压为负。DEP试验对于总应力强度参数有影响,对有效应力强度参数影响较小。在滨海软土基坑支护设计中,选用CU试验参数进行计算,设计偏于安全。

英文摘要：

By studying the marine soft clay 9-18 m below the land surface,on which many underground projects are laid in the Tianjn Binhai New Area,the consolidated-undrained triaxial compression test（CU）,unconsolidated-undrained triaxial compression test（UU） and simulated pressure path tests（DEP） of excavation are carried out on the stress and strain controlled triaxial shear penetration apparatus.According to the experimental results,behaviors of soft soil under different stress paths are related to initial consolidation states.The stress-strain curves of CU and UU tests have hardening characteristics,pore water pressure and the strain of CU test exhibit property of contracting first and then dilating.The stress-strain curve of DEP test has softening characteristics,under constant stress controlled conditions the pore water pressure and the strain of DEP test has property of dilatancy and the pore pressure is negative.DEP test affects the total shear strength properties but has little influence on effective shear strength parameters.It is safe to use the soil shear strength properties of CU test in the design of foundation pit bracing of the Binhai New Area.