天津市区第一海相层粉质黏土卸荷路径下强度特性的试验研究

Experimental studies of unloading mechanical properties of silty clay of first marine layer in Tianjin city

土的强度特性与土体中应力变化过程、固结状态有关,常规的三轴试验并不能真实地反映土体经历的应力路径对其强度特性的影响。采用自制的应力-应变联合控制式三轴试验仪,对天津市区地层中第一海相层的粉质黏土原状饱和试样进行一系列特殊三轴试验,研究了排水卸荷条件对其强度特性的影响。试验结果表明:经历排水卸荷路径的土体的加荷剪切总应力强度指标大于常规试验结果,也大于前人在不排水卸荷路径下的试验结果,但几种应力路径下土体的有效应力强度指标基本相等。研究成果对天津市区基坑开挖及支护结构设计计算、软土隧道施工研究及其他相关岩土工程问题的研究均有较大的实用价值。

Shear strength properties of clay are related to stress variation and consolidation state. By using the conventional triaxial shear test, the effect of stress paths on it can not be reflected actually. With the self-made triaxial equipment, a series of special shear tests has been carried out to study the effect of drained and unloading stress paths on shear strength properties of a typical soil in Tianjin city. It is shown that the total shear strength properties are different from that of conventional triaxial test. And the total shear strength properties under drained and unloading stress paths are different from the experimental results under undrained and unloading stress paths. And the effective shear strength properties under different stress paths are equal.