不同应力路径下上海地区软黏土三轴试验研究

Triaxial Test of Soft Clay in Shanghai under Different Stress Paths

摘要:

在深基坑工程中，土体的开挖是个逐渐卸荷的过程。在这一过程中，土体的应力状态不断变化。为考虑应力路径对土体的影响，采用GDS三轴仪对上海深邃工程的原状软黏土进行三轴试验，研究不同应力路径下土体的应力-应变关系、孔隙水压力变化规律、有效应力路径和变形特性。结果显示：土的峰值强度、孔压、有效应力路径和变形等特性均受到应力路径的显著影响，在实际工程中应考虑这一因素。另外，需特别注意开挖卸荷过程中较小的变形就可能导致的破坏，应防范骤然破坏情况的出现。

Abstract:

The excavation of soil in deep foundation pit is an unloading process, in which the stress state of soil changes constantly. In order to consider the effect of stress path on soil, the undisturbed soft clay of Shanghai deep tunnel project was tested by GDS triaxial apparatus under different stress paths. The stress-strain relationship, pore water pressure variation law, effective stress path and deformation characteristics of soil under different stress paths were analyzed. The results show that the stress path has great influence on the characteristics of soil such as peak strength, pore pressure, effective stress path and sample deformation, which should be considered in engineering. Moreover, special attention should be paid to the possibility of damage when excavating and unloading, even if the deformation is small. Sudden damage should be prevented.