侧向卸荷条件下上海灰色粘性土的三轴试验研究

摘要:

本文通过K0固结条件下GDS常规三轴和侧向卸荷三轴试验分析了应力路径对上海地区⑤1层灰色粘性土的强度与变形特性影响。试验结果表明不同围压条件下侧向卸荷三轴试验有效应力路径基本呈倒“L”形,而常规三轴试验则呈“S”形。侧向卸荷三轴试验的负孔压数值随围压减小而单调增加,其最终值与围压大小正相关；侧向卸荷三轴压缩试验应力应变关系与常规三轴压缩试验有较多相似,其峰值强度都随体积应力的增加而提高,但破坏时应变值明显较常规压缩试验偏低。归一化土体模量与应力水平呈幂次关系,其幂指数m值与《上海市基坑工程技术标准》中对浅层土建议值基本相同。

Abstract:

This paper analyzes the influence of stress path on the strength and deformation characteristics of grey cohesive soil of layer ⑤1 in Shanghai area by GDS conventional triaxial test and lateral unloading triaxial test under K0 consolidation condition. The test results show that the effective stress path of lateral unloading triaxial test is basically inverted "L" shape under different confining pressure conditions, while that of conventional triaxial test is "s" shape. The negative pore pressure of triaxial test with lateral unloading increases monotonically with the decrease of confining pressure, and its final value is positively correlated with the confining pressure; The stress-strain relationship of lateral unloading triaxial compression test is more similar to that of conventional triaxial compression test. Its peak strength increases with the increase of volume stress, but the strain value at failure is obviously lower than that of conventional compression test. the normalized soil modulus has a power relationship with the stress level, and the power index m value is basically the same as that of shallow soil advised by Shanghai Technical Code for Excavation Engineering.