基坑土体卸荷剪切模量真三轴试验研究

通过对基坑土体真三轴卸荷不排水试验结果的分析,研究了由广义虎克定律推导出的土体广义剪应力与广义剪应变的关系,并根据土体实际应力路径定义了中主应力系数,推导了基坑土体卸荷切线剪切模量计算公式。研究表明:土体广义剪应力与广义剪应变关系曲线呈明显的非线性,中主应力对土体强度的影响存在区间效应。在中主应力σ2的数值由σ3逐步增加到σ1的过程中,土体的强度逐步提高到一定峰值后,再逐步减小。

STUDY ON TRUE TRIAXIAL TEST OF EXCAVATION SOIL MASS OF UNLOADING SHEARING MODULUS

By analyzing dumping undrained true triaxial test of excavation soil mass, it is studied the relation between generalized shear stress and generalized shear strain derived by generalized Hook's law. Then intermediate principal stress coefficient is defined based on actual stress path and a shearing modulus' formula is also derived under plane unit elongation strain condition. The study results show that generalized shear stress has a strong nonlinear relation with generalized shear strain, and intermediate principal stress has interval effect on soil strength. The strength of soil enhances to a certain peak value gradually and diminishes gradually in the process of intermediate principal stress σ2 increases from σ3 to σ1.