常规三轴试验固结阶段的理论研究及试验验证

THEORETICAL RESEARCH AND EXPERIMENTAL VERIFICATION ON CONSOLIDATION STAGE OF CONVENTIONAL TRIAXIAL COMPRESSION TEST

常规三轴试验的固结阶段属于球应力作用下的三维压缩而渗流只发生在竖向的特殊过程,与Terzaghi一维固结过程既有区别又有一定的共同点,因此不能直接用Terzaghi一维固结理论解决该问题。基于有效应力原理、Darcy定律和线性材料假设,建立常规三轴试验固结阶段的水压力消散理论方程,并进一步给出其分离变量法的幂级数解和有限元解答。算例分析表明,幂级数解在固结初期收敛性较差,只有当固结度稍大时才表现出良好的稳定性。将理论方程的计算结果与双压力室WF有效应力路径三轴试验结果比对后发现,理论方程能够揭示三轴试验固结阶段的主要特点。理论分析表明,其差异性主要在于理想假设与真实土样性质不完全相同这一客观存在。

The consolidation process of the conventional triaxial compression test is a three-dimensional compression under the action of spheric stress while seepage occurs only in the vertical direction, which has differences and some similarities with the process of Terzaghi＇ s one-dimensional consolidation. Therefore, Terzaghi＇ s one-dimensional consolidation theory can＇ t be used directly to solve the problem. Based on the effective stress principle, Darcy＇ s law and the assumption of linear material, a water pressure dissipation theory equation was set up for consolidation stage of conventional triaxial compression test, and the corresponding power series solution derived from the method of separation of variables and the finite element solution were provided. The example analysis showed that the solution of power series had poor astringency in the early stage of consolidation but good stability when the degree of consolidation is slightly larger. A comparison of the calculation results of the theoretical equation with test results of the double pressure chamber effective stress path triaxial compression test indicated that the theoretical equation could reveal the main characteristics of the consolidation stage of triaxial test. Theoretical analysis showed that, the difference lay mainly in the objective existence that ideal assumption and real soil properties were not exactly uniform.