扭剪与三轴试验中孔压不均匀性的研究

Non-uniform Distribution of the Pore Water Pressure in Torsional and Triaxial Shear Tests

本文首先从理论上详细探讨了扭剪和三轴试验中孔压沿试样高度不均匀分布的现象和原因。再根据实验研究结果及理论推证,对动载周期为8秒的粉土试样得出结论:三轴试验中出现孔压不均匀的临界双幅轴应变是0.15%,扭剪试验中出现孔压不均匀的临界双幅剪应变是5.2%,因此,对粉土的三轴试验结果最好进行孔压不均匀性的校正,或量测试样中心孔压,而对扭剪试验则可直接在试样底部量测孔压。

The phenomenon and cause of non-uniform distribution of pore water pressure in the torsional and triaxial shear tests are theoretically discussed in detail at first.According to the laboratorial studying and theoretical inferring, we then concluded that the critical axial strain in the triaxial shear tests is 0.15% and the criticnl shear strain in the torsional shear tests is 5.2% if the silt samples are subjected to a cyclic loading with the period of 8 second. Therefore, in the triaxial shear tests, we had better measure the pore water pressure at the center of silt samples, or rectify the pore water pressure measured at the basement. But in the torsional shear tests, it is feasible to measure the pore water pressure directly at the basement of the samples.