高压下饱和黏土B系数研究

为了对高压与常压固结后饱和黏土B系数之间存在差异性与否,及其影响因素展开研究,利用GDS三轴试验机开展了固结压力为2 MPa的饱和黏土等向固结试验,其中特别设计进行了高压固结前后的B系数检测试验。试验结果表明:"饱和"黏土高压固结B系数明显小于1的原因在于试样无法达到饱和度100%的理想饱和状态,而并非先前研究报道的高压固结后黏土样内孔隙水以物理性质明显不同于自由水的结合水为主。另外,饱和黏土高压固结过程中,孔压完全消散明显滞后于常规体积变形–时间对数曲线上主固结完成点的出现;高压固结后饱和黏土B系数达到稳定的时间明显长于常压相应值。

Coefficient B of saturated clay under high pressure

In order to make an investigation into the possible difference in coefficient B of saturated clay under high and normal pressures and the relevant contributory factors, isotropic consolidation tests on saturated clay under pressures of 2 MPa are conducted by GDS triaxial apparatus, and a novel test procedure is designed to check coefficient B before and after consolidation. The test results indicate that the reason for unusually small coefficient B of “saturated” clay after high-pressure consolidation is that the soil sample cannot reach 100% ideal saturation, rather than, as reported previously, the majority of the pore water in high pressure consolidation sample being bound water whose physical characteristics obviously differ from those of bulk water. In addition, the complete dissipation of the pore water pressure significantly lags behind the end of the primary consolidation in volume-logarithmic time curve during high pressure consolidation tests on saturated clay, and the process of coefficient B of consolidated clay under high pressure getting to be stable takes much longer time than that under normal pressure.