排水条件对粗粒土强度和变形影响的试验研究

Experimental study on the influence of drainage conditions on the strength and deformation of coarse-grained soil

为分析排水条件对粗粒土力学性质的影响,设计固结排水(CD)与固结不排水(CU)三轴试验,分析排水条件对土体强度和变形的力学响应机理。研究结果表明,不同排水条件下土样剪切变形均呈现出应变硬化特征,轴向应变小于6%,剪应力显著增大,轴向应变大于6%,剪应力缓慢增加。固结不排水试验土样孔隙水压力在轴向应变2%时迅速增大至峰值,随剪切变形发展其略有下降且保持相对稳定。固结排水试验土样均呈现先剪缩后剪胀的特征,剪胀相变点随围压增大相对滞后出现。固结排水剪切土样黏聚力大于固结不排水剪切土样,两者内摩擦角相比变化不大,排水条件是影响粗粒土强度特性的重要因素。

In order to analyze the influence of drainage conditions on the mechanical properties of coarse-grained soil,consolidated drained(CD)and consolidated undrained(CU)triaxial tests are designed to analyze the mechanical response mechanism of drainage conditions on soil strength and deformation.The results show that the shear deformation of soil under different drainage conditions shows the characteristics of strain hardening.The axial strain is less than 6%,the shear stress increases significantly,the axial strain is more than 6%,and the shear stress increases slowly.The porewater pressure of consolidated undrained test soil sample increases rapidly to the peak value when the axial strain is 2%,and decreases slightly with the development of shear deformation and remains relatively stable.The consolidation drainage test soil samples show the characteristics of shear shrinkage first and then shear dilatancy.The phase transition point of shear dilatancy appears relatively late with the increase of confining pressure.The cohesion of consolidated drained shear soil sample is greater than that of consolidated undrained shear soil sample,and the internal friction angle has little change.The drainage condition is an important factor affecting the strength characteristics of coarse-grained soil.