贵阳红黏土的应力-应变软化模型及参数研究

通过对不同含水量和不同围压下的贵阳红黏土进行三轴固结不排水试验,系统地研究了贵阳红黏土的软化特性及孔隙水压力的变化规律。试验结果表明:贵阳红黏土破坏形态具有明显的剪切带;应力-应变曲线出现了带有驼峰的应变软化现象,固结过程中孔隙水压力与时间呈指数函数关系,剪切过程中孔隙水压力与轴向应变呈双曲线型。研究认为,土体的结构屈服应力和固结不排水试验中产生的孔隙水压力是造成贵阳红黏土软化的主要因素。根据沈珠江、张尔齐等人的软化模型,对贵阳红黏土进行拟合,求解模型参数及置信区间,为贵阳红黏土进一步的数学模型建立提供理论基础。

Research of the Stress-strain Softening Model and Parameters of Red Clay in Guiyang

The softening characteristics and change law of pore pressure of Guiyang red clay were systematically studied using the laboratory tests such as consolidated undrained triaxial tests on the undisturbed red clay sampled from different water and confining pressure. The results indicated that the destruction morphology showed the shear band obviously; softening with hump appeared in the stress-strain curve; pore pressure-time curve was exponential function relationship under consolidation process; pore pressure- strain curve was hyperbola under shear process. The studies indicate that the main factors of softening were structure yield stress of the soil and pore pressure in consolidated undrained triaxial tests. Model parameters were fitted and and confidence intervals were solved using softening model by Shen Zhujiang and Zhang Erqi. It provides a theoretical basis for the further mathematical model establishment of Guiyang red clay.