不同含水比贵阳原状红黏土CU三轴试验研究

Experimental study on CU triaxial test of undisturbed red claywith different water content ratio in Guiyang

为研究贵阳地区原状红黏土在CU三轴试验下的力学性质,采取原状土试样制备的方法,得到三种不同含水比的原状红黏土试样,进行CU三轴试验。试验得到了贵阳原状红黏土在不同围压、不同含水比下的应力-应变关系、破坏形式以及孔隙压力变化规律,采用Mohr-Coulomb准则和规范法得到抗剪强度指标且分析了含水比对抗剪强度指标的影响。研究结果表明:(1)贵阳原状红黏土的应力-应变关系、孔隙压力均出现“驼峰型”软化特性,且围压越低、含水比越低,软化现象越明显,但也有少部分试样表现出微弱的硬化特征;(2)CU三轴试验中,随含水比的减小、围压的增大,贵阳原状红黏土试样的破坏形态由剪切破坏转变为鼓状破坏;(3)抗剪强度指标与含水比呈线性趋势变化,其中内摩擦角与含水比呈正相关,黏聚力与含水比呈负相关。

In order to study the mechanical properties of undisturbed red clay in Guiyang area under CU triaxial test,by the method of undisturbed red clay sample preparation,three kinds of undisturbed red clay samples with different water content ratios are prepared with the CU triaxial test.In the CU triaxial test,the stress-strain relationship,failure mode and pore pressure variation of undisturbed red clay in Guiyang under different confining pressures and water content ratios are obtained.At the same time,by Mohr-Coulomb criterion and standard method,the shear strength index obtained on the shear strength index is analyzed.The results indicate that:(1)the stress-strain relationship and pore pressure of undisturbed red clay in Guiyang show hump-type softening characteristics,and the softening phenomenon is more obvious with lower confining pressure and lower water content ratio,but a few samples show weak hardening characteristics;(2)in CU triaxial test,with the decrease of water content ratio and the increase of confining pressure,the failure mode of undisturbed red clay in Guiyang changes from shear failure to drum failure;(3)the shear strength index and water content ratio changes linearly,and the internal friction angle is positively correlated with water content ratio,while the cohesion is negatively correlated with water content ratio.