贵阳红黏土变形及强度特性试验研究

摘要

对不同含水率的贵阳原状红黏土进行了一系列不固结不排水(UU)、固结不排水(CU)、固结排水(CD)试验,分析了3种试验条件下红黏土的变形及抗剪强度特性.结果表明:3种试验条件下应力-应变关系表现出驼峰型应变软化特性,且含水率越低软化现象越明显;不排水条件得出的抗剪强度指标c值较大、φ值较小,排水试验相反;随含水率增大,抗剪强度指标呈阶段性降低,且对c值的影响要大于φ值;同等试验条件下,红黏土强度指标普遍高于一般黏土.研究认为,贵阳红黏土在变形及强度方面表现出的一系列特性,主要与游离氧化铁胶结物形成的超固结性和粒间结合水的水胶连接键的形成和断裂有关.%The deformation and shearing strength characteristics of Guiyang original red clay are analyzed by three tests including unconsolidation-undrained (UU) test,consolidation-undrained (CU) test and consolidation-drainage (CD) test.The results show that the stress-strain relationship is a softening hump-like curve among these tests.And the softening is more obvious in lower moisture content.There are higher cohesion (c) and lower inner friction angle (φ) in undrained triaxial tests,the result of drainage experiment is opposite.With the increase of water content,shear strength parameters are reduced unevenly,and the impact of c value is greater than the value of φ.The shear strength index of the red clay is generally higher than other clay in the same test conditions.The study shows that the characteristics of Guiyang red clay in deformation and shear strength are mainly connected with the over-consolidated features of free iron oxide and the formation or fracture of water glue connection of combined water within the particles.