赣南花岗岩残积土的抗剪强度及其影响因素

Influencing Factors of Shear Strength of Granite Residual Soil in Southern Jiangxi Province

为研究赣南花岗岩残积土抗剪强度影响因素,采用X射线粉晶衍射和扫描电镜等方法对赣南地区的黑云母二长花岗岩残积土和黑云母花岗岩残积土的矿物成分及微观结构进行了分析,并通过三轴固结不排水剪切试验对2类花岗岩残积土的原状样与重塑样的抗剪强度进行了研究。结果表明:赣南花岗岩残积土矿物成分主要为石英矿物和高岭石、伊利石等黏土矿物,原生结构强度明显,原状样的抗剪强度高于重塑样;各围压下原状样和重塑样的应力-应变关系均呈应变-硬化型,表现为塑性破坏;受孔隙度大和粗颗粒多的影响,孔压-应变关系在低围压下表现为先剪缩后剪胀,在高围压下始终表现为剪缩;其内摩擦角受粗颗粒含量影响明显,黏聚力受细颗粒含量影响明显。

In order to study the influence factors of shear strength of granite residual soil in southern Jiangxi Province,X-ray powder diffraction and scanning electron microscopy were used to analysis the mineral composition and microstructure of biotite monzonitic granite residual soil and biotite granite residual soil in southern Jiangxi Province.Through triaxial consolidation undrained shear tests,the shear strength of undisturbed and remolded samples of two types of granite residual soils was also studied.The results show that the mineral compositions of granite residual soil in southern Jiangxi Province are mainly quartz minerals and clay minerals such as kaolinite and illite.The primary structural strength is obvious,and the shear strength of undisturbed sample is higher than that of remolded sample.The stress-strain relationship of undisturbed sample and remolded sample under various confining pressures is strain-hardening,which shows plastic failure;And the pore pressure-strain relationship is affected by large porosity and large coarse grains.Under low confining pressure,the relationship is first shear contraction and then shear dilatation,and always shear contraction under high confining pressure.The internal friction angle is obviously affected by the content of coarse particles,and the cohesion is obviously affected by the content of fine particles.