裂隙性黄土单轴抗压试验研究

An experimental study of the uniaxial compressive strength of fractured loess

黄土中裂隙属黄土体结构面,影响黄土的强度特性,对工程的稳定和安全产生重要影响。以临潼地区Q2黄土为研究对象,开展了裂隙性黄土无侧限抗压强度试验,探讨了不同裂隙倾角对裂隙性黄土强度特性的影响规律。试验结果表明:单轴受压条件下,不同裂隙倾角的裂隙性黄土破坏模式主要有压裂破坏、压剪破坏和滑移-压剪复合破坏三种类型,且裂隙性黄土试样破裂面的形成受裂隙倾角的控制。裂隙倾角变化对裂隙性黄土的应力-应变曲线影响显著,裂隙倾角为0°~30°和90°时,裂隙性黄土的应力-应变曲线可分为裂隙压密阶段、弹性变形阶段、塑性屈服阶段以及残余阶段等;而裂隙倾角为40°~70°,裂隙性黄土的应力-应变曲线无明显的4个阶段,且破坏是突发性的。随裂隙倾角的增大,裂隙性黄土单轴抗压强度曲线整体表现为先降低后增大的"V"形。显著体现裂隙倾角变化对裂隙性黄土试样单轴抗压强度的影响,同时,裂隙倾角对裂隙性黄土抗剪强度也具有显著的控制效应。

Fissures in loess belong to the structural planes and has an important influence on the stability and safety of practical projects. The Lintong Q2 loess is taken as research objects in this paper and uniaxial compression tests are conducted to investigate the relationship between the fractured loess compressive strength and the fracture angles. The results indicate that the failure modes of the fractured loess mainly includes fracturing failure,compressive-shear failure and slip-compression-shear failure,and the formation of fracture surfaces of the fractured loess is controlled by the fracture angles. Change in the fracture angles has a significant effect on the stress-strain curve for the fractured loess. When the fracture angles of fractured loess are changed between 0° and 30°,the stress-strain curve of the fractured loess are divided into the compressive densification stage,the linear elastic stage,the plastic yield stage and the residual stage,so are the fracture angles of 90°. There are not four stages as the fracture angles change between 40° and 70°,and the failures of the fractured loess are sudden. With the increasing fracture angles,the uniaxial compressive strength of the fractured loess firstly decreases and then increases with the V shape,which significantly shows the effect offracture angles on the uniaxial compressive strength of the fractured loess. Meanwhile,the fracture angles have a remarkable control effect on the shear strength of the fractured loess.