K_0固结粉质黏土非共轴特性试验研究

Experimental study on non-coaxial characteristics of K_0 consolidation saturated silty clay

为研究主应力轴定向旋转条件下K_0固结饱和粉质黏土的强度特性和变形特性,利用GDS三轴试验系统,进行K_0固结饱和粉质黏土三轴定向剪切试验,研究不同大主应力方向角β时K_0固结饱和粉质黏土的应力–应变发展规律及应力–应变非共轴现象。结果表明:当β<45°时,K_0固结粉质黏土表现为轴向压缩变形为主,其抗剪强度随着β的增大而增加;当β=45°时,试验变形以扭剪变形为主;当β>45°时,试样轴向由剪缩变形转换为剪胀变形,径向和环向表现为挤缩变形,其抗剪强度随着β的增大而减小,土体抗剪强度最大值出现在β=60°时,而非纯扭剪试验β=45°时。K_0固结粉质黏土在τ_(zθ)/σ_(c0)-(σ_z-σ_θ)/(2σ_(c0))平面上强度包络线近似呈抛物线形。除纯扭剪试验外,其余组试验结果表明K_0固结粉质黏土应力–应变关系表现出明显的非共轴现象。上述研究成果为复杂应力路径条件下K_0固结饱和粉质黏土的力学特性及其本构关系研究提供了科学依据。

To research the strength and deformation characteristics of K0 consolidation saturated silty clay under principal stress axis rotation conditions,a series of directional shear triaxial tests were carried out by using the GDS triaxial test system. The stress vs. strain development law and non-coaxial phenomenon of K0 saturated silty clay under different principal stress direction angle was researched. The results show that the deformation of K0 consolidation saturated silty clay mainly performs as the axial compression deformation and its shear strength increases with the principal stress direction angle increasing when β is smaller than 45°. The deformation performs as torsional shear deformation when β is equal to 45°. The axial deformation performs as the dilatancy deformation and the radial deformation performs as the extrusion shrinkage deformation when β is larger than 45°And its shear strength decreases with the principal stress direction angle increasing. The maximum shear strength of soil appears at β equals to 60° but not at the pure torsion shear test which β equals to 45°. The strength envelope performs as parabola types on the τ（zθ）/σ（c0）-（σz-σθ）/（2σ（c0）） plan. Test results show that the stress vs. strain curves of K0 consolidated silty clay obviously performs as non-coaxial phenomenon except for the pure torsional shear test. The above results provide a scientific reference to research the mechanics and constitutive relation of the K0 consolidation saturated silty clay under the complex stress path.