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利用FSY30型应变控制式非饱和土三轴仪采用常含水率试验,研究陕西泾阳县某边坡原状黄土在不同含水率(无偏应力条件下增湿)、不同固结围压下的强度和变形特性,求得Fredlund双应力状态变量抗剪强度公式中b?值并利用含水率建立了工程中实用的抗剪强度公式;再将天然原状土在不同偏应力水平下增湿饱和后继续剪切,观察其力学特性。两种增湿条件下试验结果表明:该地区黄土应力应变曲线关系呈剪切硬化型;含水率与初始基质吸力呈双曲线关系,剪切过程中基质吸力无明显变化,抗剪强度指标黏聚力随着含水率的增大显著降低而内摩擦角所受影响较小;有偏应力条件下试样浸水饱和后破坏强度显著降低,但对应力应变关系影响较小,增湿时偏应力水平越低,土样饱和后的稳定偏应力值越小。
Based on the experiment of constant moisture content of strain-control unsaturated soil triaxial apparatus of FSY30, this paper studies the strength and stability of undisturbed loess of a slope in Jingyang County of Shaanxi Province under different moisture content (without humidification under unbiased stress) and Deformation characteristics of Fredlund shear stress in the formula to obtain b? Value and the use of water content in the project to establish a practical formula for shear strength; then the natural undisturbed soil at different partial stress levels under the humidification saturation shear Cut, observe the mechanical properties. The test results under two humidification conditions show that the stress-strain curve of loess in this area shows a shear hardening type, the water content is in hyperbolic relationship with the initial substrate suction, and there is no obvious change in the substrate suction during shearing. The shearing strength index cohesion The force decreases with the increase of water content and the influence of internal friction angle is small. Under the condition of deviatoric stress, the failure strength of the sample decreases obviously after saturated with water, but it has little effect on the relationship between stress and strain. The lower the value of stable deviatoric stress after saturated soil sample.