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通过在室内进行膨胀土的常规直剪和干湿循环试验,探讨了低应力条件下膨胀土的黏聚力随循环次数、循环幅度的变化规律;运用损伤力学的研究方法,基于剩余黏聚力定义损伤变量,据此建立了反映循环次数和循环幅度变化的非线性疲劳损伤模型。研究结果表明:在相同循环幅度和初始控制含水率下,膨胀土的剩余黏聚力随循环次数的增加而衰减;在相同循环次数和初始控制含水率下,膨胀土的剩余黏聚力随循环幅度的增加而衰减;利用室内简单试验建立的非线性疲劳损伤模型可以用来计算干湿循环作用下膨胀土的损伤度。
Through the conventional direct shear test and wet-dry cycle test of expansive soils in the interior, the cohesive force of expansive soils under low stress is studied. The variation rules of cohesive strength and cyclic amplitude of expansive soils are investigated. Based on the research methods of damage mechanics and residual cohesion The damage variables are defined, and then a nonlinear fatigue damage model is established to reflect the variation of cycle number and cycle amplitude. The results show that the residual cohesion of the expansive soil decreases with the increase of the number of cycles under the same cyclic amplitude and initial controlled moisture content. The residual cohesion of the expansive soil with the same number of cycles and initial control of the water content decreases with the cycle The amplitude of which increases and decays. The non-linear fatigue damage model established by a simple indoor test can be used to calculate the damage degree of expansive soil under the action of the wetting-drying cycle.