为研究低应力下软岩的损伤特性及应力−应变全过程情况，基于损伤力学理论，考虑损伤阈值对岩石弹性阶段的影响，将轴向应变作为岩石的损伤变量因子，结合Drucker-Prager强度准则与胡克定律，构建了1个软岩损伤阈值表达式，同时引入残余剪切强度，完整性地描述其变形特征。采用Weibull分布理论及Lemaitre应变等价理论，构建1种能同时反映低应力下线弹性阶段和残余变形阶段的软岩损伤本构模型。通过应力应变曲线特征点及岩石三轴压缩试验数据计算出理论模型参数，并用指数函数对峰值强度、残余剪切强度与围压之间的非线性变化规律进行合理的描述。最终结合煤岩试验结果，验证了本研究所提理论模型的合理性与适用性。

In order to study the damage characteristics and the whole stress-strain process of soft rock under low stress, based on the damage mechanics theory and considering the impact of damage threshold on the elastic stage of rock, a damage threshold expression of soft rock was constructed by taking axial strain as the damage variable factor of rock and combining Drucker-Prager strength criterion and Hooke’s law. At the same time, the residual shear strength is introduced to describe the deformation characteristics completely. Based on Weibull distribution theory and Lemaitre strain equivalence theory, a damage constitutive model of soft rock is constructed which can reflect both the elastic stage and the residual deformation stage of low stress downline. The parameters of the theoretical model are calculated by the characteristic points of the stress-strain curve and the data of rock triaxial compression test. The nonlinear variation of peak strength, residual shear strength and confining pressure is reasonably described by exponential function. Finally, the rationality and applicability of the theoretical model proposed in this study are verified by the coal and rock test results.