以重庆武隆地区二叠系灰岩作为研究对象，通过三轴试验对该地区的灰岩屈服强度、峰值强度、残余强度与围压的关系进行了探讨。根据塑性力学的相关理论，将灰岩0～15MPa围压下的应力-应变曲线划分了孔隙压密、弹性、屈服、软化以及流塑5个变形阶段，提出了灰岩各阶段的力学模型。并且特别讨论了灰岩力学模型屈服和软化2个代表性阶段。在屈服阶段，利用主应变作为重要参数，结合Mises和Mohr-Coulomb屈服准则，建立了屈服阶段的非线性本构方程；在软化阶段，根据Mohr-Coulomb屈服准则和塑性软化理论，推导出了软化阶段的本构方程。结果表明，所建立的本构方程和试验结果相吻合，具有较高的准确性和实用性，可为类似的边坡稳定性研究提供重要的参考价值。

With the Permian limestone in Chongqing Wulong area as research object, the relations among yield strength, rock peak intensity, residual strength and confining pressure were studied through triaxial test. According to the plastic mechanics theory, the stress-strain curve under the 0-15MPa confining pressure of limestone can be divided into the following five phases: dense phase, elastic phase, yield phase, softening phase and flow plastic phase. Moreover, the mechanical model of each phase was proposed. In addition, yield phase and softening phase as two representative phases were discussed in depth. In yield phase, the nonlinear constitutive equation in yield phase was established with the principal strain as important parameter in association with Mises and Mohr-Coulomb yield rules. In softening phase, the constitutive equation in softening phase was deduced according to Mohr-Coulomb yield rules and plastic softening theory. Results of the constitutive equations were consistent with test results, which vindicated the accuracy and practicality of the models. These conclusions provide significant reference for similar slope stability researches.