To study the creep property of salt rock, uniaxial compression creep tests on salt rock specimens were carried out. The test results indicate that there is no steady creep of the salt rock used in this test in a strict sense. Even in the steady creep stage, the creep rate of salt rock changes continuously over time, but with a relatively smaller change range. When the axial stress does not exceed 9.5 MPa, the isochronous stress–strain curve of salt rock is approximately straight. While the axial stress exceeds 9.5 MPa, the isochronous stress–strain curve deflects to the strain axis, and the larger the axial stress, the more obvious the deflection. Thus, the long-term strength of the salt rock used in this test can be determined as 9.5 MPa. A mathematical expression for predicting the creep failure time of rock is proposed on the basis of assuming the change rule of rock strength over time conforms to the Usher function. Then starting from the variation in deformation modulus with respect to time in the creep process of salt rock, the elastic modulus of the damaged rock material is characterized by the deformation modulus, and the creep damage evolution equation of rock is established. Combined with the continuous damage mechanics theory, a new creep damage constitutive model for rock is proposed. The rationality of the model is verified using the uniaxial compression creep test results of salt rock. The results show that the new model can not only describe the attenuation and the steady creep of salt rock under low stress level, but also reflect the whole creep failure process under high stress level. The predicted curves under different axial stresses are all in good agreement with the test data.

中文翻译：

---

盐岩单轴压缩蠕变特性及损伤本构模型

为研究盐岩的蠕变特性，对盐岩试件进行了单轴压缩蠕变试验。试验结果表明，本试验所用盐岩没有严格意义上的稳定蠕变。即使在稳定蠕变阶段，盐岩蠕变速率也随时间不断变化，但变化幅度相对较小。当轴向应力不超过9.5 MPa时，盐岩等时应力-应变曲线近似直线。当轴向应力超过9.5 MPa时，等时应力-应变曲线向应变轴偏斜，轴向应力越大，偏斜越明显。因此，本次试验所用盐岩的长期强度可确定为9.5 MPa。在假设岩石强度随时间的变化规律符合Usher函数的基础上，提出了预测岩石蠕变破坏时间的数学表达式。然后从盐岩蠕变过程中变形模量随时间的变化出发，用变形模量表征损伤岩石材料的弹性模量，建立岩石蠕变损伤演化方程。结合连续损伤力学理论，提出了一种新的岩石蠕变损伤本构模型。通过盐岩单轴压缩蠕变试验结果验证了模型的合理性。结果表明，新模型不仅可以描述低应力水平下盐岩的衰减和稳态蠕变，也反映了高应力水平下的整个蠕变破坏过程。不同轴向应力下的预测曲线均与试验数据吻合较好。