针对传统西原模型不能描述岩石加速蠕变特性的问题，根据辽宁阜新海棠山隧道出现的围岩流变现象，通过现场取样，采用MTS-812.02岩石试验加载系统对砂岩进行不同围压和不同应力水平下的三轴蠕变试验，分析其蠕变特性。在传统西原模型的基础上，考虑了岩石进入加速蠕变阶段的判别条件，串联一个加速蠕变触发的元件，通过损伤定义流变参数的非定常性，建立了一个以屈服强度和长期强度为判别条件新型非定常蠕变模型，并将一维推广至三维；结合砂岩蠕变试验结果，对砂岩流变试验全过程曲线进行模型参数拟合，结果表明：建立的新型砂岩非定常蠕变模型与试验结果具有较高的拟合度，该模型克服了传统西原模型难以描述加速蠕变阶段的缺陷，不仅能够反映出砂岩瞬时应变、稳定蠕变和亚稳定蠕变阶段的流变特性，还能很好地描述了砂岩加速蠕变阶段的流变特性。最后，通过对砂岩流变参数的反演，得到了砂岩的损伤演化方程，结合现场围岩应变监测数据对模型参数进行拟合，很好地反映了流变参数损伤劣化规律。研究成果为研究岩体流变的非线性问题和确保工程安全提供了新思路。

In view of the problem that the traditional Nishihara model can not describe the accelerated creep characteristics of rock, according to the rheological phenomenon of surrounding rock in Haitangshan tunnel, Fuxin, Liaoning Province, this paper analyzes the creep characteristics of sandstone by triaxial creep tests under different confining pressures and different stress levels with MTS-812.02 rock test loading system. On the basis of the traditional Nishihara model, the discriminant conditions for the rock to enter the accelerated creep stage are considered, and a trigger element for accelerated creep is connected in series. The unsteadiness of rheological parameters was defined by damage and a new unsteady creep model based on yield strength and long-term strength was established, which was extended from one dimension to three dimension. Combined with the creep test results of sandstone, the rheological model parameters of sandstone were fitted. The results show that the new unsteady creep model of sandstone was in good agreement with the test results. This model overcomes the defect that the traditional Nishihara model is difficult to describe the accelerated creep stage. It can not only reflect the rheological properties of sandstone at the stage of instantaneous strain, stable creep and metastable creep, but also well describe the rheological properties of sandstone at the stage of accelerated creep. Finally, through the inversion of rheological parameters, the damage evolution equation of sandstone is obtained. Combined with the field surrounding rock strain monitoring data, the model parameters are fitted, which well reflects the damage deterioration law of rheological parameters. The research results of this paper provide a new idea for studying the nonlinear problem of rock mass rheology and ensuring engineering safety.