不同加载路径下盐岩蠕变特性试验

为了研究加载路径对盐岩蠕变特性的影响，利用RLW-2000岩石流变试验机对盐岩试件进行了3种不同加载路径的蠕变试验，分析了盐岩在不同加载路径下的蠕变变形规律。结果表明，在恒围压、分级增加轴压加载路径下，随着轴向应力增加，盐岩瞬时应变、蠕变应变和蠕变速率均逐渐增大，衰减蠕变阶段持续的时间也逐渐延长；在恒轴压、分级卸围压加载路径下，当围压小于某个特定值时，围压的变化对盐岩蠕变特性产生一定的影响，当围压高于该值时，盐岩的蠕变特性似乎与围压无关，且从试验结果来看，该值应在4 MPa以上；在恒轴压、循环围压加载路径下，围压及其循环周期对盐岩蠕变特性的影响非常大，降围压阶段盐岩蠕变速率明显高于升围压阶段，且围压循环周期越小，降围压阶段蠕变速率与升围压阶段蠕变速率的比值越大，周期越大，该比值越小。

Test on creep properties of salt rock under different loading paths

To study the influence of loading path on creep property of salt rock, triaxial compression creep experiments with salt rock specimens were carried out under three different loading paths on the RLW 2000 rheology testing machine. The results under the loading path of step loading axial stress with a constant confining pressure show that the instantaneous strain, creep strain and creep rate of salt rock gradually increased as the axial stress increasing, and meanwhile, the duration of the first creep stage gradually extended. And under the loading path of step unloading confining pressure with a constant axial stress, the changes of the confining pressure exert a certain impact on the creep property of salt rock if the confining pressure is less than a certain value, while the creep properties of rock salt seem to be unrelated to the confining pressure if it is greater than the certain value. Based on the test results, the certain value of the confining pressure should be greater than 4 MPa. While, the test results under the loading path of the cyclic confining pressure with a constant axial stress indicate that the confining pressure and its cycle have great influence on the creep property of salt rock, that the creep rate of the confining pressure decreasing stage is obviously greater than that of the confining pressure increasing stage,that the ratio of creep rate of the two stages is closely related to the cycle, and that the shorter the circle is,the greater the ratio.