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到目前为止,很少有人较深入地研究盐岩流变加速阶段的特性。利用微机控制三轴流变试验机,对盐岩试样进行三轴分级加载流变-损伤破坏试验。将第一作者提出的一维流变-损伤模型进行三维扩展,采用对时间的差分计算流变变形与损伤变量及变形,对试验数据进行拟合分析,较深入地研究了盐岩的流变损伤-破坏特性,得到了全程流变-损伤曲线,获得了过渡蠕变、稳态流变和加速流变各阶段的盐岩变形与损伤发展规律。模型对盐岩的加速流变-损伤阶段特性的描述与实验数据吻合较好,揭示了盐岩流变-损伤破坏特性。研究表明,分级加载条件下,盐岩的过渡蠕变不容忽视;盐岩的流变-损伤随时间增长与荷载水平加大而发展,由稳态流变-损伤到加速流变-损伤并没有十分明显的界限;损伤严重时,损伤引起的变形将在总变形中起决定性作用;一旦损伤变量超过损伤增速界限,宏观上流变/损伤达到加速阶段。
So far, few have studied in depth the characteristics of salt rock rheology acceleration. Three-axis rheological testing machine controlled by computer was used to carry out rheological-damage damage test on salt rock samples by triaxial staged loading. The one-dimensional rheological-damage model proposed by the first author was extended three-dimensionally. The rheological deformation and damage variables and deformation were computed by the difference of time, and the experimental data were fitted and analyzed. The rheology of salt rock The damage-destruction characteristics of the rock mass are obtained, and the whole rheological-damage curve is obtained. The deformation and damage development of rock salt in transitional creep, steady-state and accelerated-rheological stages are obtained. The model’s description of the accelerated rheology-damage phase characteristics of salt rock is in good agreement with the experimental data, revealing the rheological-damage damage characteristics of salt rock. The results show that the transitional creep of salt rock can not be neglected under the condition of graded loading. The rheological-damage of salt rock develops with the increase of time and loading level, from steady state rheology-damage to accelerated rheology-damage Very obvious boundaries. When the damage is serious, the deformation caused by the damage will play a decisive role in the total deformation. Once the damage variable exceeds the limit of damage growth, the macro-rheology / damage reaches the acceleration stage.