Abstract

Abandoned roadways of coal mines are suitable for compressed air energy storage after proper treatment with grouting reinforcement and concrete lining. According to the theoretical analysis, the rock mass and concrete lining will experience cyclic tensile stress in the air injection-withdrawal process which is unfavorable to the long-term stability of the roadway. At present, few researches have focused on mechanical properties of rock under cyclic tensile stress. Therefore, cyclic tests were conducted for sandstones under different maximum tensile stresses and different cyclic frequencies, respectively. The test results showed that there was little damage in the sandstone until the maximum tensile stress was over the threshold which was about 75% of the average tensile strength of the sandstone. Besides, the rock was damaged more easily under lower cyclic frequency. Based on the testing results, a viscoelastic-plastic model for sandstone was constructed under cyclic tensile stress. The model parameters were fitted by optimization analysis method and used to predict mechanical behaviors of the sandstone. The results showed that the response of the rock could be well obtained by the proposed model.

Article highlights

• Lower cyclic frequency of tensile stress makes sandstone sample more favorable to be broken.

• The sample tested under low cyclic frequency of tensile stress will generate time-depending tensile strain inside.

• The time-depending tensile strain evolution properties of the sample under different testing conditions can be uncovered by a model constructed by different basic mechanical elements and a self-defined element.

中文翻译：

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循环拉应力作用下砂岩的试验研究及粘弹塑性模型

摘要

煤矿废弃巷道经注浆加固和混凝土衬砌适当处理后，适合用作压缩空气储能。根据理论分析，在注气—抽气过程中，岩体和混凝土衬砌会产生循环拉应力，不利于巷道的长期稳定性。目前，对循环拉应力作用下岩石力学特性的研究较少。因此，分别对不同最大拉应力和不同循环频率下的砂岩进行了循环试验。试验结果表明，在最大拉应力超过阈值时，砂岩几乎没有损伤，该阈值约为砂岩平均抗拉强度的 75%。除了，在较低的循环频率下，岩石更容易受到破坏。根据试验结果，建立了砂岩在循环拉应力作用下的粘弹塑性模型。模型参数通过优化分析方法拟合，用于预测砂岩的力学行为。结果表明，该模型可以很好地获得岩石的响应。

文章亮点

• 较低的拉应力循环频率使砂岩样品更容易破碎。

• 在低循环频率拉伸应力下测试的样品会在内部产生随时间变化的拉伸应变。

• 样品在不同测试条件下的时变拉伸应变演化特性可以通过由不同基本机械元件和自定义元件构建的模型来揭示。