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干湿循环对红砂岩力学特性及损伤影响试验研究

Experimental study on influence of wetting-drying cycles on mechanical characteristics and damage of red sandstone

  • 摘要: 为了研究干湿循环对红砂岩煤矿井壁和巷道的力学特性及损伤劣化,将红砂岩进行不同次数的干湿循环,然后在MTS815岩石力学试验机上进行压缩试验,研究表明:红砂岩干湿循环次数增加,结构由致密连续向多孔疏松转变,微裂隙压密阶段持续时间增长,塑性屈服明显,峰值应变增加,弹性模量降低,峰值强度大幅下降,但强度不会一直降低,而是趋于某一值;单轴压缩下干湿循环10次时,塑性变形特征明显;随着围压的増大,压密阶段持续时间减小,峰值应变降低,弹性模量增大,峰值强度得到较大提高,峰后塑性变形显著,残余强度随之増强。基于热力学定律和能量耗散原理建立的不同干湿循环次数下红砂岩损伤演化方程和试验结果相近,研究结果可为井壁、巷道设计和支护提供参数。

     

    Abstract: In order to study the mechanical properties and damage deterioration of the red sandstone coal mine shaft and roadway during thewetting-drying cycles, the red sandstone was subjected to different cycles of wetting-drying cycles, and then compression tests were performed on the MTS815 rock mechanics tester. The study showed that the red sandstone wetting-drying cycles with increasing number of times, the structure changes from dense to porous, the microfissure compaction stage increases in duration, the plastic yields significantly, the peak strain increases, the elastic modulus decreases, and the peak strength decreases significantly, but the strength does not decrease all the time but tends to added to a certain value; under uniaxial compression ten cycles of wetting-drying cycles, the plastic deformation characteristics are obvious; with the confining pressure increases, the duration of the compaction phase decreases, the peak strain decreases, the elastic modulus increases, the peak intensity gets larger as a result, the post-peak plastic deformation is significant and the residual strength is reluctantly increased.Based on the laws of thermodynamics and the principle of energy dissipation, the damage evolution equations and experimental results of red sandstone under different cycles of wetting-drying cycles are similar. The research results can provide parameters for well wall and roadway design and support.

     

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