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碳纤维布约束下煤样力学性能与能量损伤本构关系

Mechanical properties and energy damage constitutive relationship of coal samples confined by CFRP sheets

  • 摘要: 为探讨碳纤维增强复合材料(CFRP)布约束对煤样力学性能及能量损伤行为的影响, 通过改变CFRP布层数, 对煤样进行轴压加载试验, 分析裂纹压密、线弹性、屈服和峰后破坏4个阶段的应力−应变变化, 研究CFRP布对煤样能量输入、积聚、耗散和释放过程的影响。结果表明: 随CFRP布层数的增加, 煤样的裂纹闭合应力和起裂应力先增后减, 但均高于未约束状态, 表现出显著的约束效果和边际递减特性; CFRP布有效限制了煤样内部裂纹扩展, 改善应力分布, 使破坏过程更缓慢有序, 显著提升了承载能力和延性, 并减少峰后应力骤降现象; CFRP布增强了煤样的能量输入和分布均匀性, 降低能量释放速率, 改善了能量分布和破坏过程。CFRP布约束能显著改善煤样的力学性能和能量耗散特性, 提出的耗散能损伤因子模型验证了CFRP布对延缓损伤累积和裂纹扩展的有效性。推导CFRP布包裹层数与等效煤圆柱套筒厚度的数学关系, 深化了对煤柱加固机制的理解, 并为提升房柱式采空区煤柱遗煤资源采出率提供了经济高效的加固新视角。

     

    Abstract: To investigate the confinement effect of carbon fiber-reinforced polymer (CFRP) sheets on the mechanical properties and energy damage behavior of coal samples, uniaxial compression tests were conducted on coal samples with varying layers of CFRP sheets. The stress-strain changes during the four stages of crack compaction, linear elasticity, yield and post-peak failure were analyzed, and the influence of CFRP sheets on the energy input, accumulation, dissipation, and release processes in coal samples was studied. The results show that the crack closure stress and crack initiation stress of coal samples first increased and then decreased with the increase in CFRP layers, but still higher than that in the unconfined state, demonstrating a significant confining effect and a marginal diminishing feature. The CFRP sheets effectively constrained the internal crack propagation in coal, improved stress distribution, made the failure process slower and more orderly, significantly enhanced the load-bearing capacity and ductility, and reduced the post-peak stress drop phenomenon. The CFRP sheets enhanced the energy input and distribution uniformity of coal samples, reduced the energy release rate, and improved the energy distribution and failure process. CFRP confinement significantly improved the mechanical properties and energy dissipation characteristics of coal samples. The proposed dissipated energy damage factor model verified the effectiveness of CFRP sheets in delaying damage accumulation and crack propagation. A mathematical relationship was derived between the layers of CFRP sheets and the equivalent coal cylindrical sleeve thickness. The research advances the understanding of coal pillar reinforcement mechanism and provides an economical and efficient new perspective for improving the recovery rate of residual coal resources in room-and-pillar mining.

     

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