组合体中岩石部分裂缝长度对煤岩组合体力学特征的影响

Influence of Partial Crack Length of Rock in Assemblage Body on Mechanical Characteristics of Coal-rock Assemblage Body

针对煤矿开采过程中顶底板岩石不同长度裂缝对遗留煤柱与顶底板岩石形成的煤岩组合体试样力学特性的影响,通过数值模拟软件颗粒流分析程序PFC建立了裂缝五种不同长度的煤岩组合体数值模拟模型,开展了单轴压缩数值模拟试验,获得了裂缝长度对煤岩组合体试样强度、变形、微裂纹变化及声发射变化特征的影响。随着岩石部分裂缝长度的增加,岩石含裂缝的煤岩组合体试样的峰值应变和峰值强度均呈先增加后减小的趋势,弹性模量则呈单调递减变化趋势,微裂纹呈先增加后减小再增加再减小的趋势。在裂缝长度为4 mm时,煤岩组合体中的微裂纹数目最多4802个;裂缝长度为36 mm时,微裂纹数目最少。煤岩组合体的破坏主要发生在组合体的煤体部分。研究对于了解裂缝长度对煤岩组合体试样的力学特征及煤岩组合结构的稳定性具有重要意义。

In view of the influence of different lengths of cracks in the roof and floor rocks during coal mining process on the mechanical characteristics of coal-rock assemblage body specimens formed by residual coal pillars and roof and floor rocks,five numerical simulation models of coal-rock assemblage bodies with different lengths of cracks are established using the particle flow analysis program PFC in numerical simulation software.Uniaxial compression numerical simulation experiments are conducted to obtain the influence of crack length on the strength,deformation,microcrack variation,and acoustic emission variation characteristics of coal-rock assemblage body specimens.As the length of partial cracks in the rock increases,the peak strain and peak strength of the coal-rock assemblage body specimens containing cracks show a trend of first increasing and then decreasing,while the elastic modulus shows a variation trend of monotonically decreasing,the microcracks show a trend of first increasing,then decreasing,then increasing,and then decreasing.When the crack length is 4 mm,the maximum number of microcracks in the coal-rock assemblage body is 4802,and when the crack length is 36 mm,the number of microcracks is the lowest.The failure of coal-rock assemblage body mainly occurs in the coal body part of the assemblage body,and research is of great significance for understanding the influence of crack length on the mechanical characteristics of coal-rock assemblage body specimens and the stability of coal-rock assemblage structures.