煤与软弱夹层组合体裂纹扩展及变形破坏规律数值模拟研究

Numerical simulation study on crack propagation and deformation failure law ofcoal and weak interlayer combination

针对含软弱夹层煤体承压力学性状复杂、现场容易引发片帮的问题,采用实验室试验和数值模拟方法,对不同位置和厚度夹层组合体进行了研究,揭示煤与夹层组合体裂纹扩展及变形破坏规律。研究结果表明,随着夹层厚度的增加,组合体试样的强度降低,组合体达到峰值前的应变滞后,表明软弱夹层有助于提升组合体的变形程度,降低组合体的整体刚度和弹性模量;随着夹层位置由组合体上部向下部移动,组合体整体抵抗变形和破坏的能力逐渐减弱,强度大小为:无夹层>1/4上部>中部>3/4下部;随着压缩程度的增加,破坏现象逐渐向夹层上部以及下部层位转移,加载初期上部层位裂纹占比逐渐增加,裂纹发育扩展具有优先性,当组合体承载达到峰值后,下部层位裂纹占比增大,破坏才会发生并逐渐增强。研究成果可为控制巷道及工作面片帮、破坏失稳等提供理论参考。

Considering the intricate mechanical characteristics of the coal body with weak interlayer under pressure,which can easily lead to the problem of spalling on site,laboratory experiments and numerical simulations were used to study the crack propagation and deformation failure laws of coal and interlayered combination at different positions and thicknesses.The findings indicate that with an increase in the interlayer thickness,the strength of the combination sample diminishes,and the strain exhibits a lag before the combination reaches its peak value.This phenomenon suggests that the weak interlayer contributes to escalating the degree of deformation in the combination,consequently reducing its overall stiffness and elastic modulus.The overall capacity of the composite to withstand deformation and harm diminishes gradually as the position of the interlayer transitions from the upper section to the lower section of the combination.The relative strength levels are as follows:no interlayer>1/4 upper part>middle part>3/4 lower part.As the degree of compression intensifies,the occurrence of failure gradually relocates to the upper and lower interlayer strata.At the initial stage of loading,the proportion of cracks in the upper layer gradually increases,and the development and expansion of cracks have priority.When the combination reaches its peak load,the percentage of cracks in the lower layer increases,and failure will occur and gradually strengthen.The research results can provide theoretical reference for controlling roadway and working face spalling,failure and instability,etc.