拉剪作用下煤岩不等长平行偏置裂纹相互作用

Interaction of unequal offset parallel cracks under tension-shear stress in coal

为研究天然煤岩体中多裂纹的相互作用规律,采用经典Kachanov法,通过分析应力强度因子比的变化,研究了拉剪作用下不等长平行偏置双裂纹间水平距离、垂直距离以及裂纹长度对彼此相互作用的影响规律.并借助RFPA2D软件对不同间距条件下的裂纹起裂扩展进行数值模拟验证,其结果与理论计算吻合良好.结果表明:裂纹间的相互影响包括强化作用、屏蔽作用和零效应3种形式,且三者随水平距离、垂直距离和裂纹长度的不同而相互转化;距离裂纹尖端越近,强化作用越强烈,且强化作用变化速率也越快,距离裂纹中心越近,屏蔽作用越强烈,且屏蔽作用变化速率也越快,裂纹长度越长,其影响范围也越大.

In order to research the interaction rules of multiple cracks in coal and rock mass, based on Kachanov method, the interaction rules of two unequal offset parallel cracks with different level interval, vertical interval and crack length were analyzed by stress intensity factor ratio under tension-shear stress. The processes of crack initiation and propagation were simulated by RFPA2D, and the simulation results fit the theory well. The results show that the interactions of offset parallel cracks include exist reinforcing effect and shielding effect, and the two effects transform mutually with the variations of level interval, vertical interval and crack length; The reinforcing effect becomes more and more severe with the decrease of distance to the crack tip, and the rate of change becomes faster too. The shielding effect becomes more and more severe with the decrease of distance to the center of crack, and the rate of change becomes faster too. The influence range of crack becomes more and more wide with the increase of length.