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煤岩割理系统发育,采用巴西劈裂试验测定煤岩抗拉强度时,由于加载方向和面、端割理所呈夹角不同,试验结果离散性较强,无法准确描述煤岩真实的抗拉强度。假设面、端割理相互垂直,基于平面应力弹性力学,推导了割理倾角与煤岩抗拉强度的关系,依此确定了巴西劈裂试验不同劈裂角度下的煤样破坏方式,通过试验对理论计算结果进行验证,两者趋势吻合较好。研究表明:由于煤岩内部割理的存在,煤样不仅会沿加载轴线发生劈裂破坏,当加载方向与割理呈一定角度时,煤样也可能沿着面割理或端割理发生剪切破坏,煤样沿面割理剪切破坏的强度小于沿端割理剪切破坏的强度,二者均小于沿加载轴线劈裂的煤岩真实抗拉强度。
When the coal splitting test is used to determine the tensile strength of coal and rock, the angle between the loading direction and the face and end cutting is different, the test results are more discrete and can not accurately describe the real resistance of coal and rock Tensile strength. Based on the plane stress elastic mechanics, the relationship between cleat inclination and the tensile strength of coal and rock is deduced. Based on this, the failure modes of coal samples under different cleavage angles in Brazilian cleavage test are determined, The theoretical calculation results are verified, the trend of the two is in good agreement. The results show that the coal sample not only splits along the loading axis due to the internal cleats, but also may cut along the cleavage or end cleavage when the loading direction is at an angle to the cleat Shear failure, the shear strength of the coal along the cleat along the cleat is less than that along the shear cleavage at the cleat, both of which are less than the true tensile strength of the coal rock split along the loading axis.