特厚煤体爆破致裂机制及分区破坏的数值模拟

为了优化并确定顶煤爆破参数,通过对爆破致裂机制的探讨,推导了爆炸作用下裂纹应力强度因子的表达式,给出了裂纹继续扩展的判断准则和裂隙区、压碎区的判定准则,运用理论分析和数值计算手段揭示了爆破致裂特性,分析了不同装药半径条件下爆破后煤体的压碎区、裂隙区范围。综合分析表明:爆炸后形成的压碎区、裂隙区与炸药性能及被爆体的物理力学特性有关,爆炸最终形成的压碎区、裂隙区半径与装药半径的比值不变,但压碎区和裂隙区半径随装药量的增加而加大。讨论认为裂隙区半径研究结果差异较大的原因与研究对象对爆破扰动的要求程度有关,爆破提高特厚、坚硬煤体冒放性主要与爆破致裂产生的宏观裂隙区有关。宏观裂隙区在15rb范围内,15rb以上的区域是微观裂隙萌生区。在进行涉及到安全防护方面的方案设计时,为保障安全性,必须考虑微观裂隙区的大小。

Extra-thick coal blasting mechanism and numerical simulation of partition failure

In order to optimize and determine the parameters of blast in top-coal，through the study of fracturing mechanism of blasting， the expression of crack stress intensity factor under explosion was derived，a criterion for judging the crack expand criterion and judgment criterion of crushed zone and fracture zone was given，the theoretical analysis and numerical calculation method were used to reveal the blasting characteristics，the crushing zone and fractured zone were analyzed at different charge radius after blasting.Comprehensive analysis shows that the crushed zone and fractured zone are related to the explosive performance and the physical and mechanical properties of blasted body，the value of crushed zone radius and fractured zone radius divided by charge radius is unchanged，but the radius of crushed zone and fractured zone increases with the increase of charge.The reason for the larger differences on radius of fracture zone is that the requirements degree of blasting disturbance for the study object is different，macro fracture zone play an chief role in improving top-coal caving for the extra-thick and hard coal by blasting.The macro fracture zone is 15rb，the micro crack initiation region is beyond the 15rb.To ensure safety，micro crack zone must be considered in program design involved by the safety protection field.