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以建立煤岩体耦合致裂方案与强度劣化之间的关系为目标,将注水和爆破这2种措施的共同作用定义为耦合致裂,分析耦合致裂机制,给出耦合致裂时裂纹的扩展准则,提出固–液耦合态模型在爆炸荷载作用下的强度劣化分析方法,运用数值模拟方法建立注水模型及爆炸荷载制取模型,在完成爆炸荷载施加后对模型实施轴向加载,分析不同耦合致裂方案作用下模型整体强度的劣化程度。结果表明:耦合致裂的本质是爆炸形成的爆生气体和冲击波共同在已软化的煤岩体中传播,耦合致裂效果大于两者的简单叠加;提高注水压力可提高煤岩体的强度劣化率,随着钻孔孔径加大即装药量的增加,模型强度下降显著。获得耦合致裂参数与强度劣化率f的关系,定量评估了炸药单耗和注水压力所对应的煤体破坏程度。工程实践为例,求得急倾斜特厚煤层综放工作面煤体耦合致裂后的强度为5.48 MPa,相比实施注水后煤体的强度又降低了40.07%。工作面回采率满足了国家标准对厚煤层回采率的要求,达到了提高顶煤回收率的目的,为定量评估耦合致裂效果提供了试验方法与依据。
In order to establish the relationship between the coupling cracking of coal and rock mass and the strength degradation, the joint action of water injection and blasting is defined as coupling cracking, and the coupling cracking mechanism is analyzed. The criterion of strength degradation of solid-liquid coupled model under explosive load is proposed. The model of water injection and the model of explosive load are established by numerical simulation. After the explosion load is applied, the model is axially loaded and analyzed. The degree of deterioration of the overall strength of the model under coupled cracking scheme. The results show that the essence of coupling cracking is that the explosive gas and shock wave propagated in the explosion propagate together in the softened coal and rock mass, and the coupling cracking effect is larger than the simple superposition; the increase of water injection pressure can improve the strength deterioration of the coal and rock mass Rate, with the increase of borehole diameter, the charge increased, the model strength decreased significantly. Obtained the relationship between the coupling fracture parameter and the strength degradation rate f, and quantitatively evaluated the damage degree of the coal body corresponding to the unit charge of explosive and water injection pressure. For example, the strength of the fully mechanized coal caving face in the steep-inclined and ultra-thick coal seam after the coupling failure is 5.48 MPa, which is 40.07% lower than that of the water injection. Face recovery rate to meet the national standards for the recovery of thick coal seam rate requirements, to achieve the purpose of improving the recovery of top coal, quantitative evaluation of coupling cracking effect provides the test method and basis.