论文部分内容阅读
为了研究炸药在不同煤岩介质中爆破所产生的裂隙扩展和力学特征,提高深孔预裂爆破对低透气性煤层进行增透的效果,在实验室搭建爆破模拟试验系统,设计穿层钻孔和顺层钻孔2种不同的装药模式,以Froude比例法建立煤层深孔预裂爆破的试验模型,利用相似材料配比加工制备尺寸为50 cm×50 cm×50 cm的试样进行爆破模拟试验。通过超动态应变仪监测煤岩层的应变信号,利用高速摄像仪记录试样完整的裂纹萌生、扩展、贯通直至试样破坏的全过程,分析爆破载荷作用下试样的动态力学特性和裂纹扩展特性。研究发现,裂纹主要是由压缩波与卸载波共同作用形成的,裂纹扩展方向与炮孔轴线方向垂直;在煤岩介质中实施穿层钻孔爆破的爆破效果优于顺层钻孔煤层爆破效果,当爆破应力波从煤层入射到岩层后,出现反射拉伸波,反作用于煤体上,加剧煤岩不同爆破介质的破坏程度,促使爆破裂隙的扩展。研究成果可用于指导井下低透气性煤层深孔预裂爆破装药方式的选择,以提高瓦斯抽采效率。
In order to study the crack propagation and mechanical characteristics caused by blasting of explosives in different coal and rock media and to enhance the effect of deep-hole pre-cracking blasting on the permeability enhancement of low-permeability coal seam, a blasting simulation test system was set up in the laboratory to design the borehole And the two different charge modes of drilling in the same layer. The experimental model of deep-hole presplitting blasting in coal seam was established by Froude’s proportional method. The samples with the size of 50 cm × 50 cm × 50 cm test. The dynamic strain gauge was used to monitor the strain signal of coal rock and the complete crack initiation, propagation and penetration were recorded by high-speed camera. The whole process of specimen failure was analyzed. The dynamic mechanical properties and crack propagation properties . It is found that the crack is mainly formed by the interaction of compressional wave and unloading wave, and the direction of crack propagation is perpendicular to the axis of the blasting hole. The blasting effect of penetrating borehole blasting in coal and rock media is better than the blasting effect When the blasting stress wave is incident on the rock bed from the coal seam, the reflected tensile wave appears and acts on the coal body to exacerbate the damage degree of different blasting media of coal rock and promote the expansion of the blasting fracture. The research results can be used to guide the selection of deep-hole pre-cracking blasting in low permeability coal seam to improve the gas drainage efficiency.