深孔掏槽超深爆破破岩机制及最佳超深值研究

Mechanism of rock breaking by deep hole ultra-deep cut blasting and the optimum ultra-deep value determination

岩巷掘进中“速度的关键在掏槽”。针对目前掏槽爆破中单循环进尺小、200mm掏槽孔超深爆破技术已经较为落后等问题,研究深孔掏槽超深爆破破岩机制,并采用数学建模的方法,推导超深爆破中岩石破碎抛掷所受阻力和动力公式,分析不同超深值对掏槽体积的影响;利用AUTODYN模拟掏槽范围内岩石的抛掷速度变化规律,初步确定最优掏槽孔超深值为400mm;在岩巷掘进现场应用深孔掏槽超深爆破技术,对比不同超深值爆破方案及传统楔形爆破方案的爆破效果评价指标。结果表明,适当增加超深值会使裂隙充分延伸,岩石破碎得更为彻底,形成体积更大的掏槽槽腔;但过度增加超深值会导致岩石抛掷阻力过大,裂缝延伸长度降低,不利于增大掏槽槽腔体积。工程实践表明,400mm的掏槽孔超深值能够在取得理想爆破效果的同时提高工作效率,具有良好的经济社会效益。

Cutting is the key to improve the speed of rock roadway driving.Aiming at the problems of small single cycle footage and backward ultra-deep blasting technology of 200 mm cutting hole,the rock breaking mechanism of deep hole cutting ultra-deep blasting is studied.The mathematical modelling method is adopted to derive the resistance and dynamic formula of rock breaking and throwing in ultra-deep blasting,and analysis the influence of different ultra-deep values on cutting volume.AUTODYN is used to simulate the throwing velocity of rock in the cutting range,and determine the optimal cutting hole depth by 400 mm.Deep hole cutting ultra-deep blasting technology is applied in rock tunnel excava-tion field.The blasting effect evaluation indexes are compared in different schemes of ultra-deep blasting and traditional wedge blasting.The results show that the cracks will be fully extended with the increase of the ultra-deep value appropriately,which could result in more thorough rock break and larger cutting cavity.However,excessive increase of super-deep value will lead to excessive throwing resistance of rock and decrease of crack extension length,which is not conducive to increasing the volume of cutting cavity.Engineering practice shows that the ultra-deep value of 400 mm cut hole could achieve the desired blasting effect and improve work efficiency,with good economic and social benefits.