分层装药爆破间隔填塞长度优化研究

分层装药爆破在工程中应用广泛,其具有良好的爆破减振和提高孔口堵塞段破碎等效果。但是在实践中,合理的中间填塞长度选择一直缺乏依据。通过有限元软件LSDYNA对90 mm孔径6 m深的炮孔分别建立中间填塞段长度为25~105 cm的五个模型,上、下药包装药量固定,耦合装药,以爆破损伤以及单元所受最大拉应力两个指标来分析填塞段长度对分层爆破效果的影响。结果表明:中间填塞长度过短,能量集中作用于中间段,会导致岩石过于粉碎;中间填塞长度的增加,孔口堵塞段岩体破碎效果也随之改善,填塞长度105 cm和25 cm相比,地表处单元所受最大拉应力增加了约1倍,但中间段破碎效果弱化;当中间填塞段长度为85 cm时,中间填塞段岩体和上部岩体均有较好的破碎效果;通过振动分析,中间填塞长度变化对离炮孔较远区域爆破振动的影响较小。基于数值模拟结果的工程试验表明,最佳中间填塞段长度为85~95 cm,较数值模拟结果稍大。

Optimization on Interval Stemming Length of Blasting in layered Charge

Layered charge blasting has been widely used,which can reduce blasting vibration and improve blasting effect.But the rational choice of the middle packing length lacks support in practice.A numerical model was built with LS-DYNA,the borehole diameter is 90 mm,and hole length is 6 m.The upper charge and lower charge are unaltered and coupling charge.The damage and the maximum tensile stress were analyzed with the middle stemming length varying from 25 cm to 105 cm.The results show that if the middle stemming length is too short,the explosion energy focuses on rock close to middle stemming part,and the rock mass nearby will be over cracked.The blasting effects of upper part of the model are improved with the increase of middle stemming length.When the middle stemming length is 105 cm,the maximum tensile stress of surface unit is twice of 25 cm,but the fragmentation effect of rock close to the middle stemming is weakened.The maximum tensile stress tends to be the largest when the middle stemming length is 85 cm;The changing of middle stemming length has little effect on blasting vibration.Finally,the optimized results are applied to a rock blasting project,and the best middle stemming length is 85~95 cm.