冲击作用下囊袋式炮孔堵塞结构性能试验研究

Experimental Study on Blocking Structure Performance of Bag-type under Impact

针对大直径深孔爆破要求质量高、传统堵塞材料长度过长且容易“冲孔”,提出以早强水泥砂浆为堵塞材料,选用囊袋式结构作为新型炮孔堵塞物。对不同掺加剂含量、不同龄期的水泥浆进行了静态力学试验与冲击荷载作用下的堵塞模型试验,通过试验得到在不同变量下水泥砂浆的自收缩性能、抗压强度与冲击荷载作用下管壁的被动围压,分析被动围压下早强水泥砂浆的动态力学特性;分析爆生气体压力作用下堵塞物在炮孔中受力特性,给出大直径深孔炮孔合理堵塞长度。结果表明:试件的自收缩随着掺加剂含量的提高而增大;试件抗压强度随着龄期的增长而增大,掺加剂含量的提高而减小;随着掺加剂的含量和龄期的增加,膨胀压力增大,从而被动围压增大,当掺加剂含量为4%、16 h龄期时,各个测点的膨胀压力达到峰值,另外随着掺加剂含量的提高,浆液的孔隙增多,堵塞体轴向可压缩性越高,能够延长爆生气体压力在炮孔中作用时间,提高堵塞质量;综合现场试验结果表明,依据所推导理论公式结合现场生产合理选取爆破堵塞长度保证了回采期间的安全生产,深孔爆破取得了良好的效果。

In response to the high-quality requirements for large-diameter deep-hole blasting,and the traditional stemming material being too long and prone to“blowout”,a new type of blasting hole stemming material was proposed using early strength cement mortar and a bag-like structure.Static mechanical tests and blockage model tests under impact loads were conducted on cement slurry with different admixture contents and ages,and the self-shrinkage performance,compressive strength,and passive confinement pressure of the cement mortar under impact loads were analyzed to determine the dynamic mechanical properties of the early strength cement mortar under passive confinement.The stress characteristics of the stemming material in the blasting hole under the pressure of the blasting gas were also analyzed to provide a reasonable stemming length for large-diameter deep-hole blasting.The results showed that the self-shrinkage of the test piece increased with the increase of admixture content.The compressive strength of the test piece increased with the increase of age and decreased with the increase of admixture content.With the increase of admixture content and age,the expansion pressure increased,resulting in an increase in passive confinement pressure.When the admixture content was 4%,and the age was 16 hours,the expansion pressure reached its peak at each measuring point.Additionally,with the increase of admixture content,the porosity of the slurry increased,the axial compressibility of the blocking material increased,and the acting time of the blasting gas pressure in the blasting hole was prolonged,which improved the stemming quality.Comprehensive on-site test results have shown that the stemming length,reasonably selected based on the derived theoretical formula and combined with on-site production,ensures safe production during the mining period,and achieves good results in deep-hole blasting.