岩弹冲击破岩规律试验研究

An experimental study on rock breaking law by rock bullet impacting

针对深部岩层掘进过程中钻具磨损快、掘进效率低等问题,基于粒子冲击破岩技术,提出采用高压气体驱动加速岩弹冲击预裂掘进面岩体,减少钻具磨损。通过SHPB试验和三维扫描试验,测试岩石破坏吸收能和新增表面积,构建岩石冲击破坏吸收能理论模型;采用自主研制的岩弹冲击破岩试验装置研究了气体压力、岩弹质量及岩性对破岩效果的影响。形成了以下结论:基于实测岩石破坏吸收能和新增表面积,得出试验花岗岩岩样比表面自由能γs为6.34 mJ/mm^(2);增大气体压力能够有效提高岩弹冲击动能,使花岗岩吸收能和新增表面积增大,同时岩弹破碎和弹射耗散能随之提高,岩弹冲击动能转化为花岗岩破坏吸收能效率降低;吸收能与岩弹质量和动能乘积成幂次方关系,保持气压不变,增大岩弹质量可在一定范围内提高岩弹冲击动能和花岗岩破坏吸收能,提升破坏效果。但过多提高岩弹质量,导致其动能降低,从而使吸收能转化效率降低。不同岩性的岩石比表面自由能不同,但气体压力、岩弹质量对不同岩性岩石冲击破坏效果的影响基本一致。研究结论为硬岩辅助掘进提供理论和技术支撑。

In order to solve the problems of rapid wear of drilling tools and low drilling efficiency in the process of deep rock excavation, based on the particle impact rock breaking technology, a method of using high-pressure gas to accelerate the impact of rock bullets on the pre-cracked rock mass of the advancing face was proposed to reduce the wear of drilling tools. An SHPB experiment and a three-dimensional scanning experiment were used to test the absorbed energy of rock failure and the newly added surface area, and a theoretical model for calculating the absorbed energy of rock impact failure was constructed. At the same time, a self-developed rock bullet impact rock breaking experimental device was used to study the influence of gas pressure, bullet mass and lithology on the rock breaking. Results show that the specific surface free energy γsof the experimental granite rock sample was 6.34 mJ/mm^(2), based on the measured rock fragmentation absorbed energy and added surface area. Increasing the gas pressure can effectively increase the impact kinetic energy of rock bullets, the absorbed energy of granite and the new surface area. At the same time, the crushing and ejection energy of rock bullets will increase, and the efficiency of the impact kinetic energy of rock bullets into granite crushing will be reduced. The absorbed energy is a power product of the mass and kinetic energy of the rock bullets. Keeping the air pressure constant and increasing the mass of the rock bullets can increase the kinetic energy and absorbed energy conversion efficiency of the rock bullets within a certain range, and enhance the damaging effect. Too much increase in rock mass will result in a decrease in kinetic energy, thereby reducing the conversion efficiency of absorbed energy. The specific surface free energy of rocks with different lithology is different. However, the effects of gas pressure and mass of rock bullets on the impact failure effect of rocks with different lithology are basically the same. This work may provide theoretical and technical support for hard rock auxiliary excavation.