1. School of Mechanic & Civil Engineering,China University of Mining & Technology(Beijing),Beijing　 100083,China;2. State Key Laboratory of Geome-chanics and Deep Underground Engineering,Beijing　 100083,China

采用动态焦散线实验方法,研究爆炸荷载作用下邻近硐室背爆侧裂纹扩展规律时发现,伴随爆生气体释放出现的弧线型应力集中区是爆生气体引起的主应力差峰值位置,与背爆侧裂纹的扩展有较大的关联。实验研究表明:炸药爆炸后,产生的应力波首先作用于硐室背爆侧裂纹,随后爆生气体产生的准静态应力作用于裂纹,对裂纹的扩展起主要作用,而卸载波主要作用于裂纹扩展后期,使裂纹出现翘曲现象。当弧线型应力集中区接近扩展中的裂纹时,裂纹扩展速度达到峰值,约等于弧线型应力集中区的移动速度,之后,裂纹尖端与弧线型应力集中区的相对距离基本不变,当该应力集中区越过裂纹尖端,裂纹扩展速度逐渐减小,最终止裂。裂纹尖端动态应力强度因子与裂纹扩展速度具有相似的变化规律,峰值动态应力强度因子出现在弧线型应力集中区越过裂纹尖端之前。基于该发现进行的研究证实了爆生气体对邻近巷道裂纹扩展的主导作用,深化了爆炸荷载对邻近巷道影响机理的研究。

During the research about crack extension rule at the back-side of adjacent tunnel under the action of blas- ting load adopting the dynamic caustics experimental method, a relationship exists between the crack extension in back-side of tunnel to blasting and arc type stress concentration region which appears with the release of detonation gas. Study shows that after the explosion,the explosion stress wave acts on the crack in the back-side of tunnel firstly, then the quasi-static stress field produced by detonation gas acts on the crack,which plays a main role on the propaga- tion of the crack. Finally,unloading wave acts on crack,and the crack warps. When the arc type stress concentration region moves near the tip of propagation crack,the crack extension velocity reaches to maximum,which equals to the velocity of wave front. Later the relative distance between the crack tip and arc type stress concentration region doesn’t change basically. When the arc type stress concentration region extends cross the crack tip,the extension ve- locity gradually decreases,finally,the crack arrest. Similar changing rule happens on the dynamic stress intensity fac- tor. Dynamic stress intensity factor reaches peak before the arc type stress concentration region runs across the crack tip. Research based on the findings confirms that the detonation gas plays a dominant role to the crack propagation in adjacent tunnel. The researches enable a better understanding on the impact mechanism of explosion load on neighbor- ing tunnel.

国家自然科学基金资助项目(51274204；51134025)；教育部新世纪优秀人才支持计划资助项目(NCET-12-0965)；

Guo Dongming,Liu Kang,Hu Jiuxian,et al. Experimental study on the effect mechanism of the explosion gas on the precrack in the back- blasting of adjacent tunnel[J]. Journal of China Coal Society,2016,41(1):265-270.