1. School of Mechanics and Architecture Engineering,China University of Mining and Technology (Beijing),Beijing　 100083,China;2. State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology (Beijing),Beijing　 100083,China

利用爆炸加载数字激光动态焦散线试验系统(DLDC),研究了两切槽炮孔爆破爆生主裂纹和由预制缺陷尖端衍生的次裂纹扩展的动态力学行为。研究结果表明,两切槽炮孔同时起爆后,爆生主裂纹没有相互交汇贯通而是止于预制裂纹断面处,表明缺陷对定向断裂控制爆破效果有着重要的影响;次裂纹与主裂纹并没有直接贯通,而是呈"勾连状"的止于对方裂纹面上。与水平预制缺陷相比,垂直预制缺陷对主裂纹的扩展影响更大,其次裂纹在拉伸应力场的作用下而以I型扩展;当膨胀P波与运动着的裂纹相互作用时,裂纹扩展速度和裂尖动态应力强度因子都减小。

The dynamic behavior of blast-induced cracks propagation between two notched boreholes in PMMA materi- al with prefabricated crack under blasting load was studied by a new digital laser experimental system of dynamic caus- tics. The experimental results show that ① in the simultaneous blasting process for the double notched boreholes,the interaction between the prefabricated crack and the blast-induced main crack interdicts the propagation of blast-in- duced main crack and the coalescence of two blast-induced main cracks,which indicates that the prefabricated crack has great influence on the directional fracture controlled blasting;② the blast-induced secondary cracks generated at the tips of horizontal prefabricated crack and the blast-induced main cracks do not meet directly in the propagating process,but move to the near blast-induced main crack surface,which leads to blast-induced secondary cracks growth in a curved way. Compared with the horizontal prefabricated cracks,the vertical one has even greater influence on the propagation of the blast-induced main crack. The blast-induced secondary cracks are mainly affected in tension stress field and expand with mode I;③ the values of propagating speed and dynamic stress intensity factor are reduced by the interaction between the frontal compression wave of P wave in explosive stress wave and propagating crack.

国家自然科学基金煤炭联合基金重点资助项目(51134025)；深部岩土力学与地下工程国家重点实验室自主重点课题资助项目(GDUEZB201401)；国家留学基金建设高水平大学公派研究生项目(201306430033)；

Wang Yanbing,Yang Renshu,Ding Chenxi,et al. Dynamic caustics experiment on crack propagation of defective medium under the effect of explosive stress waves of double holes[J]. Journal of China Coal Society,2016,41(7):1755-1761.