冲击载荷下脆性岩板损伤断裂演化的实验模拟研究

Simulation Research for Impact Damage Fracture Evolution of Brittle Rock Plate Under Impact Loading

在矿山运输系统中,井壁围岩冲击损伤破坏对经济和安全效益的影响是至关重要的,因为动态冲击载荷对井壁围岩和支护结构会产生严重的削弱破坏作用,室内研究表明,岩石样品如岩板在动态载荷的冲击作用下会失效。为研究在低速冲击载荷作用下,脆性岩石损伤断裂的演化过程,利用分离式霍普金森压杆(SHPB)装置中压缩气体发射球体子弹对脆性岩板进行变角度冲击损伤实验,岩板受到冲击后,边缘出现凹坑,表面裂纹从撞击凹坑直达岩板边缘,实验中样品的表面裂纹能有效代表试样内部的开裂状况,能有效反映冲击能量的耗散、破裂区面积与裂纹表面积随入射能量呈非线性增长趋势,同时与入射角度相关,但当破裂区面积急剧下降时,裂纹表面积反而急剧上升,表明裂纹的发生发展有明显的孕育期,在入射能量达到临界值前,主要表现为裂纹孕育增长,在达到临界值后,发生宏观断裂破坏,裂纹面积呈负增长,破裂区面积增大。实验结果分析表明在实际工程中,围岩和支护结构的抗冲击的最优化设计角度范围在15°～30°。

In order to study the evolutionary process of brittle rock damage and fracture under low-velocity impact loading,the dynamic damage was studied by variable angle impact test using compressed gas of SHPB to launch the ball to impact the lateral margin of rock plate.When a source of impact loading was applied to a rock plate specimen,damage cracks were developed from the source to the boundaries,and the surface cracks effectively represened sample internal cracking condition and reflected the impact energy dissipation in these tests.Test results showed that the cracks propagation length and break area are not arbitrary,but are influenced by the angle of dynamic impact loading.The crack length and the break area increase with the increase of the impact loading.When the break area decreases abruptly,the crack length increases suddenly,which shows that there is an obvious incubation period of crack forming,and at first some pits appear on the verge of the rock plate and the propagation rate of crack length and break area decrease with the increase of the impact velocity.According to test results,the scope of impact resistance optimized angle is about 15°~30°.