爆炸动载荷下裂纹扩展规律的实验研究

 为研究在爆炸动载荷作用下岩石内裂纹的起裂及扩展规律，应用PMMA材料制作带裂纹平板试样，在距离裂纹尖端60 mm的圆周上设置与裂纹成不同角度的炮孔，然后引爆雷管来实验研究裂纹的动态起裂及其扩展规律，系统地研究爆炸应力波入射角对裂纹起裂角和扩展角的影响规律。实验结果表明，入射角为0°时，起裂角为0°，即裂纹沿原裂纹面扩展；当入射角大于15°而小于75°时，在裂纹的两端会产生翼型裂纹，其翼型裂纹的起裂角及扩展长度都与入射角有关；当入射角大于75°时，新生裂纹很小。

EXPERIMENTAL STUDY OF REGULARITY OF CRACK PROPAGATION UNDER BLASTING DYNAMIC LOADS

In order to investigate the regularity of crack propagation under blasting dynamic loads，polymethyl methacrylate(PMMA) plates are employed to make samples containing a single crack and a borehole. The borehole is designed along the quadrant of a circle centered at one crack tip with radius of 60 mm. A detonator inside the borehole is fired to produce dynamic stress waves. The effects of incident angles of stress waves on crack initiation angles and propagation angles have been studied experimentally. The results show that：(1) As incident angle is 0°，crack initiation angle is 0°，i.e. the cracks propagate along the crack surface plane；(2) As incident angle is greater than 15° and less than 75°，wing-cracks occur along the pre-existing crack tips；(3) The wing-crack property is related to the incident angle of stress waves；(4) As incident angle is greater than 75°，new developed cracks are very small.