爆炸加载下混凝土表面的裂纹扩展

External crack propagation of concrete surface under explosive loading

为深入研究内爆加载下岩土类材料的破坏机理,提出了一种新的爆炸裂纹检测算法,采用数字图像相关方法测量表面位移场和应变场,建立了裂纹扩展和扩张模型,并通过混凝土内爆试验观测裂纹扩展过程,研究了裂纹长度扩展与宽度扩张规律。结果表明,裂纹长度扩展是应力波和爆生气体共同作用的结果,裂纹最大扩展速度为225.95 m/s,平均速度为122.27 m/s,裂纹总长159.92 mm,长度扩展止于1.75 ms;裂纹的张开由气体主导,最大宽度1.59 mm,作用时间长达4.5 ms;拉应变集中区先于裂纹出现,其形状决定了裂纹的走向和趋势,爆炸加载下断裂过程区长度为骨料粒径的8~9倍。

To further investigate the failure mechanism of geotechnical materials under implosion loading, a novel blasting crack detection algorithm is proposed in this paper, the digital image correlation method is used to measure the surface displacement field and strain field, the crack propagation and expansion model is built. A concrete blasting experiment was carried out, the crack propagation and expansion process were measured and analyzed. The results show that the propagation of crack is a combined action of stress wave and explosive products. The maximum velocity is 225.95 m/s, the average velocity is 122.27 m/s, the total length is 159.92 mm, and the length propagation ceases at 1.75 ms. The opening of the crack is dominated by explosive products with a maximum width of 1.59 mm. The action time of explosive products is 4.5 ms. The tensile strain concentration zone appears before the initiation of crack and its shape determines the tendency of the crack. The fracture process zone is about 8-9 times of the maximum aggregate size.