爆生裂纹与层理缺陷相互作用的实验研究

An experimental study of the interaction between the blast-induced crack and the bedding defect

为了研究爆生裂纹与层理缺陷的相互作用机制,采用新型数字激光动态焦散线实验方法对含层理岩体在爆炸载荷下的动态断裂行为进行了实验分析。实验结果表明:在爆炸载荷下,当炮孔切槽方向与层理面存在一定夹角θ时,爆炸使层理岩体裂纹扩展分为爆生主裂纹、界面裂纹、次生裂纹三个阶段;爆生主裂纹扩展到层理面后,不是直接贯通层理面沿原方向继续扩展,而是产生界面裂纹之后再继续扩展,产生的界面裂纹长度随夹角θ增大而减小;裂纹扩展贯通层理后,次生裂纹继续扩展,随夹角θ的增大,次生裂纹扩展长度逐渐增大;爆生主裂纹扩展过程中,随着爆生主裂纹尖端至层理面距离的减小,爆生主裂纹尖端动态应力强度因子和裂纹扩展速度均逐渐减小,说明层理面对爆生主裂纹的扩展起阻碍作用,且夹角θ越大阻碍作用越明显。实验研究分析了不同角度层理构造缺陷对裂纹扩展规律的影响。

For studying the interaction between blast-induced cracks and bedding defects, a new digital-laserdynamic caustic system was utilized to investigate the fracture behavior of bedding rock under explosive load. The results shows that, under explosive load, when there is a certain angle θ between the grooving direction of the blast hole and the bedding surface, the crack propagation of the bedding rock is divided into three stages ： the main b last-induced c r a c k , the interface crack, and the secondary crack . After the main blast-induced crack propagates to the bedding surface, rather than passing through the original direction, it causes the initiation of the interface crack before its redevelopment. The length of interface crack decreases with the angle θ . The secondary c ra ck ke ep s on developing after the transversal of the crack propagation in the bedding surface. With the increase of θ, the extended distance of the secondary c ra ck rises gradually. During the main blast-induced crack propagation, the crack propagating velocity and the dynamic stress intensity factor （DSIF） of the crack tip decline gradually with the decrease of the distance between the bedding surface and the main crack tip, indicating that bedding surface has a resistant effect on the main blast-induced crack propagation and the effect is stronger with the increase of the angle θ .