爆炸荷载对邻近巷道裂纹群影响规律动焦散试验

为了研究围岩中存在缺陷的既有巷道受邻近巷道爆破振动的影响,采用爆炸加载数字激光动态焦散线试验系统,探究了新巷道爆破开挖对邻近巷道预制裂纹群的影响规律。试验结果表明:爆炸荷载对邻近巷道围岩裂纹群的影响规律与裂纹所在位置、裂纹倾角和与邻近巷道间距L有关;当L45 mm或L65 mm时,巷道左壁预制裂纹与炮孔连线区域出现三角形破坏,但表现形式有所差异;当L增大时,巷道周边与应力波相切或有一定夹角的1号、3号和4号裂纹扩展现象均不明显,而其他裂纹扩展位移基本呈逐渐减少趋势;群裂纹扩展时,动态应力强度因子的变化趋势基本呈现先振荡增大到峰值,后减小,然后再增大到第2个峰值,最后振荡减小到0的规律,且当裂纹最终扩展位移越小时,这种现象越明显,伴随着裂纹呈现出扩展—止裂—快速扩展—止裂的扩展规律。

Dynamic caustics test of blast load impact on the group of crack surrounding neighboring roadway

In order to research the influence of blasting vibration from excavation of a new tunnel on closein existed tunnel which contains defects in the surrounding rock，based on digital laser dynamic caustics experimental system which uses explosive to apply the load，the authors explored the expansion laws of the original crack group when the new roadway was excavated by blasting.The experimental results show that the propagation of the cracks surrounding the roadway has something to do with the position of the crack，crack angle and the distance L between blast hole and the center of roadway；When L<45 mm or L>65 mm，it appears the triangle damage on the left side of roadway，but the pattern of manifestation is different.When L increases，the propagation phenomenon of the No.1，No.3 and No.4 cracks are not obvious，the displacement of other cracks extension basically shows a trend of gradually diminution；When the group of crack propagates，the dynamic stress intension factor oscillating increases to peak firstly and then decreases，it increases to second peak again and decreases to zero.And the smaller crack eventually expanding displacement is，the more obvious the phenomenon is，the crack presents the extension rule of extensionthe crack arrestrapid extensioncrack arrest.