摘要
依据已有研究对空孔效应和设置空孔时裂纹扩展规律进行探讨,发现空孔有利于裂纹贯通,对提升爆破效果有一定帮助,但也发现传统的直线型空孔布置会导致裂纹偏向,即在空孔附近转向、偏离原发展路径,影响原设计开挖轮廓。若设置偏位空孔,则可充分利用空孔效应及导向作用以提高开挖质量。对于偏位空孔在爆破中的效应,采用数值模拟研究了不同炮孔间距、空孔偏位角下的裂纹扩展规律和炮孔间贯通情况,探讨了最优偏位角度设计,并根据模拟结果对现场爆破方案进行优化,研究实际应用效果。研究结果表明:偏位空孔对爆生裂纹具有较直线空孔更明显的导向作用,主要表现在爆生裂纹尖端向空孔本身发展或被空孔裂纹引导偏向、最终主裂纹与空孔连通或在空孔范围之外主裂纹相贯通,更利于炮孔主裂纹扩展与贯通;通过提取模拟结果并测量裂纹范围,对于孔间距在60 cm及以下时,适用于周边眼爆破设计的最优偏位角为15°,在此情况下炮孔连线方向形成了与孔心连线相平行的裂纹,能显著提升贯通效果;对于优化后的福厦铁路某隧道爆破施工方案,通过振速监测及超欠挖断面扫描分析,发现周边眼起爆引起的爆破振速降低了超过50%,超欠挖值也由平均25 cm降低至15 cm以内,整体应用效果良好。该项研究可为隧道爆破减振及超欠挖控制研究提供一定参考。
Based on existing research,the effects of the empty hole effect and the law of crack propagation when empty holes are set were investigated and discussed.It has been found that empty hole is beneficial for crack penetration and the improvement of blasting quality.However,the drawback that the traditional linear arrangement would lead to cracks deflection was also found,which means cracks tend to deviate from the original path near an empty hole.The empty hole effect and guiding effect could be fully utilized to improve excavation quality if offset empty holes are set.For the effect of offset holes in blasting,the numerical simulation was adopted to explore the crack propagation law and the penetration under different hole spacing and offset angles,and the optimal offset angle were discussed.According to the simulating result,the scheme was optimized and applied to on-site blasting.Results show that the offset hole has a more obvious guiding effect on blasting cracks than the straight hole,which can be observed from following features:blasting cracks go towards the empty hole directly or are guided to change the original route,and finally the main cracks connect to the empty hole or communicate with the other outside the empty hole.Compared with the traditional straight hole,the offset hole is more conducive to the expansion and penetration of the main crack;When the hole spacing is 60 cm or less,the optimal offset angle for peripheral blasting design is 15°.In this case,the direction of the blast hole line forms a crack parallel to the line of the hole center,which can significantly improve the penetration;According to the results,the blasting parameters of one tunnel on the Fuzhou-Xiamen Railway were optimized.By comparing the blasting vibration velocity before and after the optimization and the scanning of excavation quality,it was found that the blasting vibration velocity is reduced by more than 50%,and the over excavation value is also reduced from an average of 25 cm to less than 15 cm.The application works well.This study can provide a certain reference for the research of tunnel blasting vibration reduction and over-and-under excavation control.
作者
余绍山
王薇
李姚伟奇
YU Shaoshan;WANG Wei;LI Yaoweiqi(Xiamen Public Works Section of Nanchang Railway Bureau,Xiamen 361001,China;School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2024年第4期1509-1520,共12页
Journal of Railway Science and Engineering
基金
中铁四局集团有限公司科技研发项目(2022-30)。
关键词
光面爆破
周边眼
偏位空孔
爆破振速
超欠挖控制
smooth blasting
peripheral hole
offset empty hole
blasting vibration velocity
over and under excavation control
作者简介
通信作者:王薇(1969-),女,湖南醴陵人,副教授,博士,从事隧道及地下工程领域的研究,E−mail:wangweicsu@csu.edu.cn。
