双层周边孔护壁爆破在软弱破碎围岩的应用研究  

Application of Casing Pipe Charge and Double-layer Perimeter Holes on Controlled Contour Blasting in Soft Fractured Surrounding Rock

作　　者：黄志强 崔正宇 刘夺 杨幸福 HUANG Zhi-qiang;CUI Zheng-yu;LIU Duo;YANG Xing-fu(College of Architecture and Civil Engineering,Shenyang University of Technology,Shenyang 110870,China;China Jiaotong Road and Bridge North Engineering Co.,Ltd.,Beijing 100024,China)

机构地区：[1]沈阳工业大学建筑与土木工程学院,沈阳110870 [2]中交路桥北方工程有限公司,北京100024

出　　处：《爆破》2022年第1期75-82,共8页Blasting

基　　金：国家自然科学基金(42007241)。

摘　　要：软弱破碎围岩在传统光面爆破施工中,容易出现超欠挖量难以控制、围岩损伤程度严重、半孔保存率低等一系列问题。以贵州小白岩隧道爆破施工为工程背景,研究了双层周边孔护壁爆破设计在软弱破碎围岩爆破工程中的应用。研究从分析超欠挖现象的形成原因出发,在周边孔炮孔布置、装药结构以及爆破顺序等方面进行了优化,将最外层的辅助孔装药结构调整为与周边孔相同的不耦合装药,并在外层周边孔保留岩体的一侧添加护壁,爆破时先起爆外层周边孔再起爆内层周边孔。通过数值模拟及现场试验,确定了双层周边孔环向间距为500 mm,径向间距为650 mm,内外层起爆间隔为50 ms。在应用双层周边眼护壁爆破设计后,现场试验段的超挖量与常规光面爆破相比减少了40%~60%,半孔保存率提升至89%,每循环进尺炸药使用量节约了22 kg,经济效益显著提升,具有一定的推广应用价值。In traditional smooth blasting construction,soft cracked surrounding rock is prone to a series problems,such as difficulty to control the amount of overcutting and undercutting,serious damage of surrounding rock,and low half-hole preservation rate.Based on the blasting construction of Xiaobaiyan tunnel in Guizhou Province,a casing pipe charge blasting design with double-layer perimeter holes was designed for soft fractured surrounding rock.In this study,starting from the causes of overbreak and underbreak,the perimeter hole layout,charge structure and blasting sequence were optimized.The charge structure of the outermost auxiliary holes was adjusted to the same uncoupled charge as that of the perimeter holes,and a protection casing pipe was added to the side of the reserved rock mass in each perimeter hole.The perimeter holes in were designed to initiate first and then followed by the inner layers of holes.Through numerical simulation and field tests,it is determined that the circumferential spacing of the double-layer perimeter holes is 500 mm,and the radial spacing is 650 mm.The initiation delay interval of the inner and outer layers is 50 ms.After applying the presented blasting design,the amount of over-excavation in the field test section has been reduced by 40%to 60%compared with conventional smooth blasting,and the half-hole preservation rate has increased to 89%.Finally,22 kg explosive consumption is saved per cycle advance and the economic benefit is significantly improved,which has a good popularization and application value.

关 键 词：隧道爆破 双层周边孔 护壁 软弱破碎围岩 

分 类 号：U455.6[建筑科学—桥梁与隧道工程]