隧道拱部穿越页岩爆破开挖方法及参数试验研究  

Blasting excavation method and parametric tests for tunnel arch crossing shale

作　　者：张万志 徐帮树[2] 葛颜慧[1] 梅洁 朱永学[3] 王丙坤[3] ZHANG Wanzhi;XU Bangshu;GE Yanhui;MEI Jie;ZHU Yongxue;WANG Bingkun(School of Transportation and Civil Engineering,Shandong Jiaotong University,Jinan 250357,China;Geotechnical and Structural Engineering,Research Center,Shandong University,Jinan 250061,China;China Railway Tunnel Group No.2 Co.,Ltd.,Langfang 065201,China)

机构地区：[1]山东交通学院交通土建工程学院,济南250357 [2]山东大学岩土与结构工程研究中心,济南250061 [3]中铁隧道集团二处有限公司,河北廊坊065201

出　　处：《振动与冲击》2022年第15期90-98,共9页Journal of Vibration and Shock

基　　金：国家自然科学基金(41302225);山东省自然科学基金(ZR2021QE246);山东交通学院基金(50004955)。

摘　　要：隧道拱部穿越页岩存在上软下硬的围岩分布特征,爆破开挖拱部常发生大体积岩体掉块、塌落的问题。依托海螺峪隧道工程,应用爆破开挖试验和数值模拟的方法,分析拱部页岩的破坏特征,提出了上软下硬岩体隧道上台阶CD(center diaphragm)开挖方法。并优化了光爆层炮孔及装药参数、掏槽布孔形式和减小最大单孔装药量等措施。对比分析隧道开挖的围岩破坏特征、超挖大小和围岩变形结果,采用优化的爆破开挖方案围岩轮廓成型的质量更好。结果表明:隧道拱部穿越页岩的爆破开挖,拱顶页岩沿结构面易发生自下而上的逐层脱离破坏,拱肩至拱腰页岩沿结构面易发生张裂破坏。采用上台阶CD开挖方法有利于减小一次开挖面积和约束拱顶页岩分离,采用优化的爆破参数可减小围岩损伤,爆后轮廓不规则边长由0.9 m减小为0.4 m。优化后毛洞的最大线性超挖和平均超挖面积大大减小。表现为:最大线性超挖拱顶由100.2 cm减小为28.6 cm、拱肩由50.1 cm减小为20.1 cm,断面平均超挖面积减小约48.2%;优化后围岩累计变形减小,左、右导洞拱顶最大沉降分别减小47.8%和34.9%,拱腰水平收敛值减小33.3%;下台阶开挖对上台阶拱顶沉降增幅左、右导洞分别减小7.6%和6.2%,拱腰水平收敛增幅减小3.1%。There are distribution characteristics of soft surrounding rock at top and hard one at bottom when tunnel arch passing through shale.In arch of blasting excavation,problems of large volume rock block falling and collapse often occur.Here,based on Hailuoyu tunnel project,failure characteristics of arch shale were analyzed by using blasting excavation tests and numerical simulation,and the center diaphragm(CD)excavation method for upper bench of tunnel in upper soft and lower hard rock body was proposed.Blasting holes and charge parameters of smooth blasting layer,the form of cutting and hole layout and measures to reduce the maximum charge of single hole were optimized.By contrastively analyzing surrounding rock failure characteristics,over excavation size and surrounding rock deformation results of tunnel excavation,the quality of surrounding rock contour forming is better by using the optimized blasting excavation scheme.The results showed that adopting blasting excavation of tunnel arch passing through shale,arch top shale is easy to have layer by layer separation failure from lower to upper along structural plane,and arch shoulder to arch waist shale is easy to have tensile failure along structural plane;the CD excavation method of upper bench is conducive to reduce primary excavation area and restrict separation of arch roof shale;damage of surrounding rock can be reduced by using optimized blasting parameters;irregular contour and side length after blasting can be reduced from 0.9 m to 0.4 m;after optimization,the maximum linear overbreak and average overbreak areas of unlined tunnel are greatly reduced,the maximum linear overbreak vault is reduced from 100.2 cm to 28.6 cm,arch shoulder is reduced from 50.1 cm to 20.1 cm,and the average overbreak area of cross-section is reduced by about 48.2%;after optimization,cumulative deformation of surrounding rock is reduced,the maximum settlements of left and right pilot tunnels’arch tops are reduced by 47.8%and 34.9%,respectively,and the horizontal convergence val

关 键 词：大断面隧道 页岩 爆破开挖 超挖 爆破参数优化 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]