摘要
设计室内模型试验,改变模型中既有隧道的围岩级别和衬砌刚度,采用在既有隧道上方挖方的方式,考察挖方过程中既有隧道围岩压力、衬砌变形和结构内力的变化规律,研究既有隧道的承载拱效应。结果表明:衬砌刚度较大时Ⅴ级和Ⅵ级围岩的承载拱外边界分别位于覆跨比1.3～1.6和1.6～2.2范围内,衬砌刚度较小时Ⅴ级和Ⅵ级围岩的承载拱外边界分别位于覆跨比1.6～1.9和1.9～2.5范围内;衬砌刚度越大承载拱范围越小,围岩级别越差承载拱范围越大;在既有深埋隧道上方不断挖方时,会逐渐对承载拱产生影响,使既有隧道经历无影响(覆跨比大于2.9)、弱影响(覆跨比处于1.4～2.9)和强影响(覆跨比小于1.4)3个阶段;既有隧道上方挖方过程中,拱顶相对其他部位受影响最大。研究成果可为类似近接隧道工程的设计和施工提供借鉴与参考。
The indoor model experiment was designed to study the load-bearing arch effect of existing tunnel by excavation above existing tunnel.In the experiment,the variations of surrounding rock pressure,lining deformation and internal force of the existing tunnel during excavation were investigated by changing the level of surrounding rock and lining stiffness.Results show that,when the lining stiffness is large,the outer boundaries of the fifth and sixth grades of the surrounding rock's load-bearing arch are in the range of 1.3~1.6 and 1.6~2.2 of the thickness span ratio respectively.When the lining stiffness is small,the outer boundaries of the fifth and sixth grades of the surrounding rock s load bearing arch are in the range of 1.6~1.9 and 1.9~2.5 of the thickness span ratio respectively.The greater the lining stiffness is,the smaller the load bearing arch range is.The worse the grade of surrounding rock is,the larger the load-bearing arch range is.When excavating continuously above the existing deep-buried tunnel,it will gradually affect the load bearing arch,making the existing tunnel experience three stages:no influence(thickness-span ratio is greater than 2.9),weak influence(thickness-span ratio is 1.4~2.9)and strong influence(thickness-span ratio is less than 1.4).Compared with other parts,the arch crown is most affected in the process of excavating above the existing tunnel.The research results can provide reference to similar approaching tunnel projects in design and construction.
作者
龚伦
马相峰
敖维林
梁振宁
章慧健
仇文革
王希元
GONG Lun;MA Xiangfeng;AO Weilin;LIANG Zhenning;ZHANG Huijian;QIU Wenge;WANG Xiyuan(Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu Sichuan 610031,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu Sichuan 610031,China)
出处
《中国铁道科学》
EI
CAS
CSCD
北大核心
2019年第1期55-62,共8页
China Railway Science
基金
国家重点研发计划(2017YFC0806000)
国家自然科学基金资助项目(51478392
5118399)
关键词
既有隧道
隧道上方挖方
承载拱效应
覆跨比
模型试验
Existing tunnel
Excavation above tunnel
Load-bearing arch effect
Thickness-span ratio
Model test
