摘要
大跨度黄土隧道施工时易产生地表开裂、沉降变形、支护侵限、塌方等现象,建设难度极大。以目前世界上开挖跨度最大的高速公路黄土隧道——墩梁隧道为工程依托,采用现场实测、理论分析和数值模拟相结合的方法,通过对大跨度黄土公路隧道变形规律进行分析,结合单洞两车道黄土隧道支护设计相关研究成果和工程实践经验,提出大跨度黄土隧道初期支护结构型式,并对其结构受力和稳定性开展研究。研究表明:采用三台阶法施工时,上台阶处收敛经历4个阶段,最大开挖线处收敛经历3个阶段。上台阶处收敛速率比最大开挖线处的收敛速率快,最大开挖线处的最终收敛值约为上台阶处的3倍左右。沉降曲线随着与掌子面距离增大,沉降值持续增大,增速放缓。距掌子面1D、1D～2D、2D～3D和3D～4D范围内,各测点产生的沉降值分别为最大沉降值的49%、23%、12%和6%。大跨度黄土隧道采用"钢架+喷射混凝土+钢筋网+锁脚锚杆(管)+纵向连接筋"组合结构能够满足隧道结构稳定。提出洞口段施工采用双侧壁导坑法,洞身段施工采用三台阶留核心土法,浅埋段地基承载力较低的隧底采用钢管注浆加固的大跨度黄土隧道稳定控制技术。
During the construction of large-span loess tunnel,surface cracking,settlement deformation,support invasion and landslides are easy to occur,which makes the construction of large-span loess tunnel extremely difficult.Based on the pier-beam tunnel,the largest-span highway loess tunnel excavated in the world at present,the combination of field measurement,theoretical analysis and numerical simulation was used to analyze the deformation lawof large-span loess highway tunnel.Combined with the relevant research results and engineering practice experience of support design of single loess tunnel and two-lane loess tunnel,the structure type of the initial support was put forward,and structural force and stability of initial support were studied.The results showed that the convergence at the upper step and the maximum excavation line could be divided into four stages when the three-step method was adopted.The convergence rate at the upper step was faster than that at the maximum excavation line,and the final convergence value at the maximum excavation line was about three times of that at the upper step.As the distance between the settlement curve and the face increases,the settlement value increased continuously and the growth rate slowed down.Within the range of 1D,1D to 2D,2D to 3D and 3D to 4D from the palm surface,the settlement values generated by each measuring point were 49%,23%,12%and 6%of the maximum settlement values,respectively.The large-span loess tunnel colud ensure the stability of the tunnel structure by adopting the composite structure of'steel frame+shotcrete+steel mesh+anchor bolt(pipe)+longitudinal connection bar'.The double-sided guide pit method was adopted in the construction of the tunnel entrance section,the three-step retaining core soil method in the construction of the tunnel body section,and the stability control technology of the large-span loess tunnel strengthened by steel pipe grouting was adopted in the tunnel bottom with lowbearing capacity in the shallowsection.
作者
陈建勋
罗彦斌
CHEN Jianxun;LUO Yanbin(Key Laboratory for Bridge and Tunnel of Shaanxi Province,School of Highway Engineering,Changan University,Xi'an 710064,Shaanxi,China)
出处
《隧道与地下工程灾害防治》
2019年第1期81-89,共9页
Hazard Control in Tunnelling and Underground Engineering
基金
国家重点研发计划子题(2016YFC0802202)
长江学者计划(T2014214)
中国博士后科学基金(2016M602738)
陕西省自然科学基础研究计划项目(2017JM5051)
国家自然科学基金项目(51108034
51408054
51678063)
关键词
隧道工程
大跨度黄土隧道
变形规律
结构稳定性
控制技术
tunnel engineering
lager span loess tunnel
deformation rule
stability of tunnel structure
control technology
作者简介
陈建勋(1969—),男,陕西韩城人,博士,教授,博士生导师,长江学者特聘教授,主要研究方向为隧道工程.E-mail:chenjx1969@163.com
