挤压性围岩大跨隧道施工工法优化
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摘要
以兰渝铁路新城子隧道为例,通过现场测试和FLAC 3D数值模拟,对挤压性围岩大跨隧道采用双侧壁导坑法2种不同开挖顺序时的隧道变形和衬砌受力进行对比分析。结果表明:采用双侧壁导坑法按常规顺序开挖导洞1～9比依次分层开挖上、中、下各导洞更有利于控制隧道变形,且二次衬砌受力明显较小;挤压性围岩隧道施工中相邻导洞贯通形成扁平洞室会导致大变形,施工中应尽量避免;2种开挖顺序隧道水平收敛均大于拱顶沉降,必要时可加强临时支护。
Taking Xinchengzi tunnel of Lanzhou-Chongqing railway as an example, the tunnel deformation and lining stress in two different excavation order by double side leading method were analyzed for the large span tunnel in squeezing surrounding rock.The results show that excavation of No.1 to No.9 pilot tunnel in regular order by double side leading method could control the tunnel deformation better than excavation of upper,middle and lower pilot tunnel successively, the stress of the secondary lining is obviously small.Adjacent pilot tunnels are connected to form a flat cavern and could lead to large deformation during construction of squeezing surrounding rock tunnel,which should be avoided as far as possible.Horizontal convergence of tunnel is greater than vault subsidence in two kinds of excavation order,and temporary support can be strengthened when necessary.
Taking Xinchengzi tunnel of Lanzhou-Chongqing railway as an example, the tunnel deformation and lining stress in two different excavation order by double side leading method were analyzed for the large span tunnel in squeezing surrounding rock.The results show that excavation of No.1 to No.9 pilot tunnel in regular order by double side leading method could control the tunnel deformation better than excavation of upper,middle and lower pilot tunnel successively, the stress of the secondary lining is obviously small.Adjacent pilot tunnels are connected to form a flat cavern and could lead to large deformation during construction of squeezing surrounding rock tunnel,which should be avoided as far as possible.Horizontal convergence of tunnel is greater than vault subsidence in two kinds of excavation order,and temporary support can be strengthened when necessary.
引文
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[3]周丁恒,曲海锋,蔡永昌,等.特大断面大跨度隧道围岩变形的现场试验研究[J].岩石力学与工程学报,2009,28(9):1773-1782.
[4]李文江,贾晓云,刘志春.地铁区间大断面隧道施工力学行为研究[J].地下空间与工程学报,2007,3(1):40-43.
[5]张新亮.大断面隧道CD法施工围岩应力行为研究[D].成都:西南交通大学,2008.
[6]谢旭强,王玉富.大跨隧道双侧壁导坑法施工力学行为研究[J].北方交通,2008,31(7):146-149.
[7]谭忠盛,孟德鑫,石新栋,等.大跨小间距黄土隧道支护体系及施工方法研究[J].中国公路学报,2015,28(11):82-89.
[8]甘腾飞,黄世政,崔青玉.大断面地铁渡线隧道开挖工法优化研究[J].路基工程,2016,34(3):191-196.
[9]汪伟.高地应力软岩隧道连拱大跨段施工技术[J].铁道建筑技术,2014,31(增1):148-151,179.
[10]胡小银.高地应力软岩隧道大跨连拱过渡段施工技术研究[J].铁道建筑技术,2017,34(5):64-67,72.
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