隧道穿越浅埋段沟谷长管棚注浆加固施工技术
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摘要
延安市小砭沟隧道左线穿越约20m宽覆盖层仅有2. 2m厚的沟谷段,且覆盖层含淤泥积水、围岩条件差的情况下,根据现场条件的变化,将洞门施工的超前长管棚支护技术采取梯次扩大断面等措施应用至隧道内通过浅埋段施工,采用长管棚注浆加固措施为主,结合地表注浆外加固和隧道帷幕注浆内加固挤水固结淤泥及碎岩土使围岩形成整体帷幕结构,再根据现场实际情况采用加密小导管二次加固减小钢管间距增加支撑力,最后开挖时采用短掘短支小循环永久支护施工渐次通过。结果表明,通过综合应用技术措施安全顺利通过了含淤泥积水围岩不稳定的浅埋段沟谷,在施工通过后监控测量累计变形量小于8mm,大大小于该浅埋段设计变形量200mm的要求。通过长管棚超前支护在隧道内的应用技术,对顶板有淤泥等不稳定岩土类似地貌施工有较高的参考价值。
The left line of Xiaobiangou tunnel in Yan'an is used to pass through only 2. 2 m thick gully section of about20 m wide overburden layer,and the overburden layer contains silt and stagnant water. In the case of poor surrounding rock condition,according to the change of site conditions,in this paper,the advance long pipe shed supporting technology of tunnel door construction is applied to the construction of shallow buried section in tunnel by using trapezoidal expansion of section and other measures. Long pipe shed grouting reinforcement measures are adopted,with the combination of surface grouting and tunnel curtain grouting, the surrounding rock can be formed into a whole curtain structure, and then according to the actual situation of the field,the reinforcement with small infill ducts is used to reduce the steel pipe spacing and increase the supporting force. At the end of the excavation,the short-distance excavation and short-distance supporting and small circulation permanent support is adopted gradually. The results show that the comprehensive application of technical measures can safely and smoothly pass through the shallow buried gullies which are unstable in the surrounding rock containing silt and stagnant water. After construction,the accumulative deformation is less than 8 mm,which is much smaller than the design deformation of the shallow buried section( 200 mm). The application of long pipe shed advance support in tunnel has a great reference value for the construction in the roof with similar landform.
The left line of Xiaobiangou tunnel in Yan'an is used to pass through only 2. 2 m thick gully section of about20 m wide overburden layer,and the overburden layer contains silt and stagnant water. In the case of poor surrounding rock condition,according to the change of site conditions,in this paper,the advance long pipe shed supporting technology of tunnel door construction is applied to the construction of shallow buried section in tunnel by using trapezoidal expansion of section and other measures. Long pipe shed grouting reinforcement measures are adopted,with the combination of surface grouting and tunnel curtain grouting, the surrounding rock can be formed into a whole curtain structure, and then according to the actual situation of the field,the reinforcement with small infill ducts is used to reduce the steel pipe spacing and increase the supporting force. At the end of the excavation,the short-distance excavation and short-distance supporting and small circulation permanent support is adopted gradually. The results show that the comprehensive application of technical measures can safely and smoothly pass through the shallow buried gullies which are unstable in the surrounding rock containing silt and stagnant water. After construction,the accumulative deformation is less than 8 mm,which is much smaller than the design deformation of the shallow buried section( 200 mm). The application of long pipe shed advance support in tunnel has a great reference value for the construction in the roof with similar landform.
引文
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[2]梅勇文.浅埋隧道塌方冒顶处理方法[J].北方交通,2012(10):97-99.
[3]邹金杰,顾鑫杰,章立峰,等.浅埋暗挖原理在西部某隧道冒顶塌方治理中的应用[J].现代隧道技术,2016,53(2):202-206.
[4]林希鹤,卢清国,马艳春.超前管棚支护在隧道工程中的应用[J].铁道建筑,2006(8):58-60.
[5]张林青.浅谈隧道洞口长管棚施工方法及要点[J].企业技术开挖,2015,34(3):167-172.
[6]高怀棚,毛海东.长管棚预注浆超前支护技术在浅埋偏压大跨隧道洞口施工中的应用[J].公路,2005(10):214-217.
[7]邢厚俊,徐祯祥.大管棚在超浅埋暗挖大跨度隧道工程中的应用[J].岩石力学与工程学报,1999,18(S1):1059-1061.
[8]李明亮,王国体,刘志楠,等.公路隧道浅埋段地表加固分析[J].工程与建设,2011,25(2):248-249.
[9]吕丽敏.岩石基础灌浆技术在水工建设中的应用[J].科技创新与应用,2014(29):194-195.
[10]董国庆,顾训水.帷幕注浆法堵水实例[J].中国高新技术企业,2011(25):82-84.