| 深埋大跨度绿泥石片岩隧道变形规律及合理预留变形量 |
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| 引用本文： | 陈丽俊,陈建勋,罗彦斌,刘伟伟,王传武.深埋大跨度绿泥石片岩隧道变形规律及合理预留变形量[J].中国公路学报,2021,34(6):147-157. |
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| 作者姓名： | 陈丽俊 陈建勋 罗彦斌 刘伟伟 王传武 |
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| 作者单位： | 长安大学 公路学院, 陕西 西安 710064 |
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| 基金项目： | 国家自然科学基金项目（41831286，51808049） |
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| 摘 要： | 陕西宝鸡至汉中高速公路连城山隧道（双洞六车道）在穿越绿泥石片岩地层过程中发生了初期支护变形侵限、喷射混凝土开裂、钢架扭曲等严重大变形灾害，施工难度非常大。基于连城山隧道大变形现场调研和现场监控量测数据，统计分析了不同绿泥石片岩岩体状态下的隧道变形情况，研究了深埋大跨度绿泥石片岩隧道变形规律及合理预留变形量；在此基础上建立了深埋大跨度绿泥石片岩隧道施工变形控制基准。研究结果表明：隧道变形量与绿泥石片岩的岩体状态密切相关，绿泥石片岩呈粉末状时隧道变形量最大，绿泥石片岩呈块状或厚层状时隧道变形量相对最小；隧道变形整体上表现出拱部沉降明显大于水平收敛的特征；采用“三台阶留核心土法+拱墙部双层HK200b钢架+φ108大管径锁脚锚管+深仰拱”的施工方案时，粉末状、碎裂状（粉末加块石）、薄层状、块状或厚层状绿泥石片岩段隧道沉降量值分别为358~850，234~678，153~486，27~236 mm；其中以拱部初期支护的整体沉降为主，占总沉降的55.5%~86.1%；隧道沉降主要发生在上台阶和中台阶施工阶段，占总沉降的66.7%~82.7%；仰拱施作后产生的变形占比最小，为3.3%~4.9%。建议在以上4种绿泥石片岩岩体状态下，隧道预留变形量分别取70~95，50~70，30~50，15~30 cm；在保证隧道施工场地的前提下，应尽量缩短台阶长度，减少初期支护封闭成环的时间。
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| 关 键 词： | 隧道工程 绿泥石片岩 预留变形 变形规律 深埋隧道 大跨度 |
| 收稿时间： | 2020-06-03 |
Deformation Law and Reasonable Reserved Deformation of Deep Large-span Chlorite Schist Tunnel |
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| CHEN Li-jun,CHEN Jian-xun,LUO Yan-bin,LIU Wei-wei,WANG Chuan-wu.Deformation Law and Reasonable Reserved Deformation of Deep Large-span Chlorite Schist Tunnel[J].China Journal of Highway and Transport,2021,34(6):147-157. |
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| Authors: | CHEN Li-jun CHEN Jian-xun LUO Yan-bin LIU Wei-wei WANG Chuan-wu |
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| Affiliation: | School of Highway, Chang'an University, Xi'an 710064, Shaanxi, China |
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| Abstract: | The construction of the Lianchengshan Tunnel (double-hole, six-lane) of the Baoji-Hanzhong Expressway in Shaanxi Province, China was extremely difficult because serious deformation disasters, such as the deformation invasion limit of the primary support, shotcrete cracking, and steel frame distortion, occurred in the process of passing through a chlorite schist stratum. Based on the field investigation of the large deformation and monitoring data of the Lianchengshan Tunnel, the tunnel deformation under different rock mass states of chlorite schist was analyzed statistically. The deformation law and reasonable reserved deformation of the deep large-span tunnel in chlorite schist stratum were studied. Based on this analysis, a control standard of construction deformation for deep large-span chlorite schist tunnels was established. The results show that the tunnel deformation is closely related to the rock mass states of chlorite schist. The tunnel deformation is the largest when chlorite schist is powdery and the smallest when chlorite schist is a block or thick layered. The tunnel deformation shows the law that the arch settlement is greater than the horizontal convergence. A construction scheme including a three-step core soil method with a double-layer HK200b steel frame of the tunnel arch, a feet-lock pipe with a diameter of 108 mm, and a deep tunnel invert was adopted. The main ranges of the tunnel settlement are found to be 358-850, 234-678, 153-486, and 27-236 mm, respectively, for chlorite schist that is powdery, cataclastic (powder and block stone), thin layered, and block or thick layered. Most of the tunnel settlement is the overall settlement of the primary support, which accounts for 55.5%-86.1% of the total settlement. The tunnel settlement mainly occurs in the construction stages of the upper and middle steps, accounting for approximately 66.7%-82.7% of the total settlement. After the tunnel invert is constructed, the deformation ratio is the smallest (approximately 3.3%-4.9%). The results suggest that the reasonable reserved deformations of the tunnel under the above mentioned four states of chlorite schist are 70-95, 50-70, 30-50, and 15-30 cm, respectively. In addition, in order to reduce the time for the primary support to be closed into a ring, the step length of the tunnel should be shortened as much as possible on the premise of meeting the needs of the tunnel construction site. |
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| Keywords: | tunnel engineering chlorite schist reserved deformation deformation law deep tunnel large span |
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