Mechanism and control method of large deformation for large-span chlorite schist tunnel
-
摘要: 依托宝鸡至汉中高速公路连城山隧道(双洞六车道),基于隧道变形和支护结构受力现场测试,分析了大跨度绿泥石片岩隧道大变形灾害特征和机理,总结了隧道大变形灾害综合控制方法,建立了大跨度绿泥石片岩隧道大变形分级标准,提出了各变形级别对应的支护参数。分析结果表明:大跨度绿泥石片岩隧道在开挖过程中以沉降变形为主,主要表现为拱部初期支护的整体沉降;在初期支护闭合后,主要表现为边墙的挤出变形和墙脚下沉引起的仰拱底鼓;大变形灾害主要表现为掌子面失稳垮塌、初期支护变形侵限破坏、锁脚锚管脱焊失效、二次衬砌开裂、边墙下沉以及仰拱回填隆起开裂;绿泥石片岩极其软弱、破碎及仰拱基底遇水软化,是造成隧道大变形灾害的根本原因;隧道开挖跨度大(最大开挖跨度为19.6 m)、断面扁平、拱脚地基承载力不足而缺乏有效约束,加剧了隧道支护变形侵限和失稳破坏;初期支护承载能力有限,围岩荷载不断传递至二次衬砌,是导致二次衬砌开裂的直接原因;围岩变形机制为拱部岩体黏聚力难以克服自重而产生不断向下的滑移和松动机制,以及墙脚和仰拱部位围岩低强度应力比引起的软岩塑性流动机制;通过采用“三台阶留核心土法+大预留+双层HK200b钢架分次支护+大直径锁脚锚管+围岩径向注浆+加深仰拱”的大变形灾害综合控制方法,同时对隧道大变形进行分级管理,有效避免了隧道大变形灾害的发生。Abstract: Based on the field test of deformations and stresses of supporting structures in the Lianchengshan Tunnel of Baoji-Hanzhong Expressway (double-hole six-lane), the characteristics and mechanism of large deformation disasters of large-span chlorite schist tunnels were analyzed, the comprehensive control method of large deformation disasters of the tunnel was summarized, the classification standard of large deformation of large-span chlorite schist tunnel was established, and the corresponding support parameters of each deformation grade were proposed. Analysis result shows that the large-span chlorite schist tunnel mainly has the settlement deformation during the tunnel excavation, which is mainly manifested as the overall settlement of the primary support. After the primary support is closed, the tunnel deformation is mainly manifested by the extrusion deformation of the side wall and the bottom heave of tunnel invert caused by the settlement of tunnel foot. The large deformation disasters are mainly as follows: the instability and collapse of tunnel face, primary support invasion and failure, the unsoldering and failure of feet-lock pipe, the cracking of secondary lining, the sinking of side wall, and the uplift and cracking of invert backfill. The chlorite schist is extremely weak and broken, and the invert base is softened by water, which are the fundamental causes of large deformation disaster of the tunnel. The large span of tunnel excavation (the maximum excavation span is 19.6 m), the flat tunnel section, and the lack of bearing capacity and effective restraint for arch foot foundation aggravate the deformation intrusion and instability failure of tunnel structure. The limited bearing capacity of primary support, causing loads to be continuously transmitted to the secondary lining, is the direct cause of the cracking of secondary lining. The deformation mechanism of surrounding rock can be summarized as the continuous downward slipping and loosening mechanism caused by the difficulty of the cohesion of arch rock mass in overcoming its own weight, and the plastic flow mechanism of soft rock caused by the low-strength stress ratio at the tunnel foot and invert. The large deformation disaster of the tunnel can be effectively avoided by adopting the comprehensive control method of "three-step core soil method+large reservation deformation+double-layer HK200b steel frame+large-diameter feet-lock pipe+radial grouting of surrounding rock+deepening tunnel invert", and managing the large deformation hierarchically at the same time. 5 tabs, 18 figs, 32 refs.
-
Key words:
- tunnel engineering /
- soft rock /
- large-span tunnel /
- deformation mechanism /
- control method
-
表 1 不同岩体状态下绿泥石片岩隧道预留变形量
Table 1. Reserved deformations of chlorite schist tunnel in different rock mass conditions
岩体状态 粉末或散体状 碎裂状(粉末加块石) 薄层或碎裂状 厚层或块状 实测沉降/cm 36~89 23~68 15~49 3~24 建议预留变形量/cm 70~95 50~70 30~50 15~30 表 2 不同施工方案实施效果综合对比
Table 2. Comprehensive comparison of implementation effects of different construction schemes
方案 施工安全性 工艺复杂程度 每延米造价/万元 变形控制效果 结构安全性 月进尺/m 一 拆换拱安全风险高 很复杂(需拆换拱、二次扩挖和出渣) 22.37 临时应力释放层变形不可控 安全 25.0 二 安全 较复杂 19.57 变形可控 安全 38.4 表 3 ϕ108锁脚锚管施作前、后隧道初期支护沉降速率
Table 3. Settlement rates of primary support before and after installation of ϕ108 feet-lock pipe
桩号 隧道平均沉降速率/(mm·d-1) 沉降速率相对变化量/% 锁脚锚管施作前 锁脚锚管施作后 ZK197+045 31.3 7.2 77.0 ZK197+054 42.4 9.6 77.4 ZK197+060 25.0 5.1 81.6 表 4 大跨度绿泥石片岩隧道大变形分级标准
Table 4. Classification standard of large deformation for large-span chlorite schist tunnel
大变形级别 极严重 严重 中等 轻微 岩体特征 粉末状(散体状,极破碎,Kv≤0.15) 碎裂状(粉末加块石,0.15 < Kv≤0.35) 破碎薄层状(0.35 < Kv≤0.55,d≤10 cm) 破碎厚层状(或块状,0.55 < Kv≤0.75,d>10 cm) 支护受力特征 喷射混凝土大面积严重开裂、掉块,大范围钢架扭曲变形,大范围锁脚锚管端部脱焊 喷射混凝土严重开裂、掉块,钢架扭曲变形严重,大范围锁脚锚管端部脱焊 局部喷射混凝土严重开裂,局部钢架扭曲变形,部分锁脚锚管端部脱焊 喷射混凝土在钢架接头部位开裂、剥落,局部钢架扭曲变形 早期变形速率/(cm·d-1) 大于10 5~10 3~5 1~3 岩体变形模量/MPa 小于20 20~35 35~60 60~150 岩体强度 C=100~150 kPa,φ=28°~33° RC<5 MPa RC=5~15 MPa RC=15~25 MPa 预估变形量/cm 大于80 50~80 30~50 15~30 表 5 大跨度绿泥石片岩隧道各变形级别对应的支护参数
Table 5. Supporting parameters of large-span chlorite schist tunnel with different deformation levels
大变形级别 轻微 中等 严重 极严重 预留变形量/cm 15~30 30~50 50~70 70~95 超前小导管 类型 单排 单排或双排 双排 直径/mm 50 长度/m 3.5 钢架 类型 单层HK200b 双层HK200b 间距/cm 80 70~80 60~70 50~60 喷射混凝土 强度等级 C25 厚度/cm 28 56(拱墙),28(仰拱) 56(拱墙),28(仰拱) 56(拱墙),28(仰拱) 径向注浆 必要时采用 必要时采用 采用 小直径锁脚锚管 直径/mm 50 长度/m 4 数量/根 16 24 28 28 大直径锁脚锚管 直径/mm 89 108 长度/m 6 数量/根 4(每2榀钢架) 4(每1榀钢架) 仰拱开挖深度/m 3.61 仰拱回填类型 C20素混凝土 二次衬砌 强度等级 C35 环向钢筋直径/mm 28 环向钢筋间距/cm 20 纵向钢筋直径/mm 12 28 厚度/cm 80(拱墙),100(仰拱) -
[1] 周辉, 李震, 张传庆, 等. 水岩作用下绿泥石片岩的试验研究[C]//雅砻江流域水电开发有限公司. 雅砻江虚拟研究中心2014年度学术年会论文集. 成都: 雅砻江流域水电开发有限公司, 2014: 152-159.ZHOU Hui, LI Zhen, ZHANG Chuan-qing, et al. Experimental Study of chlorite schist under water-rock action[C]//Yalong River Basin Hydropower Development Co., Ltd. Proceedings of the 2014 Annual Academic Conference of Yalong River Virtual Research Center. Chengdu: Yalong River Basin Hydropower Development Co., Ltd., 2014: 152-159. (in Chinese) [2] 刘宁, 张传庆, 褚卫江, 等. 深埋绿泥石片岩变形特征及稳定性分析[J]. 岩石力学与工程学报, 2013, 32(10): 2045-2052. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX201310014.htmLIU Ning, ZHANG Chuan-qing, CHU Wei-jiang, et al. Deformation behavior and stability analysis of deep chlorite schist[J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32(10): 2045-2052. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX201310014.htm [3] 吴忠明, 沈亚兴, 李数林, 等. 锦屏二级水电站1号引水隧洞绿泥石片岩洞段监测成果初步分析[J]. 大坝与安全, 2014(4): 37-42, 48. doi: 10.3969/j.issn.1671-1092.2014.04.007WU Zhong-ming, SHEN Ya-xing, LI Shu-lin, et al. Data analysis on chlorite schist tunnel section of the diversion tunnel No. 1 of Jinping Ⅱ Hydropower Station[J]. Dam and Safety, 2014(4): 37-42, 48. (in Chinese) doi: 10.3969/j.issn.1671-1092.2014.04.007 [4] 周春宏. 深埋条件下绿泥石片岩洞段的变形特征[J]. 科技通报, 2015, 31(3): 108-111. doi: 10.3969/j.issn.1001-7119.2015.03.026ZHOU Chun-hong. Deformation characteristics of chlorite schist tunnel section under deep buried condition[J]. Bulletin of Science and Technology, 2015, 31(3): 108-111. (in Chinese) doi: 10.3969/j.issn.1001-7119.2015.03.026 [5] ZHANG Chuan-qing, CUI Guo-jian, ZHANG Yang, et al. Squeezing deformation control during bench excavation for the Jinping deep soft-rock tunnel[J]. Engineering Failure Analysis, 2020, 116: 104761. doi: 10.1016/j.engfailanal.2020.104761 [6] ZHOU Hui, ZHANG Chuan-qing, LI Zhen, et al. Analysis of mechanical behavior of soft rocks and stability control in deep tunnels[J]. Journal of Rock Mechanics and Geotechnical Engineering, 2014, 6(3): 219-226. doi: 10.1016/j.jrmge.2014.03.003 [7] YANG Fan-jie, ZHANG Chuan-qing, ZHOU Hui, et al. The long-term safety of a deeply buried soft rock tunnel lining under inside-to-outside seepage conditions[J]. Tunnelling and Underground Space Technology, 2017, 67: 132-146. doi: 10.1016/j.tust.2017.05.004 [8] 李震, 周辉, 宋雨泽, 等. 考虑硬化软化和剪胀特性的绿泥石片岩力学模型[J]. 岩土力学, 2013, 34(2): 404-410. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201302017.htmLI Zhen, ZHOU Hui, SONG Yu-ze, et al. Mechanical model of chlorite schist considering hardening-softening and dilatancy characteristics[J]. Rock and Soil Mechanics, 2013, 34(2): 404-410. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201302017.htm [9] 李震, 刘尚各, 于建新, 等. 考虑弹塑性损伤耦合的绿泥石片岩力学模型研究[J]. 地下空间与工程学报, 2017, 13(1): 101-107. https://www.cnki.com.cn/Article/CJFDTOTAL-BASE201701015.htmLI Zhen, LIU Shang-ge, YU Jian-xin, et al. Study on mechanical model of chlorite schist considering elastoplastic damage coupling[J]. Chinese Journal of Underground Space and Engineering, 2017, 13(1): 101-107. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-BASE201701015.htm [10] 于德海, 彭建兵. 三轴压缩下水影响绿泥石片岩力学性质试验研究[J]. 岩石力学与工程学报, 2009, 28(1): 205-211. doi: 10.3321/j.issn:1000-6915.2009.01.027YU De-hai, PENG Jian-bing. Experimental study of mechanical properties of chlorite schist with water under triaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering, 2009, 28(1): 205-211. (in Chinese) doi: 10.3321/j.issn:1000-6915.2009.01.027 [11] GOEL R K, JETHWA J L, PAITHANKAR A G. Tunnelling through the young Himalayas—a case history of the Maneri-Uttarkashi Power Tunnel[J]. Engineering Geology, 1995, 39(1): 31-44. http://www.sciencedirect.com/science/article/pii/001379529400002J [12] 徐则民, 黄润秋, 张倬元, 等. 软岩向深埋隧道的流动[J]. 铁道工程学报, 2000(2): 73-76. doi: 10.3969/j.issn.1006-2106.2000.02.018XU Ze-min, HUANG Run-qiu, ZHANG Zhuo-yuan, et al. Soft rocks flowing toward deep tunnel[J]. Journal of Railway Engineering Society, 2000(2): 73-76. (in Chinese) doi: 10.3969/j.issn.1006-2106.2000.02.018 [13] 高美奔, 李天斌, 孟陆波, 等. 隧道软岩大变形力学机制及防治措施综述[J]. 施工技术, 2013, 42(增): 247-251. https://www.cnki.com.cn/Article/CJFDTOTAL-SGJS2013S2072.htmGAO Mei-ben, LI Tian-bin, MENG Lu-bo, et al. Large deformation of soft rock tunnel large deformation mechanics and prevention measures[J]. Construction Technology, 2013, 42(S): 247-251. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-SGJS2013S2072.htm [14] 李磊, 谭忠盛. 挤压性破碎软岩隧道大变形特征及机制研究[J]. 岩石力学与工程学报, 2018, 37(增1): 3593-3603. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX2018S1051.htmLI Lei, TAN Zhong-sheng. Characteristic and mechanism research for large deformation problem in squeezing-shattered soft rock tunnel[J]. Chinese Journal of Rock Mechanics and Engineering, 2018, 37(S1): 3593-3603. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX2018S1051.htm [15] 杨进忠, 杨培洲, 曾雄辉, 等. 锦屏二级水电站1#引水隧洞绿泥石片岩洞段处理技术与应用[J]. 水利水电技术, 2015, 46(4): 87-92. doi: 10.3969/j.issn.1000-0860.2015.04.020YANG Jin-zhong, YANG Pei-zhou, ZENG Xiong-hui, et al. Technology for treatment of chlorite schist section in No. 1 diversion tunnel of Jinping Ⅱ Hydropower Station and its application[J]. Water Resources and Hydropower Engineering, 2015, 46(4): 87-92. (in Chinese) doi: 10.3969/j.issn.1000-0860.2015.04.020 [16] 王小林, 黄彦波. 中外高地应力软岩隧道大变形工程技术措施对比分析——以兰渝铁路木寨岭隧道与瑞士圣哥达基线隧道为例[J]. 隧道建设, 2018, 38(10): 1621-1629. doi: 10.3973/j.issn.2096-4498.2018.10.004WANG Xiao-lin, HUANG Yan-bo. Comparison of large deformation control technologies for soft rock tunnel with high ground stress between China and foreign countries: a case study of Muzhailing Tunnel on Lanzhou-Chongqing Railway in China and Saint Gotthard Base Tunnel in Switzerland[J]. Tunnel Construction, 2018, 38(10): 1621-1629. (in Chinese) doi: 10.3973/j.issn.2096-4498.2018.10.004 [17] 关宝树. 软弱围岩隧道变形及其控制技术[J]. 隧道建设, 2011, 31(1): 1-17. https://www.cnki.com.cn/Article/CJFDTOTAL-JSSD201101002.htmGUAN Bao-shu. Deformation of tunnels with soft surrounding rocks and its control[J]. Tunnel Construction, 2011, 31(1): 1-17. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-JSSD201101002.htm [18] 张聪, 阳军生, 谢亦朋, 等. 非均质软弱围岩隧道注浆加固圈分布特性[J]. 交通运输工程学报, 2019, 19(3): 58-70. doi: 10.3969/j.issn.1671-1637.2019.03.007ZHANG Cong, YANG Jun-sheng, XIE Yi-peng, et al. Distribution characteristics of grouting reinforcement ring for tunnel with heterogeneous weak surrounding rock[J]. Journal of Traffic and Transportation Engineering, 2019, 19(3): 58-70. (in Chinese) doi: 10.3969/j.issn.1671-1637.2019.03.007 [19] 于天赐. 软岩隧道大变形控制技术研究[J]. 土木工程学报, 2017, 50(S2): 112-117. https://www.cnki.com.cn/Article/CJFDTOTAL-TMGC2017S2018.htmYU Tian-ci. Study on large deformation control technology of tunnel in soft rock[J]. China Civil Engineering Journal, 2017, 50(S2): 112-117. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-TMGC2017S2018.htm [20] 陶志刚, 罗森林, 李梦楠, 等. 层状板岩隧道大变形控制参数优化数值模拟分析及现场试验[J]. 岩石力学与工程学报, 2020, 39(3): 491-506. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX202003006.htmTAO Zhi-gang, LUO Sen-lin, LI Meng-nan, et al. Optimization of large deformation control parameters of layered slate tunnels based on numerical simulation and field test[J]. Chinese Journal of Rock Mechanics and Engineering, 2020, 39(3): 491-506. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX202003006.htm [21] 陈建勋, 罗彦斌. 大跨度黄土公路隧道结构稳定性及控制技术研究[J]. 隧道与地下工程灾害防治, 2019, 1(1): 93-101. https://www.cnki.com.cn/Article/CJFDTOTAL-SDZH201901011.htmCHEN Jian-xun, LUO Yan-bin. The stability of structure and its control technology for large-span loess tunnel[J]. Hazard Control in Tunnelling and Underground Engineering, 2019, 1(1): 93-101. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-SDZH201901011.htm [22] 刘学增, 罗仁立. 大跨度公路隧道围岩竖向压力分布特征探讨[J]. 同济大学学报(自然科学版), 2010, 38(12): 1741-1745. doi: 10.3969/j.issn.0253-374x.2010.12.005LIU Xue-zeng, LUO Ren-li. Analysis of large-span highway tunnel surrounding rock vertical pressure attributes[J]. Journal of Tongji University (Natural Science), 2010, 38(12): 1741-1745. (in Chinese) doi: 10.3969/j.issn.0253-374x.2010.12.005 [23] 曲海锋, 朱合华, 蔡永昌. 扁平大跨度公路隧道松动荷载计算方法探讨[J]. 岩土力学, 2008, 29(4): 989-994, 1000. doi: 10.3969/j.issn.1000-7598.2008.04.025QU Hai-feng, ZHU He-hua, CAI Yong-chang. Discussion on calculation of loose load on extra-large cross-section and large-span road tunnel[J]. Rock and Soil Mechanics, 2008, 29(4): 989-994, 1000. (in Chinese) doi: 10.3969/j.issn.1000-7598.2008.04.025 [24] 段慧玲, 张林. 大跨度公路隧道合理开挖方法对比研究[J]. 土木工程学报, 2009, 42(9): 114-119. https://www.cnki.com.cn/Article/CJFDTOTAL-TMGC200909019.htmDUAN Hui-ling, ZHANG Lin. Comparative study of rational excavation methods for large-span highway tunnels[J]. China Civil Engineering Journal, 2009, 42(9): 114-119. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-TMGC200909019.htm [25] 戴永浩, 陈卫忠, 田洪铭, 等. 大梁隧道软岩大变形及其支护方案研究[J]. 岩石力学与工程学报, 2015, 34(S2): 4149-4156. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX2015S2063.htmDAI Yong-hao, CHEN Wei-zhong, TIAN Hong-ming, et al. Study of large deformation and support measures of Daliang Tunnel with soft surrounding rockmass[J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(S2): 4149-4156. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX2015S2063.htm [26] 陈子全, 何川, 吴迪, 等. 高地应力层状软岩隧道大变形预测分级研究[J]. 西南交通大学学报, 2018, 53(6): 1237-1244. doi: 10.3969/j.issn.0258-2724.2018.06.020CHEN Zi-quan, HE Chuan, WU Di, et al. Study of large deformation classification criterion for layered soft rock tunnels under high geostress[J]. Journal of Southwest Jiaotong University, 2018, 53(6): 1237-1244. (in Chinese) doi: 10.3969/j.issn.0258-2724.2018.06.020 [27] 陈丽俊, 张运良, 马震岳, 等. 软岩隧洞锁脚锚杆-钢拱架联合承载分析[J]. 岩石力学与工程学报, 2015, 34(1): 129-138. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX201501014.htmCHEN Li-jun, ZHANG Yun-liang, MA Zhen-yue, et al. Joint bearing analysis for feet-lock bolt and steel arch in weak rock tunnel[J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(1): 129-138. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX201501014.htm [28] 罗彦斌, 陈建勋. 软弱围岩隧道锁脚锚杆受力特性及其力学计算模型[J]. 岩土工程学报, 2013, 35(8): 1519-1525. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201308021.htmLUO Yan-bin, CHEN Jian-xun. Mechanical characteristics and mechanical calculation model of tunnel feet-lock bolt in weak surrounding rock[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(8): 1519-1525. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201308021.htm [29] CHEN Li-jun, ZHANG Yun-liang, MA Zhen-yue. Analytical approach for support mechanism of feet-lock pipe combined with steel frame in weak rock tunnels[J]. KSCE Journal of Civil Engineering, 2016, 20(7): 2965-2980. doi: 10.1007/s12205-016-0443-3 [30] CHEN Li-jun, CHEN Jian-xun, LUO Yn-bin, et al. Vertical load and settlement at the foot of steel rib with the support of feet-lock pipe in soft ground tunnel[J]. Advances in Civil Engineering, 2019, 2019: 6186748. http://www.researchgate.net/publication/330853288_Vertical_Load_and_Settlement_at_the_Foot_of_Steel_Rib_with_the_Support_of_Feet-Lock_Pipe_in_Soft_Ground_Tunnel [31] HØIEN A H, NILSEN B. Rock mass grouting in the løren tunnel: case study with the main focus on the grout ability and feasibility of drill parameter interpretation[J]. Rock Mechanics and Rock Engineering, 2014, 47(3): 967-983. [32] 王乾, 曲立清, 郭洪雨, 等. 青岛胶州湾海底隧道围岩注浆加固技术[J]. 岩石力学与工程学报, 2011, 30(4): 790-802. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX201104019.htmWANG Qian, QU Li-qing, GUO Hong-yu, et al. Grouting reinforcement technique of Qingdao Jiaozhou Bay Subsea Tunnel[J]. Chinese Journal of Rock Mechanics and Engineering, 2011, 30(4): 790-802. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX201104019.htm