大断面古土壤隧道围岩压力分布规律及支护结构受力特征分析——以银西高铁早胜3号隧道为例
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摘要
银西高铁早胜3号隧道位于甘肃省宁县境内,为国内首条穿越古土壤地层的隧道。为研究隧道穿越古土壤地层时围岩压力分布情况及支护结构受力变形特征,通过在隧道相同里程布设压力盒、表面应变计和钢筋应力计等传感器,对围岩压力、初期支护受力变形情况进行长期现场监测,并将监测结果得到的频率值换算为力值或应变,最后对数据进行分析。结果表明:1)对于三台阶七步开挖法,围岩压力大致经历了急剧变化—缓慢变化—平稳变化3个阶段,三台阶七步开挖的施工工法决定了相同里程先开挖一侧围岩压力明显大于后开挖一侧; 2)钢拱架呈现三维受力状态,相邻2榀拱架间轴力以受压为主,支护结构的完整程度以及与混凝土的协作关系直接影响轴力变化情况; 3)拱脚应变的最大值主要集中在上台阶和仰拱底部附近。
Zaosheng No.3 Tunnel on Yinchuan-Xi′an High-speed Railway, the first tunnel crossing paleosol stratum in China, is located in Ningxian County, Gansu Province. In order to study the pressure distribution of surrounding rock and the stress and deformation characteristics of supporting structure when tunnel crossing paleosol stratum, the pressure box, surface strain gauge and steel bar stress gauge are installed at a same mileage of tunnel to monitor the pressure of surrounding rock and the stress and deformation of primary support for a long time. And then the frequency obtained is converted to force or strain, and finally the data are analyzed. The results show that:(1) For the three-bench seven-step excavation method, the pressure of the surrounding rock has experienced three stages, i.e. rapid change, slow change and steady change; by using the three-bench seven-step excavation method, the pressure of the surrounding rock excavated firstly is obviously larger than that at the side excavated lately at a same mileage.(2) The steel arch presents a three-dimensional stress state, the axis force of the two adjacent arches is mainly subjected to pressure, and the degree of integration of the supporting structure and the cooperation with the concrete directly affect the axial force.(3) The maximum strain of the arch feet is mainly concentrated on the bottom of the top heading and the bottom of the inverted arch.
Zaosheng No.3 Tunnel on Yinchuan-Xi′an High-speed Railway, the first tunnel crossing paleosol stratum in China, is located in Ningxian County, Gansu Province. In order to study the pressure distribution of surrounding rock and the stress and deformation characteristics of supporting structure when tunnel crossing paleosol stratum, the pressure box, surface strain gauge and steel bar stress gauge are installed at a same mileage of tunnel to monitor the pressure of surrounding rock and the stress and deformation of primary support for a long time. And then the frequency obtained is converted to force or strain, and finally the data are analyzed. The results show that:(1) For the three-bench seven-step excavation method, the pressure of the surrounding rock has experienced three stages, i.e. rapid change, slow change and steady change; by using the three-bench seven-step excavation method, the pressure of the surrounding rock excavated firstly is obviously larger than that at the side excavated lately at a same mileage.(2) The steel arch presents a three-dimensional stress state, the axis force of the two adjacent arches is mainly subjected to pressure, and the degree of integration of the supporting structure and the cooperation with the concrete directly affect the axial force.(3) The maximum strain of the arch feet is mainly concentrated on the bottom of the top heading and the bottom of the inverted arch.
引文
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[10] 孟德鑫, 谭忠盛. 大断面黄土隧道变形控制技术及支护受力特征[J]. 土木工程学报, 2015, 48(增刊1): 383.MENG Dexin, TAN Zhongsheng. Deformation control technology and supporting structure stress of large section loess tunnel [J].China Civil Engineering Journal, 2015, 48(S1): 383.
[11] 李鹏飞, 赵勇, 张顶立, 等. 基于现场实测数据统计的隧道围岩压力分布规律研究[J]. 岩石力学与工程学报, 2013, 32(7): 1392.LI Pengfei, ZHAO Yong, ZHANG Dingli, et al. Study of distribution laws of tunnel surrounding rock pressure based on field measured data statistics [J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32(7): 1392.
[12] 陈峰宾. 隧道初期支护与软弱围岩作用机理及应用[D]. 北京: 北京交通大学, 2012.CHEN Fengbin. Application and mechanism of primary support and surrounding rock in weak rock tunnel [D]. Beijing: Beijing Jiaotong University, 2012.
[13] 郑选荣. 西安地铁暗挖黄土隧道围岩变形特性及控制技术研究[D]. 西安: 西安科技大学, 2015.ZHENG Xuanrong. Study of deformation characteristics and control measures of shallow-buried excavation in loess tunnel of Xi′an Subway [D]. Xi′an: Xi′an University of Science and Technology, 2015.
[14] 靳金. 大断面黄土隧道开挖变形监测研究及施工过程分析[D]. 兰州: 兰州交通大学, 2017.JIN Jin. Research on large cross-section loess tunnel excavation deformation monitoring and analysis of construction process [D]. Lanzhou: Lanzhou Jiaotong University, 2017.
[15] 曹春山, 吴树仁, 潘懋, 等. 古土壤力学特性及其对黄土滑坡的意义[J]. 水文地质工程地质, 2016, 43(5): 127.CAO Chunshan, WU Shuren, PAN Mao, et al. Mechanics characteristics of paleosol and its implication to loess landslide [J]. Hydrogeology and Engineering Geology, 2016, 43(5): 127.
[2] 杨萍, 叶玮. 古土壤记录的内蒙古沙区全新世环境变化[J]. 中国沙漠, 2013, 33(6): 1670.YANG Ping, YE Wei. Environment changes of sand fields in Inner Mongolia, China since the holocene recorded by sandy paleosol [J]. Journal of Desert Research, 2013, 33(6): 1670.
[3] 陈留勤, 刘鑫, 李鹏程. 古土壤: 沉积环境和古气候变化的灵敏指针[J]. 沉积学报, 2018, 36(3): 511.CHEN Liuqin, LIU Xin, LI Pengcheng. Paleosols: Sensitive indicators of depositional environments and paleocli-mate [J]. Acta Sedimentologica Sinica, 2018, 36(3): 511.
[4] 赵景波, 罗小庆, 刘瑞, 等. 关中平原黄土中第1层古土壤发育时的土壤水分研究[J]. 地质学报, 2015, 89(12): 2389.ZHAO Jingbo, LUO Xiaoqing, LIU Rui, et al. Research in soil moisture during development of S1 paleosol in Guanzhou plain [J]. Acta Geoglgica Sinica, 2015, 89(12): 2389.
[5] 刘东生.黄土与环境[M]. 北京: 科学出版社, 1985.LIU Dongsheng. Loess and environment[M]. Beijing: Science Press, 1985.
[6] 郭正堂, 刘东生, 安芷生. 渭南黄土沉积中十五万年来的古土壤及其形成时的古环境[J]. 第四纪研究, 1994, 8(3): 256.GUO Zhengtang, LIU Dongsheng, AN Zhisheng. Paleosols of last 0.15 Million year in Weinan loess section and their paleoclimatic significance [J].Quaternary Sciences, 1994, 8(3): 256.
[7] 吴克宁, 王文静, 查理思, 等. 文化遗址区古土壤特性及古环境研究进展[J].土壤学报, 2014, 51(6): 1169.WU Kening, WANG Wenjing, ZHA Lisi, et al. Review of paleosol and palaeoenvironment in ancient culture sites [J]. Acta Pedologica Sinica, 2014, 51(6): 1169.
[8] 扈世民.大断面黄土隧道围岩变形特征及控制技术研究[D]. 北京: 北京交通大学, 2012.HU Shimin. Research on deformation characteristics and control measures of large cross-section loess tunnel [D]. Beijing: Beijing Jiaotong University, 2012.
[9] 周云鹏. 超大断面黄土公路隧道衬砌受力变形特性研究[D]. 西安: 西安科技大学, 2014.ZHOU Yunpeng. Study of mechanical characteristics of lining for super-large cross-section loess highway tunnel [D]. Xi′an: Xi′an University of Science and Technology, 2014.
[10] 孟德鑫, 谭忠盛. 大断面黄土隧道变形控制技术及支护受力特征[J]. 土木工程学报, 2015, 48(增刊1): 383.MENG Dexin, TAN Zhongsheng. Deformation control technology and supporting structure stress of large section loess tunnel [J].China Civil Engineering Journal, 2015, 48(S1): 383.
[11] 李鹏飞, 赵勇, 张顶立, 等. 基于现场实测数据统计的隧道围岩压力分布规律研究[J]. 岩石力学与工程学报, 2013, 32(7): 1392.LI Pengfei, ZHAO Yong, ZHANG Dingli, et al. Study of distribution laws of tunnel surrounding rock pressure based on field measured data statistics [J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32(7): 1392.
[12] 陈峰宾. 隧道初期支护与软弱围岩作用机理及应用[D]. 北京: 北京交通大学, 2012.CHEN Fengbin. Application and mechanism of primary support and surrounding rock in weak rock tunnel [D]. Beijing: Beijing Jiaotong University, 2012.
[13] 郑选荣. 西安地铁暗挖黄土隧道围岩变形特性及控制技术研究[D]. 西安: 西安科技大学, 2015.ZHENG Xuanrong. Study of deformation characteristics and control measures of shallow-buried excavation in loess tunnel of Xi′an Subway [D]. Xi′an: Xi′an University of Science and Technology, 2015.
[14] 靳金. 大断面黄土隧道开挖变形监测研究及施工过程分析[D]. 兰州: 兰州交通大学, 2017.JIN Jin. Research on large cross-section loess tunnel excavation deformation monitoring and analysis of construction process [D]. Lanzhou: Lanzhou Jiaotong University, 2017.
[15] 曹春山, 吴树仁, 潘懋, 等. 古土壤力学特性及其对黄土滑坡的意义[J]. 水文地质工程地质, 2016, 43(5): 127.CAO Chunshan, WU Shuren, PAN Mao, et al. Mechanics characteristics of paleosol and its implication to loess landslide [J]. Hydrogeology and Engineering Geology, 2016, 43(5): 127.