八达岭长城站超大断面过渡段暗挖施工新技术
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摘要
京张高速铁路八达岭长城站为地下暗挖车站,过渡段设计为单跨形式,最大开挖跨度32.7 m,最大开挖面积497 m2。为了解决超大断面隧道开挖过程中围岩变形大、容易失稳,多导坑法开挖无法采用大型机械施工、进度慢,隧道内预应力锚索施工难度大等难题,文章采用顶洞超前、分层下挖、核心预留、重点锁定的开挖工法(简称"DFHZ工法"),并对该工法的优点和施工流程进行了介绍,该工法既能保证隧道开挖过程中的安全、减少围岩的沉降和变形,又方便机械化施工。采用预应力锚杆和预应力锚索结合使用,以发挥围岩的自承载能力,保证围岩稳定,预应力锚索施工中采用增设锚固结、硫铝酸盐水泥配置浆液、先自由段后锚固段的注浆顺序、高压注浆等措施,可以大大加快锚索施工进度,保证锚索质量。通过对张家口端进行监控量测,发现拱顶下沉和水平收敛值都很小,说明采用的支护措施可行,并对北京段过渡段进行了优化设计。
The Badaling Great Wall Station on Beijing-Zhangjiakou High-speed Railway is an underground mined station,of which the transition section is designed as a single span with a maximum excavation span of 32.7 m and a maximum excavation area of 497 m~2. The surrounding rock of super-large cross-section tunnel is always characterized by large deformation and instability, the large-scale mechanical construction cannot be applied to multi-guide pilot excavation,the construction speed is low,and the prestressed anchorage cable in tunnel is difficult to be carried out.Hence,the so called DFHZ method,advanced excavation of tunnel top,layered downward excavation,core soil reserved and keys locking,is adopted,and the advantages of construction flowchart of the method are introduced. By adopting the above-mentioned method,the tunnel safety can be guaranteed,the deformation and settlement of the surrounding rock can be reduced,and the mechanical construction is available. The stability of the surrounding rock can be guaranteed by using prestressed anchor rod and prestressed anchorage cable. During the construction of prestressed anchorage cable,the technologies,i. e. adding anchoring joints,setting up slurry with sulphoaluminate cement,free section grouting and then anchoring section,and high-pressure grouting,etc.,are adopted to shorten the construction schedule of anchorage cable and guarantee its safety. The monitoring results of crown top settlement and horizontal convergence at Zhangjiakou End are small,which indicates the rationality of the above-mentioned method.
The Badaling Great Wall Station on Beijing-Zhangjiakou High-speed Railway is an underground mined station,of which the transition section is designed as a single span with a maximum excavation span of 32.7 m and a maximum excavation area of 497 m~2. The surrounding rock of super-large cross-section tunnel is always characterized by large deformation and instability, the large-scale mechanical construction cannot be applied to multi-guide pilot excavation,the construction speed is low,and the prestressed anchorage cable in tunnel is difficult to be carried out.Hence,the so called DFHZ method,advanced excavation of tunnel top,layered downward excavation,core soil reserved and keys locking,is adopted,and the advantages of construction flowchart of the method are introduced. By adopting the above-mentioned method,the tunnel safety can be guaranteed,the deformation and settlement of the surrounding rock can be reduced,and the mechanical construction is available. The stability of the surrounding rock can be guaranteed by using prestressed anchor rod and prestressed anchorage cable. During the construction of prestressed anchorage cable,the technologies,i. e. adding anchoring joints,setting up slurry with sulphoaluminate cement,free section grouting and then anchoring section,and high-pressure grouting,etc.,are adopted to shorten the construction schedule of anchorage cable and guarantee its safety. The monitoring results of crown top settlement and horizontal convergence at Zhangjiakou End are small,which indicates the rationality of the above-mentioned method.
引文
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[2]冀东升.超大断面隧道开挖施工技术[J].交通世界,2018(24):106.JI Dongsheng. Excavation construction technology of superlarge section tunnel[J]. Transport World,2018(24):106.
[3]吴金建.全强风化花岗岩大断面隧道施工技术研究[J].铁道勘察,2018,44(4):100.WU Jinjian. Study on construction technology for fullyweathered granite large section tunnel[J]. RailwayInvestigation and Surveying,2018,44(4):100.
[4]孙智,王春河,油新华,等.复杂条件超大断面隧道围岩控制技术研究[J].施工技术,2018,47(19):9.SUN Zhi,WANG Chunhe,YOU Xinhua,et al. Study onsurrounding rock control technology of super large crosssection tunnel under complex conditions[J]. ConstructionTechnology,2018,47(19):9.
[5]官嘉.超大断面隧道变截面段的施工研究[J].佳木斯职业学院学报,2018(3):495.GUAN Jia. Study on construction of variable section of super-large section tunnel[J]. Journal of Jiamusi VocationalInstitute,2018(3):495.
[6]皇民,肖昭然,郭成龙,等.双侧壁导坑与CD法对超大断面隧道开挖影响分析[J].交通科技与经济,2016,18(4):63.HUANG Min, XIAO Zhaoran, GUO Chenglong, et al.Impact analysis of double side-wall pilot tunnel method andCD method of large cross section tunnel excavation[J].Technology&Economy in Areas of Communications,2016,18(4):63.
[7]宋涛.市政工程超大断面隧道双侧壁导坑法施工的改进探索[J].价值工程,2018,37(17):137.SONG Tao. Improvement on construction of double-sidewallpit for super large section tunnel in municipal engineering[J]. Value Engineering,2018,37(17):137.
[8]仇在林.超大断面隧道小导洞先行与台阶反扩挖施工技术研究[J].公路工程,2018,43(4):48.QIU Zailin. Research on the construction technology of smallguide hole and step reverse expansion for large cross sectiontunnel[J]. Highway Engineering,2018,43(4):48.
[9]王哲宇,阳生权,黄飞.超大断面轻轨车站中洞法隧道施工技术研究[J].湖南工程学院学报(自然科学版),2016,26(1):90.WANG Zheyu, YANG Shenquan, HUANG Fei. Tunnelconstruction technology and engineering practice by centerdrift method in light rail station[J]. Journal of HunanInstitute of Engineering(Natural Science Edition),2016,26(1):90.
[10]卿伟宸,高杨,朱勇,等.特大跨度四线深埋隧道施工工法研究:以乌蒙山2号出口车站隧道为例[J].隧道建设,2018,38(1):91.QING Weichen, GAO Yang, ZHU Yong, et al.Construction methods for ultra large-span four-track deeptunnel on Wumengshan No. 2 exit section[J]. TunnelConstruction,2018,38(1):91.
[11]陈明.铁路隧道软弱围岩段分修变合修大跨过渡段施工技术[J].建筑工程技术与设计(路桥工程),2014,(12):99.CHEN Ming. Construction technology of long span transitionsection of railway tunnel in soft surrounding rock[J].Construction Engineering Technology and Design(Roadand Bridge Engineering),2014(12):99.
[12]王定宝,冯赟.凤凰山隧道分合修大跨段复合双侧壁导坑法施工[J].中外公路,2015,36(5):92.WANG Dingbao, FENG Yun. Construction of combineddouble side wall pit in long span section of Fenghuangshantunnel[J]. Chinese and Foreign Highways,2015,36(5):92.
[13]闫明超,曾鹏,何知思,等.超大断面隧道变截面段施工技术研究[J].铁道建筑,2015(7):43.YAN Mingchao,ZENG Peng,HE Zhisi,et al. Study ofconstruction technology of super-large area and variable cross-section tunnel[J]. Railway Engineering,2015(7):43.
[14]张群健.新考塘隧道超大断面施工技术[J].贵州大学学报(自然科学版),2015(2):124.ZHANG Qunjian. Xinkaotang Tunnel super-large crosssection construction technology[J]. Journal of GuizhouUniversity(Natural Science),2015(2):124.
[15]洪军,郭海满,张俊儒,等.新考塘隧道出口三线渐变段结构选型与施工工法研究[J].隧道建设,2016,36(8):953.HONG Jun,GUO Haiman,ZHANG Junru,et al. Study onstructural selection and construction method for three-linetransition section at exit of Xinkaotang Tunnel[J]. TunnelConstruction,2016,36(8):953.