摘要
为了选取合适的穿越活动断裂带铁路隧道安全防控措施,以东非大裂谷东翼地区恩贡隧道为例,采用现场地质调查及理论分析方法,对隧道穿越的断裂带范围内地层结构进行针对性研究,对其地质特征及断裂活动进行总结评价,进而推断出对隧道工程的影响,制定隧道专项设计原则及方案。研究表明,该隧道工程区域内的活动断裂以正断层陡坎形式分布,当7级强震发生时,隧道穿越的断裂带会发生0.9 m平均垂直位移,针对这些裂谷区域可预见的地质灾害,应在设计初期阶段进行规避或预防。研究结果表明,(1)线路应尽可能地规避地质不利地层,若无法绕避,则应采用易于修复的隧道、路基等结构大角度通过;(2)考虑震后的可修复性,应在线路平纵曲线要素的设计上留有足够的富余量,以满足震后调坡需求;(3)应在建设初期对隧道二衬结构内轮廓进行包容性设计,使其灾后隧道内轮廓仍满足列车正常通行的限界要求;(4)针对震后修复需求,对隧道内部轨下结构形式、接触网悬挂方式、水沟电缆槽形式及隧道分节段的结构形式进行特殊设计,使隧道在震后拥有快速恢复正常使用的能力。
In order to select appropriate safety measures for the railway tunnel crossing the active fault zone,taking the Ngong tunnel in the eastern wing of the East African Rift Valley as an example,a combination of field geological investigation and theoretical analysis methods were employed to conduct targeted research on the geological structure within the fault zone through which the tunnel passes.The geological characteristics and fault activity were summarized and evaluated,and the impact on the tunnel project was inferred,leading to the formulation of specialized design principles and plans for the tunnel.The study reveals that the active faults in the tunnel project area are distributed in the form of steeply inclined normal faults.When a magnitude 7 earthquake occurs,the fault zone crossed by the tunnel will experience an average vertical displacement of 0.9 meters.In response to these foreseeable geological hazards in the rift valley areas,avoidance or prevention measures should be implemented during the initial design phase.The research results suggest the following:(1)The route should avoid geologically unfavorable strata as much as possible.If avoidance is not feasible,structures such as tunnels and embankments with large angles should be used for easy repair.(2)Considering post-earthquake reparability,sufficient redundancy should be included in the design of longitudinal curve elements to meet the requirements for slope adjustment after an earthquake.(3)In the initial construction phase,the outline of the secondary lining structure of the tunnel should be designed to be inclusive,ensuring that the post-disaster tunnel interior meets the clearance requirements for normal train passage.(4)To meet the post-earthquake repair needs,special designs should be made for the track substructure within the tunnel,the suspension method of the overhead contact system,the form of water drainage cable troughs,and the segmental structure of the tunnel,so that the tunnel has the ability to quickly recover and resume normal use after an earthquake.
作者
孙瑞杰
杨慧林
陈平
甘川
胡楠
吴群辉
SUN Ruijie;YANG Huiin;CHEN Ping;GANG Chuan;HU Nan;WU Qunhui(CCCC Rail Transit Technology Research and Development Center,Beijing 10088,China;China Road&Bridge Corporation,Beijing 100011,China;Faculty of Architecture,Civil and Transportation Engineering,Beijing University of Technology,Beijing 100124,China)
出处
《铁道勘察》
2024年第2期125-132,共8页
Railway Investigation and Surveying
基金
中国交通建设集团有限公司重大基础研究发展项目(2017-ZJKJ-08)
国家科技重大专项(2016ZX05034-003)。
关键词
内马铁路
东非大裂谷
断裂带
恩贡隧道
设计方案
地质特征
Nariobi-Malaba Railway
The Great Rift Valley
active fracture zone
Ngong tunnel
design scheme
geological characteristics
