中老铁路膨胀性盐岩地层隧道结构体系优化及施工技术探究  

Structural System Optimization and Construction Technology of Tunnel in Expansive Salt Rock Stratum for China-Laos Railway

作　　者：王志杰[1] 李金宜 周飞聪 姜逸帆 周平[1] 邓宇航 林嘉勇 WANG Zhijie;LI Jinyi;ZHOU Feicong;JIANG Yifan;ZHOU Ping;DENG Yuhang;LIN Jiayong(Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu 610031,Sichuan,China)

机构地区：[1]西南交通大学交通隧道工程教育部重点实验室,四川成都610031

出　　处：《隧道建设（中英文）》2021年第1期16-27,共12页Tunnel Construction

基　　金：国家自然科学基金(51678498);中央高校基本科研业务专项资金(SWJTU11ZT33);教育部创新团队发展计划(IRT0955);国家自然科学基金委员会高铁联合基金项目(U1934213)。

摘　　要：为解决膨胀性盐岩地层隧道修建时出现的大量衬砌裂缝、仰拱底鼓开裂等问题,同时为保证隧道后续快速安全施工及长期健康服役,采用现场调查、数值模拟和监控量测等方法,对膨胀性盐岩地层隧道结构及施工技术进行深入研究。研究结果表明:1)含盐地下水对混凝土的侵蚀引起的膨胀压力是原马蹄形隧道衬砌开裂的根本原因。2)250 kPa的地层膨胀压力可大幅度增大围岩变形,但对隧道掌子面纵向挤压变形基本没有影响,可减小拱顶处的最大主应力,但会大幅度增大仰拱处最小主应力。3)多层支护可对洞周围岩变形起到积极的约束作用,也可明显减小掌子面纵向变形,对初期支护最大主应力基本无影响;无膨胀压力时,会引起墙脚最小主应力集中;有膨胀压力时,可减小其他部位的最小主应力。综合考虑围岩稳定性、支护受力以及施工成本控制等,膨胀性盐岩地层多层支护隧道施工宜采用二台阶法。现场实测证明采用3层衬砌、2层防水、全环注浆并施作隧底阻水榫后,围岩变形量小,衬砌未开裂。通过指数函数对围岩变形进行拟合,证明数值计算结果基本可靠。When constructing a tunnel in expansive salt rock strata,problems such as extensive lining cracking and inverted arch cracking will be encountered.To ensure rapid construction and long-term effective service of such a tunnel,the field investigation,numerical simulation,and field measurement of the tunnel structure and construction technology in an expansive salt rock stratum are analyzed.The following results are obtained.(1)The expansion pressure caused by erosion of the concrete by saline groundwater is the root cause of the original lining cracking in the horseshoe-shaped tunnel.(2)An expansion pressure of 250 kPa significantly increases the deformation of the surrounding rock but has a negligible effect on the longitudinal deformation of the tunnel face.This reduces the maximum principal stress at the crown but significantly increases the minimum principal stress at the inverted arch.(3)Multilayer supports can play a positive role in restraining the deformation of the surrounding rock and can significantly reduce the longitudinal deformation of the tunnel face.However,it has no effect on the maximum principal stress of the primary support.The absence of expansion pressure causes the minimum principal stress to concentrate at the wall foot,whereas the presence of this pressure reduces the minimum principal stress in other parts.Considering the stability of the surrounding rock,supporting force,and construction cost,a two-bench method is recommended for installing multi-layer supports in tunnels constructed in expansive salt rock strata.The field measurement shows that the deformation degree of the surrounding rock is small and that the lining is not cracked after installing three layers of concrete,two layers of waterproof material,full-ring grout,and water blocking tenons in the bottom of the tunnel.Fitting the deformation of the surrounding rock with the exponential function proves the accuracy of the numerical calculation.

关 键 词：盐岩地层隧道 膨胀压力 结构优化 数值模拟 现场监测 

分 类 号：U455.4[建筑科学—桥梁与隧道工程]