某不等跨分岔隧道力学特性与三维空间压力拱分析  

Mechanical characteristics and three-dimensional pressure arch of a branch-out tunnel with unequal-span

作　　者：安永林[1] 李佳豪 周进 谭格宇 刘文娟 AN Yonglin;LI Jiahao;ZHOU Jin;TAN Geyu;LIU Wenjuan(School of Civil Engineering,Hunan University of Science and Technology,Xiangtan 411201,China;School of Material Science and Engineering,Hunan University of Science and Technology,Xiangtan 411201,China)

机构地区：[1]湖南科技大学土木工程学院,湖南湘潭411201 [2]湖南科技大学材料科学与工程学院,湖南湘潭411201

出　　处：《铁道科学与工程学报》2022年第12期3705-3714,共10页Journal of Railway Science and Engineering

基　　金：湖南省自然科学基金资助项目(2021JJ30248,2019JJ50191);湖南省教育厅资助项目(20A1873)。

摘　　要：为揭示不等跨分岔隧道反向施工变形受力特性,建立三维仿真模型,分析不同开挖步下,不等跨分岔隧道的竖向位移、水平位移与纵向位移特性,并分析其应力特性,进而分析中夹岩的变形受力特征,并首次从三维压力拱角度,分析不等跨隧道反向施工下压力拱三维特性;最后根据现场监测与施工情况,分析其效果。研究结果表明:围岩竖向位移呈现树杈型;开挖匝道与大跨段右半导坑时,竖向位移较小,当反向开挖左半导坑时,大跨段拱顶上方竖向位移急剧变大;塑性应变较大值与应力集中位置对应,即位于隧道拱脚、小净距与大跨段相接的过渡段(即端头墙)、中夹岩柱靠近匝道段一侧;中夹岩由于受到匝道与主车道隧道不等跨反向开挖的影响,呈现明显的不对称受力与变形,应对其采取不对称支护。由于掌子面的空间效应,隧道开挖至特征面前4 m处时,特征面开始出现压力拱;向特征面后开挖4~8 m处时,对应力拱影响最大;继续开挖后,影响逐渐变小;压力拱三维形状呈现由半喇叭型向圆三角型转变。In order to reveal the deformation and stress characteristics of reverse construction of branch-out tunnels with unequal-span, a three-dimensional simulation model was established. The characteristics of vertical displacement, horizontal displacement and longitudinal displacement of unequal-span tunnels under different excavation steps were analyzed, as well as the stress characteristics. Furthermore, the deformation and stress characteristics of the sandwiched rock were analyzed, and the three-dimensional characteristics of the pressure arch under the reverse construction of the unequal-span tunnel were analyzed from the perspective of the threedimensional pressure arch. Finally, according to the on-site monitoring and construction situation, the effect was analyzed. The result shows: The vertical displacement of surrounding rock presents a tree branch type. When excavating the ramp and the right drift heading of the large-span section, the vertical displacement is small. When excavating the left drift heading in reverse, the vertical displacement above the vault of the large-span section increases sharply. The larger value of plastic strain corresponds to the location of stress concentration, that is, it is located at the tunnel arch foot, the transition section where the small clear distance section and the large span section are connected(namely, the end wall), and the side of the middle rocky column near the ramp section. The sandwiched rock due to the impact of unequal span reverse excavation of the ramp and the main lane tunnel,showed asymmetrical force and deformation obviously, asymmetric support should be adopted. Due to the spatial effect of the tunnel face, when the tunnel is excavated to 4m in front of the characteristic surface, the pressure arch begins to appear on the characteristic surface;and when the tunnel is excavated 4-8m behind the characteristic surface, it has the greatest impact on the stress arch. With the continuous excavation of the tunnel,the impact becomes smaller gradually. The thr

关 键 词：不等跨隧道 分岔隧道 力学特性 中夹岩 压力拱 

分 类 号：U459.2[建筑科学—桥梁与隧道工程]