穿越活动逆断层节段式衬砌隧道节段长度优化研究

摘要：為了探求增加穿越活动性断层隧道地下结构刚度和围岩强度的有效方法，以敦格铁路阔克萨隧道为例，利用岩土数值分析软件FLAC3D建立三维数值计算模型，模拟逆断层错动时围岩及支护结构的受力、变形特征，提出了“衬砌节段+剪切缝”的节段式结构设计方案，并对活动性断层隧道节段式衬砌的节段长度进行了优化研究。结果表明：1）节段式衬砌结构在发生位移错动后，最大拉应力主要集中在隧道衬砌墙腰、墙脚处;最大压应力及最大剪应力出现在与断层面相交的节段处;2）在逆断层错动20 cm时，与断层面相交的节段出现竖向位移与刚体旋转相结合的变形特征;3）经过冗余量设计，在敦格铁路活动性断层隧道衬砌断面采用具有预留修复空间的马蹄形扩大断面;4）不同截面厚度的衬砌变形特征基本一致，呈现截面厚度越大，最小主应力与最大剪应力越大的规律，但最大主应力隧截面尺寸变化的规律不明显;5）基于衬砌结构弯矩纵向分布的节段长度要求节段长度需小于最大弯矩间距（18.5 m），结合工程实际，节段式衬砌最优节段长度可设定为18 m。研究结果对于保障隧道施工安全、设计结构稳定具有重要参考价值。

关键词：隧道工程;断层错动;节段式衬砌;冗余量;节段长度;优化设计

中图分类号：U451.4文献标识码：ADOI： 10.7535/hbgykj.2021yx03009

Abstract： In order to explore the effective method to increase the stiffness of underground structure and the strength of surrounding rock of tunnels passing through active faults， taking Kuokesa tunnel of Dunge railway as an example， a three-dimensional numerical model was established by using the geotechnical numerical analysis software FLAC3D to simulate the stress and deformation characteristics of surrounding rock and supporting structure during reverse faults dislocation. The segmental structural design scheme of "lining segment + shear joint" was put forward， and the segment length of segmental lining of active fault tunnel was optimized. The results show that： 1） after the displacement dislocation occurs in the segmental lining structure， the maximum tensile stress is mainly concentrated at the waist and foot of the tunnel lining wall， and the maximum compressive stress and maximum shear stress appear at the segment intersecting with the fault plane; 2） when the reverse fault is staggered for 20 cm， the segment intersecting with the fault plane has the deformation characteristic of the combination of vertical displacement and rigid body rotation;3） after the redundancy design， the horseshoe shaped enlarged section with reserved repair space is adopted in the lining section of Dunge railway active fault tunnel; 4） the deformation characteristics of the lining with different section thicknesses are basically the same， showing the law that the larger the section thickness is， the greater the minimum principal stress and the maximum shear stress are， but the change of the section size of the maximum principal stress tunnel is not obvious; 5） the segment length based on the longitudinal moment distribution of the lining structure requires that the segment length should be less than the maximum moment spacing （18.5 m）. Combined with the engineering practice， the optimal segment length of segmental lining can be set as 18 m. The research results have important reference value for ensuring the safety of tunnel construction and the stability of designing structure.

Keywords：tunnel engineering; fault dislocation; segmental lining; redundancy; segmental length; optimal design

活动性断层广泛分布在全球各地，如美国的圣安德烈斯断层、土耳其的安纳托利亚断层、新西兰的阿尔卑斯断层、德国的莱因地堑以及俄罗斯的贝加尔湖地堑等。……