地裂缝环境下盾构隧道结构性状及适应性研究

为了揭示地裂缝环境下不同拼装方式盾构地铁隧道结构性状及适应性,以拟建西安地铁8号线为依托工程,考虑采用盾构隧道穿越地裂缝场地为工程背景,建立三维有限元数值模型,对地裂缝错动作用下不同拼装方式盾构隧道结构变形与内力及适应性进行分析。主要结论:地裂缝错动时通缝拼装盾构隧道沉降变形明显大于错缝拼装盾构隧道;拼装方式对管片衬砌结构内力分布规律的影响不大,均表现为拱底位置出现管片接头挤压破坏和两侧拱腰位置受剪最为严重,但数值上通缝隧道内力更小一些;通缝隧道的环间相对垂直位错量及影响范围均大于错缝隧道。从地裂缝场地盾构隧道适应性来看,当地裂缝位错量s≤10 cm时,两种拼装方式的盾构隧道均可用于地裂缝场地,而当地裂缝位错量s>10 cm时,错缝拼装的盾构隧道更适合地裂缝场地。

Study on Structural Behaviors and Adaptability of Shield Tunnel in the Ground Fissure Environment

In order to reveal the structural behaviors and adaptability of metro shield tunnels of different assembling types passing through active ground fissure site, a three-dimensional finite element model is established to study the deformation characteristics and segmental forces response of shield tunnels of different assembling types and their adaptability in ground fissure area with reference to the proposed Xi’an metro line 8 through ground fissures. The results show that under the same dislocation of active ground fissure, the settlement deformation of straight-joint assembling shield tunnel is obviously larger than that of staggered-joint assembling shield tunnel, the distribution regulations of lining internal force for the two assembling types are basically the same, the extrusion failure of segmental joints is likely to occur at the arch bottom, and the internal force of the segmental lining in straight-joint assembling shield tunnel is smaller than that in staggered-joint assembling shield tunnel. The straight-joint and staggered-joint assembling shield tunnels are most severely sheared at the arch waist on both sides. The influence range and relative vertical dislocation values between rings of the straight-joint assembling shield tunnel is larger than that of the staggered-joint assembling shield tunnel. The adaptability analysis of shield tunnels passing through ground fissure site shows that when the dislocation of ground fissure is smaller than 10 cm, both straight-joint and staggered-joint assembling shield tunnels are adaptable, and when the dislocation is greater than 10 cm, the staggered-joint assembling shield tunnel is more suitable.