附加荷载作用下隧道结构力学响应与韧性演化特征

Mechanical Response and Resilence Evolution Characteristics of Tunnel Structures under Additional Loads

外部荷载变化势必诱发隧道结构力学扰动,合理评价隧道结构韧性并保证安全具有重要意义。以典型工程为依托,开展隧道结构受附加荷载影响的力学响应仿真分析,以此为基础构建隧道在附加荷载作用下的韧性评价方法和设防标准,并进行实例隧道韧性演化分析,结合韧性要求提出后期施工外部作用荷载限值。研究结果表明:隧道在单侧附加荷载作用下受荷侧顶板响应最显著,且表现出三边约束单边悬臂承载特性和空间变形效应,在非受荷侧出现轻微翘曲,隧道发生纵向扭转。附加荷载作用下隧道结构最大弯矩增大14.26%,最大裂缝宽度增大27%,最大内力与变形均可控,但结构损伤后韧性会受到影响。隧道结构跨中局部进入塑性状态,附加荷载值与裂缝宽呈线性关系,与冗余度近似为三次函数关系。实例韧性分析说明基于冗余度构建的评价方法具备可行性,结合工程特点和韧性要求提出的附加荷载限值可为现场实施提供科学依据。

Changes in external loads inevitably induce mechanical disturbances in tunnel structures,making it crucial to evaluate their resilence reasonably and ensure safety.This study,based on a typical project,conducts a simulation analysis of the mechanical response of tunnel structures under additional loads.A resilence evaluation method and fortification standards for tunnels subjected to additional loads are developed.The analysis includes the resilence evolution of a specific tunnel and proposes limits for external loading during subsequent construction based on resilence requirements.The research results indicate that the response of the tunnel crown is most significant under unilateral additional loading,exhibiting characteristics of a cantilever with three-sided constraints and spatial deformation effects.A slight warping occurs on the unloaded side,leading to longitudinal twisting of the tunnel.Under additional loads,the maximum bending moment in the tunnel structure increases by 14.26%,and the maximum crack width increases by 27%.Both the maximum internal force and deformation are controllable;however,resilence is affected after structural damage.The midpoint of the tunnel structure enters a plastic state,and there is a linear relationship between the additional load and crack width,which approximates a cubic function relationship with redundancy.The resilence analysis of the case study demonstrates the feasibility of the evaluation method based on redundancy and proposes additional load limits in line with engineering characteristics and resilence requirements,providing a scientific basis for on-site implementation.