超前管棚承载机理及力学特性分析和工程应用探讨

Analysis of the Load Bearing Mechanism and Mechanical Properties of the Advanced Pipe Roof and Discussion on Its Engineering Application

  • 摘要: 为探明管棚承载变形特性,优化支护方案,确保不良地质隧道施工安全,结合管棚结构及施工特点,从支护机理、环境影响机理及空间约束效应方面阐述超前管棚的作用原理,揭示其分段式承载特点。基于Pasternak弹性地基梁理论建立管棚施工全过程力学分析模型,依托福建某大跨度隧道工程对管棚力学特性及参数影响进行分析。研究结果表明,通过注浆提升岩土体地基反力系数可使管棚变形降低,增加开挖进尺会使管棚变形非线性增大;管棚管径、壁厚、间距也是影响管棚变形的重要因素,各参数对管棚变形的影响程度从小到大依次为开挖进尺、地基反力系数、管棚直径、间距和壁厚;管棚优化设计应充分考虑不同参数的匹配性及其对变形控制的联动作用和环境影响效应。

     

    Abstract: To understand the load bearing and deformation characteristics of the pipe roof and optimize the support scheme, ensuring the safe construction of tunnels in poor geological conditions, this paper discusses the role of advanced pipe roof in terms of support mechanisms, environmental influence, and spatial constraint effects. The segmented load bearing characteristics of the pipe roof are revealed. Based on the Pasternak elastic foundation beam theory, a mechanical analysis model for the entire construction process of the pipe roof is established. An analysis of the mechanical characteristics and parameter influences of the pipe roof is conducted using a large-span tunnel project in Fujian as a case study. The results show that grouting to improve the foundation reaction coefficient of rock and soil mass can reduce the deformation of the pipe roof. Increasing excavation round length will cause the pipe roof deformation to increase non-linearly. The pipe roof's diameter, wall thickness, and spacing are significant factors affecting its deformation. The influence of each parameter on pipe roof deformation, from smallest to largest,is as follows: excavation round length, foundation reaction coefficient, pipe roof diameter, spacing, and wall thickness. The optimized design of the pipe roof should consider the compatibility of different parameters, their couplling effects on deformation control, and environmental impact effects.

     

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