Theoretical Analysis of Bearing Mechanism of Pipe Sheds
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摘要:
建立合理准确的管棚理论分析模型并对其进行求解,对推动管棚预支护技术的进一步发展具有重要意义. 本文在隧道开挖、支护的施工过程以及未开挖段由于掌子面扰动而导致管棚约束反力有所降低的基础上,建立了基于Euler-Bernoulli梁理论的管棚荷载结构模型,同时引入Pasternak弹性地基模型来确定初期支护及掌子面前方岩体对管棚的约束反力,推导出每一循环隧道开挖支护过程中管棚的受力和变形解析表达式,并通过叠加法求解掌子面掘进至任意位置时管棚的受力和变形分布;通过案例比对,验证了本文建立模型的合理性和有效性. 研究结果表明:管棚钢管环向间距越小、直径越大越有利于提升管棚的预加固能力;管棚合理搭接长度为1.8 m.
Abstract:Establishing a reasonable and accurate theoretical analysis model for pipe sheds and solving it are of great significance to promoting the development of pipe shed pre-support technology. By analyzing the construction process of tunnel excavation and support and the reduction of the restraining reaction force of the pipe shed due to the disturbance of the tunnel face in the unexcavated section, a load structure model of the pipe shed based on the Euler-Bernoulli beam theory was established. The Pasternak elastic foundation model was introduced to determine the initial support and the restraining reaction force of the rock mass in front of the tunnel face on the pipe shed, and the analytical expressions of the stress and deformation of the pipe shed during each cycle of tunnel excavation and support were derived. In addition, the superposition method was used to solve the stress and deformation distribution of the pipe shed when the tunnel face was tunneled to any position. Through case comparison, the rationality and effectiveness of the model were verified. The research results show that smaller circumferential spacing and larger diameter of the pipe shed steel pipes are helpful in improving the pre-reinforcement capacity of the pipe shed, and the reasonable lap length of the pipe shed is 1.8 m.
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Key words:
- tunnel engineering /
- pipe shed /
- design parameter /
- analytical solution
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表 1 Pasternak弹性地基参数
Table 1. Pasternak elastic foundation parameters
项目 基床系数/(kN·m−3) 地基剪切模量/(kN·m−1) 初期支护 7.84 × 107 9.51 × 104 岩体 1.64 × 105 1.63 × 103 -
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