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高地应力软岩大变形隧道施工极易发生围岩坍塌、结构失稳现象,钢支撑能够有效提高支护结构安全度。以贵广铁路胡山隧道为背景,建立三维有限元数值模型,研究施工过程中钢支撑弯矩、轴力,以及安全系数。研究表明:V级围岩隧道拱顶所承受的弯矩大小约为23.3 6kN·m,I14钢支撑刚好满足抗弯要求。VI级围岩隧道拱顶所承受的弯矩大小约为56.6kN·m,采用I18钢支撑或者双层I14型钢支撑才能保证隧道围岩稳定性。研究成果将为对今后高地应力软岩大变形隧道钢支撑安全设计和施工提供理论依据和参考。
High stress in large soft rock deformation tunnel construction prone to rock collapse, structural instability, steel support can effectively improve the safety of the support structure. Based on Hu Shan Tunnel of Gui-Guang Railway, a three-dimensional finite element numerical model is established to study the steel support moment, axial force and safety factor during construction. The research shows that the bending moment of the v-shaped tunnel is about 23.3 6 kN · m, and the I14 steel support just meets the bending resistance requirements. The bending moment of the viaduct tunnel dome is about 56.6kN · m. The stability of the surrounding rock of the tunnel can be ensured by using the I18 steel support or the double I14 steel support. The research results will provide a theoretical basis and references for the design and construction of the steel support for large deformation tunnels of soft rock under high ground stress in the future.