隧道装配式空间网架螺栓端板节点力学特性及施工技术体系研究

Experimental investigation of mechanical characteristics of bolted endplate joint and construction technology system of prefabricated spatial reticulated grid arch in underground support

为解决复杂城市环境下浅埋大断面隧道施工进度慢、机械化程度低、安全风险高等难题,借鉴"及时支护,强支护"的控制理念,设计出一种高强度、大刚度的装配式空间网架支护结构。为明确该结构作为隧道初期支护的变形特性和力学机制,优化构造参数,该文综合考虑主肢钢管直径和壁厚参数变化的影响,开展空间网架螺栓端板节点构件的抗弯承载性能研究,就变形破坏形态、极限承载力、弯曲挠度及应力应变演化规律进行了深入分析。研究结果表明:在整个荷载-挠度历程曲线中,空间网架结构经历了弹性增长阶段、塑性发展阶段和最终破坏阶段;增加钢管直径和壁厚,均能不同程度上提高结构的极限承载力和抗弯刚度,改善构件的应力应变状态,其中钢管壁厚对新型支护结构的力学性能影响更为显著;现场试验表明空间网架整体受力呈现"上大下小""不均匀对称"的特点,拱肩及拱顶部位应力普遍较大,拱腰部位次之,下台阶拱脚最小;拱架安装机械化显著提升了立拱效率,提高了机械化作业水平,保障了施工安全。研究成果不仅丰富了地下结构支护形式,还为该结构在相关工程中的结构设计、参数优化及推广应用提供借鉴。

To solve the problems of slow progress,low mechanization,and high risk in the construction of shallow buried large cross-section tunnels in complex urban environments,this study designed a prefabricated spatial reticulated grid(SRG)support structure with high strength and large stiffness,based on the concept of“timely support,strong support”.To investigate the deformation characteristics and mechanical properties of the primary support in the tunnel and optimize the structural parameters,this study considered the influence of the steel tube diameter and wall thickness,and investigated the bearing capacity of the bolted endplate joint components of the SRG.The failure mode,ultimate bearing capacity,bending deflection,and stress-strain evolution law was analyzed.The load-deflection curves show that the SRG structure went through the elastic growth,plastic development,and ultimate failure stages.The ultimate bearing capacity and flexural stiffness of the structure improved to varying degrees by increasing the steel tube diameter and wall thickness,and the stress-strain state also improved.The thickness of the steel tube wall had a more significant impact on the mechanical properties of the innovative support structure.In the field test,the overall force of the arch frame exhibitedthe characteristics of“larger on the upside and smaller on the downside”and“uneven symmetry”.The stress on the arch shoulder and vault was generally larger,followed by the arch waist and the arch foot was the smallest.Mechanized installation can significantly improve the efficiency of arch erection and the level of mechanized operation,and ensure the safety and reliability of the construction.The results not only reveal the support types of underground structures,but also provide an important theoretical basis for the structural design,parameter optimization,and widespread application of this structures in related projects.