Bending Performance and Parameter Influencing Mechanism of Spatial Reticulated Grid Joint Components in Mined Tunnel
To solve the technical problems concerning deformation control of tunnels surrounded by soft and weak rock,as well as meet the support requirements of high bearing capacity and high stability,a new type of prefabricated spatial reticulated grid(SRG)support structure was developed.As the weak part of the whole ring structure,the mechanical properties of the joints are crucial to the accurate evaluation of the overall bearing performance.To determine the difference in performance of different joint types,indoor full-scale tests and numerical simulations of pure bending of bolted endplate joint,combined sleeve joint,and jointless components were carried out for SRG arches.The deformation process and failure modes of each component were compared and analyzed,the bending moment-curvature function equation was established,and the bending stiffness and bearing capacity of the joints were evaluated quantitatively.The influence of endplate thickness,sleeve length,steel tube wall thickness,and other parameters on the mechanical properties of bolted endplate joint,combined sleeve joint,and jointless components were comprehensively analyzed,the influence mechanism of joint parameters was clarified,and reasonable parameters and design suggestions for arch joints were proposed.In addition,the field application of SRG arches was investigated considering on the Guangzhou Metro underground excavation tunnel project.The results show that the bolted endplate joint has high toughness and bearing capacity,the clear transmission of the joint force system during the loading process,stable deformation,and can be used as the preferred joint type for SRG arches.The combined sleeve joint has good ductility and post-deformation capability,and the combined sleeve is in good condition without significant deformation.The yield load capacity of the bolted endplate joint component increases significantly when the thickness of the endplate increases from 15 to 25 mm,resulting in a corresponding increase of 14.6％.The difference in yield load capacity between the joint components with the"top 3 bottom 4"and"top 5 bottom 6"bolt arrangements is only 3.1％.Compared with lattice girder,the integrity of the SRG arches is enhanced,and the surrounding rock control effect is significantly improved,with 31.6％and 31.4％reduction in arch top settlement and perimeter convergence,respectively.The results of this study can provide a reference for the design and construction of similar projects in the future.
万方数据
维普
