Study on shear mechanical response of F‐type socket joint in rectangular pipe jacking with longitudinal connectors

Abstract A circumferential joint is a weak part of a rectangular pipe jacking tunnel and is prone to damage under uneven foundation settlement and adjacent construction disturbance. Consequently, it is imperative to install longitudinal connectors at the joints of rectangular pipe jacking. To date, research on the mechanical characteristics of rectangular pipe jacking joints with longitudinal connectors has been limited. This article investigates the shear mechanical response and deformation failure characteristics of rectangular pipe jacking joints with longitudinal connectors through joint testing and numerical simulation. The results show that the shear deformation of rectangular pipe jacking joints with longitudinal connectors can be categorized into four stages: initial stage, elastic stage, yield stage, and failure stage. The synergistic effect of the longitudinal connector and the steel ring results in a 24% increase in the shear stiffness of the joint, a 17% increase in the bearing capacity for shear, and a 68% reduction in the strain experienced by the steel ring. The deformation region of the longitudinal connector occupies 11% of its length, with the concentration of stress occurring in the two plastic hinges. The primary failure characteristics of the joint include steel ring chamfered bulges, weld cracking, bolt hole cracking, and roof concrete cracking. Setting a 45° oblique weld, incorporating structural steel bars at bolt holes and roofs, and enhancing the strength of longitudinal connectors can significantly enhance the shear capacity of joints and reduce damage to rectangular pipe jacking structures.