Abstract:  To study the shear stiffness characteristics of rectangular pipe jacking Ftype socket joint, a refined threedimensional finite element model is established. By analyzing the mechanical characteristics of joint members under different shear displacements, the shear stiffness of joint and the factors influencing the shear stiffness are studied. The results show the following: (1) The shear stiffness of Ftype socket joint in rectangular pipe jacking tunnel is nonlinear, which can be divided into three stages, i.e.〖KG-*3〗, when the dislocation amount is less than 7.6 mm, the shear stiffness of the joint is basically unchanged; when that is 7.6 ~ 22.29 mm, the shear stiffness of the joint is reduced to 30%; and when that is more than 22.29 mm, the joint reaches yield load, and the shear stiffness of the joint is basically 0. (2) First, the shear failure occurs to the steel collar of joint inverted triangle area, then compressive failure occurs to the concrete of joint inverted triangle area, and finally a failure surface is formed. The steel collar and concrete of joint inverted triangle area bear most of the shear force when joint dislocates, which is prone to failure and should be strengthened. (3) The shear stiffness increases with an increase in thickness and length of steel collar, chamfer radius, coefficient of foundation bed, and wall thickness, and the wall thickness has a most significant effect on joint stiffness.

Key words: rectangular pipe jacking, F-type socket joint, shear force, shear deformation, shear stiffness