<p>Rectangular pipe-jacking tunnels are highly prone to longitudinal deformation under the influence of adjacent engineering activities, uneven foundation settlement, and changes in surface loads. These problems may lead to structural damage at the joints of rectangular pipe-jacking tunnels, potentially triggering engineering disasters. In response to these situations, this paper experimentally studies the effects of different foundation conditions and steel sleeve ring design parameters on their shear stiffness and rotational stiffness. It reveals three stages of joint failure: gap closure, steel sleeve ring stress, and deformation failure. A three-dimensional refined numerical simulation method is adopted to study the deformation and failure characteristics of joints under different foundation strengths and steel sleeve ring design parameters, analyze the mechanical performance of the joints of rectangular pipe-jacking tunnels, and verify the reliability of the experimental results. Based on the experimental and numerical simulation results, considering the nonlinear characteristics of the joints of rectangular pipe-jacking tunnels, a shell-joint theoretical model is constructed. Precise simulation is achieved through the combination of ‘rotation + shear’ dynamic elements, and the stiffness matrix at the joints and the calculation method of mechanical elements are derived. The shell-joint theoretical model is used to compare and verify the results of the joint tests of rectangular pipe-jacking tunnels, confirming the accuracy and practicality of the shell-joint theoretical model.</p>