LAUSR

Large-diameter buried steel pipes (BSPs) play critical roles in water transport for major water diversion and hydropower projects. Due to poor pipe-soil composite system properties and installation conditions, they are prone to excessive deformation, resulting in safety hazards. This paper takes a BSP project subjected to excessive deformation as an example. A simplified numerical model is first established to analyze the structural performance, including the stress and plasticity, and the relationship between the stress and deformation of the pipe. Furthermore, a jacking method to rehabilitate the pipe-soil composite system is conducted to explore its influences on pipe deformation, stress, and plasticity. The results show that considerable bending stresses occur in the pipe and that sections of the midspan and stiffening ring are in the pure bending state and eccentric bending state, respectively. Areas of high stress and plasticity center at the crown, springline, and invert of the pipe, and steel pipes with ring deformation of 8.9% can be continued to be used, as the full yielding of the pipe walls occurs at the ring deformation of 15.8%. The jacking method is an effective solution for the rehabilitation of BSPs subjected to large deformation and can reduce pipe deformation significantly while increasing the stress at the pipe crown and the pipe plasticity only slightly.