The buckling of liners carries significant implications, including hampered medium transmission, structural damage, and the risk of leaks, adversely affecting production, economy, and the environment. The interface performance between Cured-in-place-pipe (CIPP) liners and host pipes is pivotal for overall structural stability. However, this interface ’ s influence has been underestimated in engineering practices and laboratory research. This study introduces two novel hydrostatic pressure buckling models, enhancing constrained arch and energy based Glock models, while considering both free and bonded boundary conditions. Subsequently, a validated 3D finite element model of CIPP lined pipes is established from full-scale tests. Through comprehensive sensitivity analysis, the study investigates the influence of diameter-to-wall thickness ratio (DR) and annular gap on liner buckling under free boundary conditions. Additionally, it explores the effects of DR value and ovality ratio on buckling behavior under bonded conditions. Results reveal distinct buckling and post-buckling modes under different boundary conditions. The proposed theoretical analysis method accurately predicts critical buckling pressure within a 10 % error margin, validated through experiments and numerical simulations, offering prac tical guidance for assessing repaired pipe stability.

In pipe jacking, the continued growth of friction resistance around the pipe may cause problems, such as an insufficient jacking force, soil collapse, and even land subsidence, which seriously endangers the structural safety of the pipe and surrounding structures. Bentonite slurry is often used as a lubrication material, but the friction resistance increases due to the inappropriate slurry concentration, and this may cause construction safety problems. In addition, the slurry standing time increases the difficulty of re-jacking construction. To further study the above problems, the friction characteristics of a steel pipe-soil interface under different slurry concentrations and slurry standing times were studied using direct shear tests. The test results show that the peak shear stress and friction coefficient of the interface first decrease and then increase with the increase in the concentration, which is less than or equal to 20%. The peak shear stress and friction coefficient increase with the increase in the concentration, which is greater than 20%, and the position of shear failure changes from between the slurry soil mixture and pipe wall to between the slurry and pipe wall, and finally to the slurry interior. The influence of the slurry standing time on the friction characteristics of the interface is as follows: For the same slurry concentration, the peak shear stress and friction coefficient of the interface increase with the standing time, approximately increasing first and then stabilizing; for different slurry concentrations, the amplification of the peak shear stress and friction coefficient increase with the increase in the concentration.