As one of the trenchless technologies for municipal underground infrastructure, pipe jacking has been widely adopted in the construction of underground culverts, utility tunnels, underground passages, and other structures. Compared with the traditional open‑cut method, it possesses remarkable advantages including no road excavation, negligible traffic disturbance, absence of surface dust and noise pollution, high construction speed, and low comprehensive cost. During trenchless pipe jacking construction, the jacking force supplied by jacking equipment is required to overcome the frontal resistance ahead of the cutterhead as well as the pipe-soil friction. The variation of frontal resistance remains limited under relatively stable geological conditions. Nevertheless, the pipe‑soil friction increases considerably with greater burial depth, larger pipe diameter, longer jacking distance, and more complicated jacking trajectory, which becomes a critical factor restricting the safe and efficient implementation of pipe jacking projects. Accordingly, effective mitigation of pipe soil friction represents an urgent technical challenge. In practice, lubricating slurry is commonly injected into the annular gap between pipe sections and surrounding soil for pipe-soil friction reduction, and the quality of the formed slurry jacket directly dominates the friction reduction performance. Using a self‑developed multi‑functional test platform for pipe soil friction in trenchless pipe jacking, this study investigates the influences of structural parameters of grouting holes on slurry jacket morphology and pipe soil friction under grouting‑lubrication conditions, and an optimization scheme for grouting holes arrangement is obtained. Meanwhile, the grooved bionic pipe sections are proposed based on engineering bionics, and their friction reduction performances and mechanisms are all explored. Experimental results reveal that the friction reduction ratio of the grooved bionic pipe reaches 28 % in dry sand, and increases to 63 % with grouting lubrication. This presentation provides references for enriching structural‑design approaches for pipe sections, advancing theoretical studies on pipe jacking, and guaranteeing the practical performance of pipe jacking construction.

Trenchless pipe jacking,Pipe-soil fricion,Grooved bionic pipe sections,Grouting holes,Friction reduction mechanisms