A method for driving curved pipe-jacked tunnels

Abstract Curved drives of pipe-jacked tunnels provide a very difficult problem. Pipe joints in curved sections are V-shaped, and thus the eccentric thrust should apply at the contact point. Cracking of pipes by the concentrated thrust and deviation in the first pipe direction due to insufficient resisting lateral pressure of soil are the two main technical problems in curved drives. Injection of chemical grout to increase resisting pressure is frequently applied but it is very expensive. The author proposed a new curving method called “the unit curving method” in which four joint-adjusters are installed between pipes. The joint angle is controlled by the adjusters and the thrust is also distributed uniformly in the four adjusters. The new method solved most of the technical problems in curved drives economically and performed many jobs successfully in actual construction sites.