Behavior of Surrounding Soil during Construction and Its Countermeasures Using Pipe Jacking Method in Deep Strata

Abstract

In Japan when urban infrastructures need to be constructed, the difficulty of utilizing the ground or shallow strata will lead to a more frequent use of the deep strata. The common construction methods are open-cut, pipe jacking, and shield methods. In recent years, a new pipe jacking method has been established that can be adapted to 20 m below the ground or more. Using this method, the drivage machine and the jacking pipe continue to move an underground until the completion of the driving. Therefore an over-cutting area (so-called tail-void) must be formed to lower the friction between the ground and the pipe. The tail-void is filled with lubrications. However, because the stress release from the ground continues to advance when the tail-void is formed, hence there are some challenges required to cope with the stability of the surrounding ground. In order to utilize the pipe jacking method in the deeper strata layers, the theory, analysis and installation of tail-void have to be systemized, and such systematic data must be stored. Therefore, the conditions of tail-void in the deep pipe jacking method are discussed using numerical analyses.