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.