TUNNEL EXCAVATING MACHINE

PURPOSE:To make excavating forward even a collapsible ground or a sort ground having a large deformability by pushing out a cutter head ahead in axial direction along with the base, furnishing a push/pull means to draw the rear shell to the body rushed out, and providing a pressurizing means to expand or contract the outer shell in the radial direction. CONSTITUTION:In the condition that the front shells 20, 10 solely are expanded and to hold the surface to be excavated, only a front shell jack 23 is elongated, and excavation is carried out forward while reaction force is obtained from the tunnel side wall W through the front shell 20 expanded. Then a rear shell jack 13 is contracted, and the rear shell 10 is drawn toward the front shell 20. When the front shell jack 23 attains its stroke limitation, only the rear shell jack 13 is elongated to serve in the condition that the rear shells 10, 20 are expanded, and excavating forward is made while reaction force is obtained from the tunnel side wall W through the expanded rear shell 10. The front shell jack 23 is contracted, and the front shell 20 is pushed out forward. When this causes expansion of the rear shell 10 and front shell 20, the tunnel side wall is pressurized, so that a reaction force to push out the cutter head 40 can be obtained therefrom, and at the same time, the tunnel side wall can undergo timbering work.