Tunnelling shield advancing system - uses concrete injected behind linings as pressure surface for advancing cylinders

摘要

The tunnelling shield advancing method, uses a shield which has an outer shell (8) which is the diameter of the tunnel being formed, and a inner shell (7) inside which the tunnel lining sections (3) are located, and from which they are discharged. Around the inner shell is a set of holes (5) through which granular material (6) e.g. concrete is injected so that it fills up the annular space between the linings and the tunnel wall (4). the shield is then advanced by lescopic cylinders (2) housed between the outer shell and the inner shell, the rear part of the cylinders exerting pressure on the concrete filling, and the front part exerting pressure on plates forming the framework between the shells.