| 摘要 |
The roof of a tunnel being bored by a tunneling machine is continuously supported, using sections of lagging and ring beams. A shield is positioned over the earth boring machine. The shield includes a multiplicity of elongated members. The elongated members provide elongated recesses that will accommodate sections of lagging. A length of tunnel is bored, and a ring beam is implanted in the tunnel beneath the shield. The lagging may be manipulated in the elongated recesses in the shield and positioned proximate the roof of the tunnel supported by the ring beam. Additional lagging is provided by repeating the steps. |
