| 摘要 |
PURPOSE:To reinforce a tunnel facing and stabilize the facing by radially drilling the ground along the outer periphery of the excavated hole of the tunnel facing while injecting a soil improving agent to form an agent injected layer having a T-shaped section. CONSTITUTION:In the excavating operation of facing of chiefly sandy soil, the inside of the facing 3 is drilled by a drilling machine 2 from a tunnel hole 1 and the agent injecting pipe 6a of a soil improving agent injecting device 6 is inserted into drilled hole portions radially provided on the outer peripheral portion of the tunnel hole 1. Agent injecting ports are provided on the agent injecting pipe 6a in three directions nearly perpendicularly intersecting to the axis thereof and, while drawing out the injecting pipe 6a at a defined speed, a defined quantity of soil improving agent is injected to form an agent injected layer having a T-shaped section. Thereby, the break down of the sandy soil facing or crest can be prevented. |
