BEDROCK REINFORCING METHOD

PROBLEM TO BE SOLVED: To provide a bedrock reinforcing method for developing a uniformly stable hardening layer in a bedrock required for stability, when a tunnel is excavated. SOLUTION: The bedrock reinforcing method is constituted of a perforated pipe setting process for setting a perforated pipe (2), having a large number of grout injection holes (3); consolidation process for consolidating (Co) circumferential bedrock (G) of the perforated pipe (2); a first bedrock stable process for injecting a grout (Jm) in the outside of the front end of the perforated pipe (2), by inserting a grout injection pipe (4) for injecting a longer packer (7) and the grout (Jm) into the perforated pipe (2) to place; a second bedrock stable process for injecting the grout in the outside of the perforated pipe (2) by pulling back the longer packer (7) and the grout injection pipe (4) to the (Co) side to place again and a bedrock stable repeated process for stablizing the bedrock, by repeating the same procedure as that of the second bedrock stable process.