Use of Grouting to Control Horizontal Tunnel Deformation Induced by Adjacent Excavation

Abstract

A grouting technique is introduced as a measure to protect tunnels adjacent to a large-scale excavation. Field measurements indicated that this grouting technique reduced the maximum horizontal displacement in the tunnel from 9.2 to 4.6 mm. Based on this application and two field tests, the following recommendations are proposed: (1) the upper boundary of the grouted zone should be set at or below the tunnel; (2) grouting holes should be installed 3–4 m from the tunnel and at an interval of the length of a tunnel ring along the tunnel axis; (3) in a row of grouting holes, grouting should be conducted at an interval of six to eight holes in a day, and the grout volume per hole should be small, such as 0.5 m3; and (4) when using multiple rows of grouting holes, a far-row-first grouting scheme, in which the grouting sequence progresses toward the tunnel, should be adopted.