Abstract
Recently, NATM method has been adopted in tunneling under shallow and unconsolidated ground. In order to stabilize the face and control the ground surface settlement, a variety of forepiling methods have been proposed. Above all, long-sized forepiling is evaluated as the effective one for its ability to reinforce the ground. However, this method is not economical, and has a bad influence on the total construction period. Therefore, authors proposed a new forepiling method using middle-sized forepiling as the more effective one, based on a series of laboratory tests. In this paper, the outline of this new method, the results of laboratory tests and its application to actual work are presented.
