Abstract:

 In recent years, more and more shieldbored tunnels are adopted in Metro works. For the sake of curves, standard rings and turning rings are installed so as to fit the tunnel alignment. A curve is composed of a circular curve and two transition curves. The segment arrangement on circular curves has proven theoretical support; the segment arrangement on transition curves, however, has no theoretical support and is usually executed by means of VMT systems equipped on shield machines. On basis of the relevant survey theories and the actual conditions of the turning rings, the author probes into the segment arrangement on transition curves in the paper.