BEHAVIOR OF BRACED EXCAVATIONS STABILIZED BY DEEP MIXING METHOD

抄録

In areas of Japan with a thick soft clay layer, the Deep Mixing (DM) method, which is one of the soil stabilization methods, is occasionally used for braced excavations. However, some excavations have been interrupted because of unusual behavior. This report analyzes data obtained from field observations during the construction for expanding the Tokyo International Airport. The main reason for stopping the excavation was not an increase in either the strut forces or the bending moments of the retaining wall, but the large heave of the vertical supports. Instead of using the circular failure method, which is extensively used to examine base failure in Japan, a new stability number, N_t, is proposed for braced excavations stabilized by the DM method.