THE LOOSING PHENOMENON IN THE SAND GROUND BY EXCAVATION OF CLOSE PARALLEL SHIELD TUNNELS

Abstract

This research is to clarify the mechanism of the loosing phenomenon of the surrounding ground as a long-term influence by the excavation of the close parallel shield tunnels. The research examined the effect of loosing quantity by the occurrence of tail-void and the effect of distance of the parallel tunnels. The model experiment was conducted, in which aluminum rod mass using two tunnel models was applied as a simulated ground, and the simulation analysis by distinct element method (DEM) analysis was done. As a result, the soil pressure that was on the first tunnel increased by the influence of excavation of the second tunnel, and the ground arching effect which strides over two tunnels was confirmed. Moreover, the results of analysis and experiment were also compared with measuring results in the construction.