Original paper(Vol.47 No.5 pp.495)

Numerical simulation for stress and displacement of stacked drift type tunnel by FLEM-DEM coupled scheme

Kiyama Hideo; Nishimura Tsuyoshi; Hasegawa Makoto; Fuchimoto Masaki

Abstract:This paper deals with FLEM DEM coupled scheme for the analyses of stress and displacement of geotechnical problems. The discontinuous domain in a given problem is modeled as a set of distinct element blocks of DEM. The continuous domain is partitioned by a finite difference grid as a FLEM grid. The FLEM, which is proposed by us, is one of the numerical methods that can be used to analyze large deformation problems. The two methods are coupled together by satisfying the equilibrium conditions of traction and continuity of displacement at interface between the two domains, at each iteration of the solution process. This means that the coupled scheme is well suited for considering joint slips and separation as well as large rotation and displacement of blocks.
Verification of the scheme is demonstrated through the analysis of a stacked drift type tunnel. The stacked drift type tunnel is a new one which is now under investigation as a large cross section tunnel over 20m in diameter. The numerical results of the contact force between the drifts and force acting to the tunnel as well as the stresses in the surrounding ground are summarized together with the results from a series of centrifugal tests of the tunnel model. It may be concluded that the circumferential forces acting to the drifts are important to understand the stress displacement relationship of tunnel.

Key Words:FLEM, DEM, stacked-drifted-type tunnel, earth pressure, deformation