Studies on the design method of multi tunnels in geological disposal facility, 2

Hayashi, Katsuhiko; Kobayashi, Yasushi; Hiramoto, Masayuki*; Mizutani, Kazuhiko*; Morita, Atsushi*

"Study on configuration of analytical domain of the multi tunnels model" and "Remainders on an elasto-plastic FEM (Finite Element Method) analysis" in case of the full width of pillar become plastic on simplified model" are studied as "The study on the enhanced reliability of elasto-plastic FEM". In addition, "The effect of rock support and consolidation of the host rock to control the plastic region" was conducted as "The study on the mechanical stability of tunnels". As the results, it was seen that the analytical domain should be assigned 3-5W (W: width of multi tunnels) for a horizontal side from the endmost tunnel and 3-4W for below of the tunnels. It was found reasonable and proper on the elasto-plastic FEM analysis that the analysis domain must be large enough not to have plastic deformation in all analysis of domains under the condition in which the full width of pillar has plastic deformation. It was also found that the ground support suppresses the plasticity domain as the ground support effect. It was acknowledged that the auxiliary construction method by improvement of the ground has the suppression effect of the plasticity domain applying to the multi tunnels.