Support design study for the Horonobe underground research facility in FY2003/2004

JNC (Japan Nuclear Cycle development inst) has been conducting the project called 'Horonobe URL project' in Horonobe-cho, Hokkaido, Japan. The aim of the project is to establish the scientific and technical basis for geological disposal on sedimentary rock. In the project, a underground facility with 500 m depth will be constructed. This report is summarized the results on support design of the planned underground facility based on the data obtained by the several borehole investigations from ground surface. Owing to rational support design, the detailed compartment of the input parameters for the stability analysis in surrounding rock at position of underground facility were made based on the results of borehole investigation in HDB-1, HDB-3, which were drilled near the position. Moreover, the idea of double support system was adopted in this study to minimize the support in underground facility. (author)