Outline of underground research roadway of Horonobe deep underground research program and its support design

The results of underground research roadway design of Horonobe deep underground research program are as followings; 1) the core observation and analysis of rock experiments data made clear to generate discontinuous behavior originated from crack, 2) the strength and elastic coefficients of rock are determined under the consideration of effects of crack, and 3) the double support structure was introduced into dig of underground under the conditions of rock with small strength. The underground environment, execution method, determination of various constants of rock, analytical model of support, support materials, estimation of stability of rock around cavity, double support structure, and discussion are reported. (S.Y.)