a. Department of Geosystem Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan

Authors had proposed two types of constitutive equations which were developed based on the experimental data of some Japanese rocks. Since proposal of the equations, a lot of questions were asked us by researchers and engineers who took part in construction of tunnels, underground storages and so on.
Through the discussion with questioners, it was found that there were many common points in questions, especially on how to obtain the parameters in the equations, which arose mainly because explanations and assumptions concerning the constitutive equations were changed many times and it was hard for readers to understand the whole systems starting at experimental work, through determination of parameters, and ended at numerical simulation and evaluation of the calculated results.
In this manuscript, we tried to explain the present constitutive equations in the form of FAQ (Frequently Asked Question), which was chosen for convenience of busy readers. A variable-compliance-type constitutive equation is mainly stated, however, most questions aad answers are also applicable to other types of equations with slight modifications.