Yossef H Hatzor

This chapter describes the particular procedures used to determine and describe the critical blocks for a given free face. The input data are the data on orientation for the major discontinuities, their distributions of spacing and their frictional resistance. After explaining the analytical procedure, predictions are made with the actual block movements described for a tunnel driven through a discontinuous rock mass. The excavation is followed in all of its phases, beginning with a study of the geological exploration data, through a careful observation of block failures in a complete pilot tunnel and finally with an investigation of the full size excavation. -from Authors