PROPOSAL OF ROCK MASS BEHAVIOR CLASSIFICATION BASED ON CONVERGENCE MEASUREMENT IN SHAFT SINKING THROUGH SEDIMENTARY SOFT ROCKS

Abstract

  Japan Atomic Energy Agency has been excavating deep shafts through sedimentary soft rocks in Horonobe, Hokkaido. From the viewpoint of the observational construction, site engineers need a practical guide to evaluate the field measurements conducted with shaft sinking. The author analyzed the relationship among initial deformation rate, observed deformation, the ratio of the modulus of elasticity of rock mass to the initial stress, and the magnitude of inelastic behavior of rock based on convergence mearsurements and investigation of rock mass properties on shaft walls. As a result, the rock mass behavior classification for shaft sinking which consists of three classes was proposed.