Abstract: This article presents each of the current analytical methods used in rock and soil mechanics through CT number research avail of observation, wasting the precious quantitative information of CT datum. Utilizing the set theory and the measure theory, the concepts of the λ level damage-fracture ratio and the λ level damage-fracture rate, the (λ1－λ2) level intercepted section ratio and rate are defined based on the CT number, simultaneously furthering to research the relation among the λ level damage-fracture rate, the CT number and the density. The position and damage-fracture criterion are studied. Based on the conception of the intercepted section in the damage-fracture space, the rock and soil material is classified as the safety zone, the damaging zone and the fractured zone, the upper and the lower boundary surface of the damaging zone are studied. Meanwhile, the paper defining the rules of intensifying and damaging, establishing the rock and soil mass constitutive relation of the divisional damage-fracture space, simultaneously furthering to deduce the basic equations of the rock and soil damage-fracture space theory.

Key words: &lambda, level damage-fracture rate, (λ1－λ2) level intercepted section rate, safety zone, damaging zone, fractured zone, constitutive relation of divisional damage-fracture space