This article points out each of the current analytical methods used in CT mechanics of rock and soil avail of observation, wasting the precious quantitative information of CT datum. Based on the conception of the intercepted section in the damage-fracture space, utilizing the knowledge of the set theory, the measure theory and the Lebesgue integral, the rock and soil material is classified as the safety zone, the damaging zone and the fractured zone. The problems such as the upper and the lower boundary surface of the damaging zone, the relative length of the fractured zone, the number and the space size of the cracks in the fractured zone are studied. Meanwhile, the paper defining the rules of compressing and expanding, establishing the rock and soil mass constitutive relation of the divisional damage-fracture space, simultaneously furthering to deduce the basic equation of the rock and soil damage-fracture space theory. If the damaging zone is merged into the safety zone or the fractured zone, the constitutive relation of the divisional damagefracture space degenerates into breakage mechanics for geological materials presented by zhujiang Shen academician.