关键词: 爆破开采, 岩体, 数值模拟, 渐进破坏, 损伤因子

Abstract: Based on Landau firing blasting model and strain softening shear tensile composite constitutive model in Continuum-discontinuum Element Method（CDEM)，the relationship between blasting mining and damage fracture degree of rock mass surrounding the bore hole is discussed.According to dimensional analysis，the major influence factors related to the damage and fracture process of rock mass under blasting load are determined.By adopting Mohr-Coulomb model and maximal tensile stress model considering strain softening effect，the relationship between damage factors of rock mass and blasting distance under different cohesion and tensile strength is studied.Numerical results show that，a dense fracture zone with compressive shear failure appears near the bore hole，and the rock mass in this zone is totally damaged.In the area far from the hole，the major failure pattern is tensile failure，and some straight tensile fractures appear in this area.With the increase of blasting distance，the damage factor decreases gradually with decaying exponential pattern，and the fitting function between damage factor and dimensionless blasting distance，dimensionless cohesion and dimensionless tensile strength is obtained.The critical radius of strong damage region（the area damage factor greater than 0.9) varies about from 2.5 m to 5.5 m，only controlled by cohesion.The critical radius of weak damage region（the area damage factor less than 0.1) is generally greater than 8 m，and controlled by cohesion and tensile strength.

Key words: Blasting mining, Rock mass, Numerical simulation, Progressive failure, Damage factor