A STATIC CREEP FRACTURE MODEL AFTER DYNAMIC DAMAGE IN BRITTLE ROCKS

The static creep characteristics of brittle rock under dynamic stress wave disturbance are of great practical significance to the evaluation of surrounding rock deformation in deep underground engineering. The localized damage of microcracks under dynamic loads can seriously affect the creep mechanical behavior of brittle rocks. Based on the relationship model between microcrack growth and stress, dynamic damage evolution function, dynamic-static load path function and viscoelastic constitutive model, a micro-macro mechanical model considering the creep fracture characteristics of brittle rock under the dynamic disturbance of stress wave is proposed. The dynamic damage is realized by controlling the initial microcrack number. This model describes the strain curve with time under stress wave disturbance, and then explains the creep failure characteristics of rock under stress wave loading. The strain-time relation curves of brittle rock under the influence of different stress wave amplitudes and periods are studied, and the rationality of the model is verified by the test results. The influence of the change form, the time of a sudden change and the magnitude of a sudden change for the dynamic damage on the creep failure characteristics of rock are discussed. The effects of the amplitude and period of stress wave on dynamic damage effect and creep failure characteristics of rock are analyzed. The main results: the larger the change value of dynamic damage, the shorter the creep failure time. The happened time and the increasing form of dynamic damage during impact loading damage have little effect on the strain and creep failure time of the rock after dynamic disturbance. The dynamic damage experiences an accelerated increase with the increment of stress wave amplitude and the decrement of the stress wave period. The larger the stress wave amplitude, the smaller the period, and the shorter the creep failure time of the rock.