Cyclical Dynamic Experiments Of Rock Under Static Stress And The Study Of Damage Properties

To provide theoretical and technological support for the understanding of rock mechanical properties under dynamic loads and the long-term stability evaluation of engineering rock mass, in this paper the dynamic experiments were carried out with single-pass and cyclical impact loads by using an innovative testing system. The dynamic mechanical properties of rock under different loads were studied. A statistical damage constitutive model for the rock under dynamic loads was developed. The evolution law of the damage degree of specimens were analyzed with the stress-strain curves. The main contents and conclusion are as follows:(1) The dynamic experiments under different cyclical impact loads were carried out. And the experimental results show that the original Young’s modulus of the stress-strain curves are equal. Along with the increase of circular action times of impacts, the modulus of deformation decreases, the accumulation strain increase and the yield stress shows decreasing trend. The impact strength of rock specimens increases because of the axial static loads.(2) The failure model of the four rock samples under cyclical loads were analyzed. The results show that:the failure mode of the rock samples was significantly related to the structural characteristics of the rock. With the increase of the static stress, rock samples internal damages were intensified.(3) The statistical damage constitutive model for rock was established which was based on Weibull random distribution. The way of calculating the model parameters was determined. The model curves are in accord with the actual curves, which shows the rationality of the model. It is found that the damage degree increases along with the increasing strain. At the peak of the stress-strain curve, the damage degree has an obvious inflection point. The maximum of the damage degree actually shows the deformation capacity of the specific material under the different loads, which is concerned with the maximum of the strain.