Abstract: Taking the skarn specimens extracted near the deep ore drift in Dongguashan copper mine as the research object, a modified split Hopkinson pressure bar (SHPB) system was used to investigate dynamic characteristics of deep skarn under the combined action of high axial pressure and confining pressure under frequent dynamic disturbance. The results show that internal microcracks in specimens were closed due to high pre-loaded axial pressure and confining pressure, which results in no concave phenomenon at the initial stage of dynamic stress-strain curves during the impact load, i.e. no compaction stage. After peak stress, the phenomenon of reduced strain rebound occurs when the elastic force stored in the specimen is greater than the impact load during unloading. Otherwise, the compressive strain increases until the specimen breaks. The accumulative impact disturbance times rises while with increasing confining pressure, and it reduces due to the increased axial compression. Furthermore, the growth or decreasing rate is influenced by the confining pressure and axial pressure. The dynamic deformation modulus and peak stress decrease with the increase of impact disturbance times, but the maximum strain and dynamic peak strain grow up. Moreover, the average of dynamic strength has been cut down with the rising axial pressure, but it decreases firstly and then increases with the increase of confining pressure. The dynamic deformation of rock is accompanied by elastic deformation, the strain rebound generally increases firstly and then decreases with increasing impact disturbance times on the whole.

Key words: high axial compression, confining pressure, dynamic disturbance, deformation characteristics, impact times, deformation modulus