Abstract: Deep rock mass is in the complex environment of " three high and one disturbance ".In order to study the influence of impact load on roadway surrounding rock during roadway excavation,limestone is taken as the research object,and the mechanical properties of limestone under three-dimensional dynamic and static combined loading are studied through the improved SHPB dynamic and static combined loading test device of Henan Polytechnic University.Typical axial pressure gradients (8,15,16 and 17 MPa) and circumferential pressure gradients (1,2,3,5 and 7 MPa) were selected,and three-dimensional combined loading tests with impact pressure gradients (0.5,0.6,0.8 and 1.0 MPa) were carried out.The results showed that the peak strain of limestone increased under the three-dimensional combined dynamic and static loading,and the absorbed energy also increased,with the peak value reaching 87.7 W/J,which was about 60% of the incident energy,and the fragmentation of the specimen was the most obvious,showing the trend of "rock burst" in the laboratory.The reflected energy,transmitted energy and absorbed energy increased linearly with the increase of incident energy,increased linearly with the increase of incident energy.The reflected energy,transmitted energy,absorbed energy,incident energy and absorbed energy per unit volume increased as a quadratic function with the increase of the average strain rate.In addition,when the axial pressure and confining pressure remain unchanged,the stress-strain curve is divided into four stages with the increase of the impact pressure.When the strain reaches the peak value,there is a rebound phenomenon,that is,the strain begins to decrease after the deformation of the sample reaches the peak strain.The variation law of the stress-strain curves when the confining pressure and the confining pressure remain unchanged is basically consistent with that of the impact pressure when the axial pressure and the confining pressure remain unchanged.The failure modes of rock under different confining pressures are mainly tensile failure and compressive shear failure.

Key words: three-dimensional dynamic-static combination,mechanical properties,energy dissipation,stress-strain