Joint Rock Impact Compression Experimental Research And Analysis

Natural rock is a complex medium containing a large number of discontinuous structures,such as joints,cracks and faults,and a variety of micro inclusions and pores.The joints have obvious weakening effect on the strength of rock mass,and the mechanical properties of jointed rocks is significantly different from the whole rock.Under the action of dynamic load,the strength characteristics,failure modes and energy characteristics of rock materials have always been important topics in rock mechanics and engineering.The study of dynamic mechanical properties of jointed rock under impact load will attract more and more attention.This paper makes 3 different jointed rock specimen which is with different number of joints,different joint angle and different plaster filling thickness by taking advantages of marble glue and plaster.Taking jointed rock as the main research object,the SHPB test system with spindle shaped bullet is applied to study the effect of different joints on dynamic compressive mechanical properties and energy dissipation of jointed rock under high strain rate.The main research content and results are as follows:(1)The physical parameters such as rock density and wave velocity were measured.The static uniaxial compression test of sandstone and gypsum specimens was carried out by using RMT rock mechanics test machine.The static mechanical parameters of the specimens were obtained,which provides a useful reference for jointed rock impact compression test.(2)Uniaxial impact compression tests of 3 different forms of jointed rock were carried out.After processing a lot of data and figures,the influence of different joints on dynamic strength,strain rate and failure form of specimens were analyzed.(3)The influence of 3 different joint forms on the energy dissipation of the specimen is studied.The variation law of the incident energy,the reflection energy,the transmission energy and the absorption energy coefficient in the SHPB test is analyzed respectively.As the number of joints increases,the energy absorption coefficient of specimens decreases.The energy absorption coefficient of single joint specimens with different inclination angles is greatly influenced by the dip angle of joints.The energyabsorption coefficient of specimens with different plaster thickness is relatively small,and most of the incident energy is converted into reflection energy.