Development of a dynamic true triaxial electromagnetic Hopkinson bar system

Subsurface rock masses and rock engineering are subjected to multiaxial static stresses and often also bear additional multi-directional dynamic disturbances generated by seismic activity, blast waves and vibration, etc. It is therefore of great importance to study and understand the dynamic mechanical behaviors and failure mechanisms of rocks under multiaxial and multidirectional dynamic disturbances for the scientific design, safe construction and stable operation of rock engineering. In view of this, a novel dynamic true triaxial electromagnetic Hopkinson bar (DTEHB) system is proposed and developed in this paper. It offers a cutting-edge testing platform for studying dynamic responses of rock masses, taking into account the coupled effects of three-dimensional dynamic disturbances with strain rates ranging from 10^1 s-1 to 10^3 s-1 and triaxial static in situ stresses. The fundamental principles, configuration and the technical challenges associated with the development of the DTEHB are introduced in detail. The viability and effectiveness of DTEHB were verified through an analysis of measured controllable and adjustable stress waveform data and an evaluation of dynamic true triaxial synchronized impact test results on coal specimens. The establishment of the DTEHB will facilitate experimental testing of rock and other materials under a range of dynamic disturbances, thereby advancing the theory of three-dimensional rock dynamic theories and its application in geotechnical engineering.