Dynamic Brazilian Splitting Test And Numerical Simulation Of Water-saturated Layered Slate

In mining,oil well drilling,tunnel blasting and other production activities,rocks need to withstand impact loads at different loading rates,showing completely different mechanical properties from those under static loading.Studying the dynamic mechanical properties of rocks is important for the smooth progress of these projects.significant.In order to study the dynamic tensile mechanical properties and failure law of layered rock in saturated state,taking layered slate as an example,the dynamic Brazilian splitting test of slate was carried out on the Hopkinson pressure bar system（SHPB）.Combined with high-speed camera and numerical simulation,the specific research content and main conclusions are as follows:On the SHPB system,the dynamic Brazilian splitting test was carried out on the slate according to 7 different bedding dip angles（θ=0°～90°）,compared with the dry slate,and the dynamic tensile mechanical properties of the saturated slate were analyzed emphatically.The test results show that the dynamic tensile strength of both dry and water-saturated slate has a rate effect,which increases with the increase of loading rate;when the loading rate is lower than 395GPa·s^-1,the dynamic tensile strength of water-saturated slate It is lower than the dynamic tensile strength of dry slate;with the increasing loading rate,the dynamic tensile strength of saturated slate gradually exceeds the dynamic tensile strength,showing a more significant loading rate effect.The viscous force of water,the"Stefan"effect and the tension of the meniscus push the water-saturated slate to show higher strength.The dynamic tensile strength of water-saturated slate is higher when loaded atθ=75°and 90°;the response of dynamic tensile strength of slate to loading rate is greater than that to bedding.The energy dissipation law and failure mode of slate are analyzed,and the reasons for the difference in strength of specimens under different bedding dip angles are analyzed from the perspective of energy and failure mode.The results show that the dissipative energy density of both dry and water-saturated slate increases with the increase of loading rate;under the same loading rate,the dissipated energy density of water-saturated slate is higher than that of dry slate.When loaded atθ=75°and 90°,the dissipated energy of the specimen is higher than that of the other groups.When loaded at different loading angles,the failure modes of slate are significantly different;the failure of theθ=75°and 90°specimens is mainly the tensile failure of the slate matrix,so the strength is higher,and more energy is needed to achieve the overall failure.The finite element software ANSYS/LS-DYNA is used to simulate the dynamic Brazilian splitting test of slate,and the JH-2 constitutive model is used to describe the dynamic mechanical properties of the rock.The simulation results show that the peak of the stress waveform,the peak value of the dynamic stress-strain curve of the slate and the shape after failure are basically consistent with the laboratory test results,which proves the feasibility of the JH-2 model to simulate the dynamic tensile mechanical behavior of the rock.and the rationality of parameter calibration.The evolution paths of cracks under various loading angles are analyzed,and several modes of crack propagation are summarized.