Study On Mechanical Properties And Damage Mechanism Of Rock Subjected To Coupling Action Of Impact Loading And Real-time Temperature

Rock is aggregate of natural minerals formed by various geological processes.There are more and more engineering cases involving the mechanical properties of rock under high temperature,such as the exploitation and utilization of geothermal resources,the exploration and exploitation of deep minerals,the deep disposal of nuclear waste,and the underground storage of carbon dioxide.These projects require high temperatures.These project constructions require in-depth understanding of the rock dynamics at high temperatures.This article uses the method of indoor experiment,theoretical research and numerical simulation to carry out the work,the specific content and related conclusions are as follows:Firstly,the impact compression tests of granite under different real-time temperatures were carried out based on the improved split Hopkinson pressure bar.It is found that the complete stress-strain curve of granite display three notable stages of elastic,plastic and strain-softening in the range of 20-500 ?.When the temperature rises to 700 ?,the plastic yielding platform in the curve appears.The increase of strain rate increase the energy absorption capacity per unit volume,the peak strength and peak strain of rock.The effect of strain rate on elastic modulus of rock is not obvious.The failure mode of specimen under the increasing strain rate at 500 ? and below change from the axial splitting to fracturing.At the temperature of 700 ?,all the specimens were pulverized.Then,considering strain rate effect of rock,a statistical damage model of rock under real-time temperature was established based on the Weibull distribution.The results show that the proposed statistical damage constitutive model can accurately describe the influence of temperature and strain rate on rock stress-strain behavior.The four constitutive parameters(m,DI,?0,?)all have clear physical meanings and the determination method is simple.The model can well reflect the stress-strain behavior in the whole process of rock failure,and the predicted results are in good agreement with the experimental data.Finally,by using the software of ANSYS/LS-DYNA and the Holmquist-Johnson-Cook(HJC)model,the SHPB test of rock specimens under different temperatures(20 ?,100 ? and 200 ?)was simulated.The resultsshow that the microcracks in the peripheral area of specimen are prone to crack firstly at low loading rates,and the internal cracks can also be activated at the initial stage of higher loading rates.The HJC model can well characterize the rock failure process at different temperatures,and the proposed method of determining HJC parameters of is feasible and accurate.The numerical simulation can well reflect the mechanical characteristics of rock under the impact loading,illustrating the dynamic failure process of rock during loading.