Study On Dynamics Properties And Wave Characteristics Of Filled Jointed Rock

The propagation of stress waves in rock joints is a complex process.When the joint filler reaches a certain thickness and cannot be ignored,not only the stress wave attenuation will occur,but also the transflective phenomenon will occur at the two interfaces of the joint,further affecting The stability of the rock mass.In order to explore the propagation law and dynamic mechanical response of stress wave in filling joints,this paper studies it from three aspects: experiment,numerical simulation and theoretical derivation.And the main research work is as follows:The experimental part was carried out by the separate Hopkinson pressure bar(SHPB)experiment.The impact test was carried out on the specimens with different thicknesses,different dip joints and different filling materials at three different rates.The joint thickness,joint dip angle and filling were discussed.The influence of material and impact rate on stress wave propagation,and the energy dissipation characteristics under dynamic impact are studied.In the numerical simulation,the ANSYS/LS-DYNA finite element software is used to simulate the SHPB impact compression process.The selection of the penalty function factor and the impact of the impact rate on the simulation results are studied.Compared with the experimental data,the consistency is obtained.The theoretical part deduces the stress expression of the stress wave after multiple reflections in different filling joints,and verifies the correctness of the experimental and numerical simulations for the primary transflective study of stress waves in the specimen,and analyzes the stress wave in depth.The analysis results show that the existence of filling joints makes the transmitted wave signal weakened,and the longer the joint thickness,the more obvious the anisotropy of the material will be,the higher the attenuation of the transmitted wave signal,and the lower the strength of the filling material.The more the transmission amplitude is reduced,the more obvious the weakening effect of the stress wave.When the incident wave propagates in the specimen with the joint width of 4 mm,the transmission capacity is obviously better than that of the specimen with10 mm,and the variation of the transmission coefficient of the two joint width specimens decreases with the increase of the joint inclination angle.At larger impact rates,the larger the joint inclination angle,the lower the peak strength of the specimen,the larger the joint inclination angle,the smaller the deformation of the rock-like specimen and the smaller the dispersion of the peak load.The type of surface contact is more suitable for the HJC material model with failure criterion.The error of the simulation result when the penalty function factor is 2.0 is the smallest.When the mechanical properties of the rock mass are close to the mechanical properties of the filled material in the joint,the stress wave can pass through the joint smoothly,and the number of reflections hardly works.When the mechanical properties of the rock mass and the joint filling material are different,The number of reflections has a significant impact.