Dynamic Strain Rate And Dynamic Characteristics Of Backfill Subjected To Near-field Blast Wave

In the process of two-step in backfill mining method,the backfill body is inevitably influenced by the explosive stress wave from blasting mining,and the blasting disturbance caused by the stress wave on the backfill body will destroy the stability of backfill body,that destabilizes it and destroys it.In order to study the dynamic characteristics of backfill,the dynamic characteristics and damage process of backfill under blasting in two-step were studied by theoretical analysis,experimental study and numerical simulation.1)to calculate the loss of stress wave in back and transmission at the interface between rock and backfill and the strain rate of backfill under blasting dynamic load.2)the separated Hopkinson pressure bar was used to carry out uniaxial impact tests at different velocities to study the mechanical characteristics of the backfill under dynamic loading.The dynamic peak compressive strength of the backfill increases with the increase of the dynamic strain rate,and the strength growth factor increases first and then tends to be stable.The dynamic peak compressive strength of the backfill increases with the increase of the dynamic strain rate.When the strain rate is less than 50 s^-1,the main failure mode is fine crack,and when the strain rate is more than 50s^-1,splitting tensile failure will occur.3)based on experimental data,impact simulation of backfill was carried out to analyze crushing process and damage variables of backfill.Under uniaxial impact,failure of the backfill is mainly in the form of tension and compression,under static and dynamic combination,the backfill is first subjected to shear stress,then is crushed.DIF with strain rate under dynamic and static loading is lower than that under uniaxial loading.At low strain rate,damage variables of three kinds of backfill are similar,at high strain rate,the damage variables of 3MPa backfill are higher than those of middle and low level confining pressure.4)simulate the dynamic characteristics of backfill under rock blasting in the process of stoping,and verify that the maximum loss transfer of stress wave at different interface is 20%.The strain rate is calculated by extracting the vibration velocity time-history,and the dynamic load characteristics under different strain rates are analyzed.Figure 41,Table 16,Reference 77...