Study On The Attenuation Law Of Blasting Vibration In High-section Quarry And Its Influence On The Filling Body

In the process of underground mining of metal mines,blasting is the main means to break the rock,but at the same time,it also brings some negative effects.Like blasting seismic wave is the main factor that causes vibration of surface building(structure)and damage of filling body,effective control to reduce the hazard of blasting seismic wave can improve the safety benefit of mine production,reduce the mixing of filling body during re-mining and improve the re-mining efficiency of mine.The existing safety criterion is defined based on the peak vibration velocity of the mass,so it is meaningful to study the decay law of the peak vibration velocity during the propagation of blasting seismic waves to control the hazard of blasting seismic waves.In this paper,based on the decay law of peak vibration velocity during the propagation of blasting seismic waves,a more in-depth study on the decay law of peak vibration velocity during the propagation of seismic waves and the impact on the filling body was conducted by using a combination of field monitoring and numerical simulation in the background of deep hole blasting in the actual mining site of Li Lou iron ore mine.Through on-site field research,the monitoring locations of peak vibration velocities at the surface and downhole were determined.The monitoring of three-way vibration velocity and analysis of the decay law of local blast vibration velocity to obtain the maximum single-section blasting charge is the theoretical basis for carrying out blast vibration reduction design.Based on the traditional Sadovsky nonlinear fitting formula,which is the most representative and the most instructive in the field despite the poor fitting effect,this paper introduces the equivalent vibration speed to quantitatively describe the decay rate of vibration speed,and ranks,classifies and fits the linear regression to the monitoring data according to the decay rate of vibration speed,and obtains the Z-way 1linear regression formula with the slowest decay rate of vibration speed.The results show that the blast speed regression formula proposed according to the blast speed decay speed,its regression correlation(R2=0.9009)is much higher than the traditional non-linear fitting formula(R2=0.3915).And its scientific rationality was verified by the field monitoring data,which provided an important theoretical basis for the blasting vibration reduction design of Li Lou iron ore mine.In view of the influence of two-step back mining on the filling body,a numerical model conforming to the two-step back mining room of Li Lou iron ore mine was constructed according to the actual mining room parameters and filling body parameters.The numerical simulation study of its on-site production blasting was carried out by finite element software LS-DYNA to analyze the impact of blasting on the adjacent filling body,and finally verified by on-site industrial tests.The simulation results show that: with the increase of charge density,the maximum impact range of stress wave increases from 2.79 m to 3.91m(from the junction of filler and ore body),and the phenomenon of local filler spalling exists;the peak effective stress within the filler is proportional to the charge density,and the peak effective stress is 1.176 MPa at a charge density of 0.9 g/cm3,while the peak effective stress is 1.8 MPa at a charge density of 1.8 g/cm3.At a charge density of 0.9 g/cm3,the peak effective stress is 1.176 MPa,while at a charge density of 1.8 g/cm3,the peak effective stress is 1.457 MPa,an increase of about 23%.The peak effective displacement at the selected point is proportional to the charge density,i.e.,the peak effective displacement gradually increases with the increase of charge density.For example,when the charge density is 0.9 g/cm3,the peak effective displacement is 0.265 mm,while when the charge density is 1.8 g/cm3,the peak effective displacement is 0.349 mm,an increase of 31%.According to the equivalent damage principle of effective displacement: when the displacement value is in 0.1～0.3 mm,the unit at the position is considered to be more affected or less damaged;when the displacement value reaches0.3～0.9 mm,the unit at the position is more damaged or destroyed;when the displacement value exceeds 0.9 mm,the unit at the position is irreversibly damaged.It can be seen that when the charge density is 0.9～1.2g/cm3,the effective displacement value is 0.26～0.29 mm,and the filling body is greatly affected,but there is no big damage;when the charge density increases to 1.5～1.8 g/cm3,the effective displacement value is0.32～0.35 mm,which indicates that the filling body has been greatly damaged,and although there is no damage,it is highly Although there is no damage,it is very likely to cause local spalling or collapse,which will affect the output grade.The vibration monitoring data on the surface is within the safe range when blasting at the designed maximum single section charge through the field test calibration.The peak vibration velocities at the boundary between the fill and the ore body were also found to be within the safety limits by fitting the data to the seismic wave attenuation law in the fill.