Study On The Influence Of Open-pit Mine Blasting On The Multi-story Frame Structure And The Techniques Of Reducing Blasting Vibration

With the development of China's open-pit mines,the exploitation of open-pit mines has continued to expand,resulting in the blasting operation area getting closer and closer to the surrounding buildings,and the speed response amplitude of the building is increasing,when the response amplitude exceeds the criticality.At the time of value,the structure will cause a certain degree of damage and destruction,so it is necessary to study the characteristics of the blasting seismic wave and the earthquake response law of the building.Taking the blasting of a cement limestone open-pit mine as the engineering background,blasting vibration monitoring was performed on surrounding buildings to obtain the blasting seismic wave waveform data of each measuring point,and the main frequency was statistically analyzed.Then the finite element software ANSYS and LS-DYNA were used.builds a multi-layer frame structure model,performs static analysis,modal analysis and transient analysis on the structure,changes the parameters of the input seismic wave,studies the influence of the three elements of the seismic wave on the multi-story frame structure,and finally analyzes methods for reducing blasting vibration.Based on the numerical simulation method,the vibration velocity of the particle under different time interval conditions was studied.The main research contents,research methods and research results include the following parts:(1)Design a blasting vibration monitoring program and statistical analysis of the main frequency of the blasting seismic wave signal to study the distribution rule of the main frequency of the blasting seismic wave.The results show that: the main frequency in the X direction is concentrated in the range of 25 Hz to 30 Hz,the main in the Y direction and the Z direction The vibration frequency is concentrated at 20 Hz to 25 Hz.(2)Using finite element software ANSYS and LS-DYNA to establish a six-story frame structure model,static analysis of the model to obtain the initial stress and displacement of the frame structure.The modal analysis of the model was performed to obtain the first six-order vibration modes and natural vibration frequencies of the frame structure.Their natural vibration frequencies were 2.988 Hz,3.393 Hz,3.7524 Hz,9.4075 Hz,10.472 Hz,and 11.611 Hz,respectively.Transient analysis of the model was conducted to simulate the influence of three-way blasting seismic waves on the frame structure.The simulation showed that the vertical vertical velocity,displacement was greater than the horizontal radial and horizontal tangential velocity and displacement,and played a major role in the destruction of the frame structure,and the velocity Displacement increases with the increase of the number of layers,showing a high magnification effect.(3)Using finite element software LS-DYNA to simulate the impact of one-way blasting seismic wave(Y direction)on multi-story frame structure,change the three elements of blasting seismic wave,and study the influence of velocity amplitude,frequency and duration on multi-story frame structure.The simulation shows that the response amplitude of the frame structure increases with the amplitude of the input seismic wave;when the main frequency of the seismic wave approaches the first natural frequency of the structure,the structural response value is the largest;in the elastic phase of the structure,the duration of the action does not Will change the response amplitude of the structure.(4)Based on the LS-DYNA software to optimize the millisecond blasting interval time,the research shows that when the millisecond blasting interval is 20 ms,the minimum speed is 0.2827cm/s.