Experimental Study Of Precise Delay Time Blasting Vibration Based On Concrete Slope Similarity Model

This paper takes the propagation characteristics of blasting seismic wave in rock slope as the research direction,relying on the Natural Science Foundation of Jiangxi Province(20192BAB206017),the Science and Technology Research Project of Jiangxi Education Department(GJJ160643)and Jiangxi University of Science and Technology key disciplines to fund the project(33000004),the blasting vibration tests with different delay time are carried out on the similar model of concrete slope,and the vibration characteristics of each delay time are discussed with the MATLAB compiling program,and the optimum delay time of the model is selected from blasting vibration velocity,blasting vibration energy,blasting vibration frequency and structure response of response spectrum,at the same time,the attenuation effect of blasting seismic wave passing through different media structural plane is analyzed,and the ANSYS/LS-DYNA finite element simulation program is used to carry out numerical simulation analysis of delay time blasting vibration,and the following conclusions are obtained:(1)The blasting vibration tests with different delay time of t=0ms,t=5ms,t=6ms,t=7ms,t=8ms,t=9ms,t=10ms,t=15ms and t=25ms are carried out on the similar model of concrete slope.The vibration characteristics of each delay time of blasting are analyzed from the aspects of blasting vibration velocity,blasting vibration energy,blasting vibration frequency and structural response of response spectrum,the optimum delay time of the concrete slope similarity model is t=6ms through comprehensive evaluation of many indexes.(2)When the blasting seismic wave passed through the structural plane of different filled media,the smaller the wave impedance of the filled media,the smaller the peak vibration velocity and peak energy,and the stronger the high-frequency filtering effect,which shows that the energy distribution of blasting seismic wave among frequency bands becomes narrow,and the main frequency band tends to concentrate in the low frequency band of 0~30 Hz.(3)When water is used as the filled medium,both wave impedance and microcompression continuity of water affect the attenuation of blasting seismic wave,compared with other filled media,the continuity of water makes the peak vibration velocity and energy decay more slowly,and the energy distributes more widely in the frequency band,and the fluidity of water causes the main frequency band of blasting seismic wave to distribute differently in different propagation directions.(4)The numerical model of delay time blasting is established by ANSYS/LS-DYNA,the error of the simulation result of the peak vibration velocity is within 2.69%,which meets the characteristics of blasting vibration of rock slope,further more,the stress distribution,displacement variation and the range of plastic zone of slope under the action of blasting load are studied,the results show that there are stress concentration phenomena in the structural plane of the slope and the slope step,the slope bottom and edge of the slope step under the action of blasting load,which is easy to cause slope instability and destruction.