Research On Safety Limit Of Deep-hole Bench Blasting Vibration In Anjialing Open-pit Mine

With the continuous advance of Anjialing blasting production face to the eastern border of mining area,the influence of blasting vibration on surrounding buildings can not be ignored.In this paper,the Safety limits of deep hole bench blasting vibration in Anjialing Open-pit Mine is studied.Firstly,Through consulting a large number of documents and analyzing the engineering geological conditions,design of deep hole bench blasting scheme and optimum delay Initiation network,determine the maximum detonation charge of a single section,analyze the direction of rock movement,and preliminarily predict the Safety limits of the building.Secondly,the blasting engineering is simulated by ANSYS/LS-DYNA.The variation of rock strain at different heights in the blasting zone is analyzed.It is concluded that the strain on one side of the free surface is large and the step has no backwash phenomenon.The attenuation law of blasting vibration velocity in the direction of X,Y,Z and closing velocity was obtained by non-linear regression analysis,and the correlation coefficient reached 0.93.The Safety limits of the industrial buildings and the civil buildings are predicted to be 251.92 m and 183.42 m,respectively.Then,through the blasting test of the optimal blasting scheme and the monitoring of blasting vibration,The frequency spectrum of vibration signals monitored on site is analyzed by FFT.It is concluded that the main frequency has no obvious attenuation law with the increase of detonation center distance.The main frequency of blasting vibration mainly concentrates in the range of 0 Hz to 30 Hz,which is close to the natural frequency of the surrounding buildings.It is easy to produce resonance and cause damage to the buildings.Nonlinear regression analysis of the measured peak blasting vibration velocity is carried out by using Sadowski's empirical formula.The attenuation laws of X,Y,Z and synthetic peak vibration velocity are obtained.According to the main frequency,the Safety limits of the civil buildings and the industrial buildings are predicted to be 200.77 m and 146.75 m respectively.The error of numerical simulation prediction and actual prediction is small,and the Safety limits of numerical simulation prediction is larger than that of actual prediction.The main reason is that there are joints and cracks in the rock,which leads to faster attenuation of blasting vibration speed.Last,based on the principle of reducing delay error of detonator and reducing single charge,the blasting scheme is optimized and analyzed by numerical simulation.the Safety limits of the civil buildings and the industrial buildings are predicted to be 142.33 m and 101.81 m,respectively.The results show that the optimization effect is remarkable and can be further promoted to the east side of Anjialing mining area boundary.The paper has 53 figures,24 tables and 66 references.