Prediction Method And Control Technology Of Vibration Effect Of Deep-hole Bench Blasting In Open-pit Mine

As the main way of open-pit mining,blasting has obtained superior economic benefits for mining enterprises with the advantages of accurate,efficient and fast production.However,with the continuous development of our country’s economy,information technologyand people’s higher and higher requirements for environmental comfort,the discomfort caused by the collapse and vibration of construction structures prompt residents to complain.Furthermore,it leads to the delay of mine production period and the loss of mine economy,which is not conducive to the harmonious development of mining work.In order to control the harmful effects of blasting vibration effectively,relying on the school-enterprise cooperation project ‘Research and Development and Application of blasting Technology in complex Environment of Open-pit Mine’,this paper carries out field experiments in an open-pit mine of a quarry in Liling,Hunan Province.By using the research methods of theoretical analysis,field experiment,algorithm prediction and engineering verification,the parameters of the original blasting scheme are optimized to provide technical guidance for the blasting construction of open-pit mining.The main research contents and conclusions are as follows:(1)The rock physical and mechanical parameters,such as rock wave impedance and Platts coefficient,are obtained by indoor uniaxial compressive strength test,ultrasonic velocity test and point load test.Combined with the proposed rock blasting fragmentation classification table and the field blasting measurement effect,it is verified that the original blasting scheme explosive consumption of 0.45kg/m3 is the most suitable.(2)The field blasting experiment is carried out,and the data recorded by the blasting vibrometer Blast-UM are analyzed by the nonlinear regression method.The results show that the the site characteristics of the open-pit mine K and α are 149.73 and 1.29 respectively.The derived certificate repair formula is used to predict the blasting vibration velocity.Compared with the measured values,the relative error range of the blasting middle-near area(SD < 19)is between 40.06% and 46.33%,which means the prediction accuracy is low.(3)By using the grey correlation analysis method and combined with the on-site blasting vibration monitoring results,the factors affecting the blasting vibration velocity are analyzed.The influence order of various factors is as follows: blasting center distance > elevation difference > maximum section charge quantity > total charge quantity > maximum value time > hole depth >duration > hole distance > blockage length > minimum resistance line,among which the explosion center distance is the main influencing factor.Elevation difference,maximum section charge and maximum time are secondary factors.(4)Establishing the GRA-EPSO-LIBSVM prediction model,the main and secondary factors(blasting center distance,elevation difference,maximum charge quantity and maximum time)are taken as input parameters to train the GRA-EPSO-LIBSVM prediction model.Compared with the Sadolf formula model,the average relative error is 4.19% and 35.14% respectively.At this time,the best parameter is the penalty factor of 64.685 and the width coefficient of0.060.After the optimal parameters are determined,the maximum safe vibration velocity is selected,and the control value of the maximum charge deduced by the GRA-EPSO-LIBSVM model should not exceed 51 kg within 100 m and not more than 76 kg within 150 m.(5)On the basis of the original blasting scheme,the parameters are optimized,and the preliminary optimal design scheme is determined,and the field blasting experiment is carried out to verify it.The rock crushing quality and blasting vibration reduction effect of the preliminary optimization scheme are obtained through the test and analysis of fragmentation cumulative distribution curve and blasting vibration velocity.The best blasting scheme is recommended as follows: double-row hole interval uncoupled charge,delayed detonator detonator in-hole jump closed initiation network.The damping effect of the scheme is that the damping rate of the spaced decoupling charge can reach31.3% to 38.6% when the distance of the blasting center is between 80 to 150 meters,the damping rate of the damping ditch is about 40.8% to 51.4%,and the block rate of double-row holes is 65.14% lower than that of single-row holes.