Columnar jointed rock blasting fragmentation optimization based on changing inter-row delay time
The rock body of a tuff aggregate mine contains more developed columnar joints,which leads to a high rate of big block after blasting and increases the cost of secondary crushing.In order to reduce the rate of blasting big block in the mine,according to the field blasting production conditions and the characteristics of the development of rock joints,the numerical model of bench blasting of rock with columnar joints was established by using MATLAB and ANSYS/LS-DYNA.The numerical simulation test of columnar jointed rock bench blasting were carried out when the delay time between holes was 20 ms,which was same to the mine blasting,and the delay time between rows were set as 50 ms,46 ms,42 ms,37 ms and 33 ms respectively.The blasting fragmentation-damage criterion was obtained by comparative analysis blasting damage from the numerical model and fragmentation distribution from field blasting when the inter-hole delay time was 20 ms and inter-row delay time was 50 ms.The numerical simulation results under each working condition are analyzed statistically,and a conclusion can be drown that the best inter-row delay time for reducing the blasting big block rate was 42 ms when the inter-hole delay was 20 ms.Based on the numerical simulation results,the field blasting tests were carried out.The test results showed that when the inter-row delay was 42 ms and inter-hole delay was 20 ms,the blasting big block rate is 38.91％,which was 9.27 percentage points lower than the original blasting big block rate.
columnar jointed rockblock size optimizationLS-DYNAnumerical simulationinter-row delay time
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