Research On The Influence Of The Minimum Resistance Line And The Non-coupling Coefficient On The Explosion Energy Of Step Blasting

In order to study the influence of the minimum resistance line and uncoupling coefficient on the energy distribution law of step blasting,this paper based on the blasting theory and rock mechanics to derive the calculation method of rock breaking and crushing energy and throwing kinetic energy,poured concrete step model and used high-speed photography and vibration monitoring technology to carry out the blast test with the minimum resistance line and uncoupling coefficient as variables,analyzed the degree of rock fragmentation,the free-surface bulging process,the cavity shape,and the blasting vibration waveform.The research obtained the following results:?1?Calculation method of rock breaking energy,blast cavity?rock crushing energy?energy,throwing kinetic energy.A bench blasting explosion energy system is built with four parts as breaking energy,blast cavity energy consumption,throwing kinetic energy,and vibration energy as the core.?2?Within about 2ms after the explosive explodes,the explosive energy is mainly used for the generation of rock cracks,2-20ms,the explosive energy is mainly converted into the rock's new surface energy and throwing kinetic energy.After about 20ms,the broken rock is basically not affected by the explosive energy;Under the action of explosive gas,the free surface rock of the bench exhibits the characteristics of acceleration-constant speed-second acceleration-free throwing,and the initial throwing speed is reached after the second acceleration,the initial throwing speed of free surface particles show a normal distribution with the height of the step;The increase of the breaking energy density will increase the fractal dimension of the rock block,and the breaking effect is better.?3?The bench blasting test study of minimum resistance line W shows:The fractal dimension and breaking energy density are positively correlated with W,and K₅₀ is negatively correlated with W.The breaking energy meets the trend of increasing first and then decreasing as W increases.The utilization rate of breaking energy is between 4.97%-12.51%,it reaches the maximum when W is 180mm;Rock acceleration and initial throwing speed are positively correlated with W,and the throwing kinetic energy decreases with a negative power function as W increases,accounting for 8.45%-14.77%of the explosive energy;The increasing of W will delay the free surface bulge and prolong the compression and crushing time of the explosive products on the rock,resulting in an increase in the volume of the explosion chamber.And the energy consumption of the explosion chamber increases as a power function with the increase of W,accounting for 5%-21%of the explosive energy;Increasing W will extend the vibration duration and enhance the peak vibration speed of the particle,and the vibration energy increases as a exponential function with the increase of W,accounting for 0.15%-12.09%of the explosive energy.The proportion of the vibration energy occupied by the x direction is positively correlating with W;With the increase of W,the blasting effective energy ratio changes little,and the ineffective energy ratio gradually becomes larger.The optimal value range of W is 160mm-180mm.?4?The bench blasting test research of uncoupling coefficient K shows:The fractal dimension,breaking energy,breaking energy density,and breaking energy utilization rate showed a trend of increasing first and then decreasing as K increased,and reached the maximum when K was 1.5,and the K₅₀ shows a trend of decreasing first and then increasing,reaching the minimum when K is 1.5,the breaking energy accounts for 2.08%-3.62%of the explosive energy;Throwing kinetic energy decreases with a negative power function as K increases,accounting for 5.58%-15.26%of the explosive energy;Increasing K will reduce the degree of crushing of the rock and reduce the volume of the crushing rock.The energy of chamber expansion decreases with a negative exponential function as K increases,accounting for 2.95%-8.48%of the explosive energy;Increasing K will reduce the peak vibration speed in the x direction and reduce the vibration energy in the x and z directions,and when K increases to 1.5,the shock reduction capacity reaches the limit.The vibration energy decreases with a negative power function as K increases,accounting for 0.07%-1.57%of the explosive energy;The optimal value range of K is 1.5-2.0,at this range,the energy utilization rate is high,and the vibration hazard and rock crushing degree are small.Comparing the calculation results of the energy proportion of each part with the relevant literature,it is proved that the energy calculation method and the energy system are accurate and feasible,which can be used to calculate the energy of each part of the bench blasting.The research ideas and results of this article have important reference value and significance for improving the utilization efficiency of bench blasting energy,reducing rock crushing and blasting vibration hazards,and reasonably determining W and K of bench blasting.