| Coal is still the main primary energy consumption in China.The main excavating method of hard rock roadway in coal mine is drilling and blasting.The fundamental and effective way to realize safe and efficient blasting in hard rock roadway is to use safe and high-power explosive and optimize cutting parameters.In this paper,the experiment,numerical simulation and application of cutting blasting are studied from the characteristics of explosive and cutting way.A safe high power water gel explosive containing KCl and NH4Cl flame inhibitors have been developed for hard rock roadway excavation,and its performance has been tested and evaluated.The mathematical model for formulation design of safe and high power water gel explosive containing high efficiency flame inhibitor was established.Based on the existing formulation of Class 2 and Class 3 permissible water gel explosive,three kinds of high efficiency flame inhibitor NaCl,KCl and NH4Cl were selected to replace CaCO3 in Class 3 water gel explosive.The influence rules of three kinds of flame inhibitor on detonation heat,detonation capacity and detonation temperature were studied.NaCl and KCl have a great influence on the detonation capacity,while NH4Cl has a better inhibition on the detonation temperature and a little influence on the detonation capacity.On this basis,seven formulas of safe and high power water gel explosives were designed.By means of experimental study of combustible gas and explosive performance and power capacity of each formulation,the optimal formulation of safe and high power water gel explosive containing KCl and NH4Cl compound flame suppressant was determined.Through laboratory test and authoritative detection,the new safety high power water gel explosive performance meets the technical requirements of Class 2 water gel explosive,while combustible gas security meets that of Class 3 water gel explosive.The parameters of the JWL equations of three kinds of water gel explosives were fitted by using the numerical optimization program lstopt based on differential evolution method and y rate equation of state.ANSY/LS-DY-NA dynamic finite element software is adopted to establish the numerical model of single hole blasting in the same medium and loading conditions,the blasting crushing effect of the three kinds of explosives are simulated,by comparing the results,the safe high-power water gel explosive is better than the traditional calss 3 water gel explosive in the index of crushing circle and fissure circle,and close to the level of class 2 water gel explosive.The tested results also verified the rationality of the fitting parameters.A quasi-3d model of cylinder cut blasting is established.In the condition of existing empty hole,the explosive stress wave forms a reflected tensile wave around the empty hole,which is superimposed with the explosive stress wave.The rock will be stretched and fractured under the reflected unloading,and the groove cavity formed by blasting is approximately in a diamond shape.While if there is no empty hole,the convergence and superposition of the stress wave will cause the rock broken by pressure,consuming most of the explosive energy and forming an approximate "cross" cavity.By comprehensive comparison,with the existence of empty hole,the cavity formed is larger and the rock in the cut area is more thoroughly broken.A 3D model of parallel cutting with a empty hole in the center was build,the surrounding rock was destroyed by the compression of the explosive stress wave and the shearing action due to the stress wave propagation,at the same time,as a result of the existence of empty hole,causing the reflective tensile stress,a circul crack was formed in the rock between the boreholes under compression,shear and tensile damage.The field application experiment of safe the high-power explosive and cutting parameter optimization was carried out,and it showed,(1)The efficiency of borehole and the crushing effect can be improved by using the wedge cutting with a straight hole in the center and reasonable blasting parameters.(2)With the same test conditions and equivalent of material consumption,the blasting effect of the safe and high-power explosives is close to class 2 explosive,which indicates that the blasting power of the safe and high-power explosive is Close to that of Class 2.(3)The blasting effect of the safe and high-power explosives is better than that of Class 3 explosive,indicating that the blasting power of the safe and high-power explosive is stronger than that of Class 2 explosive.Figure 54 Table 36 Reference 125... |
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