Study On The Characteristics Of Air Shock Wave Propagation In Roadway Blasting Based On LS - DYNA Simulation

Blasting technology in the excavation underground space will produce numerous risk factors, which has a very high risk. Among them, the most concern is the mechanism characteristics as well as the prevention and control measures of the vibration, noise, flying rock, after damp and other risk factors, produced in the process of blasting, for the harm of blasting air shock wave is often neglected. However, because of the tunnel wall limit, the shock wave has been reflection and superposition phenomenon in the underground confined space operating process, so the duration of the shock wave becomes longer and the pressure decay gets slower, caused directly great damage to the personnel and equipment within the space. As a result, analyzing the blasting air shock wave propagation characteristics, and based on the relevant propagation to determine the safety area of personnel and equipment, at the same time, to develop the prevention and control measures, which not only can effectively reduce and control the damage caused by the shock wave, has certain guiding significance to engineering practice.In this paper, theoretical analysis, numerical simulation and field test are used to study the propagation characteristics of air shock wave in different tunnel. Firstly,the basic theory of air shock wave propagation is introduced,and the qualitative relations between the overpressure peak value、the amount of explosives, the equivalent section diameter and the distance are established under the support of the dimensional similarity theory.Secondly, using LS-DYNA software to simulate the model of the straight tunnel, the curve and the bifurcation tunnel. According to the simulation results of straight tunnel, with the aid of SPSS software, to determine the power function relationship between the peak overpressure and contrast distance, the contrast between the diameters,and to establish the specific dimensional model; And combined with empirical formula to calibrate the model,got the formula:ΔP=3.749·(?). Then,followed by the effects of different bend and bifurcation angle on the shock wave propagation characteristics, results show that:the angle of blend or fork is larger, the distance required by the shock wave recovery for plane wave is longer; The larger the deflection angle of the main roadway, the longer the distance to the plane wave. Finally, according to the situation of a tunnel blasting, combined with the dimensional model and field testing, the best escaping distance in the main roadway and the contacts is determined, and the measures to avoid the blasting are established.