Study On Propagation Mechanism And Harm Control Of Blasting Shock Waves In Tunnel

With China’s industrial and agricultural production level increasing day by day, demand for transportation is growing.Highway and railway construction is developing by leaps and bounds.Especially with the development of the urban subway construction, a large number of city tunnels appear. The blasting shock wave and noise of tunnel construction will affect the surrounding residents’ personal safety and comfort.In order to alleviate the tunnel blasting shock wave impact on the environment and protect the safety of the surrounding residents, the thorough research must be conducted to the tunnel blasting shock wave.Then the appropriate control measures should be taked.Common research method of blasting shock wave has theoretical analysis, numerical simulation and experiment research. The numerical simulation calculation is the most widely used method. This paper summarizes the research situation, development trend and existing problems of highway tunnel blasting shock wave, expounds the basic principle of blasting shock wave formation and propagation, analyses the state of air in the tunnel. With CFD software FLUENT as the tool combining the reality construction of Shuangbei tunnel, a two-dimensional finite element model of double hole tunnel blasting shock wave is established. Using the established model systemically analyses the blasting shock wave propagation characteristics, the rule of overpressure distribution and the influence factor of overpressure attenuation. Using the deformation data examines the accuracy of simulation and theoretical research. Two kinds of overpressure control devices of the shock wave in the tunnel blasting construction are introduced. The main conclusions are as follows.1) Before the pressure field stability in the tunnel, shock wave overpressure distribution on the edge of the explosive filling area has one obvious dividing line. Internal pressure of explosive filling area is relatively small. Fill the outer area and the pressure is bigger. Mach reflection is gradually disappearing when the overpressure come to be stable. The shock wave front gradually developes into plane wave from the surface wave.2) The shock wave overpressure in tunnel tends to be stable when the distance is greater than 170 m. The overpressure is the largest without no cross passage at x=200m under the same initial condition, while is the least having reverse cross passage. Showing that the existence of the cross channel increases the attenuation rate of the blasting shock wave at some level. And the reverse cross passage effects more apparent.3) The simulation curve of blasting shock wave attenuation is consistent with the theory curve. The two curves can be regarded as basic coincidence when x＞15m. There are considerable differences of two curves when x<15m. The theoretical formula has a bigger error at this moment. The simulated value of overpressure near working face is more accurate.4) The shock wave overpressure in roadway is higher than that has no corner when the angle is 45°and 60°. The shock wave overpressure in roadway is lower than that has no corner when the angle is 90° and 135°. Shock wave overpressure is weaked the most viaing the angle of 90 when roadway has a corner. The shock wave overpressure attenuation amplitude increases with the increase of angle when 0＜θ＜90. The shock wave overpressure attenuation amplitude decreases with the increase of angle when 9O＜θ＜180.