Field Experimental And Theoretical Study On Blating Wave Propagation Charcteristics Under Different Terrains

Based on the bed rock blasting excavation at Ling'ao Nuclear Power Station(LNPS),Guangdong,China,rock mass blast vibration has been monitored. By experiments on the spot and theoretic analyses,comprehensive studies are carried out on the law of propagation of vibration wave of blasting under different terrains. It is demonstrated that the attenuation law of vibration wave of blasting accord with expression of Sadaovsk Formula under even ground,whereas the topography affect greatly propagation of vibration wave under condition of variety of terrains. The concave landforms have great effects in decreasing scale of vibration wave of blasting. It is found that the attenuation coefficient of vibration wave in concave landform is not only relative to its width and depth,but also relative to charge weight per delay interval and explosive distance. The attenuation coefficient is diminished along with increase of explosive distance,but increased with charge weight per delay interval,width and depth of concave landforms. After having get through concave landforms,the primary frequency of vibration wave become small,but the time of vibration became longer than ever. And the protruding topography can enhance scale of vibration wave of blasting,its enhancement is relative to terrains height,charge weight per delay interval,explosive distance and scale distance of explosive. The amplified coefficient of vibration wave blasting is augmented with terrains height,charge weight per delay interval,and scale distance of explosive,but diminished with explosive distance. And the amplified coefficient of vibration wave blasting in intact rock mass is more than that in fragment rock.The reason that there is increase or decrease of vibration wave of blasting under different terrains is studied according to the wave propagation theory. It is stated that concave landforms can hold back propagation of surface wave. The attenuation of wave becomes more efficient when the wavelength of vibration wave of blasting is short. The protruding topography may have amplification effect on wave under condition of definite energy. The essential reason of these phenomena is that wave diffracts on the surface of protruding topography again and again.Based on properties of rock mass and parameters of explosive,the process of detonation in rock mass is simulated with LS-DYNA program,which adopts Von Mises failure criterion of geological material and the numerical results of explode loads on rock mass these agree well with the results of that corresponding experience formula.With the explode loads on rock mass,on the other hand,the effect of law of propagation of vibration wave of blasting under different terrains is simulated with the UDEC program. It is founded that the results of numerical simulation agree well with the spot experimental monitoring results. The numerical results show that,under protruding topography,the amplified coefficient of vibration wave blasting does not monotonously increase with the height of terrains. It is found that the amplified coefficient increase when the height of protruding topography is below a critical point ,but it will decrease if the height of protruding topography exceed the critical point. The change process of the amplified coefficient of vibration wave blasting with the height of terrains agrees well with the phenomena of theory analyzing wave propagation. The amplified coefficient is also relative to the ratio of height to width under condition of isolated protruding topography.It reason out a conclusion that a formula,which can show variety of protruding topography,established through dimensional analyses,with the experimental test and the theoretical analyses and the numerical simulation.