| Blasting technology is widely used in various engineering fields due to its high efficiency and economy.However,it has many negative effects,the most serious of which is vibration hazard.When the blasting vibration wave propagates through the rock to the building,it causes vibration of the building.When the vibration intensity exceeds the safety threshold,it will affect the building.In order to reduce the impact of blasting vibration,the vibration damping ditch is usually excavated between the explosion source and the protected building,and the parameters such as the size and position of the damping ditch have a direct influence on the vibration damping effect.The study of parameters such as the size and position of the vibration groove has important practical and theoretical value.Based on the A3 regional field blasting project of Lufeng Nuclear Power Plant Phase Ⅱ,this paper uses numerical simulation and indoor similarity model test to study the damping law and damping effect of damping ditch at different depths,widths and positions.The main research contents include the following aspects:1.Analyze the reflection and transmission mechanism of elastic seismic waves near the damping ditch.According to the analysis,the transmission and reflection of seismic waves passing through different media interfaces will cause energy dissipation.When considering only the incident and refraction of seismic waves,the damping ditch depth is the main influence parameter.When the size of the damping ditch is constant,then the vibration is reduced.The groove placement position is the main influence parameter.2.Based on the ANSYS/LS-DYNA program,the influence of the damping ditch parameters on the vibration propagation process is simulated,and the vibration data of the ground and the top of the lighthouse are obtained under different damping ditch.A similar model is made in combination with the site environment,and the vibration load is applied to collect the vibration data of the corresponding measuring point.3.Comparing the results of numerical simulation and similar model test,it is determined that the vibration velocity peaks of 1#and 2#measuring points are used to analyze the vibration reduction law and vibration damping effect of different depth,width and position damping ditch.The results show that for the top of the towered protected building(the top of the lighthouse),the damping ditch width is the main influence parameter;for low buildings(ground).the damping ditch depth is the main influence parameter;when the damping ditch position can be changed The closer the damping ditch is to the protected building,the better the damping effect.4.Calculate the regression coefficients of each model by using Sadov’s regression formula.It is found that the Sadovsky vibration prediction formula can not meet the requirements of actual engineering when the damping ditch exists,and fit the tower top under the condition of considering the damping ditch parameters.The vibration attenuation formula of the ground is verified by comparison experiments.The calculated values are basically consistent with the experimental values.It has certain reference value for actual engineering excavation and layout of damping ditch. |
