The Study Of Vibration Isolation Mechanism And Effect Of Damping Hole In Blasting

Today, blasting have been used in more and more the actual project, especially in the densely populated, with a dense structure,in order to shorten the construction period. As a result, the influence of blasting vibration effect on the surrounding environment has become increasingly prominent. How to reduce the harmful influence of blasting vibration is increasingly attracting the attention of engineers. This paper takes Changsha subway line one automobile north station as engineering background. The isolation principle and isolation effect of damping holes were studied on theoretical analysis, numerical simulation and statistical analysis of monitoring data.(1) The isolation principle of damping hole was theoretically studied. Blasting seismic wave propagation is the process of interaction of the blasting seismic wave and propagation medium process and physical and mechanical properties of transmission medium produce very great effect of blasting seismic wave propagation. Damping hole in the transmission medium is equivalent to change the physical properties of propagation medium, the blasting seismic wave refraction, reflection, so as to reduce the blasting seismic wave energy. The interaction between the stress wave and incomplete consolidation medium were studied on the base of joint stiffness of interface description model. That is, the medium interface was see as a displacement of the interface of elastic half space. The resulting transmission coefficient is less than 1, showing the blasting seismic wave energy is lost when after damping hole.(2) With the use of Midas/GTS numerical simulation software, the damping hole has certain isolation (the damping rate of 10%～20%),and Damping hole on the number of Pai isolation effect is better, the more the smaller hole is apart from the isolation effect is better, 10 meters of the distance between explosion source and measuring point,,damping hole blasting vibration isolation effect is good, reaching 16% of damping ratio. With the distance increasing, the isolation effect decreases. The damping ratio is only 6% when the distance is 25 meters. The study shows that isolation effect reach the best when the distance between 10 to 25 meters.(3)Based on the least square, this paper uses the matlab software regression analysis for the blasting monitoring data. We noticed that vibration velocity with damping holes is less than those without damping holes(the shock absorption rate is between 10%-20%).And with the increase of critical pitch, shock absorption holes of the blasting vibration isolation effect is not obvious more and more, with damping hole fitting curve and without damping hole fitting curve is almost overlapped. Compared Midas/GTS numerical simulation data with field monitoring data contras, results of these two methods are close. This provide the basis for Midas/GTS numerical simulation software in the application of blasting vibration simulation.