Research On Rock Blasting Basing On Annular Free Surface

As the rapid development of Chinese economic construction,more and more skyscrapers and traffic trails in the city were built.Thus,more advanced blasting technology was hoped and required during the infrastructure construction.In order to carry out blasting works in the city or near the city,the blasting program and methods often need to be discussed and evaluated by the experts with different background.Furthermore,the blasting process is usually restricted by various conditions.Traditional blasting method is very easy to affect the surrounding environment,under the action of blasting earthquake,the building will be affected by the role of vibration acceleration and resulted in inertial force,which may lead to structural and non-structural damage,and even secondary disasters.Therefore,many constructors refused to apply blasting construction.Despite the rapid development of machinery industry,drilling blasting construction is still one of the most important methods of mining tunnels,foundation pit blasting(especially under hard rock conditions).How to take good use of blasting technology,making it a tool to promote the development of human civilization,has become the goal of numerous blasting experts.In the recent years,the cost of artificial diamond has greatly reduced,which has brought a revolution to the drilling industry.On one hand,it greatly improved the performance of the drill.On the other hand,it reduced the diamond drill production costs.Thus,the core drill industry has developed well,making the annular free surface rock blasting method used in the engineering application possible.The process of the annular free surface rock blasting method is using a deep hole drilling rig,which is equipped with a core drill,to drill in the rock to the target position and then withdraw the core drill out of the rock and an annular free face is formed.After that,drilling a blast hole at the center of the core,and then blasting the core to complete the whole blasting process.This method can improve the efficiency of rock blasting,reduce the consumption of explosives,improve the utilization factor of explosive energy,reduce the blasting vibration and blast energy and play a very good protective effect on the surrounding environment.In this paper,a thorough study of the detonation mechanism,the effect and the vibration signal analysis of the annular free surface rock blasting method is carried out.Combined with the numerical simulation and experimental results,the specific research steps are as followed:Through the literature research,knowing the problems existing in the traditional blasting project and the influence of the free face on the blasting effect.It is concluded that the existence of free surface can improve the rock blasting efficiency,reduce the consumption of explosives and protect the surrounding environment effectively.Combined with the development status of the core drill,the numerical simulation and experiments of the annular free surface rock blasting are carried out.At the same time,the HHT transformation is used to analyze the blasting vibration signal measured in the experiment.It is concluded that the utilization factor of explosive energy can be improved,the blasting vibration and blasting energy can be reduced by the annular free surface rock blasting.