Experimental And Numerical Simulation Study On Vibration Reduction Effect Of Blasting Barrier Holes

With the widespread application of blasting construction in underground engineering,the issue of blasting safety has attracted great attention from academia and engineering.Barrier holes can effectively control blasting vibration,which is a common vibration reduction measure in blasting engineering.However,at present,the arrangement of barrier holes in the project mostly depends on engineering experience.The understanding of the effect of barrier hole parameters on the vibration reduction effect is not systematic and thorough.And the improper layout of barrier holes often happen,as a result,the vibration reduction effect is poor or the construction cost is wasted.Therefore,revealing the influence rule of the geometric parameters of barrier holes on the vibration reduction effect and explore the action mechanism is of great significance for the optimal design of barrier hole geometric parameters in the process of blasting vibration control.The research results can provide a reference for the arrangement of barrier holes and disaster prevention and reduction in actual blasting projects.Aiming at the law of impact of barrier hole parameters(barrier hole diameter,barrier hole spacing and barrier hole row)on the vibration reduction effect,blasting model tests were designed and carried out.Under the action of underground opening blasting,the variation law of first-peak compressive strains of measuring points of the adjacent cavity,PPVs(particle peak velocity)on the surface of the test block and vibration-isolation rate at the measuring points before and after barrier hole screen under different barrier hole parameters is analyzed.The test results show that as hole diameter and hole row increase,or hole spacing decreases,the first-peak compressive strain of the adjacent chamber and PPV on the test block surface decrease,and the vibration-isolation rate increases,that is,the vibration reduction effect increases.The first-peak compressive strain of the measuring point on the left side wall of the adjacent chamber is greater than that on the upper side wall.And the difference between the two points decreases first and then increases with the increase of hole diameter,increases gradually with the increase of hole spacing and hole row.The PPV closer to the explosion source on the test block surface above the adjacent cavity is larger than that away from the explosion source.And the difference between the two points doesn’t change significantly with the increase of hole diameter,increases gradually with the increase of hole spacing,and decreases gradually with the increase of hole row.By comparing with the test results,the effectiveness and accuracy of the finite element program AUTODUN used to simulate the vibration reduction analysis of barrier holes under the explosion of underground cavity are verified.Through carrying out a large number of numerical simulations,the influence law of different hole diameter,hole spacing,distance between barrier hole and blasting source,and hole row on the vibration reduction effect is further explored,the change law of PPV and vibration-isolation rate at each measuring point is revealed.The numerical results show that as barrier hole diameter and hole row increase,or barrier hole spacing and the distance between barrier hole and blasting source decrease,PPVs on the adjacent chamber and ground decrease gradually,and vibration-isolation rates increase greatly.In addition,as barrier hole parameters change,the vibration-isolation rate of the measuring points before and after barrier holes and that of the measuring points before and after the rock mass between the holes show great differences: The former is significantly larger than the latter,and the difference between the two increases first and then decreases with the increase of hole diameter,and decreases rapidly with the increase of the distance between barrier hole and blasting source,and doesn’t change significantly with the increase of hole row.The change of barrier hole spacing affects the relative position of the measuring point and the barrier hole,thus determining the vibration-isolation rate of the measuring point.