| With the continuous advancement of urbanization in China and the acceleration of urban renewal,a large number of existing buildings need to be demolished.In urban intensive areas,traditional demolition methods often produce a large amount of dust,noise,toxic and harmful gas release,and have hidden dangers to the surrounding building environment.This paper presents a new technology for crushing concrete components by high voltage pulse discharge,which is safe,environmental friendly and efficient.Based on the high voltage pulse discharge technology,the crushing test of concrete beam is carried out.The main contents and conclusions are as follows:（1）Design and manufacture of 15 reinforced concrete beams,beam cross-section size of 250mm×450mm,beam span of 2400 mm,beam top and beam bottom are arranged 2 12 longitudinal reinforcements,stirrup using double limbφ8@200,hole diameter is divided into 40 mm and 50 mm two kinds,hole spacing is divided into 300 mm and 400 mm two kinds.Concrete strength grade is divided into C20,C30,C40 three kinds.The discharge voltage and the number of copper wires were taken as the changing parameters of the discharge test,and the discharge voltages were 40 k V,50 k V,60 k V,70 k V,80 k V,90 k V and 100 k V,and the number of copper wires was divided into 40,50 and 60,etc.（2）According to the test requirements,an impulse current generator is designed and manufactured,which is composed of three parts: supercharging,energy storage and discharge device.The charging power supply adopts 220V/10 A,the maximum charging voltage is 100 k V,the single release energy can reach 100 k J,can release2/20μs,4/10μs,8/20μs three current waveform.（3）15 reinforced concrete beams were crushed by high voltage pulse discharge.Firstly,through the comparative analysis of the crushing effect of the concrete beam by the two methods of the hydro-electric effect and the wire explosion,it can be found that the success rate of the wire explosion is 100% and the success rate of the hydro-electric effect is 80% in the process of 10 discharge tests.In addition,when other parameters are the same,the crushing effect of the wire explosion method is obviously better than that of the hydro-electric effect method,so the wire explosion is used as the high voltage pulse discharge method in this test.The effects of discharge voltage,concrete strength,number of copper wires,hole aperture and hole spacing on the crushing effect of high voltage pulse discharge concrete beams were investigated.（4）The experimental results show that the main crushing mode of concrete beam is forming longitudinal cracks along the side surface of the beam,and the concrete protective layer falls off and the steel skeleton is exposed.With the increase of discharge voltage and the number of copper wires,the crushing effect of concrete beam enhances greatly.With the decrease of concrete strength,the crushing effect of concrete beam increases slightly.When other parameters remain unchanged,the crushing effect of concrete beams with holes of 40 mm is better than that of concrete beams with holes of 50 mm.The crushing effect of concrete beams with 300 mm hole spacing is better than that of concrete beams with 400 mm hole spacing.（5）According to the test results,the mathematical expression between the failure degree of the concrete beam（the average crack width of the concrete beam side surface）and the discharge voltage,the number of copper wires,the concrete strength grade,the hole diameter and other key parameters is established.（6）In order to meet the needs of the project,the corresponding secondary crushing construction suggestions are put forward,and secondary crushing tests are carried out on 15 concrete beams.The results show that the concrete beams is broken into several pieces,which can meet the requirements of engineering demolition. |
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