Experimental Studies On The Blasting Damage Accumulation And Vibration Propagation Regularity Of The Concrete

With the wide application of blasting technology,many concrete buildings(or structures)are likely to suffer from some continual blasting.Frequent blasting effect can cause damage accumulation of concrete,weaken the physical and mechanical properties and durability of concrete.When the damage accumulates to a certain degree,it may lead to partial or overall structure failure and seriously affect practicality,reliability and economy of the construction.The existing researches on damage law of concrete are mostly based on a single blast,rarely considering the damage accumulation effect.For these reasons,it is of great significance to carry out the experimental study on the blasting damage accumulation law of concrete and the propagation of blasting vibration based on damage accumulation.It is of great engineering value and theoretical significance to reveal the mechanism of the concrete dynamic instability and the control of blasting safety.Based on the analysis of literature,this paper had carried on the research work of the theory and the laboratory test.In theory,the paper summarized and analyzed the damage accumulation law of rock blasting,the damage law of concrete blasting and blasting vibration propagation law of concrete.In this article,the similarities and differences between macro and micro structure and physical and mechanical properties of the rock and the concrete had been discussed.Built on these,the paper explained the blast damage accumulation and fracture mechanism of the concrete and vibration propagation law.Based on the theoretical analyses,firstly,the blasting damage accumulation test of C40 and C60 concrete block was designed and carried out.In the experiment,the ultrasonic wave velocity of each test point was tested,and the cumulative damage value was calculated.The variation law of the cumulative damage of concrete blasting with the increase of distance and blasting action was analyzed.The relationship between cumulative damage and blasting circular time ratio,and the contrast distance was established.The cumulative evolution process and law of blasting damage in concrete were revealed.Then according to the blasting damage and blasting vibration test,the variation law of peak particle velocity and main vibration frequency with the increase of distance and blasting action was analyzed.And the regression analysis of the PPV and the main vibration frequency was carried out.Combined with damage accumulation analysis,the propagation and attenuation law of blasting vibration based on damage accumulation was revealed.Finally,the difference of damage accumulation process and fracture mechanism between C40 and C60 concrete was analyzed and compared.And the thesis analyzed the causes of vibration attenuation and concrete blasting cumulative damage changes with the distance and the time of blasting.After progressive research work,this dissertation drew some conclusions and made recommendations.To some extent,it can provide reference for the study on the performance of concrete under dynamic load of frequentative blasting.