Experimental Study Of Different Fiber RC Blast Walls Under Vapor Cloud Explosions

In recent years,frequent vapor cloud explosions(VCEs)have seriously threatened the harmony and stability of the society,causing great economic losses and leading damage to buildings.Blast wall can reduce the impact of explosive wave on building structures,which will protect building structures.It is of great practical significance and research value to explore the reinforcement scheme for improving the blast-resistant and protection performance of reinforced concrete blast wall under vapor cloud explosion.The main research work and innovations as following aspects:(1)The theories of vapor cloud explosion are summarized.Aiming at the current defects about the theory of vapor cloud explosion intensity,a new idea of vapor cloud explosion intensity research through damage criterion is proposed.The corresponding law of explosion wave is studied.The empirical calculation formulas corresponding to the overpressure peak,positive pressure action time and impulse are analyzed and compared.And the reasons for the differences in empirical formulas are explored.(2)The explosion experiment of different types of fiber reinforced concrete blast walls was designed and carried out.Based on the damage criterion,a damage analogy method which is more suitable for the study of the detonation intensity of vapor cloud explosions is proposed.According to the similar model,damage analogy method and orthogonal test method,the explosion experiments of six different types of blast walls were designed and fabricated.At the same time,the arrangement and mode of micro-measurement and macro-measurement of the fiber reinforced concrete blast wall were determined.And the test of the reinforced fiber concrete blast walls material was completed.(3)The measured data in the explosion experiment was analyzed by the wavelet transform.The results show that the propagation velocity of the explosion wave is affected by the blasting distance,the TNT dose and the longitudinal height of the measuring point.The overpressure peak,strain peak and acceleration peak corresponding to fiber reinforced concrete blast wall under vapor cloud explosions are unevenly distributed.During the explosion process,the peak strain of the steel bar is affected by the shock wave overpressure and impulse.The wall overpressure and the explosion wall acceleration are inversely related to the explosion proportional distance.And the fiber type and fiber volume affect the explosion shock wave and the explosion wall.Coupling effect has a slight effect on the overpressure of the explosion-proof wall surface.The overpressure peak is concavely curved at the longitudinal height,and the empirical formula of the proportional distance and the overpressure peak in the air explosion with obstacles is obtained.The incorporation of fiber can effectively improve the bending,impact resistance,deformation resistance and blast-resistant performance of reinforced concrete blast wall.The protective effect of BF,GF and SF in the explosion experiment is more and more significant.With the increase of fiber content,the blast-resistant performance of fiber reinforced concrete blast wall is better(4)The effect of fiber content on the blast-resistant performance of reinforced concrete blast wall was researched by numerical simulations.The three-dimensional finite element model of the separated reinforced concrete blast wall was established by software ANSYS/LS-DYNA.The ALE technique was selected as the simulation method of the explosion process in numerical analysis,and the constitutive model,strain rate effect,hourglass effect and structural failure of the material were considered.The random distribution of fibers in the reinforced concrete blast wall was carried out with the help of MATLAB.The results show that this method is reasonable and feasible,and the simulation results are in line with the actual situation.The model prediction results are in good agreement with the measured data,which indicates that the three-dimensional finite element model of the fiber reinforced concrete blast wall is effective.And blast-resistant performance of the reinforced fiber concrete under vapor cloud explosion could be predicted by this model.The effect of SF incorporation on the reinforced concrete blast wall is obvious.Research indicates that the degree of structural damage is reduced after incorporating SF.With the increase of SF content,the protective effect of SF on the reinforced concrete blast wall is more and more obvious.Combined with the disadvantages of the increase of SF content,it is considered that the blast-resistant performance of RC blast wall is best when the mixing content of SF is 5.0%.