An Investigation On Failure Mechanism Of Concrete-soil Double Layer Structure Subjected To Explosion

In the construction of national defence and national economy, undergroundexplosion can be seen in many fields such as earth penetrator explosion, undergroundarsenals design, mining and tunnel excavation. The process of underground explosionis the rapid release of the explosive’s energy. The blast wave and the expandingdetonation products instantaneously act on the surrounding substance, resulting inimpact and damage to the underground and surface structures. Therefore, the study ofdamage effect and fracture mechanism of underground explosion provides theoreticalreferences for national defense industry and national economy, having greatsignificance in scientific research and Engineering application. In this thesis, thebreakage and the dynamic destruction mechanism of double-layered medium underinternal blast load were studied in the method of numerical simulation andexperiment.First of all, the test scheme is designed for the concrete/soil double-layeredmedium based on the principle of blasting theory in brittle materials. Two cases withdifferent burying depth of the experiment are introduced. In the two cases, the damageresults of the double-layered medium are obtained. Through the analysis of the results,the roles of the stress wave and the explosion production in the damage of the targetare revealed.Based on the finite element software AUTODYN and the2D ALE algorithm, thenumerical simulation of the explosion process is conducted. The appropriate materialmodels are selected and the numerical simulation parameters are established after theanalysis of HJC and RHT models. By comparing the numerical and the experimentalresults, the reliability of simulation is proved, and the dynamic destructionmechanism of concrete under internal blast loading is interpreted.Finally, the influence of the thickness of concrete, the burying depth and theweight of the explosive are analyzed to the damage effects by more numericalsimulations. The results show that, the crush zone radius of concrete target isinversely proportional to the thickness of concrete and the buried depth, and isproportional to the weight of the explosive; The stress wave on the lower surface ofthe plate in the concrete is less affected by the thickness of concrete, and inversely proportional to the buried depth, inversely proportional to the weight of the explosive.