Analysis On Antiknock Performance Of Concrete Gravity Dam

With the development of Hydropower Engineering technology, endless highdams and great reservoirs emerge, which brings about great economic and politicalbenefits and it is important to social development. Just due to their importance,undoubtedly dams become wartime targets and terror attack targets, which will bringgreat disaster and loss to the country, the consequences could be disastrous. In orderto study the damage mechanism and the possible failure modes, four main problemsin research on dynamic response and damage mechanism of dam under blast loadingare studied, in this dissertation. They are (1) antiknock performance of concretegravity dam subjected to different blast loads;(2) dynamic response and damage ofstructural under different underwater depth, the blast center distance and the bombdosage;(3) the influence of dam height, dam type, water level before dam on the blastresistance of the dam was analyzed;(4) analysis of Antiknock Resistance. Theprimary work and achievements are as follows:(1) Based on nonlinear finite element, strain rate effect of concrete dam wastaken into consideration in the establishment of gravity dam fully coupled model byusing software LS-DYNA. The possible failure mode and antiknock performance ofconcrete gravity dam was discussed, and this can provide references to the antiknockperformance-based assessment and protective design. The study shows that, damageeffects of dam is larger when subjected to underwater blast loading, and the dam ismost severely damaged when the bomb is attached on dam surface; penetrationexplosion and air explosion effects of damage to the dam mainly show local damageeffects, and penetration explosion presents as destruction feature of an explosive blasteffect, supplemented by a penetration effect.(2) In the condition of underwater blasting shock load, the response and failuremode of Dam were the key problems in evaluating the dam of antiknock safety.Numerical simulation method was used to study the dynamic response of the dambearing strong underwater explosion shock loading. It is found that the failure modesof dam under blast loading depend not only on its own dynamic characteristics, butalso on the underwater depth, the blast center distance and the bomb dosage; the headof a gravity dam is one of the weak parts for antiknock performance. A possible failure mode of a dam is that explosion to pits at upstream face concrete zones whichmeet explosive, explosion-induced collapse at crest and downstream, brittle punchingat joint of the head and upstream planes and near the downstream slope withpenetrating cracks.(3) In the condition of underwater blasting shock load, the dynamic response ofstructure under blast loading is much more complicated than that under other loadingssuch as static loading and earthquake loading. Taking the dynamic response andfailure mode of dam as evaluation criterion, the influence of dam height, water levelbefore dam on the blast resistance of the dam was analyzed, a theoretical basis wasprovided for Antiknock performance evaluation and protection design. Strain rateeffect of concrete dam was taken into consideration in the establishment of gravitydam fully coupled model. For this kind of concrete gravity dam, numerical resultsindicate that the blast resistance of low dam is weaker than that of high dam;numerical results also indicate that the water level before dam plays an important roleon antiknock performance of dam, and the antiknock performance of dam will beeffectively improved by reducing water level.(4) Dam will inevitably be destroyed because of strong underwater explosionshock loading. According to the dynamic response and failure mode, threealternatives of reinforcement are to be considered, the impact of local blast-resistantreinforcement was researched, the extent of cracks and the dynamic displacementresponse of dam crest were also given. The study shows that, dam is easy to have arebound phenomenon, The weakness part of antiknock is the head of dam, thecrushing damage, shock collapse damage and brittle punching failure are the mainfailure modes; reinforcement measures can limit antiknock expansion of crackssignificantly, reduce the extent of damage, and improve the antiknock performanceeffectively.