Damage Mechanism And Its Effect Evaluation Method Of The High Arch Dam Subjected To Underwater Contact Explosions

With the development of dam technology in our country,a series of super-high arch dams with the height of 200～300 m have been constructed in southwest of China.These dams play an important role in flood control,power generation,sediment control and water resources control,and are important strategic resources of our country.However,due to its remarkable political and economic benefits,it will undoubtedly become the primary target in terrorist attacks and local conflicts.Moreover,with the development of guided bombs,intelligent torpedoes and UAV tactics,as well as increasingly frequent terrorist attacks and continuing tense regional relations,high arch dams are facing increasingly severe explosion-resistant environment.Once the high arch dam breaks due to the attacked by explosion,it will bring huge loss of life and property in downstream areas,and the social impact is unacceptable.Therefore,the study of the impact damage mechanism and its effect evaluation method of high arch dam under underwater contact explosion is carried out,the local damage mechanism and the overall spatial distribution characteristics of high arch dam under underwater contact explosion load are revealed,the damage effect evaluation method of local explosion on high arch dam is proposed,and the overall stability safety evaluation model of high arch dam under local explosion damage is established,which is an important content related to disaster prevention and anti-terrorism of major infrastructure in our country,and has important theoretical significance and engineering value.Aiming at the problem of impact damage mechanism and the effect evaluation method of high arch dam subjected to underwater contact explosion,this paper carries out relevant research by field test,theoretical analysis and numerical simulation.The main innovative work is as follows:(1)Damage characteristics of concrete slabs subjected to underwater/air contact explosions are investigated based on explosion testsBased on the field tests of concrete slabs subjected to underwater and air contact explosions,the effects of boundary support condition,explosive shape and reinforcement on the damage modes and damage characteristics of concrete slabs subjected to contact explosion loads are discussed.The damage modes and damage spatial distribution of concrete slabs subjected to underwater and air contact blasting loads are compared and analyzed.The damage mechanisms of concrete slabs under underwater and air contact explosions are revealed,which provide an experimental basis for the study of the transient fluid-structure interaction mechanism of multi-media under underwater contact explosion.(2)The transient fluid-structure interaction model of multi-media under underwater contact explosion is establishedThe CEL method,SPH method and FEM-SPH coupling method are used to establish the multi-medium transient fluid-structure interaction model of explosive-water-air-target structure,and the reliability of these models under contact explosion is verified by comparing with the results of field test.Based on the most effective fluid-structure coupling analysis method,the shock wave propagation in underwater contact explosion is studied.The dynamic interaction process between explosive shock wave,detonation products and interface is discussed.The mechanism of multi-medium transient coupling interaction between explosive load,water,air,and target structure under underwater contact explosion is revealed.(3)The damage mechanism of the high arch dam under underwater contact explosion is revealedBy establishing a fully coupled large-scale fine model of high arch dam-reservoir-foundation interaction system subjected to underwater contact explosion,the effects of upstream dam surface,free water surface in reservoir area,flood discharge holes in dam body and arch end face on the propagation characteristics of underwater explosion shock wave are discussed,and the dynamic interaction process between underwater contact explosion shock wave and dam surface is studied.The local damage process and spatial distribution characteristics of high arch dam under load acting on middle part of the dam,abutment,surface flood discharge holes and deep flood discharge holes are summarized.The typical damage mode of high arch dam under underwater contact explosion is generalized,and the influence of flood discharge holes on explosion resistance of the high arch dam is also discussed.(4)Evaluating methods for local damage effect of the high arch dam subjected to underwater contact explosion are proposedTaking the expansion depth of explosive damage along the thickness of dam body,the continuous cracking width of piers in flood discharge surface holes,the penetration damage degree of flood discharge deep holes and the shear damage area of arch end face as basic parameters,the criteria for determining the local explosive damage state of high arch dam in middle part of the dam,surface flood discharge holes,deep flood discharge holes and abutment are established.The evaluation methods of local damage effect of high arch dam subjected to underwater contact explosion are proposed.Based on linear regression analysis,taking the initiating explosive quantity of underwater contact explosion as basic variable,the damage assessment models of local explosion in middle part of dam,flood discharge holes and abutment of high arch dam subjected to underwater contact explosion are established.(5)Safety assessment methods for overall stability of the high arch dam with local explosion damaged are proposedBased on the systematic analysis of the influence of explosive damage in middle part of the dam on the stress distribution of undamaged upper dam body,the relationship between the expansion of explosive damage area in arch and the stress of undamaged upper dam body is deduced,and the safety evaluation method of overall stability of high arch dam un der partial explosive damage in middle part of the dam is put forward.Based on the spatial distribution characteristics of local explosive damage in abutment of high arch dam,the overall stability evaluation method of high arch dam with explosion damaged in abutment is proposed,and the possibility of overall instability of the high arch dam caused by local explosion damage of dam body or abutment are demonstrated.