| A dam is a water-retaining project built artificially to regulate and store floods.It can effectively transform and utilize hydraulic resources,regulate the irrigation and water conservancy of downstream farmland,and play an important role in my country’s economic development process.Concrete gravity dams are large-volume water-retaining structures constructed of concrete materials,relying on the self-weight of the dam group to generate strong stability to achieve the purpose of intercepting and retaining water.Because of its convenient materials and mature construction technology,it is widely used in rivers and reservoirs in my country.As an important strategic target,concrete gravity dams are the key targets of damage in local wars and terrorist attacks.The leakage of reservoir water caused by dam failure will seriously threaten the safety of people’s lives and properties downstream,and affect national security and political stability.It provides a theoretical basis for the research on the protection technology of concrete gravity dam under the action of weapon damage,and it is of great military significance to carry out research on the dynamic response and damage mechanism of concrete gravity dam under the action of water explosion.Aiming at the above problems,this paper carried out systematic model test and numerical simulation research,mainly including:1.Aiming at the problem of low accuracy of numerical simulation of the combined action of explosion shock wave and bubble pulsation in water,a free field model of water explosion shock wave propagation-bubble pulsation was established.Using the data of centrifuge test and prototype test,the reliability of the numerical calculation results such as explosion peak load,shock wave decay time,bubble pulsation period and radius change are verified.The application of similarity theory in scale model simulation is analyzed.The propagation law of explosive load in water is obtained,which lays a foundation for the calculation of water-structure dynamic interaction.2.Aiming at the fluid-solid coupling calculation problem of water body-structure dynamic interaction,the scale and prototype numerical models of water body-steel plate and water bodyconcrete gravity dam are established.The influence of atmospheric pressure,hydrostatic pressure,centrifugal acceleration,contact conditions and other factors are considered.The reliability of parameters and results is verified by using concrete implosion test and centrifuge test data.The dynamic action characteristics of shock wave and bubble pulsation load on the structure are obtained,which provides a basis for analyzing the damage evolution of the structure under the action of water explosion.3.In order to study the failure mode and damage mechanism of concrete gravity dam under the action of water explosion,a large scale water explosion model test was carried out.According to the actual dam structure characteristics,material characteristics,constraints and other factors,4 dam section groups and 3 independent water areas were designed,and 13 groups of water explosion tests under different working conditions were carried out.The results show that when the explosive equivalent is small and the blasting depth is shallow,the dam body produces local shear failure at the same height of the blasting core,forming transverse cracks penetrating to the downstream surface,resulting in the leakage of reservoir water.When the blasting depth is deep,the increase of the thickness of the dam body can effectively resist the local shear damage,and at the same time,the dam foundation is bent to produce transverse cracks,and the reservoir water seeps out from the cracks on the downstream surface.When the explosive equivalent is large,the dam body will be broken in a large area under the action of severe impact and shearing,the dam body will be fractured laterally,and the dam rupture will cause the reservoir water to gush out.4.In order to further analyze and verify the damage mechanism of concrete gravity dams,an integrated finite element model of explosives-water-structure-foundation was established.According to the obtained research results such as load characteristics and structural dynamic response,numerical simulation calculations are carried out for typical test conditions.The reliability of the numerical model and calculation results is verified.The damage evolution process of the dam structure is obtained,which provides a mature and reliable numerical simulation method for analyzing the dynamic response of concrete gravity dams. |
