Numerical Investigation of the Effect of Shock Wave Caused by Air Explosion on the Nonlinear Behavior Downstream of the Arched Concrete Dam with Conwep Method

Due to the emergence of terrorist threats in recent years, in the form of air attacks, sudden explosions of ammunition and suicide bombers around special and strategically important structures such as arched concrete dams that have a very high capacity for storing surface water, the performance and design of this The threatened structures are mandatory and their possible failure can cause a huge flood, which can cause huge financial and human losses downstream. Therefore, the purpose of this research is to identify the nature of the explosion along with investigating the vulnerability of concrete dams. arching and investigating the parameters affecting the non-linear response of the structure by comparing the location change of the dam crest and the amount of compressive and tensile damage for dam-piling and dam-piling-reservoir systems due to explosion. The results of the sensitivity analysis for the linear and non-linear behavior of concrete showed that it is necessary to model the non-linear behavior of concrete in order to investigate the behavior of arched concrete dams against dynamic loads, especially loads of an impact nature such as explosion. In the linear mode, the changes in the amount of the explosive material in the time history of the location change are not noticeable and the permanent location change of the crown is very close to each other for all the explosive loading conditions and finally returns to the final value of the static condition. Also, comparing the outputs of linear and non-linear analysis showed that the difference between the answers from the explosion of 500 kg of TNT at a distance of 8 meters to 1500 kg of TNT at a distance of 2 meters has an increasing trend, so that the difference between the response of the change of location The background values for the linear and non-linear states are 18.7% and 25.2%, respectively, which emphasized the necessity of considering the non-linear behavior of concrete, especially for explosion in the near field. By comparing the maximum displacement responses of the full tank state, it was concluded that the presence of the tank reduces the influence of the reference point position and the amount of explosive charge on the crown response, compared to the empty tank state. Also, the results showed that in the full tank state The extent of pressure vulnerability is greater for the downstream, which indicates the application of hydrodynamic pressure of reservoir water to the downstream elements of the dam, and this happened due to the shape of the arch, but in the case of an empty reservoir, due to the absence of hydrodynamic pressure, the extent of this The damage was less.