چكيده به لاتين
The explosion is not only military-available and can have a variety of applications in civil fields. The adverse effects of the explosion, which can be caused by military activities or construction applications, should be taken into account. Studying the effects of explosion loads on underground structures and using methods to reduce these effects is important for safe design of these structures, especially from the perspective of passive defense. The present study aimed to numerically investigate the explosion and its effects reduction methods on underground structures using finite element method. ABAQUS software is used to model and mesh the geometry of the problem and the powerful LS-DYNA hydrocad solution is used for problem analysis. At first, the validation of the numerical model made using free field conditions and the relationships of regulations and centrifuge tests available in technical literature has been done in an unobstructed and impedimental state and after ensuring the correct operation of the model, the effective parameters in the problem have been investigated. In the present study, the combination of ALE and Lagrangian formulations and modeling of explosives on the soil surface have been used directly using the state equation. In this research, based on numerical model, the effect of parameters such as explosive weight, distance of explosives from underground structure, buried depth, thickness of structure wall, soil parameters, structure cross section shape, geofoam shape, geofoam angle, effect of using barrier with coarse grain soil and sheet pile, etc. The response of the underground structure has been investigated. The weight and distance of explosives from the structure are key parameters in the impact of the explosion on the underground structure. Also, the material of the environment and soil parameters will affect the response of the structure, so that increasing the adhesion and modulus of soil elasticity will increase the depreciation of the amount of energy reached to the structure. As a result, by recognizing these parameters, a safe margin can be created for the structure using appropriate materials or by increasing the thickness, hardness of the structure or deformation of the cross section, better performance can be created in the structure. The use of coarse-grained trenches as an inexpensive barrier can properly protect the explosion waves from reaching the structure compared to other obstacles. The use of geofoam with smooth surface has a greater impact on wave deviation and reduces the adverse effects of explosion and creates a slight angle for the barrier and improves its performance.
