Investigating the Behavior of RC Underground Structures Employing Ultra-high Strength Concrete under the Effects of Surface Blasts

Underground structures have entered into the passive defensce discussions as the secure structures in the past five decades. The resistance of tunnel concrete lining subjected to the loads generated by an external explosion is investigated in this study. For this purpose, investigation of tunnel lining subjected to blast waves has been performed using ABAQUS software. Effects of intensive impact loads caused by surface blast on the underground tunnel concrete lining with compressive strength of 30 MPa and also with ultra high strength concrete, both reinforced with steel fibers, with and without steel bars, have been studied. The comparison of the results based on the variation of elastic stresses and strains in tunnel lining has been performed. Explosion of explosive materials induce two types of shock and induction waves at the ground level, both considered simultaneously in this study. The results indicates that the addition of steel fibers to the regular and ultra high strength concrete, with and without steel bars, in comparison to regular reinforced concrete with compressive strength of 30 MPa, under similar loading conditions, can lead to increase in compressive strength of the lining when subjected to explosion.