Assessment and Determination of Maximum Extra Pressure on Technical Buildings for Roads and Transportation Infrastructures near Topographic Irregularities under Blast Loads

Assessment of the effects of shockwaves caused by explosions near strategic structures such as roads, tunnels, bridges and railways has always been of high importance. The blast loads on structures are dependent on extra atmospheric pressure around the structures. Studies reveal that because of the natural properties of the waves, their behavior is affected by the geometry of the wave propagation domain. These considerations are not included in traditional methods of determining the forces due to blasts on structures. The technical buildings of railways and roads are mostly built in mountainous regions. If an explosion occurs around these structures, the blast waves will be scattered near topographic irregularities and the resulting extra pressure should be considered. Due to reflection of the blast waves near the topographic irregularities, it is not wise to apply common methods of determining forces resulting from explosions imposed on structures to evaluate bridges and embankments in the vicinity of topographic irregularities. The investigations reported in this paper show that this extra pressure imposed on technical structures of roads is much greater than that of flat regions. Furthermore, results demonstrated that with increasing the amount of explosives and decreasing the width-to-depth ratio of the valley, the extra pressure resulting from explosion and its reflection increases as well. Additionally, it was observed that even the applied pressure pattern near the topographic irregularities differs from that of flat regions.