Effect of Soil Fill on the Load Distribution Characteristics of RC Skew Box Culverts for Road Under Bridge Design

Abstract

AbstractBox culvert for road under bridge (RUB) design is widely used for providing overhead passages for trains and highways through the box culvert. The varying topsoil fill height may positively or negatively affect the structural integrity of box culverts. The height of backfill over the culvert can influence vertical earth pressure and internal structural forces. The current work aimed to investigate the effect of soil filling on the load distribution characteristics of RC skew box culvert for RUB design. The RUB structures considered in this work are associated with a complex set of loadings such as self-weight of the structure, superimposed dead loads (SIDL) from railway components and soil fill, lateral earth pressures, surcharge from dead and live loads, high- and low-intensity live loads from different dynamic effects such as axle movement, replacement of existing tracks, curved tracks, wind forces, and longitudinal forces. The height of soil fill above the top slab was varied from 0.5 to 10 m with increments of 0.5 m, and corresponding loading intensities were calculated. A detailed comparative study on the varying dispersion of live and dead loads through soil fill for different fill heights was also carried out. The results show that the live-load effect does diminish with increasing fill depth. At fill depths beyond about 6.5 m, the live-load pressures are less than 10% of the dead-load pressure, and beyond this fill height, live-load effects can be neglected. Moreover, the intensity of lateral earth pressure was observed significantly higher than that of vertical soil fill loads.KeywordsBox culvertRoad under bridge (RUB) designSkew box culvertsSoil fillEarth pressure