WHEEL-LOAD-INDUCED EARTH PRESSURES ON BOX CULVERTS

A full-scale 8-ft by 8-ft reinforced-concrete box culvert was constructed and instrumented with earth pressure cells. Dead loads caused by backfill and up to 8 ft of cover were applied in 2-ft increments. Live loads were applied at each level of cover by a test vehicle loaded to represent the alternate interstate design load, consisting of two 24,000-lb axles spaced 4 ft apart. Measured live-load earth pressures on the top slab are compared to various theoretical solutions for concentrated and distributed wheel loads and to pressures predicted by a finite element model. Empirical equations are presented that for shallow covers more accurately model the measured data than do the analytical and numerical methods studied.