Computing of the Vertical Earth Pressure on High-Fill Culverts under Load Reduction Measures

In order to explore the stress state of high-fill culvert under load reduction, the expression of vertical earth pressure on slab culverts under load reduction condition was derived based on the conception of minor principal stress arch and combined with the Marston theory. Physical and mechanical properties of filling, culvert sizes, height of the fill have been considered in the formula. The results show: the vertical stress above the culvert structure is transferred to the soil outside the structure by soil arching effect under load reduction condition, which reduces culvert pressures. The influence range of soil arching effect on the stress in the external soil column is about 0.5 times of the structure width. Vertical earth pressure of structure is distributed evenly along the structure width direction. The soil arching effect is unconspicuous when the filling height on the top of tunnel is less than structure height. When the filling height on the top of tunnel is greater than structure height, the effect of load reduction measures is obvious. And the higher the filling height is, the more significant the load reduction effect is. The vertical earth pressure on culvert increased approximately linearly with the increment of fill height, but the growth rate is slowly. The formula shows certain accuracy and applicability by comparison with field measured values and numerical simulations.