Mechanism of stress characteristics on surface of slab-culverts under high embankments

The state and distribution of stress on the exterior surface of slab-culverts under high embankments are investigated through field monitoring and numerical simulation. The results show that the earth pressure on the top slab of culverts is larger than the self-weight of filling soils over it, and the pressure distribution is uneven. The earth pressure on the top of side wall of culverts is larger than that at the surface center of top slab because the side walls undertake the additional earth pressure caused by the neighboring filling soils. The measured lateral pressure on the side wall is much lower than the earth pressure at rest calculated from the height of filling soils, and the inhomogeneity of foundation leads to unequal lateral pressure on the sides of the culverts. The differential settlement between the culverts and the soils results in the additional earth pressure on the top slab which is larger than the weight of filling soils. The differential settlement of the culvert foundation causes the stress concentration to the top of one side wall of culverts and nonsymmetrical distribution of pressure on the side wall and base of culverts. The measured vertical earth pressure is about 1.56 to 3.02 times larger than the self-weight of the soils. Therefore, it is dangerous to use the existing highway standards to design slab culverts under high embankments.