Abstract: Culvert belong to buried construction, of which the stressing state is different from the buildings. With poor understanding on the mechanisms of the soil-culvert system and improper ground treatment of culvert, many geotechnical and pavement problems occurred for culverts during the construction process or under service conditions. In this study, field test and numerical simulation are conducted to investigate the mechanisms of soil-culvert system, the stressing state and deformation characteristics of which are obtained. Moreover, the ground treatment of culvert is also studied based on the fore-researches. Especially, the influence of ground treatment area and the ground stiffness of treatment area on the stressing state and deformation characteristics of soil-culvert system are analyzed by numerical simulation. This research reveals that vertical earth pressure is obviously concentrated on the crown of culvert; the influencing area is about 3b (b is the width of culvert) on the both sides of the culvert axes. The coefficient of earth pressure on the culvert crown increases with the height of fill, but it’s likely to approach a limit value at a higher fill. The vertical earth pressure on the culvert crown, the foundation pressure of culvert, as well as the internal forces of culvert decrease with increasing the ground treatment width and gradually tend to limit values; but they are nonlinearly increase with increasing the ground treatment depth and the ground stiffness of treatment area. It is suggestion that, in practical engineering, the ground treatment width should be about b+2h (h is height of culvert); the ground treatment depth and the ground stiffness of treatment area should be controlled by allowable settlement and/or differential settlement, but the ground treatment depth and the ground stiffness should not be increased extraneously.

Key words: culvert-soil system, stressing state, ground treatment, field test, numerical simulation