The Vertical Earth Pressure On Culverts Under High Embankments

High fill culverts are widely applied in expressway in mountain area. There are many influencing factors on the vertical earth pressure on high fill culverts, and the variation law of the vertical earth pressure on the culvert is not accurately reflected by linear earth pressure theory in prevailing Chinese General Code for Design of Highway Bridges and Culverts. The results calculated by the method in the code are different from the field test results, which may induce various problems in the construction process or in service time of culverts, and influence on normal service of the expressway.According to this problem, the distribution and variation laws of nonlinear earth pressure on high fill culverts are studied based on the field test and FEM numerical simulation, as well as theoretical method in this thesis, and the influencing factors on the stress and displacement of the soil-structure system have been discussed in detail, such as the height of the fill, the boundary conditions of installation, the dimensions of the culvert, the characteristics of the fill, and the stiffness of the ground, etc. Several calculation methods of the vertical earth pressure are compared and their application scopes are indicated. Eventually, some common measures to reduce the earth pressure of high fill culverts are presented in the thesis.The research results show that the vertical earth pressure on the top of the embankment installation culvert or the imperfect trench installation culvert is greater than that calculated by the prevailing Chinese general code. The concentration factor nonlinearly increases with the height of the fill, and it approaches the peak value at a certain height of the fill, and then reduces slightly. There are many influencing factors on the vertical earth pressure on high fill culverts, most of which are related to the differential settlement of the fill on the top level of the culvert, and the larger the differential settlement is, the larger the concentration factor of the earth pressure is. The proper calculation method tally with the field conditions should be used in the design of culverts to avoid the economic waste and the structural hazard. When the fill is on a higher level, load-reducing measures could be adopted to reduce the vertical earth pressure, which improves the security of culverts.