Study On Site And Type Selections And Ground Bearing Capacity Of High Fill Culvert

At present, due to imperfect understanding of the designers to the soil-structure interaction of high fill culvert, the influencing factors of the landform and the ground conditions on the stresses of culvert, the embedding effect of the culvert foundation, and the modification of the ground bearing capacity are not considered sufficiently. As a result, higher ground bearing capacity is required. It is wasteful, as well as aggravates the vertical earth pressure concentration on the top of culverts, which brings about the potential structural hazard.According to these problems, the stresses and the displacements of high fill culvert are studied based on field test and FEM numerical simulation, as well as theoretical method in this thesis. The influence of the factors, such as the height of the fill, the boundary conditions of the culvert and the characteristics of the ground soil, etc., on the stresses and displacements of the soil-structure system, have been discussed in detail. Meanwhile, based on the complex orographic conditions, systematic researches on the culvert site and type selections are performed by theoretical analysis and numerical simulation. The variation laws of the stresses and displacements of the ground are analyzed and the influencing factors are discussed. In view of the embedding effect of the culvert foundation, the ground bearing capacity is modified and the scope of the ground treatment is determined. Furthermore, the comparative analyses on the different ground treatment methods are conducted in this thesis.The research results show that the boundary conditions, the characteristics of ground soil and the eccentric load effect should be considered comprehensively in the culvert site and type selections. The vertical earth pressure increases with the stiffness of the ground and the width of the trench, the differential settlement of the foundation increases with the eccentric load effect. The stiff stratum and non-uniform ground soil should be avoided immediately below the culvert foundation, and the influence of unsymmetrical trench installation on the stress of culvert should be considered. At the bottom level, the foundation pressure can be regarded as the roadbed pressure in the design, since the differential pressure is not obvious. The depth and width modification of the ground bearing capacity should be taken into account after improvement of the ground. The appropriate scope of treatment is about 3 times of the culvert width. The conclusions can provide valuable reference for site selection, type selection and foundation design of high fill culverts of expressway in mountain areas.