Research On Deformation Behavior And Differential Settlement Limition Of Expressway Widening On Soft Soil Foundation

Due to the current increase of traffic, the capacity of the old expressways cannot meet the requirement. In terms of technical and economic analysises, the widening of the old expressways is a rational selection. Many expressways in the east-southern coastal region of China were built on the soft foundation. Because of the intrinsic complexity of soft soil, expressway-widening projects on soft foundation will be more complicated in this area. In general, the key technical problems of widening projects on soft soil foundation include the interaction of the old and new embankments, the treatment of the joint of the old and new embankments, the foundation treatment of the old and new soft foundation and differential settlement. The deformation behavior of embankment and differential settlement limitation of expressway widening on soft soil foundation are studied completely in this paper.Because the Biot's consolidations are complicated and cannot gain the calculation results directly, which are not convenient for projects, in terms of the Biot's consolidation theory, the solution of the initial excess pore water pressure and effective stress in the foundation under the embankment, as well as some brief formulas of the immediate settlement, the consolidation settlement and the total settlement are gained based on the characteristic of trapezoid loading acting on a strip area in this paper firstly. Then, it is found that the maximum additional stress and excess pore water pressure appear under the embankment widened. The settlement of foundation surface presents the shape of saddle, which is consistent with the field data.Then, due to the complexity of the constitutional equations of soft soil, loading history and boundary conditions, the theory solution cannot meet with the requirement of widening projects The behavior of the embankment widened is analyzed systemically using the computer code ABAQUS in this paper, including the additional stress field, displacement field and excess pore water pressure field in the foundation induced by the embankment widened, as well as the settlement of the old embankment surface during construction and the new and old embankments surface after construction. In addition, the effects of the width, the rigidity, the height of the embankment widened, the depth and rigidity of the foundation soil, the consolidation degree of the old road on the behavior of the embankment are explored.The selection of reinforcement is rational to guarantee a uniform of the old and new embankments of widening projects. In order to research the deformation behavior of reinforced embankment, the effects of the tensile stiffness, the position, the length embedded in the old embankment of geosynthetic and the stiffness of the soft foundation on the geosynthetic-reinforced embankment are studied combing with the centrifuge model tests of reinforced embankment on soft foundation. It is found that the field data and the calculation results are consistent with each other. Due to the new use of the composition foundation with piles to control settlement in...