Abstract
Increased traffic volume has made it necessary to increase highway capacities by widening embankments and pavements. Differential settlement of foundation consolidation and rational utilization of existing embankments are the main problems encountered in road reconstruction. In this paper, the finite difference method is used to simulate the construction process of using the existing embankments directly in the reconstruction project of expressway, and the fluid-solid coupling model of foundation settlement is established to calculate the differential settlement between foundation and subgrade. The influence of road widening mode and embankment height on differential settlement is analyzed. The mechanical response of subgrade under differential settlement is simulated and the law of uneven settlement of main reconstruction forms is investigated. The dynamic response of existing embankments soil under the action of rammer is systematically evaluated. The results show that, with the increase of consolidation time, the differential settlement is gradually obvious at the junction of the new and existing embankments, and there is a possibility of landslide along the junction of new embankments, which should be dealt with in engineering. The smaller the height difference between the existing foundation and the new foundation is, the more the position of the maximum settlement point of the foundation moves towards the new foundation. The greater the height of the new subgrade is, the greater the uneven settlement is. The criterion based on the single rammed energy and compaction stopping standard is proposed to determine the reinforcement depth of existing embankment.
Highlights
Widening of embankments has been increasingly adopted in practice to increase highway capacities due to demand for higher traffic volume than previously designed. e 1989 Government’s White Paper “Roads for Prosperity” [1] indicated that “about 60% of the motorway network in England as well as some truck roads will need to be widened by the provision of additional lanes.” Adding a new embankment adjacent to the existing embankment induces additional stresses and deformations under the widened portion and those under the existing embankment
Using the finite difference method, the numerical analysis results of the consolidation and settlement law of the ground caused by the transformation of grade road into expressway show the following: (1) In the process of road reconstruction, the size of foundation consolidation settlement is related to the widening mode and the height of the existing and new embankment
If the foundation and subgrade are not treated, the settlement of consolidation exceeds the requirements of the code, and the difference of settlement is more obvious at the junction of existing and new embankment. e settlement difference at the junction of existing and new embankment causes tensile damage on the surface of roadbed, which leads to longitudinal cracks and other diseases. e existence of the existing embankment makes the soil particles of the embankment move to the new foundation. e settlement difference of embankment after construction exceeds the bearing capacity of pavement structure, so engineering measures should be taken to reinforce the existing embankment and the new natural foundation and focus on the joint of the existing and new embankment
Summary
Widening of embankments has been increasingly adopted in practice to increase highway capacities due to demand for higher traffic volume than previously designed. e 1989 Government’s White Paper “Roads for Prosperity” [1] indicated that “about 60% of the motorway network in England as well as some truck roads will need to be widened by the provision of additional lanes.” Adding a new embankment adjacent to the existing embankment induces additional stresses and deformations under the widened portion and those under the existing embankment. By employing a large centrifugal tester and finite element program, Allersrma et al [7] and Vos et al [8] analyzed the stress distribution and deformation law of roadbed widening during construction by means of model test, numerical simulation, and field test. Zhou and Zhang [9] and Qian and Ling [10] used finite element calculation method to analyze the law of differential settlement of existing and new embankments in reconstruction and expansion project, studied the influence of different widening ways and widths on differential settlement, and explored the significant influence of differential settlement on the structural performance and service performance of existing roadbed and road surface. People’s research on this is relatively simple, so this paper will explore it
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