Research On Subgrade Of G4 Expressway Widing Optimized And Numerical Analysis Of Subgrade Construction Process

With the rapid development of economy in our country, The traffic flow of expressway increases day by day, The result is that original design capacity of expressway was already far the transportation demand which cannot satisfy grows, In order to adapt freeway development demand, More and more freeways faced with wideing. But the widing engineering from the design to the construction, Had not proposed that systemic standard of freeway widen design, Cannot solve with mentality and the design method of the newly construction freeway widen the question. In addition, Which has completed widen engeering also have some technical question, Transportation effect also waits for the time to test, Therefore, The research on wideing engineering design and construction of the freehway have the very vital practical significance.The design of the widing freeway will inevitably involve a series of questions, such as the differential settlement between new and old subgrade, foundation treatment problems, This article summarized the main way to broaden and analysis methods, using finite element program PLAXIS analysis of the embankment height and the lower part of the new foundation of different degree of consolidation of embankment widening the impact of stress and strain distribution, has obtained the corresponding deformation rule.on the basis, the simulation reproduces the course of construction between new and old subgrade settlement generation, analysis and calculation of the subgrade and foundation of the deformation characteristics of the site and at the same time convergence of new and old roadbed construction program has been optimized design, the three convergence programs the optimum selection programs. In addition, the widing engeering on soft ground different treatment measures in numerical simulation and suggest the measure of dealing with soft foundation by prestressed concrete pipe.Analysis showed that the consolidation degree of the foundation of old and new subgrade have big influence on the differential settlement between new and old subgrade;geogrid plaied a good coordinating role on the new and old subgrade's deformation and improved the overall stability of the embankment; prestressed concrete piles has played a good control effect of subsidence to soft ground.