Study On Deformation Characteristics And Improvement Measures Of Subgrade And Pavement In Two-side Widening Highway

As many of the early constructed highway can no longer meet the dramatic demand of transportation,road construction mission is still hard.In order to satisfy such a huge volume of traffic needs and promote the urban development,on the one hand,it is necessary to build new roads constantly to achieve traffic diversion and relieve the existing traffic pressure;on the other hand,it worth paying more attention to the expansion of old roads to enhance their capacity.In the situation where the main body of China’s road network has been basically perfected,simply increasing the road network not only consumes a lot of resources,but also has no obvious effect on traffic mitigation.In comparison,the expansion of the old roads can ease the traffic pressure and reduce the waste of resources to a great extent.Besides,the economic benefits are quite compelling.This paper uses Abaqus finite element analysis software to establish the relevant numerical model of subgrade and pavement for the expansion project,analyzes the deformation characteristics of the old and new subgrade of the expansion project and the mechanical response in the pavement structure,and studies the deformation characteristics,step excavation,and setting of the double-widened road.The vertical reinforcement and the horizontal reinforcement improve the deformation of the subgrade.At the same time,the effects of different splicing widths,load types,load positions,and other conditions on the mechanics of the pavement structure are discussed.In view of the common pavement damage and its causes in the expansion project,the treatment of steel wire mesh reinforcement is studied.Studies have shown that when both sides are widened,the deformation of the subgrade is consistent on both sides,which is conducive to the stability of the subgrade.And it is a preferred option in the expansion project.Step excavation is beneficial to the good connection of embankment junction and can control the differential settlement of the new and old subgrade to a greater degree.The step height-to-width ratio is preferably 1:1.25 to 1:1.5.The vertical reinforcement performance directly reduces the vertical differential settlement of the old and new subgrade,but has little effect on the horizontal displacement.It is usually arranged on the inner third of the basement of the new road after excavation of the old subgrade step.The stitching of new and old pavements significantly affects the stress distribution within the structure,and the stitching seams of the grass-roots level should be avoided in the position of the wheel tracks.Theoretically,the 50-cm stitching width is a reasonable splicing width,but in practical projects,waste is greater.From other aspects,further study of reasonable splicing methods or measures to relieve stress between layers.Steel mesh reinforcement can reduce the stress level of each structural layer to a large extent,laying a significant role in the base layer bottom,which its width can be 0.7m ~ 1.0m.Besides,too wide wire mesh to relieve the effect of stress is not obvious,and steel wire strength has little effect on the internal stress of the structure.