Study On Differential Settlement Characteristics And Control Technology Of Subgrade In G320(Quzhou Section) Reconstruction And Expansion Project

With the "13th Five-Year" transportation development plan developing,the work that promoting the general national,provincial road quality improvement is put forward,widen the old road becomes a good solution to alleviate the traffic pressure and save the investment cost,pavement crack and subgrade instability and other bad patients caused by widening load will become increasingly exposed accordingly.The reason why new and old subgrade appear too large differential settlement is mainly due to improper design and construction.Combined with the Quzhou section in G320 national highway reconstruction project,stress and deformation of subgrade are analysed by using the numerical simulation method under different influence factors and treatment measures,mainly as follows:First,this paper summarizes the common diseases and the mechanism of the diseases about Highway Widening Engineering,and also analyzes the stress and deformation characteristics of the widened subgrade by using ABAQUS finite element software.Then,according to the construction plan and engineering practice of Quzhou section of G320 national highway expansion project,the influence made by road widening and width,different height and different subgrade embankment of soil physical and mechanical parameters,different strata combination,and shoulder wall interaction on the settlement and horizontal displacement of subgrade and foundation are explored through numerical analysis.Moreover,based on which,some corresponding suggestions put forward to control the unfavorable factors.Besides,the subgrade differential settlement deformation curve fitting functions are applied on the lower boundary of new and old pavement structure calculation model exspectively to simulate the mechanical response of new and old pavement structure to various the maximum differential settlement value of subgrade widening.On the basis of the pavement structure and function requirements,the control standard of four differential settlement levels is established with the variable slope rate as the control index.At last,through numerical calculation of treatment effect made by different sizes of excavation steps and geocell laying scheme,and the advices of the excavation step size selection,geocell laying scheme,subgrade filling and compaction,selection of foundation treatment plan are gave out from these four aspects.