Optimum Design Of Solidified Subgrade For Flexible Base Asphalt Pavement

The stiffness of the subgrade has a significant effect on the road performance of the upper surface layer and the base layer of the structure for a flexible base asphalt pavement.Since the mechanical properties of the soil mainly depend on the interaction between the soil particles,the strength and stiffness of the soil body can be enhanced by adding the admixture to enhance the bond between the soil particles,which has application in engineering prospect.The soil curing agent produced by the Lu Ye company is a composite curing agent that uses a polymer copolymer as a binder and is mixed with an inorganic filler.It has certain compression and impermeability properties and can effectively treat various roadbed earth.In this paper,through research on the microscopic mechanism and mechanical properties of the clay stabilized by the curing agent,the design method of the flexible base asphalt pavement based on the cured soil is proposed to provide scientific basis for the engineering application of the curing agent.Firstly,the basic mechanical properties,mechanical properties and water stability of reinforced soil are analyzed by the strength test.It is shown that the best amount of solidified soil is 0.025% and the curing age is about 21 d,while the water stability of the solidified soil is improved to a certain extent after sufficient curing.After that,combined with the mechanical properties of the soil in the triaxial test,the dynamic resilient modulus was analyzed based on the repeated loading triaxial test,which takes into account the factors of the perspective of materials,environment and construction technology.It is found that the health age,compaction and water content play an important role in the rebound modulus.Then,the prediction model of the dynamic rebound modulus of the subgrade is determined for subsequent structural analysis and calculation,which is based on the constitutive model of the soil.In addtion,the reinforcement mechanism of solidified soil was analyzed by means of scanning electron microscopy,Fourier infrared spectroscopy,and X-ray diffraction.The results show that with the incorporation of the curing agent,ion exchange and gelation reactions occur in the soil,which changes the type of adsorption of ions on the soil surface and makes the soil structure more compact and stable to a certain extent.Meanwhile,it is found that the road fluid curing agent will not have a large impact on the environment,which is under the comparison with inorganic solidified soil.Finally,combined with the nonlinear constitutive model and ABAQUS numerical simulation,the optimized design of the stubgrade and the equivalent calculation of the composite rebound modulus of the roadbed are calculated based on the demand for bearing capacity.the overall maximum compressive strain of the subgrade is determined as the iterative index and perform inverse calculation to calculate the comprehensive equivalent rebound modulus of the subgrade.As solidified soil,the closer the reinforcement location is to the road surface,the more obvious the reinforcement effect is,which has a great impact on the maximum compressive strain of the subgrade.This surface change of the subgrade modulus will greatly reduce the overall compressive strain of the subgrade,which is of great significance for controlling the permanent deformation of the road.Manwhile,the structural design process containing solidified soil is proposed according to the design requirements of long-life pavements and the cost analysis of pavement materials.