Research On Cooperative Deformation And Integrated Design Method Of Foundation-Embankment-Subgrade

High-grade roads on soft soils often result in reduced pavement service performance or even structural damage due to uneven settlement of soft foundations.At present,the main research focuses on the treatment of soft soil foundations.The embankment and surface layer are still mostly constructed by traditional methods.Professionals of pavements,embankments and foundations perform their own duties and it lacks of a complete design system.The traditional road design method is still used in soft soil roads,and there are only some improvements being made.In order to study the transmission mechanism of uneven deformation in the road surface layer structure and soft soil-based diseases,the numerical simulation method is used to establish the mechanical model of foundation-embank-pavement.The deformation law under the height and the modulus of filling is proposed,different embankment filling embankments in different vehicle loads are analyzed.And a road integration design method based on the deformation synergy mechanism of the three combinations for the soft soil foundation is proposed.The research process is as follows:Firstly,considering the influence of embankment material parameters and structural forms on embankment deformation,different types of embankment-road interaction numerical models are established.The D-P model and the linear elastic model were selected as the material constitutive models of the earth-rock mixture embankment and the lightweight filler roadbed.For the three embankments of soli fill,soil-stone fill and rock fill,the settlement of the embankment under load is concentrated under the load of the central load of the road,and the diffusion to the surrounding is not obvious.For light fill embankments,the settlement of embankment under load is greater than that of the other three types of embankments.Under the condition of increasing the filling height of certain embankments,the variation of the settlement of three kinds of earth-rock mixture embankments is: rock fill>soil-stone fill> soil filling.Secondly,based on the established embankment-pavement numerical model,the deformation law of different embankment filling embankments under different vehicle loads,filling heights and packing modulus is analyzed.The research shows that the maximum settlement is proportional to the vehicle axle load and the embankment filling height;the settlement decreases with the increase of the modulus of the filling material,at the same time slowing rate is decreasing.On this basis,the soft soil foundation was introduced to establish the foundation-embankment-pavement integration model,and the variation law of settlement with construction stages,soft foundation modulus,vehicle load and rigid interlayer change was analyzed.It is found that the upward transfer of the settlement amount in the road structure will superimpose the compression deformation of the embankment and the thickness variation of the road structure layer,and it decreases with the height.The embankment and the surface layer are coordinated to adapt to the settlement of the foundation: under the action of load and self-weight,the pavement structure produces inter-layer coordinated deformation to fill the space created by the embankment consolidation settlement,but it appears to decrease as the structural layer becomes thicker and the soft foundation settlement increases upward.Then,based on the numerical model analysis,the sensitivity analysis of the factors that affecting the uneven settlement of soft foundation by orthogonal design test is used to obtain the main factors.It can be seen that the soft base modulus,vehicle load and embankment and surface layer weight are the four factors that contribute the most to the uneven settlement of the road surface.The degree of influence of the soft base modulus is about 6 times that of the surface layer,and the degree of influence of the vehicle load is about 4 times that of the surface layer.The contribution of the embankment gravity to the uneven settlement is basically the same as the surface layer weight.At the same time,the differential evolution algorithm is used to regress the predictive mechanics-empirical model of the uneven settlement of the road surface.Finally,based on the foundation-road embankment-road numerical analysis model and theoretical experience prediction model established,considering the threshold problem of road surface linear design caused by uneven roadbed deformation,combined with road design standards and functional requirements,uniform settlement,soft base modulus and embankment road weight are design control indicators,the road integrated planning system for poor geological roads considering the coordinated deformation of foundation,embankment and road surface is proposed.In summary,the research content of this paper can provide a theoretical method for the integrated design of pavement structure in road engineering in areas with unfavorable geology(such as soft soil quality).In order to improve the structural quality of soft soil foundation road engineering,and give a theoretical reference of improving the existing standards of foundation treatment,embankment design and pavement design.