A Research On Differential Settlement Index Of High Filled Subgrade Based On Ride Comfort

With the rapid development of China's highway construction, the problems of the filled subgrade in mountains and hilly regions have become increasingly prominent. Meanwhile the uneven settlement of transition section not only influences the ride comfort and safe but also destroys the road surface quickly and heavily; but the studies on this question are few, especially in dynamics method. So, this paper analyses and discusses the differential settlement index based on ride comfort.Firstly, based on analysis of the subgrade settlement and deformation, in combination with engineering practice, this paper analyses the reasonable calculating position of the settlement on the cross-sectional, calculates the settlement value of the typical cross-section, which is belonged to the transition sections of high filleted subgrade, by layer-wise summation method; then discusses the form of the longitudinal-settlement-curve in transition section and calculates the settlement curve equation parameters of the different surface slopes, provides an analytical basis to research on settlement using vehicle dynamics .Than, this paper analyses the vehicle models and chooses the single-wheel model to study combinated the character of the question. Builds the vehicle oscillation equations according to Newton's Second Law, and solves the equations using Laplace transform and Laplace inverse transform, and makes program to calculate with Matlab. Chooses the parameters of the vehicle model and the model of settlement-curve, analyses the initial conditions of oscillation equations and the conditions of road surface displacement, actualizes the dynamic response analysis, and gives the examples, meanwhile analyses the influence of the parameters to the results.Finally, chooses the human weighed acceleration RMS as the index of ride comfort, and chooses the relative difference of max-longitudinal-slope as the differential settlement standard. Based on the given parameters, gains the relative differences of max-longitudinal-slope to different velocity, and brings forward the differential settlement standard of high filled subgrade.