| In recent years,some high-speed railways built in the red bed area of Southwest China have the problem of continuous arch deformation during operation,which seriously affects the normal operation of the line.The existing research mainly attributed the reason of red bed subgrade arch to the water swelling of surrounding rock and the hydration reaction of filler,but the research on the reason of arch deformation from the rheological point of view is rare.Based on this,this paper takes a high-speed railway cutting section under construction in Southwest China as the background,from the perspective of rheological properties of red bed soft rock,uses the method of combining theoretical analysis and numerical simulation to analyze the causes of subgrade camber and deformation law.In view of this engineering problem,a new type of subgrade structure is proposed,which can not only control the arch deformation of the foundation,but also strengthen the slope.Then,the improvement effect of the new structure on the arch deformation of the subgrade is analyzed by theoretical and numerical simulation methods.The main results are as follows:(1)After excavation,the stress redistribution of the slope rock mass is carried out,and the horizontal stress of the slope base is much greater than the vertical stress.Combined with the strong rheological properties of the red bed soft rock,it is an important reason for the continuous arch of the base.Secondly,the interaction between the change of atmosphere,surface water and the mechanical properties of rock mass promotes the development of subgrade arch deformation.(2)A typical cutting section is selected and a three-dimensional numerical model is established.The M-C elastic-plastic model and cvisc viscoelastic plastic model are used to simulate the slope excavation process and the line operation stage.The results show that the vertical displacement of the base increases rapidly in the first three years of the operation stage,and after three years,the base continues to arch at a very small rate,and the deformation of the slope is no longer limited to the shallow rock,It is verified that the rheological property of red bed soft rock is one of the main reasons for continuous camber of subgrade.(3)Considering the rheological properties of red layer soft rock,the flatness of the cross and vertical section of subgrade will change,which will affect the normal operation of the line.The concrete performance is: during the train operation,the cross section will arch upward and the deformation will continue to increase with time;Secondly,because the height of the cutting slope along the line will change,a longitudinal slope will be generated on the longitudinal section of the subgrade.If the red layer soft rock slope is excavated,it will not take reinforcement measures to the subgrade,which will have an impact on the train operation.(4)Based on the structural mechanics and elastic foundation method,the stress analysis of the new pile plate structure proposed in this paper is carried out,and the practical engineering application of the structure is numerically simulated.The simulation results show that the structure can reduce the deformation rate of the subgrade arch to a certain extent,and the deformation of the subgrade in the cross section and vertical section is effectively controlled after the long-term operation of the line.(5)By changing the geometric parameters of the new subgrade structure in the numerical model,the influence of each part of the structure on the time-dependent deformation of the base is analyzed: increasing the thickness of the bearing plate,the ratio of span loss of the bearing plate,the length and diameter of the pile can improve the effect of the subgrade structure on the arch deformation of the subgrade,and enhance the flatness of the cross-section and vertical section of the subgrade;Although the reinforcement effect is limited by increasing the size of pressure relief hole,it can improve the flatness of subgrade surface. |
PDF Full Text Request