Study On New Coupled Anti-sliding Structure Based On Creep Characteristics Of High-speed Railway Subgrade

This paper is based on creeping subgrade of a high-speed railway.Firstly,based on the natural geographical conditions of the project,the mechanism of creep of subgrade is discussed by synthesizing field monitoring,laboratory test and numerical calculation results.Then,aiming at the safe,effective and rapid treatment of creep disease of high-speed railway subgrade,based on field survey data,combined with numerical calculation and model test results,the spatial characteristics of creep body and its spatial distribution characteristics of sliding force are analyzed,and the arch-string coupling anti-sliding structure is proposed for the first time.Secondly,the mechanical characteristics of the new structure are analyzed by model tests,and the optimal pile-laying method of the structure is determined.Based on the optimal pile-laying method,the formation mechanism of the coupling effect of the new structure is studied by means of numerical analysis,and the factors affecting the coupling effect of the structure and the corresponding influencing laws are discussed.Thirdly,based on the "rigid frame method" of group pile calculation,considering the influence of pile-soil effect on the mechanical characteristics of anti-sliding structure,a new theoretical calculation method of coupled antisliding structure is proposed.Finally,the new coupled anti-sliding structure is applied to the treatment of creeping subgrade,and the long-term settlement of Subgrade under train dynamic load is calculated.The results show that the deformation of subgrade strengthened by this structure meets the requirements of the code and achieves the expected reinforcement effect.(1)Based on the results of field investigation and monitoring,combined with laboratory experiments and numerical analysis methods,the perimeter of creep zone,creep direction,creep cause and deformation development stage of subgrade are analyzed,and the mechanism of creep of subgrade is discussed.(2)Using the model test method to deeply analyze the spatial shape of the creep body,and based on the site survey,combined with the numerical analysis results to determine the spatial characteristics of the creep body.According to the spatial characteristics of creeping body,a new type of coupling anti-sliding structure –“arch-string coupling anti-sliding structure” is proposed.(3)Model tests under four working conditions were carried out to test the deformation and mechanical properties of the new coupled anti-slide structure under different pile laying modes.The anti-slide performance of the structure under different working conditions was compared and analyzed,and the optimal pile laying mode was determined,i.e.,the "string" pile laying mode with eight anti-slide piles in the first row at the rear,and the top of each pile needed to be constructed.(4)The formation mechanism and morphological characteristics of the coupling effect of the new coupled anti-sliding structure are studied.The sensitivity of the structural coupling effect to the main influencing factors is analyzed according to the orthogonal experimental,and the variation rule of the ultimate bearing capacity and the structural share ratio with each influencing factor is discussed.(5)By adding "virtual pile" to regularize the new anti-sliding structure,considering the influence of soil in the coupling structure on the deformation and internal force of the structure,a theoretical calculation method suitable for the new type of coupling anti-sliding structure is proposed,and the accuracy of the theoretical calculations was tested by numerical analysis.(6)The new coupled anti-sliding structure is applied to the creep subgrade reinforcement project.The long-term settlement value of the reinforced subgrade is calculated by combining the dynamic numerical analysis and the long-term settlement theory,and the validity of the new anti-sliding structure is verified.