Research On The Deformation Mechanism And Bearing Capacity Of No-buried Type Pile-plank Structure On High-speed Railway Subgrade

Currently, many new kinds of roadbed structures appeared in the process of theconstruction of high-speed rail and passenger line and pile-plank embankment as oneof a new structure has the advantages of good stability, high comfort, lessmaintenance，rigidity, good durability, economical and practical, and so on. Pile-plankembankment at home and abroad has been a certain degree use in routine engineeringpractice，but the relevant theoretical study is not perfect enough particularly in termsof the parameters selection of each part of pile-plank embankment and the stressmechanism and thus the above-mentioned problems are required to furtheraddress.Based on this, in order to provide technical basis for the design of pile plankstructure of high-speed railway subgrade，with the use of orthogonal experiment, theindoor model test and finite element numerical simulation，the optimization of designparameters and load-bearing characteristics of each part of non-embedded pile-plankstructure are systematically studied and settlement and mechanical properties of nobeam pile plate structure and a beam slab structure are compared in the static forcefield. Here are main ideas of this paper：（1）Firstly，the report reviews the common structure type of compositefoundation for high-speed rail，proposes the pile plate structure which belongs to anew composite foundation type and summarizes the application examples of pile platestructure at home and abroad，through reviewing the state-of-knowledge and thestate-of-the-art of the pile plate structure and concluding problems existing in thestudy，the main content and the basic line of the research are introduced in this paper.（2）Following the characteristics and classifications, design methods andprinciples, and other related theories of pile-plank embankment，two kinds ofnon-embedded pile-plank structures which are no beam pile plate structure and abeam slab structure are discussed in the paper.（3）From a technical point of view and economic indicators，several objectivefunctions and16set of orthogonal test plans are defined and the corresponding targetresults for each test with the method of orthogonal test are calculated. Comprehensivecomparisons of the main factors for each objective function are accomplished with theuse of range analysis. Through the analysis of the main factors，the optimized analysisof the parameters of each part of the structure now studied and the reasonable valueranges are obtained. （4）A set of parameter in the optimized parameter values interval is selected asa pile plate structure prototype. With the method of unit influence line loading, themost unfavorable structural position of three typical sections which are mid-spancross, side span across and the pile top location of pile plate structure are obtained andloading conditions are determined. Through the usage of the geometric similarmethod and indoor model test，qualitatively analyze the deformation mechanism of nobeam pile plate structure and a beam slab structure in the static force field for fourkinds of loading conditions and mechanical characteristics of pile, bedplate and joistof pile plate structure.（5）Basing the MIDAS/GTS software，three-dimensional numerical analysismodel is established，settlement deformation and mechanical properties of two kindsof pile plate structures are systematically studied and structure deformation, axialforce of pile，stress of joist and the distribution of soil pressure in plate subsoil arediscussed in this report. This term is as the reference for engineering practice ofpile-plank embankment.