Finite Element Simulation Of Mechanical Response Of Pile-slab Structure Subgrade Over Sloped Weak Ground Under High Speed Train Moving Load

In the process of railway construction in the western region of China,the engineering problem of “sloped weak ground”(SWG)is frequently encountered.Compared with typical soft soil,SWG shows its different mechanical properties and it has a potential danger.In recent years,although the pile-slab structure composed of reinforced concrete has been successfully utilized to treat the embankment over SWG,the dynamic response law of this structure subjected to the moving load of high-speed trains is still not clear.The optimization of the design parameters of this structure is limited to several projects and research papers.Based on previous research work of embankment over SWG and pile-slab structure(PSS)at home and abroad,this paper mainly used the three-dimensional finite element method to study the dynamic response and service performance of the pile-slab structure of the sloped weak ground(PSS-SWG)subjected to the moving load of the high-speed train.The main work and conclusions of this paper are as follows:(1)Three methods of moving loads(subprogram development method,rigid body movement method and time series loading method),were successfully implemented in two finite element software(ABAQUS? and PLAXIS 3D?).The accuracy and applicability of the established numerical model were validated with an analytical solution.The respective characteristics of these methods were studied.The PLAXIS 3D software with the time series loading method was recommended as the research method in the following part.(2)A dynamic numerical model of the PSS-SWG was established.The difference of dynamic response between PSSSWG and PSS over horizontal weak soil foundation was investigated.What's more,the influence of train speed of PSS-SWG was discussed.(3)Several PLAXIS 3D models of PSS-SWG subjected to moving load was established.The influence of critical parameters,such as the properties of the pile,the depth of the platform,the pile diameter,the length of span,and the pile-slab connection was studied in the model.The countermeasures of design optimization of PSS-SWG was discussed.From dynamic perspective,this research will be helpful to the design theory of PSSSWG and this research has certain reference value to researchers who want to use finite element method to simulate subjected to surface moving load.