Study On The Design And Field Testof Integra Pile-Plank Overall Structurein Beijing-Shanghai High-Speed Railway

The foundation soil of low embankment may produce large plastic deformation and subsidence When it bears heavy dynamic loads, Especially when the foundation soil produces uneven subsidence, the influence on the face of embankment and track is far greater than that of high embankment because of the embankment's ability to adjust stress and resist deformation. The lower the embankment is, the smaller the capacity is and the greater impact of upper dynamic loads on foundation is. Using pile-plank overall structure to reinforce subgrade in deep soft soil area can effectively control the subgrade total and post-construction settlement. The pile-plank overall structure is characterized by simple structure, convenient construction and good economical along with technical performance, and it can satisfy the high requirement of the high-speed railway for high speed, stable, safe and comfortable. However, the structural types, mechanical characteristic, function mechanism and applied scope of pile-plank overall structure lack comprehensive research and the contact problems between pile-plank overall structure and subgrade are always a research hotspot in geotechnical field at home and abroad. Consequently, it is of great practical significance to investigate the design methods of pile-plank overall structure, including the mechanics characteristics, structure sizes, structure-soil interaction and post-construction settlement.Firstly, based on the testing section of low embankment of Beijing-shanghai high-speed railway in deep soft soil area, fully investigation of the domestic and foreign current state of theory and application of pile-plank overall structure are conducted, according to the design and calculation methods of pile-plank structure used in operated Zhengzhou-Xi an and Wuhan-Guangzhou passenger dedicated lines,the plane calculation methods applying to pile-plank overall structure of low embankment in deep soft soil area are put forward by adopting the Building Pile Foundation and Railway Gauge to calculate settlement.and the analysis of structure comparatively.The settlement calculation methods are presented, which are suitable for pile-plank overall'structure of low embankment of high speed railway in deep soft soil area. The technical problems about the interaction between pile-plank overall structure and foundation soil are disposed. Node spring is employed to solve the problem about pile-soil interaction and line spring is used to solve the problem about plank-beam-soil interaction. Also, the important parameters of pile-plank overall structure are used for influence are analyszed and the allowed stress method is adopted to reinforce the structure based on plane calculation results.Secondly, according to the testing of pile-plank overall structure, the results of the stress deformation characteristics and foundation settlement behavior of low embankment of pile-plank overall structure by systematic field tests are obtained. Comparison between measured results and theoretical calculation results shows that the actual stress and deformation characteristics of pile-plank overall structure are agreed with theoretical calculation results, which verify the feasibility of theoretical calculation methods. The post-construction settlement can be forecast by settlement test results. According to forecast results and evaluation standard, the pile-plank overall structure can effectively control the embankment post-construction settlement of high-speed railway.At last, the structure is optimized from three aspects, structure types, main sizes and foundation reinforcing measures. The optimal design scheme is obtained, which can be applied to low embankment in deep soft area.In short, the design methods, calculation theory, using properties and design optimization of pile-plank overall structure are analyzed and discussed, which can be provided references for later research and design.