The Finite Element Analysis Of High-Speed Railway Standard Beam Bridge Pile And The Effective Length Explore

Because of Pile’s high capacity, good stability, small settlement and differential settlement, settlement stability, good seismic performance and good suitability to a variety of complex geological conditions, it is widely used in the construction of high-speed railway, highway and bridge engineering. Theoretical research can not catch up with engineering practice, even in the single pile under vertical load, the mechanism of interaction and load transfer characteristics have not yet been fully understood, leading to blind increasing design length of pile, directly into the pile bearing stratum layer in order to improve the safety factor. In response to this phenomenon, this paper established a large general-purpose software ADINA finite element model of the single pile, effective length factors of the bridge foundation pile as well as their law are deeply studied and analyzed, and calculation were compared with the cords. The main tasks are as follows:(1) Based on the handling method of contact problem in ADINA, the selection method of the time T and the friction coefficient are explored. In ADINA the critical relative displacement increment is used to control the tangential contact state. The tangential contact conditions are similar to the Goodman unit. Time T is no longer a dummy variable, but a contact-related variable, should be based on the experimental values. The specific method is: to create a finite element model to select the appropriate T value so that it coincides with the centrifuge model test results, and the actual soil interface friction can be simulated. The multi-layer soil friction coefficient is an average the internal friction angle acoording to the thickness.(2) Through the establishment of the single pile of finite element model, and based on the concept of effective pile length, the three methods of the effective length are determined. The core of these three methods is the pile settlement control or pile friction exertion cofficient control. Based on the method of calculation, the effective length of a bridge foundation is calculated and the influence of pile bearing load and pile-end soil modulus on the effective length is discussed. The results show that the effective length of the pile increases when the pile bearing load increases, decreases when the round soil modulus increases. Therefore, the effective length is based on the same load level. With different load level, the effective length will be different. Choosing a good soil as round soil can reduce the effective length. It should be considered in the design.(3) A high-speed railway standard beam single pile of pile finite element model is established. The transfer law of axial force, the pile settlement, relative displacement and pile friction coefficient is obtained. Based on the method for determining the effective length of the pile, that pile friction coefficient is less than or equal to15%, the effective length of the standard beam pile of high-speed rail is35m.(4) With the use of standardized methods, such as the code for design on round soil and foundation of railway bridge and culvert and technical code for building pile foundations, the settlement of a bridge pile is calculated, and compared with the finite element calculation results.