Preliminary Study of Tensile Pile Behavior in Gravel Using PFC2D

• Main Authors: Wei-yang Ding, 丁偉洋
• Other Authors: Chine Chung Chiang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/10559764137623045397

碩士 === 國立雲林科技大學 === 營建工程系碩士班 === 101 === Because the rising water table may cause foundation to float, and affect the safety of structures, tensile piles often design to resist buoyancy. In order to understand the tensile pile behavior, this study was based on the foundation investigation and analysis report of a case in Taichung, and the discrete element program PFC2D (Particle Flow Code in 2 Dimensions) was used to simulate gravel formation and the tensile pile pullout tests. The particle bonding parameters were also calibrated with simulated tests and the formulas proposed by a number of scholars were used to examine results, and then analyses were performed to obtain the displacement of tensile pile and the change of interface between pile and gravels under various stages. Because the model contained a variety of gravel particle size, the gravel particles were generated with stratified rainstorm and random methods. During the pile pullout process, since the pile was not rigid, the parallel particle bonding was used to simulate pile deformation in PFC2D. Considering the reasonableness of gravel behavior, the results of pile tensile tests were compared with theoretical values for the next stage of simulation. In the pile pullout tests, due to the irregular bonding interface between cast-in-place piles and gravel layers, the rough interface was generated in numerical simulation. In addition, the particle parameters, kn and ks, were obtained by trial and error method to fit the ultimate pile pulling force, 520 tons, in the field pullout test. The analysis results showed that the particle size, arrangement and various particle parameters affected the tensile pile strength, especially the particle parameters had a great influence on the gravels moving during the pulling simulations. The ultimate pile pulling force of approximately 500 tons was obtained by the method proposed by the researchers, and compared with the gravel empirical formulas results of the β method and field test results. It was found that the deeper the smaller the β values of simulations were, and the trend was similar to the results of empirical formulas and field test. However, further studies of longer piles will be needed.