静压开口管桩沉桩过程模型试验及数值模拟  

MODEL TEST AND NUMERICAL SIMULATION OF DRIVING PROCESS OF OPEN-ENDED JACKED PIPE PILES

作　　者：周健[1,2] 陈小亮[1,2] 周凯敏[1,2] 王冠英 

机构地区：[1]同济大学岩土及地下工程教育部重点实验室,上海200092 [2]同济大学土木工程学院,上海200092 [3]青岛高新区投资开发有限公司,山东青岛266071

出　　处：《岩石力学与工程学报》2010年第A02期3839-3846,共8页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(50578122);高校博士点专项科研基金资助项目(200802470007)

摘　　要：利用侧面透明的模型箱和铝管半模桩模拟开口管桩在砂土中的沉桩过程。利用高分辨率数码摄录设备观察土塞形成的3个阶段,分析土塞形成的力学机制。在模型试验基础上,通过二次开发颗粒流程序PFC2D对沉桩全过程进行离散元数值模拟。结果表明,PFC2D能够模拟开口管桩从开始刺入砂土到形成土塞并最终呈现闭口管桩性态的整个过程;通过定性研究开口管桩在沉桩过程中土塞的形成演化规律、桩土接触面、土颗粒细观组构变化以及砂土颗粒运动规律等,从细观尺度出发探讨开口管桩沉桩过程中砂土的变形机制和土塞的形成机制。With the outstanding economic performance,open-ended jacked pipe piles have been widely used in engineering construction field,and plugging effects will be developed during the installation of open-end pipe piles,which have significant influence on the characteristics of pile while jacking into soil. The mechanism of soil plug formation and particles movement were analyzed by the meso-scale through physical model tests and numerical simulations. The container that consists of four steel sheets and one toughened glass side and aluminum semi-model pile were used to simulate the installation of open-end jacked pipe pile in sand. During the pile jacking into the sand,the courses of soil plug formation were observed from the transparent glass side and the processes can be divided into three stages,and the mechanisms of soil plug formation at three stages were revealed respectively. Based on the results of model test,the parameters of numerical model were determined by the biaxical test in PFC2D;and with the established numerical model and procedure in PFC2D,the driving process was simulated,which could consider both squeezing effects and plugging effects simultaneously. The behaviours of the numerical model are consistent with the results of physical model test. It indicates that PFC2D is capable of simulating the process for pile jacking into sand. In the research work,the courses of soil plug formation and displacement field of sand particles were analyzed. The particles within 5–7 times of particle diameters away from the ektexine of pipe pile will bring out large displacements and rotations,while beyond the thickness of 10–15 times of diameters,the particles will not be influenced almost. Furthermore,the analysis of porosity and contact numbers indicates that the bearing capacity of soil plug is mainly dependent on the lower part.

关 键 词：土力学 开口管桩 土塞效应 模型试验 数值模拟 颗粒流 细观 

分 类 号：TU41[建筑科学—岩土工程]