砂土中开口管桩沉桩过程的颗粒流模拟研究  

Study of process of open-ended pipe pile driven into sand soil by particle flow simulation

作　　者：詹永祥[1] 姚海林[1] 董启朋[1] 贺东平[2] 

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,武汉430071 [2]中国水电顾问集团昆明勘测设计研究院勘察分院,昆明650041

出　　处：《岩土力学》2013年第1期283-289,共7页Rock and Soil Mechanics

基　　金：国家重点基础研究发展规划"973"项目(No.2013CB036405);交通运输部建设科技项目(No.2011 318 775 680);中国科学院重点部署项目(No.KZZD-EW-05)

摘　　要：基于颗粒流理论,采用PFC2D程序,模拟再现不同型号开口管桩在沉桩过程中土塞的形成演化规律、土颗粒细观结构变化以及桩周土应力场分布情况,并通过分析土体细观变化模式揭示沉桩过程中宏观力学响应的内在机制。计算结果表明,管桩直径对土塞效应影响很大,外径为30 mm的开口管桩,沉桩过程中土塞增量填充率(IFR)值较小,土塞效应明显,土塞高度小,类似闭口桩;随着管桩直径的增大,土塞效应迅速减小,大直径管桩在砂土中沉桩全部闭塞的可能性很小。细观因素(孔隙率和滑动比例)与土体宏观位移表现之间存在着明显的相互对应关系,并依此将桩周土划分3个区域。桩周土体水平应力、竖向应力和剪应力都在桩底附近形成"应力核",不同型号管桩桩周土应力场分布相近。Based on particle flow theory,the laws of soil plug formation,meso-structural changes of sand soil particles and stress field distributions of soil around pile are studied by using PFC2D to simulate and reconstruct the process for different types of open-ended pipe piles driven into sand soil.In addition,the macro-mechanical response is exposed by analyzing the variation of mesomechanical parameters.The results show that the soil plug effect is largely affected by the pipe diameter,for pipe pile of 30 mm outer diameter driven into sand soil,the value of the incremental filling ratio（IFR）is small,so the soil plug effect is significant and the height of soil plug is small,whose sinking mode is similar with close-ended pipe pile.While with the increase of pipe diameter,the plugging effect decreases rapidly,for the large diameter pipe,the sand soil in the pile is not plugged completely.The mesomechanical parameters such as porosity and sliding fraction have obvious corresponding relation with soil macro displacement;and based on this,soil around pile is divided into three regions.The horizontal stress,the vertical stress and the shear stress of soil around pile are formed the ＂stress nucleus＂ at pipe pile bottom during driving process,the stress field distributions of soil are close for different types of open-ended pipe piles.

关 键 词：砂土 开口管桩 土塞效应 颗粒流 细观 应力场 

分 类 号：TU473.1[建筑科学—结构工程]