基于离散元理论的静压沉桩过程颗粒流数值模拟

NUMERICAL SIMULATION OF PUNCHING PROCESSES BY PARTICLE FLOW CODE BASED ON DISCRETE ELEMENT METHOD

通过对二维颗粒流程序进行二次开发,对静压沉桩过程进行模拟。模拟结果揭示了桩端、桩周土体在桩土相互作用过程中各自所扮演的角色,从细观层面解释沉桩过程,将沉桩过程中桩体宏观力学行为表现与桩周土体受沉桩影响的细观结构变化联系起来,增进了对沉桩过程的深入理解和规律的揭示。主要结论如下:(1)不同桩端形式桩周颗粒位移表现不同;(2)端阻力随贯入过程均呈现似稳值现象;(3)桩–土宏观响应与土体细观参数变化之间存在紧密联系;(4)桩端接触面处颗粒以滚动为主,仅一小部分发生滑动;(5)端阻力与桩尖角度有一定联系。

The punching process is simulated by means of PFC2D and its re-development.In the simulation,piles with flat tip and tapered tip are adopted respectively.The effect of pile diameter is considered by adopting different diameters in the research of pile with flat tip.Tapered pile tips with different angles are researched as well.Results explain well the function of soil at pile tip and surrounding pile in the process of pile-soil interaction.In addition,the relationship between pile-soil macroscopical response and changes of soil mesomechanical parameters is intended to be established,which enhances the understand of punching process.Some valuable conclusions from numerical simulation are drawn as follows：（1） particles surrounding piles with different types of pile tip have different displacement behaviors;（2） pile end bearing capacities of flat pile tip and tapered pile tip will both tend towards a steady value while punching process continues;（3） pile-soil macroscopical response and changes of soil mesomechanical parameters do have close relation;（4） only a small fraction of particles locating at the contact surface of pile tip and particles have slippage relative to pile tip,while the others tumble on pile tip;and（5） pile end bearing capacity has some relations with angle of tapered pile tip.