基于三维离散元法的强夯动力响应研究

为了从宏细观结合入手研究粗粒土在强夯作用下的动力响应机理,以干砂强夯室内模型试验为基础,通过引进和二次开发颗粒流程序(PFC3D),首次采用三维离散元法建立土体和重锤数值模型,模拟了强夯的动力冲击过程,研究了夯锤及土体的动力响应,并初步分析了土体颗粒运动规律.结果表明:强夯振动属于单峰值冲击振动,土体动应力峰值沿深度具有一定的滞后性,动应力的衰减在水平方向较竖直方向快,锤底土体颗粒以竖向运动为主,锤底斜下方颗粒主要做斜向下运动,锤侧颗粒以水平或斜向上运动为主,出现松动和飞起现象,数值模拟结果与室内模型试验基本吻合.研究工作为揭示强夯加固粗粒土细观机理及模拟实际工程问题提供了一种新的思路.

Discrete Element Modeling of Dynamic Compaction in Granular Soils Using PFC3D

This paper focused on the macro-meso mechanism of the dynamic response of dynamic compaction in granular soils based on its discrete nature. A three-dimensional discrete element model was first established to simulate the dynamic compaction process by means of secondary exploitation by using the particle code PFC3D and the numerical results were compared with the laboratory model tests. The validation of this numerical approach allowed the extended study of the dynamic response of the tamper and soils and the particles movement. The results show: 1) the dynamic stress propagates within a certain zone and there is a lag in the onset of the peak value along the depth;2) the dynamic stress attenuates more rapidly in the horizontal direction than in the vertical direction; and 3) the particles beneath the tamper mainly move vertically, while the particles below the tamper corners mainly move obliquely downward and the particles side of the tamper move horizontally or obliquely upward. The findings of this study provide a new route for the study of the meso-mechanism of granular soils improved by dynamic compaction.