上拔荷载作用下桩的颗粒流数值模拟

对桩进行了承受上拔荷载作用的数值模拟试验并与物理实物试验实测值作了对比。应用颗粒流理论及其PFC2D程序,模拟研究了承受上拔荷载作用的桩及桩周土的细观力学特征,桩的上拔位移和颗粒的分布和速度。随荷载增加土颗粒的受影响区由大到小,且影响区边界逐渐明显,颗粒排列发生变化,形成了锥体状的受影响区域。根据土颗粒的分布、速度和位移的分布和变化,确定土中滑裂面为锥体状;数值模拟了上拔荷载、桩上拔位移与时步的关系,并与宏观物理实物试验的实测结果作了对比分析;综合确定了桩的极限上拔承载力。桩承受荷载过程中土颗粒细观结构变化的颗粒流仿真,是关于土体的细观力学特征与宏观力学响应相关联的初步研究。

Numerical simulation of Particle Flow Code for pile under uplifting load

Piles under uplifting load were tested with numer ical s imulation method,and the results of numerical simulation tests were compared wit h results of actual pile t ests.Using PFC~(2D)(Particle Flow Code in 2 Dimensions), meso-mechanical characteristics of sand particles were simulated numerically ,and distribution and velocity of sand particles as well as uplifting displacements of pile were studied.It was found that with increase of uplifting load the sizes of affected zone of particle decr ease fro m large to small,the arrangements of particles were changed,the aff ected taper zone of particle was formed,and the correspondin g taper fractured surface can be determined.The relations between uplifting load ,disp lacement and time were simulated numerically and compared with the results of actual pile tests,and the ultimate uplifting bearing capacity was defined. The numerical sim ulation of particle flow for soi l around piles under uplifting load is just an initial study on meso-mechanical characteristics and macro-mechanic al response.