填土荷载对邻近桩排影响的有限元分析

3D FEM Analysis of the Rectangle Pile Rows Subjected to Lateral Soil Movement from Embankment Load

建立了填土荷载对邻近桩排作用的三维有限元模型,分析桩顶边界条件和桩-土接触变化时桩基的不同性状,探讨了桩-土间土拱效应,分析了桩身挠曲、桩侧土压力和桩身轴力同填土荷载之间的变化规律。结果表明,填土荷载作用下,桩身挠曲与填土荷载成非线性关系,可以用三折线模型来模拟;桩顶自由时,桩前的土压力介于朗肯主动土压力和被动土压力之间,呈非线性分布。同种土中,桩侧土压力沿桩身呈线性分布,但比Ito理论和沈珠江理论求得的极限土压力都小。桩-土间设置接触单元能更实际地模拟桩基负摩擦力。所得结论对研究被动桩桩-土相互作用以及桥台桩基的设计和施工提供参考。

Three dimensional finite element analyses considering the boundary condition of the pile top and contact conditions between the piles and soil were carried out to investigate the pile-soil-pile interaction behavior. The mechanism of soil arching, the relation of the pile deflection and the embankment load, the soil pressure on the side surface of piles and the axial force of piles were analyzed. The results reveal that, the nonlinear relation between the pile deflection and the embankment load exists and can be modelled by three broken model; the magnitude of soil pressure on the side surface of piles is between the Rankine active soil pressures and Rankine passive soil pressures; the terminal pressure on the piles in the same soil shows linear increase with depth and smaller than the ultimate soil pressures calculated with Ito theory and Shen Zhu-jiang＇ s theory; negative skin friction can be better simulated using contact element between piles and soils. The results obtained provide useful knowledge to study the response of the passive pile and good guide to design pile foundation supporting abutment and construction.