被动方桩土拱效应三维有限元分析

基于大型有限元软件包ADINA,建立模拟被动方桩的三维有限元模型,对在桩顶边界条件和桩土接触变化时桩基的不同性状进行分析:包括土拱效应机理,桩土间的成拱效应,桩身挠度与表面荷载的变化规律以及桩侧土压力、桩身轴力的变化规律。分析结果表明,黏性土地基在邻近堆载作用下,桩身挠度与表面荷载呈非线性关系,可以用三折线模型来模拟;桩顶自由时,桩前土压力介于朗肯主动土压力与被动土压力间,呈非线性分布;在同种土中,桩侧极限土压力沿桩身呈线性分布,但比Ito理论和沈珠江理论都小。

3D FINITE ELEMENT RESEARCH ON SOIL ARCHING EFFECT BETWEEN THE PASSIVE SQUARE PILES

Based on the finite element program ADINA,a 3D finite element study considering the boundary condition and the contact condition is used to determine the pile-soil-pile interaction behaviour for closely spaced square passive pile rows.The mechanism of soil arching,the relation of the pile deflection and the surface load,the soil pressure of the side of pile and the axial force are studied.It is shown that the nonlinear relation between the pile deflection and the surface load can be modeled by three broken model. The earth pressure on the side of pile is smaller than the Rankine passive pressure and larger than the Rankine active pressure.The ultimate pressure on the piles in the same soil shows linear and smaller than that by the Ito theory and the Shen Zhujiang's theory.