抗拔桩循环承载特性数值模拟分析

Numerical analysis of the cyclic bearing behavior of the uplift piles

抗拔桩广泛应用于工业民用、桥梁、港口及近海工程.服役期间,抗拔桩不仅承受结构自重产生的静态荷载,同时承受竖向循环荷载.在循环荷载作用下,桩身上拔量是评判抗拔桩承载性能的重要指标.采用FLAC3D有限差分软件,模拟分析在竖向临界循环荷载水平较大时,抗拔桩的循环位移特性.研究表明,每次荷载循环中,抗拔桩上拔变形速度随荷载增加而逐渐加快;随循环次数的增加,桩身以及桩侧土体发生累积塑性变形,桩顶和桩端上拔位移逐渐增大,桩身回弹率则呈下降趋势;桩身长径比显著影响抗拔桩在循环荷载作用下的位移特性,长径比越小,桩身上拔量越大.

The uplift piles are widely used in industry and civil, bridges, ports as well as off-shore engineerings. During the service period the uplift piles bear static loading of weight and the vertical cyclic loading. Under cyclic loading, the pull-out amount of the uplift piles is one of the important indexes which judges its bearing capacity. This paper simulates the circulation displacement characteristics of the uplift piles by FLAC3D under large vertical critical cyclic loading. The study shows that the pull-out amount gradually accelerates the uplift piles with load increase in each loading cycle. With the increase of cycling number, the pull-out amount of pile top and toe, meanwhile, the rate of rebound decreases gradually, be-cause the plastic deformation of the pile and soil accumulates. Length-diameter ratio of the uplift piles significantly affects its circulation displacement characteristics under cyclic load-ing. The smaller the length-diameter ratio does the greater the pull-out amount of the uplift piles accelerates.