长短桩桩基础与其它类型基础的比较分析

Comparison and analysis between long-short-pile pile foundation and other types of foundations

采用三维弹塑性有限元方法对全短桩、全长桩、长短桩复合地基和长短桩桩基础进行了比较分析。筏板分析采用弹性薄板理论,土体采用莫尔-库仑弹性-理想塑性模型,桩体采用线弹性模型,桩土之间接触面采用非线性弹簧模拟。针对不同基础类型,从沉降性状和桩顶荷载大小以及长短桩的桩身轴力分布规律方面进行了比较分析。得出长短桩桩基础的平均沉降小于全短桩基础和长短桩复合地基,但仍大于全长桩基础。长短桩桩基础中长桩的中性点位置比长短桩复合地基的要深一些,受到的负摩阻力稍大些。长短桩桩基础中短桩作用发挥要比长短桩复合地基的短桩充分,而且其长桩的最大桩身轴力相比也小。

Three dimensional elastoplastic finite element method is adopted to analyze various types of foundations, which include short pile foundation, long pile foundation, long-short-pile composite foundation and long-short-pile pile foundation. Elastic thin plate theory is applied for research of raft, and Mohr-Coulomb elastoplastic model and linear elastic model for soil and piles respectively. Interface between pile and soil is simulated by nonlinear spring model. Comparative contents aim at settlement behavior and allocation of load at top of piles and axial force in long piles or short piles. The results showed that the average settlement of long-short-pile pile foundation is less than that of the whole short pile foundation and long-short-pile composite foundation, but larger than the whole long pile foundation. The neutral points of long piles lie deeper and suspend larger negative friction force in long-short-pile pile foundation than that in long-short-pile composite foundation. The role of short pile in long-short-pile pile foundation is more effective than that in long-short-pile composite foundation, but the maximum axial force of long piles is less than that in long-short-pile composite foundation.