超长桩桩身压缩的试验与数值模拟研究

Tests and Numerical Simulation on Shaft Compression of Super-long Piles

基于试验资料和数值模拟，对超长桩的桩身压缩问题进行了研究。结果表明：（1）持力层对超长桩的桩身压缩有重要影响。入基岩的超长桩2（直径1m，长81．5m）的竖向变形一直以压缩变形为主（占84．50k-1000k）；未入基岩（以含砾中粗砂为持力层）的超长桩1（直径1m，长78．5m）的竖向变形以加载初期的压缩变形为主逐渐转变为加载后期的刚体变形为主（占75．3％）。（2）持力层上覆土性对桩身压缩也有影响。当其它条件相同而只有持力层上覆土层土性不同时，持力层上覆土层硬时桩身压缩量要大。（3）长径比对桩身压缩也有重要影响。一般情况是，相同的桩顶荷载时长径比越大，桩身压缩量也越大。

Based on the tests and numerical simulation, the shaft compression of super-long piles is studied and the following conclusions have been obtained. Firstly, the load-beating stratum has important influence to the shaft compression of the piles, the vertical deformation of the super-long pile 2 # （1m in diameter, 81.5m in length ） which penetrates into the load-bearing rock stratum is mainly the shaft compression （84.5% - 100%）, and the deformation of the super-long pile 1 # （lm in diameter, 78.5m in length） which doesn＇t penetrate into the stratum is mainly the rigid body displacement （about 75.3 % ）. Secondly, the properties of the strata over the bearing stratum also have the influence to the shaft compression. The harder the strata are, the larger the shaft compression is. Finally, the length-diameter ratio of the piles also has significant impact on the shaft compression. Under the same load on pile head, the higher the ratio is, the larger the shaft compression is.