宁波地区超长桩承载特性研究

Study on bearing chracteristics on superlong piles in Ningbo area

通过对宁波绕城高速公路东段软土地区26根超长桩静载测试数据的分析,研究了持力层为亚粘土、亚砂土的软土中超长桩的承载特性和荷载传递机理,得到了桩端阻力、桩侧摩阻力发挥规律和桩身压缩变形规律。结果表明,超长桩的Q-s曲线大多为缓变型;在极限状态下,端阻力一般占极限荷载的20%左右,桩身压缩量一般占桩顶总位移的30%～50%;同时得出了该地区粘土、淤泥质粘性土、亚粘土及亚砂土四种典型土层的荷载传递参数a、b的统计值,为今后超长桩的理论研究和设计应用提供了重要的参考。

Based on the static test results on 26 superlong piles under soft soil in East Ningbo Express Way,the bearing characteristics and load transfer mechanics are studied in the conditions where bearing strata are clay and sand respectively.The tip resistance,side resistance and compression displacement value are explored.The results show that Q-s curve varies gradually,tip resistance is about 20% of pile head load and the compression value is about 30% ～ 50% of pile head displacement.The statistic parameters（a,b） of load transfer are given for clay,silt clay,mild clay and mild sand,which will be a reference for research and design of superlong piles.