桩身负摩阻力的现场测试与研究

某高速公路中桥桥台桩基础地层中有约１３ｍ厚的淤泥，在填土高４．５ｍ的情况下，对２根直径１．５ｍ，长２８ｍ的钢筋混凝土灌注桩进行了桩身应力，应变和桩周分层沉降的测试，测出中性点学术工和桩侧负摩阻力，通过实测值与设计预测值的比较，对各种计算和参数选取方法给以评价。

Study on the Field Measurement of Negative Friction of Piles

This paper deals with a field measurement study on the NF (negative friction) of piles. It was performed in a piled foundation of an abutment of a highway bridge. According to the geological investiga-tion, a muck layer exists in the strata with a thickness of 13m. The measurement was carried out for a couple of concrete cast-in-place piles, 1. 5m in diameter and 28m in length, which was covered with 4. 5m of filled soil on the pile top.The measured items include the shaft stress, strain and the settlement of surounding soil. Then, the depth of the neutral point and the NF of each pile could be obtained. At last, by comparing the designed val-ue with the measured one, several comments related to the calculating and the methods of parameter selection were discussed.