大直径超长钻孔灌注桩承载性状

基于芝川河特大桥的桩基原位试验，对粉质砂土地区大直径超长钻孔灌注桩的承载力性状进行了分析，并将实测成果与现行《公路桥涵地基与基础设计规范》中经验公式的计算结果进行了对比分析。发现大直径超长钻孔灌注桩的承载力性状和中长桩或短桩的承载力性状具有明显差异；粉质砂土处于地面以下的不同部位，其侧阻力有较大差异；规范公式计算承载力结果明显小于原位试验结果，相差超过50％。研究结果表明，相同土质处于地面以下不同部位对桩产生的极限摩阻力不同，规范公式不适于评价大直径超长桩的承载力。

Bearing property of large-diameter over-length nonplacement pile

Based on the field test of pile foundation in Zhichuan river bridge, the bearing property of large-diameter over-length nonplacement pile in the area of powder sandy soil was studied, a comparison was made between the test result and the calculation value of empirical formula. It is pointed that there is a remarkable difference between the bearing property of large-diameter over-length nonplacement pile and that of medium length or short ones, when powder sandy soil is in different depth underground, its lateral resistance is different significantly, the bearing capacity difference of experimental piles and normalized formula is over 50%. The results show that the limiting lateral resistances of powder sandy soil of different depth are different, the normalized formula is not suited to evaluate the bearing capacity of large-diameter over-length nonplacement pile. 3 tabs, 4 figs, 9 refs.