湛江组结构性黏土中开口桩土塞效应模型试验研究

在土层中打入开口桩，土体进入桩内形成土塞,土塞效应对桩的承载能力和沉桩后的工作性状有重要影响。在湛江组结构性黏土中打入开、闭口模型桩，进行了17组现场模型桩试验。通过对实验数据分析，得到了开、闭口桩的承载力以及土塞高度的变化情况与不同桩径、桩厚之间的关系；探讨了土塞增量与桩打入深度之比（IFR）随桩长与内径之比的变化规律，线性拟合出土塞增量与桩打入深度增量之比（IFR）与土塞高度与桩打入深度之比（PLR）的经验公式。结果表明：开口桩的承载力较同等规格的闭口桩承载力偏小，减小比例为20%-30%；土塞高度的增量随着桩径以及壁厚的增大而变大；随着管径的壁厚比越大，土塞相对高度越大；试验桩中土塞都是部分闭塞，但随着桩入土深度的继续增加，闭塞效果逐渐增强；IFR与PLR之比基本成线性关系。

Model experimental study on plugging effect of open pile in Zhanjiang Group structural clay

When breaking into the open pile in the soil layer, soil will into the pile and bring about the soil plug, The plugging effect on the bearing capacity of pile and working behavior after pile driving into the soil have important effects. 17 sets of open and closed model tests were carried out based on the special gray clay in zhanjiang area of China, studying the bearing capacity of the open pile and closed pile and the relationship between changes of soil height in different diameter and thickness of pile. Investigating the change rule between the incremental filling ratio(IFR) and ratio of length and diameter of pile.Linear fitting formula of the incremental filling ratio(IFR) and the plug length ratio(PLR). The experiment result shows that the bearing capacity of open pile is smaller about 20%-30% compared the equivalent standard close pile. The increment of soil height is bigger with the increase of pile diameter and wall thickness. the relative height of the plug is higher when the ratio of pile diameter and wall thickness increasing. The plug of modest pile are partial occlusion, occlusion effect is gradually enhanced with the increase of pile depth to soil. The ratio of IFR to PLR is basically linear.