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为了研究土表堆载分布形式对桩基负摩阻力作用的影响,设计实施了边载及围载作用下的单桩室内模型试验.桩周土采用细砂与饱和黏土,于加载过程中测定桩身应变、桩顶位移以及土体分层沉降.试验结果表明,土表堆载分布形式对桩基附加沉降具有较明显的影响,砂土中桩基在边载分级加载作用下的附加沉降约为围载时的77%,试验结束时黏土中桩基在边载作用下的附加沉降约为围载时的74%.边载作用下砂土及黏土中桩基中性点深度分别比围载时低约0.03L~0.08L和0.02L(L为有效桩长).在砂土承受土表堆载分级加载作用或者黏土排水固结的后期,因桩土相对位移不足以完全发挥负摩阻力作用,土表堆载分布形式对桩基负摩阻力影响减弱.
In order to study the effect of soil surface load distribution form on the negative friction resistance of pile foundation, the single-pile indoor model test under side load and surrounding load was designed and implemented.The fine soil and saturated clay were used in the soil around the pile, Pile body strain, pile top displacement and soil subsidence settlement.The experimental results show that the loading form of soil surface has a significant effect on the additional settlement of pile foundation, and the additional settlement of pile foundation in sand Which is about 77% of the time of surrounding loading, and the additional settlement of the pile foundation in the clay under the side loading is about 74% of the surrounding load at the end of the experiment. The depth of the neutral point of the pile foundation in sand and clay under the side loading is respectively About 0.03L ~ 0.08L and 0.02L (L is the effective pile length) at the time of loading.At the late stage when the sand soil is subjected to the staging loading effect of soil sheet or the consolidation of clay drainage, the relative displacement of pile soil is not enough to fully exert the negative The effect of frictional resistance and the influence of soil surface pile-loading distribution on the negative frictional resistance of pile foundation are weakened.