复合桩基重复加卸载过程中侧向约束桩变位规律试验研究

发布时间：2019-04-03 13:34

【摘要】：复合桩基上堆载可能引起侧向约束桩侧移,导致侧向约束桩和复合桩基失稳破坏。采用室内模型试验研究复合桩基重复加、卸载过程中侧向约束桩水平变位规律。结果表明:(1)复合桩基上加载时,侧向约束桩的桩身侧移沿深度先增大、后减小、存在峰值,峰值随加载增大而增大,出现在距离地面0.4倍地面以下桩长处,峰值位移与桩顶(或地面)处位移的比例系数和发生侧移的桩身长度随荷载增大而增大;(2)复合桩基上重复加、卸载时,侧向约束桩的桩顶侧移随桩间距增大而增大,弹性变形则变小。中桩侧移比边桩大。桩顶侧移增长率随重复加载次数增加而减小。若荷载超过首次加载的最大荷载,侧向复合地基上加载-桩水平位移曲线将回到首次加载曲线的延长线,具有记忆效应。第i?1次卸载曲线与第i次卸载曲线线型相似且相互平行。每次卸载的初、中期,荷载的减小不影响桩顶侧移,只有卸载到最后1~2级时,侧移才开始减小,直到永久塑性变形。侧向约束桩的顶部水平位移回弹曲线特征与岩石或土在垂直加、卸载作用下的回弹曲线相似。
[Abstract]:Pile loading on composite pile foundation may cause lateral restraint pile lateral displacement and instability failure of lateral constrained pile and composite pile foundation. The horizontal displacement rule of lateral constrained pile during repeated loading and unloading of composite pile foundation was studied by indoor model test. The results show that: (1) when the pile body is loaded on the composite pile foundation, the lateral displacement of the pile body increases at first, then decreases, and there is a peak value. The peak value increases with the loading, and appears below 0.4 times below the ground level. The ratio coefficient of the peak displacement to the displacement at the top of the pile (or ground) and the length of the pile with lateral displacement increase with the increase of the load. (2) when the pile is loaded repeatedly and unloaded, the lateral displacement of the pile top increases with the increase of pile spacing, while the elastic deformation decreases. The lateral displacement of the middle pile is larger than that of the side pile. The growth rate of pile top lateral movement decreases with the increase of repeated loading times. If the load exceeds the maximum load of the first load, the load-pile horizontal displacement curve on the lateral composite foundation will return to the extension line of the first loading curve, which has the memory effect. The first-order unloading curve is similar to the first-order unloading curve and is parallel to each other. At the beginning and middle of each unloading, the reduction of the load does not affect the lateral displacement of the pile top, but only when the load is unloaded to the last 1 ~ 2 order, the lateral displacement begins to decrease until the permanent plastic deformation. The characteristics of horizontal displacement springback curve of lateral confined pile are similar to those of rock or soil under vertical loading and unloading.
【作者单位】：长沙理工大学土木与建筑学院;长沙理工大学岩土工程施工灾变防控与环境修复技术协同创新中心;湖北省路桥集团有限公司;湖南省永龙高速公路建设开发有限公司;
【基金】：国家自然科学基金项目资助(No.51378083,No.50978036) 湖南省交通运输厅科技项目资助(No.201304) 国家级大学生创新实验项目资助(No.201410536003)
【分类号】：TU473.1

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