粗糙度对单桩竖向承载变形特性影响的试验研究  

Experimental study on the effect of roughness on the vertical bearing capacity and deformation characteristics of a single pile

作　　者：冷伍明[1,2] 丁荣锋 杨奇[1,2] 陈琛[1] 邓煜晨 徐方[1,3] 阮波 LENG Wu-ming;DING Rong-feng;YANG Qi;CHEN Chen;DENG Yu-chen;XU Fang;RUAN Bo(School of Civil Engineering,Central South University,Changsha,Hunan 410075,China;Key Laboratory of Engineering Structure of Heavy Railway,Ministry of Education,Central South University,Changsha,Hunan 410075,China;Hunan Tieyuan Civil Engineering Testing Co.,Ltd.,Changsha,Hunan 410075,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中南大学重载铁路工程结构教育部重点实验室,湖南长沙410075 [3]湖南铁院土木工程检测有限公司,湖南长沙410075

出　　处：《岩土力学》2024年第6期1597-1607,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51978672);上海局杭州铁路枢纽指挥部横向科研课题(No.2023-122);中国铁路设计集团有限公司(总-2022土建103);湖南铁院土木工程检测有限公司检测研究基金(No.HNTY2021K09)。

摘　　要：为探究桩侧粗糙度对单桩承载变形特性的影响规律,自主研发了多功能桩基静动力模型试验系统,构建了光滑、随机型及带肋规则型桩侧界面的模型单桩,通过3D形态扫描计算获得了桩侧表面粗糙度Rn,基于此开展了饱和砂土中单桩静载模型试验。试验结果表明:(1)粗糙度越大,单桩极限承载力和桩的割线刚度越大,桩顶沉降及其卸载回弹量越小,带肋桩能够有效提高桩基承载力并控制桩顶变形。(2)粗糙度越大,桩侧阻力越大,桩端附近侧阻力的强化效应越明显,桩侧阻力的分布模式随桩顶荷载增大由“单驼峰”到“锥顶柱”再至“斜坡”依次演变。(3)β值(β法中参数)随桩侧粗糙度的增大而增加,随深度增加而衰减。带肋桩的极限侧阻力及β值远大于砂纸和光滑桩,揭示了埋深和粗糙度对β值影响规律的机制。(4)桩侧粗糙度会影响砂土地基中桩端荷载传递函数类型,光滑桩、砂纸桩桩端荷载传递函数呈双曲线型,带肋桩呈直线型。上述研究结果对深刻认识桩侧粗糙度对单桩承载变形特性影响规律和机制具有重要参考价值。To investigate the influence of pile surface roughness on the bearing capacity and deformation characteristics of a single pile under vertical loading,a series of static loading tests was performed on a self-developed“multifunctional static and dynamic model test system for pile foundation”.Three single model piles with the smooth,random,and ribbed inerratic surface roughness were manufactured and their values of roughness(Rn)were obtained through 3D shape scanning calculation.The test results show that the ultimate bearing capacity and pile stiffness increase with augmenting of Rn,while the settlement of the pile top and its unloading rebound decrease with it.Specifically,the ribbed pile can effectively improve the pile’s bearing capacity and control the pile top’s vertical deformation.The pile side resistance and the strengthening effect of the side resistance near the pile tip also increase with increase in surface roughness.The distribution pattern of pile side resistance evolves from“single hump”to“cone top column”and finally to“slope type”with increased loads on pile top.The value ofβ(parameter inβmethod)increases with the increase in surface roughness and decreases with the increase in depth.The ultimate pile side resistance and the value ofβof the ribbed pile are far greater than that of smooth and sandpaper piles.These conclusions reveal influence mechanism of the buried depth and surface roughness on the value ofβ.Pile surface roughness affects the type of load transmission function of the pile tip in saturated sand.For smooth and sandpaper piles,the load transmission function of the pile tip follows a hyperbolic equation,whereas for ribbed piles,it follows a linear equation.These research findings are crucial for fully understanding the laws and mechanisms governing the influence of surface roughness on the bearing capacity and deformation characteristics of single piles.

关 键 词：桩侧粗糙度 模型试验 饱和砂土 桩侧阻力 桩端阻力 

分 类 号：TU473[建筑科学—结构工程]