静钻根植竹节桩抗压与抗拔承载特性分析  

Analysis of Bearing Characteristics of the Static Drill Rooted Nodular Piles Under Tension and Compression

作　　者：龚晓南[1,2] 解才 邵佳函 舒佳明 GONG Xiaonan;XIE Cai;SHAO Jiahan;SHU Jiaming(Research Center of Coastal and Urban Geotechnical Eng.,Zhejiang Univ.,Hangzhou 310058,China;Key Lab.of Soft Soils and Geoenvironmental Eng.,Ministry of Education,Zhejiang Univ.,Hangzhou 310058,China;ZCONE High-tech Pile Industry Holdings Company Limited,Ningbo 315000,China)

机构地区：[1]浙江大学滨海和城市岩土工程研究中心,浙江杭州310058 [2]浙江大学软弱土与环境土工教育部重点实验室,浙江杭州310058 [3]中淳高科桩业股份有限公司,浙江宁波315000

出　　处：《工程科学与技术》2018年第5期102-109,共8页Advanced Engineering Sciences

基　　金：国家自然科学基金资助项目(51278450)

摘　　要：静钻根植竹节桩是利用静钻根植工法将预制竹节管桩插入到水泥土中而形成的管桩-水泥土组合桩基。采用有限元软件ABAQUS建立现场抗压试桩与抗拔试桩的分析模型,计算得到的荷载-位移曲线与现场静载试验结果吻合,验证了模型的可靠性,采用数值计算方法,分析了竹节桩的抗压与抗拔承载特性。研究结果表明:软土地区,静钻根植竹节桩的抗压承载性能优于抗拔承载性能;桩身竹节可以使竹节桩与水泥土紧密结合,竹节不直接与土接触分担上部荷载;桩身非扩径段水泥土在荷载作用下只起到传递剪应力的作用,不分担上部荷载;桩顶位移60 mm时,管桩承担抗压桩总端阻的25.8%,承担抗拔桩总端阻的16.6%,均小于水泥土扩大头分担的端阻;竹节桩长度比R_N从0增大到0.375时,抗压桩极限承载力从3 045 kN增大到6 173 kN,抗拔桩极限承载力从1 910 kN增大到2 441 kN;竹节桩长度比从0增大到0.375时,抗压桩与抗拔桩桩端水泥土扩径段承担的荷载也明显增大;当竹节桩长度比从0.375增大到0.625时,静钻根植竹节桩的极限承载力、总侧摩阻力、管桩分担端阻和水泥土分担端阻改善效果不明显。The static drill rooted nodular pile is a kind of composite pile foundation by inserting the prefabricated nodular pile into the cemented soil.The FEM models of the PGPN(pre-bored grouting planted nodular)pile under compression and tension were established using ABAQUS,and the reliability of the model was verified by comparing the calculated load-displacement curves with the field test results.The axial bearing characteristics of the pile were analyzed by using numerical calculation method.The results show that the bearing characteristics of the PGPN pile under compression are better than that of pile under tension.The nodes along pile shaft can be closely combined with the surrounding cemented soil and that nodes do not bear the load from the soil directly.The cemented soil along the pile shaft only transfers the shear stress between pipe pile and soil.When S=60 mm,the pipe pile tip resistance accounts for 25.8%of the total pile tip resistance for pile under compression,and it accounts for 16.6%of the total pile tip resistance for pile under tension,which is less than the load borne by enlarged cemented soil pile base.When the nodular pile length ratio increases from 0 to 0.375,the ultimate bearing capacity of the pile under compression increases from 3 045 kN to 6 173 kN,and the ultimate bearing capacity of the pile under tension increases from 1 910 kN to 2 441 kN.At the same time,the enlarged pile base resistance increases significantly.However,when the length ratio is increased from 0.375 to 0.625,the ultimate bearing capacity,total pile shaft capacity,pipe pile tip resistance and enlarged pile base resistance are not improved obviously.

关 键 词：竹节桩 抗压桩 抗拔桩 承载特性 竹节桩长度比 

分 类 号：TU47[建筑科学—结构工程]