非均匀地基中倾斜群桩竖向承载特性及群桩效应研究  

Study on Vertical Bearing Capacity and Pile Group Effect of Inclined Pile Foundation in Inhomogeneous Strata

作　　者：李龙起[1] 邓小雪 张帅[1] 何川 李昌林 LI Longqi;DENG Xiaoxue;ZHANG Shuai;HE Chuan;LI Changlin(State Key Lab.of Geohazard Prevention and Geoenvironment Protection,Chengdu Univ.of Technol.,Chengdu 610059,China)

机构地区：[1]成都理工大学地质灾害防治与地质环境保护国家重点实验室,四川成都610059

出　　处：《工程科学与技术》2020年第4期97-107,共11页Advanced Engineering Sciences

基　　金：国家自然科学基金项目(41502299)。

摘　　要：近年来,倾斜群桩被广泛应用于码头建设、桥梁基础等工程中抵抗横向荷载。随着研究的深入,其竖向承载特性也正引起学术界关注,如何评价倾斜群桩的竖向承载特性及群桩效应一直是工程中的难题。为此,结合厦门—深圳客运专线韩江特大桥桩基选型项目,就倾角为0°~12°周边倾斜的群桩基础分别建立5种桩间距分析模型,对其承载特性及群桩效应进行模拟试验和有限元分析。结果表明:就不同桩距的群桩基础竖向承载特性而言,群桩的最合理倾角为8°左右;竖直桩基的荷载–沉降曲线呈缓变型,倾斜桩基呈陡降型;沉降量在桩间距达到4d(d为室内模型试验基桩的直径)时骤然减小,且竖直桩基骤减值大于倾斜桩基;倾斜桩基地基土变形场的影响范围大于竖直桩基,随着荷载及桩间距的增大,桩间土竖向变形显著减小,桩间土夹持作用减弱,桩侧上部侧摩阻力在应力作用下逐渐增大;竖直群桩轴力为角桩>边桩>中桩,倾斜群桩轴力为中桩>角桩>边桩,轴力变化速率随桩间距的增大而增大;各基桩桩顶荷载分担随着群桩倾角及桩间距的增加趋于均匀;倾斜、竖直群桩群桩效应系数在桩间距为4d之前增长较快,在4d之后增长变缓慢;竖直桩基桩间距在5d时群桩效应系数达到稳定,倾斜桩基在6d时达到稳定,不同桩间距下均是倾角为8°时的倾斜桩基群桩效应系数最大。In recent years,inclined pile groups have been widely used in the construction of wharf and bridge foundation to resist lateral load,while its vertical bearing characteristics also attract the attention of researchers.How to evaluate the vertical bearing characteristics and pile effect of inclined pile groups is important in engineering.In this paper,combined with the pile foundation selection project of Hanjiang Bridge on Xiamen—Shenzhen passenger dedicated railway line,five kinds of pile spacing analysis models are established for the pile group foundation with inclination angle of 0°~12°,and the bearing characteristics and pile group effect are simulated and analyzed by finite element method.The results show that in terms of vertical bearing characteristics of pile foundation with different distance from group,the most reasonable inclination angle is about 8°.The load-settlement curve of vertical pile foundation is slow variant and the inclined pile foundation is steep variant.The settlement decreases suddenly when the pile spacing reaches 4 times of the diameter of the pile,and the sudden decrease value of vertical pile foundation is larger than that of inclined pile foundation.The influence range of soil deformation field of inclined pile base is larger than that of vertical pile foundation.With the increase of load and pile spacing,the vertical deformation of soil between piles decreases significantly,the clamping effect of soil between piles weakens,and the friction resistance of upper part of pile side increases gradually under the action of stress.The axial force of vertical pile group has the property of angular pile>side pile>middle pile,and the axial force of inclined pile group has medium pile>angle pile>side pile,whereas the change rate of axial force increases with the increase of pile spacing.The load sharing at the top of the pile tends to be uniform with the increase of the inclination angle and pile spacing of the pile group,and the effect coefficient of the vertical pile group increases r

关 键 词：倾斜群桩 竖向承载 群桩效应 数值模拟 模型试验 

分 类 号：TU473.1[建筑科学—结构工程]