高原山区微型群桩基础承载特征及竖向-水平联合荷载研究
Load Bearing Characteristics of Micropile Group Foundation in Plateau Mountainous Area under Combined Vertical-Horizontal Loads
李海涛 1任光明 1冯川 1唐杨 2王霆 2王亮3
作者信息
- 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,成都 610059
- 2. 国家电网四川省电力公司,成都 610041
- 3. 国家电网阿坝供电公司,四川阿坝 624000
- 折叠
摘要
为探究高原山区微型群桩基础的承载特性以及水平、竖向荷载耦合作用(V-H联合荷载)的影响,揭示联合荷载相互作用规律,在高原山区微型群桩基础现场试验的基础上,采用FLAC3D对三种单一荷载情况进行数值反演,并对不同荷载比例下微型群桩基础的V-H联合加载进行模拟.结果表明:①抗压和抗水平试验中,承台效应明显,荷载-位移曲线为"缓变型";抗拔试验中,曲线为"陡变型".②联合荷载下,施加水平荷载会削弱桩基竖向承载能力,水平荷载比例较大时,桩身抵抗力矩和桩侧极限摩阻力增大,荷载-上拔位移曲线突变点消失;在竖向荷载的影响下,存在临界荷载比n,下压-水平联合荷载中n1=3.9,上拔-水平联合荷载中n2=0.76,荷载比＞n时,桩基水平承载力被削弱,＜n时,桩基水平承载力提高.③联合荷载下,水平承载力与荷载比的倒数呈四次函数关系,竖向承载力与荷载比的倒数呈二次函数关系;联合荷载下的屈服包络线与单向极限荷载垂线所围空间分为"破坏区"与"安全区",有别于单向加载的桩基承载特征,且桩基存在一个最优解,使各方向承载力均能得到充分发挥.
Abstract
The aim of this study is to investigate the bearing characteristics of micropile group foundations in plateau mountainous areas under coupled horizontal and vertical loads(combined V-H loads),and to uncover the law of interaction between these loads.On the basis of field tests,FLAC3D was employed to numerically analyze three sin-gle load cases(pure vertical compression,vertical uplift,and horizontal load),and to simulate combined V-H loads on micropile group foundations with various load ratios.Results reveal distinct behaviors:1)Compression and horizontal loading tests exhibit gradual variations,underscored by significant pile cap effects,whereas pullout tests demonstrate abrupt changes.2)Under combined V-H loads,horizontal loading reduces vertical bearing capacity.Higher horizontal load proportion yields larger pile resistance moment and ultimate friction resistance along pile side,eliminating abrupt changes in the curve of load versus uplift displacement.A critical ratio(n)of vertical load to horizontal load exists,equaling 3.9 under combined compression and horizontal loads and 0.76 under combined uplift and horizontal loads.Beyond these ratios,horizontal bearing capacity weakens or strengthens accordingly.3)Under combined V-H loads,horizontal bearing capacity varies as a quartic function of load ratio inverse,while ver-tical bearing capacity varies quadratically.The yield envelope and the unidirectional ultimate load perpendicular line enclose a space divided into"failure"and"safety"zones,distinct from unidirectional load conditions.Optimal solutions exist under load coupling,maximizing the bearing capacity of foundation in all directions.
关键词
微型群桩基础/V-H联合荷载/桩基承载性能/原型试验/数值模拟/高原山区/输变电工程Key words
micropile group foundation/joint vertical-horizontal loading/bearing capacity of pile foundation/pro-totype test/numerical simulation/plateau mountainous area/power transmission project引用本文复制引用
基金项目
国家电网公司科技项目(SGSCAB00JSJS1900683)
国家电网公司科技项目(SGSCDZ00JSJS2100272)
出版年
2024
国家科技期刊平台
NSTL
万方数据