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FLAC 3D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n 1=3.9,上拔-水平联合荷载中n 2=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。
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,FLAC 3D was employed to numerically analyze three single 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 vertical 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.
作者
李海涛
任光明
冯川
唐杨
王霆
王亮
LI Hai-tao;REN Guang-ming;FENG Chuan;TANG Yang;WANG Ting;WANG Liang(State Key Laboratory of Geohazard Prevention and Geoenvironmental Protection,Chengdu University of Technology,Chengdu 610059,China;State Grid Sichuan Electric Power Company,Chengdu 610041,China;State Grid Aba Power Supply Company,Aba 624000,China)
出处
《长江科学院院报》
CSCD
北大核心
2024年第7期139-147,共9页
Journal of Changjiang River Scientific Research Institute
基金
国家电网公司科技项目(SGSCAB00JSJS1900683,SGSCDZ00JSJS2100272)。
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
micropile group foundation
joint vertical-horizontal loading
bearing capacity of pile foundation
prototype test
numerical simulation
plateau mountainous area
power transmission project
