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 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.
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 /
prototype test /
numerical simulation /
plateau mountainous area /
power transmission project
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参考文献
[1] 程永锋,邵晓岩,朱全军.我国输电线路基础工程现状及存在的问题[J].电力建设,2002,23(3):32-34.(CHENG Yong-feng, SHAO Xiao-yan, ZHU Quan-jun. Current Situation of Foundation Works and Existing Problems for Transmission Lines in China[J]. Electric Power Construction, 2002, 23(3): 32-34.(in Chinese))
[2] 鲁先龙,程永锋.我国输电线路基础工程现状与展望[J].电力建设,2005,26(11):25-27,34.(LU Xian-long, CHENG Yong-feng. Current Status and Prospect of Transmission Tower Foundation Engineering in China[J]. Electric Power Construction, 2005, 26(11): 25-27, 34.(in Chinese))
[3] LI N, MEN Y, YUAN L, et al. Study on the Mechanical Characteristic of Micropiles Supporting Landslide under Step-Loadings[J]. Geotechnical and Geological Engineering, 2020, 38(3): 2761-2771.
[4] 陈再谦, 帅世杰, 蒲黍絛, 等. 微型桩抗弯承载力试验研究[J]. raybet体育在线
院报, 2020, 37(2): 100-105. (CHEN Zai-qian, SHUAI Shi-jie, PU Shu-tao, et al. Experimental Study on Flexural Bearing Capacity of Micropiles[J]. Journal of Yangtze River Scientific Research Institute, 2020, 37(2): 100-105.(in Chinese))
[5] 李 楠, 门玉明, 汪班桥, 等. 微型桩群桩支护均质土滑坡的振动台模型试验[J]. 工程地质学报, 2019, 27(6): 1371-1378. (LI Nan, MEN Yu-ming, WANG Ban-qiao, et al. Shaking Model Test on Soil Landslide Supported with Micropiles[J]. Journal of Engineering Geology, 2019, 27(6): 1371-1378.(in Chinese))
[6] 孙志亮, 孔令伟, 王 勇, 等. 悬臂挡墙–微型桩加固填土边坡地震响应特征研究[J]. 岩石力学与工程学报, 2022, 41(10): 2109-2123. (SUN Zhi-liang, KONG Ling-wei, WANG Yong, et al. Study on Seismic Response Characteristics of a Micropile-reinforced Filled Slope Behind a Cantilever Retaining Wall[J]. Chinese Journal of Rock Mechanics and Engineering, 2022, 41(10): 2109-2123.(in Chinese))
[7] KIM D, KIM G, KIM I, et al. Assessment of Load Sharing Behavior for Micropiled Rafts Installed with Inclined Condition[J]. Engineering Structures, 2018, 172: 780-788.
[8] 马朝阳. 输电线路新型钻孔微型桩基础应用研究[D]. 石家庄: 石家庄铁道大学, 2019. (MA Chao-yang. Application Research of New Bored Micro Pile Foundation for Transmission Line[D].Shijiazhuang: Shijiazhuang Tiedao University, 2019. (in Chinese))
[9] MORADI MOGHADDAM H, KERAMATI M, RAMESH A, et al. Experimental Evaluation of the Effects of Structural Parameters, Installation Methods and Soil Density on the Micropile Bearing Capacity[J]. International Journal of Civil Engineering, 2021, 19(11): 1313-1325.
[10]罗 辉, 张 锐, 聂如松, 等. 红层软岩钢管微型桩抗压承载特性试验[J]. 中国公路学报, 2022, 35(11): 97-106. (LUO Hui, ZHANG Rui, NIE Ru-song, et al. Experimental Study on Compressive Bearing Characteristics of Micro-steel-pipe Piles in Red-bed Soft Rock[J]. China Journal of Highway and Transport, 2022, 35(11): 97-106.(in Chinese))
[11]屈 伟, 朱 锐, 居 俊, 等. 黄土地区微型桩基础承载特性现场试验研究[J]. 建筑科学, 2020, 36(1): 98-105. (QU Wei, ZHU Rui, JU Jun, et al. Experimental Investigation on Bearing Characteristics of Micro Pile Foundation in Loess[J]. Building Science, 2020, 36(1): 98-105.(in Chinese))
[12]盛明强, 乾增珍, 杨文智, 等. 浸水饱和条件下黄土微型桩抗压和抗拔承载力试验[J]. 岩土工程学报, 2021, 43(12): 2258-2264. (SHENG Ming-qiang, QIAN Zeng-zhen, YANG Wen-zhi, et al. Field Compression and Uplift Tests on Micropiles in Collapsible Loess under Completely-soaked and Saturated Conditions[J]. Chinese Journal of Geotechnical Engineering, 2021, 43(12): 2258-2264.(in Chinese))
[13]AHMAD MALIK B, SHAH M Y, SAWANT V A. Plate Load Tests to Analyze the Load-settlement Response of Shallow Foundations on Sand Beds Reinforced with Micropiles[J]. Environmental Science and Pollution Research, 2021, 28(47): 67657-67666.
[14]王丽艳, 袁新明. 微型桩复合地基沉降和动力特性研究[J]. 水利学报, 2005, 36(12): 1492-1497. (WANG Li-yan, YUAN Xin-ming. Decline and Dynamic Characteristics of Micro-piles Reinforced Foundation[J]. Journal of Hydraulic Engineering, 2005, 36(12): 1492-1497.(in Chinese))
[15]李子曦,罗方悦,张 嘎.微型桩加固浅基础的离心模型试验研究[J].岩土工程学报,2021,43(增刊2):56-59.(LI Zi-xi, LUO Fang-yue, ZHANG Ga. Centrifugal Model Test Study on Reinforcement of Shallow Foundation with Micro-piles[J]. Chinese Journal of Geotechnical Engineering, 2021, 43(Supp.2): 56-59.(in Chinese))
[16]JGJ 106—2014,建筑基桩检测技术规范[S].北京:中国建筑工业出版社, 2014.(JGJ 106—2014,Technical code for testing of building foundation piles[S].Beijing:China Architecture and Building Press,2014.(in Chinese))
[17]豆鹏飞, 刘 浩, 许成顺, 等. 非液化场地中桩-结构体系地震响应与桩基失效模式分析[J]. 中国公路学报, 2022, 35(11): 39-51. (DOU Peng-fei, LIU Hao, XU Cheng-shun, et al. Seismic Response and Failure Mode Analysis of Pile-structure System in Non-liquefiable Site[J]. China Journal of Highway and Transport, 2022, 35(11): 39-51.(in Chinese))
[18]孙毅龙, 许成顺, 杜修力, 等. 海上风电大直径单桩的修正p-y曲线模型[J]. 工程力学, 2021, 38(4): 44-53. (SUN Yi-long, XU Cheng-shun, DU Xiu-li, et al. A Modified p-y Curve Model of Large-Monopiles of Offshore Wind Power Plants[J]. Engineering Mechanics, 2021, 38(4): 44-53.(in Chinese))
[19]MOAYED R Z, KAMALZARE M, JUDI A. Three-dimensional Analyses of Concrete Piles in Clayey Soils[J]. Proceedings of the Institution of Civil Engineers-Geotechnical Engineering, 2013, 166(4): 399-407.
[20]KANG S S, NOH J, JANG H. Support Characteristics of Eco-spiral Pile with Respect to Twisting Angle and Ratio of Borehole Diameter to Pile Width[J]. International Journal of Mining, Reclamation and Environment, 2019, 33(4): 265-285.
[21]周立朵,孔纲强,彭怀风,等.倾斜荷载下群桩承载特性理论分析[J].岩土力学,2017,38(9):2647-2654.(ZHOU Li-duo,KONG Gang-qiang,PENG Huai-feng,et al.Theoretical Analysis of Bearing Capacities of Pile Group under Oblique Load[J]. Rock and Soil Mechanics,2017,38(9):2647-2654.(in Chinese))
[22]史学明. 组合荷载作用下大直径扩底桩承载性状影响分析[D]. 淮南: 安徽理工大学, 2020. (SHI Xue-ming. Influence Analysis of Bearing Behavior of Large-diameter Bottomed Pile under Combined Load[D].Huainan: Anhui University of Science & Technology, 2020. (in Chinese))
[23]MEYERHOF G G,RANJAN G.The Bearing Capacity of Rigid Piles under Inclined Loads in Sand. II: Batter Piles[J].Canadian Geotechnical Journal,1973,10(1):71-85.
[24]KOUMOTO T, MEYERHOF G G, SASTRY V V R N. Analysis of Bearing Capacity of Rigid Piles under Eccentric and Inclined Loads[J]. Canadian Geotechnical Journal, 1986, 23(2): 127-131.
[25]李尚飞, 赵春风, 冼芳任, 等. 组合荷载作用下单桩的承载机理研究[J]. 广西大学学报(自然科学版), 2013, 38(4): 969-974. (LI Shang-fei, ZHAO Chun-feng, XIAN Fang-ren, et al. Bearing Mechanism of Single Pile under Combined Loads[J]. Journal of Guangxi University (Natural Science Edition), 2013, 38(4): 969-974.(in Chinese))
基金
国家电网公司科技项目(SGSCAB00JSJS1900683,SGSCDZ00JSJS2100272)
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