Nonlinear Analysis on Bearing Characteristics of Flexible Piled Raft Foundations in Non-homogeneous Cohesive Soil under Excavation

JIU Yong-zhi; ZHANG Zhen; LI Jian; SHEN Huan; SONG Zhen-hong

doi:10.11988/ckyyb.20200630

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Journal of Changjiang River Scientific Research Institute ›› 2021, Vol. 38 ›› Issue (8) : 112-119. DOI: 10.11988/ckyyb.20200630

ROCK-SOIL ENGINEERING

Nonlinear Analysis on Bearing Characteristics of Flexible Piled Raft Foundations in Non-homogeneous Cohesive Soil under Excavation

JIU Yong-zhi^1,2,3, ZHANG Zhen¹, LI Jian⁴, SHEN Huan⁴, SONG Zhen-hong⁴

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Abstract

A simplified nonlinear approach for analyzing flexible piled raft foundation in non-homogeneous cohesive soil under excavation is proposed to investigate the influence of excavation on the bearing capacity of the foundation. The flexible piled raft is modeled as a thin plate through the finite element discretization. With the impact of soil excavation around the pile into consideration, the flexibility coefficient of pile top in non-homogeneous cohesive soil under excavation is obtained by employing the load transfer method; based on solutions for the stress and displacement in layered elastic half space, the interactions of the pile group-soil system are taken into account to determine the flexibility matrix of the pile group-soil system in non-homogeneous cohesive soil under excavation. By integrating finite element method and finite difference method, the simplified nonlinear analysis method is obtained. Comparison between calculated results and test and theoretical results verified the validity of the present method. With the influence of soil excavation ignored, the load sharing ratio of soil in piled raft foundation will be underestimated, and the non-uniformity of load distribution at the top of foundation pile at the bottom of raft will be larger in the analysis results. The research results offer a basis for balance design for variable-rigidity of group piled foundation and piled raft foundation under excavation.

Key words

piled raft foundations / nonlinear analysis / unloading rebound of soil / non-homogeneous foundation / pit excavation

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JIU Yong-zhi, ZHANG Zhen, LI Jian, SHEN Huan, SONG Zhen-hong. Nonlinear Analysis on Bearing Characteristics of Flexible Piled Raft Foundations in Non-homogeneous Cohesive Soil under Excavation[J]. Journal of Changjiang River Scientific Research Institute. 2021, 38(8): 112-119 https://doi.org/10.11988/ckyyb.20200630

References

[1] IWASAKI Y, WATANABE H, FUKUDA M, et al. Construction Control for Underpinning Piles and Their Behavior during Excavation[J]. Geotechnique, 1994, 44(4):681-689.
[2] 刁钰. 超深开挖对坑底抗压桩竖向承载力及沉降特性影响研究[D]. 天津: 天津大学, 2011.
[3] 陈锦剑, 吴琼, 王建华, 等. 开挖卸荷条件下单桩承载力特性的模型试验研究[J]. 岩土工程学报, 2010, 32(增刊2): 85-88.
[4] 罗耀武, 胡琦, 陈云敏, 等. 基坑开挖对抗拔桩极限承载力影响的模型试验研究[J]. 岩土工程学报, 2011, 33(3): 427-432.
[5] 纠永志,黄茂松.开挖条件下黏土中单桩竖向承载特性模型试验与分析[J].岩土工程学报,2016,38(2):202-209.
[6] 胡琦, 凌道盛, 陈云敏, 等. 深基坑开挖对坑内基桩受力特性的影响分析[J].岩土力学,2008,29(7):1965-1970.
[7] 陈锦剑, 王建华, 范巍, 等. 抗拔桩在大面积深开挖过程中的受力特性分析[J]. 岩土工程学报, 2009, 31(3): 402-407.
[8] 黄茂松, 郦建俊, 王卫东, 等. 开挖条件下抗拔桩的承载力损失比分析[J]. 岩土工程学报, 2008, 30(9): 1291-1297.
[9] 郑刚, 张立明, 刁钰. 开挖条件下坑底工程桩工作性状及沉降计算分析[J]. 岩土力学, 2011, 32(10): 3089-3096.
[10]刁钰,李光帅,郑刚. 超深开挖对坑底桩的抗压承载力及沉降特性的影响因素研究[J]. 岩土工程学报, 2017, 39(增刊2): 207-211.
[11]郑刚, 王琦, 张立明. 基坑开挖对坑底工程桩性能影响参数分析[J]. 建筑结构, 2015, 45(21): 63-69.
[12]王成华, 刘庆晨. 考虑基坑开挖影响的群桩基础竖向承载性状数值分析[J]. 岩土力学, 2012, 33(6):1851-1856.
[13]伍程杰, 俞峰, 龚晓南, 等.开挖卸荷对既有群桩竖向承载性状的影响分析[J].岩土力学,2014,35(9):2602-2608.
[14]卫凌云, 秦胜伍, 陈慧娥. 基坑开挖对单桩及群桩回弹位移的影响分析[J]. 吉林大学学报(地球科学版), 2014, 44(2): 584-590.
[15]贾强, 黄坤, 王家奇, 等. 桩周土开挖状态下桩基础荷载传递规律研究[J]. 山东建筑大学学报,2019,34(1):1-5.
[16]纠永志,祝彦知.开挖条件下非均质地基中单桩竖向承载特性非线性分析[J].岩土力学,2017,38(6):1666-1674.
[17]HUANG Mao-song, JIU Yong-zhi, JIANG Jie, et al. Nonlinear Analysis of Flexible Piled Raft Foundations Subjected to Vertical Loads in Layered Soils[J]. Soils and Foundations, 2017, 57: 632-644.
[18]纠永志,黄茂松.超固结软黏土的静止土压力系数与不排水抗剪强度[J]. 岩土力学, 2017,38(4):951-957,964.
[19]CAPUTO V, VIGGIANI C. Pile Foundation Analysis: A Simple Approach to Nonlinearity Effects[J]. Rivista Italiana di Geotecnica, 1984, 18(2):31-51.
[20]O'NEILL M W. Field Study of Pile Group Action: Final Report. Report FHWA RD-81-002[R]. Washington, DC: Federal Highway Administration, U.S. Department of Transportation, 1981.
[21]KRAFT L M, RAY R P, KAGAWA T. Theoretical t-z Curves[J]. Journal of the Geotechnical Engineering Division, ASCE, 1981, 107(11): 1543-1561.
[22]LEE K M, XIAO Z R. A Simplified Nonlinear Approach for Pile Group Settlement Analysis in Multilayered Soils[J]. Candian Geotechnical Journal, 2001, 38(5):1063-1080.
[23]COMODROMOS E M, PAPADOPOULOU M C, RENTZEPERIS L K, et al. Pile Foundation Analysis and Design Using Experimental Data and 3-d Numerical Analysis[J]. Computers and Geotechnics, 2009, 36: 819-836.