JZUS - Journal of Zhejiang University SCIENCE

Journal of Zhejiang University SCIENCE A 2020 Vol.21 No.3 P.179-192

http://doi.org/10.1631/jzus.A1900590

Nonlinear analysis of pile groups subjected to combined lateral and torsional loading

Author(s): Ling-gang Kong, Zhong-chang Zhang, Yun-min Chen
Affiliation(s): Institute of Geotechnical Engineering, College of Architectural and Civil Engineering, Zhejiang University, Hangzhou 310058, China
Corresponding email(s): klg@zju.edu.cn
Key Words: Combined lateral and torsional loading, Pile groups, Twist center, p-multiplier, Group effect

Share this article to： More <<< Previous Article \|Next Article >>>

Abstract: An empirical approach has been developed to analyze the nonlinear response of a pile group with arbitrarily distributed piles subjected to combined lateral and torsional loading. In this approach, the concept of instantaneous twist center is applied to analyze the displacement relationship of pile heads and establish the static equilibrium equations of the pile cap. The horizontal interaction among the individual piles is considered through the generalized p-multiplier. The coupling effect of lateral resistance on the torsional resistance of each pile is quantified using an empirical factor β; the lateral and torsional nonlinear responses of individual piles are modeled by p-y and τ-θ curves, respectively. The proposed approach not only captures the most significant aspect of the group effect and coupling effect in a pile group subjected to combined lateral and torsional loading, but also automatically updates p-multipliers of individual piles based on pile cap displacements. The proposed approach was verified using results of model tests on pile groups subjected to lateral loading, torsional loading, and combined lateral and torsional loading, separately. In general, the pile cap response and the transfer of applied loads in the pile groups agree well with the test results.

水平偏心受荷群桩的非线性分析

目的:群桩基础在近海建/构筑物及桥梁中广泛应用,而风、浪、船舶撞击等在群桩基础中产生的水平和扭转荷载往往影响群桩基础的安全. 本文旨在提出一套能够计算水平和扭转荷载联合作用下的群桩非线性响应简化分析方法.
创新点:1. 采用广义p乘子法考虑群桩中各桩水平变形导致的桩-土-桩相互作用; 2. 建立基于瞬时转动中心的基桩桩头位移关系和承台平衡方程.
方法:1. 通过理论分析给出基桩桩头位移之间的关系,建立承台平衡方程; 2. 采用荷载传递模型(p-y和τ-θ曲线)模拟桩周土体非线性响应; 3. 采用广义p乘子法考虑群桩中各桩水平变形导致的桩-土-桩相互作用,并采用耦合因子计算基桩中推-扭耦合响应; 4. 通过迭代方法求解各基桩p乘子和群桩响应.
结论:1. 多组算例均表明本文提出的群桩非线性分析模拟能够较准确地模拟群桩响应,尤其在承台位移较大的情况下; 2. 广义p乘子能够有效地模拟群桩效应的主要部分; 3. 模型中的简化公式能够应用于实际工程问题分析.
关键词：水平和扭转组合荷载; 群桩; 转动中心; p乘子; 群桩效应

Reference

[1]Brown DA, Morrison C, Reese LC, 1988. Lateral load behavior of pile group in sand. Journal of Geotechnical Engineering, 114(11):1261-1276.

[2]Chen SL, Kong LG, Zhang LM, 2016. Analysis of pile groups subjected to torsional loading. Computers and Geotechnics, 71:115-123.

[3]Gu M, Kong LG, Chen RP, et al., 2014. Response of 1×2 pile group under eccentric lateral loading. Computers and Geotechnics, 57:114-121.

[4]He W, Chen RP, Kong LG, et al., 2010. Bearing behaviors and nonlinear theory of pile groups subjected to torque. Chinese Journal of Geotechnical Engineering, 32(5):751-756 (in Chinese).

[5]Hu ZH, McVay M, Bloomquist D, et al., 2006. Influence of torque on lateral capacity of drilled shafts in sands. Journal of Geotechnical and Geoenvironmental Engineering, 132(4):456-464.

[6]Kong LG, 2006. Behaviour of Pile Groups Subjected to Torsion. PhD Thesis, The Hong Kong University of Science and Technology, Hong Kong, China.

[7]Kong LG, Zhang LM, 2007. Centrifuge modeling of torsionally loaded pile groups. Journal of Geotechnical and Geoenvironmental Engineering, 133(11):1374-1384.

[8]Kong LG, Zhang LM, 2008a. Effect of pile-cap connection on behavior of torsionally loaded pile groups. Journal of Zhejiang University-SCIENCE A, 9(3):303-312.

[9]Kong LG, Zhang LM, 2008b. Experimental study of interaction and coupling effects in pile groups subjected to torsion. Canadian Geotechnical Journal, 45(7):1006-1017.

[10]Kong LG, Zhang LM, 2009. Nonlinear analysis of torsionally loaded pile groups. Soils and Foundations, 49(2):275-286.

[11]Kong LG, Chen RP, Wang SH, et al., 2015. Response of 3×3 pile groups in silt subjected to eccentric lateral loading. Journal of Geotechnical and Geoenvironmental Engineering, 141(7):04015029.

[12]Kong LG, Fan JY, Liu JW, et al., 2019. Group effect in piles under eccentric lateral loading in sand. Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 20(4):243-257.

[13]Li Q, Stuedlein AW, 2018. Simulation of torsionally loaded deep foundations considering state-dependent load transfer. Journal of Geotechnical and Geoenvironmental Engineering, 144(8):04018053.

[14]Li Q, Stuedlein AW, Barbosa AR, 2019. Role of torsional shear in combined loading of drilled shaft foundations. Journal of Geotechnical and Geoenvironmental Engineering, 145(4):06019001.

[15]Li ZF, 2015. Response and Effect Factors of Pile Groups Subjected to Eccentric Lateral Loading. MS Thesis, Zhejiang University, Hangzhou, China (in Chinese).

[16]McVay M, Casper R, Shang TI, 1995. Lateral response of three-row groups in loose to dense sands at 3D and 5D pile spacing. Journal of Geotechnical Engineering, 121(5):436-441.

[17]Mehra S, Trivedi A, 2018. Experimental studies on model single pile and pile groups subjected to torque. In: Wu W, Yu HS (Eds.), Proceedings of China-Europe Conference on Geotechnical Engineering. Springer, Cham, Switzerland, p.997-1000.

[18]Randolph MF, 1980. PIGLET: a Computer Program for the Analysis and Design of Pile Groups under General Loading Conditions. Soil Report TR91, University of Cambridge, Cambridge, UK.

[19]Reese LC, Cox WR, Koop FD, 1974. Analysis of laterally loaded piles in sand. Proceedings of the 6th Annual Offshore Technology Conference, p.473-485.

[20]Reese LC, Wang ST, Vasquez L, 2006. Computer Program GROUP 7.0—Technical Manual. Ensoft, Inc., Austin, USA.

[21]Smith IM, Griffiths DV, Margetts L, 2015. Programming the Finite Element Method, 5th Edition. John Wiley & Sons, Chichester, UK.

[22]Xu KJ, Poulos HG, 2000. General elastic analysis of piles and pile groups. International Journal for Numerical and Analytical Methods in Geomechanics, 24(15):1109-1138.

[23]Xue J, Gavin K, Murphy G, et al., 2016. Optimization technique to determine the p-y curves of laterally loaded stiff piles in dense sand. Geotechnical Testing Journal, 39(5):842-854.

Open peer comments: Debate/Discuss/Question/Opinion

<1>

Similar articles

- Go to

水平偏心受荷群桩的非线性分析

Darkslateblue:Affiliate; Royal Blue:Author; Turquoise:Article

Reference