Through model tests based on digital image correlation technology and discrete element numerical simulation method (PFC), the influence of thread setting, the relative density of sand, loading conditions on the uplift bearing capacity, and deformation characteristics of the screw-shaft pile are studied. The test results are used to calibrate the micro parameters of the discrete element program. The simulation results are used to analyze the load sharing characteristics, the influence of pile type parameters on the bearing capacity and the sliding surface of the soil around the pile. The results show that: The uplift force-displacement curves of pile foundation present softening characteristics, and the 0.05D failure criterion is applicable to the determination of the ultimate bearing capacity of the uplift pile. The setting of the screw threads increases the bearing capacity of the pile by 37%, the load sharing ratio of the threaded section is close to 70%, and the shaft section is twice that of the compression condition. The uplift bearing capacity decreases with the increase of thread pitch. H/D=1.00 is a reasonable parameter under this condition. The improvement of the relative density of sand makes the uplift bearing capacity of screw-shaft pile and straight rod pile increase by 19.4% and 26% respectively, while the influence of displacement mode of soil around the uplift pile is limited. The maximum influence range of soil around the screw-shaft pile is about 4D, while that of straight rod pile is about 2D.
[1] 叶阳升, 蔡德钩, 陈晓斌, 等. 高速铁路螺杆桩复合地基桩侧摩阻力原位试验研究[J]. 中国铁道科学, 2020, 41(2): 1-10. (Ye Yangsheng, Cai Degou, Chen Xiaobin, et al. In-situ test study on lateral friction of screw pile composite foundation of high speed railway [J]. China Railway Science, 2020, 41(2): 1-10. (in Chinese))
[2] 陈亚东, 于艳, 董云, 等. 竖向受荷螺杆桩工作性状试验研究[J]. 地下空间与工程学报, 2022, 18(3): 860-867. (Chen Yadong, Yu Yan, Dong Yun, et al. Experimental study on working behavior of vertically loaded screw-shaft pile [J]. Chinese Journal of Underground Space and Engineering, 2022, 18(3): 860-867. (in Chinese))
[3] Alawneh A S, Nusier O K, Sharo' A A. Poisson's ratio effect on compressive and tensile shaft capacity of driven piles in sand: Theoretical formulation [J]. Computers and Geotechnics, 2007, 34(3): 151-163.
[4] 王斌, 钱建固, 陈宏伟, 等. 注浆成型螺纹桩抗拔承载特性的数值分析[J]. 岩土力学, 2014, 35(增2): 572-578. (Wang Bin, Qian Jiangu, Chen Hongwei, et al. Numerical analysis of grouting-screw pile uplift bearing capacity [J]. Rock and Soil Mechanics, 2014, 35(Supp.2): 572-578. (in Chinese))
[5] Fahmy A, El Naggar M H. Axial and lateral performance of spun-cast ductile iron helical tapered piles in clay [J]. Proceedings of the Institution of Civil Engineers-Geotechnical Engineering, 2017, 170(6): 503-516.
[6] 董天文, 梁力, 王炜, 等. 抗拔螺旋桩叶片与地基相互作用试验研究[J]. 工程力学, 2008, 25(8) : 150-155, 163. (Dong Tianwen, Liang Li, Wang Wei, et al. Experimental analysis on the lamina-soils interaction in pullout screw pile foundation [J]. Engineering Mechanics, 2008, 25(8): 150-155, 163. (in Chinese))
[7] Mitsch M P, Clemence S P. The uplift capacity of helix anchors in sand [A]//Proceedings of Uplift Behavior of Anchor Foundations in Soil [C]. 1985: 26-47.
[8] Mooney J S, Adamczak S, Clemence S P. Uplift capacity of helical anchors in clay and silt [A]//Proceedings of Uplift Behavior of Anchor Foundations in Soil [C]. 1985: 48-72.
[9] Bagheri F, El Naggar M H. Effects of installation disturbance on behavior of multi-helix piles in structured clays [J]. DFI Journal - The Journal of the Deep Foundations Institute, 2016, 9(2): 80-91.
[10] Mohajerani A, Bosnjak D, Bromwich D. Analysis and design methods of screw piles: a review [J]. Soils & Foundations, 2016, 56(1): 115-128.
[11] Livneh B, El Naggar M H. Axial testing and numerical modeling of square shaft helical plies under compressive and tensile loading [J]. Canadian Geotechnical Journal, 2008, 45(8): 1142-1155.
[12] Sakr M. Relationship between installation torque and axial capacities of helical piles in cohesionless soils [J]. Canadian Geotechnical Journal, 2015, 52(6): 747-759.
[13] George B E, Banerjee S, Gandhi S R. Helical piles installed in cohesionless soil by displacement method [J]. International Journal of Geomechanics, 2019, 19(7): 1-18.
[14] Nazir R, Chuan H S, Niroumand H, et al. Performance of single vertical helical anchor embedded in dry sand [J]. Measurement, 2014, 49: 42-51.
[15] Aoyama S, Mao W W, Goto S, et al. Application of advanced procedures to model tests on the subsoil behavior under vertical loading of group pile in sand [J]. Indian Geotechnical Journal, 2016, 46(1): 64-76.
[16] Chen Y, Deng A, Wang A, et al. Performance of screw-shaft pile in sand: model test and DEM simulation [J]. Computers and Geotechnics, 2018, 104: 118-130.
[17] 曹兆虎, 孔纲强, 刘汉龙, 等. 基于PIV技术的沉桩过程土体位移场模型试验研究[J]. 工程力学, 2014, 31(8): 168-174. (Cao Zhaohu, Kong Gangqiang, Liu Hanlong, et al. Model test on deformation characteristic of pile driving in sand using PIV technique [J]. Engineering Mechanics, 2014, 31(8): 168-174. (in Chinese))
[18] Bolton M D, Gui M W, Garnier J, et al. Centrifuge cone penetration tests in sand [J]. Geotechnique, 1999, 49(4): 543-552.
[19] Azzam W R, Elwakil A Z. Model study on the performance of single-finned pile in sand under tension loads [J]. International Journal of Geomechanics, 2016, 17(3): 04016072.
[20] 张家文, 邢文豪, 蒋仕清, 等. 浅埋隧道施工对上覆地层变形影响的试验研究[J]. 地下空间与工程学报, 2022, 18(4): 1233-1240. (Zhang Jiawen, Xing Wenhao, Jiang Shiqing, et al. Experimental study on the effect of shallow tunnel construction on deformation of overlying strata [J]. Chinese Journal of Underground Space and Engineering, 2022, 18(4): 1233-1240. (in Chinese))
[21] Sakr M. Performance of helical piles in oil sand [J]. Canadian Geotechnical Journal, 2009, 46(9): 1046-1061.
[22] Alawneh A S, Malkawi A I H, Aldeeky H. Tension tests on smooth and rough model piles in dry sand [J]. Canadian Geotechnical Journal, 1999, 36(4): 746-753.
[23] Huang X, Hanley K J, O'sullivan C, et al. Influence of inter-particle friction on critical state behaviour [J]. International Journal for Numerical & Analytical Methods in Geomechanics, 2014, 38(12): 1276-1297.
[24] Shi D, Yang Y, Deng Y, et al. DEM modelling of screw pile penetration in loose granular assemblies considering the effect of drilling velocity ratio [J]. Granular Matter, 2019, 21(3): 1-16.
[25] Lobo-Guerrero S, Vallejo L E. Influence of pile shape and pile interaction on the crushable behavior of granular materials around driven piles: DEM analyses [J]. Granular Matter, 2007, 9(3-4): 241-250.
[26] Chen Y, Deng A, Lu F, et al. Failure mechanism and bearing capacity of vertically loaded pile with partially-screwed shaft: experiment and simulations [J]. Computers and Geotechnics, 2020, 118: 103337.
