Geomechanics and Engineering

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Study on the root interaction characteristics and nonlinear deformation prediction of root piles

  • Jilu Zhang (School of Civil Engineering, Chongqing University) ;
  • Xiaohan Zhou (School of Civil Engineering, Chongqing University) ;
  • Xuefeng Huang (School of Civil Engineering, Lanzhou University of Technology) ;
  • Xinrong Liu (School of Civil Engineering, Chongqing University) ;
  • Jun Yuan (Northwest Electric Power Design Institute Co., Ltd. of China Power Engineering Consulting Group) ;
  • Xuelan Liang (Construction Branch of State Grid Qinghai Electric Power Company) ;
  • Juan Li (Qinghai Power Transmission and Transfer Engineering Co. Ltd.)
  • Received : 2022.12.24
  • Accepted : 2023.09.27
  • Published : 2023.11.10
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Abstract

As a new type of pile foundation, root piles have attracted more attention in the uplift design especially because of their unique structure. In this paper, based on the field tests the bearing capacity and load transfer law of straight pile, belled pile and roots pile were analysed. Results found the setting of multiple layers of roots along the pile depth can make the root resistance and skin friction resistance work simultaneously which improve the uplift resistance greatly. By using the numerical simulation tool, the uplift resistance of pile is analysed under the influence of different root length, density (number of roots) and spacing. It is found that increasing the root length and spacing can effectively improve the uplift resistance of the pile. However, the effect of increasing the spacing of roots is more significant. With increasing the roots density, the interaction development process between roots will assume to four main stages: stage I no interaction, stage II weak interaction, stage III strong interaction and stage IV strengthen. When the roots density is at stage II, there will be a high uplift resistance in addition to a little interaction. Finally, based on the load transfer method, a nonlinear deformation calculation method for the roots pile under uplift load were established. This method not only considered the influence of different stress conditions and roots positions on load distribution of roots, but also consider the influence of roots interaction at same layer and between layers on the uplift resistance.

Keywords

Acknowledgement

This work was supported by the Qinghai Electric Power Company Limited (52283820000A), the Northwest Electric Power Design Institute Co., Ltd. of China Power Engineering Consulting Group (XB1-TM05-2017) and the National Natural Science Foundation of China (Grant Nos. 41972266 and 41772319). Moreover, the authors gratefully thank the editors' and anonymous reviewers' suggestions and comments.

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