Geomechanics and Engineering

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Prediction of the load-displacement response of ground anchors via the load-transfer method

  • Chalmovsky, Juraj (Department of Geotechnics, Faculty of Civil Engineering, Brno University of Technology) ;
  • Mica, Lumir (Department of Geotechnics, Faculty of Civil Engineering, Brno University of Technology)
  • Received : 2019.08.27
  • Accepted : 2020.02.04
  • Published : 2020.02.25
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Abstract

Prestressed ground anchors are important structural elements in geotechnical engineering. Despite their widespread usage, the design process is often significantly simplified. One of the major drawbacks of commonly used design methods is the assumption that skin friction is mobilized uniformly along an anchor's fixed length, one consequence of which is that a progressive failure phenomenon is neglected. The following paper introduces an alternative design approach - a computer algorithm employing the load-transfer method. The method is modified for the analysis of anchors and combined with a procedure for the derivation of load-transfer functions based on commonly available laboratory tests. The load-transfer function is divided into a pre-failure (hardening) and a post-failure (softening) segment. In this way, an aspect of non-linear stress-strain soil behavior is incorporated into the algorithm. The influence of post-grouting in terms of radial stress update, diameter enlargement, and grout consolidation is included. The axial stiffness of the anchor body is not held constant. Instead, it gradually decreases as a direct consequence of tensile cracks spreading in the grout material. An analysis of the program's operation is performed via a series of parametric studies in which the influence of governing parameters is investigated. Finally, two case studies concerning three investigation anchor load tests are presented.

Keywords

Acknowledgement

Supported by : Ministry of Industry and Trade

This research was supported by Ministry of Industry and Trade research project No. FR-TI4/329. The authors would also like to thank Ing. Peter Misove, CSc. (VUIS Special Foundations, Slovakia) for making his data and research available. Discussions with Dr. Vaclav Racansky (Keller Grundbau, Austria) are highly appreciated.

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