Influence of Reaction System on Uplift Behaviour of Micropiles Subjected to Static Pullout

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Traditionally, static tension load tests are required to prove the suitability of piling systems, and to confirm the design parameters estimated from the site investigation. During the loading procedure the reaction system counteracts the upheaval movement of the tested pile resulting in an overestimation of both, the uplift bearing capacity and the pile stiffness. Although this phenomenon, referred to as bracing effect, is widely recognised by execution standards it still lacks physical evidence. In this context, the present contribution focuses on the mutual interaction between the reaction system and test pile with particular emphasis on micropiles. The presented study has been partly carried out in the scope of the research project “Durability in Anchor Technique” (DAT), and involves both full-scale field tests as well as numerical studies based on validated models. The results showcase the bracing effect on the monitored micropile response, albeit being considerably reduced compared to previous studies concerning static load tests of large diameter piles; this observation supports the exception clauses of many execution standards that alleviate the geometrical requirements for load testing of micropiles. Since the bracing effect is pronounced in the near surface, the response of short micropiles is expected to be particularly prone to mutual locking. Consequently, future work should focus on its role during static loading of short micropiles with low slenderness ratio.
Original languageEnglish
Title of host publicationProceedings of the 11th International Symposium on Field Monitoring in Geomechanics
Number of pages7
Publication statusPublished - 6 Sept 2022
Event11th International Symposium on Field Monitoring in Geomechanics: ISFMG 2022 - Imperial College , London, United Kingdom
Duration: 4 Sept 20227 Sept 2022


Conference11th International Symposium on Field Monitoring in Geomechanics
Abbreviated titleISFMG 2022
Country/TerritoryUnited Kingdom
Internet address


  • micropile
  • pullout
  • bracing effect
  • field test
  • embedded beam

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Computational Mechanics

Fields of Expertise

  • Sustainable Systems


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