Long-term thermo-mechanical behaviour of energy piles in clay

van Tri Nguyen (1) , Nanwangzi Wu (2) , Yixiang Gan (2) , Jean-Michel Pereira (1) , Anh Minh A.M. Tang (1)

1 navier umr 8205 - Laboratoire Navier
2 The University of Sydney

In engineering practice, energy pile foundations are often designed for the lifetime of the building. Thermal exchange between a pile and the surrounding soil depends on the annual energy needs of the building, as heating mode in winter and cooling mode in summer. Thus, energy pile foundations will undergo a heating–cooling cycle per year. In the present work, an experimental method based on a small-scale pile model installed in saturated clay was used to study the thermo-mechanical behaviour of energy piles under thermal cycles. Thirty cycles were applied (to represent a 30-year period if the daily cycles are neglected) while a constant pile head load was maintained. Four tests were performed corresponding to pile head loads equal to 0, 20, 40 and 60% of pile resistance. The results obtained show an increase in irreversible pile head settlement with the thermal cycles. In order to interpret the experimental results better, the finite-element method is used to simulate the experiments numerically. This allows the important role of pile thermal contraction/expansion in the pile–soil interaction under thermo-mechanical loading to be highlighted.

Mots clés: energy pile; numerical modelling; physical modelling; saturated clay; thermal cycles; thermo-mechanical behaviour.

Domaines: Géotechnique

van Tri Nguyen, Nanwangzi Wu, Yixiang Gan, Jean-Michel Pereira, Anh Minh A.M. Tang. Long-term thermo-mechanical behaviour of energy piles in clay. Environmental Geotechnics, 2020, 7 (4), pp.237-248. ⟨10.1680/jenge.17.00106⟩. ⟨hal-02879341⟩