Laboratory-scale thermo-activated piles under long continuous operation and different mobilised shaft resistance

Acta Geotechnica, vol. 19, pp. 6787–6808

Abstract

Abstract This paper examines the shaft resistance mobilisation ratio as a predictor of cumulative displacement of small-scale floating and end-bearing energy pile foundations subjected to vertical compressive loads embedded in dry sandy soils. A reduced friction model pile was subjected to different mechanical loads and two long-duration, cyclic heating/recovery temperature changes. The pile, soil and container temperatures, pile strains, and vertical displacements are monitored, analysed, and discussed. The results further validate numerical analyses that propose the shaft resistance mobilisation ratio as a variable to identify thresholds above which permanent cyclic thermo-induced deformations may occur. Overall, the experimentally observed responses indicate incremental deformations as the shaft resistance mobilisation ratio increased. The results also suggest that a mobilisation ratio of 66% could be a potential conservative lower-bound limit that could control the increment of thermal-induced vertical displacements in the long term under free pile head conditions. This suggests that a performance-based design would be a reasonable approach for energy piles, and monitoring programs should be set in the field before loading and thermo-activation.

Authors 5

1. Luis Villegas corresponding Aachen Institute of Geomechanics and Underground Technology

   The University of Melbourne · RWTH Aachen University

   Affiliation as printed

   Department of Infrastructure Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia

   Institute of Geomechanics and Underground Technology, RWTH Aachen University, Aachen, Germany

2. Amin Rafiei

   University College London

   Affiliation as printed

   Department of Civil, Environmental and Geomatic Engineering, University of College London, London, UK

3. Guillermo Andres Narsilio

   The University of Melbourne

   Affiliation as printed

   Department of Infrastructure Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia

4. Chanakya Arya

   University College London

   Affiliation as printed

   Department of Civil, Environmental and Geomatic Engineering, University of College London, London, UK

5. Raúl Fuentes Aachen Institute of Geomechanics and Underground Technology

   RWTH Aachen University

   Affiliation as printed

   Institute of Geomechanics and Underground Technology, RWTH Aachen University, Aachen, Germany