Cyclic Thermomechanical Response of Fine-Grained Soil-Conrete Interface for Energy Piles Applications

Jul 2, 2026

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Understanding soil–structure interfaces is essential for analyzing and designing energy geostructures, especially energy piles exposed to cyclic thermal loads. This laboratory study experimentally examines the interface failure mechanism under saturated conditions, focusing on clayey soil and concrete materials. Cyclic thermal tests are performed under constant vertical effective stress in oedometric conditions and constant normal stiffness direct shear tests with thermal cycling between 10 and 40 °C. Results indicate very low volumetric strain changes and negligible impact on shear strength.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages15

Reading Time38 min

Abstract

Introduction

Can. . .Geotech J Downloaded from cdnsciencepub .com by UNIVERSITY OF NEWCASTLE on 07/02/26 For personal use only . 1216 ARTICLE Cyclic thermomechanical response of ﬁne-grained soil􀀁concrete interface for energy piles applications Elena Ravera, Melis Sutman, and Lyesse Laloui Abstract: Understanding the behaviour of soil􀀁structure interfaces is critical for addressing the analysis and design of energy geostructures. In this study, the interface failure mechanism of energy piles (where a shear band is detached from the surrounding soil that behaves under oedometric conditions) is experimentally analysed in the laboratory for saturated conditions. The choice of material (clayey soil and concrete), temperature range, and stress level is based on conditions that are likely to be encountered in practice. Speciﬁcally, cyclic thermal tests under constant vertical effective stress in oedometric conditions as well as constant normal stiffness (CNS) interface direct shear tests (in which samples have been subjected to thermal cycles between 10 and 40 °C) are presented. From a practical perspective, the results show very low volumetric strain variations and negligible effects on shear strength. The volumetric aspects do not appear to have signiﬁcant impact on the shear resistance of the interfaces against cyclic thermal loads. Fundamental insight on the effects of thermal cycleson the concrete􀀁soil interface behaviour that are relevant to energy piles are presented. In addition, the proposed interpretation procedure provides a basis for the standardization of thermomechanical testing in geotechnical engineering. Key words: energy piles, soil􀀁concrete interface, thermomechanical behaviour, laboratory testing, cyclic load. Résumé : Il est crucial de comprendre le comportement des interfaces sol􀀁structure avant de pouvoir aborder l ’analyse et la conception des géostructures énergétiques. Le mécanisme de rupture de l ’interface des pieux énergétiques (où une bande de cisaillement se détache du sol environnant qui se comporte dans des conditions œdométriques) est analysé expérimentalement en laboratoire pour des conditions de saturation. Quant au choix du matériau (sol argileux et béton), de la plage de température et du niveau de contrainte, celui-ci est basé sur les conditions susceptibles de se présenter dans la pratique. On présente notamment des essais thermiques cycliques sous contrainte verticale effective constante dans des conditions œdométriques ainsi que des essais de cisaillement direct d’interface à rigidité normale constante (CNS) (dont les échantillons ont été soumis à des cycles thermiques entre 10 et 40 °C) . Les résultats obtenus révèlent de très faibles variations de la déformation volumétrique et des conséquences négligeables sur la résistance au cisaillement. Il ne semble pas que les aspects volumétriques aient un impact signiﬁcatif sur la résistance au cisaillement des interfaces contre les charges thermiques cycliques. Des connaissances fondamentales sur les effets des cycles thermiques sur le comportement de l’interface béton􀀁sol qui sont pertinentes pour les pieux énergétiques sont présentées. Par ailleurs, la procédure d’interprétation qui estenvisagée fournit une référence pour la normalisation des essais thermomécaniques en géotechnique. [Traduit par la Rédaction] Mots-clés : pieux énergétiques, interface sol􀀁béton, comportement thermomécanique, essais en laboratoire, charge cyclique. 1. Introduction In geotechnical engineering, the study of non-isothermal soil behaviour dates back to the 1950s and 1960s. During that time, the focus was on understanding the effects of temperature on engineering properties, generating thermal pressurization for saturated soils, and soil sampling. From the 1970s to the 1990s, several new geotechnical applications that required understanding of the behaviour of soils subjected to temperature changes (e.g., design in permafrost regions, nuclear waste storage, burie

FAQs

What interface failure mechanism is investigated for energy piles?

The study analyzes the interface failure mechanism where a shear band detaches from the surrounding soil that behaves under oedometric conditions.

How are cyclic thermal effects applied in the experiments?

Cyclic thermal tests are conducted under constant vertical effective stress in oedometric conditions, and constant normal stiffness (CNS) interface direct shear tests are performed with thermal cycles between 10 and 40 °C.

What do the results show about volumetric strain and shear strength?

The findings indicate very low volumetric strain variations and negligible effects on shear strength, suggesting volumetric aspects do not significantly influence interface resistance under cyclic thermal loading.

Jul 2, 2026

Upload by Aurora