Experimental and numerical investigation of the thermo-mechanical behaviour of an energy sheet pile wall

One-of-a-kind experimental and numerical investigation is provided in this paper about energy sheet pile walls: earth retaining structures that embed heat exchanger probes within piles for the exploitation of shallow geothermal energy. The study resorts to the results of full-scale in situ tests and coupled three-dimensional thermo-mechanical finite element analyses of an energy sheet pile wall constructed in an underground station. In this context, an investigation about the influence of thermal boundary and initial conditions on thermo-mechanical behaviour of the energy sheet pile wall is performed. The addressed thermal boundary conditions are associated with the thermal load imposed on the considered foundation by the field environment and the geothermal operation of some energy piles constituting the wall. The addressed thermal initial conditions are associated with the undisturbed ground temperature field of the considered site. Based on a comparison between the experimental and numerical results, and the development of numerical sensitivity analyses, criticalities associated with the analysis and modelling of the thermo-mechanical behaviour of energy sheet pile walls are denoted. The results highlight that: a marked non-uniformity of the temperature field can characterise real applications of energy sheet pile walls, representing a significant challenge to capture numerically at all spatial locations; a comparable influence denotes thermal loads that derive from the field environment and the geothermal operation of energy sheet pile walls, deserving attention when modelling the behaviour of such geostructures; and a critical role of the initial thermal conditions is connected to the satisfactory understanding and prediction of the thermo-mechanical behaviour of energy sheet pile walls, requiring careful consideration for analysis and design purposes. (C) 2020 Elsevier Ltd. All rights reserved.

Experimental and numerical investigation of the thermo-mechanical behavior of an energy sheet pile wall

Lyesse Laloui, Alessandro Francesco Rotta Loria

2020

Parametric scripting for early design performance simulation

Guillaume Labelle

This paper discusses the advantages of using a coding interface both to describe form and run performance simulations in the context of architectural design. It outlines the relevance of combining recent interest in the design community for parametric scripting with available expert-level Building Performance Simulation. This approach enables designers to address performance-related design questions at the early design stage. Pitfalls when considering non-standard solutions and the potential of the approach to circumvent such difficulties are exemplified through a housing building case study, emphasizing the under-evaluated role of the analysis tool in steering design decisions. To circumvent the difficulty for non-expert users to interpret simulation results and transform them into design moves, the use of sensitivity analysis is proposed for its specific interplay with parametric scripting. Its potential for classifying parameters in order of importance is presented in the context of a design problem. The contribution outlines how providing designers with exploratory tools allows to consider sustainable construction in a systemic manner. (C) 2013 Elsevier B.V. All rights reserved.

Elsevier Science Sa2014

Thermo-mechanical performance of energy pile groups

Alessandro Francesco Rotta Loria

Employing geostructures as structural supports and geomaterials as reservoirs for the extraction and storage of heat represent effective means to meet human activity needs since ancient times. This doctoral thesis focuses on the thermo-mechanical behaviour and performance of an innovative, multifunctional technology that couples the aforementioned roles for the structural support and energy supply of any type of built environment, i.e., energy piles. The multifunctional role of energy piles involves mechanical and thermal loads applied to such geostructures. These loads pose unprecedented challenges to engineers because they cause variations in the temperature, stress, deformation and displacement in the subsurface that need to be considered during analysis and design. Prior to this work, a substantial amount of research had been made available to address the thermo-mechanical performance of single energy piles. Design guidance has also been proposed to advise in the geotechnical and structural design of such geostructures. However, energy pile foundations do not consist of a single energy pile but of a group of energy piles. In this framework, (i) limited knowledge, if available, was present to address the thermo-mechanical behaviour and performance of energy pile groups subjected to thermal and mechanical loads; (ii) no simplified models and methods were accessible to perform the analysis and design of energy pile groups against the action of such loads; and (iii) no comprehensive framework for the effect of thermal (and mechanical) loads on the performance and the related design of both single and groups of energy piles was avail-able. To address such challenges, this doctoral research was performed to (i) investigate the thermo-mechanical behaviour and performance of energy pile groups over typical time-scales of practical applications via the first available in situ tests and coupled numerical analyses of such geostructures; (ii) provide the only simplified analytical models and methods for predicting the vertical deformation of energy pile groups subjected to thermal and mechanical loads; and (iii) propose a comprehensive framework for the effect of thermal and mechanical loads on the performance and related performance-based design (e.g., geotechnical and structural) of single and groups of energy piles. The results presented in this thesis suggest the conclusion that (a) the thermo-mechanical behaviour and performance of energy pile groups are critically different from those of single energy piles; (b) thermal loads, applied alone or in conjunction to mechanical loads, represent a serviceability and not an ultimate limit state problem; and (c) no energy pile analysis and design can be considered complete without addressing the behaviour of piles as both isolated elements and in a group.

EPFL2018

Thermo-mechanical performance of energy pile groups

Alessandro Francesco Rotta Loria

EPFL2018