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Development of a predictive framework for geothermal and geotechnical responses
in cold regions experiencing climate change
Développement d'un cadre conceptuel pour les réponses géotechniques et géothermales dans une
zone polaire sous l'influence du changement climatique
Nishimura S.
Hokkaido University
Jardine R.J., Fenton C.H.
Imperial College London
Olivilla S., Gens A.
Universitat Politécnico de Catalunya
Martin C.J.
BP Exploration Operating Company Limited
ABSTRACT: Cold regions, which are expected to suffer particularly severe future climate effects, will pose very challenging
geotechnical conditions in the 21st century involving ground freezing and thawing. Given the uncertainty of future environmental
changes and the vast expanses of the cold regions, it is appropriate to address problems such as pipeline or road construction with
analytical methods that have multiple scales and layers. High- and middle-level predictive tools are described that integrate climatic
predictions from AOGCMs and their down-scaling schemes, geological and topographical (DEM) information, remotely-sensed
vegetation data and non-linear finite element analysis for soil freezing and thawing. These tools output broad scale predictions of
geothermal responses, at a regional scale, that offer hazard zoning schemes related to permafrost thawing. A more intensive local-
scale predictive tool is then outlined that considers fully-coupled thermo-hydro-mechanical processes occurring at the soil-element
level and outputs detailed predictions for temperature changes, pore water behaviour, ground stresses and deformation in and around
geotechnical structures. Applications of these tools to specific problems set in Eastern Siberia and pipeline heave tests are illustrated.
RÉSUMÉ : Les conditions géotechniques des régions polaires représentent un défi pour le future car ces dernières sont plus
susceptibles aux effets du réchauffement climatique, tels que les cycles de gel-dégel. Etant donné les incertitudes existantes
concernant les futures variations climatiques ainsi que l'étendue des zones concernées, l'utilisation de méthodes analytiques
multicouches est requise pour étudier les problèmes liés aux infrastructures linéaires. Cet article décrit un outil de prévision de haut
niveau qui intègre : les prévisions climatiques des AOGCMs, des informations sur la géologie et la topographie (DEM) du terrain, des
données sur la couverture végétale obtenues par télédétection et enfin des analyses par éléments finis des cycles de gel-dégel. Cet outil
prédit approximativement la réponse géothermique à l'échelle régionale, et découpe la zone étudiée en fonction du risque de dégel du
permagel. Un outil plus précis basé sur l'échelle locale est ensuite présenté. Il inclut un modèle avec couplage thermo-hydro-
mécanique et prédit plus en détails les changements de température, les variations de pressions interstitielles et de contraintes ainsi
que les déformations à l'intérieur et autour de structures géotechniques. Des applications pratiques de ces outils sont aussi présentées.
KEYWORDS: Climate change, permafrost, geothermal analysis, THM-analysis
1 INTRODUCTION
Anthropogenic climate change is expected to impact most
severely in cold regions where the ground is currently frozen.
Marked air warming may produce undesirable engineering
consequences, including permafrost degradation over large
areas where rich natural resources are being developed.
Infrastructure design in such regions needs to consider how to
cope with change through rational approaches that couple
climatic, environmental, geotechnical, geological and structural
modelling. Scale is a key problem in establishing such links.
The powerful earth science predictive Atmosphere Ocean
General Circulation Models (AOGCM) work at a much higher
level, and over much broader areas, with consequently less
spatial resolution than conventional geotechnical analyses.
Moreover, the latter need to be relatively sophisticated to give
realistic results. It appears infeasible to combine the two
approaches directly in any monolithic, unified analysis package.
The present study considered three different scales,
cascading predictions from the higher level analyses down as
boundary conditions for each underlying tier. The highest-level
involves manipulating data from AOGCM outputs, applying
statistical and locally informed down-scaling techniques to
produce regional climate change predictions. The middle-level
starts with engineering geological ground modelling, classifying
regions into broad stereotypes informed by local and remote
sensing data. Regional climatic predictions are applied to this by
using broad scale geothermal analyses to consider thermal
changes through potentially great thicknesses of ground,
accounting for background geothermal flux, local geology and
topography. Annually varying thermal profiles and predictions
of permafrost state emerge as inputs to smaller scale fully-
coupled Thermo-Hydro-Mechanical (THM) analyses that
predict engineering outcomes as ground displacement and/or
stress responses to climate change. Such tools allow alternative
infrastructure designs and mitigation measures to be assessed so
that the most rational development strategies may be adopted.
The research described in this paper was part of a BP funded
project to assess cold region climate change impacts. The initial
focus was on Eastern Siberia. An interim overview and
summary of approach was published by Clarke et al. (2008)
while the detailed analytical treatments were set out by
Nishimura et al. (2009a and b). This paper provides an updated
summary of the project’s outputs.
