Numerical Investigations on District Heating Pipelines under Combined Axial and Lateral Loading

Research output: Contribution to journalConference articleResearchpeer review

Authors

  • Tim Gerlach
  • Martin Achmus
  • Mauricio Terceros
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Details

Original languageEnglish
Pages (from-to)435-444
Number of pages10
JournalEnergy Procedia
Volume149
Early online date8 Sept 2018
Publication statusPublished - Sept 2018
Event16th International Symposium on District Heating and Cooling, DHC 2018 - Hamburg, Germany
Duration: 9 Sept 201812 Sept 2018

Abstract

Within the design process of district heating networks, the soil resistances in axial and lateral pipeline direction are commonly treated independently as friction resistance and bedding pressure. However, at curved segments or near ellbows, these resistances occur simultaneously and affect each other. The state of knowledge regarding this topic is summarized, and it is shown that only limited information exists for this case of loading. Therefore, a three-dimensional finite element model was developed, using the sophisticated concept of hypoplasticity as an advanced constitutive model for the bedding material. This soil model is able to account for dilatancy, barotropy and pycnotropy of granular soils. Subsequently, variations of the loading direction were performed for a reference system. The investigations give a good insight into the behaviour of district heating pipelines under combined loading, showing the interdependency of skin friction resistance and bedding pressure. We present a design approach which incorporates interaction terms, derived from the presented investigations. Results gained from these investigation are then transferred to the academic district heating network design tool IGtH-Heat, to evaluate in which manner the incorporation of coupling terms between bedding and friction resistance influences the pipe-soil interaction. Additionally, a temperature dependent formulation of maximum friction resistance is adopted to incorporate the effects of radial pipe displacement. Thereby we demonstrate that the predicted pipeline's displacement significantly change when these effects are taken into account. Using this new formulation, model predictions are compared to data from full scale field measurements.

Keywords

    buried pipelines, combined loading, numerical modelling, Soil-structure interaction

ASJC Scopus subject areas

Sustainable Development Goals

Cite this

Numerical Investigations on District Heating Pipelines under Combined Axial and Lateral Loading. / Gerlach, Tim; Achmus, Martin; Terceros, Mauricio.
In: Energy Procedia, Vol. 149, 09.2018, p. 435-444.

Research output: Contribution to journalConference articleResearchpeer review

Gerlach T, Achmus M, Terceros M. Numerical Investigations on District Heating Pipelines under Combined Axial and Lateral Loading. Energy Procedia. 2018 Sept;149:435-444. Epub 2018 Sept 8. doi: 10.1016/j.egypro.2018.08.208, 10.15488/3908
Gerlach, Tim ; Achmus, Martin ; Terceros, Mauricio. / Numerical Investigations on District Heating Pipelines under Combined Axial and Lateral Loading. In: Energy Procedia. 2018 ; Vol. 149. pp. 435-444.
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abstract = "Within the design process of district heating networks, the soil resistances in axial and lateral pipeline direction are commonly treated independently as friction resistance and bedding pressure. However, at curved segments or near ellbows, these resistances occur simultaneously and affect each other. The state of knowledge regarding this topic is summarized, and it is shown that only limited information exists for this case of loading. Therefore, a three-dimensional finite element model was developed, using the sophisticated concept of hypoplasticity as an advanced constitutive model for the bedding material. This soil model is able to account for dilatancy, barotropy and pycnotropy of granular soils. Subsequently, variations of the loading direction were performed for a reference system. The investigations give a good insight into the behaviour of district heating pipelines under combined loading, showing the interdependency of skin friction resistance and bedding pressure. We present a design approach which incorporates interaction terms, derived from the presented investigations. Results gained from these investigation are then transferred to the academic district heating network design tool IGtH-Heat, to evaluate in which manner the incorporation of coupling terms between bedding and friction resistance influences the pipe-soil interaction. Additionally, a temperature dependent formulation of maximum friction resistance is adopted to incorporate the effects of radial pipe displacement. Thereby we demonstrate that the predicted pipeline's displacement significantly change when these effects are taken into account. Using this new formulation, model predictions are compared to data from full scale field measurements.",
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AU - Gerlach, Tim

AU - Achmus, Martin

AU - Terceros, Mauricio

N1 - Funding information: The presented research work was fund ed by the German Federal iM nistry of Economic Affairs and Energy under Grant number 03ET1335B. The support is gratefully acknowledged.

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