Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Understanding the thermo-mechanical behaviour of thermal piles in sand
Thermal piles are piled foundations that can be used both to extract heat at shallow depth from the ground and to transfer load from the structure to the ground. Despite an increased number of applications of thermal piles in recent years, knowledge of the thermo-mechanical behaviour of thermal piles is still limited. The literature reveals that additional thermal loading results in considerable induced axial load and stress along the pile, that can lead to a reduction in safety factor down to 1. Also, there are inconsistencies in the literature regarding the thermo-elastic/plastic, reversible/irreversible response of thermal piles and also on the effects of cyclic thermal loading on the side shear friction at the soil–pile interface. Moreover, the framework proposed in the Thermal Pile Standard (Ground Source Heat Pump Association, 2012) has not been tested for various soils conditions. In this study, the effect of thermo-mechanical loading on the mechanical performance of thermal piles and the soil–pile interface is investigated. A 1g laboratory model was developed using a stainless steel model pile embedded in medium-dense, dry sand. Strain and temperature along the pile were monitored using multiplexed fibre Bragg grating sensors. A 2D finite difference heat transfer model was developed in Matlab, predicting the temperature profiles within the soil. Findings from the numerical model were used to design the location of the temperature sensors in the soil. Laboratory tests were divided into five scenarios, involving both shaft resisting and shaft and base resisting piles. It was found that under thermo-mechanical loading, up to 68.4% of the maximum induced load was transferred to the pile toe for the shaft resisting pile, compared to virtually none under mechanical loading. It was further found that the level of restraint caused by medium-dense sand with a relative density of 57% was rather limited in the absence of surcharge load and the degree of freedom varied between 0.97 and 1.0. Moreover, it was found ...
Understanding the thermo-mechanical behaviour of thermal piles in sand
Thermal piles are piled foundations that can be used both to extract heat at shallow depth from the ground and to transfer load from the structure to the ground. Despite an increased number of applications of thermal piles in recent years, knowledge of the thermo-mechanical behaviour of thermal piles is still limited. The literature reveals that additional thermal loading results in considerable induced axial load and stress along the pile, that can lead to a reduction in safety factor down to 1. Also, there are inconsistencies in the literature regarding the thermo-elastic/plastic, reversible/irreversible response of thermal piles and also on the effects of cyclic thermal loading on the side shear friction at the soil–pile interface. Moreover, the framework proposed in the Thermal Pile Standard (Ground Source Heat Pump Association, 2012) has not been tested for various soils conditions. In this study, the effect of thermo-mechanical loading on the mechanical performance of thermal piles and the soil–pile interface is investigated. A 1g laboratory model was developed using a stainless steel model pile embedded in medium-dense, dry sand. Strain and temperature along the pile were monitored using multiplexed fibre Bragg grating sensors. A 2D finite difference heat transfer model was developed in Matlab, predicting the temperature profiles within the soil. Findings from the numerical model were used to design the location of the temperature sensors in the soil. Laboratory tests were divided into five scenarios, involving both shaft resisting and shaft and base resisting piles. It was found that under thermo-mechanical loading, up to 68.4% of the maximum induced load was transferred to the pile toe for the shaft resisting pile, compared to virtually none under mechanical loading. It was further found that the level of restraint caused by medium-dense sand with a relative density of 57% was rather limited in the absence of surcharge load and the degree of freedom varied between 0.97 and 1.0. Moreover, it was found ...
Understanding the thermo-mechanical behaviour of thermal piles in sand
Rafiei, A (Autor:in) / Arya, C / Fuentes, R
28.03.2017
Doctoral thesis, UCL (University College London).
Hochschulschrift
Elektronische Ressource
Englisch
DDC:
690
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