Axial Load Transfer Analyses of Energy Piles at a Rock Site

Abstract

An axial load-transfer analysis is presented in this study that incorporates empirical models for 19 estimating the side shear resistance and end bearing capacity in rock along with associated 20 normalized stress-displacement curves. The analysis was calibrated using results field experiments 21 involving monotonic heating of three 15.2 m-long energy piles in sandstone. Analyses of the field 22 experiments indicates that poor cleanout of the excavations led to an end restraint smaller than that 23 expected for a clean excavation in sandstone. Specifically, end bearing parameters representative 24 of cohesionless sand were necessary to match the load-transfer analysis to the field experiment 25 results. Parametric evaluations of the analysis demonstrate the importance of using appropriate 26 rock-or soil-specific empirical models when estimating the side shear resistance and end bearing 27 capacity of energy piles. The end bearing capacity and side shear resistance in rock are greater 28 than in soils, leading to more restraint and greater thermal axial stresses. The stiffer side shear 29 restraint in rock was also found to lead to a less nonlinear distribution in thermal axial stress.

Thermomechanical Responses of Thermally Interacting Field-Scale Energy Piles

“…A number of studies have evaluated the thermal responses of solitary energy piles subjected to monotonic temperatures (e.g. Laloui et al 2006;Bourne-Webb et al 2009;Akrouch et al 2014;Mimouni 2014;Murphy and McCartney 2015;Wang et al 2015;Murphy et al 2015;Sutman et al 2015;Khosravi et al 2016;Adinolfi et al 2018;Anongphouthet al 2018;Rui and Soga 2018;Sung et al 2018;Faizal et al 2019a;Liu et al 2019;Moradshahi et al 2020b) and cyclic temperatures (e.g. Abdelaziz and Ozudogru 2016;Faizal et al 2016;Ng and Gunawan 2016;Suryatriyastuti et al 2016;Faizal et al 2018Faizal et al , 2019bSung et al 2018;Huang et al 2018;Sarma and Saggu 2020;Yang et al 2020).…”