Ultimate bearing capacity of energy piles in dry and saturated sand

Liu, Hanlong; Wang, Chenglong; Kong, Gangqiang; Bouazza, Abdelmalek

doi:10.1007/s11440-018-0661-6

Cited by 62 publications

(18 citation statements)

References 29 publications

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“…At a given matric suction, the trend of pile resistance with temperature conforms to some existing experimental data and contradicts with others. From the current study, results regarding silt soil at a higher matric suction agree with the trend observed by Wang et al [8], however, it contradicts with the trend noted in Liu et al [6], Kramer and Basu [18], Goode and McCartney [20], and Ng et al [5]. On the other hand, the trend of pile resistance at a relatively low suction range of silt and throughout the range of clay soil agrees with those above studies.…”

Section: Resultssupporting

confidence: 53%

“…For energy geo-structures (e.g., energy piles, heat exchangers, multipurpose piles), experimental evidence exists that the pile performance is affected by elevated temperatures [4][5][6]. In geothermal applications involving piles, temperatures can often exceed 50 °C [6][7]. Consequently, a variation of ultimate pile resistance was observed under higher temperatures.…”

Section: Introductionmentioning

confidence: 99%

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A model for ultimate bearing capacity of piles in unsaturated soils under elevated temperatures

Thota

Vahedifard

2020

E3S Web Conf.

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Geo-energy applications such as energy piles can expose unsaturated, deep foundation soils to elevated temperatures. This paper presents a closed-form equation for the ultimate bearing capacity of piles in unsaturated soils subject to elevated temperatures under drained conditions. For this purpose, a temperature-dependent effective stress model was incorporated into calculations of skin resistance and end bearing resistance of piles. The proposed temperature-dependent model is an extension of the modified β method for determining the ultimate pile bearing capacity of unsaturated soils under drained conditions. Employing the proposed model, a parametric study was carried out to evaluate the ultimate pile bearing capacity for hypothetical clay and silt soils at temperatures ranging from 25 °C to 55 °C. For both clay and silt, the results indicated that the ultimate pile bearing capacity varies with an increase in temperature. Different trends with temperature were observed for clay and silt. A monotonic increase in pile resistance was observed in clays. For silt, the pile resistance increased at relatively low matric suction whereas it decreased at higher matric suctions.

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Section: Resultssupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

A model for ultimate bearing capacity of piles in unsaturated soils under elevated temperatures

Thota

Vahedifard

2020

E3S Web Conf.

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“…At present, most studies are limited to the indoor model test [12][13][14] and numerical simulation [15,16], and the field test study of energy piles is scarce. The spiral-shaped pipe is characterized by a large heat transfer range and high heat transfer efficiency.…”

Section: Introductionmentioning

confidence: 99%

Study on the thermal response of spiral energy piles based on field test

et al. 2023

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Field tests of spiral energy piles under the combined effect of temperature and loading are relatively few. Based on the field test, the heat transfer efficiency, pile strain, axial force and shaft friction of two spiral energy piles were studied. The major findings of the experimental studies were as follows: First, when the double spiral energy pile was heated, the temperature distribution was more uniform; the total heat transfer and the heat transfer rate were higher than those of the single spiral energy pile. Second, the pile strain distribution was such that smaller values were noticed at both pile ends while larger values were in the middle part of the pile. The additional tensile stresses of the two piles generated during cooling reached 4.06 MPa and 4.75 MPa, which exceeded the tensile strength of concrete. Finally, during heating, the shaft friction was negative in the middle and upper pile and positive in the middle and lower pile. The single spiral energy pile showed two neutral points. The downward load generated by the single spiral energy pile was about 885 kN higher than that generated by the double one. The above changes should be focused on in the actual project.

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“…Hence, compared with BHE, an energy pile can provide a higher heat transfer capacity [6,7]. Moreover, in the past few decades, considerable efforts have been focused on energy piles through full-scale tests [3,8], model tests [9,10] and numerical modeling [11,12].…”

Section: Introductionmentioning

confidence: 99%

A Finite Element Model for Investigating Unsteady-State Temperature Distribution and Thermomechanical Behavior of Underground Energy Piles

Zhao

et al. 2022

Applied Sciences

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The underground energy geostructure represented by the energy pile is one of the key paths for the cooperative development of underground space and geothermal energy. Because of its advantages of low cost, high efficiency and no extra occupation of underground space, it has become a feasible alternative to the borehole heat exchanger. The change in the temperature field of the energy pile and its surrounding ground not only affects the geological environment but also influences the thermomechanical performance and the durability of the structure. However, the temporal and spatial unsteady-state temperature distribution of piles and surrounding rock under typical intermittent and unbalanced thermal load conditions is still unclear. In this paper, a finite element model was applied to analyze the unsteady-state temperature distribution, and the thermomechanical behavior of the energy pile group was developed and verified. The temperature field distribution of pile and surrounding rock under typical intermittent working and unbalanced thermal load conditions were determined. Moreover, the thermomechanical behavior characteristics of the energy pile group were investigated. Finally, the influences of pile layout on the thermomechanical behavior of the energy pile group were identified by designing six different scenarios. The results indicate that under typical intermittent operation conditions, the temperature of the energy pile and surrounding ground near the heat exchange pipe varies periodically. For areas with unbalanced cooling and heating loads, long-term operation of energy piles leads to thermal accumulation, and the maximum temperature of energy piles occurs in the first daily cycle. In summer/winter working conditions, the increase/decrease in pile temperature induces axial compression/tensile stress. When the pile group is partially used as the energy pile, the non-energy pile acts as the “anchor pile”, and it generates the added tensile stress.

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Ultimate bearing capacity of energy piles in dry and saturated sand

Cited by 62 publications

References 29 publications

A model for ultimate bearing capacity of piles in unsaturated soils under elevated temperatures

A model for ultimate bearing capacity of piles in unsaturated soils under elevated temperatures

Study on the thermal response of spiral energy piles based on field test

A Finite Element Model for Investigating Unsteady-State Temperature Distribution and Thermomechanical Behavior of Underground Energy Piles

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