Thermomechanical properties of an energy micro pile-raft foundation in silty clay

Kong, Gangqiang; Cao, T.J.; Hao, Yao-hu; Zhou, Yang; Ren, Lianwei

doi:10.1016/j.undsp.2019.09.005

Cited by 21 publications

(9 citation statements)

References 23 publications

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“…The Authors presented nine possible technical solutions along with construction details and recommendations for the application of EMPs to existing buildings. Kong et al [21] presented a first EMP installation in China where an existing piled raft foundation on silty clay was underpinned with 8 micro-piles, two of which equipped with heat exchangers. Results showed that the EMP-raft foundation could provide adequate heat exchange compared with other types of ground heat exchangers.…”

Section: 12)mentioning

confidence: 99%

“…Also, a number of pilot field applications has been implemented in Europe in the last two decades. Significant examples include the foundations of terminal E of Zurich airport (CH), with a total of 315 thermo-active piles out of 440 [20]; the foundations of Lambeth College in London (UK), with 143 EPs [4]; and the World Expo Axis building in Shanghai (China), with approximately 6000 EPs [21].…”

Section: Introductionmentioning

confidence: 99%

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Energy performance assessment of thermo-active micro-piles via numerical modeling and statistical analysis

Cecinato

Salciarini

2022

Geomechanics for Energy and the Environment

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Energy micro-piles (EMPs) constitute a promising emerging technology, able to provide both energy and structural retrofitting to existing buildings. Although a number of studies have been published on the energy performance of standard energy piles (EPs), bespoke analysis is required for EMPs due to their different geometry and peculiar design and site constraints. In this work, a parametric study is carried out by means of numerical Finite Element simulations complemented by statistical analysis, aimed at identifying the dominant parameters in maximizing EMP thermal efficiency. Two categories of parameters, namely design-dependent and site-dependent ones, are separately considered to provide guidance for practitioners on both detailed geothermal sizing and overall feasibility assessment. The parameter space is efficiently explored resorting to Taguchi Experimental Design statistical tools. Results show that different design criteria to those for EPs should be used for EMPs. Notably for the latter, contrary to the former, the diameter of heat exchanger pipes emerges as one of the most important factors promoting thermal efficiency, while being the single easiest parameter to engineer. On the other hand, while maximizing the number of U-pipes and pile diameter is crucial for EPs, it does not impact the energy performance of EMPs, due to geometry constraints and the expected occurrence of thermal interferences. Among site-dependent factors, a large ground thermal conductivity is confirmed as an important feature to ensure a high energy performance, while interesting insights are obtained about the role of basement thermal insulation in the long-term EMP thermal output.

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Section: 12)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Energy performance assessment of thermo-active micro-piles via numerical modeling and statistical analysis

Cecinato

Salciarini

2022

Geomechanics for Energy and the Environment

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“…Although considerable research has been undertaken to develop a better understanding of the mechanisms of behavior of TA piles to provide assurance regarding the efficacy and safety of the application in SGE systems [11][12][13][14], only a few studies refer specifically to micropiles [15,16]. Indeed, of 26 field tests reviewed, just 9 involved TA micropiles [17][18][19][20][21][22][23][24][25]. Of these studies, the thermo-mechanical response of TA micropiles was only reported by [17] (bored), and [24,25] (driven), and in all three cases, the piles were installed in fine-grained soils.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, of 26 field tests reviewed, just 9 involved TA micropiles [17][18][19][20][21][22][23][24][25]. Of these studies, the thermo-mechanical response of TA micropiles was only reported by [17] (bored), and [24,25] (driven), and in all three cases, the piles were installed in fine-grained soils. Furthermore, numerical analysis of TA micropiles has been reported by [25][26][27][28] where driven micropiles in fine-grained soils were modeled, and [29] who modeled a bored (wished-in-place) micropile in frictional media.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Study of the Behavior of Micropile Foundations under Cyclic Thermal Loading

Lupattelli,

Bourne-Webb,

Bodas Freitas

et al. 2023

Applied Sciences

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Micropiles are small-diameter foundation elements that are widely used in building refurbishment to reinforce existing foundations or provide new foundations where access for construction is difficult. Thermally-activated (TA) micropiles could be useful as an efficient means of providing cost-effective ground-coupling when shallow geothermal energy systems are considered in building rehabilitation. It is well-established that thermal activation of pile foundations results in thermo-mechanical interactions between the pile and the surrounding soil. These thermally-induced effects need to be examined to ensure that they do not adversely impact the load transfer function of the micropile. Numerical analysis is able to produce reliable predictions of thermo-mechanical behavior of TA piles, and this study applied this technique to examine the cyclic thermal behavior of micropiles, isolated and in groups. For the situations considered in this study, it is shown that during cyclic thermal activation, irrecoverable movements are unlikely to be significant in design terms, if the initial mobilization of the shaft resistance is low. Though stable, cyclic thermal movement amplitudes are large enough that they should be considered in design. The study highlights that large changes in thermal stress can develop and be locked-in to the response of long flexible piles, and that these should be verified in design. Further, as pile spacing reduces, thermal interference results in a loss of heat exchange capacity per pile, which has to be considered in the design of large groups of TA micropiles. Therefore, TA micropiles can offer an efficient and secure means of providing ground coupling in shallow geothermal energy systems.

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“…Foundations are divided into: tape, monolithic, prefabricated, pile, slab, columnar, block [3,4]. Pile [5,6] can be considered as one of the types of foundations that combine good performance and low cost. They are less sensitive to the dynamics of changes in the state of soils, including those caused by groundwater fluctuations.…”

Section: Introductionmentioning

confidence: 99%

An integrated way to improve the properties of soil-cement pile foundations

Серегин

2020

E3S Web Conf.

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The scientific article presents the results of the development of a method for improving the properties of soil-cement pile foundations by the drilling-mixing method using mechanical activation of soil-cement mixture in filler soils. Two methods for improving filler soils are considered. The choice of the mathematical methods for the research is justified. The feasibility of a complex combination of mathematical modeling methods and experimental design to achieve the goal set in this scientific article is substantiated. The physicomechanical characteristics of soil-cement are considered: a measure of brittleness, brittleness coefficient, compressive strength, splitting strength, strength variation coefficient. Based on the research, practical recommendations are given for improving soil-cement pile foundations.

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Thermomechanical properties of an energy micro pile-raft foundation in silty clay

Cited by 21 publications

References 23 publications

Energy performance assessment of thermo-active micro-piles via numerical modeling and statistical analysis

Energy performance assessment of thermo-active micro-piles via numerical modeling and statistical analysis

A Numerical Study of the Behavior of Micropile Foundations under Cyclic Thermal Loading

An integrated way to improve the properties of soil-cement pile foundations

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