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Thermal performance of cast-in-place piles with artificial ground freezing in permafrost regions

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Journal of Mountain Science 2024年第4期21卷 1307-1328页

作者： WANG Xinbin CHEN Kun YU Qihao GUO Lei YOU Yanhui JIN Mingyang State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

During the construction of cast-in-place piles in warm permafrost,the heat carried by concrete and the cement hydration reaction can cause strong thermal disturbance to the surrounding *** the bearing capacity of the pile is quite small before the full freeze-back,the quick refreezing of the native soils surrounding the cast-in-place pile has become the focus of the infrastructure construction in *** solve this problem,this paper innovatively puts forward the application of the artificial ground freezing(AGF)method at the end of the curing period of cast-in-place piles in permafrost.A field test on the AGF was conducted at the Beiluhe Observation and Research Station of Frozen Soil Engineering and Environment(34°51.2'N,92°56.4'E)in the Qinghai Tibet Plateau(QTP),and then a 3-D numerical model was established to investigate the thermal performance of piles using AGF under different engineering ***,the long-term thermal performance of piles after the completion of AGF under different conditions was *** experiment results demonstrate that AGF is an effective method to reduce the refreezing time of the soil surrounding the piles constructed in permafrost terrain,with the ability to reduce the pile-soil interface temperatures to below the natural ground temperature within 3 *** results further prove that AGF still has a good cooling effect even under unfavorable engineering conditions such as high pouring temperature,large pile diameter,and large pile ***,the application of this method is meaningful to save the subsequent latency time and solve the problem of thermal disturbance in pile construction in *** research results are highly relevant for the spread of AGF technology and the rapid building of pile foundations in permafrost.

关键词： Permafrost engineering Cast-in-place pile artificial ground freezing Thermal performance.

Influence of freeze tube deviation on the development of frozen wall during long cross-passage construction

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Research in Cold and Arid Regions 2022年第4期14卷 250-257页

作者： JunHao Chen JianLin Wang LeXiao Wang Han Li MeiLin Chen School of Civil Engineering Fujian University of TechnologyFuzhouFujian350118China Key Laboratory of Underground Engineering Fujian Province UniversityFuzhouFujian350118China

This paper investigates the influence of the deviation in freeze pipe installation on the development of the frozen wall in long cross passages by numerical simulation with ANSYS *** study case is from the artificial ground freezing project along the Fuzhou Metro Line 2 between Ziyang Station and Wuliting *** freezepipe configurations,i.e.,one with perfectly aligned pipes without any deviation from design and another with randomly distributed deviation,are included for *** effect of the random deviation in the freeze pipes on frozen wall interconnection time,the thickness of the frozen wall and the development of the temperature field is *** the characteristic section of the numerical model at a depth of 25 m,it is found that the frozen wall interconnection time under the random deviation case and no deviation case is 24 days and 18 days,*** difference in the thickness of the thinnest frozen wall segment between the random deviation and no deviation cases is the largest in the early freezing stage(up to 0.75 m),which decreases with time to 0.31 m in the late freezing *** effects of random deviation are more significant in the early freezing stage and diminish as the freezing time increases.

关键词： Long cross passages artificial ground freezing Random deflection Numerical simulation

artificially frozen ground and related engineering technology in Japan

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Research in Cold and Arid Regions 2021年第2期13卷 77-86页

作者： Satoshi Akagawa Cryosphere Engineering Laboratory TokyoJapan

Since the 1970's, frozen ground has been developing near the Tokyo Bay area around liquefied natural gas(LNG) inground storage tanks. For disaster prevention purposes, the tanks are constructed below the ground surface. Since the temperature of the liquid stored in the tanks is -162℃ the soil surrounding the tanks freezes. Since this frozen ground has existed for almost half a century, we have permafrost near Tokyo. The development of artificial frozen ground may cause frost heaving, resulting in frost heave forces that may cause structural damage of adjacent LNG in-ground storage ***, the demand for frozen ground engineering increased and consequently we now have advanced technology in this area. Fortunately, we use this engineering technology and artificial ground freezing for civil engineering, especially in big and crowded cities like Tokyo. This paper provides a summary of the testing apparatus, test methods, and assessment methods for frost heaving.

关键词： artificial ground freezing frost heave frozen ground engineering

Analytic computation on the forcible thawing temperature field formed by a single heat transfer pipe with unsteady outer surface temperature

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Journal of Coal Science & Engineering(China) 2012年第1期18卷 18-24页

作者： Chi Zhang Wei-hao Yang Jia-gen Qi Tao Zhang State Key Laboratory for Geomechanics & Deep Underground Engineering China University of Mining & Technology Xuzhou China Zhongtianhechuang Energy Corporation Limited Ordos China School of Civil Engineering Yancheng Institute of Technology Yancheng China

A comprehensive and systematic research on the forcible thawing temperature field formed by a single heat transfer pipe with unsteady outer surface temperature was carried out by analytic computation according to the theory of similitude. The distribution law of thawing temperature field, calculation formulas of thawing radius b, heat flux density q and average thawing temperature T were obtained. It theoretically explains that the main influential factors of thawing radius b, heat flux density q and thawing average temperature T are K,f, Lx and co（l）, but Lc affects little. Finally, based on the forcible thawing project of Hulusu air shaft lining, the field data indicate that the analytical formulas of this article are comparatively accurate.

关键词： analytic computation forcible thawing temperature field theory of similitude artificial ground freezing

Revision of thickness design of cylindrical frozen walls considering frost heave

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Research in Cold and Arid Regions 2013年第5期5卷 591-595页

作者： XiaoMin Zhou AnBao Wang HuaDong Guan University of Science and Technology Beijing

This paper outlines development of the thickness design of cylindrical frozen walls in artificial ground freezing （AFG）. A plain strain mechanical model coupled with infinite surrounding soil and rock takes into account the frost heave ratio to investigate the influence of frost heave on the thickness design of frozen wall, and superposition method is used to solve the complicated problem of frozen wall swelling. A revised formula referred to as ＂Baoshen＂ formula has been proposed. This formula provides a convenient analytic solution for any AGF problem involving not only frost heave but also the action of surrounding soil.

关键词： artificial ground freezing frost heave frozen wall

Study on the freezing–thawing deformation of consolidated soils under high pressure

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Research in Cold and Arid Regions 2017年第1期9卷 29-37页

作者： DaYan Wang Wei Ma lele lei LeLe LeiState Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China

The freezing-thawing deformation behaviors of consolidated soils under high pressure have been investigated in a high-pressure-low-temperature （HPLT） Kq consolidation apparatus with a small strain sensor. The tests cover a variety of frozen soil temperatures ranging from -2℃ to -10 ℃, and a series of applied pressures ranging from 1 MPa to 5 MPa. The test results show that, for the consolidated soils under high pressure, their freezing-thawing deformation was caused by the realignment and the deformation of soil particles, the phase change of water, and the water redistribution in the soil. As for the deformation produced by thermal expansion and contraction,it is about 0.04-0.05 mm, accounting for only about 7%~9% of the total deformation. Taking the freezing-thawing deformation produced by temperature disturbance as a creep deformation, the creep models of the developing soil deformation will be determined by the soil＇s final temperature, i.e., the desired temperature. For the soils under a desired temperature between -2℃ and -5℃, the freezing-thawing de-formation develops according to a non-attenuation creep model; but for the soils with a desired temperature lower than -5℃, a full attenuation creep model is followed. The applied pressure and soil type also have a significant influence on the maximum freezing deformation. Generally, the greater the desired pressure applied, the less the maximum deformation is; and the loess freezing deformation is larger than that of sand.

关键词： freezing-thawing deformation artificial ground freezing K0 consolidation high pressure

Average temperature calculation for straight single-row-piped frozen soil wall

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Research in Cold and Arid Regions 2011年第2期3卷 124-131页

作者： XiangDong Hu SiYuan She RuiZhi Yu Department of Geotechnical Engineering Tongji University Shanghai 200092 China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University Shanghai 200092China

The average temperature of frozen soil wall is an essential parameter in the process of design, construction, and safety manage- ment of artificial ground freezing engineering. It is the basis of calculating frozen soil＇s mechanical parameters, fiarther prediction of bearing capacity and, ultimately, safety evaluation of the frozen soil wall. Regarding the average temperature of sin- gle-row-piped frozen soil wall, this paper summarizes several current calculation methods and their shortcomings. Furthermore, on the basis of Bakholdin＇s analytical solution for the temperature field under straight single-row-piped freezing, two new calcula- tion models, namely, the equivalent trapezoid model and the equivalent triangle model, are proposed. These two approaches are used to calculate the average temperature of a certain cross section which indicates the condition of the whole frozen soil wall. Considering the possible parameter range according to the freezing pipe layout that might be applied in actual construction, this paper compares the average temperatures of frozen soil walls obtained by the equivalent trapezoid method and the equivalent tri- angle method with that obtained by numerical integration of Bakholdin＇s analytical solution. The results show that the discrepancies are extremely small and these two new approaches are better than currently prevailing methods. However, the equivalent triangle method boasts higher accuracy and a simpler formula compared with the equivalent trapezoid method.

关键词： artificial ground freezing single-row-piped freezing frozen soil wall average temperature equivalent trapezoid method equivalent triangle method Bakholdin's solution

Nonlinear Analysis on Space-time Expending of artificial Frozen Wall for Supporting Deep Foundation Pit

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Nonlinear Analysis on Space-time Expending of Artificial Fro...