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Thermal Characteristics of the Embankment with Crushed Rock Side Slope to Mitigate thaw settlement Hazards of the Qinghai-Tibet Railway

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Acta Geologica Sinica(English Edition) 2009年第5期83卷 1000-1007页

作者： LI Guoyu MU Yanhu ZHANG Xia State Key Laboratory of Frozen Soil Engineering CAREERL Chinese Academy of Science Lanzhou 730000 China School of Energy and Power Engineering Lanzhou University of Technology Lanzhou 730050 China

Permafrost （perennially frozen ground） appears widely in the Golmud-Lhasa section of the Qinghai-Tibet railway and is characterized by high ground temperature （≥1℃） and massive ground ice. Under the scenarios of global warming and human activity, the permafrost under the railway will gradually thaw and the massive ground ice will slowly melt, resulting in some thaw settlement hazards, which mainly include longitudinal and lateral cracks, and slope failure. The crushed rock layer has a thermal semiconductor effect under the periodic fluctuation of natural air. It can be used to lower the temperature of the underlying permafrost along the Qinghai-Tibet railway, and mitigate the thaw settlement hazards of the subgrade. In the present paper, the daily and annual changes in the thermal characteristics of the embankment with crushed rock side slope （ECRSS） were quantitatively simulated using the numerical method to study the cooling effect of the crushed rock layer and its mitigative ability. The results showed that the ECRSS absorbed some heat in the daytime in summer, but part of it was released at night, which accounted for approximately 20% of that absorbed. Within a year, it removed more heat from the railway subgrade in winter than that absorbed in summer. It can store approximately 20% of the ＂cold＂ energy in subgrade. Therefore, ECRSS is a better measure to mitigate thaw settlement hazards to the railway.

关键词： Qinghai-Tibet railway climate change embankment with crushed rock side slope,numerical analysis thaw settlement

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Effects of freeze-thaw cycle on engineering properties of loess used as road fills in seasonally frozen ground regions,North China

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Journal of Mountain Science 2017年第2期14卷 356-368页

作者： LI Guo-yu MA Wei MU Yan-hu WANG Fei FAN Shan-zhi WU Ya-hu State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of SciencesLanzhou 730000China

Compacted loess is widely used as fills of road embankments in loess regions of northern ***, densely-compacted loess can satisfy the requirements of embankment strength and postconstruction deformation. However, uneven subsidence, pavement cracks and other related damages can affect the integrity of loess subgrade after several years of operation,and even cause some hazards, especially in North China, where the strong freeze-thaw erosion occurs. In this study, cyclic freeze-thaw tests for both densely and loosely compacted loess samples were performed to determine the variation in engineering properties such as volume, void ratio, collapsible settlement,microstructure, and the related mechanisms were addressed. The experimental results showed that an obvious water migration and redistribution occurred within the samples during freeze-thaw cycles. Ice lenses and fissures could be identified in the upper frozen layers of the samples. After freeze-thaw cycles,the dry densities of the upper layers of samples changed significantly due to strong freeze-thaw erosion. The dry densities decreased for the dense sample and increased for the loose sample. It can be found that dense samples become loose, while loose samples became dense with the increasing number of freeze-thaw cycles. Their related void ratios changed reversely. Both void ratios tended to fall into a certain range, which verified the concept of a residual void ratio proposed by Viklander. The loosening process of densely compacted samples involves the formation of large pores, volume increase and density reduction as well as the related changes in mechanical properties because freeze-thaw cycles may be important contribution to problems of loess road *** effects of freeze-thaw cycles, therefore,should be taken into account in selecting loess parameters for the stability evaluation of road embankment in seasonally frozen ground regions.

关键词： Loess Freeze-thaw cycle Frost heave thaw settlement Road engineering

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Compressibility of fine-grained soils subjected to closed-system freezing and thaw consolidation

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Mining Science and Technology 2009年第5期19卷 631-635页

作者： BOLEY Conrad Institute for Soil Mechanics and Geotechnical Engineering University of the Bundeswehr Munich

In order to investigate the effects of freezing and thawing on the compressibility of fine-grained soils, freezing and thawing tests and subsequent compression tests with fine-grained soils in an oedometer were carried out. During the freezing, a part of the soils is loosened and another part is over-consolidated under the freezing pressure σE. The compression curves after the freezing and thaw consolidation are neither different from the normal consolidation curve nor from the rebound curve of an unfrozen soil, until the consolidation pressure σz = σE is arrived. Based on the experimental results, a theoretical model has been devel- oped to predict the frost heaves, the thaw-settlements and the compressive deformations of fine-grained soils after the thaw consolidation. The theoretical results are very close to the experimental results.

关键词： ice lens frost heave thaw settlement compressibility

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Centrifuge model test on performance of thermosyphon cooled sandbags stabilizing warm oil pipeline buried in permafrost

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Research in Cold and Arid Regions 2021年第3期13卷 234-255页

作者： GuoYu Li HongYuan Jing Nikolay Volkov Wei Ma PengChao Chen State Key Laboratory of Frozen Soil Engineering(SKLFSE) Northwest Institute of Eco-Environment and Resources(NIEER)Chinese Academy of Sciences(CAS)LanzhouGansu 730000China Da Xing'anling Observation and Research Station of Frozen-ground Engineering and Environment NIEERCASJiagedaqiHeilongjiang 165000China PipeChina North Pipeline Company LangfangHebei 065000China GEOINGSERVICE LLP(Fugro Group) 29 Vernadskogo AvenueMoscowRussia

The thaw settlement of pipeline foundation soils in response to the operation of the first China-Russia Crude Oil Pipeline along the eastern flank of the northern Da Xing'anling Mountains in Northeast China was simulated in a physical model test(with a similitude ratio of 1/73) in a geotechnical centrifuge. Two pipes of a supported and an unsupported section were evaluated over a testing period for simulating 20 years of actual pipeline operation with seasonal cyclically changing oil and ambient temperatures. The results show that pipe settlement of the supported pipe was 45% of settlement of the unsupported pipe. settlement for the unsupported section was approximately 35% of the thaw bulb depth below the initial pipe elevation, only 30% of that for the supported pipe due to the influence of the supports. The final thaw bulbs extended approximately 3.6 and 1.6 times of the pipe diameter below the unsupported and supported pipe bottom elevations, respectively. The sandbag supports kept frozen during the test period because of cooling effect of the thermosyphons. The maximum bending stress induced over the 20 m span length from bearing of the full cover over the pipe would be equivalent to40% specified minimum yield strength(SMYS). Potential buckling of the pipe should be considered as the ground *** study also offers important data for calibration and validation of numerical simulation models.

关键词： centrifuge test oil pipeline frost heave thermosyphon thaw settlement permafrost engineering

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Characterization of frozen soil-cement mixture for berm construction in cold regions

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Research in Cold and Arid Regions 2015年第4期7卷 300-306页

作者： HaoLin Yu XinLei Na ZhaoHui Joey Yang Key Lab of Structures and Dynamic Behavior and Control of Ministry of Education School of Civil EngineeringHarbin Institute of Technology Visiting Scholar University of Alaska Anchorage University of Alaska Anchorage

Lagoon berms in western Alaska are difficult to design and build due to limited resources, high cost of construction and materials, and warm permafrost conditions. This paper explores methods to treat locally available frozen materials and use them for berm construction. The goal is to find an optimized mix ratio for cement and additives that can be effective in increasing the strength and decreasing the thaw settlement of an ice-rich frozen silty soil. Soil of similar type and ice content to the permafrost found at a project site in Eek, Alaska is prepared in a cold room. The frozen soil is pulverized and cement, additives and fibers are added to the samples for enhancing shear strength and controlling thaw settlement. thaw settlement and direct shear tests are performed to assess strength and settlement characteristics. This paper presents a sample preparation method, data from thaw settlement and direct shear tests, and analyses of the test results and preliminary conclusions.

关键词： frozen soil stabilization thaw settlement shear strength Portland cement

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Research on Types of Frozen Soil and Design of Yichun to Suihua Section of Hegang-Harbin Highway——From ErguTree Farm to Liberation Bureau

Research on Types of Frozen Soil and Design of Yichun to Sui...

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寒区冰情与冻土水文效应——第4届“寒区水资源及其可持续...

作者： Yang WANG~1,Dianyu ZHANG~1,Yuchun BAI~1,Peng WANG~1,Yangquan OU~2 1 Institute of 904 Engineering Investigation,Heilongjiang Province,Harbin,150027 2 Institute of Heilongjiang Province highway investigations,Heilongjiang Province,Harbin

The project is located at Yichun in the northeast of Heilongjiang *** area belongs to mountain landform and middle low mountains etching *** climate belongs to continental monsoon climate and the change of four seasons is *** formation lithology,the types of frozen soil,the engineering geology condition and distributing situation of segregated frozen ground are studied by the investigation of frozen soil situation along the highway from Ergu tree farm to Liberation *** sections of layer are mainly pale red granite in Yanshan stage(γ52)and Variscanstage(γ43),the dash diluvia formation in Quaternary system and the slope diluvia formation in Quaternary *** frozen soil along the highway can be divided into two types that the seasonally frozen ground and segregated frozen *** engineering geology condition along the line is mainly roadbed,cultivated field and *** vegetation along the highway are mainly straw,cultivated field,forest(pinaster,birch and,short poling forest).The lithology is mainly embankment earth,decayed powder clay,middle fine sand and *** types of frozen soil are mainly full frozen soil,ice layer containing earth,rich frozen soil and frozen soil with much *** paper provides advices and countermeasures for the improvement of harmful geology condition of frozen soil ***,summary up the attention items of frozen soil construction and design.

关键词： frozen soil seasonally frozen ground segregated frozen ground frost heaving thaw settlement

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