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1.
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 testsare 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. 相似文献
2.
This article attempts to investigate the measure effect of rubble roadbed engineering in permafrost regions of Qinghai-Tibet Plateau. As a case study, Chaidaer-Muli Railway is used to evaluate the measure effect of rubble roadbed engineering in permafrost regions. The AHP(Analytic Hierarchy Process) method is thus employed to establish the evaluation indicator system. The evaluation factor is selected by analyzing the mutual relation between the permafrost environment and roadbed engineering. Thus, a hierarchical structure model is established based on the selected evaluation indices. Each factor is weighted to determine the status in the evaluation system, and grading standards are built for providing a basis for the evaluation. Then, the fuzzy mathematical method is introduced to evaluate the measure effect of rubble roadbed engineering in permafrost regions along the Chadaer-Muli Railway. Results show that most of the permafrost roadbed is in a preferable condition(b) along the Chaidaer-Muli Railway due to rubble engineering measures. This proportion reaches to 86.1%. The proportion in good(a), general(c) and poor states(d) are 0.0%, 7.5% and 6.4%, respectively, in all the evaluation sections along the Chaidaer-Muli Railway. Ground-temperature monitoring results are generally consistent with AHP-FUZZY evaluation results. This means that the AHP-FUZZY method can be applied to evaluate the effect of rubble roadbed engineering measures in permafrost regions. The effect evaluation of engineering measures will provide timely and effective feedback information for further engineering design. The series of engineering measures will more effectively protect permafrost stability. 相似文献
3.
The unfrozen water content and ice content of frozen soil change continuously with varying temperatures, resulting in the temperature dependence of mechanical properties of frozen soil. Thus the dynamic behavior of embankment in permafrost regions under train loading also alters with seasons. Based on a series of strong-motion tests that were carried out on the traditional embankment of Qinghai-Tibet Railway(QTR) in permafrost regions, the acceleration waveforms recorded at the embankment shoulder and slope toes were obtained. Testing results show an obvious attenuation effect on the vertical train loading from road shoulder to slope toes. Furthermore, numerical simulations of a traditional embankment under vertical train loading in different seasons were conducted, and the dynamic behavior of the embankment was described. The results show that the vibration attenuation in the cold season is greater than that in the warm season. The maximum acceleration of vibration drops to about 5% when the train vibration load is transferred through the embankment into the permafrost, and the high-frequency components are absorbed when the vibration transmits downward. Moreover, the dynamic stress under the dynamic train loading decreases exponentially with an increasing depth in different seasons. The results can be a reference for design and maintenance of embankments in permafrost regions. 相似文献
4.
After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission(QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons,while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change. 相似文献
5.
Daniel Nichols 《寒旱区科学》2014,6(4):0361-0371
Alaska has many construction design challenges due to permafrost. Due to either climate changes or human activities and development, permafrost often becomes unstable. Unstable soils can cause thaw settlement, frost jacking, or heaving. These can cause damage to infrastructure, increase maintenance costs, and decrease the life of construction projects. Kotzebue, Alaska, a remote village in the northwest arctic part of Alaska, is ideal for observing such permafrost effects on infrastructure. Three case studies of Kotzebue construction projects are reviewed here： the Front Loop Water Main Extension, which shows the importance of both passive and active freeze thaw protection for water service pipes and how to minimize differential movement between pipes and buildings; the Wastewater Lift Station Replacement, which describes methods for reducing thaw settlement in buildings over time when it is not feasible to prevent thaw settlement, and compares the benefits of frozen ground excavation over traditional excavation practices; and the Ted Stevens Way Rehabilitation, which discusses the effectiveness of 2001 best design practices for gravel road construction over tundra and permafrost, identifies their design and construction failures, and proposes future solutions. 相似文献
6.
In the last several decades, the underlying surface conditions on the Qinghai-Tibet Plateau have changed dramatically, causing permafrost degradation due to climate change and human activities. This change severely influenced the cold regions environment and engineering infrastructure built above permafrost. Permafrost is a product of the interaction between the atmosphere and the ground. The formation and change of permafrost are determined by the energy exchange between earth and atmosphere system. Fieldwork was performed in order to learn how land surface change influenced the thermal regime in permafrost regions. In this article, the field data observed in the Fenghuo Mountain regions was used to analyze the thermal conditions under different underlying surfaces on the Qinghai-Tibet Plateau. Results show that underlying surface change may alter the primary energy balance and the thermal conditions of permafrost. The thermal flux in the permafrost regions is also changed, resulting in rising upper soil temperature and thickening active layer. Vegetation could prevent solar radiation from entering the ground, cooling the ground in the warm season. Also, vegetation has heat insulation and heat preservation functions related to the ground surface and may keep the permafrost stable. Plots covered with black plastic film have higher temperatures compared with plots covered by natural vegetation. The reason is that black plastic film has a low albedo, which could increase the absorbed solar radiation, and also decrease evapotranspiration. The ＂greenhouse effect＂ of transparent plastic film might effectively reduce the emission of long-wave radiation from the surface, decreasing heat loss from the earth＇s surface, and prominently increasing ground surface temperature. 相似文献
7.
The aim of this study is to find an optimal design for a distributed hybrid renewable energy system (HRES) for a residential house in the UK. The hybrid system, which consists of wind turbines, PV arrays, a biodiesel generator, batteries and converters, is designed to meet the known dynamic electrical load of the house and make use of renewable energy resources available locally. Hybrid Optimization Model for Electric Renewables (HOMER) software is used for this study. Different combinations of wind turbines, PV arrays, a biodiesel generator and batteries are evaluated and compared using the NPC (Net Present Cost) method to find the optimal solutions. The HRES is modeled, simulated and optimized using HOMER. The results showed that the wind-biodiesel engine-battery system was the best with the lowest NPC (USD 60254) and the lowest COE (Cost of Energy, USD 0.548/kWh) while the second best system added PV arrays. This study gives evidence of the key contribution wind turbines make to HRES due to abundant wind resources in the UK, especially in Wales. 相似文献
8.
Ground temperatures from four of the seven extensively studied highway cross-sections near Gulkana/Glennallen,Alaska during 1954~1962,were chosen to better understand the impacts of highway construction on warm permafrost.Both the thawing of permafrost and seasonal frost action impacted on road surface stability for about 6 years until the maximum summer thaw reached about 3 m in depth.Seasonal frost action caused most of the ensuing stability problems.Unusually warm summers and the lengths of time required to re-freeze the active layer were far more important than the average annual air temperatures in determining the temperatures of the underlying shallow permafrost,or the development of taliks.The hypothesized climate warming would slightly and gradually deepen the active layer and the developed under-lying talik,but its effect would be obscured by unusually warm summers,by warmer than usual winters,and by the vari-able lengths of time of the zero curtains.At least one period of climate mini-cooling in the deeper permafrost during the early 20th century was noted. 相似文献
9.
兰新高铁大风区风况特征及防风工程设计分区 总被引：1，自引：1，他引：0
兰新高铁是世界上穿越最长风区、防风工程规模最大的铁路。大风严重威胁高铁的运营安全,查明兰新高铁沿线大风分布特征及危害特性极为重要和迫切。利用气候分析、天气诊断及实测校验等方法,结合兰新高铁沿线大风观测资料,找出了微地貌、特定气候导致的局部特大风速区段,确定了沿线大风风速、风向在平面、剖面方向的时空变化规律。基于地形、风力、大风频率及危害程度,将兰新高铁线路划分为五大风区的防风工程设计分区,即：大风极少区、大风低发区、大风一般区、大风易发区和大风频繁区。大风区线路应以降高度、小夹角、大半径为主要选线原则。防风工程的设计,应以大风工程分区为基础,评估不同工程风区环境下的列车安全特性,建立以大风工程分区匹配为主导,适合不同风区,结合设置条件的系统工程对策。 相似文献
10.
11.
The dynamic parameters of permafrost are crucial to and directly affect the accuracy of engineering design and numerical simulation.
This paper describes a new dynamic load direct shear apparatus that was developed to measure these parameters. The power systems
and measurement and control systems of the device are described, as is a successful validation experiment. The results show that this
dynamic load direct shearing device can accurately derive dynamic shear parameters within a certain range of frequencies and amplitudes
of shear load. 相似文献
12.
Cryoplanation Terrace Orientation in Alaska 总被引：2，自引：0，他引：2
Frederick E. Nelson 《Geografiska Annaler: Series A, Physical Geography》1998,80(2):135-151
Exploratory analysis of the orientation of 303 cryoplanation terraces in interior and western Alaska lends tentative support to the hypothesis that these landforms develop through localized erosion related to spatial patterns of snow accumulation and ablation. Cryoplanation terraces exhibit orientation patterns similar to those of cirques in several regions of Alaska. In climatically continental east-central Alaska, cryoplanation terraces are developed preferentially on north-facing slopes and the frequency distribution of terrace orientation is similar to but less concentrated than that of glacial cirques. In south-central Alaska, both cirques and terraces have bimodal frequency distributions corresponding to generalized wind patterns that predominated during Pleistocene glaciations. In western Alaska, terraces and cirques have relatively diffuse patterns without preferred orientation. No clear relation is apparent between the orientation of cryoplanation terraces and their size or elevation, although this may be an artifact of the current inability to differentiate terraces by age. Data from the Eagle Summit/Mastodon Dome area in interior Alaska indicate a possible relation between snowline elevation and the concentration of terrace orientation. 相似文献
13.
Due to a series of linear projects built along National Highway 214, the second "Permafrost Engineering Corridor" on the Qinghai-Tibet Plateau has formed. In this paper, by overcoming the problems of data decentralization and standard inconsistency, permafrost characteristics and changes along the engineering corridor are systematically summarized based on the survey and monitoring data. The results show that: 1) Being controlled by elevation, the permafrost is distributed in flake discontinuity with mountains as the center along the line. The total length of the road section in permafrost regions is 365 km, of which the total length of the permafrost section of National Highway 214 is 216.7 km, and the total length of the permafrost section of Gong-Yu Expressway is 197.3 km. The mean annual ground temperature (MAGT) is higher than -1.5 °C, and permafrost with MAGT lower than -1.5 °C is only distributed in the sections at Bayan Har Mountain and E'la Mountain. There are obvious differences in the distribution of ground ice in the different sections along the engineering corridor. The sections with high ice content are mainly located in Zuimatan, Duogerong Plain and the top of north and south slope of Bayan Har Mountain. The permafrost thickness is controlled by the ground temperature, and permafrost thickness increases with the decrease of the ground temperature, with the change rate of about 37 m/°C. 2) Local factors (topography, landform, vegetation and lithology) affect the degradation process of permafrost, and then affect the distribution, ground temperature, thickness and ice content of permafrost. Asphalt pavement has greatly changed the heat exchange balance of the original ground, resulting in serious degradation of the permafrost. Due to the influence of roadbed direction trend, the phenomenon of shady-sunny slope is very significant in most sections along the line. The warming range of permafrost under the roadbed is gradually smaller with the increase of depth, so the thawing settlement of the shallow section with high ice-content permafrost is more significant. 相似文献
14.
As one part of the National Highway Network Planning in China, the Qinghai-Tibet Expressway （QTE） from Golmud to Lhasa will be built in the interior of the Qinghai-Tibet Plateau （QTP） across about 630 km of permafrost lands. Due to the problematic interactions between the engineering foundations and permafrost, the frozen-soil roadbed of the QTE will be subjected to the more intense thermal disturbances due to the wider black surface. The design and construction for long-term thermal and mechanical stability will face more severe challenges than those in ordinary highways and railways in the same region. In order to provide scientific support for cold regions engineering practices, the QTE Experimental Demonstration Project （EDP） was constructed in situ in the vicinity of the Beilu＇he Permafrost Station in the interior of the QTP. In this paper, the anticipated problems of the proposed QTE project are enumerated, and the structures of the test sections for QTE EDP are described. Through numerical simulations, it was found that the heat transfer processes occurring in each specific road structure are significantly different. The heat accumulation in the highway embankment is mainly due to the black bituminous pavement, but in the railway embankment with its gravel surfaces, it mainly comes from the side slopes. As a result, the net heat accumulation of the highway embankment is three times higher than that in the railway. In expressway, the heat accumulation is further increased because of the wider pavement so that significantly more heat will be accumulated in the roadbed beneath the centerline area. Thus, the thermal stability of the fro- zen-soil roadbed and the underlying permafrost of the QTE can be seriously threatened without proper engineering measures protection against thawing. Based on research and practical experiences from the operating Qinghai-Tibet Railway （QTR） and the Qinghai-Tibet Highway （QTH）, combined with the predicted characteristics of heat transfer in an expressway embankment, nine kinds of engineering measures for mitigating the thaw settlement of foundation soils through the cooling the roadbed soils were built and are being tested in the EDP. The design of the monitoring system for the EDP and the observed parameters were also described. 相似文献
15.
In order to study the stability of the Qinghai-Tibet Highway embankment at Chumaerhe in the permafrost region of northwest China, the ground temperature and deformation at different depths were monitored under the left and right shoulders of the embankment where thermosyphons were set up only on the left shoulder. Based on the monitored data, characteristics of ground temperature and deformation of the left and right shoulders are analyzed and discussed. The results show that the start time of freezing or thawing of the seasonal active layer was about one to two months later than that of the embankment body itself. The stability of each shoulder was mainly controlled by the settlement of different soil layers,whereasfrost heave of soil had scarcely any effect on the stability of the embankment. For the left shoulder, the settlement was mainly influenced by the seasonal active layer and then by the embankment body itself,due to freeze-thaw cycles which may change the soil properties; however, the permafrost layer remained fairly stable. For the right shoulder, creep of the warm permafrost layer was the main influence factor on its stability, followed by settlement of embankment body itself, and finally settlement of the seasonal active layer. Compared with the deformation of the left shoulder, the permafrost layer under the right shoulder was less stable, which indicates that the thermosyphons had a significantly positive effect on the stability of warm permafrost. 相似文献
16.
Long-term temperature data on a soil layer 3.2 m in thickness have been used in the differentiation of a topographically highly complicated permafrost on the territory of Transbaikalia. It was found that the geographical ranges are most clearly identified from mean annual temperature values. The schematic map displays the areas with the temperatures –4 to–1°C,–1 to 1°C and 1 to 4°C which are in good agreement with the permafrost distribution pattern (continuous and discontinuous permafrost, and permafrost islands). A classification of the thermal conditions of soils is carried out according to the highest mean monthly temperature at all depths. We identified four types which are characterized by the qualitative assessment as warm, moderately warm, cold and very cold. A relevant cartographic model shows the distribution of the thermal regime of soils for a warm season. The dot method was used to provide a clear display of available information on soil temperature, and it was possible to show the existence of small areas of the types of thermal regime and their fragmentation. Current changes in soil temperature were determined for August, which are in good agreement with regional changes in ground air temperature. In either case, we observed positive linear trends. Assessments of thermal resources of the soil layer and their geographical patterns belonging to the widespread depression-valley and valley natural systems as well as to the relatively planate surfaces of Transbaikalia can be used for scientific and practical purposes. 相似文献
17.
The Colville basin drains the North Slope of Alaska and is one of several large Arctic river systems located within permafrost. The timing and style of fluvial processes in the earth's permafrost regions differ from those occurring in midlatitude settings. Moreover, in comparison to temperate-zone systems, rivers located entirely within permafrost perform most of their work during relatively short periods of time. This paper examines river ice hydrology and the resulting geomorphic processes that occur within the Colville delta, Alaska. Fluvial processes and landform development within the Colville delta occur after the flood-pulse is initiated by the breakup of river ice. During this 4-month period, the geomorphic processes are largely influenced by the movement of ice. The flood-pulse and accompanying river ice influences erosional and depositional processes and results in unique styles of sediment transport, deposition, and riverbank erosion. 相似文献
18.
基于MK检验、滑动t检验、EOF分析方法,使用近50年（1961-2012年）黑龙江省32个气象基准台站逐日冻土观测数据、气温观测数据,对黑龙江省冻土厚度时空变化特征进行了分析。结果表明：① 近50年黑龙江省冻土厚度减少了12.86 cm,下降速率为-0.53 cm/a,以2001年为界发生了突变。② 冻土厚度空间分布呈现由北厚南薄格局,中部地区冻土厚度较同纬度其他区域偏低;空间变化呈现南部冻土厚度降低快,北部降低慢,中部与西部、东南部呈相反变化的特征,伊春、铁力、漠河观测点为冻土变化敏感区。③ 气温是影响黑龙江省冻土厚度变化的主要因素,与冻土厚度相关系数为-0.611。本文的主要贡献为揭示了黑龙江省冻土厚度的空间变化特征,为相关研究及各级政府规划提供了依据。 相似文献
19.
Oil wells on the North Slope of Alaska pass through deep deposits of permafrost. The heat transferred during their operation causes localized thawing, resulting in ground subsidence adjacent to the well casings. This subsidence has a damaging effect, causing the casings to compress, deform, and potentially fail. This paper presents the results of a laboratory study of the thaw consolidation strain of deep permafrost and its predictive modeling. Tests were performed to determine strains due to thaw and post-thaw loading, as well as soil index properties. Results, together with data from an earlier testing program, were used to produce empirical models for predicting strains and ground subsidence. Four distinct strain cases were analyzed with three models by multiple regression analyses, and the best-fitting model was selected for each case. Models were further compared in a ground subsidence prediction using a shared subsurface profile. Laboratory results indicate that strains due to thaw and post-thaw testing in deep core permafrost are insensitive to depth and are more strongly influenced by stress redistributions and the presence of ice lenses and inclusions. Modeling results show that the most statistically valid and useful models were those constructed using moisture content, porosity, and degree of saturation. The applicability of these models was validated by comparison with results from Finite Element modeling. 相似文献
20.
In order to systemically summarize and integrate technology of highway construction in permafrost regions on the Qinghai-Tibet Plateau,we studied disciplines and mechanisms of formation and development of problems and challenges in highway engineer-ing in high-altitude permafrost regions based on construction experiences for 50 years and on 30 years of research regarding the Qinghai-Tibet and Xikang highways.Embankments,pavements,bridges,and countermeasures for ecosystem protection in per-mafrost regions were the main study objects.We combined extensive analysis of key problems of engineering stability with inter-action between permafrost and highways,theoretical models,indoor tests,and field tests to reveal the interaction between em-bankments,pavements,bridge piles,and permafrost.In this paper,we propose a series of engineering measures for highway sta-bility,design parameters,key indexes for pavement durability in low temperature,relationships between re-freezing time of bridge-pile foundation and strength development as well as ecosystem recovery in high-latitude cold regions;these eventually form a construction technology package for permafrost regions. 相似文献