Scott L. Huang

GIS application in mineral resource analysis-A case study of offshore marine placer gold at Nome, Alaska

Geographic information system (GIS) technology has been applied to analyze the offshore marine placer gold deposits at Nome, Alaska. Two geodatabases, namely Integrated Geodatabase (IG) and Regularized 2.5D Geodatabase (R2.5DG), were created to store and integrate digital data sets in heterogeneous formats. The IG served as a data warehouse and used to manage various geological data, such as borehole, bedrock geology, surficial geology, and geochemical data. The R2.5DG was generated based on the IG and could be used for gold resource estimate at any given spatial domain. Information on placer gold deposits can be updated, queried, visualized, and analyzed by making use of these geodatabases. Ore body boundaries, gold distribution, and the resource estimation at various cutoff grades can be calculated in a timely manner. Based on the enhanced GIS architecture, a web-based GIS (http://uaf-db.uaf.edu/website/) was developed to facilitate remote users to access the offshore marine placer gold data. Users can integrate local data sources with remote data sources for query, visualization and analysis via a web browser. The GIS architecture developed in this project can be readily adapted to mineral resource management in other areas of the state.

Alaska's CRREL permafrost tunnel

Abstract The U.S. Army Cold Regions Research and Engineering Laboratory (U.S.A. CRREL) has maintained a tunnel in the permafrost at Fox, Alaska, near Fairbanks, since 1963. Over the years, extensive research has been carried out by CRREL, the University of Alaska and other agencies. Material properties investigated include creep properties of permafrost soil, in-situ sublimation of ground ice in the permafrost, excavation methods and special maintenance of underground excavations in permafrost. The tunnel serves as a unique laboratory to study mining and geotechnical problems in the Arctic.

Movement Due to Heave and Thaw Settlement of a Full-Scale Test Chilled Gas Pipeline Constructed in Fairbanks Alaska

In this paper the authors report the heave and thaw settlement properties of a test chilled gas pipeline. A full-scale field experiment of the chilled gas pipeline system was conducted in Fairbanks Alaska from 1999 to 2005. The length of the test pipeline was 105m and the diameter was 0.9m. The circulated chilled air was –10 o C. One-third of the pipeline was buried in permafrost and the rest of it was placed in non-permafrost. At the end of July 2003, circulation of the chilled air ceased, however, monitoring of the thaw settlement properties of the test pipeline continued until the middle of April, 2005. The results obtained include: 1) As the frost-bulb around the pipeline in non-permafrost section formed, the test pipeline in the non-permafrost section moved upward, resulting in bending of the pipeline at the boundary. 2) In summers, overburden frozen ground of the pipeline became thinner due to the development of active layer above. The pipeline buried in permafrost section moved upward abruptly, fracturing the thinning overburden frozen ground. 3) The phenomenon mentioned 2) occurred successive summer, and the pipeline uplift in permafrost section continued in summers. 4) In relation with 1), the upward movement in non-permafrost section was confirmed by frost heaving of the pipe foundation. 5) Settlement of the test pipeline was also confirmed by thaw settlement of the foundation. 6) During the thawing process, the temperature of the thawing frost bulb became 0 o C at first and then thawed rapidly in summer together with the development of active layer. As a result , settlement of the pipeline happened rapidly in summer. Introduction In the existing natural gas production field in permafrost regions such as West Siberia, gas pipelines float in water or are exposed in ditchs as shown in the photos of Fig.1. However the gas pressure at the present time has dropped considerably comparing to the one in the initial production days. This pressure drop enables the damaged pipeline system to survive. However, those initially buried gas pipelines are now mostly exposed and lost the structural stabilities and security reliability. As for the natural gas pipeline installation in permafrost regions, the buried system has been recommended for security reasons. In order to prevent thawing of the permafrost shown in Fig.1, the gas must be chilled for transportation in permafrost regions.On the other hand, even with the chilled gas pipeline system, miner problems may still happen in limited sections of the pipeline where frost heave damage occurs when the pipeline freezes surrounding soils in non-permafrost section (Talik). Two primary chilled pipeline test experiments are discussed in the literature: the Calgary Frost Heave Facility and the Caen, France experiment. A third chilled pipeline experiment was conducted at the Fairbanks Frost Heave Facility, but the data remains unavailable to the public. The Caen, France chilled pipeline experiment is well documented in public literature by Geotechnical Science Laboratories (1983, 1986a, 1986b, 1988) and Dallimore and Williams (1985). The purposes of the Caen experiment were to investigate differential heave resulting from the abrupt transition between two different lithologic soils (Caen silt and SNEC sand) with varying frost susceptibilities and the associated stresses incurred by the pipeline and the soil mass. Abrupt lithologic transition zones are common in the natural environment such as the transition between active fluvial gravel deposits and silt overbanks deposits.

Frost Heave Induced Pipe Strain of an Experimental Chilled Gas Pipeline

A full-scale chilled gas pipeline experiment was conducted in Fairbanks, Alaska to develop the design criteria for pipeline construction in arctic regions. The test pipeline had a length of 105 m and a diameter of 0.9 m. One-third of the pipeline was located in permafrost and the remaining was in non-permafrost. The monitoring data were collected from December 1999 to January 2005 including both freezing and thawing phases. In the transition zone between frozen and unfrozen soil, the foundation material experienced a vertical movement caused by differential frost heave. The test results indicated that the bending action was the main factor for the circumferential and longitudinal strain distribution in the pipeline. The circumferential strain ranged from about 100 to 500 during freezing. The maximum tensile and maximum compressive strains along the pipeline were approximately located at the edges of the transition zone.

Countermeasures for Bending and Abrupt Uplift of A Full-scale Test Chilled Gas Pipeline Observed at Boundary between Frozen Ground and Talik

In this paper the authors report the vertical bending properties of a test chilled gas pipeline and the countermeasures of the bending. A full-scale field experiment of the chilled gas pipeline system was conducted in Fairbanks, Alaska from 1999 to 2005. The length of the test pipeline was 105m and the diameter was 0.9m. The circulated chilled air was –10 o C. One-third of the pipeline was buried in frozen ground and the rest of it was placed in talik. At the end of July 2003, circulation of the chilled air ceased, however, monitoring of the thaw settlement-related properties of the test pipeline continued until the middle of April 2005. The following results were presented at the 2nd ATC: 1) As the frost-bulb around the pipeline in talik section formed, the test pipeline in the talik section moved upward, resulting in bending of the pipeline at the boundary. 2) In summers, frozen overburden soil of the pipeline became thinner due to thawing of active layer above. The pipeline buried in frozen section moved upward abruptly, fracturing the thinning frozen overburden ground. 3) The phenomenon mentioned in 2) occurred in successive summers, and the pipeline uplift in frozensection continued. 4) In relation with 1), the upward movement in talik section was confirmed by frost heaving of the pipe foundation. In this report the bending behavior of the test pipeline is described and the several methods to deal with the bending are proposed. Introduction In the existing natural gas production fields in permafrost regions such as West Siberia, segments of gas pipelines could become floating in water or exposed in ditches. The inline gas pressure at the time of events might have dropped considerably from the initial production pressure. This pressure drop had enabled the damaged pipeline system to survive. As time progressed, many of those initially buried gas pipelines became exposed and lost the structural stabilities and security reliability. As for the natural gas pipeline installation in permafrost regions, the buried system has been recommended for security reasons. In order to prevent thawing of permafrost, the gas must be chilled for transportation in permafrost regions.On the other hand, even with the chilled gas pipeline system, minor problems can still happen in limited sections of the pipeline where frost heave damage occurs as the pipeline freezes surrounding soils in talik. Two primary chilled pipeline test experiments are discussed in literature: the Calgary Frost Heave Facility and the Caen, France experiment. A third chilled pipeline experiment was conducted at the Fairbanks Frost Heave Facility, but the data remains unavailable to the public. The Caen, France chilled pipeline experiment is well documented in public literature by Geotechnical Science Laboratories (1983, 1986a, 1986b, 1988) and Dallimore and Williams (1985). The purposes of the Caen experiment were to investigate differential heave resulting from the abrupt transition between two different lithologic soils (Caen silt and SNEC sand) with varying frost susceptibilities and the associated stresses incurred by the pipeline and the soil mass. Abrupt lithologic transition zones are common in the natural environment such as the transition between active fluvial gravel deposits and silt overbanks deposits. The Calgary Frost Heave Experiments, described in detail by Slusarchuk et al. (1978) and Foothills (1981), included six separate test sections with each consisting of 12.2-m long, 1.22-m diameter pipe. The experiments were conducted under field conditions within a highly frost susceptible thick glacial-lacustrine deposit with an average ground water table between 2.3m and 2.6m. In 1974 and 1978, total six sections were constructed. In order to propose a design method for pipelines construction in permafrost regions, which prevents the frost heave related engineering concerns, it is necessary to research the interaction of permafrost and burred chilled pipeline. A full-scale

Ground Temperature Variation Induced by a Buried Chilled Gas Pipeline

In order to understand the complex behavior of gas pipelines in arctic regions, a fullscale experimental pipeline was constructed near Falrbanks, Alaska in December 1999. The pipeline was laid 1.8 m below the ground surface and covered with 0.9 m thick silty-sandy soil. The first 30 m of the line is in permafrost and the remaining section is in unfrozen ground. During the first phase of monitoring, chilled air with temperature between -4~ and -14~ was circulated through this 105 m long pipeline. The ground temperature measurements indicated that a frost bulb had developed in the non-permafrost ground. The mean monthly average temperature measured by the thermal fences indicated that the ground 2.0 m deep and 1 m away from the pipe center was reduced from -1.22~ in December 1999 to --4.6~ in December 2000. During the same period, the mean ground temperature at the 4 m depth gradually diminished from 0.18~ to -0.72~ and from -O.I~ to -0.18~ at the 8 m depth. Vertical upward movement of the pipeline caused by a frost front migrating out from the pipeline was noted. The maximum movements of the pipeline were 99.0 mm in the unfrozen area, 90.1 mm near the permafrost-non permafrost boundary, and 69.1 mm in the permafrost area. An empirical equation was developed to describe the ground temperature change. The statistical analysis indicated that air temperature had a less effect on the immediate ground (i.e. < 2 m from the pipeline center) than the pipeline temperature. 1Professor, Department of Mining and Geological Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775, USA; phone: 907-474-6880; ffslh@uaf.edu 2professor, Graduate School of Engineering, Hokkaido University, Sapporo, Japan 3Senior Engineer, Energy Industries Engineering Division, NKK Corporation, Yokohama, Japan 4professor, Department of Civil Engineering, Hokkai-Gakuen University, Sapporo, Japan 5Manager, Energy Facilities Engineering Division, Nippon Steel Corporation, Kanagawa, Japan 6General Manager, Energy Facilities Engineering Division, Nippon Steel Corporation, Tokyo, Japan 7professor, Institute of Low Temperature Sciences, Hokkaido University, Sapporo, Japan

Laboratory creep tests of frozen gravels

Abstract As part of a continuing effort to develop a relationship between convergence of full-scale underground openings in permanently frozen gravel and laboratory creep strength tests of frozen gravels, two uniaxial creep tests of reconstituted gravel were conducted at the University of Alaska-Fairbanks. The authors here present a description and the results of those tests.