Ultrasonic wave measurements on frozen soils at permafrost temperatures

1976 ◽  
Vol 13 (11) ◽  
pp. 1571-1576 ◽  
Author(s):  
P. J. Kurfurst
Keyword(s):  
Geographical Location ◽  
Uniaxial Stress ◽  
Ultrasonic Pulse ◽  
Frozen Soil ◽  
Stress Conditions ◽  
Seismic Profiles ◽  
Pulse Technique ◽  
Wave Measurements ◽  
Seismic Records ◽  
Ice Content

An ultrasonic pulse technique was used in the laboratory to measure compressional and shear wave velocities on frozen soil samples with various ice contents. Measurements were made on a variety of samples, which differed in type of material, geographical location, and ice content, at temperatures ranging from −7 to +1 °C. Three series of tests were run on specimens from the Norman Wells, Fort Good Hope, and Eureka areas, Northwest Territories. The first series of specimens was tested under uniaxial stress conditions, whereas the measurements for the second and third series were done under triaxial stress conditions. The results measured on samples from the Norman Wells and Eureka areas were compared with the results obtained from shallow seismic profiles shot in the field at the sampled drill sites at the time of drilling. The values of field velocities lie within the range of laboratory measurements, and therefore prove that the laboratory tests provide a measure of control in the interpretation of seismic records.

Cumulative Damage in Fatigue under Multiaxial Stress Conditions

1974 ◽  
Vol 188 (1) ◽  
pp. 423-430 ◽  
Author(s):  
D. L. Mcdiarmid
Keyword(s):  
Experimental Investigation ◽  
Aluminium Alloy ◽  
Principal Stress ◽  
Stress Ratio ◽  
Uniaxial Stress ◽  
Cumulative Damage ◽  
Stress Conditions ◽  
Multiaxial Stress ◽  
Stress Ratios ◽  
Damage Criteria

Previous investigations into cumulative damage fatigue under uniaxial stress are discussed in conjunction with the parameters relevant to the present experimental investigation. The results of two-level block programme tests on 2L65 aluminium alloy at four values of constant principal stress ratio and at several combinations of two different principal stress ratios are presented and discussed with reference to cumulative damage criteria developed for the case of uniaxial fatigue stress.

Crustal structure of the Barents Sea from 3D active seismic tomography.

2020 ◽  
Author(s):  
Alexey Shulgin ◽  
Jan Erik Lie ◽  
Espen Harris Nilsen ◽  
Jan Inge Faleide ◽  
Sverre Planke
Keyword(s):  
Crustal Structure ◽  
Seismic Tomography ◽  
Barents Sea ◽  
Seismic Exploration ◽  
Seismic Profiles ◽  
Seismic Stations ◽  
S Waves ◽  
The Barents Sea ◽  
Seismic Records ◽  
Structural Architecture

<p>The Barents Sea shelf has been covered by numerous wide-angle seismic profiles aiming to resolve the crustal structure of the shelf. However, the overall structural architecture of the crystalline crust is still not fully understood, due to limited and sparse distribution of deep-sampling seismic profiles. </p><p>The petroleum related seismic exploration in Norwegian waters has been ongoing for decades. The recent increase of the seismic broadband stations onshore (including temporal deployments) provokes the idea to use these stations and the active seismic sources from the regional seismic reflection surveys, including academic and industry seismic projects, to reveal the crustal-scale structure of the western Barents Sea.</p><p>We have analyzed seismic records from 8 permanent seismic stations from Norway, Sweden and Finland, and 12 temporally deployed broadband seismic stations from the ScanArray seismic network, which recorded more than 100’000 marine airgun shots from academic and oil industry campaigns in the south-western quarter of the Barents Sea.</p><p>The overall quality of the seismic records is exceptionally good. We observe clear phases recorded from offsets reaching 750 km. The identified phases include refracted crustal and mantle arrivals as well as Moho reflections, including both P and S waves. The overall quantity, quality, and the geometry of the seismic data makes it perfect for the application of the 3D joint refraction/reflection travel time seismic tomography to study the crustal structure of the Barents Sea. In this work we would like to present our first results from the 3D seismic tomography.</p>

Transport of water in frozen soil: III. Experiments on the effects of ice content

1984 ◽  
Vol 7 (1) ◽  
pp. 28-34 ◽  
Author(s):  
Yoshisuke Nakano ◽  
Allen Tice ◽  
Joseph Oliphant
Keyword(s):  
Frozen Soil ◽  
Ice Content

scholarly journals Development and Testing of a Frozen Soil Parameterization for Cold Region Studies

2007 ◽  
Vol 8 (4) ◽  
pp. 690-701 ◽  
Author(s):  
Xia Zhang ◽  
Shu Fen Sun ◽  
Yongkang Xue
Keyword(s):  
Phase Change ◽  
Water Flow ◽  
Liquid Water ◽  
Frozen Soil ◽  
Picard Iteration ◽  
Richards Equation ◽  
Cold Region ◽  
Field Station ◽  
Mixed Form ◽  
Ice Content

Abstract Proper simulation of soil freezing and thawing processes is an important issue in cold region climate studies. This paper reports on a frozen soil parameterization scheme for cold region studies that includes water flow and heat transfer in soil with water phase change. The mixed-form Richards’ equation is adopted to describe soil water flow affected by thermal processes in frozen soil. In addition, both liquid water and ice content have been taken into account in the frozen soil hydrologic and thermal property parameterization. To solve the complex nonlinear equation set and to ensure water conservation during simulation of complex phase change processes, efficient computational procedures have been designed and a new modified Picard iteration scheme is extended to solve the mixed-form Richards’ equation with phase change. The frozen soil model was evaluated using observational data from the field station at Rosemount, Minnesota, and the Tibet D66 site. The results show that the model is capable of providing good simulations of the evolution of temperature and liquid water content in frozen soil. Comparisons of simulation results from sensitivity studies indicate that there is a maximum difference of about 50 W m−2 in sensible and ground heat fluxes with and without the inclusion of the effect of ice content on matric potential and that using the exponential relationship between hydraulic conductivity and ice content produces realistic results.

Applications of geophysical techniques in permafrost regions

1977 ◽  
Vol 14 (1) ◽  
pp. 117-127 ◽  
Author(s):  
W. J. Scott ◽  
J. A. Hunter
Keyword(s):  
Seismic Velocity ◽  
Seismic Refraction ◽  
Beaufort Sea ◽  
Test Site ◽  
The Arctic ◽  
Seismic Profiles ◽  
Refraction Seismic ◽  
Lake Bottom ◽  
Ice Content ◽  
The Hill

This paper reports the results of some recent geophysical experiments carried out in the Arctic with a variety of methods. In the Beaufort Sea, seismic refraction profiles obtained with both source and receivers on the seabottom indicate the presence of discontinuous near-bottom high-velocity (4200 m/s) material interpreted to be presently aggrading permafrost. Spring-time resistivity soundings taken through the ice in Kugmallit Bay, Beaufort Sea, show the top of permafrost at about 50 m below the bottom. Even for 5-km spreads, the base of permafrost was not observed.Off the southeast coast of Melville Island, refraction seismic profiles shot on the seabottom and resistivity soundings made through summer ice yielded data which correlate with known sub-bottom geology, but which gave no clear indication of either presence or absence of permafrost.Seismic and resistivity measurements made at a number of control sites in the Arctic Islands yielded typical velocities of 3500 m/s and resistivities of 1 × 106 ohm-m for ice-saturated sands. Some correlation was observed between seismic velocity and moisture contents in the range from 10% to 40%.Seismic and resistivity results in IOL Lake at the Involuted Hill test site, Tuktoyaktuk Peninsula, suggest the absence of permafrost under some parts of the lake bottom. On the hill itself, seismic up-hole shooting and VLF resistivity profiling give interpretations of ice distribution which correlate well with drill control. Gamma-gamma logs taken in some of the drill holes correlate well with ice content logged during drilling.

In situ measurements of moisture and salt movement in freezing soils

1986 ◽  
Vol 23 (5) ◽  
pp. 696-704 ◽  
Author(s):  
D. M. Gray ◽  
R. J. Granger
Keyword(s):  
Soil Moisture ◽  
Moisture Transfer ◽  
Freezing Point ◽  
Frozen Soil ◽  
Vapor Flow ◽  
Silty Clay ◽  
Upward Movement ◽  
Silt Loam ◽  
Freezing Front ◽  
Ice Content

The paper presents the results of field studies on the movement of moisture and salts during freezing of Prairie soils. It is shown that large fluxes of water can migrate to the freezing front and move upward into the frozen soil above. The fluxes are largest in light-textured soils (e.g., silt loam) having a water table at shallow depth. However, substantial amounts of soil moisture may also move in silty clay, silty clay loam, and clay soils under dryland farming provided there is sufficient water present to support capillary flow.The dynamics of soil moisture transfer under natural conditions as a result of freezing involves movement of water in both vapor and liquid phases. In the shallow surface layer of soil, to a depth of 300–400 mm, vapor flow predominates; in the depth below, water usually moves primarily as a liquid. It is demonstrated that the accumulation of ice with time increases because of the downward movement of the freezing front and the upward movement of water into the frozen soil above. In a silt loam with large fluxes, the ice content of the frozen zone rapidly reaches a level (80–85% pore saturation) where measurable migration ceases. Conversely, in a silty clay the movement of moisture into the frozen soil is observed to continue throughout most of the freezing period, and the ice content reaches 93% pore saturation. The greater movement in the finer grained soil is attributed to a higher freezing-point depression, a larger number of capillary pores, and a higher concentration of soluble salts in the liquid films.A close association is observed between changes in the ice content and electrical conductivity of a silt loam after freezing. In a silty clay the agreement is less clear, probably the result of the exchange of ions between the migrating liquid water and the clay particles. Maximum amounts of exchangeable ions moving into a 1 m depth of soil by the freezing action are estimated to be 11.9 t/ha in a silt loam and 15.7 t/ha in a silty clay loam.Data showing the redistribution of water and salts during thawing are also presented and discussed.

scholarly journals Theoretical study of thermal damage in frozen soil

2015 ◽  
Vol 19 (4) ◽  
pp. 1419-1422
Author(s):  
Zhi-Wu Zhu ◽  
Yue Ma ◽  
Zhi-Jie Liu
Keyword(s):  
Dynamic Model ◽  
Thermal Damage ◽  
Theoretical Study ◽  
Volumetric Strain ◽  
Frozen Soil ◽  
Ice Content

The weakened strength of frozen soil caused by rising temperature can result in thermal damage, which is mainly affected by ice content. A dynamic model for frozen ice is proposed considering temperature and volumetric strain.

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