Pile design in permafrost

1981 ◽  
Vol 18 (3) ◽  
pp. 357-370 ◽  
Author(s):  
J. S. Weaver ◽  
N. R. Morgenstern
Keyword(s):  
Reasonable Agreement ◽  
Field Data ◽  
Frozen Soil ◽  
Ultimate Capacity ◽  
Creep Data ◽  
Strength Data ◽  
Design Procedures ◽  
Soil Creep ◽  
Pile Design ◽  
Permafrost Soils

Principles for designing piles in permafrost on the basis of both ultimate capacity and limiting deformations are reviewed. Procedures developed previously for predicting settlement of piles in ice-rich soils are extended to ice-poor materials and shown to be in reasonable agreement with the modest amount of field data currently available. A compilation of data on allowable adfreeze strength data, frozen soil creep data, and pile design procedures has been undertaken to facilitate selecting allowable loads on piles in a broad range of permafrost soils. Illustrative examples are given in an Appendix.

In situ creep of frozen soil, Fenghuo Shan, Tibet Plateau, China

1995 ◽  
Vol 32 (3) ◽  
pp. 545-552 ◽  
Author(s):  
B. Wang ◽  
Hugh M. French
Keyword(s):  
Key Words ◽  
Power Flow ◽  
Field Data ◽  
Field Measurements ◽  
Frozen Soil ◽  
Tibet Plateau ◽  
Soil Creep ◽  
Extreme Variability ◽  
The Mean

Field measurements of frozen soil creep in the upper 3.0 m of permafrost indicate that creep occurs in both winter and summer. Between 1992 and 1993, the mean rate of creep ranged from 0.44 cm at 1.6 m depth to 0.16 cm at 2.8 m depth but there was extreme variability. Creep parameters n and A, as defined by the power flow law, were calculated from field data. Parameter n ranged between 1.96 and 2.29 and increased with depth, while A decreased with depth. Comparisons of creep rates for different permafrost environments suggest that ground temperature largely controls the magnitude of permafrost creep. Key words : permafrost, creep parameters, Tibet Plateau.

Creep and strength testing of frozen saline fine-grained soils

1984 ◽  
Vol 21 (3) ◽  
pp. 518-529 ◽  
Author(s):  
J. F. Nixon ◽  
G. Lem
Keyword(s):  
Shear Strength ◽  
Creep Rate ◽  
Constant Strain Rate ◽  
Frozen Soil ◽  
Unfrozen Water ◽  
Saline Soils ◽  
Creep Data ◽  
Creep Tests ◽  
Test Environment ◽  
Fine Grained

Little creep data is available for frozen, fine-grained saline soils. Salinity accelerates the creep rate of a frozen soil under load and reduces its shear strength owing to the higher unfrozen water contents in the pore phase. Creep data for saline fine-grained soils are required by engineers and scientists working in areas of coastal or offshore permafrost. The data are also used in projects involving artificial freezing of saline soils.This paper describes the results of 34 creep tests and 11 time-dependent strength tests carried out on saline soils. The tests were carried out for two different research programs; consequently, two different fine-grained soil types were used. Most of the tests were carried out in a constant stress and constant temperature creep test environment. Some were completed in a triaxial (constant strain rate) test format, in order to extend the data base to an area of higher strain rates. The range of temperatures was −2.3 to −25 °C, the range of stresses in the creep tests was 30–400 kPa, and the salinity was varied from 0–35 parts per thousand (ppt). Particular attention was paid to the lower stresses (30–200 kPa) and intermediate to high salinities (18–35 ppt). A high percentage of the creep tests was completed in the temperature range −5 to −10 °C, as this appears to be a typical ground temperature in coastal permafrost areas in Arctic Canada.Results indicate that the presence of pore fluid with a salinity approaching that of seawater causes a 10- to 100-fold increase in uniaxial creep rate, which can result in significant decreases in shear strength and foundation bearing capacity in saline permafrost areas.Soil resistivity tests were also carried out on frozen samples of different salinities. A strong correlation between resistivity and pore water salinity emerged. This has application in the interpretation of results from electrical resistivity surveys in permafrost. Key words: permafrost, saline, creep, strength, resistivity, fine-grained, offshore permafrost.

Behavior of Circular Footings and Plate Anchors Embedded in Permafrost

1974 ◽  
Vol 11 (4) ◽  
pp. 531-553 ◽  
Author(s):  
B. Ladanyi ◽  
G. H. Johnston
Keyword(s):  
Mathematical Model ◽  
Bearing Capacity ◽  
Soil Mechanics ◽  
Normal Pressure ◽  
Strength Properties ◽  
Frozen Soil ◽  
Time Dependent ◽  
Nonlinear Viscoelastic ◽  
Permafrost Soils ◽  
Failure Loads

The purpose of this paper is to develop a method for predicting the creep settlement and the bearing capacity of frozen soils under deep circular loads. The theory uses experimentally determined creep parameters of frozen soil and is intended to be applicable to the design of deep circular footings and screw anchors embedded in permafrost soils. On the basis of available experimental evidence, it was concluded that a mathematical model different from that usual in soil mechanics should be used in solving the time-dependent bearing capacity problem of such footings. The solution proposed in the paper was obtained by using the mathematical model of an expanding spherical cavity in a nonlinear viscoelastic-plastic medium with time, temperature, and normal pressure dependent strength properties. For a given footing or anchor, the theory furnishes either isochronous load-displacement curves, or load-creep rate curves, or a time-dependent bearing capacity for which formulas and graphs of nonlinear elastic-plastic bearing capacity factors are supplied.The theoretical predictability of creep rates and ultimate failure loads was checked against the results of screw anchor tests carried out by the Division of Building Research, N.R.C.C., at a permafrost site in Thompson, Manitoba. It was found that the use in the theory of the creep parameters determined by creep-pressuremeter tests performed at the site, resulted in a satisfactory agreement between the predicted and the observed behavior.

scholarly journals Metabolic Activity of Permafrost Bacteria below the Freezing Point

2000 ◽  
Vol 66 (8) ◽  
pp. 3230-3233 ◽  
Author(s):  
E. M. Rivkina ◽  
E. I. Friedmann ◽  
C. P. McKay ◽  
D. A. Gilichinsky
Keyword(s):  
Stationary Phase ◽  
Metabolic Activity ◽  
Incubation Temperature ◽  
Freezing Point ◽  
Growth Curves ◽  
Frozen Soil ◽  
Thin Layers ◽  
Unfrozen Water ◽  
Permafrost Soils ◽  
Siberian Permafrost

ABSTRACT Metabolic activity was measured in the laboratory at temperatures between 5 and −20°C on the basis of incorporation of14C-labeled acetate into lipids by samples of a natural population of bacteria from Siberian permafrost (permanently frozen soil). Incorporation followed a sigmoidal pattern similar to growth curves. At all temperatures, the log phase was followed, within 200 to 350 days, by a stationary phase, which was monitored until the 550th day of activity. The minimum doubling times ranged from 1 day (5°C) to 20 days (−10°C) to ca. 160 days (−20°C). The curves reached the stationary phase at different levels, depending on the incubation temperature. We suggest that the stationary phase, which is generally considered to be reached when the availability of nutrients becomes limiting, was brought on under our conditions by the formation of diffusion barriers in the thin layers of unfrozen water known to be present in permafrost soils, the thickness of which depends on temperature.

Full-displacement pressuremeter method for rigid piles under lateral loads and moments

1987 ◽  
Vol 24 (4) ◽  
pp. 471-478 ◽  
Author(s):  
G. G. Meyerhof ◽  
V. V. R. N. Sastry
Keyword(s):  
Model Test ◽  
Reasonable Agreement ◽  
Lateral Pressure ◽  
Layered Soil ◽  
Horizontal Load ◽  
Ultimate Capacity ◽  
Lateral Loads ◽  
Inclined Loads ◽  
Pure Moment ◽  
Rigid Model

The results of full-displacement pressuremeter tests in beds of sand, clay, and layered soil have been used to estimate the lateral soil pressures, ultimate capacity, and displacements of instrumented rigid model piles under eccentric and inclined loads. Comparisons of these estimates with observations on the piles under horizontal load and pure moment have been made and reasonable agreement is found. The analyses are also compared with some field case records. Key words: bearing capacity, clay, displacements, horizontal load, lateral pressure, layered soil, model test, moment, pile, pressuremeter, sand.

scholarly journals A Case Study of Pipeline Route Selection and Design Through Discontinuous Permafrost Terrain in Northwestern Alberta

1996 ◽  
Author(s):  
Cory Wiechnik ◽  
Raymond Boivin ◽  
Jim Henderson ◽  
Mark Bowman
Keyword(s):  
Life Cycle Cost ◽  
Field Data ◽  
Differential Settlement ◽  
Frozen Soil ◽  
Geophysical Data ◽  
Design Solution ◽  
Pipeline System ◽  
Permafrost Degradation ◽  
Discontinuous Permafrost ◽  
Pipeline Route

As the natural gas pipeline system in Western Canada expands northward, it traverses the discontinuous permafrost zone. As the ground temperature of the frozen soil in this zone is just below freezing, it can be expected that within the design life of a pipeline the permafrost adjacent to it will melt due to the disturbance of the insulating cover by construction activities. Differential settlement at the thawing frozen/unfrozen soil interfaces gives rise to pipeline strain. Based on the calculated settlement and resulting strain level, a cost effective mechanical or civil design solution can be selected to mitigate the differential settlement problem. Since these design solutions can be costly, it is desirable to combine them with a pipeline route that traverses the least amount of discontinuous permafrost terrain while minimizing the overall length of the pipeline. This paper will detail the framework utilized to select the routing for a package of pipeline projects in northwestern Alberta. The process began with a review of the state of the art in permafrost engineering in order to benefit from past experiences. Airphoto interpretation and terrain mapping were performed for potential pipeline corridors. Preliminary routing options through the corridors were chosen from this mapping information that minimized both pipeline length and amount of permafrost terrain traversed. The next step was to collect field data for each route that would determine the extent and characteristics of the permafrost. Essentially two sets of field data were collected: geophysical mapping of representative sections of each terrain type and physical sampling of the permafrost. Boreholes were located following field interpretation of the geophysical data to ensure they were optimally located to help in calibration of the geophysical data. Permafrost samples were tested in the laboratory for thaw settlement. Anticipated thaw settlements were used to estimate pipe strain levels. This information was then extrapolated for the entire proposed pipeline route and used to finalize both the pipeline route and the differential settlement design options. Monitoring sites will be instrumented to obtain data on the longer term performance of the pipeline, as well as for assessing permafrost degradation effects on the right-of-way such as settlement and impact on drainage patterns. It is believed that the increased front end effort will result in lower operating costs and an overall reduced life-cycle cost. This basic design methodology can be applied to any project that traverses discontinuous permafrost terrain.

scholarly journals Structural-technological solutions for the construction of roads on permafrost soils

2018 ◽  
Vol 5 (4) ◽  
Author(s):  
Aleksei Makarov ◽  
Alexey Kraev ◽  
Zurab Shankhoev
Keyword(s):  
Numerical Modeling ◽  
Thermal Regime ◽  
Soil Mass ◽  
Frozen Soil ◽  
Thermal Mode ◽  
Technological Solution ◽  
The Road ◽  
Permafrost Soils ◽  
Engineering Principle ◽  
Nenets Autonomous

In this article, the authors briefly reviewed the problem of building roads on permafrost soils, according to the first engineering principle. The probable causes, affecting the thermal regime of the frozen soil at the base of the road, are also considered. In order to stabilize the road structure on permafrost soils, the team of authors of this article proposed 3 structural-technological solutions for the construction of roads, depending on the moisture levels of the upper soil mass, calculated for geotechnical and temperature-humidity conditions typical for the Yamalo-Nenets Autonomous district. The scheme, description and assessment of the effectiveness of each proposed structural-technological solution is given. Efficiency of the assessment is based on a comparison of the numerical modeling results of the water-thermal mode of mound with the proposed structural-technological solutions and ground embankments of roads on permafrost. The results of the numerical modeling of road embankments on permafrost soils are presented. The main conclusions of the research are formulated.

scholarly journals An experimental study of a forced ventilation pile

Vestnik MGSU ◽  
2020 ◽  
pp. 665-677
Author(s):  
Nikita S. Okorokov ◽  
Alexandr N. Korkishko ◽  
Anastаsiya P. Korzhikova
Keyword(s):  
Educational Institution ◽  
Soil Layer ◽  
Thermal Stabilization ◽  
Frozen Soil ◽  
Temperature Fields ◽  
Federal State ◽  
Central Research ◽  
Forced Ventilation ◽  
Scaled Model ◽  
Permafrost Soils

Introduction. Thermal stabilization of foundation soils is a most widely spread method of engineering protection of structures in the cryolithic zone. Presently, as a rule, any construction is feasible if the footing temperature remains negative in the regions that have permafrost soils. In the article, the co-authors have analyzed a conceptually new method of thermal stabilization of soil, that is, the application of forced ventilation piles. The goal of the laboratory experiments is to simulate the frozen soil behaviour in case of its exposure to a ventilated and cooled pile. The co-authors have solved the problem of soil temperature reduction to ensure the soil transition from the thawed state into the frozen or plastic frozen state. Besides, the co-authors have substantiated the efficiency of this thermal stabilization method. The subject of this research is a ventilated pile, driven into sandy soil and ventilated by the cool air generated by the refrigerating unit. Materials and methods. A laboratory study of a scaled model. Results. According to the data provided by the temperature sensors, a forced ventilation pile kept the soil frozen in the radius of 10 cm as of the end of the second winter, which means 2 meters, given the scale factor of the experiment. This methodology can also be applied as a method of thermal stabilization and refrigeration of soils. In the course of the experiment, thawed soil froze. In summer, the seasonal active soil layer thawed, and negative temperatures remained unchanged and generated a frost table registered by the temperature fields, used in the summer period. Conclusions. Soil remains frozen in summer; the bearing capacity of the pile remains unchanged. Acknowledgements: The co-authors would like to express thanks to the Central research and development laboratory of permafrost research of the Federal State Budgetary Educational Institution of Higher Education Tyumen Industrial University, and to anonymous reviewers.

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