Field frost heave predictions using the segregation potential concept

1982 ◽  
Vol 19 (4) ◽  
pp. 526-529 ◽  
Author(s):  
John F. Nixon
Keyword(s):  
Field Conditions ◽  
Frost Heave ◽  
Test Facility ◽  
Potential Approach ◽  
Fine Grained ◽  
Practical Engineering ◽  
Segregation Potential ◽  
Pipe Lines

The Konrad–Morgenstern theory of frost heave using the segregation potential concept is briefly outlined, and the method of predicting frost heave under field conditions is reviewed. A recent paper by Nixon et al. describes the operation and results from two circular frost heave test plates installed at the Foothills Pipe Lines test facility in Calgary. The frost heave theory using the segregation potential approach has been applied in its simplest form to predict the frost heave beneath these test plates and the agreement is found to be very good. Current geothermal modelling, coupled with the Konrad–Morgenstern theory of frost heave, appears to be capable of reasonable predictions of frost heave in fine-grained soils under practical engineering conditions.

Subsoil investigation of ice lensing at the Calgary, Canada, frost heave test facility

1988 ◽  
Vol 25 (2) ◽  
pp. 307-319 ◽  
Author(s):  
L. E. Carlson ◽  
J. F. (Derick) Nixon
Keyword(s):  
Key Words ◽  
Potential Model ◽  
Frost Heave ◽  
Test Facility ◽  
Field Observations ◽  
Silty Soil ◽  
Temperature Environment ◽  
Segregation Potential ◽  
Control Section

Several frost heave mitigation modes were studied at the Calgary, Canada, chilled pipeline frost heave test facility. These included deeper burial (to increase the pressure on the frost front below the pipe) and replacement of the silty soil around the pipe with gravel for a noninsulated pipe. Frost heave at the deep-burial section and at the gravel section was less than the heave at a control section. Other pipe sections tested the effects of insulation of the pipe on the long-term frost heave, as well as the effects of replacing the silt around an insulated pipe with gravel. Summer thawing of the frost bulb around the insulated pipe results in seasonal thaw settlement of the pipe, thus reducing the long-term pipe heave, at least for the warmer ground temperature environment at the Calgary facility.Thermal simulations of the frost bulb growth and predictions of frost heave using the segregation potential model agree well with the observations.Recent excavation of two frost bulbs in silty soil led to field observations of the interior of the frost bulbs, and subsequent laboratory analysis of frost bulb samples. Ice distribution was logged and photographed following excavation of each frost bulb. Key words: frost heave, pipeline, silt, mitigation, instrumentation, field observations.

Effects of applied pressure on freezing soils

1982 ◽  
Vol 19 (4) ◽  
pp. 494-505 ◽  
Author(s):  
J.-M. Konrad ◽  
N. R. Morgenstern
Keyword(s):  
Applied Pressure ◽  
Freezing Temperature ◽  
Pressure Effects ◽  
Field Conditions ◽  
Frost Heave ◽  
Fringe Field ◽  
Freezing Front ◽  
Segregation Potential ◽  
Rate Of Cooling ◽  
Pressure Suction

Background studies illustrating the effect of externally applied pressure on frost heave are reviewed together with some of the thermodynamic aspects of pressure effects. New experimental data are presented to show how the segregation potential varies with applied pressure. This variation is explained in terms of the influence of applied pressure on the segregation-freezing temperature and the average permeability of the frozen fringe. An explanation is given of the change in mode from expulsion to attraction of water to the freezing front in a loaded soil and it is shown that segregation can be eliminated by externally applied loads. However, these loads are generally too high to be of engineering interest. While it has been concluded that, under laboratory freezing conditions, the segregation potential is dependent upon applied pressure, suction at the frost front, and rate of cooling of the frozen fringe, field conditions are often simpler. A simplified method of predicting frost heave under field conditions is developed that should lead to conservative results.

Estimation of the segregation potential of fine-grained soils using the frost heave response of two reference soils

2005 ◽  
Vol 42 (1) ◽  
pp. 38-50 ◽  
Author(s):  
Jean-Marie Konrad
Keyword(s):  
Empirical Relationship ◽  
Clay Mineralogy ◽  
Frost Heave ◽  
Free Access ◽  
Overburden Pressure ◽  
New Approach ◽  
Fine Grained ◽  
Average Grain Size ◽  
Fine Grained Soil ◽  
Segregation Potential

The frost heave response of quarry fines from several locations in the Province of Quebec was studied in the laboratory using one-dimensional step-freezing tests with free access to water. Comparison of the segregation potential values obtained from these tests with available data on fine-grained soils revealed the importance of including clay mineralogy and overburden effects in any predictive empirical relationship, especially when fines are nonclays. A new approach is presented to estimate segregation potential values using the frost heave response of two reference soils. The reference characteristics consist of a relationship between segregation potential at zero overburden pressure, specific surface area, and average grain size of the fines fraction for two artificial soil mixtures in which the clay mineral is poorly crystallized kaolinite. The prediction of segregation potential values using the reference frost heave characteristics approach is more robust and reliable than other empirical approaches that do not specifically distinguish between clay and nonclay fines. Furthermore, the new approach was also efficient for the assessment of frost susceptibility of well-graded glacial tills.Key words: fine grained, soil, mineralogy, laboratory, fines, clay, nonclay.

Prediction of frost heave in the laboratory during transient freezing

1982 ◽  
Vol 19 (3) ◽  
pp. 250-259 ◽  
Author(s):  
J.-M. Konrad ◽  
N. R. Morgenstern
Keyword(s):  
Mass Transfer ◽  
Steady State ◽  
Temperature Gradient ◽  
Water Intake ◽  
Applied Load ◽  
Frost Heave ◽  
Freezing Soil ◽  
Fine Grained ◽  
Segregation Potential ◽  
Rate Of Cooling

Previous studies have demonstrated that, close to steady-state conditions, the ratio of the water intake velocity to the temperature gradient across the frozen fringe, called the segregation potential, is an important property characterizing a freezing soil. Under the more general conditions of transient freezing it is shown that the freezing characteristics of a given soil under zero applied load are defined by the segregation potential, the suction at the frozen–unfrozen interface, and the rate of cooling of the frozen fringe. These parameters form a relationship called the characteristic frost heave surface that can be used to predict mass transfer during the freezing of fine-grained soils. Examples of freezing tests conducted under various conditions are reproduced numerically to illustrate the fundamental character of this surface.

Stress Analysis of Pipeline Subjected to Differential Frost Heave

2013 ◽  
Author(s):  
Yan Di ◽  
Jian Shuai ◽  
Lingzhen Kong ◽  
Xiayi Zhou
Keyword(s):  
Strain Analysis ◽  
Element Model ◽  
Frozen Soil ◽  
Computational Method ◽  
Frost Heave ◽  
Safe Operation ◽  
Stress Strain ◽  
Segregation Potential ◽  
Differential Frost Heave ◽  
Design Construction

Frost heave must be considered in cases where pipelines are laid in permafrost in order to protect the pipelines from overstress and to maintain the safe operation. In this paper, a finite element model for stress/strain analysis in a pipeline subjected to differential frost heave was presented, in which the amount of frost heave is calculated using a segregation potential model and considering creep effects of the frozen soil. In addition, a computational method for the temperature field around a pipeline was proposed so that the frozen depth and temperature variation gradient could be obtained. Using the procedure proposed in this paper, stress/strain can be calculated according to the temperature on the surface of soil and in a pipeline. The result shows the characteristics of deformation and loading of a pipeline subjected to differential frost heave. In general, the methods and results in this paper can provide a reference for the design, construction and operation of pipelines in permafrost areas.

Effects of Inlet Flow Field Conditions on the Stall Onset of Centrifugal Compressor Vaned Diffusers

2003 ◽  
Author(s):  
Sabri Deniz
Keyword(s):  
Flow Field ◽  
Axial Flow ◽  
Rotating Stall ◽  
Field Conditions ◽  
Test Facility ◽  
Straight Channel ◽  
Inlet Flow ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Operating Range

This paper considers the performance and operating range of vaned diffusers for use in high performance centrifugal compressors. An experimental and numerical investigation is performed to determine the effects of inlet flow field conditions on pressure recovery and stall onset of different type vaned diffusers, such as discrete-passage and straight-channel diffusers. Diffuser inlet flow conditions examined include Mach number, flow angle, blockage, and axial flow non-uniformity. The investigation was carried out in a specially built test facility, designed to provide a controlled inlet flow field to the test diffusers. Unsteady pressure measurements showed the operating range of a compressor stage was limited by the onset of rotating stall, triggered by the loss of stability in the vaned diffuser, independent of the impeller operating point. For both diffusers investigated, loss of flow stability in the diffuser occurred at a critical value of the momentum-averaged flow angle into the diffuser. To provide additional information on diffuser flow development and to complement previous experimental work performed on straight-channel type diffuser, a computational investigation has been undertaken and important results are presented.

scholarly journals Prediction of field frost heave using the segregation potential theory.

1988 ◽  
pp. 253-259
Author(s):  
Makoto FUKUDA ◽  
Shoji OGAWA ◽  
Takeshi KAMEI
Keyword(s):  
Potential Theory ◽  
Frost Heave ◽  
Segregation Potential

Frost heave characteristics of undisturbed sensitive Champlain Sea clay

1994 ◽  
Vol 31 (2) ◽  
pp. 285-298 ◽  
Author(s):  
J.-M. Konrad ◽  
J.T.C. Seto
Keyword(s):  
Pore Pressure ◽  
Laboratory Tests ◽  
External Source ◽  
Frost Heave ◽  
Water Fluxes ◽  
Excess Water ◽  
Segregation Potential ◽  
Structured Clay ◽  
Compressible Soil ◽  
Surface Heave

Undisturbed Champlain Sea clay samples were subjected to laboratory freezing tests with pore-pressure measurements in order to determine the freezing characteristics of a structured compressible soil. Step-freezing and ramped-freezing tests with applied back pressure were conducted on 10 cm high samples in open-system conditions. Significant pore-pressure reductions in the unfrozen soil induce important frost-induced consolidation and destructuration of the clay. It was found that the freezing characteristics of Saint-Alban clay are best defined by the segregation potential at the active ice lens, SPℓ, which includes water fluxes generated within the frozen fringe and within the unfrozen soil as excess water is expelled during consolidation, and finally water from an external source. For the Saint-Alban clay, SPℓ values of the intact clay ranged between 450 and 600 × 10−5 mm2/(s °C), whereas those of destructured clay at a lower void ratio were significantly smaller. Back-calculating the segregation potential solely from surface heave measurements in laboratory tests may underestimate considerably the frost susceptibility of compressible structured clays. Segregation potential inferred from instrumented field sites was 430 × 10−5 mm2/(s °C) and is consistent with the laboratory tests results. Key words : freezing, frost heave, structured clay, undisturbed, consolidation.

Frost susceptibility related to soil index properties

1999 ◽  
Vol 36 (3) ◽  
pp. 403-417 ◽  
Author(s):  
Jean-Marie Konrad
Keyword(s):  
Empirical Relationship ◽  
Liquid Limit ◽  
Frost Heave ◽  
Assessment Methodology ◽  
Index Properties ◽  
Susceptibility Assessment ◽  
Overburden Pressure ◽  
Compressibility Index ◽  
Segregation Potential ◽  
Average Size

The analysis of frost-heave data on several soils confirmed that segregation potential, hence frost susceptibility, of saturated soils was best related to the average size of the fines fraction, the specific surface area of the fines fraction, and the ratio of the material's water content to its liquid limit. The influence of overburden pressure can also be accounted for by an empirical relationship between the segregation potential, the average size of the fines fraction, and the compressibility index of the soil. The segregation potential was also proportional to the relative fines content in soils where the fines do not completely fill the voids of the coarser fraction. This study led to the development of a new frost-susceptibility assessment methodology based on simple geotechnical routine soil index testing that was validated on a highway site on frost-susceptible subgrade till.Key words: frost heave, index properties, criteria, soil, segregation potential.

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