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.

The segregation potential of a freezing soil

1981 ◽  
Vol 18 (4) ◽  
pp. 482-491 ◽  
Author(s):  
Jean-Marie Konrad ◽  
Norbert R. Morgenstern
Keyword(s):  
Temperature Gradient ◽  
General Theory ◽  
Water Intake ◽  
Linear Relation ◽  
Frost Heave ◽  
Cold Side ◽  
One Dimensional ◽  
Freezing Soil ◽  
Segregation Potential ◽  
Measured Water

In previous work it has been shown that when a soil sample freezes in a one-dimensional manner under different cold-side step temperatures but the same warm-side temperature, at the formation of the final ice lens the water intake flux is proportional to the temperature gradient across the frozen fringe. The constant of proportionality has been called the segregation potential and this linear relation constitutes the coupling between heat and mass flow in a general theory of frost heave. This paper shows experimentally that the segregation potential is also a function of the average suction in the frozen fringe which is readily expressed in terms of the suction at the frost front. As a result it is also shown that measured water intake flux during freezing is dependent on the freezing path used to initiate the final ice lens. A thermodynamic explanation of the dependence of segregation potential on suction in the frozen fringe is also offered.

Discrete ice lens theory for frost heave in soils

1991 ◽  
Vol 28 (6) ◽  
pp. 843-859 ◽  
Author(s):  
J. F. (Derick) Nixon
Keyword(s):  
Hydraulic Conductivity ◽  
Temperature Gradient ◽  
Frozen Soil ◽  
Soil Freezing ◽  
Frost Heave ◽  
Overburden Pressure ◽  
Discrete Location ◽  
Freezing Soil ◽  
Analytical Technique ◽  
Segregation Potential

The existing segregation potential (SP) method for frost heave prediction in soils is semiempirical in nature and does not explicitly predict the relationship between heave rate, temperature gradient, and other more fundamental soil properties. The SP method assumes that the heave rate is directly related to the temperature gradient at the frost front but acknowledges that the SP parameter is dependent on pressure, suction at the frost front, cooling rate, soil type, and so forth. This paper extends and modifies an approximate analytical technique of Gilpin and accounts for the effects of distributed phase change within the freezing fringe in both the head- and mass-transfer components of the formulation. The approach requires as input a relationship between frozen hydraulic conductivity and temperature and predicts the discrete location of each ice lens within the freezing soil. The solution can be carried out quickly on a microcomputer to obtain the heave, suction at the frost front, ice lens temperature, and other results of interest with time. Furthermore, the discrete ice lens method predicts the effects of changing overburden pressure on the predicted heave rate. A method of extracting input parameters for the discrete ice lens procedure from a series of frost heave tests is proposed. The discrete ice theory has been tested and calibrated against well-documented frost heave test results in the literature, and very encouraging agreement between prediction and observation has been obtained. Key words: frost heave, discrete ice lens, segregation potential, hydraulic conductivity of frozen soil, freezing soil.

A mechanistic theory of ice lens formation in fine-grained soils

1980 ◽  
Vol 17 (4) ◽  
pp. 473-486 ◽  
Author(s):  
Jean-Marie Konrad ◽  
Norbert R. Morgenstern
Keyword(s):  
Steady State ◽  
Heat Flow ◽  
Freezing Temperature ◽  
Cold Side ◽  
Freezing Soil ◽  
Fine Grained ◽  
Mechanistic Theory ◽  
Two Parameters ◽  
Lens Formation

This study reveals that a freezing soil can be characterized by two parameters, the segregation-freezing temperature Ts and the overall permeability of the frozen fringe [Formula: see text]. During unsteady heat flow, the variation of these parameters with temperature produces rhythmic ice banding in fine-grained soils. At the onset of steady-state conditions, freezing tests conducted at a fixed warm end temperature showed that Ts was independent of the cold side step temperature. In addition, a model is presented that indicates how the overall permeability of the frozen fringe can be calculated without detailed measurements at the scale of the frozen fringe. It is also constant in the tests reported here.

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.

Segregation potential – pressure – salinity relationships near thermal steady state for a clayey silt

1990 ◽  
Vol 27 (2) ◽  
pp. 203-215 ◽  
Author(s):  
J.-M. Konrad
Keyword(s):  
Steady State ◽  
Pore Water ◽  
Moisture Transfer ◽  
Frost Heave ◽  
Water Salinity ◽  
Saline Soils ◽  
Clayey Silt ◽  
Segregation Potential ◽  
Pore Water Salinity ◽  
Thermal Steady State

Laboratory freezing tests were performed on a saturated clayey silt at various pore-water salinities and applied pressures to establish the relationships between pore-water salinity, overburden, and the amount of moisture transfer during freezing near thermal steady state conditions. The experimental data confirmed that the concept of segregation potential established for salt-free soils can be extended to saline soils. The segregation potential at the onset of the final ice lens in step-freezing tests (or near thermal steady state) should be related to the average salinity of the frozen fringe associated with the final ice lens. This pore-water salinity is different from the initial pore-water salinity as a result of solute exclusion at the ice lenses causing an enrichment as freezing proceeds. Unfortunately, it is very difficult to determine the average salinity in the frozen fringe owing to its small size. Instead, it is proposed to use the initial water salinity to develop the constitutive equations in freezing saline soils. A procedure for frost heave predictions in the field is outlined. Key words: freezing tests, clayey silt, saline water, frost heave.

Sixteenth Canadian Geotechnical Colloquium: Frost heave in soils: concepts and engineering

1994 ◽  
Vol 31 (2) ◽  
pp. 223-245 ◽  
Author(s):  
J.-M. Konrad
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Point Of View ◽  
Frost Heave ◽  
Fundamental Point ◽  
New Concepts ◽  
Segregation Potential ◽  
Thermal Histories ◽  
Ice Content ◽  
Lens Formation

Frost heave in soils is analysed from a fundamental point of view to predict the development of periodic ice lens formation that is observed in frozen soils. A model of simultaneous heat and mass transfer associated with three new concepts is described and was found to exhibit many of the frost heave features observed in laboratory tests. An efficient frost heave parameter termed the segregation potential, SP, is also described and found to be an adequate input to a general formulation of heat and mass transfer for the prediction of frost heave in soils for both laboratory and field conditions. Representative values of SP depend on the stress and thermal histories of the soil deposit. The SP-based approach can be used for solving two-dimensional frost heave problems and yields stress, temperature, and ice-content distributions with time. Key words : frost heave, soils, segregation potential, simulation, thermodynamics.

The Formation of Ice Lenses in Unidirectional and Multidirectional Freezing Soil

2013 ◽  
Vol 353-356 ◽  
pp. 68-73
Author(s):  
Xian Feng Zhu ◽  
Xiang Yang Wei ◽  
Xing Huang ◽  
Yun Peng Zhang
Keyword(s):  
Temperature Gradient ◽  
Experimental Studies ◽  
Rectangular Cavity ◽  
Temperature Gradients ◽  
Frost Heave ◽  
Freezing Process ◽  
Soil Specimen ◽  
Plate Temperature ◽  
Freezing Soil ◽  
Unidirectional Freezing

Experimental studies were conducted on unidirectional and multidirectional freezing of artificial soils in a rectangular cavity. The ice lenses were observed through transparent plexiglass plate. Temperature gradients in soil specimen were obtained during freezing process. The experimental results indicated that the temperature gradient may change the shape of ice lenses. The amount of frost heave of multidirectional freezing was less than unidirectional freezing, so multidirectional freezing mode is helpful to restrain vertical frost heave.

scholarly journals Stress–Strain Model for Freezing Silty Clay under Frost Heave Based on Modified Takashi’s Equation

2020 ◽  
Vol 10 (21) ◽  
pp. 7753
Author(s):  
Lin Geng ◽  
Shengyi Cong ◽  
Jun Luo ◽  
Xianzhang Ling ◽  
Xiuli Du ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Compressive Modulus ◽  
Freezing Rate ◽  
Frost Heave ◽  
Gradient Term ◽  
Silty Clay ◽  
Stress Strain ◽  
Overburden Pressure ◽  
Freezing Soil ◽  
Strain Behavior

In analyzing frost heave, researchers often simplify the compressive modulus of freezing soil by considering it as a constant or only as a function of temperature. However, it is a critical parameter characterizing the stress–strain behavior of soil and a variable that is influenced by many other parameters. Hence, herein several one-dimensional freezing experiments are conducted on silty clay in an open system subjected to multistage freezing by considering the compressive modulus as a variable. First, freezing soil under multistage freezing is divided into several layers according to the frozen fringe theory. Then, the correlation between the freezing rate and temperature gradient within each freezing soil layer is investigated. Takashi’s equation for frost heave analysis is modified to extend its application conditions by replacing its freezing rate term with a temperature gradient term. A mechanical model for the stress–strain behavior of freezing soil under the action of frost heave is derived within the theoretical framework of nonlinear elasticity, in which a method for determining the compressive modulus of freezing soil with temperature gradient, overburden pressure, and cooling temperature variables is proposed. This study further enhances our understanding of the typical mechanical behavior of saturated freezing silty clay under frost heave action.

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.

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