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.

scholarly journals Application of the Segregation Potential Model to Freezing Soil in a Closed System

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2418
Author(s):  
Xiyan Zhang ◽  
Yu Sheng ◽  
Long Huang ◽  
Xubin Huang ◽  
Binbin He
Keyword(s):  
Pore Water ◽  
Closed System ◽  
Potential Model ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Freezing Temperature ◽  
Frost Heave ◽  
Freezing Front ◽  
Freezing Soil ◽  
Segregation Potential

Previous studies have shown that an accurate prediction of frost heaves largely depends on the pore water pressure and hydraulic conductivity of frozen fringes, which are difficult to determine. The segregation potential model can avoid this problem; however, the conventional segregation potential is considered to be approximately unchanged at a steady state and only valid in an open system without dehydration in the unfrozen zone. Based on Darcy’s law and the conventional segregation potential, the segregation potential was expressed as a function of the pore water pressure at the base of the ice lens, the pore water pressure at the freezing front, the freezing temperature, the segregation freezing temperature and the hydraulic conductivity of the frozen fringe. This expression indicates that the segregation potential under quasi-steady-state conditions is not a constant in a closed system, since the pore water pressure at the freezing front varies with the freezing time owing to the dehydration of the unfrozen zone, and that when the pore water pressure at the freezing front is equal to that at the base of the ice lens, the water migration and frost heave will be terminated. To analyze the possibility of applying the segregation potential model in a closed system, a series of one-sided frost heave tests under external pressure in a closed system were carried out in a laboratory, and the existing frost heaving test data from the literature were also analyzed. The results indicate that the calculated frost heave was close to the tested data, which shows the applicability of the model in a closed system. In addition, the results show the rationality of calculating the segregation potential from the frost heaving test by comparing the potential with that calculated from the numerical simulation results. This study attempted to extend the segregation potential model to freezing soil in a closed system and is significant to the study of frost heaves.

Water flow induced by soil freezing

1977 ◽  
Vol 14 (2) ◽  
pp. 237-245 ◽  
Author(s):  
Wayne D. Arvidson ◽  
Norbert R. Morgenstern
Keyword(s):  
Freezing Temperature ◽  
Soil Freezing ◽  
Frost Heave ◽  
Freezing Front ◽  
Overburden Pressure ◽  
Soil Frost ◽  
Freezing Soil ◽  
Volumetric Expansion ◽  
Pressure Water

A study to observe the effects of overburden pressure and other parameters on the freezing behavior of a saturated soil was undertaken. A linear relationship between effective overburden pressure and the flow of water into or out of a freezing soil was observed. The effective pressure at which no flow occurred was termed the shutoff pressure. At pressures less than the shutoff pressure water was sucked to the freezing front resulting in segregated ice, ice lensing, and heaving. This heaving could significantly exceed the heave due to the volumetric expansion of the in situ porewater. At pressures greater than the shutoff pressure water was expelled from the freezing front thereby reducing the volume of in situ water and resulting in a relatively small amount of heave. Shutoff pressure was observed to depend on soil type, stress history, and freezing temperature. The effects of overburden pressure upon flow of water in a freezing soil and frost heave were recommended as additional criteria for assessing soil frost susceptibility.

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.

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.

Study on the Simulated Testing on Repairing Drainage Pipe of Connecting Passage of Metro Tunnel with the Method of Liquid Nitrogen Freezing

2011 ◽  
Vol 368-373 ◽  
pp. 2581-2585
Author(s):  
Yong Zhang ◽  
Feng Tian Yue ◽  
Rong Jian Shi ◽  
Lu Lu
Keyword(s):  
Liquid Nitrogen ◽  
Pipe Wall ◽  
Similarity Theory ◽  
Similarity Criterion ◽  
Freezing Temperature ◽  
Test System ◽  
Frost Heave ◽  
Drainage Pipe ◽  
Simulated Test ◽  
Metro Tunnel

The paper derives the similarity criterion aiming at the characteristics of repairing the drainage pipe with the method of the liquid nitrogen freezing in the connecting passage of metro tunnel, and establishes the simulated test system of the liquid nitrogen freezing based on the similarity theory. Through the simulated testing on repairing the drainage pipe with the method of liquid nitrogen freezing in the connecting passage of metro tunnel, we get the regulation of the temperature distribution of the freezing pipe wall, the regulation of the development of the freezing temperature field and the the frost heave displacement.The study instructs the repairing drainage pipe with the method of liquid nitrogen freezing in the connecting passage of metro tunnel, and promotes the development of the thoery of the liquid nitrogen freezing, also provides the reference and improvement for the engineering and study in the future.

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.

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.

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