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.

Field observations of frost action in intact and weathered Champlain Sea clay

1995 ◽  
Vol 32 (4) ◽  
pp. 689-700 ◽  
Author(s):  
J.-M. Konrad ◽  
M. Roy ◽  
P. La Rochelle ◽  
S. Leroueil ◽  
G. Bergeron
Keyword(s):  
Key Words ◽  
Frost Heave ◽  
Field Observations ◽  
Freeze Thaw ◽  
Frost Action ◽  
Intact State ◽  
Potential Value ◽  
Field Instrumentation ◽  
Segregation Potential ◽  
Undrained Strength

This paper presents the results of a field study on frost action in sensitive Saint–Alban clay both in an intact state, never subjected to any freeze–thaw cycles, and in its weathered state, corresponding to thousands of freeze–thaw cycles. It appears that intact clay is highly frost susceptible and displays frost heave of about 20 cm for the 1989–1990 freezing season. The segregation potential of intact clay ranges between 425 and 550 × 10−5 mm2/(s∙ °C), while that of the crust is only about 40 to 50 × 10−5 mm2/(s∙ °C). In the field, destructured clay displayed a segregation potential value of 265 × 10−5 mm2/(s∙ °C). Loss of bearing capacity during thaw of frozen intact clay is substantial, with reduction in undrained strength from 10 to 2.5 kPa. Key words : sensitive clays, frost heave, field, instrumentation, segregation potential.

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.

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.

scholarly journals Frost heave prediction of chilled pipelines buried in unfrozen soils

1984 ◽  
Vol 21 (1) ◽  
pp. 100-115 ◽  
Author(s):  
J.-M. Konrad ◽  
N. R. Morgenstern
Keyword(s):  
Mass Transfer ◽  
Test Site ◽  
Frost Heave ◽  
Saturated Soils ◽  
Buried Pipelines ◽  
Finite Difference Formulation ◽  
Segregation Potential ◽  
Pipe Insulation ◽  
Good Agreement

Frost heave is an important consideration in the design of buried chilled pipelines. A procedure for calculating the amount of heave under a chilled gas pipeline is presented based on a finite-difference formulation of the heat and mass transfer in saturated soils. The frost heave of the soil is characterized in terms of the segregation potential concept developed in earlier papers by the authors. Good agreement is found between the predictions of heave obtained with this procedure and that observed in long-term full-scale experiments at a test site in Calgary, Canada. Additional calculations are presented to explore the influence of pipeline temperature, pipe insulation, and ground temperature on frost heave of buried pipelines.

An electric propulsion long term test facility

1979 ◽  
Author(s):  
G. TRUMP ◽  
E. JAMES ◽  
R. VETRONE ◽  
R. BECHTEL
Keyword(s):  
Electric Propulsion ◽  
Test Facility

Planning a system of permanent sample plots for integrated long-term studies of community-based forest management

1970 ◽  
Vol 16 (2) ◽  
pp. 3-11 ◽  
Author(s):  
H Meilby ◽  
L Puri ◽  
M Christensen ◽  
S Rayamajhi
Keyword(s):  
Forest Management ◽  
Key Words ◽  
Research Note ◽  
Managed Forests ◽  
Community Based ◽  
Permanent Sample Plots ◽  
Long Term Studies

To monitor the development of four community-managed forests, networks of permanent sample plots were established in 2005 at sites in Chitwan, Kaski and Mustang Districts, Nepal. This research note documents the procedures used when preparing for establishment of the plot networks, evaluates the applied stratification of the forest on the basis of data gathered in pilot surveys conducted in the early 2005, and provides a discussion on the implications of the choices made. Key words: Community-managed forests; permanent sample plots; stratification; allocation; estimates Banko Janakari Vol.16(2) 2006 pp.3-11

Mandatory Reporting and Adolescent Sexual Assault

2021 ◽  
pp. 152483802110302
Author(s):  
Caroline Bailey ◽  
Jessica Shaw ◽  
Abril Harris
Keyword(s):  
Sexual Assault ◽  
Sexual Violence ◽  
Key Words ◽  
Scoping Review ◽  
Well Being ◽  
Mandatory Reporting ◽  
Age Group ◽  
Long Term Consequences ◽  
The Impact

Adolescents experience alarmingly high rates of sexual violence, higher than any other age-group. This is concerning as sexual violence can have detrimental effects on teens’ personal and relational well-being, causing long-term consequences for the survivor. Still, adolescents are hesitant to report the assault or seek out services and resources. When an adolescent survivor does seek out services, they may interact with a provider who is a mandatory reporter. This scoping review sought to synthesize the current U.S.-based research on the role, challenges, and impact of mandatory reporting (MR) in the context of adolescent sexual assault. Database searches using key words related to MR, sexual assault, and adolescence identified 29 peer-reviewed articles. However, none of these articles reported on empirical investigations of the phenomenon of interest and instead consisted of case studies, commentaries, and position papers. The scoping review was expanded to provide a lay of the land of what we know about the intersection of adolescent sexual assault and MR. Results of the review indicate that though implemented broadly, MR policies vary between individuals, organizations, and states and have historically been challenging to implement due to this variation, conflicts with other laws, tension between these policies and providers’ values, and other factors. Based on the available literature, the impact of MR in the context of adolescent sexual assault is unknown. There is a critical need for research and evaluation on the implementation and impact of MR policies, especially in the context of adolescents and sexual violence.

scholarly journals Genetic Consequences of Fence Confinement in a Population of White-Tailed Deer

Diversity ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 126
Author(s):  
Emily K. Latch ◽  
Kenneth L. Gee ◽  
Stephen L. Webb ◽  
Rodney L. Honeycutt ◽  
Randy W. DeYoung ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Mitochondrial Dna ◽  
Wildlife Management ◽  
Field Observations ◽  
Adaptive Potential ◽  
Population Isolation ◽  
Potential Benefits ◽  
Wildlife Populations ◽  
Mtdna Diversity

Fencing wildlife populations can aid wildlife management goals, but potential benefits may not always outweigh costs of confinement. Population isolation can erode genetic diversity and lead to the accumulation of inbreeding, reducing viability and limiting adaptive potential. We used microsatellite and mitochondrial DNA data collected from 640 white-tailed deer confined within a 1184 ha fence to quantify changes in genetic diversity and inbreeding over the first 12 years of confinement. Genetic diversity was sustained over the course of the study, remaining comparable to unconfined white-tailed deer populations. Uneroded genetic diversity suggests that genetic drift is mitigated by a low level of gene flow, which supports field observations that the fence is not completely impermeable. In year 9 of the study, we observed an unexpected influx of mtDNA diversity and drop in inbreeding as measured by FIS. A male harvest restriction imposed that year increased male survival, and more diverse mating may have contributed to the inbreeding reduction and temporary genetic diversity boost we observed. These data add to our understanding of the long-term impacts of fences on wildlife, but also highlight the importance of continued monitoring of confined populations.

scholarly journals Simulation of MASPn Experiments in MISTRA Test Facility with COCOSYS Code

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Mantas Povilaitis ◽  
Egidijus Urbonavičius
Keyword(s):  
Boundary Conditions ◽  
Nuclear Power ◽  
Power Plants ◽  
Volume Fraction ◽  
Characteristic Length ◽  
Initial Conditions ◽  
Test Facility ◽  
Work Package ◽  
Acceptable Agreement

An issue of the stratified atmospheres in the containments of nuclear power plants is still unresolved; different experiments are performed in the test facilities like TOSQAN and MISTRA. MASPn experiments belong to the spray benchmark, initiated in the containment atmosphere mixing work package of the SARNET network. The benchmark consisted of MASP0, MASP1 and MASP2 experiments. Only the measured depressurisation rates during MASPn were available for the comparison with calculations. When the analysis was performed, the boundary conditions were not clearly defined therefore most of the attention was concentrated on MASP0 simulation in order to develop the nodalisation scheme and define the initial and boundary conditions. After achieving acceptable agreement with measured depressurisation rate, simulations of MASP1 and MASP2 experiments were performed to check the influence of sprays. The paper presents developed nodalisation scheme of MISTRA for the COCOSYS code and the results of analyses. In the performed analyses, several parameters were considered: initial conditions, loss coefficient of the junctions, initial gradients of temperature and steam volume fraction, and characteristic length of structures. Parametric analysis shows that in the simulation the heat losses through the external walls behind the lower condenser installed in the MISTRA facility determine the long-term depressurisation rate.

Sign in / Sign up

Export Citation Format

Share Document