Frost heave and dry density changes during cyclic freeze-thaw of a silty clay
China ; Clay ; Cold area ; Experimentation ; Freeze-thaw cycle ; Frost ; Geotechnics ; Qinghai ; Railway ; Tibet
Open-system frost heave tests were performed on a silty clay using a lower boundary condition of +2°C and unidirectional freezing at -10°c from the surface, or freezing and thawing with an upper boundary temperature that cycled from -10°C to +10°C
or from -10°C to 0°C. The amont of frost heave, the distribution of moisture at the end of the experiment and the final dry density profiles all differed for the 3 cases. The experiments demonstrate that freeze-thaw history is important in assessing
Origin and polycyclic behaviour of tundra thaw slumps, Mackenzie Delta region, Northwest Territories, Canada
Canada ; Cold area ; Delta ; Mass movement ; Northwest Territories ; Periglacial features ; Permafrost ; Soil temperature ; Thawing ; Thermokarst ; Tundra
The focus of this paper is the tundra uplands east of the Mackenzie Delta. The AA. describe the influence of thaw slumping on ground thermal conditions in tundra environments and examines the role of warming permafrost on talik enlargement
as a mechanism driving the polycyclic behaviour of lakeside thaw slumps. The linkage between polycyclic thaw slump activity and talik expansion was investigated by : 1) examining the frequency of association between active slumps and areas of previous disturbance
Patterns in vegetation composition, surface height and thaw depth in polygon mires in the Yakutian Arctic (NE Siberia) : a microtopographical characterisation of the active layer
in thaw depths and strong correlation with relief, water and vegetation. Average thaw depths in polygon ridges (23 cm and 31 cm) were smaller than in depressions (33 cm and 40 cm, respectively). The greatest thaw depths, however, were also found
-existing fragipan is congruent with the inferred palaeo-permafrost table. The high bulk density of the fragipan was probably enhanced by either thaw consolidation when icy permafrost degraded at the active layer-permafrost interface or by liquefaction
Active layer ; Canada ; Climate ; Climatic index ; Climatic variability ; Cold area ; Interannual variability ; Northwest Territories ; Organic materials ; Periglacial features ; Permafrost ; Soil moisture ; Summer ; Thawing ; Valley
In this paper, results from active-layer probing on grids and thaw tubes are presented and spatial and temporal variations discussed in the context of local site characteristics and measurement methodologies. The AA. address 2 important questions
Freeze-thaw cycle ; High mountain ; Himalaya ; Insolation ; Mountain ; Nepal ; Rockfall ; Slope dynamics ; Snow ; Surface temperature ; Temperature
temperatures and exhibits seasonal freeze-thaw, whereas the other aspects show frequent diurnal freeze-thaw. These differences result in seasonal rockfall activity on the north-facing slope and the infrequent release of large debris and year-round rockfall
Canada ; Cartography ; Freezing ; Index ; Labrador ; Periglacial features ; Permafrost ; Quebec ; Remote sensing ; Surface temperature ; Thawing
distribution of permafrost and boundaries of the permafrost zones. The methodological approach is presented. Calculations of mean annual surface temperatures and of thawing and freezing indices led to the development of regional maps, in this case for northern
theory, the pits on top of Shigujian Peak are attributed to freezing-thawing of periglacial action. Meanwhile, storm and strong wind accelerate the process. Observation shows that both the actions are still undergoing and variant directions of wind
Freeze-thaw cycle ; Gully erosion ; Iowa ; Mass movement ; Meltwater ; Precipitation ; Underground water ; United States of America ; Valley ; Watershed
partly filled with water, measured heads were sufficient to cause bank failures through reduction of frictional support at the base of the slab. Deformation of the banks by heaving and thawing during winter may weaken them and prime them for failure
Bank erosion ; Channel geometry ; Flood ; Freeze-thaw cycle ; Gravel ; Meander ; Model ; Numerical model ; Pennsylvania ; River bed ; Stream ; United States of America
A-tents are also known as pop-ups and by several other local names. They consist of raised slabs or plates of various thicknesses and origins. Laminae are caused by weathering, and spall plates or slabs may be caused in part by freeze-thaw acting
Observations and measurements were made of physical and ecological changes that have occurred since 1985 at a tundra site near Healy, Alaska. Air temperatures decreased (1985 through 1999) while permafrost warmed and thawed creating thermokarst
China ; Digital elevation model ; Freeze-thaw cycle ; Global Positioning System ; Gully erosion ; Heilongjiang ; Seasonality ; Slope ; Soil erosion ; Water erosion
and the early 2000s, results and discussion about the correlation between surface movement, snow thickness and ground sub-surface temperatures. Finally, unusual surface lowering that accompanied peak velocities in 2004 may be due to a general thaw of the top