The Closing of Ice-wedge Cracks in Permafrost, Garry Island, Northwest Territories

1975 ◽  
Vol 12 (9) ◽  
pp. 1668-1674 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Northwest Territories ◽  
Crack Width ◽  
Crack Spacing ◽  
Elastic Model ◽  
Thermal Contraction ◽  
Underground Cables ◽  
Ice Wedge ◽  
The Mean

The closing of thermal contraction (ice-wedge) cracks at Garry Island, N.W.T., 150 km northwest of Inuvik, N.W.T., has been measured by means of gauge probes inserted into the cracks and by precise taping between bench marks across ice-wedge troughs. The results show that a simple elastic model fails to explain the time of cracking, the depth of cracking, the crack spacing, and the time of closing. The mean annual ice vein increment, at Garry Island, is probably less than 20% of the mean winter crack width. Thermal contraction cracks are of potential engineering interest, because they may affect underground cables, reservoirs, and other man-made structures.

Late Holocene syngenetic ice-wedge polygons development, Bylot Island, Canadian Arctic Archipelago

2004 ◽  
Vol 41 (8) ◽  
pp. 997-1012 ◽  
Author(s):  
Daniel Fortier ◽  
Michel Allard
Keyword(s):  
Late Holocene ◽  
Canadian Arctic ◽  
Canadian Arctic Archipelago ◽  
Thermal Contraction ◽  
Current Configuration ◽  
Outwash Plain ◽  
Bylot Island ◽  
Ice Wedge ◽  
The Mean ◽  
Organic Sediments

The initial configuration of the syngenetic ice-wedge polygons that developed in the outwash plain of glacier C-79 after 6000 BP was modified by the accumulation of wind-blown and organic sediments that began after 3670 ± 110 BP. The late Holocene sedimentation led to an increase in the thermal contraction coefficient of the soil and the formation of third- and fourth-order contraction cracks, partially explaining the current configuration of the polygonal network. The upturning of the sedimentary strata bordering the ice wedges was associated with the summer thermal expansion and resulting internal creep of the soil. The mean annual soil displacement coefficient was in the order of 2.5–2.7 × 10–5 /°C at the thousand-year scale. The late Holocene sedimentary strata under the centre of the polygons were undisturbed, which will make it possible to use this sedimentary record in further studies to attempt paleoenvironmental reconstructions from cores.

Ice wedges on hillslopes and landform evolution in the late Quaternary, western Arctic coast, Canada

1995 ◽  
Vol 32 (8) ◽  
pp. 1093-1105 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Active Layer ◽  
Late Quaternary ◽  
Chronological Age ◽  
Bottom Slope ◽  
Thermally Induced ◽  
Landform Evolution ◽  
Ice Wedge ◽  
Western Arctic ◽  
Arctic Coast ◽  
The Mean

In rolling to hilly areas of the western Arctic coast of Canada, anti-syngenetic wedges, which by definition are those that grow on denudational slopes, are the most abundant type of ice wedge. Through prolonged slope denudation, hilltop epigenetic wedges can evolve into hillslope anti-syngenetic wedges, and some bottom-slope anti-syngenetic wedges, by means of deposition from upslope, can evolve into bottom-slope syngenetic wedges. The axis of a hillslope wedge is oriented perpendicular to the slope, so the wedge foliation varies according to the trend of the wedge with respect to the slope. Because the tops of hillslope wedges are truncated by slope recession, the mean chronological age of anti-syngenetic wedge ice decreases with time, so the growth record for an old wedge is incomplete. Summer and winter measurements show that a thermally induced net movement of the active layer of hillslope polygons tends to transport material from their centres towards their troughs independent of the trends of the troughs relative to the slope. Wedge-ice uplift, probably diapiric, has been measured. Some hillslope polygon patterns may predate the development of the present topography. Many Wisconsinan wedges, truncated and buried during the Hypsithermal period, have been reactivated by upward cracking.

scholarly journals Transverse Crack Behavior in Continuously Reinforced Concrete Pavement with Basalt Fiber Reinforcement

2020 ◽  
Vol 10 (21) ◽  
pp. 7458
Author(s):  
Yating Zhang ◽  
Zhiyi Huang
Keyword(s):  
Elastic Modulus ◽  
Reinforced Concrete ◽  
Crack Width ◽  
Basalt Fiber ◽  
Concrete Pavement ◽  
Crack Spacing ◽  
Design Parameters ◽  
Mean Values ◽  
Crack Behavior ◽  
Reinforcement Content

Continuously reinforced concrete pavement (CRCP) is a pavement structure with a high performance and long service life. However, the corrosion of the longitudinal steel can result in a poor bond relationship between the steel and the concrete, affecting the load transfer efficiency between the adjacent panels and being responsible for the development of CRCP distresses. Basalt fiber-reinforced polymer (BFRP) is corrosion-resistant and has the potential to be used in CRCP. In this paper, the layout of a CRCP test section with BFRP bars constructed on G330 National Road in Zhejiang Province, China, is presented. An analytical model is proposed to predict the crack behavior of CRCP with BFRP reinforcement, with the predicted results are compared to field-measured ones. A sensitivity analysis of the BFRP design parameters on the crack spacing and crack width is conducted as well. The results show that the mean values for field-measured crack spacing and crack width are 4.85 m and 1.30 mm, respectively, which are higher than the results for traditional CRCP with steel due to the lower elastic modulus of BFRP. The analytical predictions agree reasonably well with the crack survey results. The higher the elastic modulus of BFRP, the reinforcement content (with both BFRP spacing and diameter related), and the bond stiffness coefficient between the BFRP and concrete, the less the crack spacing and crack width will be. Given the same or similar reinforcement content, a lower diameter with a smaller spacing is recommended because of its contribution to a smaller crack spacing and width.

Theoretical Analysis of Reinforced Beams of UHTCC

2018 ◽  
Vol 878 ◽  
pp. 18-22
Author(s):  
Hua Qiang Yu
Keyword(s):  
Crack Width ◽  
Approximate Formula ◽  
Crack Spacing ◽  
Cementitious Composite ◽  
Reinforcement Effect ◽  
Ordinary Concrete ◽  
High Toughness ◽  
Reinforced Beams ◽  
New Type ◽  
Average Crack

UHTCC (Ultra High Toughness Cementitious Composite) is a new type of material which is widely used in this study. It is a kind of cement-based material with very good toughness. It is effective to improve the performance of damaged reinforced concrete and improve its durability. UHTCC is widely used in the reinforcement of concrete structures. There is no clear and effective method for calculating it. There is an approximate formula for the crack width of ordinary concrete. The concept of an average crack spacing is used in the derivation of the formula. The limit of UHTCC for cracks can be measured by the concept of average crack spacing. According to the obtained crack width limit, the reinforcement effect of UHTCC can be shown.

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