Origin of a Clastic Dike at St. Ludger, Quebec: An Alternative Hypothesis

1975 ◽  
Vol 12 (6) ◽  
pp. 1048-1053 ◽  
Author(s):  
John A. Elson
Keyword(s):  
Shear Stress ◽  
Pore Pressure ◽  
Closed System ◽  
Alternative Hypothesis ◽  
Elastic State ◽  
Clastic Dike ◽  
Glacier Ice ◽  
Flame Structures

Structures visible in a recent photograph of a clastic dike protruding downward from 'till' into sand at St. Ludger, Quebec suggest that it may not be till as previously reported, but part of a layer of stony lake clay deposited beneath floating ice. Flame structures and faults indicate that the underlying sand changed from a plastic to an elastic state. Probably a layer of stony lake clay was drawn down into the underlying sand by reduced pore pressure developed in part of a closed system. This occurred when adjacent sand in the system was dilated by the shear stress resulting when floating glacier ice grounded. Glacial thrusting may have provided further intrusive impulse after the initial downward deflection.

scholarly journals Waterways, Ice Permeability at Depth, and Water Pressures at Glacier D’Argentière, French Alps

1983 ◽  
Vol 29 (102) ◽  
pp. 227-239 ◽  
Author(s):  
Didier Hantz ◽  
Louis Lliboutry
Keyword(s):  
Free Surface ◽  
Water Level ◽  
Pore Pressure ◽  
Time Lag ◽  
Extensive Study ◽  
Hot Water ◽  
Clear Cut ◽  
Melt Water ◽  
Glacier Ice ◽  
The Right

AbstractTo clear up the changes which had happened at the subglacial catchment of glacier d’Argentière, an extensive study, with 31 borings and a coring down to the bottom (240 m) was performed in 1979/80, just upstream from the catchment, in an overdeepened area. The behaviour of the water level during boring with a hot water jet, and just after, was different from one bore hole to another, mainly because transient leaks appeared in the walls of bore holes. Next, the water level fluctuated slowly, in the same way in most of the deep bore holes, showing that glacier ice below about 100 m deep is slightly pervious. What is so measured is the pore pressure of water in deep ice. The piezometric gradient between bore holes, and the time lag between fluctuations of water level, which increases with distance from the right bank, shows that there is no waterway at the bottom of the overdeepened area, save at its up-stream end. Most of the melt water must flow between ice and rock along the right bank, its free surface rising by about 150 m during the increased discharge in June. No clear-cut correlation between the bottom pore pressure and the air temperature or the discharge at the subglacial catchment down-stream was found.

scholarly journals Some Comments on Glacier Flow

1950 ◽  
Vol 1 (07) ◽  
pp. 383-388 ◽  
Author(s):  
Richard Finsterwalder
Keyword(s):  
Shear Stress ◽  
Shear Plane ◽  
Critical Value ◽  
Ice Flow ◽  
Crystalline Materials ◽  
Fundamental Point ◽  
Glacier Ice ◽  
Slow Moving ◽  
Glacier Flow ◽  
Streaming Flow

Abstract Drs. Orowan and Perutz have shown that glacier ice does not behave as a viscous fluid but is plastic like all crystalline materials. The present author discusses two observed types of ice flow:—(1) the normal, regular streaming flow in slow-moving glaciers; (2) Block-Schollen * movement in swiftly flowing ice. Mention is made of the shear plane or laminar flow theory of Philipp. lt appears that Orowan s thesis is also applicable to Block-Schollen flow. The author agrees with Orowan on the fundamental point that when ice is subjected to shear stress a critical value of the shear stress exists beyond which the ice alters its consistency. But the author disagrees with Orowan in that he believes that below this critical value ice behaves as a viscous material, and he supports this view by reference to many phenomena, measurements and calculations.

scholarly journals Energy dissipation and liquefaction at Port Island, Kobe

1998 ◽  
Vol 31 (1) ◽  
pp. 33-50 ◽  
Author(s):  
R. O. Davis ◽  
J. B. Berrill
Keyword(s):  
Shear Stress ◽  
Energy Dissipation ◽  
Shear Strain ◽  
Pore Pressure ◽  
Calculation Method ◽  
Horizontal Plane ◽  
Dissipated Energy ◽  
Stress And Strain ◽  
Shear Stress And Strain ◽  
Reclaimed Soils

The Port Island, Kobe downhole records from the Hyogo-ken Nanbu earthquake are analysed to obtain approximate histories of shear stress, shear strain and dissipated energy at a range of depths. Our calculation method relies on measured accelerations in the horizontal plane to produce horizontal components of shear stress and strain using instantaneous modal superposition. A simple dissipated energy-dynamic pore pressure relationship is used to model the development of pore pressure leading to liquefaction. The results show a rapidly developing zone of liquefaction which initiates at a depth of roughly 15 metres in the Port Island reclaimed soils.

Earthquakes as a coupled shear stress-high pore pressure dynamical system

1996 ◽  
Vol 23 (2) ◽  
pp. 197-200 ◽  
Author(s):  
Stephen A. Miller ◽  
Amos Nur ◽  
David L. Olgaard
Keyword(s):  
Dynamical System ◽  
Shear Stress ◽  
Pore Pressure

scholarly journals Characteristics of Bituminous Coal Permeability Response to the Pore Pressure and Effective Shear Stress in the Huaibei Coalfield in China

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Lei Zhang ◽  
Zhiwei Ye ◽  
Mengqian Huang ◽  
Cun Zhang
Keyword(s):  
Shear Stress ◽  
Pore Pressure ◽  
Coal Mine ◽  
Gas Flow ◽  
Bituminous Coal ◽  
Stress Conditions ◽  
Coal Permeability ◽  
Gas Seepage ◽  
Shear Slip ◽  
Huaibei Coalfield

The coal permeability is known to be influenced by the pore pressure and effective stress in coal mines. In this study, the characteristics of the bituminous coal permeability response to the pore pressure and effective shear stress in the Xutuan coal mine in Huaibei Coalfield in China were investigated under different stress conditions. For this purpose, gas seepage tests with various stress levels were conducted via the original gas flow and displacement testing apparatus using bituminous coal samples from the Xutuan coal mine. The pore pressure effect on the permeability under different stress conditions was assessed by varying the pore pressure in coal samples and simulating different in situ stresses. The axial and radial pressures were controlled to study the response of coal permeability to the effective shear stress. The experimental results revealed that with an increase in pore pressure, the permeability of coal in different stress environments firstly drops and then rises. The permeability increased gradually with the effective shear stress, which trend became more pronounced when the effective shear stress exceeded zero. In case of the axial pressure exceeding the radial one, the cross shear slip was observed, for which the permeability of coal samples increased with the effective shear stress. In the opposite case, the separated shear slip was observed, with the reverse trend.

scholarly journals The Creep of NaCl-Doped Ice Monocrystals

1978 ◽  
Vol 21 (85) ◽  
pp. 501-507 ◽  
Author(s):  
N. W. Riley ◽  
G. Noll ◽  
J. W. Glen
Keyword(s):  
Mechanical Properties ◽  
Shear Stress ◽  
Creep Rate ◽  
Sea Ice ◽  
Creep Curves ◽  
Polycrystalline Ice ◽  
Glacier Ice

Abstract Monocrystals of ice grown from NaCl solutions (concentration 5 X 10–4 to 10–2 mol/l) have been tested in creep at —10°C by basal glide. The maximum resolved shear stress ranged from 0.6 to 2.5 bar. The resulting creep curves show a deceleration, that is, the creep rate decreases with time. At the highest concentration the creep is essentially transient; the strain tends to a fixed value. This is unlike the behaviour of similarly orientated monocrystals of pure ice or of ice grown from solutions of other dopants so far reported in the literature. The possible causes for this behaviour are discussed and the implications for the mechanical properties of polycrystalline ice, and in particular sea ice and glacier ice, are described.

scholarly journals Some Observations on the Banding of Glacier Ice

1955 ◽  
Vol 2 (17) ◽  
pp. 502-506 ◽  
Author(s):  
N. Untersteiner
Keyword(s):  
Shear Stress ◽  
Normal Stress ◽  
Maximum Shear Stress ◽  
Stress System ◽  
Outward Appearance ◽  
Glacier Tongue ◽  
Maximum Normal Stress ◽  
Glacier Ice

AbstractThe distribution of fine banding (foliation) on the surface of a flat glacier tongue was studied. The conclusions reached are that fine banding seems to be neither of sedimentary origin nor to be the representation of a straightforward stress system. In the present case, foliation seems to be connected with ice falls.Other bands definitely not belonging to the fine banding system were plotted irrespective of their outward appearance. Statistically, their preferred spacial directions correspond to the directions of either maximum shear stress or maximum normal stress (tension).

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