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Data Set ID:
NSIDC-0460

Laboratory Study of Stick-Slip Behavior and Deformation Mechanics of Subglacial Till, Version 1

This data set includes the results of laboratory experiments examining the constitutive properties of subglacial till, under dynamic stressing. The data include the results of shear strain and stress experiments. Testing was carried out in a servo-controlled biaxial shear device under controlled temperature and stress conditions, allowing both sliding and microstructural processes to be studied in detail. Till samples were collected from Matanuska, Alaska and from Caesar till at the Laurentide Ice Sheet.

The data are available via FTP in ASCII text format (.txt).

Geographic Coverage

Parameter(s):
  • Soils > Soil Mechanics
Spatial Coverage:
  • N: 61.781667, S: 61.781667, E: -147.753056, W: -147.753056

  • N: 61.779444, S: 61.779444, E: 147.758889, W: 147.758889

  • N: 40.067222, S: 40.067222, E: -83.006944, W: -83.006944

Spatial Resolution: Not Specified
Temporal Coverage:
  • 1 January 2004 to 31 December 2007
Temporal Resolution: Not specified
Data Format(s):
  • ASCII Text
Platform(s) LABORATORY
Sensor(s): PRESSURE TRANSDUCERS
Version: V1
Data Contributor(s): Chris Marone, Sridhar Anandakrishnan
Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Anandakrishnan, S. and C. Marone. 2010. Laboratory Study of Stick-Slip Behavior and Deformation Mechanics of Subglacial Till, Version 1. [Indicate subset used]. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi: http://dx.doi.org/10.7265/N5WH2MX7. [Date Accessed].

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Detailed Data Description

Format

Data are in ASCII text format (.txt). Figures are available in Encapsulated Postscript (.eps) format.

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File and Directory Structure

Data are available on the FTP site in the ftp://sidads.colorado.edu/pub/DATASETS/AGDC/marone_nsidc_0460/ directory. Within this directory, there is a Microsoft word document, ExperimentTable.doc, that lists the conditions for each experiment in the data set.

Table 1. Directory Description
Directory Description
Creep_Experiments Constant shear stress experiments
Friction_Experiments Constant shear velocity experiments
Figure_Data Data files used to produce the figures in Rathbun, et. al.
Figure_Images Figure image files from Rathbun, et. al., in Encapsulated Postscript (.eps) format.
 
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File Naming Convention

Files are named according to the following convention and as described in Table 2:

pXXXsYtrZ.bin

Where:

Table 2. File Naming Convention
Variable Description
pXXX Experiment number, where XXX indicates a number between 491 and 1261 (Experiment numbers in this data set are not sequential.)
s Contact area size: 
Lowercase "s" indicates a 5 cm x 5 cm contact area. 
Uppercase "S" indicates a 10 cm x 10 cm contact area.
Y Initial layer thickness, in mm
t Till
r Rough boundaries
z Normal stress in MPa
.bin File extension

Example: p490s10tr.5.txt contains data from experiment number p490, with 5 cm x 5 cm contact area, 10 mm layer thickness, till with roughened edges, at 0.5 MPa normal stress.

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File Size

Files range in size from 250 KB to 3438 KB.

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Volume

The total volume of this data set is 20.5 MB.

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Spatial Coverage

These data were collected during laboratory experiments, using till collected from three sites:

Matanuska Glacier Till Sample 2:
Southernmost Latitude: 61°46.907' N
Northernmost Latitude: 61°46.907' N
Westernmost Longitude: 147°45.178' W
Easternmost Longitude: 147°45.178' W

Matanuska Glacier Till Sample 4:
Southernmost Latitude: 61°46.766' N
Northernmost Latitude: 61°46.766' N
Westernmost Longitude: 147°45.537' W
Easternmost Longitude: 147°45.1537' W

Caesar Till:
Southernmost Latitude: 40°4'2" N
Northernmost Latitude: 40°4'2" N
Westernmost Longitude: 83°00'25" W
Easternmost Longitude: 83°00'25" W

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Parameter or Variable

This data set contains the results of laboratory experiments on shear stress and strain. Parameters include shear stress, shear strain, time, and layer thickness. Creep experiments were conducted under controlled shear stress to investigate the time-dependent deformational or creep behavior of till, with an inital layer thickness of 10 mm. Friction experiments were conducted with constant shear velocity, in order to find the shear strength and rate-dependent strength of till.

Parameter Description

Table 3. Parameter Description
Parameter Description
Creep Experiments
Shear Strain Shear strain, controlled in creep experiments.
Shear Stress (MPa) Shear stress, in megapascals (MPa)
Time Time in seconds
Friction Experiments
Rec Record number
Shear_str Shear strength, determined at a constant shear velocity
Shear_stress Shear stress, in megapascals (MPa)
Layer_thick Layer thickness, in micrometers (uM)
Norm_stress Normal stress, in megapascals (MPa)
Time Time in seconds
Friction Friction

Sample Data Record


Sample data record from p538.txt. This sample shows only the first four records in the file.

rec shear_str Shear_stress layer_thick Norm_Stress Time Friction
0 0 0 2005 1.00E-07 1 0
1 0 0 2005 1.00E-07 11 0
2 0 0 2005 1.00E-07 21 0
3 0 0 10997 0.0026697 0 0
 
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Software and Tools

Data are accessible using spreadsheet software. Image files may require image processing software.

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Data Acquisition and Processing

Theory of Measurements

For detailed information on the experimental setup, data processing, and potential errors, see Rathbun et al., 2008.

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References and Related Publications

Contacts and Acknowledgments

Dr. Sridar Anandakrishnan
Department of Geosciences
442 Deike Building
Pennsylvania State University
University Park, PA 16802 
USA

Dr. Chris Marone
Department of Geosciences
536 Deike Building 
Pennsylvania State University
University Park, PA 16802
USA

Acknowledgments: 

This research was supported by NSF OPP grant 0440523.

Document Information

Document Creation Date

12 April 2010

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