Laboratory Study of Stick-Slip Behavior and Deformation Mechanics of Subglacial Till
Summary
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). Figures are available as Encapsulated Postscript (.eps) files.
Citing These Data
The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.
The following example shows how to cite the use of this data set in a publication. List the principal investigators, year of data set release, publisher: NSIDC, and digital media.
Anandakrishnan, S., and C. Marone. 2010. Laboratory Study of Stick-Slip Behavior and Deformation Mechanics of Subglacial Till. Boulder, Colorado, USA: National Snow and Ice Data Center. http://dx.doi.org/10.7265/N5WH2MX7.
Overview Table
| Category | Description |
|---|---|
| Data format | Data are in ASCII text (.txt) format. |
| Spatial coverage and resolution |
Experiments were conducted in a laboratory setting, with till samples collected from the following locations. Matanuska Glacier Till Sample 2: Matanuska Glacier Till Sample 4: Caesar Till: |
| Temporal coverage and resolution | Laboratory experiments were performed from 2004 to 2007. |
| File naming convention | p1025.txt p603.txt |
| File size | Files range in size from 250 KB to 3438 KB. |
| Parameter(s) | Shear Stress Shear Strain Shear Strength Layer Thickness Time |
| Procedures for obtaining data | Data are available via FTP. |
Table of Contents
- Contacts and Acknowledgments
- Detailed Data Description
- Data Access and Tools
- Data Acquisition and Processing
- References and Related Publications
- Document Information
1. Contacts and Acknowledgments
Investigator(s)
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
Technical Contact
NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449 USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org
Acknowledgements
This research was supported by NSF OPP grant 0440523.
2. Detailed Data Description
Format
Data are in ASCII text format (.txt). Figures are available in Encapsulated Postscript (.eps) format.
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.
| 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. |
File Naming Convention
Files are named according to the following convention and as described in Table 2:
pXXXsYtrZ.bin
Where:
| Variable | Description |
|---|---|
| pXXX | Experiment number, where XXX indicates a number between 491 and 1261 (Experiment numbersin this data set are not sequential.) |
| s | Contact area size: Lowercase "s" indicates a 5cm x 5cm contact area. Uppercase "S" indicates a 10cm x 10cm 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.
File Size
Files range in size from 250 KB to 3438 KB.
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
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
| 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 |
3. Data Access and Tools
Data Access
Data are available via FTP.
Volume
The total volume of this data set is 20.5 MB.
Software and Tools
Data are accessible using spreadsheet software. Image files may require image processing software.
Related Data Collections
4. Data Acquisition and Processing
Theory of Measurements
For detailed information on the experimental setup, data processing, and potential errors, see Rathbun et al., 2008.
5. References and Related Publications
Haefner, R. J. (Ed.) 1999. A conference on fractured glacial tills: Field trip guide to selected fractured glacial till sites and soils in central Ohio, paper presented at Water Management Association of Ohio Spring Conference on Fractured Glacial Tills, U. S. Geol. Surv., Columbus, Ohio, 10 May 1999 .
Rathbun, A. P., C. Marone, R. B. Alley, and S. Anandakrishnan. 2008. Laboratory study of the frictional rheology of sheared till. J. Geophys. Res., 113, F02020, doi:10.1029/2007JF000815.
The following related documents are available
| Document | Description | URL |
|---|---|---|
| Antarctic Glaciological Data Center (AGDC) | Data Center Web site | http://nsidc.org/agdc/ |
6. Document Information
Acronyms
The following acronyms are used in this document.
| Acronym | Description |
|---|---|
| EPS | Encapsulated Postscript file |
| FTP | File Transfer Protocol |
| MPa | Megapascals |
| NSIDC | National Snow and Ice Data Center |
| URL | Uniform Resource Locator |
Document Creation Date
12 April 2010
Document URL
http://nsidc.org/data/docs/agdc/nsidc0460_rathbun/index.html
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