scholarly journals The propagation saw test: slope scale validation and alternative test methods

2012 ◽  
Vol 58 (208) ◽  
pp. 407-416 ◽  
Author(s):  
Cameron K.H. Ross ◽  
Bruce Jamieson
Keyword(s):  
Scale Validation ◽  
Fracture Propagation ◽  
Fracture Initiation ◽  
Test Methods ◽  
Alternative Methods ◽  
Column Length ◽  
Layer Depth ◽  
Weak Layer ◽  
Predictive Skill ◽  
Alternative Test

AbstractThe propagation saw test (PST) is a recently developed snowpack test that enables assessment of the fracture propagation propensity of selected persistent weak-layer and slab combinations, which are known to release dry-slab avalanches. In this paper, we assess the slope- scale accuracy of the standard PST method at validated sites of observed weak-layer fracture initiation, with or without propagation. We also report on experiments with alternative test methods and varying saw thicknesses. Results show the standard PST method is comparably accurate to other common snowpack tests in predictive skill when predicting propagation propensity on the slope scale. Although a slight but significant dependence on saw thickness was found, it did not affect the interpretation in our validation study. Alternative methods such as scaling the test column length with weak-layer depth or leaving the upslope end of the column attached to the surrounding snowpack did not improve slope- scale accuracy and these tests were often more difficult to interpret.

Review of Fracture Control Technology for Gas Transmission Pipelines

2014 ◽  
Author(s):  
Xian-Kui Zhu
Keyword(s):  
Ductile Fracture ◽  
Fracture Propagation ◽  
High Strength ◽  
Fracture Initiation ◽  
Alternative Methods ◽  
Opening Angle ◽  
Pipeline Steels ◽  
Control Plan ◽  
Fracture Control ◽  
Arrest Toughness

A fracture control plan is often required for a gas transmission pipeline in the structural design and safe operation. Fracture control involves technologies to control brittle and ductile fracture initiation, as well as brittle and ductile fracture propagation for gas pipelines, as reviewed in this paper. The approaches developed forty years ago for the fracture initiation controls remain in use today, with limited improvements. In contrast, the approaches developed for the ductile fracture propagation control has not worked for today’s pipeline steels. Extensive efforts have been made to this topic, but new technology still needs to be developed for modern high-strength pipeline steels. Thus, this is the central to be reviewed. In order to control ductile fracture propagation, Battelle in the 1970s developed a two-curve model (BTCM) to determine arrest toughness for gas pipeline steels in terms of Charpy vee-notched (CVN) impact energy. Practice showed that the BTCM is viable for pipeline grades X65 and below, but issues emerged for higher grades. Thus, different corrections to improve the BTCM and alternative methods have been proposed over the years. This includes the CVN energy-based corrections, the drop-weight tear test (DWTT) energy-based correlations, the crack-tip opening angle (CTOA) criteria, and finite element methods. These approaches are reviewed and discussed in this paper, as well as the newest technology developed to determine fracture arrest toughness for high-strength pipeline steels.

scholarly journals Towards a field test for fracture propagation propensity in weak snowpack layers

2006 ◽  
Vol 52 (176) ◽  
pp. 164-168 ◽  
Author(s):  
Dave Gauthier ◽  
Bruce Jamieson
Keyword(s):  
Field Test ◽  
Fracture Propagation ◽  
Field Tests ◽  
Fracture Initiation ◽  
Bimodal Distribution ◽  
Test Method ◽  
Flexural Wave ◽  
Weak Layer ◽  
Columbia Mountains ◽  
Initiation And Propagation

AbstractSlab avalanche release requires fracture initiation and propagation in a weak snowpack layer. While field tests of weak-layer strength are useful for fracture initiation, the challenge remains to find a verified field test for fracture propagation. We introduce the two current versions of a field test for fracture propagation propensity, and report results of testing conducted in the Columbia Mountains of British Columbia, Canada, during the winter of 2005. By extending the column of a stability test approximately 3 m in the downslope direction, the test method allows for the development of a flexural wave in the slab, and thereby maintains the contribution of this wave and the associated weak-layer collapse to the fracture process. Fracture lengths collected on a day and location where the propagation propensity of the snowpack was locally high show a bimodal distribution, with approximately 50% of observed fractures similar to those collected in stable snowpacks, and approximately 50% with much longer fracture lengths.

The Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM): A Review of the ICCVAM Test Method Evaluation Process and Current International Collaborations with the European Centre for the Validation of Alternative Methods (ECVAM)

2002 ◽  
Vol 30 (2_suppl) ◽  
pp. 23-32 ◽  
Author(s):  
William S. Stokes ◽  
Leonard M. Schechtman ◽  
Richard N. Hill
Keyword(s):  
International Adoption ◽  
Evaluation Process ◽  
Test Methods ◽  
Test Method ◽  
Alternative Methods ◽  
Laboratory Animals ◽  
European Centre ◽  
The Usa ◽  
Alternative Test

Over the last decade, national authorities in the USA and Europe have launched initiatives to validate new and improved toxicological test methods. In the USA, the Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM), and its supporting National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM), were established by the Federal Government to work with test developers and Federal agencies to facilitate the validation, review, and adoption of new scientifically sound test methods, including alternatives that can reduce, refine, and replace animal use. In Europe, the European Centre for the Validation of Alternative Methods (ECVAM) was established to conduct validation studies on alternative test methods. Despite differences in organisational structure and processes, both organisations seek to achieve the adoption and use of alternative test methods. Accordingly, both have adopted similar validation and regulatory acceptance criteria. Collaborations and processes have also evolved to facilitate the international adoption of new test methods recommended by ECVAM and ICCVAM. These collaborations involve the sharing of expertise and data for test-method workshops and independent scientific peer reviews, and the adoption of processes to expedite the consideration of test methods already reviewed by the other organisation. More recently, NICEATM and ECVAM initiated a joint international validation study on in vitro methods for assessing acute systemic toxicity. These collaborations are expected to contribute to accelerated international adoption of harmonised new test methods that will support improved public health and provide for reduced and more-humane use of laboratory animals.

scholarly journals Snowpack tests for assessing snow-slope instability

2010 ◽  
Vol 51 (54) ◽  
pp. 187-194 ◽  
Author(s):  
Jürg Schweizer ◽  
J. Bruce Jamieson
Keyword(s):  
Fracture Propagation ◽  
Fracture Initiation ◽  
Test Methods ◽  
Slope Instability ◽  
Test Reliability ◽  
Field Observations ◽  
Average Accuracy ◽  
Comparable Accuracy ◽  
Sensitivity Specificity ◽  
Shear Frame

AbstractInformation on snowpack instability is crucial for assessing avalanche risk in backcountry operations as well as for operational forecasting of the regional avalanche danger. Since slab avalanche release requires both fracture initiation and fracture propagation in a weak snowpack layer, field observations should ideally provide reliable information on the probability or propensity of both fracture processes. Even simple field observations that do not require digging a snow pit can provide useful information. Traditional snowpack tests include the shovel shear test, the shear frame test, the compression test (CT) and the rutschblock test (RB). Interpretation of the test results for the CTand RB has been improved by considering the appearance or type of the fracture in addition to the score. More recently, two tests have been developed that focus on fracture propagation rather than initiation: the extended column test (ECT) and the propagation saw test (PST). We compare the sensitivity, specificity and unweighted average accuracy of various stability tests. Comparative studies indicate that the RB, ECT and PST have comparable accuracy. For most test methods the unweighted average accuracy of a single test was 70–90% depending on the dataset. Test methods such as the RB, ECT and PST, which fracture an area large enough to include fracture propagation, are generally more accurate than test methods that fracture smaller areas (e.g. the CT). The threshold-sum method was also less accurate. Even with very experienced observers for the RB, ECT and PST an error rate of at least about 5–10% has to be expected. Performing a second, adjacent test on the same slope improves test reliability.

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