ROCK ANCHORS - STATE OF THE ART. PART 3: STRESSING AND TESTING
The acceptance testing of production anchors is discussed, and comments are are made on the long-term monitoring of selected production anchors. It is stressed that the testing procedure must yield a measured safety factor as determined by overloading for a short period. To check the measured performance against that predicted by calculation, it is essential that a load-extension graph be plotted for each anchor. Also, an attempt must be made to obtain an indication of fixed anchor movement, since this will enable the assessment of the component of permanent displacement of the anchor with time. It is noted that while load- extension boundary lines are favored in practice, care and attention is required in interpretation. To alleviate problems in interpretation, it is recommended that all production anchors should be subjected to at least one stage of cyclic preloading. Attention should then be focussed on the load- extension plots of the second and any subsequent load cycles from which most of the initial non-recoverable movements have been removed. For economic as well as operational reasons, the time involved for the stressing and control of anchors on a construction site should be minimized. Field experience indicates that prestress losses may be significant in heavily weathered rock or fractured rock with clay infill. It is noted that only when creep losses are monitored over long periods for a variety of anchor loads and geometries and for a wide range of classified rock types, will an accurate predictive capacity be available.
- Find a library where document is available. Order URL: http://worldcat.org/issn/00174653
- This is the second section of this article; the first appeared in the March 1976 issue, pp. 20-29, and the third is published in the May 1976 issue.
Foundation Publications Limited7 Ongar Road
Brentwood CM15 9AU, Essex, England
- Littlejohn, G S
- Bruce, D A
- Publication Date: 1976-4
- Features: Figures; Tables;
- Pagination: 4 p.
- GROUND ENGINEERING
- Volume: 9
- Issue Number: 3
- Publisher: EMAP CONSTRUCT LIMITED
- ISSN: 0017-4653
- TRT Terms: Acceptance tests; Creep; Deflection; Dislocation (Geology); Forecasting; Loads; Monitoring; Oversize loads; Prestressing; Rocks; Safety factors; Stresses; Weathered rock
- Uncontrolled Terms: Anchors; Overloads; Prestress loss; Stressing
- Subject Areas: Geotechnology; Highways; Safety and Human Factors;
- Accession Number: 00141862
- Record Type: Publication
- Report/Paper Numbers: Analytic
- Files: TRIS
- Created Date: Jan 16 1977 12:00AM