The development of bearing capacity index. Testing the deflection ratio hypotlesis

Kantavuustunnusluvun kehittaminen. Taipumasuhde-hypoteesin testaus

Road surface deflection under dynamic loading is measured using the falling weight deflectometer (FWD). Various indices (spring bearing capacity, bearing capacity ratio, deflection differences) are calculated from the measured deflections to depict the road structural condition. However, the current indices are not considered reliable, therefore the use of deflection data in road maintenance management is scarce.The measurement programs are being cut down, which creates a need for developing a new bearing capacity index based on other condition data than the FWD, e.g. surface profile and surface defects. The objective was to develop the calculation principles for a bearing capacity index based on measurements done using the road surface monitoring (RSM) vehicle and automated road surface distress survey.Such an index would relate the current structural condition of the road to the initial condition. Based on the analytical theory, a research hypothesis was formulated that the deflections in the loaded area (wheel paths) are greater than in the unloaded area (between wheel paths). From a networ k of observation roads,fifty-five meter sections were selected for analys is. The FWD measurements were carried out along two longitudinal lines, o ne in the outer wheel path and the other between wheel paths, using a 25m spacing between the measurement points. In addition, 36 of the sections w ere measured using the automated road surface distress survey. These data were combined with the data derived from the condition data bank. Based on the analysis of these data, the phenomena relating to the selected researc h hypothesis could not be observed, i.e. deflections in the outer wheel pa th are not greater than between the wheel paths. Neither could a correlati on be found between other condition indicators and the ratio of deflections ratio in outer wheel path and between the wheel paths. Thus the calculation principles for a bearing capacity index could not be developed. Based on this and previous studies done for the Finnish Road Administration during the last ten years, no clear correlation between surface deflections measured using the FWD and other condition indicators exists. Therefore, FWD measurements at network level could be altogether stopped, and the resources allocated for more detailed measurements at the project level, focusing on problematic sections found using e.g. the RSM vehicle and the automated road surface distress survey. This report may be found at http://alk.tiehallinto.fi/julkaisut/pdf/3201032-v-voh_kantavuustunnusluku.pdf

• Record URL:
  http://alk.tiehallinto.fi/julkaisut/pdf/3201032-v-voh_kantavuustunnusluku.pdf
• 
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/9789518038293
• Authors:
  • SPOOF, H
  • RUOTOISTENMAKI, A
• Publication Date: 2007

Language

• Finnish

Media Info

• Pagination: 31p+app
• Serial:
  • TIEHALLINNON SELVITYKSIA, FINNRA REPORTS
  • Volume: 3201032
  • Issue Number: 6/2007
  • Publisher: Finnish Road Administration
  • ISSN: 1457-9871

Subject/Index Terms

• TRT Terms: Bearing capacity; Falling weight deflectometers; Loads; Measurement; Roads; Surfaces
• Geographic Terms: Finland
• ITRD Terms: 3085: Bearing capacity; 6187: Deflectograph; 8035: Finland; 2755: Highway; 5567: Load; 6136: Measurement; 6438: Surface
• Subject Areas: Highways; Maintenance and Preservation; I60: Maintenance;

Filing Info

• Accession Number: 01043676
• Record Type: Publication
• Source Agency: TRL
• ISBN: 978-951-803-829-3
• Files: ITRD
• Created Date: Mar 9 2007 8:07AM