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RESULTS AND RECOMMENDATIONS OF FORENSIC INVESTIGATION OF THREE FULL-SCALE GRS ABUTMENT AND PIERS IN DENVER, COLORADO.
| 题名： | RESULTS AND RECOMMENDATIONS OF FORENSIC INVESTIGATION OF THREE FULL-SCALE GRS ABUTMENT AND PIERS IN DENVER, COLORADO. |
| 作者： | Abu-Hejleh-N; Zornberg-JG; Outcalt-W; McMullen-M |
| 关键词： | Backfill-soils; Bearing-capacity; Block-facing; Block-to-block-connection; Blocks-; Bridge-abutments; Bridge-piers; Construction-damage; Cracking-; Deformation-; Denver-Colorado; Failure-; Forensic-investigation; Geotextiles-; Load-tests; Prototype-tests; Reinforced-earth; Soil-compaction; Tensile-strength; Tension-tests; Weather-conditions |
| 摘要： | In 1996, a full-scale geotextile-reinforced soil (GRS) bridge abutment and two bridge piers with block facing were constructed in the Havana Maintenance Yard in Denver, Colorado. The abutment and outer GRS pier were load tested to demonstrate that GRS abutments and piers with block facing are viable alternatives to conventional bridge piers and abutments. Four to six months after the surcharge load was placed, excessive movements of the top several layers of the outer pier structure and severe cracking of the block facing were noticed. The toppling failure of the upper four block layers of the outer pier was deemed imminent and, consequently, the structures were dismantled. This report summarizes the measured in-situ conditions and characteristics of the structures' materials (backfill, blocks, and geotextile fabric) after almost three years of being in place and identifies potentially relevant causes for the excessive deformation and cracking of the outer pier structure. Results of 27 out of 28 soil density tests indicate the backfill compaction level for the Havana GRS structures was below standard specifications (the average measured relative compaction was 88.3%). Also, relative compaction was variable (ranging 74% to 97%) and particularly low (88.3%), especially close to the facing (average of 86.6%). Results of 128 wide-width tensile tests, conducted on geotextile sheets, indicated only a small loss of geotextile tensile strength (5.3%), which was attributed primarily to construction damage. Construction damage contributes to geosynthetic material deterioration and should be minimized. The block facing of the outer pier showed heavy external and internal damage in the middle zone. The facing experienced its largest movements in the upper four block layers, which decreased with the depth to become negligible in the bottom layers. The excessive deformations in the upper zone of the pier were evidence of a bearing capacity problem. Both the results of forensic investigation and simplified facing connection stability analysis indicate that layers 25 to 38 of the outer pier failed in meeting the serviceability block-to-block connection requirements. Potential reasons for the observed excessive deformation and cracking of the Havana outer pier are: high surcharge load applied to a limited surface area of a slender pier, low and variable backfill compaction level, low facing connection strength and reinforcement pullout resistance in the upper zone of the pier, weak blocks, and seasonal changes of temperature and moisture. GRS abutments and piers, constructed using closely spaced and high-strength geosynthetic reinforcements, well-compacted quality granular backfill, and strong blocks are vW600 |
| 总页数： | 2001/06. pp84 (17 Phot., 14 Fig., 5 Tab., 12 Ref., 1 App.) |
| 报告类型： | 科技报告 |
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