Forensic investigation of abutment rotation: Compaction overpressure?
Moving Toward Smart, Resilient and Sustainable Bridges, CRC Press, ss.809-814, 2026
- Yayın Türü: Kitapta Bölüm / Araştırma Kitabı
- Basım Tarihi: 2026
- Doi Numarası: 10.1201/9781003778677-95
- Yayınevi: CRC Press
- Sayfa Sayıları: ss.809-814
- Orta Doğu Teknik Üniversitesi Adresli: Evet
Özet
This paper presents a forensic root-cause investigation of abutment rotation and deck-level movement observed before opening to traffic on a newly constructed highway bridge in Qatar. Coordinate surveys showed movement stopping in a slightly tilted equilibrium state. The investigation considered three primary causes: (a) base sliding, (b) settlement at the front of the footing due to a ditch and poor soil conditions, and (c) over-compaction of the abutment infill. Measurements indicated sliding dominated behavior; hand checks showed that lateral earth pressures during compaction exceeded the original design assumptions and caused movement. The root cause was assessed to be compaction-induced lateral pressure, beyond the conventional active earth pressure (Ka) typically assumed for an abutment. Soil-mechanics checks for compaction loading quantified the higher lateral demand and the larger effective moment arm during backfill placed adjacent to the wall. The outcome was abutment sliding+rotation toward the deck and displacement at the bearings/base plates. During backfilling, compaction produces a lateral push greater than the long-term design value. The wall pressure gains moment arm, initiating rotation and may also shift base contact toward the toe. The wall moves slightly away from the backfill, the lateral earth pressure drops toward the active level. Combined with base friction from self-weight, these effects stabilize the system near critical equilibrium (FS ≈ 1.0). A practical protocol for high-fill approaches is proposed: (i) consider additional loading for compaction in design or take precautions during construction such as equipment energy and stand-off distance, with operator training, (ii) baseline tilt/ translation monitoring starting before backfill; (iii) active thresholds/alarms for stability; and (iv) detailing or construction controls that decouple horizontal loads from the abutment where appropriate (e.g., anchor into backfill similar to MSE). This framework might help designers, contractors, and owners prevent similar construction-stage movements and delays in the future.