摘要: |
The need for information on the performance of large buried conduits was the catalyst for an instrumentation program for the Ohio Department of Transportation. A corrugated steel, multiplate keyhole-slotted conduit 4.4 m in diameter, 249 m long, under 20 m of earthfill was instrumented to obtain readings of earth pressures and measurements of changes in diameter as well as slip between the conduit plates. Eight pneumatic total pressure cells were installed at the springline with three more placed just above the crown. Near-field stresses have deviated by 15 to 40% from stresses calculated free of arching effects. Stresses in most cells have been decreasing slowly, indicating stress relief in the long-term behavior of the conduit. Diametral deformation stations were established at 7.62-m intervals throughout the length of the conduit. Four readings of diameter were made at each station (vertical, horizontal, and the two 45-degree diagonals). Excellent agreement with expected behavior of conduit geometry has been observed. A significant amount of plate slip occurred during the first few days following construction of the fill, but slippage has slowed with time. Measurement of earth pressures near the conduit wall has shown that slotted joints do permit greater burial depths than would conventional bolted joints. |