Effects of Environmental Factors on the Deformation of Bridges Supported by Piles and Geosynthetic Reinforced Soils.

摘要

This study evaluates the behavior of three bridges supported by piles and one by geosynthetic reinforced soils (GRS) by analyzing the effect of service and environmental loading conditions. The pile-supported bridges are located just northeast of Madison, Dane County, Wisconsin, and have different span lengths, pile lengths, and subsurface conditions, but share similar service and environmental loads. The GRS bridge is located south of Bloomer, Chippewa County, Wisconsin, and has different subsurface and environmental conditions with respect to the pile-supported bridges. The behavior of these bridges was analyzed by monitoring their vertical deformations over time and performing numerical analyses. The pile-supported bridges show general deformation trends similar to the temperature changes, contracting and expanding as temperature falls and rises. The GRS bridge is also affected by temperature changes but in a different way, as this bridge crosses a stream. As temperatures fall below the freezing point, the water present in the foundation soil and embankment freezes, causing the soils and structure to heave. As temperatures rise and the soil thaws, settlement occurs as the shear strength and stiffness in the soil decrease due to water content increase. Service loading conditions are found to have a lesser impact on the general behavior of the structures as the deformation versus time results do not show consistent settlement trends. The results indicate that the bridges are performing adequately but environmental loads should be considered while assessing the design and behavior of highway bridges.