Effect of High Groundwater on Flexible Culvert Response to Truck Loading

Design of flexible culverts to support vehicle loads is routinely based on soil behaviour where the groundwater table is assumed to be at or below the culvert invert (so that pore pressures are negligible in the backfill beside and above the pipe). To investigate the potential limitations of this assumption, a new facility has been developed at Queen’s University which permits high groundwater experiments to be conducted on corrugated steel culverts (where groundwater can be controlled within the test chamber). The effects of high groundwater (like those during a storm) are being studied, where pore pressures reduce the effective stresses and modulus of the soil near the pipe structure, which change the soil–pipe interaction. The ability to introduce and control groundwater is also allowing experiments studying soil erosion beside the test pipe, as a result of inflows through perforations in the pipe walls (due to simulated corrosion). The facility is being used to study pipe responses to vehicle loading (represented by a pair of wheels on a truck axle) under normal groundwater conditions where the water table is at or below the pipe invert, under high groundwater conditions (where the groundwater level is near the ground surface), and after the development of soil erosion. These studies are of importance to highway engineers responsible for assessing culvert capacity and setting load ratings.