Effects of Erosion Void on Deteriorated Metal Culvert before and after Repair with Grouted Slip Liner

A corroded corrugated steel pipe was buried with an erosion void simulated from the haunch to the shoulder on one side. Testing under simulated service loads revealed that the void appeared to compromise the stability of the structure at a load of 87% of the full service load. Changes in curvature under load in the springline adjacent to the simulated erosion void were about 3 times higher than those at the springline with soil support. Compressive wall thrusts were also substantially higher on the side adjacent to the erosion void. The culvert was then rehabilitated using a grouted slip liner. A steel-reinforced high-density polyethylene pipe was used together with low-density, low-strength grout. Stiffness after rehabilitation was enhanced considerably, with diameter changes at full service loads decreased by an order of magnitude. Strains in the corrugated steel pipe were also much lower. Strains measured on the corrugated steel pipe and on the steel ribs of the steel-reinforced polyethylene pipe suggest that below 300 kN, the grout had not fractured, and the steel pipe, grout, and liner within responded as a composite system. Above 300 kN, the grout appears to have fractured, and strains in the steel pipe and liner accelerated with applied load. The ultimate limit state appears to correspond to development of full plastic hinges in the steel ribs of the liner at the crown, the springlines, and the invert. The structural repair based on grouted slip lining was found to be more than adequate, because the force applied to the single axle at the ultimate limit state was well beyond the full factored load requirements for these structures.