The Performance of Reinforced Concrete Pipe Joints under Differential Ground Settlement

Abstract

Leakage from reinforced concrete pipe joints has negative environmental impacts and can compromise the sewer or culvert’s service life. Pipes can fracture, corrode, rotate, experience joint pullout, and potentially undergo damage during their installation – leading to leakage into or out from the pipe. Reinforced concrete pipes are a common pipe used for waste and storm water transmission and have been proven to be a durable, easily constructed pipe choice throughout modern history. Reinforced concrete pipelines utilize gasketed bell and spigot joints, forming a push fit joint. Joints allow a pipe to accommodate some deformations while maintaining functionality, however, joints also form a point of weakness at which the sealing properties can be compromised with permanent ground deformation. This research project examines 600 mm internal diameter reinforced concrete pipes for joint capacity and response to imposed demands. The key objective of the research was to quantifying rotations and shear forces acting across the joints, as these demands are not readily used in the design of reinforced concrete pipes. Two, multi-segmented pipelines were used for experimentation in buried and unburied environments. Tests were conducted in the Split Box and Joint Articulation Frame at Queen’s University to impose controlled distortions to the pipe joints and barrels. The Split Box was used to subject a three-segment pipeline to a normal fault as a proxy for various forms of permanent ground settlements. The pipe, under an external pressure of 45 kPa, did not leak at a maximum fault offset of 150 mm, however, peak demands were quantified as 2.66 degrees and approximately 0.6 kN of shear force. Local shear force across the joint resulted from rotation rather than shear displacement. The Joint Articulation Frame was used to induce rotation and shear force in the joint of a two-segment pipeline at different external pressures. Pure rotation and shear experiments were conducted in the work to define the leakage limits. The rotational serviceability limit was found to be between 4.8 and 5.2 degrees. Shear limits were not isolated due to equipment limitations but points of successful joint function below the leakage limit were revealed. Simple joint capacity envelopes were developed, which indicate demand combination ranges that yield acceptable joint performance.