Ring Deflection of Buried Pipe

Abstract

This paper discusses one of the criteria for the structural design of buried pipe: ring deflection or change in diameter (flattening down) of the ring due to compression of the soil. The principal objectives were: the development of a relationship by which ring deflection can be predicted as a function of dimensionless parameters based on soil properties and pipe properties; and, the relationship between cracking of the mortar and ring deflection for the particular pipe tested. Secondary objectives included measurements pursuant to the determination of ring deflection, such as a load‐settlement relationship for the soil and ring stiffness for the pipe. The basic procedure was divided into field and laboratory tests. For field tests, 10‐ft long sections of cement‐mortar lined and cement‐mortar lined and coated pipe and bare pipes were buried under carefully controlled soil conditions and the ring deflection and cracking patterns were observed for various loads and soil types. The laboratory tests were essentially three‐edge bearing tests on 3‐ft pipe sections to determine the ring stiffness and statistically to relate cracking patterns and ring deflections.