Investigation of the Failure of a Concrete-Lined Steel Pipe

Abstract

The present paper documents the failure of a large diameter concrete-lined steel sewage pipe, buried in a clay soil profile. The project consisted of a 3.5 km long gravity pipe in central Israel which failed before being taken into service. The paper reports on the failure of the pipe/trench system. Field and laboratory testing provided significant insight into the probable cause(s) of failure. The basic physical mechanism leading to the failure appears to be related to softening and swelling of the clay subgrade upon saturation. Failure of the pipe system can be attributed to incompatibility between the mechanical behaviour of the pipe and the methodology employed in its design. The study illustrates the effects of a basic design flaw resulting from lack of adherence to well accepted standard engineering practices. In addition, investigation of the failure illustrates the effectiveness of a simple field test as a diagnostic tool to evaluate site conditions.