Plastic Design of Buried Steel Pipelines in Settlement Areas

摘要

Loads acting on buried steel pipelines consist of combinations of internal liquid or gas pressure, earth pressure and temperature differences. Where differential settlements occur along the alignment of a pipeline, the latter is moreover subject to imposed deformations. This occurs more particularly at crossings with dykes, roads and railways. It means that, besides the strength (internal pressure, resistance to earth pressure), the deformation capacity is important. Design methods based on elastic theory have long been used for pipelines. The actual behavior up to failure cannot properly be described by those methods, however. Research has led to the development of a new method of design and analysis based on plastic theory, which does provide a good insight into the actual strength and deformation properties and thus into the actual structural safety available. In many situations the actual strength and actual deformation capacity are found to be considerably greater than can be shown on the basis of an elastic analysis.