ABSTRACT
Pipeline replacement ‘on line’ has been practiced for many years using a technique known as pipe bursting. One of the most important considerations for the design of a pipe bursting operation is the degree of ground displacement caused as a result of the process. Pipe bursting typically creates a residual outward pattern of displacements, although the temporary displacements can be considerably larger than the residual displacements. The ground movements during construction will often, therefore, provide the worst case for design. There is also the possibility of residual ground settlements if the works are carried out in loose granular soils or in soft cohesive deposits in which positive pore water pressures are generated. The pattern and magnitude of displacements has been shown by the two senior authors to be dependent on several parameters following a comprehensive programme of laboratory modelling and field trials. Parallel work by Advantica Technologies Limited (formerly BG Technology/British Gas) has resulted in the publication of tables and charts detailing ‘safe working distances’ for pipe bursting in relation to cast iron gas mams. Prediction of these displacements is evidently vital for the safe operation of these replacement techniques.
A newer technique that has been proposed for ‘on line’ replacement is pipe splitting. Prior to its adoption, it is important that differences in the patterns of displacement to those of pipe bursting are known. To this end, Advantica is currently sponsoring a programme of full-scale laboratory model testing of pipe splitting operations at the University of Birmingham. This paper aims to describe the inherent differences of pipe splitting operations, detail the programme of tests and report the results of tests in sand.
