In the modelling of a burst test of a buried pipeline under compression it is necessary to take into account for the backfill constraint due to soil surrounding the pipe. The backfill influence on crack propagation can be effectively accounted by means of a simplified mechanical model for the soil; this is done using the reduction to lumped masses, with imposed slip directions, linked by non linear springs, whose stiffness is achieved from a given constitutive law. The verification of the soil parameters is performed by means of a numerical procedure which applies flaps displacements reconstructed by integration of strain gauge measurements during a full scale fracture propagation test. The present work deals with the constraint effect of soil (soil backfill) on a highly pressurised buried pipe interested by ductile fracture propagation on its upper generatrix. The study of this effect is important to make a realistic simulation of the pipe behaviour with the aim to obtain reliable predictions in terms of crack arrest capability of a gas transportation line. The backfill model is based on a simple package of soil elements having concentrated mass and stiffness. Some experimental evidences are used to check the basic assumptions and to establish the degree of accuracy of results. The model developed, even if some aspects need future investigations, has a sufficient accuracy for the implementation inside a more general finite element code to study ductile fracture propagation in gas pipelines. In that case further models are included especially for gas discharge through the crack and for ductile fracture propagation.
Numerical model of the backfill constraint effect during fracture propagation on buried large diameter gas pipelines
Numerisches Modell der Zwangwirkung der Hinterfüllung während der Bruchausbreitung in unterirdischen Gasfernleitungen hohen Durchmessers
2000
15 Seiten, 14 Bilder, 10 Quellen
Aufsatz (Konferenz)
Englisch
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