An analytical method for strength verification of buried steel pipelines at normal fault crossings

Abstract

The complex problem of strength verification of a buried steel pipeline crossing the trace of a normal active fault is treated analytically, and a refined methodology for the calculation of the axial and bending pipeline strains is presented. In essence, the proposed methodology extends the analytical methodology originally proposed by Karamitros et al. [1] for the simpler case of strike-slip fault crossings. The modifications introduced to the original methodology are first identified, following a thorough examination of typical results from advanced 3D nonlinear numerical analyses, and consequently expressed via an easy to apply solution algorithm. A set of similar numerical analyses, performed for a wide variety of fault plane inclinations and intersection angles between the pipeline axis and the fault trace, is used to check the accuracy of the analytical predictions. Fairly good agreement is testified for pipeline strains up to 1.50–2.00%. It is further shown that, although the methodology proposed herein applies strictly to the case of right intersection angles, it may be readily extended to oblique intersections, when properly combined with existing analytical solutions for strike-slip fault crossings (e.g. [1]).