Geotechnical centrifuge and numerical modelling of buried pipelines

Abstract

Mechanical response of buried pipes subjected to vehicle live loads acting on the ground surface has been exhaustively studied in the past decades. However, it remains an open subject especially for cases where the load is not necessarily positioned over the centre of the crown. Simplifications regarding loading transmission based on the theory of elasticity and the lack of soil–pipe interaction in the analyses have been blamed for possible lack of adherence between the predicted and the observed behaviour of such structures. Herein, both numerical and physical modelling were used to capture the important features of the mechanical behaviour of buried pipelines under live moving surface loads. The physical models were tested under modified gravity in a centrifuge, which allowed the calibration of a three-dimensional numerical finite-element model. Three different models were tested in the geotechnical centrifuge, corresponding to three different cover heights: 1D, 1·5D and 2D, where D is the pipe diameter. The results showed that pipe deformations, caused by live vehicle loads applied at distances greater than twice the diameter of the pipe, are negligible. The diametrical deformations did not exceed the 2% limit suggested by regulation associations. The highest value found in this study was 0·2%.