The effect of radial fins on the uplift resistance of buried pipelines

Abstract

This paper investigates the potential for increasing the uplift resistance of buried pipelines through the addition of radial fins on the pipe circumference. Experiments conducted in loose sand showed that fins extending by 20% of the pipe diameter increase the vertical peak uplift resistance by up to 25%, depending on embedment depth and fin configuration. A limit equilibrium solution – based on known values of peak friction and dilation angles – predicts the uplift resistance within 13% of the measurements. The trends of peak uplift resistance with embedment and fin configuration were also replicated in numerical analyses conducted using a non-associated Mohr–Coulomb soil model. The numerically predicted peak uplift resistances were within 10 and 21% of the experimental values for rough and smooth interfaces, respectively. Soil failure mechanisms from the numerical analyses were broadly consistent with that assumed in the limit equilibrium solution. However, the experimentally observed mechanisms differed subtly, with a limited extent of lifted soil above the pipe and circulatory flow occurring from above to beneath the pipe. This mechanism was approached in the numerical analyses for a smooth interface by specifying a small negative dilation angle, which had minimal effect on the predicted peak uplift resistance.