Impact forces of submarine landslides on suspended pipelines considering the low-temperature environment

Submarine pipelines in deep-water oil and gas developments are highly vulnerable to the threat of submarine landslides, which results in enormous, inestimable losses. Currently, the numerical method of computational fluid dynamics (CFD) is often employed to predict the impact of landslides on pipelines. However, a constitutive model based on artificially configured materials instead of natural marine clay is used for the numerical studies. In particular, the effect of the low-temperature environment of the seabed on the behavior of marine clay has not been considered. In this paper, a low-temperature rheological model was established by conducting rheological tests of submarine mud flows from the northern continental slope of the South China Sea and introduced into the CFD numerical simulation. The impact of mud flow on suspended pipelines was then systematically numerically calculated. The effect of the peak and stable loads on the impact force calculation is considered, and the average rate of change of the two quantities can reach 27.9%. Compared with the drag force and lift force of a mud flow impact on pipelines at 22 degrees C, those at 0.5 degrees C are increased by 26.0% and 70.3%, respectively. Finally, calculation equations of the peak and stable values of the impact force are established, which can provide a scientific basis for the engineering design of pipelines.