Simple analytical models for the J-lay problem

This work deals with deep and ultra-deep waters installation by the so-called ‘‘J-Lay’’ method, which consists in laying submarine pipelines with a straight stinger at near-vertical angles. A hierarchy of simple analytical models is proposed starting from the classical catenary and enriching it to overcome its drawbacks. A novel approach for detecting the boundary-layer phenomenon is proposed, and constitutes the base of two of the developed models. All models are compared with each other and with the results of refined numerical simulations in a case of practical interest. In the considered examples the stiffness of the soil has scarce influence, while the boundary layer phenomenon is very important and detected correctly, both from a qualitative and quantitative point of view, by the second class of proposed models.