Stability of drilling rigs moving on a weak subsoil. Theoretical formulation and selected case studies.

Highlights • A novel, theoretical 3D model of a drilling rig – subsoil system is proposed. • Subsoil-drilling rig interaction characteristics are obtained with aid of 3D FEM. • Practical examples concerning stability of a drilling rig are given. • A brief state-of-the-art report is included. Abstract The main goal of the article is the theoretical formulation and elaboration of a numerical solution to the stability problem with heavy drilling rigs moving on weak subsoil. All static loadings and inertia effects caused by the machines' movement, as well as geometrical imperfections, are taken into account. The machine-subsoil interaction problem is solved using the ZSoil software [13]. In the programme, the subsoil and working platform are modelled as an elastic-plastic continuum, using fully drained conditions for the working platform and undrained conditions for the weak subsoil, while the machine base is treated as a quasi-rigid body. A theoretical mechanical model and algorithms to design working platform, for a given machine with its movement parameters (velocities and accelerations), or to assess limit conditions on machine movement, for a given subsoil properties, are elaborated. Two selected case studies are analysed, to prove the robustness of the proposed approach. [ABSTRACT FROM AUTHOR]