Numerical and analytical study of rate effects on drilling forces under bottomhole pressure

The scope of this paper is to investigate rate effects on rock cutting process at bottomhole pressure. The solution of the cutting problem is derived in the framework of the theory of poroelastoplasticity. The problem is firstly solved analytically using some assumptions derived from the literature review. Then, a numerical resolution of the fully coupled problem is performed based on the finite element method. These two different approaches show that pore pressure in shear-dilatant rocks decreases as a function of the cutting velocity depending on rock permeability and interstitial fluid properties. Pore pressure change has a hardening effect leading to an increase of the rock drilling resistance.