In this paper, we present a coupled Discrete Element (DE) and Lattice Boltzmann (LB) method to model fluid-solid interactions. This method is applied to study and model a two-dimensional piping erosion through a set-up inspired by the Hole Erosion Test (HET). In this work, we mainly focus on grain detachments under hydraulic loading. Simulation results show that the erosion law classically used in such experiments, can be retrieved with our model. It illustrates that such coupled systems can be investigated with the LB-DE approach developed in this work. This approach is a promising tool which is well designed to perform such investigations at the grain scale