In the foregoing paper we have proposed a strategy for soil modelling based on the discrete approach. By considering the soil as an assembly of rigid disks we have developed a local model. The model concentrates at the contact level between the disks the real mechanical behaviour of the soil. For this purpose suitable contact models have been developed, where specific elasto-plastic laws have been implemented in the node-to-segment contact formulation. In this second part after investigating the mechanical behaviour of the local model we reproduce, with an assembly of disks (global model), the real behaviour of stiff soils and rocks under standard loading paths. The change of scale from the local to global level is carried out through dimensional analysis. The behaviour of different soils is simulated by regular and irregular monodisperse packings of disks and compared with real laboratory tests.
The unknown interaction of the cutting tools with geological settings represents an interesting problem for the excavation machinery industry. To simplify the non-linear aspects involved in the numerical analysis of such phenomena a strategy for an accurate soil modelling has to be defined. A possible approach is the discrete one, by considering the soil as an assembly of rigid spheres. In this work this strategy is adopted. The basic idea is to concentrate at the contact level between the spheres the real mechanical behaviour of the soil. For this purpose suitable contact models have been developed, where specific elasto-plastic laws have been implemented in the node-to-segment contact formulation. The framework for the plastic behaviour consists of a failure criterion, a onedimensional, rate-independent elasto-plastic flow rule for the normal and the tangential force and a non-linear yield criterion. The final aim of this paper is to develop mechanical models to study the behaviour of stiff soils and rocks under different loading conditions.
The interaction of the cutting tools with different geological settings determines a different wear and consequently different economical costs for the excavation. We apply here a strategy for soil modelling which is based on discretization of the continuum with rigid disks and suitable contact models. We concentrate at contact level the real mechanical behaviour of the soil. In order to carry out this strategy a “micro” and a “macro” level are established. This paper focuses on the micromechanical model.
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