Layer-by-layer Cutting of Rocks

摘要

To describe the process of cutting of geomaterials by a two-sided wedge, a rigid-plastic model is considered taking into account the influence the wedge speed has on the cutting force, shear plane orientation, and sizes of sheared pieces. Geomaterials are known to resist tensile and compressive deformation in a different manner, and their compressive strength is higher than the tensile strength approximately by an order of magnitude. In certain conditions of cutting, it is wedge-generated tension that destracts geomaterial, which allows a wedge to be reckoned an energy-optimal tool. Hence, mining and road building machine effectors mostly have the shape of a wedge [1-7]. However, deformation of rock by a horizontally directed wedge is not necessarily the case for a cleavage fracture. Both the normal and shear fractures are possible, depending on geometrical parameters of a wedge, the friction coefficient at the wedge - geomaterial interface, and the sheared layer thickness. The normal fracture takes place when tensile stresses dominate on a shear plane, and the shear fracture arises under compression along the normal to this plane. The wedge speed has a considerable influence on the mode of failure of a sheared layer of rock [1 - 7], and it is necessary to take into account the rate with which effectors and material fractured interact in order to design highly productive mining and road building machines.