On the issue of damping external loads of mine racks

Abstract

The vulnerability of the main structural elements of rock liningsto external short-term and long-term loads is an important problem in the mining industry. The existing schemes are not designed for the simultaneous perception of compressive, shock and vibration influences. A way to solve this problem is to develop a new structural scheme of the racks, which are the linings' main bearing element. In the article, it is proposed to use multi-layer racks made as a rod covered with layers of plates.This will make it possible to use for damping external loads not only the pliability of the rack as a whole but also the frictional forces between its layers.The acting impact force will be decomposed into compressive and pressing forces. Due to the fact that the action of the external shock load is spent on moving and pressing the layers, its deformations are minimized compared to single-layer monolithic structures.For calculating the arising stresses, it is assumed that the rack plates are hinged at the edges, free along the length of the rack, and are under the joint action of compressive (stretching) forces and tangential forces evenly distributed on all sides of the plate.The article provides a rationale for the prospect of using such multi-layer racks and proposes an algorithm for calculating critical loads and stresses with the derivation of the damping coefficient. This coefficient is determined by the difference between the force of the shock wave and the critical load. The critical force, in turn, is calculated as the difference between the compressive force and the friction force between the layers, corrected for the part of the impact force, which causes stress close to critical in the dangerous middle section of the plate. By the value of the coefficient, it can be judged the effectiveness of the selected structural scheme of the rack.