Arching Effect Principle and Bottom Effect Principle for Reducing Stripping-to-ore Ratio in Furrow Pits

摘要

This paper introduces space-time principles for reducing stripping-to-ore ratio in furrow pits put forward by the first author. The time principles are based on that the influence of weathering and productive explosion on the slope stability decreases with the increase in excavation depth. A study on the space principles using 3-D Finite Element Method shows that the excavation process is a process of rock stress reducing around furrow pits. In the same excavation depth, with the excavation size expanding, the scople and value of stress reducing increase, so does the difference between σ_1 and σ_3, and the slope stability gets worse. It means that a slope with a smaller curvature radius has a better stability, i. e, arching effect principle; the huge bottom of furrow pit can bear and transfer the original horizontal stresses in the lower slope, and it is favorable to the stability of the lower slope. The preliminary proving of the two principles gives part of the theory base to the adoption of convex curve slope in furrow pits to reducing stripping.