Stability of ore chutes in block caving

Abstract

The geomechanical focus of the research presented in the article is mainly due to a number of problems that the iron ore mines in Gornaya Shoria face with an increase in the depth of mining. The high natural tectonic stress state of the ore province imposes certain restrictions on the technology and parameters of mineral extraction. The mining system now in use, with blasting and multi-point ore drawing under overlying rock mass using vibrating-and-hauling facilities is a structurally complex technology. It imposes severe requirements on the stability of outlets in the bottom of extraction blocks. One of the main disadvantages of block caving with ore drawing from the bottoms of the extraction blocks is the increased indentation of the block bottom with various-purpose openings. This circumstance prompts the search for new engineering solutions, including the revision of existing ones, to enhance the safety of ore production. To this effect, the mining practices undertake scientific substantiation of measures and recommendations for safe mining operations. In the article, on the basis of mathematical and physical modeling of the stress state of rock mass, the geomechanical assessment of the stability of the outlets in the bottom of the extraction block is given. It is revealed that the technology with massive block caving in rather difficult conditions of the geodynamic stress field and at the great depth of mining, with the accepted design parameters, becomes unsafe and is accompanied by both the loss of stability of rocks and the increased number of ore arching events in ore chutes. Therefore, identification of potentially hazardous places in the structural elements of the mining system, where accidents are possible, is a very popular technique in mine support design.