Study On The Geotechnical Properties Of Surrounding Rocks And Mining Method In Boka Gold Mine

Boka gold mine is located in the Yunnan-Guizhou Plateau, the intersection zone of Jinsha River and Xiao River. In the mining area, high mountains and steep slops and broken lithology caused great difficulties to the layout of mining engineering and production. By analyzing the basic characteristics of surrounding rock engineering in Boka gold mine, the paper determined the relatively reasonable development scheme and mining method; and undertook economic evaluation and analysis of the mine to deter mine the break-even point; and ground-penetrating radar was used for advanced geological forecast in mining well project to ensure construction safety.By using the method of sample collection, theoretical analysis and engineering monitoring, the quality characteristics of surrounding rock and the stability of roadway surrounding were studied in Boka gold mine. Considering the choice of mining methods between opencut and underground mining, the mine slope stability was studied by the methods of drilling to expose and slope geophysical exploration. It was concluded that the mine seam is located in the structurally fractured zone; the most rock mass was broken and the structural planes developed in this area. The exploration type of mining engineering geology belongs to moderately complex type mainly made up of loose-soft rocks.Based on the consideration of technical feasibility, economical rationality and other factors, the comparative research between the development schemes of mine admit with blind shaft and inclined well with blind shaft by the evaluation of mine technology and economy. The development scheme of inclined well with blind shaft was more suitable for the Boka gold mine by the systematic comparison and selection. In evaluating the quality of rock mass based on the control of underground pressure and safety mining, from a security perspective, a method of mining are studied, the final choice the upward horizontal slicing and tailing cemented filling mining method and the upward drift stop with cemented filling mining method were used in the mining stop By studying the technical and economic evaluation of Boka gold mine with the application of break-even analysis and sensitivity factor analysis, the paper determines the mining break-even point is42.75%(i.e., the annual production is56400tons when the break-even point is achieved; we can gain beyond the yield, conversely loss). Meanwhile, the sensitivity of sales price, operating costs and construction investment were analyzed; the results show that:the sales price is the most sensitive factor, followed by the operating costs and construction investment.The security risks maybe encountered during mining construction, such as old underground workings, water inflow and crushed surrounding rocks, were advanced geological forecasted by using ground penetrating radar. The results verified that the ground penetrating radar can accurately identify the distribution of geological body in front of the tunnel work face, and could forecast unfavorable geological body such as broken fault zone, aquifer, empty geological body with higher resolution, and the advanced forecast results could provide objective and direct reference data for the change of rock mass classification to effectively reduce or avoid the engineering accident.