Study On Digital Assessment And Simulation Technology At Rock Mass Engineering Quality Of Block Caving

In recent years, the lack of resources has become an important factor constraining China's economic development. With economic development, there is growing demand for raw mineral materials, and lean ore mining is being put on the agenda. Block caving method, as currently the only cost-effective method compared with open-pit mining methods has been favored by international mining enginners. In this paper, according to engineering geological conditions of first mining region of Pulang copper mine, combining "the key technology research on large underground deposits in high-intensity mining" project, some key theoretical and technical issues of cavability assessment and fragmentation prediction in block caving method are studied. The main research contents and conclusions are as follows:(1) Digital evaluation index system for block caving method rock mass engineering quality is proposed. On this basis, data collection and processing system of these indexes are established, and the quantitative method of indicators is studied.(2)The rock mass compartmentation cavability estimation method based on evaluation theory of regionalized variables and three-dimensional visualization evaluation model construction technology is proposed. Three-dimensional visualization evaluation model construction method based on VTK, and octree-based block model of complex geological bodies are achieved.(3)Based on the law of the spatial distribution, using Monte Carlo technology to simulate joint system, and using three-dimensional solid cutting techniques to build a new rock mass fragmentation prediction model of block three-dimensional interception model. Based on consideration in the joint continuity and the mechanical properties of rock mass, the model simulated the spatial distribution of structure planes according to statistical principles, and predicted rock mass fragmentation using structure planes to cut model prototype and ultimately formed a block muster consisting cutting blocks. Then, according to a new method of the block shape classification, the distribution statistic rule of internal entities rock block, which are cut out by the structure planes, size and shape are studied.(4)Based on the theoretical study and demand analysis, the rock mass fragmentation prediction system is constructed and relavent software system has been developed. And by the application of this system, the form of joint spacing distribution, joint spacing distance, and the impact of mechanical properties of integrity rock and weak surface on fragmentation distribution are studied.(5) By the application of the rock mass fragmentation prediction system, the relationship between actual block volume V and the cutting area A, between three-dimensional shape indexε,κand two-dimensional shape index, between three-dimensional sieve size S3d and two-dimensional equivalent diameter S2d are studied to derive a series of formula for estimating three-dimensional geometric parameter from two-dimensional characteristic parameters.(6) The results of multi-angle, multi-directional and in-depth evaluation of Pulang first mining region show that cavability of rock can be classified into four levels fromⅡtoⅤ. In general, the rock mass cavability of the first mining area is quite satisfactory and falls into ClassⅢ, which shows that block caving method is feasible in the first mining area. The sustained caving hydraulic radius has been calculated by Laubscher's caving chart and Mathews stability graph with values of 22-26.24m.(7) The original fragment size prediction of rock mass above 3170m level of Pulang first mining region shows that, suppose we design a mine mouth and mine roadway to 5×5m2 and chunks are calculated according to the equivalent size of larger than 1.26m, the sieve cumulative percentage for blocks sized larger than 1.26m is 59.85 percent, and there will be little chance of blocking in ore drawing point, and the blocks in this region are mainly elongated, elongated-platy and platy-cubic in shape.This research is of important significance for the development of new rock mass engineering quality digital assessment and simulation technology of block caving, and will provide useful guidance and reference to caving mining design of Pulang first mining region.