Study On The Theory And Practice About Mechanized Mining Technology Of Bound Coal At Irregular Block Sections

A large number of residual marginal coal segments have been emerging during the late-mid period in the producing mines, the extraction of these sections has great significance for increasing the mine recovery rate and prolonging the mine service-life. Mechanized mining technology is always difficult to be employed in the marginal coal segments because of the irregular shape, unstable coal thickness and surrounding with mined out space. This thesis is aimed at the study of safe and efficient mechanized mining in the marginal coal segments, and comprehensive methods involve theoretical analysis, numerical simulation and field measurement were adopted to systematically research the theory and practice of the mechanized mining in the irregular marginal coal segments. Main innovation achievements are listed as follows:(1) Fuzzy Synthetic Evaluation Method was applied to establish a geological conditions evaluation model of the irregular marginal coal segments, 9 one-class indexes and 17 secondary indexes were selected, subordinate function and reasonable weighting coefficient were determinated in the evaluation method respectively. In addition, the geological conditions of the 38 marginal coal segments in Xiqu Coal Mine were evaluated, according to the evaluation, the suitable mining methods were classified, and the proportion of the fully mechanized mining, the continuous mining and the high-grade conventional mining was 71%, 16% and 13%, respectively.(2) Based on the analysis of coal resources value structure, the benefit-cost principle was adopted to build an economic recoverable evaluation model of the irregular marginal coal segments as follows: Pⁱ - Cⁱ-OC-[M CC+( f₁*ECC₁+f₂*ECC₂)]Evaluation results were assessed as the basis of whether the marginal coal segments have the exploration value or not, and combined with the comprehensive evaluation results of the geological conditions, the reasonable mining technology and system layout of the marginal coal segments were determined.(3) Surrounding rock mechanics model for the marginal coal segments mining was established, and the influence law of the main roof break line position affecting on the mining face pressure was analyzed, too. ANSYS and FLAC3D numerical simulation softwares were applied to analyze the stress and displacement field characteristics in three typical roadways in the marginal coal segments mining face: roadway with entity coal pillar, roadway excavated in the condition of one-side is entity pillar one-side is goaf, and roadway left along goaf. Consequently, the surrounding rock mechanics of the marginal coal segments mining were revealed.(4) Take the marginal coal segments mining in Xishan coal mining area as an example, the mining methods were selected according to the comprehensive evaluation value of the irregular marginal coal segments geological conditions, three typical irregular marginal coal segments mechanized mining design methods and key technologies: variational length, adjustable inclined and continuous mining were systematic studied. The engineering practice has obtained notable economic benefits, and initially formed mechanized mining technology system in the irregular marginal coal segments. The research achievements will provide some significant models and references for the safe and efficient mechanized mining in the marginal coal segments with similar conditions.This thesis contains 82 figures, 39 tables and 108 references.