DESIGN METHOD FOR MINING UPPER PROTECTIVE SEAM CLOSE TO TOTAL ROCK FOR USE IN COAL-BED MINING

摘要

A design method for mining an upper protective seam close to total rock for use in coal-bed mining. On the basis of geological condition information of a protective seam mining project and physical mechanical parameters of a coal-rock mass, a numerical analysis method is used to determine an expansion deformation rate φ of the protective seam, a destruction depth K of a plastic zone at the floor of the protective seam, a coal-bed gas pressure P, a protective seam mining thickness M which satisfies provisions outlined in Provisions on Prevention and Control of Coal and Gas Outbursts, and a spacing H between the protective seam and a protected seam; and according to a percentage of the mining thickness of a rock layer in the upper protective seam close to total rock, a mining process for the protective seam close to total rock is determined from among: a traditional fully mechanized mining process, a traditional fully mechanized mining process assisted by single-row hole blasting and pre-splitting, and a traditional fully mechanized mining process assisted by double-row three-hole blasting. The present method can provide a theoretical basis for safe stoping of a low-permeability high gas coal seam when there is no conventional protective seam to be mined, which further enriches design methods for mining protective seams. The method is cost-effective, safe and efficient, and widely practicable.