Abstract: The stress environment of surrounding rock in gob-side entry retaining has been deteriorated by mining field large area hanging, longer roof hanging along gob-side under direct thick and hard roof condition. In order to solve the problem, the characteristics of strata behaviour of gob-side entry retaining with direct thick and hard roof in over 1 000 m deep coal mine have been analyzed in this paper. The structural optimization technology of overlying strata for gob-side entry retaining with hard roof condition has been proposed, which is compounded by roof caving optimization advanced the working face and pressure relief for hanging roof structure cutting along gob-side using the deep hole presplitting blasting. Simultaneously, the relationship between the length of roof hanging along gob-side and the strength acted on filling wall has been obtained, and the paper has pointed out the reasonable length of roof hanging along gob-side for long-term stability of the surrounding rock in gob-side entry retaining is under the condition of no more than 12 m. The related research results have been successfully applied in gob-side entry retaining of 14-31010 working face in Pingdingshan Twelve coal mine, and have provided reference to the implementation of gob-side entry under the same conditions.

Key words: 1 000 m deep mine, direct thick and hard roof, gob-side entry retaining, structural optimization, roof hanging