Dual-index method for quantitatively judging gob-side entry driving time of extra-thick coal seam

Abstract

The invention relates to a dual-index method for quantitatively judging gob-side entry driving time of an extra-thick coal seam. The dual-index method comprises the following steps: (1) determining gob-side entry driving time T1 by taking main roof subsidence as an index; (2) determining reasonable driving time T2 by taking entry surrounding rock fracture development depth as a time index; (3) determining the reasonable gob-side entry driving time T. The dual-index method obtains the main roof subsidence and overburden rock movement stability time on the basis of fully considering the difference between coal and a rock mass, and is more consistent with actual conditions on site and more accurate in result. The dual-index method introduces the entry surrounding rock fracture development depth as the additional index, so that a dual-index system for the gob-side entry driving time is formed. The dual-index method takes 70% of a maximum main roof subsidence value and 80% of a maximum fracture depth as evaluation indexes of the entry driving time, and determines the weight proportion of the maximum main roof subsidence value and the maximum fracture depth according to specific geological conditions so as to comprehensively obtain the gob-side entry driving time, thereby ensuring the safety and stability of surrounding rocks of a gob-side entry, reducing the gob-side entry driving time of the extra-thick coal seam, and guaranteeing normal replacement of mining and driving.

Description

technical field [0001] The invention relates to the field of coal mine roadway excavation and support, in particular to a double-index method for quantitatively judging the excavation time of a gob-side roadway in an extra-thick coal seam. Background technique [0002] Due to the advantages of high production, high efficiency, reduced roadway excavation, and ease of tension in the working face, gob-side roadway technology has been widely used in thin coal seams and medium-thick coal seams. Thin coal seams refer to coal seams with a single layer thickness less than 1.3m , The medium-thick coal seam refers to the coal seam with a single layer thickness greater than 1.3m and less than 3.5m. In the process of mining thick and extra-thick coal seams, gob-side entry is rarely used, and the roadway protection method with 20-30m wide coal pillars is mostly used. Thick coal seams refer to those with a single layer thickness greater than 3.5m and less than 8.0m Coal seams, ultra-thic...

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Problems solved by technology

[0004] Through a large number of literature searches, it is found that there are no theoretical research and practical reports on the excavation time of gob-side roadways in ultra-thick coal seams above 15m

In the current engineering practice of extra-thick coal seams above 15m, there are two commonly used methods to determine the excavation time of gob-side roadway: one is to excavate the roadway after the movement of overburden rock is fully stabilized, that is, 12 to 16 months. The surrounding rock of the roadway is stable, and the maintenance of the roadway is good, but it seriously affects the succession of the normal production of the mine, resulting in difficulties in mine connection and a sharp drop in profitability

The second is to continue to use the traditional time of digging roadways from April to June, that is, to start digging roadways from April to June after the completion of mining at the adjacent working face. Severe deformation and instability of empty roadway

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