Strengthening method for gob-side entrydriving narrow coal pillar

Abstract

A strengthening method for a gob-side entrydriving narrow coal pillar comprises the steps that firstly, an ultra-long horizontal drill hole and top and bottom plate inclined drill holes are drilled in the narrow coal pillar inside an upper section mining roadway, the length of the ultra-long horizontal drill hole is larger than the width of the narrow coal pillar. A grouting off target prevention bag and horizontal and inclined grouting anchor rods are installed inside each drill hole. A unilateral cable-stayed anchoring system, a unilateral transverse side limiting strengthening device and a unilateral gob-side entrydriving opposite-pulling anchoring system are formed on one side of the mining roadway, after a lower section roadway to be dug is dug, machinable rods are cut off in the lower section gob-side dug roadway, a butt-joint short anchor rod, a cable-stayed anchoring system and a transverse side limiting reinforcing device are correspondingly installed on the other side of the narrow coal pillar, finally, grouting is performed on the grouting anchor rods, and prestressing force is applied to nuts. Safety and stability of the narrow coal pillar gob-side entrydriving are effectively ensured, roadway deformation is effectively reduced, a coal pillar plastic area is obviously reduced, and the roadway repair cost can be lowered. The structural design is reasonable and simple, construction is convenient, the strengthening effect is obvious, and the coal recovery ratio is increased.

Description

technical field [0001] The invention relates to a method for reinforcing narrow coal pillars in gob-side excavation, which belongs to the field of coal mine support. Background technique [0002] In coal mine excavation, gob-side entry refers to the excavation roadway completely along the edge of the goaf or with only a narrow coal pillar. Specifically, the roadway is arranged in a low-stress field on the side of the coal pillar, which is convenient for roadway maintenance , to reduce the amount of deformation. In such a structure, the coal pillar can replace the artificially constructed "isolation wall", which not only saves the cost of pumping concrete for the artificial wall, but also reduces the man-hours and material costs of the concrete pipeline laying, and avoids the transportation of concrete and other materials . In gob-side excavation, the width of the coal pillar plays a decisive role in the maintenance status of the roadway. If the coal pillar is too large, on...

AI Technical Summary

Problems solved by technology

In gob-side excavation, the width of the coal pillar plays a decisive role in the maintenance status of the roadway. If the coal pillar is too large, on the one hand, the mining roadway is arranged in the pressure-increased area, which will cause high pressure on the roadway and make support difficult. , wide coal pillars will inevitably result in waste of valuable coal resources and a low recovery rate of coal resources; therefore, under the background of maximizing the recovery rate of coal pillars in sections, it is required to leave “thin-skinned” coal pillars as much as possible, namely The narrow coal pillars with a width of 2-5m are used as the support for the separation wall between the gob-side roadway and the goaf in the upper section. Since the narrow coal pillars on the goaf side have been shaped by the support force, they are easy to lose stability. However, the current method of coal pillar support mainly adopts section coal pillar coal wall bolt support, and when it is applied to the support of narrow coal pillars, coal pillars will be generated. Small elastic core area in the inner center, large plastic area, serious roadway sidewall, obvious floor drum, poor safety and stability, etc., and it is not conducive to later maintenance, and often needs to be repaired

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