Mine roof control

Claim 3

The method of claim 1 wherein a plurality of parallel boreholes are utilized.

Claim 4

The method of claim 1 wherein said mineral seam is a coal seam having a substantially uniform height and includes a mined-out area.

Claim 5

The method of claim 3 wherein the vertical height of the sealed off portion of the borehole is from 30 to 70 times the height of said mined-out seam.

Claim 6

The method of claim 4 wherein the vertical height of the sealed off portion of the borehole is about 50 times the height of the mined-out seam.

Claim 7

The method of claim 4 wherein said mineral seam is a coal seam being developed by long wall mining.

Claim 8

The method of claim 6 wherein said borehole extends to a point adjacent an edge of a mined-out area.

Claim 9

The method of claim 7 wherein a plurality of parallel boreholes adjacent an edge of a mined-out area are utilized.

Claim 10

The method of claim 8 wherein said boreholes are inclined at an angle of about 18° away from the mined-out area and the fracture plane is generated by injection of water at a pressure of from 100 to 1000 kg/cm 2 .

Claim 11

The method of claim 9 wherein said boreholes are parallel to a mine entryway, and a caved-in zone larger than the natural caved-in zone resulting from mining is created.

Claim 12

In a long wall mining operation in which an entryway extends parallel to an edge of an area being mined and in which an entryway support system comprising a series of pillars extends between said edge and said entryway, the improvement wherein the caving zone of said area being mined is increased by the method comprising: (a) drilling at least one borehole to a point adjacent said edge of said area being mined, said borehole being at an angle of from 0 to 30 degrees away from a vertical plane through said edge and toward said entryway; (b) sealing off a portion of said borehole from a vertical height of from 20 to 400 meters above said point to said point; and (c) injecting fluid into the sealed off portion of said borehole at a pressure sufficient to create a fracture plane whereby the caving zone above the area being mined is increased toward said opening and the load on said opening support system is reduced.

Claim 13

In a long wall mining operation in which an entryway extends parallel to an edge of an area being mined and in which an entryway support system comprising a series of pillars extends between said edge and said entryway, the improvement wherein the caving zone of said area being mined is increased by the method comprising: (a) drilling at least one borehole to a point adjacent said edge of said area being mined, said borehole being at an angle of from 0 to 30 degrees away from a vertical plane through said edge and toward said entryway; (b) sealing off a portion of said borehole from a vertical height of from 20 to 400 meters above said point to said point; and (c) injecting fluid into the sealed off portion of said borehole at a pressure sufficient to create a fracture plane whereby the caving zone above the area being mined is increased toward said opening and the load on said opening support system is reduced.

Claim 14

The method of claim 11 wherein a plurality of parallel boreholes are utilized.

Claim 15

The method of claim 12 wherein the vertical height of the sealed off portion of the boreholes is from 30 to 70 times the height of the seam being mined out.