Method of relieving earth pressure in a working area
AssigneeMitsui Sekitan Kogyo Kabushiki Kaisha
InventorsOsamu Kimura, Hiroshi Kuroda
Life of this patent
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Abstract
The earth pressure in the underground working area is effectively alleviated by injecting high-pressure liquid into a weak ground stratum underlying the ore bed being excavated thereby to enlarge the stress envelope formed around the working face. The liquid injection hole is formed as by drill means to extend from the working face or a neighboring gateway through an intermediate layer into the weak stratum preferably at a point outside of the stress envelope initially formed.
Claims5
In the mining of underground ore deposits, a method of relieving the earth pressure in a working are which comprises injecting high-pressure liquid into a weak stratum (7) lying under the useful ore bed (2) to enlarge the stress envelope (A.sub.1) formed around the working area thereby to alleviate the earth pressure around the working face (1) and
- said high-pressure liquid being injected into said weak stratum at a point outside of the initial stress envelope (A.sub.1).
In the mining of underground ore deposits where a working face is formed between two spaced unmined ore portions on opposite sides of the face working space (1) and where two face gateways (4) are formed at the side margins of the working face (1), two initial stress envelopes (A.sub.1) being formed in the unmined ore adjacent the face gateways, the method of relieving the earth pressure in a working area which comprises injecting high-pressure liquid into a weak stratum (7) lying under the useful ore bed (2) to combine the stress envelopes (A.sub.1) formed around the face gateways thereby to alleviate the earth pressure around the working face (1).
Dependencies are inferred from the claim text.