Non-entry method of underground excavation in weak or water bearing grounds
AssigneesCigar Lake Mining Corporation, Cogema
InventorsClovis Caleix, Jean-Luc Narcy
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Abstract
A method of excavating an underground area liable to flooding or collapsing during excavation, wherein the area is susceptible to disaggregation by high pressure water jet and is located above rock of strength suitable for drifting a gallery comprises drifting a gallery in the rock beneath the area, freezing at least a perimeter of the area to form a frozen perimeter, and excavating material from within the frozen perimeter using a high pressure water jet and one or more boreholes between the gallery and the area. Preferably the whole area is frozen for excavation.
Claims20
A method of excavating an underground area liable to flooding or collapsing during excavation, wherein said area is susceptible to disaggregation by high pressure fluid and is located above rock of strength suitable for drifting a gallery, which method comprises:
- a) drifting a gallery in the rock of strength beneath the area,
- b) drilling a plurality of freezeholes from the gallery upwardly through the rock of strength, the area and beyond the area to be excavated, said plurality of freezeholes being sufficient in number and location to support freezing at least a perimeter of the area,
- c) freezing at least the perimeter of the area to form a frozen perimeter,
- d) while sustaining said frozen perimeter, drilling a borehole upwardly to within the frozen parameter and excavating material from within the frozen perimeter using a high pressure fluid, forming a slurry of excavated material,
- e) directing said slurry downwardly into a slurry conduit and
- f) conveying the slurry away from the excavation area.
A method of excavating an underground area liable to flooding or collapsing during excavation, wherein said area is susceptible to disaggregation by high pressure water jet and is located above rock of strength suitable for drifting a gallery, which method comprises:
- a) drifting a gallery in the rock beneath the area,
- b) drilling a plurality of freezeholes from the gallery upwardly through the rock of strength, the area and beyond the area to be excavated, said plurality of freezeholes being sufficient in number and location to support freezing of the area,
- c) freezing the area,
- d) while sustaining freezing of the area, drilling a borehole upwardly to within the frozen area and remotely excavating material from within the area using a high pressure water jet, thereby forming a slurry of excavated material,
- e) remotely directing said slurry downwardly into a slurry conduit and
- f) conveying the slurry away from the excavation area.
Dependencies are inferred from the claim text.