DESIGN AND CONSTRUCTION OF WATER HOLDING BULKHEADS AT XSTRATACOAL"S OAKY NO 1 MINE

A systematic approach is required for the design of bulkheads including consideration of the longevity of building materials, quality control during construction and methods to monitor performance of the retention system. Bulkhead site preparation and construction method using wet mix concrete is described with particular reference to anchoring the bulkheads to the strata with keys and steel bolts and post-construction resin injection of the concrete/strata interface. Because of coal seam contour shape it is sometimes necessary to store high heads and volumes of water in areas of the mine that are at a higher contour level than the working longwall or development panels inbye of these areas. The location and head requirements of hard barriers such as bulkheads is critical and as far is practical potential conduits, for example boreholes, joint sets, partings and shear zones should be sealed in the zone effected by the impoundment. The erosion capacity of water driven by a permanent and substantial pressure head is strong and constant with potential for scouring joints and cracks with increased site permeability. For this reason organic resin injection of bulkhead sites was chosen for blocking leakage paths at bulkhead sites and increasing strength of strata confining the bulkheads. Additional secondary support can be particularly effective in containing relaxed incumbent strata.