Slope of an Open Cut Mine

Abstract

This invention relates to open cut mines and in particular an improved slope to of an open cut mine. The slope includes a substantially vertical batter face ( 5 ) with a plurality of reinforcing members ( 10 ) spaced from a crest ( 7 ) of the batter face ( 5 ).

1 . An improved slope of an open cut mine including a plurality batters with a berm extending from a toe of each batter, each batter having an excavated batter face which is substantially vertical and extends from the toe to a crest of the batter, reinforcing means installed prior to the excavation of the face and spaced from the proposed crest, the reinforcing means including a plurality of reinforcing members each located in a substantially vertical borehole formed at said spacing from the proposed crest, each borehole extends to a depth of at least the distance between the crest and the toe, each reinforcing member extends substantially the depth of the each borehole 
     
     
         2 . An improved slope according to  claim 1  wherein the depth of each borehole exceeds the distance between the crest and the toe by up to 15%. 
     
     
         3 . An improved slope according to  claim 1  wherein each borehole is spaced from an adjacent borehole by between 1000 mm and 5000 mm. 
     
     
         4 . An improved slope according to  claim 1  wherein each reinforcing member is a bar or cable of a diameter of between 20 mm and 100 mm. 
     
     
         5 . An improved slope according to  claim 4  wherein the bar or cable is formed from steel. 
     
     
         6 . An improved slope according to  claim 1  wherein each reinforcing member is formed from fibreglass. 
     
     
         7 . An improved slope according to  claim 1  wherein the reinforcing member is grouted in position in the borehole. 
     
     
         8 . An improved slope according to  claim 1  wherein the length of the reinforcing member exceeds the depth of the borehole. 
     
     
         9 . An improved slope according to  claim 8  wherein the reinforcing member extends out from the borehole to interact with a safety fence extending between the plurality of boreholes. 
     
     
         10 . An improved slope according to  claim 1  wherein the length of the reinforcing member is less than the length of the borehole so that the reinforcing member is countersunk in the borehole. 
     
     
         11 . An improved slope according to  claim 1  wherein the substantially vertical face is within the range of 75° to 90°. 
     
     
         12 . An improved slope according to  claim 1  wherein each borehole is spaced from the crest by no less than 800 mm. 
     
     
         13 . A method of forming a reinforced rock slope in an open cut mine including drilling a plurality of vertical boreholes to a borehole depth, locating a reinforcing member in each borehole which is substantially the length of the borehole depth, grouting the reinforcing bar in the hole, locating a crest of a batter which is spaced from the boreholes, excavating a face to the batter which is substantially parallel with the boreholes, the height of the batter face from the crest to a toe is no less than the depth of the borehole adjacent the face, wherein the excavation of the face is performed after the reinforcing member has been grouted in place in the borehole. 
     
     
         14 . A method according to  claim 13  including drilling each borehole so that it is no greater than 300 mm in diameter. 
     
     
         15 . A method according to  claim 13  including spacing the crest of the batter from each borehole so that the reinforcing member is behind the crest of the batter by no less than 800 mm. 
     
     
         16 . A method according to  claim 13  including spacing each borehole from its adjacent borehole at no less than 1000 mm centres. 
     
     
         17 . A method according to  claim 13  including providing a reinforcing member in the form of a reinforcing bar is no less than 40 mm in diameter. 
     
     
         18 . A method according to  claim 13  including drilling the borehole depth to exceed the height of the face of the batter by at least 15%. 
     
     
         19 . A method according to  claim 13  including providing a length of the reinforcing member that is less than the length of the borehole so that the reinforcing member is countersunk in the borehole. 
     
     
         20 . A method according to  claim 13  wherein the method of excavating the face includes drilling and blasting to produce the substantially vertical face within a range of 75° to 90°.