Grout bag type of underground support

Abstract

A grout bag assembly ( 1 ) is provided comprising an inflatable grout bag ( 2 ) (hereinafter termed a primary inflatable grout bag) having a top ( 4 ), bottom ( 6 ) and at least one side ( 8 ) and having in an expanded condition an axis extending between the top and bottom thereof. A secondary, independently inflatable, grout bag ( 14 ) expandable in the same direction as the primary inflatable bag is attached to one end of the primary inflatable grout bag. The secondary grout bag is employed, in use, subsequent to be installation of the primary grout bag to compensate for shrinkage in the height of the primary grout bag and to thereby supplement the overall axial dimension of the grout bag assembly, in use.

1 . A grout bag assembly comprising a primary inflatable grout bag having a top, bottom and at least one side and having in an expanded condition an axis extending between the top and bottom thereof,
 wherein the primary inflatable grout bag has attached thereto, at either the top or bottom thereof in the axial direction, a secondary, independently inflatable grout bag having a top and a bottom and expandable in the same direction as the primary inflatable bag to supplement the overall axial dimension of the grout bag assembly, in use,   wherein the secondary grout bag has a substantially smaller maximum distance between the top and bottom thereof in an expanded condition relative to the maximum distance between the top and bottom of the primary grout bag in an expanded condition.   
   
   
       2 . A grout bag assembly as claimed in  claim 1  in which the secondary grout bag is of the same general shape in plan view as the primary grout bag. 
   
   
       3 . A grout bag assembly as claimed in  claim 1  in which the said maximum distance in the instance of the secondary grout bag is from about 100 mm (4 inches) to about 250 mm (10 inches) whereas the maximum distance in the instance of the primary grout bag is between about 600 mm (24 inches) and about 1500 mm (59 inches). 
   
   
       4 . A grout bag assembly as claimed in  claim 1  in which the secondary grout bag is located on the top of the primary grout bag. 
   
   
       5 . A grout bag assembly as claimed in  claim 1  in which the top of the primary grout bag and the bottom of the secondary grout bag are formed by a single common wall. 
   
   
       6 . A grout bag assembly as claimed in  claim 1  in which the primary grout bag and secondary grout bag each have a unidirectional valve-controlled inlet. 
   
   
       7 . A grout bag assembly as claimed in  claim 1  in which the primary grout bag and secondary grout bag are secured within a further outer bag. 
   
   
       8 . A grout bag assembly as claimed in  claim 1  in which a reinforcing structure is provided about at least the primary grout bag and optionally also the secondary grout bag. 
   
   
       9 . A method of installing a grout bag assembly as claimed in  claim 1  comprising positioning the grout bag assembly between a hanging wall and a foot wall of a mine with the bottom of the primary grout bag on the foot wall; filling the primary grout bag by pumping into it a grout to cause it to expand; allowing the grout to set; thereafter filling the secondary bag with grout until the top thereof engages the hanging wall and a required internal pressure is reached within the secondary grout bag; and allowing the grout in the secondary bag to set. 
   
   
       10 . A method of installing a grout bag assembly as claimed in  claim 9  in which the grout bag assembly is suspended from its top preparatory to filling the primary grout bag. 
   
   
       11 . A method of installing a grout bag assembly as claimed in  claim 9  in which the primary grout bag is filled until such time as the secondary bag in the uninflated condition becomes compressed between the primary bag and hanging wall and inflation of the secondary grout bag is effected to occupy space created between the top of the primary grout bag and the hanging wall by shrinkage of the grout in the primary grout bag.