Telescopic mine roof support

Abstract

A longitudinally yieldable support for underground roof support includes a first support section with a first elongate outer shell partially filled with a solid compressible filler material and a second support section at least partially filled with a second solid compressible filler material. The second support section is at least partially disposed within the first elongate outer shell and is telescopically extendable relative thereto. A bladder is interposed between the first and second support sections that is fillable in situ to cause extension of the second support section relative to the first support section when filled under pressure with a filler material.

What is claimed is: 
     
         1 . A longitudinally yieldable support, comprising:
 a first support section comprising a first elongate outer shell partially filled at a first end portion with a first solid compressible filler material and defining a opening at a second end of the first elongate outer shell between a second end and a top of the first solid compressible filler material; and   a second support section comprising a second elongate outer shell at least partially filled with a second solid compressible filler material positioned in the opening of the first outer shell, the second elongate outer shell having an outer diameter that is slightly smaller than a diameter of the first elongate outer shell to allow the second elongate outer shell to slide relative to the first elongate outer shell;   a port in communication with a space between the top of the first compressible filler and a bottom of the second compressible filler configured for filling the space with a third filler material under pressure to cause the second support section to rise relative to the first support section in order to span a space between a floor and a roof of an underground entry.   
     
     
         2 . The support of  claim 1 , wherein the first and second elongate outer shells are comprised of steel and wherein the first and second solid compressible filler materials are cast in the first and second elongate outer shells respectively. 
     
     
         4 . The support of claim  3 , wherein the second elongate outer shell is movable in a telescopic manner from a first position in which the second elongate outer shell is at least partially disposed within the first elongate outer shell to a second position in which a portion of the second elongate outer shell is maintained within the second elongate outer shell and a top of the second elongate outer shell is in contract with a roof of a mine entry. 
     
     
         5 . The support of  claim 1 , wherein the first and second compressible filler materials have substantially the same density. 
     
     
         6 . The support of  claim 5 , wherein the third compressible filler material is comprised of a solidified material having a second density that is greater than the densities of the first and second compressible filler materials. 
     
     
         7 . The support of  claim 1 , further comprising a fillable bladder interposed between the top of the first compressible filler material and a bottom of the second compressible filler material, the fillable bladder having an inlet accessible through the port for filling the bladder in situ. 
     
     
         8 . The support of  claim 7 , further comprising a one-way valve coupled to the inlet of the bladder to allow the filler material to enter the bladder but prevent the filler material from escaping from the bladder. 
     
     
         9 . The support of  claim 8  wherein the port is positioned proximate the top of the first compressible filler of the first support section. 
     
     
         10 . The support of  claim 5 , wherein the first and second compressible filler materials have a density of between about 40 and 50 lb/ft 3  and the third filler material has a density of between about 50 and 60 lb/ft 3 . 
     
     
         11 . The support of  claim 5 , wherein the bottom end of the first support section and the top end of the second support section will yield under load before a center portion of the support where the third filler material resides begins to yield. 
     
     
         12 . The support of  claim 1 , wherein the first and second support section are capable of supporting a load of at least 100,000 lbs. 
     
     
         13 . The support of  claim 12 , wherein the first and second support sections are capable of supporting a load of between approximately 100,000 lbs and 300,000 lbs as the first and second support section yield under load. 
     
     
         14 . The support of  claim 10 , wherein the first and second outer shells will fold upon themselves as the first and second support sections yield. 
     
     
         15 . A method of installing a longitudinally yieldable support in an underground entry, comprising:
 providing a first support section comprising a first elongate outer shell partially filled at a first end portion with a first solid compressible filler material and defining a opening at a second end of the first elongate outer shell between a second end and a top of the first solid compressible filler material;   providing a second support section comprising a second elongate outer shell at least partially filled with a second solid compressible filler material positioned in the opening of the first outer shell, the second elongate outer shell having an outer diameter that is slightly smaller than a diameter of the first elongate outer shell to allow the second elongate outer shell to slide relative to the first elongate outer shell; and   pumping a third filler material through a port in communication with a space between the top of the first compressible filler and a bottom of the second compressible filler configured for filling the space with a third filler material under pressure to cause the second support section to rise relative to the first support section until the support abuts against a roof of an underground entry.   
     
     
         16 . The method of  claim 1 , further comprising providing the first and second elongate outer shells of steel and separately casting the first and second solid compressible filler materials into the first and second elongate outer shells respectively. 
     
     
         17 . The method of  claim 16 , further comprising moving the second elongate outer shell in a telescopic manner from a first position in which the second elongate outer shell is at least partially disposed within the first elongate outer shell to a second position in which a portion of the second elongate outer shell is maintained within the second elongate outer shell and a top of the second elongate outer shell is in contract with a roof of a mine entry. 
     
     
         18 . The method of  claim 15 , further comprising providing the first and second compressible filler materials with substantially the same density. 
     
     
         19 . The method of  claim 18 , further comprising providing the third compressible filler material as a solidified material having a second density that is greater than the densities of the first and second compressible filler materials. 
     
     
         20 . The method of  claim 15 , further comprising providing a fillable bladder interposed between the top of the first compressible filler material and a bottom of the second compressible filler material, the fillable bladder having an inlet accessible through the port for filling the bladder in situ. 
     
     
         21 . The method of  claim 20 , further comprising providing a one-way valve coupled to the inlet of the bladder to allow the filler material to enter the bladder but prevent the filler material from escaping from the bladder. 
     
     
         22 . The method of  claim 21 , further comprising providing the port in a position proximate the top of the first compressible filler of the first support section. 
     
     
         23 . The method of  claim 18 , further comprising providing the first and second compressible filler materials with a density of between about 40 and 50 lb/ft 3  and the third filler material with a density of between about 50 and 60 lb/ft 3 . 
     
     
         24 . The method of  claim 18 , further comprising configuring the support so that the bottom end of the first support section and the top end of the second support section will yield under load before a center portion of the support where the third filler material resides begins to yield.