Mine roof anchor having adjustable resin retaining washer

A roof anchor for supporting an underground mine roof or the like comprising:

• an elongated shaft having first and second end portions operable to be positioned in a bore hole in a mine roof having an open end portion at said mine roof and a blind closed end portion in the strata above said mine roof;
• said shaft first end portion being arranged to be inserted and secured within said bore hole formed in said roof by a combination of a preselected volume of resin bonding material inserted in said bore hole in capsule form above said shaft front end portion, and
• a mechanical expansion shell assembly including an expansion shell surrounding a tapered plug threaded onto said shaft first end portion whereby said expansion shell is expanded to contact the inner wall of said blind bore hole;
• said resin bonding material arranged to bond said shaft end portion and said expansion shell assembly to the inner wall of said bore hole;
• said preselected volume of resin bonding material being initially contained in an unmixed condition within a destructible capsule positioned within said bore hole, said capsule containing an adhesive resin material in a first compartment and a catalyst hardener material in a second compartment so that when said shaft and said mechanical expansion shell assembly is inserted into said bore hole, said capsule is fractured and at least a portion of the contents of said first and second compartments are mixed together by rotation of said shaft and said mechanical expansion shell assembly whereby said resin bonding material is conditioned to secure elements of said roof anchor to the inner wall of said bore hole;
• said shaft second end portion having a bolt head formed on the extreme end thereof, said bolt head arranged to contact a roof support plate that bears against said mine roof at said open end portion of said bore hole whereby said bolt head will force said support plate against said roof when said anchor is installed in said bore hole;
• annular stop means engaged to said elongated shaft at a preselected location along said shaft between said mechanical expansion shell and said bolt head for preventing said resin bonding material from flowing from said shaft first end portion to a location downwardly in said bolt hole beyond said stop means before said resin bonding material has set;
• adjustable means positioned on said shaft for axially fixing said annular stop means at a preselected location to exert a compressive force on said resin positioned thereabove in said bore hole before said resin bonding material has been mixed by said shaft and said mechanical expansion shell and to withstand the hydraulic pressure created when said shaft and expansion shell fractures said destructible capsule;
• said adjustable means being movable to a preselected position on said elongated shaft below said mechanical expansion shell so that the location of said annular stop means on said elongated shaft is fixed before said anchor is inserted into said bore hole so that the preselected amount of said resin bonding material utilized to secure said roof anchor to said bore hole will completely fill the space within said bore hole that is not filled by said roof anchor and mechanical expansion shell assembly from the blind end of said bore hole to said stop means and cause a compressive force to be exerted on said resin bonding material within said bore hole to compress said resin bonding material before said resin bonding material hardens and sets and further compress at least a portion of said resin as said expansion shell expands and maintains said compressive force on said resin bonding material until said resin bonding material has hardened and set.

A method of supporting an underground mine roof or the like comprising:

• forming a blind bore hole upwardly in a mine roof, said blind bore hole having a wall and a closed blind end portion in the strata above the mine roof;
• inserting into said blind bore hole a preselected volume of a resin bonding material contained in a substantially unmixed condition within a destructible resin capsule with components of said resin bonding material being confined within separate compartments of said capsule;
• providing a roof anchor which includes a shaft with first and second end portions, an annular stop means on said shaft intermediate said first and second end portions and a bolt head on said second end portion;
• adjusting the position of said annular stop means along the length of said roof anchor shaft to a preselected location on said shaft between said first and second end portions to provide a volume of space between said stop means on said shaft and said closed blind end portion of said bore hole that is not occupied by said roof anchor and is less than the volume of said resin bonding material in said capsule;
• inserting said roof anchor first end portion in said blind bore hole and moving said first end portion upwardly in said blind bore hole toward said closed blind end portion,
• fracturing said resin capsule and said separate compartments therein with said roof anchor shaft first end portion while urging said roof anchor upwardly in said bore hole to trap said resin in a substantially unmixed condition between said bore hole blind end portion and said annular stop means to put pressure on said resin before said resin hardens;
• rotating said roof anchor to mix said components of said resin bonding material within said bore hole while compressing said resin between said bore hole blind end portion and said annular stop means;
• and
• maintaining said resin compressed while said resin hardens and sets.

A roof anchor for supporting an underground mine roof or the like comprising:

• an elongated shaft having first and second end portions, said shaft operable to be positioned in a bore hole in a mine roof, said bore hole having an open end portion at said mine roof and a blind closed end portion in the strata above said mine roof;
• said shaft first end portion having an expansion shell assembly including an expansion shell positioned thereon and engaging a tapered plug threaded onto said shaft first end portion;
• said shaft first end portion with said expansion shell assembly positioned thereon arranged to be inserted into said bore hole formed in said roof;
• a preselected volume of a resin bonding material positioned in said bore hole in capsule form above said shaft front end portion, said resin bonding material arranged to bond said shaft first end portion to the inner wall of said bore hole;
• said shaft second end portion having means cooperating therewith operable to bear against said mine roof at said open end portion and an enlarged head portion arranged to rotate said shaft in said bore hole;
• annular stop means positioned on said elongated shaft for exerting a compressive force on said preselected volume of said resin bonding material positioned thereabove in said bore hole, said annular stop means movable to a preselected position along the length of said elongated shaft,
• positioning means engaged to said elongated shaft below said annular stop means for locating said annular stop means at a preselected location along the length of said shaft so that upon insertion of said shaft first end portion in said bore hole said annular stop means is axially fixed on said shaft to exert pressure on said resin bonding material before said resin bonding material has set and maintains said compressive force on said resin bonding material,
• said expansion shell assembly, upon rotation of said shaft in said bore hole, arranged to exert a further compressive force on at least a portion of said resin bonding material before said resin bonding material has set and expand said expansion shell to engage the inner wall of said bore hole and provide a tension on said roof anchor shaft;
• and
• said compressive force and said further compressive force maintained on said resin bonding material until said resin bonding material has set.

A roof anchor for supporitng an underground mine roof or the like comprising:

• an elongated shaft having first and second end portions operable to be positioned in a bore hole in a mine roof having an open end portion at said mine roof and a blind closed end portion in the strata above said mine roof;
• said shaft first end portion being arranged to be inserted and secured within said bore hole formed in said roof by a combination of a preselected volume of resin bonding material inserted in said bore hole in capsule form above said shaft front end, and
• a mechanical expansion shell assembly including an expansin shell surrounding a tapered plug threaded onto said shaft first end portion whereby said expansion shell is expanded to contact the inner wall of said blind bore hole;
• said resin bonding material arranged to bond said shaft end portion and said expansion shell assembly to the inner wall of said bore hole;
• said preselected volume of resin bonding material being initially contained in an unmixed condition within a destructible capsule positioned within said bore hole, said capsule containing an adhesive resin material in a first compartment and a catalyst hardener material in a second compartment so that when said roof anchor is inserted into said bore hole, said capsule is fractured and the contents of said first and second compartments are mixed together by rotation of said roof anchor whereby said resin bonding material is conditioned to secure elements of said roof anchor to the inner wall of said bore hole;
• said shaft second end portion having a bolt head formed on the extreme end thereof, said bolt head constructed and arranged to contact a roof support plate that bears against said mine roof around the mouth of said bore hole whereby said bolt head will force said support plate against said roof when said anchor is installed in said bore hole;
• annular stop means engaged to said elongated shaft at a preselected location along said shaft between said mechanical expansion shell and said bolt head for preventing said resin bonding material from flowing from said shaft first end portion to a location downwardly in said bolt hole beyond said stop means before said resin bonding material has set;
• adjustable means positioned on said shaft for axially fixing said annular stop means at a preselected location to exert a compressive force on said resin positioned thereabove in said bore hole and to withstand the hydraulic pressure created when said roof anchor fractures said destructible capsule;
• said stop means being secured in a position on said shaft before said anchor is inserted into said bore hole so that the preselected amount of said resin bonding material utilized to secure said roof anchor to said bore hole completely fills the space within said bore hole that is not filled by said roof anchor from the blind end of said bore hole to said stop means and cause a compressive force to be exerted on said resin bonding material within said bore hole to compress said resin bonding material before said resin bonding material hardens and sets;
• and
• said expansion shell assembly arranged upon rotation of said shaft to expand said expansion shell into contact with the inner wall of said blind bore hole and further compress said resin bonding material before said resin bonding hardens and sets.

A method of supporting an underground mine roof or the like comprising:

• forming a blind bore hole upwardly in a mine roof, said blind bore hole having a wall and a closed blind end portion in the strata above the mine roof;
• inserting into said blind bore hole a preselected volume of a resin bonding material contained in an unmixed condition within a destructible resin capsule with components of said resin bonding material being confined within separate compartments of said capsule;
• providing a roof anchor which includes a shaft with first and second end portions, an annular stop means on said shaft intermediate said first and second end portions, a bolt head on said second end portion, and a mechanical expansion shell assembly having an expansion shell surrounding a tapered plug threaded onto said shaft first end portion;
• securing said annular stop means on said roof anchor shaft at a preselected location on said shaft between said first and second end portions to provide a volume of space between said stop means on said shaft and said closed blind end portion of said bore hole that is not occupied by said roof anchor and expansion shell assembly and is less than the volume of said resin bonding material in said capsule;
• inserting said roof anchor first end portion in said blind bore hole and moving said first end portion upwardly in said blind bore hole toward said closed blind end portion,
• fracturing said resin capsule and said separate compartments therein with said roof anchor shaft first end portion while urging said roof anchor upwardly in said bore hole to trap said resin by said annular stop means to put pressure on said resin before said resin hardens;
• rotating said roof anchor to mix said components of said resin bonding material within said bore hole while compressing said resin and expanding said expansion shell into contact with the inner wall of said blind bore hole to further compress said resin;
• and
• permitting said resin to set while being compressed by said annular stop means and said expansion shell assembly with said bolt head formed on the second end portion of said roof anchor shaft supporting a roof support plate surrounding said bore hole and abutting said mine roof.