Rock-bolt stabilizer device for mining and tunneling applications

A stabilizer device which can be affixed in a respective borehole in mining and tunneling, said device being adapted to perform the function of a rigid profile anchor under certain stress conditions and adapted to perform the function of an expansion achor under other stress conditions, such device comprising:

• an anchor member comprising a metal rod having a first end formed with a mixing element and which can be secured near the base of said borehole by a cementitious composition and a second end remote from said first end and extending out of said borehole,
• said anchor member being made of a material having expansion properties to perform said function of an expansion anchor;
• a first rigid metal pipe section closely surrounding a portion of said rod within said borehole adjacent said first end, said first rigid metal pipe section having a surface which can be joined to the wall of said borehole by a cementitious composition and being bonded to said rod over the length of said first rigid metal pipe section;
• and
• a second rigid metal pipe section closely surrounding the rest of the length of the rod and aligned with the first section within the borehole and extending from said first rigid metal pipe section to a location close to the mouth of the borehole, said second rigid metal pipe section having a surface which can be joined to the borehole wall by a cementitious composition and being connected to said first rigid metal pipe section by a joint which yields under certain of said stress conditions.