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.

Abstract: A longitudinally yieldable support for underground roof support includes a first support section with a first elongate outer shell filed with a solid compressible filler material and a second support section filled with a second solid compressible filler material with a second elongate outer shell extending above the first elongate outer shell. The second support section has density that is greater than a density of the first solid compressible filler material. A pair of attachment members are coupled to the second elongate outer shell and are configured for lifting the second elongate outer shell relative to the first elongate outer shell and for securing the second elongate outer shell relative to the first elongate outer shell once lifted.

Abstract: A longitudinally yieldable support for underground roof support includes a first support section with a first elongate outer shell filed with a solid compressible filler material and a second support section filled with a second solid compressible filler material with a second elongate outer shell extending above the first elongate outer shell The second support section has density that is greater than a density of the first solid compressible filler material. A pair of attachment members are coupled to the second elongate outer shell and are configured for lifting the second elongate outer shell relative to the first elongate outer shell and for securing the second elongate outer shell relative to the first elongate outer shell once lifted.

Abstract: A longitudinally yieldable support for underground roof support includes a first support section with a first elongate outer shell filled with a solid compressible filler material and a second support section filled with a second solid compressible filler material with a second elongate outer shell extending above the first elongate outer shell. The second support section has density that is greater than a density of the first solid compressible filler material. A pair of attachment members are coupled to the second elongate outer shell and are configured for lifting the second elongate outer shell relative to the first elongate outer shell and for securing the second elongate outer shell relative to the first elongate outer shell once lifted.

Abstract: A longitudinally yieldable support for underground roof support includes a first support section with a first elongate outer shell filled with a solid compressible filler material and a second support section filled with a second solid compressible filler material with a second elongate outer shell extending above the first elongate outer shell. The second support section has density that is greater than a density of the first solid compressible filler material. A pair of attachment members are coupled to the second elongate outer shell and are configured for lifting the second elongate outer shell relative to the first elongate outer shell and for securing the second elongate outer shell relative to the first elongate outer shell once lifted.

Abstract: A longitudinally yieldable support for underground roof support includes a first support section with a first elongate outer shell filled with a solid compressible filler material and a second support section filled with a second solid compressible filler material with a second elongate outer shell extending above the first elongate outer shell. The second support section has density that is greater than a density of the first solid compressible filler material. A pair of attachment members are coupled to the second elongate outer shell and are configured for lifting the second elongate outer shell relative to the first elongate outer shell and for securing the second elongate outer shell relative to the first elongate outer shell once lifted.

Abstract: A mine prop is comprised of an elongate tube having a slenderness ratio that would generally allow buckling or kneeling of the elongate tube when exposed to a sufficient axial force. A plurality of elongate support members having a length less than the elongate tube are attached to the tube to prevent buckling or kneeling of the elongate tube along the portion of the tube to which the elongate support members are attached. The portions of the tube that are unsupported by the elongate support members define one or more yieldable zones proximate at least one end of the tube. A compressible filler material is disposed within at least portion of the tube to support yielding in the yieldable zone.

Abstract: A mine prop is comprised of an elongate tube having a slenderness ratio that would generally allow buckling or kneeling of the elongate tube when exposed to a sufficient axial force. A plurality of elongate support members having a length less than the elongate tube are attached to the tube to prevent buckling or kneeling of the elongate tube along the portion of the tube to which the elongate support members are attached. The portions of the tube that are unsupported by the elongate support members define one or more yieldable zones proximate at least one end of the tube. A compressible filler material is disposed within at least portion of the tube to support yielding in the yieldable zone.

Abstract: A foldable linear explosive charge (FLEC) comprising a plurality of similar tubular members which are hinged to each other at their ends so that they can be extended co-linearly to form a long tubular member or can be hinged and relatively rotated 180.degree. from each other to form a zig-zag folded system suitable for transport or storage. While in extended form, with the tubular members co-linear, they are wound with a helix of linear explosive compound (LEC). At the joints between each pair of tubular members, the LEC passes directly over the hinge, so when that joint is rotated from closed (folded) to open (linear) position, the explosive member is not moved, except for a rotation, in which it returns from a slight torsion. The FLEC is carried in a container in the folded condition and when it is to be inserted into a drilled shot hole, each successive pair of sticks is unfolded into a co-linear position and lowered into the shot hole.