A underground support includes a first row of panels, and a second row of panels configured to be secured to the first series of panels to define an interior space for receiving construction aggregate or concrete. Each panel of the first row of panels and the second row of panels includes a body having a top edge, a bottom edge positioned opposite from the top edge, a left edge, and a right edge positioned opposite from the left edge, with the top edges of the panels of the first row of panels configured to abut the bottom edges of the panels of the second row of panels.

An apparatus for pre-loading a mechanical constant-resistance single prop includes a rhombic stretchable bracket, a screw rod, a first cylindrical sleeve ring, and a second cylindrical sleeve ring. The screw rod is connected to two opposite apex corners of the rhombic stretchable bracket. A tail end of the screw rod is fixedly connected to one apex corner of the rhombic stretchable bracket. An end head of the screw rod passes through another apex corner of the rhombic stretchable bracket. The remaining two opposite apex corners of the rhombic stretchable bracket are respectively fixedly connected to edges of the first cylindrical sleeve ring and the second cylindrical sleeve ring through connecting rods. The screw rod is threadedly connected to the apex corner of the rhombic stretchable bracket through which the screw rod passes. A method for pre-loading a mechanical constant-resistance single prop is also provided.

An apparatus for pre-loading a mechanical constant-resistance single prop includes a rhombic stretchable bracket, a screw rod, a first cylindrical sleeve ring, and a second cylindrical sleeve ring. The screw rod is connected to two opposite apex corners of the rhombic stretchable bracket. A tail end of the screw rod is fixedly connected to one apex corner of the rhombic stretchable bracket. An end head of the screw rod passes through another apex corner of the rhombic stretchable bracket. The remaining two opposite apex corners of the rhombic stretchable bracket are respectively fixedly connected to edges of the first cylindrical sleeve ring and the second cylindrical sleeve ring through connecting rods. The screw rod is threadedly connected to the apex corner of the rhombic stretchable bracket through which the screw rod passes. A method for pre-loading a mechanical constant-resistance single prop is also provided.

An apparatus for pre-loading a mechanical constant-resistance single prop includes a rhombic stretchable bracket, a screw rod, a first cylindrical sleeve ring, and a second cylindrical sleeve ring. The screw rod is connected to two opposite apex corners of the rhombic stretchable bracket. A tail end of the screw rod is fixedly connected to one apex corner of the rhombic stretchable bracket. An end head of the screw rod passes through another apex corner of the rhombic stretchable bracket. The remaining two opposite apex corners of the rhombic stretchable bracket are respectively fixedly connected to edges of the first cylindrical sleeve ring and the second cylindrical sleeve ring through connecting rods. The screw rod is threadedly connected to the apex corner of the rhombic stretchable bracket through which the screw rod passes. A method for pre-loading a mechanical constant-resistance single prop is also provided.

An apparatus for pre-loading a mechanical constant-resistance single prop includes a rhombic stretchable bracket, a screw rod, a first cylindrical sleeve ring, and a second cylindrical sleeve ring. The screw rod is connected to two opposite apex corners of the rhombic stretchable bracket. A tail end of the screw rod is fixedly connected to one apex corner of the rhombic stretchable bracket. An end head of the screw rod passes through another apex corner of the rhombic stretchable bracket. The remaining two opposite apex corners of the rhombic stretchable bracket are respectively fixedly connected to edges of the first cylindrical sleeve ring and the second cylindrical sleeve ring through connecting rods. The screw rod is threadedly connected to the apex corner of the rhombic stretchable bracket through which the screw rod passes. A method for pre-loading a mechanical constant-resistance single prop is also provided.

A yielding mine roof support is provided which is made in the form of a hollow tube made from an epoxy, phenolic, or polyester fiberglass composite.

A yielding mine roof support is provided which is made in the form of a hollow tube made from an epoxy, phenolic, or polyester fiberglass composite.