Arrangement for erecting columnar supporting elements for underground excavations

An arrangement for erecting a columnar supporting element of a hardenable flowable material, for a roof of an underground excavation such as a mine, the arrangement comprising

• a hollow casing for filling a hardenable flowable material to be hardened therein so as to form a columnar supporting element, said casing having a longitudinal axis and including upper and lower coaxial casing portions which are tubular and telescopable in all axial directions, each of said casing portions being composed of two open-ended semi-circular sections, said upper casing portion having an annular collar;
• two pit props located diametrically opposite relative to said casing and extending between a floor and the roof of the excavation;
• means for holding said upper casing portion in contact with a roof of an underground excavation, said holding means being arranged adjacent to said casing and longitudinally variable, said holding means including two cylinder-and-piston units each provided with a mechanical spring and having a cylinder mounted on a respective one of said pit props, and a piston cooperating with said upper casing portion, said pistons of said cylinder-and-piston units being arranged to abut against said annular collar of said upper casing portion;
• a bottom plate arranged to be placed on the floor of the excavation and having a central opening, said pit props supporting on said bottom plate, and said lower casing portion extending through said central opening of said bottom plate;
• and
• means for connecting the semi-circular sections of at least said lower casing portion with one another pivotally about a longitudinal pivot axis which is parallel to said longitudinal axis of said casing, and locking the same with one another.