Arched roof support
ARCHED ROOF SUPPORT (EN: arch timbering, arched support; DE: Bogenausbau; FR: soutenement cintre; ES: entibacion de cuadros; RU: арочная крепь) is the framed roof support, which comprises the individual fortified arches (metallic, concrete, combined), which are installed perpendicularly to the longitudinal axis of the mine working at the certain distance one from one another. The intervals between the arches, roof, and sides of the working are overlain by the ties. The distance between the arches is usually 0.5-1.25 metres.
Arched roof supports are designed for the fixation of the horizontal and inclined mine workings with insignificant heaving of the rocks of the soil. They use at the mines of the USSR the following types of the arched roof supports: the supple one within the workings with significant displacement of the rocks; the rigid one within the workings with established rock pressure. The metallic arch of the supple arched roof support (Figure, a) is manufactured of the rolled steel with the special trough-shaped profile; it comprises the upper segment (roof bar), and of the two lateral curved struts. The struts are connected with the roof bar in the overlapping manner with the help of the two clamps with planks; each arch is connected with the neighbouring one by the three ties (spacers), which are made of the angled steel. The flexibility of the roof support under the loading is provided on the account of the insertion of the ends of the roof bar into the lateral struts of the arched roof support (Figure, b).
The bearing capacity of the roof support arch (depending on the standard size of the special rolled steel profile and on the dimensions of the working) during the period of flexibility is 137-216 kilonewtons, and after the exhaustion of flexibility (during the rigid mode) is 245-343 kilonewtons. The value of the flexibility of the three-segment arch with the bolted flexible joints is up to 0.3 metres. There are mastered the designs of the arched roof support with the bolt-less (with cam and wedge) supple joints, and with the four-segment roof support arch (the roof bar is made of the two parts, the additional supple joint is within the vault of the arch). The arched roof supports of this design have great load-bearing capacity (during the flexible mode) and flexibility (up to 0.6 metres), while the four-segment arch, besides this, has the lateral flexibility (up to 0.4 metres).The arch of the rigid arched roof support is manufactured of the I-shaped beams or rails; it comprises two curved elements, which are rigidly
connected at the top of the vault with the help of the planks and bolts. The planks, which may be flat (made of the strap iron) or curved (cast or stamped), transfer the load directly onto the shelves of the I-shaped beams, and because of this protect the bolts against the shearing.There are used abroad the arched roof supports, which are supple, articulated supple, and rigid. There dominate among the roof support arches the supple joints and connections with the usage of the braces, half-clamps with screw thread, and planks; there are produced the arched roof supports with the wedged supple joints.
The arch of the supple roof support (a) with two supple joints (b)1. top segment; 2. lateral curved strut; 3. clamp; 4. plank; 5. bolt.
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