Temporary lining

(Figure # 1) The cantilevered pullout temporary linings

TEMPORARY LINING (EN: temporary lining, temporary support; DE: vorlaufiger Ausbau; FR: boisage provisoire, soutenement provisoire; ES: entibacion provisional; RU: временная крепь) is the mining lining within the capital and preparatory underground mine workings, which is installed within their stope part during the period of the penetration.

Within the USSR, within the horizontal and inclined mine workings, there are used the upper linings: of the cantilevered pullout type, of the hanging type (in the absence of the lateral pressure and of the heaving of the rocks of the soil within the mine working); of the frame type (in case of the existence of the lateral pressure). The cantilevered pullout temporary lining (see the Figure # 1, a, b, v) comprises the metallic beams, which are situated near the roof of the mine working in the cantilevered manner, and the protective ceiling, which rests on these beams, in the form of the covering, which is made of the wooden sawn timbers, or of the upper metallic elements with the ties (in most cases, they are used later as the elements of the permanent lining).

The cantilevered beams are freely suspended on the brackets to the upper metallic elements of the permanent lining; the structure of the brackets permits to move easily the beams with the ceiling behind the stope of the mine working. In case of the continuous permanent lining, which is made of the concrete or reinforced concrete, the cantilevered beams of the temporary lining are suspended within the brackets to the anchors, which are fixated within the rocks of the roof. The hanging (of the pin type, or of the anchor type) temporary lining (see the Figure # 2, a, b) is the ceiling (fencing) in the form of the upper metallic elements with the ties or wire mesh, which (ceiling) is retained under the roof of the mine working using the anchors or metallic pins, which are embedded into the rock.

The ceiling of the hanging temporary lining is often used as the element of the permanent lining. The hanging (of the anchor type) temporary lining may also be used as the formwork for the fixation of the mine working using the monolithic lining, which is made of the concrete or reinforced concrete. The temporary lining of the frame type is used in the two versions: in the form of the portable (reusable) lining, and in the form of the stationary lining. The portable temporary linings of the frame type are the metallic arches, the trapezoidal or rectangular frames with the connection assemblies, which may be rapidly disassembled. The structure of these linings in general is analogous to the mass-produced metallic linings, which are used for the permanent lining of the mine workings. They also use as the element of the portable temporary lining of the frame type the hydraulic struts for the clearing stopes (of the 2GSK, 2GVS, and other types), and the near-stope struts of the fricti on type (of the M type). There are used the metallic inventorial linings (of the MIK type) with the flexible assemblies without the bolts (of the cam type, and of the wedge-shaped type); they are used subsequently as the permanent linings. The dismantling of the frames of the portable temporary lining (for the repeated usage) is performed after the installation of the frames of the permanent lining between them. The stationary temporary linings of the frame type are the mass-produced metallic frames for the lining, which are installed immediately near the stope of the mine working, which is being conducted, and are used later as the structural part of the permanent lining. In case of the installation of the permanent lining, which is made of the concrete or reinforced concrete, into the mine workings, the stationary metallic temporary lining remains within the concrete massif in the form of the rigid reinforcement. Sometimes, there perform the functions of the temporary lining the f rames of the permanent lining, which have been installed with the somewhat larger interval; in this case, the construction of the permanent lining is limited to the installation of the additional frames into the intervals between the frames of the temporary lining.

(Figure # 2) The temporary lining
Figure # 2. The hanging temporary lining on the pins (a) and on the anchors (b):
1 - the upper metallic element of the lining;
2 - the embedded metallic pin or anchor;
3 - the covering of the sawn timbers.

The temporary lining within the vertical mine workings (within the exploratory pits, and within the vertical mine shafts) is used for the penetration within the weak, unstable rocks. The temporary lining comprises the metallic rings (see the Figure # 3), which they hang one onto another during the advancement of the stope; the first ring is fixated to the elements of the permanent lining with the help of the hooks (hangers), which are made of the round steel with the diameter of 25-32 millimetres; the distance between the hangers along the perimeter of the ring is 1.5-2 metres. They assemble the metallic rings using the individual segments (the channel bars # 16-20).

The distance between the rings of the temporary lining is usually 1-1.5 metres. For the rigidity, they install between the rings the vertical spacers, namely, the wooden struts with the diameter of 100-150 millimetres, or the metallic pipes with the diameter of 100 millimetres. They cover the space between the rings and the walls of the mine working using the sawn timbers or wooden boards. They wedge the rings of the temporary lining during the installation.

The technical characteristic of the temporary lining (the bearing capacity, the structural parameters, the expenditure of the materials, and so on) is determined for each mine working, depending on the specific mining-geological and productive-technical conditions of the usage.

(Figure # 4) The hanging brackets of the cantilevered lining
Figure # 4. The general view of the hanging brackets for the temporary pullout cantilevered lining, which is used abroad:
a - with the curly clamps, which are fixated using the bolts with the capsular nuts;
b - with the clamping wedge, and with the roller for the movement of the cantilevered beam of the lining;
v - is made of the shaped steel, and is formed integrally with the clamp and fixating wedge;
1 - the bracket; 2 - the clamp; 3 - the capsular nut; 4 - the wedge; 5 - the roller.

Abroad, for the lining of the near-stope part of the mine workings, they use the pullout cantilevered temporary linings with the protective ceilings. They usually produce the cantilevered beams using the rails or I-beams with the length of up to 6 metres, and they attach them to the frames of the permanent lining with the help of the brackets (see the Figure # 4).

At the underground mines within Poland, there is used the portable temporary lining of the frame type, which is produced of the rolled steel with the grooved profile. The struts of the frame are extendable; each strut comprises the two segments, which are connected with the help of the wedging frictional lock. There are welded to the upper end of the strut the shoes for the laying of the upper metallic elements of the lining. The roof of the mine working is covered with the metallic mesh. The initial wedging of the frame during its installation is created using the portable jack. The lining has the constructive flexibility.

(Figure # 3) The temporary lining for the penetration of the vertical underground mine shafts

The perfecting of the upper lining, and the widening of the field for its usage, are conducted along the following directions: the creation of the mechanized movable linings, both independent, and technologically and structurally associated with the mining-penetration equipment, and which are the major part within the mechanized mining-penetration complexes (for example, the KGK-1M, KN-5N, "Progress" "Soyuz-19"); the usage of the anchors, both independently, and in combination with the other types of the linings; the mastering of the effective methods and means for the strengthening of the rocks, which are containing the mine workings.