GB2036829A - Arches for Galleries, Tunnels or the Like - Google Patents

Abstract

The invention relates to a mine arch which has a plurality of sections, each having at least three chord members (1, 2, 3) connected together by strut members (4, 5, 6) so as to define a substantially triangular cross- sectional area. At least one end of each of the sections comprises an extension member (10) which slidably engages an associated extension member (11) of an adjacent section to enable longitudinal relative movement of the sections and rigid connection of the adjacent ends of the sections. <IMAGE>

Description

SPECIFICATION Lining Frame for Galleries, Tunnels or the Like The invention relates to a lining frame for underground galleries, tunnels or the like, which is composed of elongate sections each of which has at least three chord members forming an outer and an inner chord, the chord members being connected together by strut members. Such a frame will hereinafter be referred to as "of the kind described".

Known lining frames are composed of individual solid-walled arcuate sections of steel having a generally U-shaped or trough-shaped cross-section. The ends of adjacent frame sections are frictionally connected to form loadbearing frames which are built into the galleries at intervals. Reinforcement grids, so-called mine grids, are usually inserted into the spaces between adjacent frames and finally the whole lining is spray coated with concrete.

As these known frames cover over the rock which lies behind them, a spray shadow arises in the legion of the frames during spraying of the concrete. Thus, the finished lining consists, in effect, of a row of concrete and. steel frames arranged alternately. As regards their supporting effect these are non-continuous and noninteracting, since the reinforced concrete frames lie closely against the rock behind, whereas the steel frames touch the rock only at individual points. In contrast to the concrete frames, therefore, the steel frames support the rock only intermittently. Between the two different types of frames there exists no frictional connection at all.

For lining drifts, tunnels and other underground structures arcuate lining elements in the form of trusses are known, these being formed from chord elements and connector elements welded together as a reinforcement for a concrete lining.

In the case of these known lining elements the connector elements used for the chord elements are similar open stirrup elements of appropriate polygonal shape which are placed against one another in a zigzag shape and are welded to the chord elements closing the opening in the stirrup elements.

The frames joined together from such elements are enclosed completely by the sprayed concrete and form a reinforcement for the concrete lining.

The connection between the individual elements from which a frame is put together is effected by coupling together complementary parts on the ends of the chord elements. The coupling parts are held together by springs, wedges, cams or like connector means.

This kind of connection only allows complete frames to be produced in a range of fixed sizes and also having a quite definite cross-sectional shape. Since the cross-sections of tunnels and like excavations are unfinished and irregular the way in which the frames are put together allows of no adaption to their size or respectively their diameters to conform to the cross-section of the excavation, so that the frame must always be chosen to be smaller than the smallest crosssection of the excavation. Thus the frames alone cannot without special auxiliary means, offer any support to the rock, other than of a temporary nature.

However, supporting of the rock as soon as possible after excavation has been effected is extremely important according to the latest knowledge, because the forces which act upon the final lining of say a gallery are smaller the shorter the time that has elapsed between excavation and the application of an opposing force to impede or, as far as possible even to prevent deformation of the rock by substituting elements which to a certain extent have the same action as the excavated rock. The most favourably, according to a recent proposal, directly after the excavation of the cross-section of the tunnel, the individual sections of a lining frame are inserted and are then pressed by means of hydraulic pressure against the walls of the excavation.In such a case the end portions of adjacent sections alter their relative positions in the circumferential direction of the frame, so that, if at the end of the pressure procedure the ends of adjacent segments are rigidly connected together, a prestressed frame is obtained.

The invention is concerned with the problem of creating a lining frame composed from strutted sections which allows a supporting structure to be formed in the gallery, the structure can be capable of adaption to the cross-section of the excavation and being pressed against it so as to be suitable for the temporary and direct support of the walls of the excavation until the introduction of the concrete lining, and which after sheathing with the concrete takes over the function of a concrete reinforcement running in the circumferential direction of the gallery.

According to the present invention in a frame of the kind described the strut members and chord members define substantially triangular cross-sectional areas, and devices are provided on at least one end portion of each section for guidance of the end portion of the adjacent section in the longitudinal direction of the sections and for rigid connection of the adjacent sections in the desired positions.

Preferably, the strut members are formed by zig-zag shaped elements and these are welded to the chord members.

Because of their low weight and their high elasticity under bending loadings frame sections in accordance with the invention are considerably easier to handle and for the new lining method explained above can be employed considerably better than the solid-walled mine sections customary hitherto. In contrast to the already mentioned known strutted frame segments those in accordance with the invention are suitable for the new method of lining because of greater torsional stiffness assured by the special kind of strutting and because of their possibility of coupling to neighbouring segments, variable in the peripheral or longitudinal direction, assured by the special construction of the end portions.

After the erection of the frames in accordance with the invention and after the application of the concrete lining the concrete lies close against the rock at all points and therefore supports it continuously and uniformly. Moreover even at the points at which the frame segments are connected together by the connecting pieces filling in of concrete behind the connected pieces is possible because of their short peripheral length, which allows filling in from their ends without difficulty.

In order to enable sliding guidance of the end portions of adjacent sections in the peripheral/longitudinal direction, and in order to create a possibility of rigid connection of the end portions of adjacent elements in optional relative positions by particularly simple means, the end portions next to one another on adjacent sections are advantageously made to fit together complementarily so as to be able to be slid with respect to one another in the peripheral/longitudinal direction, and can be connected together by at least one clamping device. For each point of connection two clamping devices are advantageously employed arranged at a distance apart.

In order to create the largest possible cooperating areas along which forces may be transmitted by frictional contact it is advantageous to make the end portions so that they can wedge closely into one another. In accordance with a further feature of the invention, for this purpose the end portions next to one another on adjacent segments are made as solidwalled trough-shaped moulded bodies which have an approximately U-shaped cross-section and which have the same wall thickness at every section taken in parallel with their axis of symmetry.In order to be able to transmit tangential forces in the reinforcement after embedding in the concrete has been effected, without being dependent upon the forces of friction prevailing along the walls of the end portions of the segments and the permanent efficacy of the clamping devices, members may be connected to the end portions of the sections by e.g., welding, by which forces may be introduced into the chord members of the adjacent frame section indirectly via the concrete sheathing all of the members, after the style of projecting reinforcement.

Preferably, on the one end portion of adjacent sections an extension of the outer chord is formed extending over the other section and on the other end portion an extension of the inner chord is provided, extending over the first section.

Preferably all of the strut members have a zigzag shape. By the employment of fairly long rods for the strut members, bent in a zigzag shape, the production of the frame segments is facilitated, because the timewasting delivery and exact putting together of a large number of individual parts iridependent of one another is avoided.

If ali of the strut members between the chord members are formed out of continuous wires bent in zig-zag shapes, a three-dimensional truss results, having a maximum stiffness in bending and torsion, and in which diagonal members associates with one another in pairs are connected to a chord in such a way that the buckling behaviour of the chord when loaded in compression is favourably influenced.

In order at the time of pressing the sections against the rock, to bring into effect the largest possible forces as directly as possible against the rock, i.e. without the large compressive forces necessary having to be introduced via the truss or strut diagonals, the strut members which run towards the members forming the outer chord should form tangents to the inner, facing sides of these outer chord members, so that the outer chord members are exposed and the pressure tools can be brought into action directly against these members.

In general, for lining frames in accordance with the invention, arcuate sections are employed, in particular arcuate shaped sections, which when put together yield round, in particular circular, lining frames. But arcuate and straight frame sections may also be combined together, e.g., in order to obtain frames of horseshoe shape, or else only straight sections may be employed, e.g., in order to obtain frames of trapezoidal shape. In order to achieve a corner connection, the end portions of two neighbouring sections may be connected together by an anglepiece interposed between them and which is adapted to the shape of these end portions.

By cold-forming of the chord and strut member high strength may be made possible in the case of low alloying additives. However, electrical resistance welding of the chord and strut members has the great advantage of needing a very short time for the connection of the individual elements. But, if large diameters are necessary for the chord members, then at the present state of technology uniform cold-working is no longer possible, or possible only under unacceptably high outlay. In this case it will be necessary, in order to achieve the desired strength of the chord members, to use alloying techniques in particular by increased carbon content. Even in such a case rational resistance welding is still applicable if the boom members consist of a steel having a carbon content of more than 0.3% and where necessary other alloying additives, whereas strut members consisting of steel and having a lower carbon content than the chord members are, where necessary, coldworked.

Examples of lining frames constructed in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 shows the cross-section of a frame section having chord members arranged in a triangular array; Figure 2 shows the cross-section of a frame section having chord members arranged in a trapezium shaped array; Figure 3 shows the cross-section of a frame section having a triangular cross-sectional shape, but having an altered arrangement of the strut members as compared with Figure 1; Figure 4 shows the cross-section of a frame section of similar to that Figure 3, but in which the chord members have a rectangular crosssection; Figures 5 and 6 show part of a frame section of Figure 3 in side elevation and in plan respectively;; Figures 7 and 8 show the connection of two adjacent frame sections by means of their end portions, in longitudinal section and in crosssection respectively; and, Figure 9 shows a corner connection for adjacent frame sections.

The frame section shown in Figure 1 has chord members 1, 2, 3 arranged in a triangle. The two chord members 1 and 2 have the same crosssection and form the top or outer chord of the frame section, and the ross-sectional area of the chord member 3 is preferably equal to the sum of the cross-sectional areas of the chord members 1 and 2. All of the chord members are connected in pairs by strut members 4, 5, 6 bent in a zig-zag shape. Each strut member being welded at successive points of bend alternately to one or other of the two chord members connected by this strut member.

The frame section shown in Figure 2 has in cross-section four chord members 1, 2, 7 and 8 arranged in the form of a trapezium, each chord member preferably have the same cross-sectional as the others. The chord members are connected together in pairs by strut members 4, 5, 6 and 9.

The frame section illustrated in Figure 3 has three chord members 1, 2 and 3, the arrangement of which agrees with that of the Figure 1 example, but the strut members 5, 6 are welded to the inner, facing sides of the outer chord members 1, 2. Similarly the strut member 4 is welded to the inner sides of the outer chord members 1, 2 which face towards the inner chord 3. A pressure tool can therefore easily be brought into action at the points indicated by the arrows P in order to press the frame segment into engagement with the rock directly against the outer chord without the pressure forces having to be carried via the strut members 5 and 6. Figures 5 and 6 show a side elevation and a plan respectively of a frame section in accordance with Figure 3.

The chord members do not as hitherto assumed have to have a circular shape, on the contrary members having other cross-sectional shapes may also be used, say, rectangular, square, hexagonal or oval members. Figure 4 shows a cross-section through a frame section of similar construction to Figure 3, but in which the chord members have a rectangular shape in which case as illustrated a large plane zone of contact can be achieved in a simple way between the crests of the zig-zag shaped strut members and the flat sides of the rectangular chord members. This is particularly favourable if the frame section is formed by an electrical resistance welding method.

As may be seen in particular from Figure 5 the frame section has the shape of an arc, e.g., generally the shape of sections of a circle so that a number of sections can be put together into a closed, circular frame.

The connection of adjacent frame segments is illustrated in Figures 7 and 8. To the ends of the chord members 1, 2 and 3 of a frame section there is welded an end portion 10 in the form of a solid-walled generally U-shaped body, the wall of which is so shaped that it has the same wall thickness at every section taken in parallel with its plane of symmetry S-S. Into such an end portion 10 an end portion 11 of like shape can be fitted closely, the portion 11 being likewise welded to the chord members 1', 2' and 3' of a second frame section. As may be seen in particular from Figure 7 the chord members reach into the end portions 10 and 11 only so far as is necessary for a secure welded connection of the chord members to the end portions.The central regions of the end portions 10, 11 are free of chord members and may therefore be pushed, one into the other, unimpeded.

By means of two strong transverse yokes 1 5, 1 6 which can be clamped against one another by bolts 17, 18 shown only diagrammatically, the end portions 10 and 11 are pressed against one another and thus secured together by a frictional connection. The transverse yoke 1 6 may be shaped in such a way that it partially encloses the end portions 10,11.

If necessary rods 12 and 13 may also be welded onto the end portion 1 to overlap the chord members 1 and 2 of the frame section welded into the end portion 1 0. In the same way a rod 14 may also be connected to the end portion 10, to overlap the member 3' of the frame section welded onto the end portion 11. Once embedded in concrete these rods form, after the style of projecting reinforcement a direct connection of the chord together and thus, after the setting of the concrete, relieve the load on the clamp connection between the two end portions.

In Figure 9 a corner connection for frame sections is illustrated which can be employed for frames of trapezoidal shape or of horseshoe shape, in which case straight sections of the shape and construction shown in Figure 1 have been assumed. As may be seen, in the corner region of the two frame sections to be connected, an anglepiece 1 9 is inserted between them, which is connected to two straight arms fitted to the end portions of the frame sections and comprises two straight sections welded together at an angle. The connection of the end portions of the frame sections to the arms of the anglepiece is effected against by one or more clamp devices.

Claims (17)

Claims.

1. A lining frame for underground galleries or tunnels which comprises a plurality of sections each having at least three chord members connected together by strut members to form an outer and an inner chord, characterized in that the strut members and chord members define substantially triangular cross-sections areas, and that devices are provided on at least one end portion of each section for guidance of the end portion of an adjacent section in the longitudinal direction of the sections and for rigid connection of the adjacent sections in the desired relative positions.

2. A lining frame according to claim 1, in which the end portions of adjacent sections comprise devices arranged to fit together complementarily to enable sliding of one section relative to the other in the peripheral or longitudinal direction.

3. A lining frame according to claim 2, the devices including means for clamping them together.

4. A lining frame according to claim 2 or claim 3, in which the devices each comprise a body having a substantially U-shaped cross-section and in which the wall thickness is the same at every section taken in parallel with the plane of symmetry.

5. A lining frame according to any of claims 2 to 4, in which each of the devices comprises an extension arranged to overlap the associated end portion of the other section.

6. A lining frame according to any of claims 1 to 5, in which the end portions of two adjacent sections are connected together by an anglepiece interposed between them, and corresponding to their shape of these end portions.

7. A lining frame according to claim 1, substantially as described with reference to any of the examples shown in the accompanying drawings.

8. A section for a lining frame of the kind described, the section comprising at least three chord members connected together by strut members to form an outer and an inner chord, characterized in that the the strut members and chord members define substantially triangular cross-sectioned triangular cross sectional areas, and that a device is provided on at least one end portion of the section for guidance of the end portion of an adjacent section in the longitudinal direction of the sections and for rigid connection of the adjacent sections in the desired relative positions.

9. A section according to claim 8, in which the strut members are formed by zig-zag shaped elements.

10. A section according to claim 9, in which the strut members are formed out of continuous wires bent in zig-zag shapes.

11. A section according to any of claims 8 to 10, in which the strut members which run between the inner chord and outer chord connect with the outer chord members on the sides of the members which face one another.

12. A section according to any of claims 8 to 11, in which the strut members are welded to the chord members.

13. A section according to any of claims 8 to 12, in which the chord members are cold-worked.

14. A section according to claim 13, in which the strut members are also cold-worked.

1 5. A section according to any of claims 8 to 14, in which chord members consist of steel having a carbon content of more than 0.3% and strut members consist of steel having a lower carbon content than that of the chord members.

1 6. A section according to claim 8, substantially as described with reference to any of the examples shown in the accompanying drawings.

17. A lining frame comprising a plurality of sections according to any of claims 8 to 1 6.