JPS6217300A - Timbering for reticulate member connection type tunnel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is based on NATM (New Au5trian
The present invention relates to tunnel shoring that is applied to mountain construction methods such as the Tunneling Method, and particularly to tunnel shoring that is lightweight, inexpensive, and has excellent assembly workability and workability.

[Conventional technology] The NATM method is a type of tunnel construction method that prevents the collapse of earth and sand by reinforcing the strength of the ground in the excavated tunnel with sprayed concrete, rock bolts, and steel shoring. This method is widely used as a rational reinforcement method because it allows construction to be carried out while actually measuring the state of deformation of the surface.

By the way, the steel shoring used in the NATM construction method is H-shaped steel (for example, 125 x 125 x 6 x 9 m steel, or 15
The most common type of steel shoring is curved steel (0x150x7x10 etc.), and about 90% of steel shoring is made of H-beam steel (hereinafter referred to as H-shaped steel).
It is said to be a form steel shoring. In use, the H-shaped steel shoring is pre-curved into an arc shape or an arch shape according to the shape of the inner wall of the tunnel to form two rung parts at both ends, and these are assembled together along the inner wall of the tunnel to create a tunnel. The supports are installed at intervals of 0.8 to 1.5 m in the length direction, and the longitudinally adjacent supports are connected to each other by connecting members, and the supports are installed at intermediate positions between adjacent supports or each support is installed. After burying rock bolts at the points and attaching mesh members along the exposed internal wall of the ground between each shoring, concrete mixed with quick-setting agent is sprayed to form an inner reinforced wall. The most common net-like member is one made of steel wire rods, and after the sprayed concrete hardens, this net-like member functions as concrete reinforcing reinforcing bars to build a strong tunnel inner peripheral wall. become.

However, conventional H-shaped steel shoring has many drawbacks as shown below, and there is a need for improvement in terms of overall performance, including transportability and workability.

(1) The diameter of the tunnel excavation hole was excavated considerably larger than the designed value, but under these circumstances it was difficult to install highly rigid H-shaped steel supports that were in close contact with the ground. , it is easy for a void to form between the ground and the shoring. If such a void is created, stress will be concentrated on the shoring and the load-bearing capacity will not only decrease, but the excavated surface of the ground will gradually loosen, and this will become the back cylinder. Shoring and spraying may cause the load on the concrete to exceed the design value.

(2) The final strength of the tunnel is mainly provided by rock bolts and shotcrete concrete, and shoring is mainly used to prevent the ground from collapsing during tunnel construction. The subsequent contribution to the shoring action is not so large, so using high-strength H-shaped steel for such shoring would rather lead to over-design, which would be uneconomical and wasteful.

(3) In addition, it is known that the locations where particularly large stresses occur in shoring are generally the top and legs of the tunnel, so by focusing on strengthening these parts, the overall strength of the shoring can be improved. Although this can sufficiently improve performance, it is difficult to partially change the cross-sectional dimension in the circumferential direction with H-beam steel shoring, and as it is determined based on the maximum stress, it may result in over-design as described above. This promotes waste.

(4) The flanges and webs of H-type steel shoring are formed of surface elements, and when spraying concrete with a spray machine, some of the concrete tends to bounce off the flat plate parts (flange parts and web parts). , Spraying involves a lot of material loss.

(5) In addition, the flange surface of H-shaped steel becomes a steric obstacle,
When spraying onto the back surface, it is necessary to spray with the sprayer oriented diagonally in order to prevent concrete filling failure, and in this case, there is a particularly large amount of material rebound loss during spraying.

(8) The sprayed concrete used in the NATM construction method is a cylindrical pressure-resistant structure that is integrated with the ground and H-shaped steel shoring to resist the load of the ground, but the concrete that is sprayed with the H-shaped steel shoring is When used, as shown in Fig. 7 (partial sectional view), the concrete 2 cannot be sufficiently filled when spraying on the back side of the H-shaped steel support l or the part sandwiched between the flange and the web, leaving a void S. The continuity in the axial direction is lost, resulting in a structural defect (3 in the figure indicates the ground).

(7) When constructing a tunnel using the NATM construction method, the rock bolts 4 are not only driven perpendicularly to the ground 3 as shown in Figure 8 (partial cross-sectional view), but also toward the front of the excavated hole. In some cases, the ground in the area to be excavated after driving the rock bolt 4 is preliminarily reinforced (generally, the first hit is called a rock bolt).In this case, the first hit that is driven forward is the first place where the rock bolt 4 is driven. It is said that it is more effective to keep the direction as close to horizontal as possible along the longitudinal direction of the excavated hole (the state shown by the broken line in Figure 8). However, when using H-shaped steel supports, the web surface of the support This is a hindrance, making it impossible to bring the driving direction close to horizontal, making it impossible to achieve the purpose of strengthening the ground sufficiently effectively.

(8) H-shaped steel supports are extremely heavy; for example, one for a two-lane expressway tunnel weighs 500 to 700 kg.
It is difficult to handle in narrow tunnels because it reaches
Moreover, the burden on human resources and equipment becomes greater.゛(9) When constructing a tunnel, after placing H-shaped steel supports at appropriate intervals as described above, attach mesh members to the exposed ground surface and secure them with lock pins, etc., and attach H-shaped steel supports to both ends. It must be connected to the shoring using wires or the like, and the work required to attach the net-like member and connect it to the shoring is complicated and takes a long time, which further increases the burden on the workers.

[Problems to be Solved by the Invention] The present invention has been developed to address these circumstances and to develop an RF L, which is not only lightweight and has good workability and handling, but also has no excess or deficiency in strength. As a result of repeated research into various types of shoring, we developed a so-called bar shoring system in which at least two wooden rods are arranged approximately parallel to each other and assembled together using connecting members, and we have previously filed a patent application. Ta. This bar support T has two or more (four in the figure) bars 5 approximately parallel to each other, as shown in FIG. 9 (cutaway perspective view of essential parts) and FIG. They are arranged in a row and assembled integrally using a connecting member 6, and since the entire structure is made of bar elements, it is lightweight and has good workability and handling.

There are no problems like the ones pointed out with H-type steel shoring, such as the problem of strength defects due to unfilled areas remaining with spraying, or the problem of loss of concrete with spraying, and the size and number of bars can be reduced. There are various advantages such as the ability to freely adjust the strength by changing the strength, so there will be no excess or deficiency in the strength.
) The problems mentioned above have been resolved to some extent. 11th~
Fig. 18 shows various modifications of the bar support according to the invention of the earlier application, Figs. 11 to 16 are cutaway perspective views of essential parts, and Fig. 17.
Figure 18 is a cross-sectional view.

However, the problem (9) above is still unresolved, and the work required to attach the mesh members and connect the mesh members to the shoring is extremely complicated, and is a major cause of reducing the efficiency of tunnel construction. Under these circumstances, the present invention aims to provide a tunnel support that can also solve the problem (8) above.

[Means for Solving the Problems] The configuration of the net-like member connecting type tunnel shoring according to the present invention is such that two or more rods are arranged substantially parallel and assembled together by at least one connecting member. The gist is that a tunnel support is formed and a net-like member is integrally joined to the support.

[Function] In order to solve the above-mentioned problems related to H-type steel shoring, the present invention adopts the technology of the above-mentioned patent application as the basic structure, and also integrally assembles the net-like member to the basic structure. did. That is, first, the shoring body is constructed from bar elements, and at least two of the bar elements are arranged substantially parallel and assembled using at least one connecting member to form a basic structure. With this basic structure, it is possible to adjust the number of bar combinations, the diameter of the bars, and the pitch of the connecting members.
In the case of shoring installed in areas where large loads or stress are applied, it is possible to improve H-shaped steel shoring by increasing the number and diameter of the bars in that area, or by shortening the pitch of connecting members. Not only can it eliminate the economic and strength waste that occurs when using shoring, but it can also significantly reduce the weight of the shoring, dramatically improving its transportability, handling, and construction workability. . Moreover, since the bar elements do not have planar parts, there is no risk of spraying causing problems such as splashing of the concrete or poor filling as explained in FIG.

However, not only is the reinforcing effect of just one wooden bar insufficient, but spraying also fails to sufficiently improve the integrity with the concrete, and the original function of the shoring is not demonstrated. Therefore, in the present invention, by arranging two or more rods substantially parallel and assembling them with at least one connecting member to integrate them, the minimum strength for shoring is ensured, and furthermore, if necessary, This can be divided into appropriate lengths and flanged connecting members attached to both ends to form a relatively small-volume shoring, which can then be assembled along the inner circumferential wall of the tunnel to form a bar shoring body. I'm doing it like that. In this specification, the shoring body means not only the unit or piece-like parts before being assembled as a whole, but also the entire appearance after being assembled.

In the present invention, a net-like member attached along the ground surface is integrally joined to the above-mentioned bar shoring main body in advance to constitute a tunnel shoring as a whole. Construction is carried out by integrating the bar shoring body and the net member. Therefore, not only the construction work is greatly simplified, but also the spraying allows the concrete, the rod support body, and the mesh member to be integrated into a strong inner peripheral wall of the tunnel after the concrete has hardened.

In addition, iron or steel is the most common material for the bars and net-like members constituting the bar shoring body in the present invention, but it is not limited to this, of course, and other metal materials or hard materials may be used. The use of synthetic resins, FRP, carbon reinforced materials, ceramics, etc. is not excluded.

[Example] Figures 1 to 3 illustrate the most typical tunnel support (hereinafter referred to as net-like member integrated type support) according to the present invention, and Figure 1 shows the construction state on the ground. Front view, Figure 2 is a view of Figure 1 seen from the bottom side, Figure 3 is the ■ in Figure 1.
As is clear from these figures showing the -m line cross section, the net-like member integrated shoring of this example has four rods 5 arranged substantially parallel to each other so as to have a rectangular cross section, and an H-shaped cross section. Connecting member 6-4
It is constructed by integrally joining the shoring body I, which is welded and assembled near the apex, and the net-like member ■, which is made by assembling iron wire rods 15 in a lattice shape, and constitutes the rope-like member ■. One end side of the iron wire rod 15 is brought into contact with the rock-side bar 5 of the shoring main body (■), the tip end thereof is bent, and the tip end is attached to the rock-side bar 5 of the shoring body ■.
(and/or the connecting member 6). 7 in the figure indicates a connecting flange used when assembling the shoring together along the inner circumferential wall of the tunnel. When this net-like integrated shoring is installed in contact with the ground 3, the underground 3 is supported by the shoring body I, and the collapse of earth and sand from the exposed surface of the ground is supported by the mesh material ■. As a whole, the ground 3 remains stable.

The number and diameter of the bars 5 that make up the shoring body I are as follows:
It is the same as the earlier invention in that it can be changed as appropriate depending on the degree of ground pressure applied to the support, and the structure and attachment of the connecting member 6, such as the pitch, can also be changed as necessary. be. In addition, the material of the wire rods constituting the net-like member ■ is most commonly iron-steel, but the rods constituting the shoring body 5
Of course, it is also possible to use various materials as described above. This net-like member (2) is used to prevent the collapse of earth and sand from the surface of the ground before spraying concrete, and after spraying concrete, it functions as a support and reinforcing reinforcement for the concrete. Wire rod 15
The thickness, mesh pitch, etc. may be appropriately increased or decreased depending on the softness of the ground 3, etc.

FIG. 4 is a perspective view showing another embodiment of the present invention, and FIG. 5 is a cross-sectional view corresponding to the v-v line in FIG. Four bars 5, 5... are bent into a rectangular shape and constitute the shoring body I.
15b in Figure 0 indicates the transverse reinforcement.

With such a configuration, not only can the integrity of the shoring body I and the mesh member (2) be further improved, but also it is advantageous because no special work is required to assemble the two.

FIG. 6 is a partial cross-sectional view illustrating a tunnel wall structure constructed using the net-like member integrated shoring of the present invention. 4 in Figure 0, which functions as a reinforcing material.
3 indicates an anchor bolt for increasing the integrity of the ground 3 and the concrete layer 2, and 8 indicates an anchor pin driven in for fixing the mesh member (2) as necessary.

[Effects of the Invention] Since the present invention is configured as described above, the bar support according to the prior invention has the following effects: (1) It is possible to install it in close contact with the tunnel excavation surface; (2) Shotting does not cause concrete filling defects, and it is possible to form a reinforced wall with no connected defects in the length direction of the tunnel. (3) Support with necessary and sufficient strength according to geological changes in the ground and load conditions. (5) By integrating the rock bolts and the shoring, the strength of the tunnel wall can be mutually increased. I can do it.

(8) There is little splashing of shotcrete. (7) It is lightweight and has excellent workability and handling.In addition, the mesh member is formed integrally with the shoring body, which greatly simplifies construction work. , enabling quick construction. Furthermore, the shoring body, the mesh member, and the sprayed concrete can be integrated to form an even stronger tunnel reinforcement wall.

[Brief explanation of the drawing]

Figures 1 to 3 illustrate the net-like member integrated shoring according to the present invention, where Figure 1 is a front view, Figure 2 is a plan view, and Figure 3 is a sectional view taken along line mm in Figure 1. , FIG. 4 is a sketch showing another embodiment of the present invention, and FIG. 5 is a diagram showing v- in FIG. 4.
6 is a partial sectional view illustrating a reinforced wall obtained using the shoring of the present invention, and Figure 7.8 shows the problems when using conventional H-shaped steel shoring. 7 is a partial cross-sectional view, FIG. 8 is a schematic vertical cross-sectional view, and FIGS. 9 to 18 illustrate the bar shoring according to the invention of the prior application.
11-16 are cutaway perspective views of essential parts, FIG. 1O is a schematic perspective view, and FIGS. 17 and 18 are cross-sectional views. Work...Bar shoring body ■...Mesh member 2...
Spraying is concrete

Claims (1)

[Claims] A net-like structure characterized in that two or more rods are arranged substantially in parallel and assembled together with at least one connecting member to form a tunnel shoring, and a net-like member is integrally joined to the shoring. Shoring for tunnels with connected parts.