JP7557255B2 - Lining concrete pouring method - Google Patents

Description

The present invention relates to a method for pouring lining concrete, and in particular to a technology that is effective when applied to pouring lining concrete in the construction of mountain tunnels.

In the construction of mountain tunnels, a blasting method is used in which dynamite is planted in the bedrock and then exploded to excavate the tunnel. This method involves spraying concrete into the excavated area, allowing it to harden, and installing rock bolts in the bedrock, using the natural holding power of the ground to hold the tunnel in place. After the rock bolts are installed, a semi-cylindrical formwork called a center is fitted into the excavated area, and lining concrete is poured (filled) between the sprayed concrete and the center to complete the construction.

Here, air bulk is used to prevent concrete from leaking out from the gable side of the center hole when filling the gap between the center hole and the shotcrete (pouring the lining concrete).

That is, as shown in Figure 11, which is a cross-sectional view in the tunnel extension direction, and Figure 12, which is a cross-sectional view along line Z-Z in Figure 11, the center C is equipped with an inner formwork Ca arranged opposite the shotcrete 12 through which the rock bolt B is inserted, and a flange Cb installed on the gable side of the inner formwork Ca so as to protrude outside the inner formwork Ca in the tunnel crossing direction. An air bulk AB that is not filled with air is installed on top of the inner formwork Ca on the flange Cb side, and air is filled into the air bulk AB to expand it and bring it into close contact with the shotcrete 12, and lining concrete is poured into the space 13g between the inner formwork Ca and the shotcrete 12.

In addition, if the gap between the gable side of the inner formwork Ca and the sprayed concrete 12 becomes too large, multiple air bulks AB are stacked on top of each other to seal the gap, as shown in the figure.

In Figures 11 and 12, symbol G denotes the ground, symbol S denotes the steel support, and symbol 11 denotes the temporary sprayed concrete used to hold the steel support S.

One example of a technique that describes tunnel construction using air bulk is known from Patent Document 1 (JP Patent Publication No. 2017-223013).

JP 2017-223013 A

However, the construction method using the air bulk AB described above has the following problems:

In other words, when the air bulk AB is expanded, its shape becomes cylindrical. When the air bulk AB is used in a stacked manner, a cylindrical air bulk AB is placed on top of another cylindrical air bulk AB, and when considered in cross section of the air bulk AB, a curved surface is supported by a curved surface, as shown in Figure 11. This reduces the contact area between the air bulks AB, making the installation unstable and reducing workability.

In addition, the air bulks AB are long and about 4 m long, making them heavy (for example, an air bulk with a diameter of 150 mm weighs about 6 kg, and an air bulk with a diameter of 200 mm weighs about 8 kg), making it extremely difficult to install them in the transverse direction on the inner formwork Ca of the center C.

The present invention was made in light of the above technical background, and aims to provide a method for pouring lining concrete that can easily prevent concrete from flowing out from the gable side of the center when pouring the lining concrete between the inner formwork of the center and the shotcrete.

In order to solve the above problems, the method of pouring lining concrete of the present invention described in claim 1 is a method of pouring lining concrete in the construction of a mountain tunnel, characterized in that a center having an inner formwork extending in the extension direction of the tunnel and curved in the transverse direction of the tunnel and a flange installed on the gable side of the inner formwork so as to protrude outward in the transverse direction of the tunnel is installed at a position where the sprayed concrete is poured, a layer of elongated air bulk without air is installed on the inner formwork side between the inner formwork and the shotcrete along the flange, and then at least one layer of extruded polystyrene foam, which is a elongated plate-shaped member having a predetermined thickness, is installed on top of the air bulk in accordance with the gap between the inner formwork and the shotcrete, and then the air bulk is expanded to close the gap between the inner formwork on the gable side and the shotcrete, and the lining concrete is poured into the space formed by the inner formwork and the shotcrete.

The method of pouring lining concrete of the present invention described in claim 2 is characterized in that, in the invention described in claim 1 , notches are formed at predetermined intervals on one or both sides of the extruded polystyrene foam along the extension direction of the tunnel.

The method of pouring lining concrete of the present invention described in claim 3 is characterized in that, in the invention described in claim 1 or 2 , the extruded polystyrene foam has been subjected to a peeling treatment to improve its peelability from the hardened lining concrete.

The method of pouring covering concrete of the present invention described in claim 4 is characterized in that, in the invention described in claim 3 , the peeling treatment is a treatment of wrapping the entire extruded polystyrene foam in the short direction with adhesive tape having a release agent surface, or a treatment of applying a release agent to the entire extruded polystyrene foam.

According to the present invention, the extruded polystyrene foam has a flat shape in the extension direction of the tunnel , so that the air bulk is stable and workability is improved.

In addition, the use of extruded polystyrene foam, which is lightweight and easy to handle, improves workability during installation.

This makes it easy to prevent concrete from leaking out from the gable side of the center column when pouring lining concrete between the center column's inner formwork and the shotcrete.

1A is a plan view of a continuous belt conveyor system used in the construction of a mountain tunnel in accordance with this embodiment, and FIG. 1B is a side view of the continuous belt conveyor system of FIG. 1A. 1 is a flowchart outlining the construction of a mountain tunnel. 1A to 1D are explanatory diagrams showing the sequence of pouring of lining concrete in the construction of a mountain tunnel in this embodiment. 1 is a cross-sectional view in the direction of tunnel extension, including an anti-flow member according to one embodiment of the present invention, which is installed when pouring lining concrete in the construction of a mountain tunnel. 5 is a cross-sectional view taken along line WW in FIG. 4. FIG. 1A is an oblique view showing the extruded polystyrene foam used in the outflow prevention member of this embodiment, FIG. 1B is an oblique view showing the extruded polystyrene foam of FIG. 1A with a notch formed on one side, and FIG. 1C is an oblique view showing the extruded polystyrene foam of FIG. 1A with a notch formed on both sides. 1 is a cross-sectional view in the tunnel extension direction including a flow prevention member according to another embodiment of the present invention, which is installed when pouring lining concrete in the construction of a mountain tunnel. 8 is a cross-sectional view taken along line XX in FIG. 7. 1 is a cross-sectional view in the tunnel extension direction including a flow prevention member as yet another embodiment of the present invention, which is installed when pouring lining concrete in the construction of a mountain tunnel. 10 is a cross-sectional view taken along line YY in FIG. 9. FIG. 1 is a cross-sectional view in the direction of tunnel extension, including a conventional anti-flow member that is installed when pouring lining concrete in the construction of a mountain tunnel. 12 is a cross-sectional view taken along line Z-Z in FIG. 11.

Below, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings for explaining the embodiment, the same components are generally designated by the same reference numerals, and repeated explanations will be omitted.

The method of pouring lining concrete in this embodiment is particularly applicable to pouring lining concrete in mountain tunnel construction.

In mountain tunnel construction, a blasting method is used, in which dynamite is planted in the rock and then exploded to excavate the tunnel. This method involves spraying concrete into the excavated area, allowing it to harden, and then installing rock bolts in the rock, using the natural holding power of the ground to hold the tunnel in place. This method is called NATM (New Australian Tunneling Method).

First, an example of the configuration of a continuous belt conveyor system used in the construction of a mountain tunnel according to this embodiment will be described with reference to FIG. 1. Here, FIG. 1(a) is a plan view of a continuous belt conveyor system used in the construction of a mountain tunnel according to this embodiment, and FIG. 1(b) is a side view of the continuous belt conveyor system of FIG. 1(a).

The illustrated continuous belt conveyor system 1 is a system for transporting the debris (excavated material) generated when the face K of the tunnel T is excavated by blasting to the mouth of the tunnel T, and a crusher 2, a tailpiece cart 3, and a belt conveyor 4 are arranged in a vertical line in that order from the face K to the mouth.

The crusher 2 is a self-propelled crusher that crushes the rubble generated by blasting into a size that can be transported by the belt conveyor 4. The tailpiece cart 3 is a self-propelled relay transport device that transports the rubble crushed by the crusher 2 to the belt conveyor 4, and is installed at the end of the belt conveyor 4 (i.e., the face K side of the belt conveyor 4). The belt conveyor 4 is a transport device that loads the rubble transported via the tailpiece cart 3 onto a long transport belt 4a and transports it toward the mouth of the tunnel T, and is installed in a state where it extends continuously from the rear end of the tailpiece cart 3 to the mouth side of the tunnel T. Furthermore, the continuous belt conveyor system 1 is equipped with a belt storage 5 that stores the excess belt (stretching belt) and provides the belt 4a with an appropriate tension.

In addition to the above, the continuous belt conveyor system 1 also includes a belt joint stand (not shown) for joining belt 4a when the excess belt stored in the belt storage 5 runs out, a main drive (not shown) which is the main driving device for driving belt 4a in a circular motion, a booster drive (not shown) which drives belt 4a in the daytime portion of the belt conveyor 4, and ventilation and electrical equipment (not shown) for controlling each device.

The continuous belt conveyor system 1 is also moved to one side of the tunnel T in the width direction, and the other side of the tunnel T in the width direction can be used as a passage for various heavy machinery such as a spraying machine (not shown) for spraying concrete on the excavated rock wall, a face drilling machine (not shown) for drilling holes (charge holes) in the face K for loading blasting, a self-propelled side dump 7 equipped with a shovel 7a for loading rubble generated by blasting onto the crusher 2, a backhoe, and a breaker (not shown) for crushing, excavating, and breaking the rock into smaller pieces. In addition, a material storage area (not shown) for storing rock bolts, steel supports, and the like is allocated to the work site.

In the continuous belt conveyor system 1, during blasting, the tip of the crusher 2 located at the front is positioned so that it cannot be reached by debris scattered from the face K. This makes it possible to prevent damage to the crusher 2, tailpiece cart 3, and belt conveyor 4 caused by debris scattered from the face K during blasting. Then, when transporting the debris after blasting, the side dump 7 moves toward the face K, and the excavated debris is dumped into the crusher 2 by the shovel 7a.

In FIG. 1(b), the dotted lines extending left and right indicate the area of the shotcrete in the longitudinal direction of the tunnel T, and the symbol B indicates a rock bolt installed in the concrete. The shotcrete and rock bolt B will be described later.

Next, we will explain the outline of mountain tunnel construction using the flowchart in Figure 2.

First, as described above, holes are drilled in the face to prepare explosives (step St01), explosives are loaded (step St02), and blasting excavation is performed (step St03). Then, the debris is removed (step St04).

Next, it is determined whether or not to install steel supports S (Figs. 4, 6, 9) based on the condition of the rock (step St05). If steel supports S are to be installed, concrete is temporarily sprayed (step St06) and the steel supports S are erected (step St07). If the steel supports S are erected in step St07, concrete is sprayed onto the surface of the temporarily sprayed concrete, or directly onto the surface of the natural ground G (Figs. 4, 5, 7-10) if the steel supports S are not to be installed in step St05 (step St08), and rock bolts B (Figs. 4, 6, 9) are installed (step St09).

In this application, concrete sprayed when installing steel shoring S is referred to as temporary shotcrete 11 (Figs. 4, 5, 7-10), and concrete sprayed onto the surface of the ground G without installing temporary shotcrete 11 or steel shoring S is simply referred to as shotcrete 12 (Figs. 4, 5, 7-10). In this application, it is assumed that the steel shoring S has been erected, and that the shotcrete 12 is sprayed onto the temporary shotcrete 11. However, this does not exclude the possibility of spraying the shotcrete 12 directly onto the ground G without erecting the steel shoring S.

Now, once the rock bolt B has been installed in step St09, a waterproof sheet is applied as necessary to prevent water leakage into the tunnel, a center is fitted, and lining concrete is poured between the shotcrete 12 applied in step St08 and the center, for finishing work (step St10). Note that the pouring of lining concrete is carried out, for example, every other day. Then, it is determined whether the series of work has been completed (step St11), and if so, the construction of the tunnel is terminated. Also, if the work has not been completed in step St11, the process returns to step St01 and the subsequent steps are repeated.

Now, the pouring of the lining concrete 13 will be explained with reference to Figure 3. As shown in the figure, the center C is a semi-cylindrical formwork that can be moved on a steel rail (not shown) in order to pour the lining concrete 13 into the shotcrete 12 portion of the tunnel T. As shown in the figure, the center C has an inner formwork Ca that extends in the extension direction of the tunnel T and curves in the transverse direction of the tunnel T, and a flange Cb that is installed on the end side of the center C so as to protrude outward in the transverse direction of the tunnel. Then, while the center C is being moved, the lining concrete 13 is poured into the space 13g between the center C and the shotcrete 12.

That is, as shown in FIG. 3(a), the inner formwork Ca of the center C is moved to the pouring position for the lining concrete (i.e., the position where the shotcrete 12 is poured), and then, as shown in FIG. 3(b), a flange Cb is attached to the gable side of the inner formwork Ca. Next, to prevent the poured concrete from flowing out of the gable side of the center C, as shown in FIG. 3(c), a flow prevention member 14 (details will be described later) is installed between the inner formwork Ca along the flange Cb and the shotcrete 12 to block the gap between the inner formwork Ca on the gable side and the shotcrete 12. Then, as shown in FIG. 3(d), the lining concrete 13 is poured into the space 13g formed by the inner formwork Ca and the shotcrete 12.

Here, even if the outflow prevention member 14 is pressed by the lining concrete 13 when pouring and filling the lining concrete 13, the side of the outflow prevention member 14 is pressed against the flange Cb to prevent movement, so the outflow prevention member 14 will not fall from the end side of the center C. In this way, the flange Cb functions to support the outflow prevention member 14 so that it does not fall from the end side of the center C when pouring the lining concrete 13.

When pouring the lining concrete 13, as shown in FIG. 3(d), the concrete is poured from the bottom up, and finally the concrete is sprayed up and poured into the ceiling. In this embodiment, the length of the lining concrete 13 poured at one time is, for example, about 10 to 15 m, and the thickness of the lining concrete 13 is, for example, 30 cm or more. However, the numerical values of the lining concrete 13 in this invention are not limited to these.

In addition, in this embodiment, the flange Cb is attached to the inner formwork Ca, but the inner formwork Ca and the flange Cb may be integrated, so that the attachment of the flange Cb can be omitted.

Next, the anti-flow member 14 that is installed when pouring the lining concrete 13 will be explained using Figures 4 to 10.

Figure 4 is a cross-sectional view in the tunnel extension direction including an anti-flow member according to one embodiment of the present invention that is installed when pouring lining concrete in mountain tunnel construction, Figure 5 is a cross-sectional view taken along line W-W in Figure 4, and Figure 6 is a perspective view showing the extruded polystyrene foam used in the anti-flow member.

As shown in Figures 4 and 5, the outflow prevention member 14 is made by installing an extruded polystyrene foam PF, which is a long plate-like member having a predetermined thickness, and expanding a long air bulk AB. The extruded polystyrene foam PF is installed on the inner formwork Ca side, and the air bulk AB is installed on the sprayed concrete 12 side.

Here, extruded polystyrene foam PF is a plate-shaped member made by dissolving polystyrene, mixing it with a foaming agent and a flame retardant, and extruding it into a plate shape (see Figure 6 (a)). This extruded polystyrene foam PF can be processed to the desired size during the manufacturing process, and can also be easily cut at the work site. In addition, it has high insulation performance, is resistant to water and moisture, and is lightweight, making it easy to handle. The extruded polystyrene foam PF has a length of 910 mm, a width of 225 mm, and a thickness of 50 mm, but the dimensions are not particularly limited.

In this embodiment, three layers of extruded polystyrene foam PF are installed along the inner formwork Ca (i.e., the longitudinal direction of the extruded polystyrene foam PF is the circumferential direction of the tunnel T), and one layer of air-free air bulk AB is placed on top of them (i.e., on the sprayed concrete 12 side) and allowed to expand, thereby utilizing the expansion of the air bulk AB to seal the space between the inner formwork Ca on the gable side and the sprayed concrete 12 with the air bulk AB and the extruded polystyrene foam PF.

Including Figures 7 and 8 described below, three layers of extruded polystyrene foam PF are installed, but three layers are not necessary. In other words, the number of extruded polystyrene foam PF installed is determined according to the thickness of one sheet of extruded polystyrene foam PF, the diameter of the air bulk AB when expanded, and the distance between the inner formwork Ca on the gable side and the sprayed concrete 12, so it is not necessary to install three layers, and it is sufficient to install at least one layer. However, only one layer of air bulk AB is installed.

Depending on the length of the inner formwork Ca in the tunnel transverse direction and the length of the extruded polystyrene foam PF, one sheet of extruded polystyrene foam PF may be sufficient to arrange one layer, or multiple sheets may be required. Similarly, one sheet of air bulk AB may be sufficient to arrange one layer, or multiple sheets may be required.

In this embodiment, the extruded polystyrene foam PF has a flat shape in the extension direction of the tunnel T, so by stacking the extruded polystyrene foam PF and the air bulk AB, a curved surface is no longer supported by a curved surface as occurs when a cylindrical air bulk AB is placed on top of a cylindrical air bulk AB (see Figure 11), making the air bulk AB stable and improving workability.

In addition, by using extruded polystyrene foam PF, which is lightweight and easy to handle, the use of heavy air bulk AB can be minimized, improving workability during installation.

This makes it easy to prevent concrete from leaking out from the gable side of the center column C when pouring the lining concrete 13 between the inner formwork Ca of the center column C and the shotcrete 12.

In the case shown in Figures 4 and 5, the extruded polystyrene foam PF is installed on the inner formwork Ca side, and the air bulk AB is installed on the sprayed concrete 12 side, so that expansion improves the ability to conform to the unevenness of the sprayed concrete 12, making it possible to more firmly seal the gap between the inner formwork Ca on the gable side and the sprayed concrete 12.

As shown in FIG. 6(a), the extruded polystyrene foam PF can be used as is, but notches PFc along the extension direction of the tunnel T may be formed at predetermined intervals on one side of the extruded polystyrene foam PF as shown in FIG. 6(b), including FIGS. 7 to 10 described below, or on both sides of the extruded polystyrene foam PF as shown in FIG. 6(c). As an example, in the case of the dimensions of the extruded polystyrene foam PF of the present embodiment described above (length 910 mm, width 225 mm, thickness 50 mm), notches PFc with a depth of 10 mm are formed at 30 mm intervals. Also, when forming on both sides, the notches PFc are alternated on both sides.

By forming the notch PFc in this manner, it becomes easier to make the extruded polystyrene foam PF conform to the shape of the inner formwork Ca (the shape of the tunnel T), or, as shown in Figures 7 and 8 described below, if the extruded polystyrene foam PF is placed on the side of the sprayed concrete 12, to the shape of the sprayed concrete 12, making it possible to more firmly seal the gap between the inner formwork Ca on the gable side and the sprayed concrete 12.

In this embodiment, the cross-sectional shape of the notch PFc along the longitudinal direction of the extruded polystyrene foam PF is triangular, but it may be other shapes such as a rectangle.

It is desirable to perform a release treatment on the extruded polystyrene foam PF, including the steps shown in Figures 7 to 10 below, to improve its releasability from the hardened lining concrete 13. Specific examples of the release treatment include wrapping the entire extruded polystyrene foam PF in adhesive tape with a release agent surface, or applying a release agent to the entire extruded polystyrene foam PF.

In this way, the hardened lining concrete 13 adheres to the extruded polystyrene foam PF, preventing the ends of the extruded polystyrene foam PF from tearing off, improving workability when demolding and enabling multiple reuse, improving durability. Also, since extruded polystyrene foam PF is generally cheaper than air bulk AB, costs can be reduced.

When wrapping the extruded polystyrene foam PF with adhesive tape, the tape should be wrapped along the short side of the extruded polystyrene foam PF. By wrapping along the short side, the extruded polystyrene foam PF does not become difficult to bend in the longitudinal direction (i.e., it does not become difficult to bend along the inner formwork Ca), and the strength of the extruded polystyrene foam PF is improved.

In the case shown in Figures 4 and 5, the extruded polystyrene foam PF is installed on the inner formwork Ca side, and the air bulk AB is installed on the sprayed concrete 12 side, but as shown in Figures 7 and 8, the installation positions of the two may be reversed, with the air bulk AB installed on the inner formwork Ca side, and the extruded polystyrene foam PF installed on the sprayed concrete 12 side.

In this way, the heavy air bulk AB is placed on the inner formwork Ca, eliminating the need for workers to lift the air bulk AB to a high position (i.e., the top surface of the extruded polystyrene foam PF), thereby reducing the amount of work required.

Also, as shown in Figures 9 and 10, the gap between the inner formwork Ca on the gable side and the sprayed concrete 12 may be blocked only by extruded polystyrene foam PF, without using air bulk AB. In the illustrated example, three layers of extruded polystyrene foam PF are installed, but three layers are not necessary. In other words, the number of extruded polystyrene foam PF installed is determined according to the thickness of one sheet of extruded polystyrene foam PF and the distance between the inner formwork Ca on the gable side and the sprayed concrete 12, so it is not necessary to install three layers, and it is sufficient to install at least one layer.

In this way, the heavy air bulk AB is no longer necessary, and the space between the inner formwork Ca on the gable side and the sprayed concrete 12 can be sealed using only the relatively lightweight extruded polystyrene foam PF, reducing the amount of work required.

The invention made by the inventor has been specifically described above based on the embodiments, but the embodiments disclosed in this specification are illustrative in all respects and are not limited to the disclosed technology. In other words, the technical scope of the present invention should not be interpreted restrictively based on the explanation in the above embodiments, but should be interpreted strictly according to the claims, and includes technologies equivalent to the technologies described in the claims and all modifications that do not deviate from the gist of the claims.

The above explanation shows the application of the present invention to the sealing between the inner formwork on the gable side of the center tunnel and the shotcrete when pouring the lining concrete, but it can also be applied to the flat insulated lining method (FILM (Flat Insulated Lining Method)). The flat insulated lining method is a method in which the gap between the uneven parts of the shotcrete and the waterproof sheet installed on the inner formwork is filled with a backfill material such as mortar to completely adhere the waterproof sheet, and in this method, the present invention can be applied to the sealing between the inner formwork on the gable side and the shotcrete.

11 Temporary shotcrete 12 Shotcrete 13 Lining concrete 13g Space 14 Outflow prevention member AB Air bulk B Rock bolt C Center Ca Inner formwork Cb Flange G Ground PF Extruded polystyrene foam PFc Notch S Steel support T Tunnel

Claims (4)

A method for pouring lining concrete in the construction of a mountain tunnel, comprising:
The tunnel is then fitted with a concrete splinter, which is located at the end of the tunnel and extends in the direction of the tunnel extension. The concrete splinters are then fitted with a concrete splinter, which is located at the end of the tunnel extension.
A layer of elongated air bulk that does not contain air is placed on the inner formwork side between the inner formwork and the sprayed concrete along the flange, and then at least one layer of extruded polystyrene foam, which is a long plate-shaped member having a predetermined thickness, is placed on top of the air bulk in accordance with the gap between the inner formwork and the sprayed concrete, and then the air bulk is expanded to close the gap between the inner formwork on the gable side and the sprayed concrete,
A lining concrete is poured into the space formed by the inner formwork and the shotcrete.
A method for pouring lining concrete. The extruded polystyrene foam has cutouts at predetermined intervals along the extension direction of the tunnel on one or both sides thereof.
A method for pouring lining concrete according to claim 1. The extruded polystyrene foam is subjected to a release treatment to improve the release property from the hardened lining concrete.
3. A method for pouring lining concrete according to claim 1 or 2 . The peeling treatment is
A treatment of wrapping the entire extruded polystyrene foam along the short side direction with an adhesive tape having a release agent surface;
Or a treatment of applying a release agent to the entire extruded polystyrene foam.
4. A method for pouring lining concrete according to claim 3 .

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