JP7595329B1 - Construction method of guide tunnel and steel protective shelter structure - Google Patents

Abstract

To provide a method for constructing guide pilot tunnels that can be easily, quickly, and safely constructed.
[Solution] A steel protective shelter consisting of a front blade section, a thrust jack installation section, and a support assembly section is used, and both the steel protective shelter and the support have the outer circumference of a lotus petal or horseshoe shape, and the support is a half-assembled type with this lotus petal or horseshoe shape.The support is gradually extended by repeating the process of excavating with the front blade section of the steel protective shelter, thrusting the steel protective shelter with a thrust jack in the thrust jack installation section, and assembling the support in the support assembly section of the steel protective shelter.
[Selected Figure] Figure 1

Description

The present invention relates to a method for constructing guide tunnels, which are small tunnels excavated at the location that will become the tunnel base prior to the construction of tunnels such as box culverts directly beneath railway tracks or roads.

Guide pilot tunnels are also shown in the following patent document, and as shown in Figure 15, a protective pipe roof 3 is constructed between a starting shaft 21 and a arrival shaft 22, and a guide pilot tunnel 6 is excavated at a position that will become the bottom slab of the tunnel.
JP 2002-242582 A

The guide tunnel 6 can be constructed by a known tunnel excavation method. For example, a tunnel can be constructed by repeating the steps of assembling shoring → erecting sheet piles → excavation → assembling shoring using the sheet pile method.

The concrete box 5 is constructed inside the starting shaft 21, and a frame material 8, which serves as a back frame, is attached to the end of the concrete box 5 opposite the excavation direction, i.e., the rear end. In addition to constructing such a concrete box 5 as a cast-in-place RC box, it may also be a precast factory-made concrete box or a steel segment box.

One end of the towing member 71 is fixed to a fixed point 91 provided, for example, on the side of the arrival shaft 22, and the other end is attached to the frame material 8 via a towing jack 73.

The traction member 72 installed below the tunnel is inserted into the guide tunnel 6. Like the traction member 71 installed above, the traction member 72 installed below has one end fixed to a fixed point 92 and the other end attached to the frame material 8 via a traction jack 73.

The concrete box body 5 is towed to the guide pilot tunnel construction ground 1. The concrete box body 5 is towed by combining digging with an excavator or the like at the front side of the concrete box body 5 (the surface in contact with the ground) and towing the concrete box body 5 by operating a jack 73.

The above describes the case of the towing method, but the pushing method is also possible. As shown in Figure 16, a pushing jack 74 is installed in the starting shaft 21, and the concrete box body 5 is pushed by this pushing jack 74. Prior to this, a box-shaped roof 76 is installed in place of the protective pipe roof 3.

The box-shaped roof 76 has small jacks 77 housed in jack housing pipes at the base, and each jack is used to excavate the concrete box 5 using reaction force, causing the concrete box 5 to be excavated.

In the figure, 75 is a reaction wall installed in the departure shaft 21, and 78 is a support for the box-shaped roof 76 installed in the arrival shaft 22.

As described above, the guide pilot tunnel 6 is constructed by a known tunnel excavation method, and the guide pilot tunnel is constructed while erecting the steel shoring by the sheet pile method. The sheet pile method is a method in which the excavated ground is supported by steel shoring and sheet piles, and the shoring is erected after excavation and removal of debris, but this is done under the bare ground behind the site for about 1m in a section where the steel shoring is not installed and generally reinforces the ground behind the site by ground improvement such as chemical injection work, but it lacks workability and safety.

The object of the present invention is to provide a method for constructing guide tunnels and a steel protective shelter structure that can eliminate the inconveniences of the above-mentioned conventional examples and can be constructed easily, quickly, and safely.

In order to achieve the above-mentioned object, the present invention described in claim 1 uses a steel protective shelter consisting of a front cutting edge section that is tapered to form a hood so that the upper part of the tip surface juts out to prevent the collapse of the face , a thrust jack installation section, and a support assembly section, and both the steel protective shelter and the support have the outer circumference of a lotus petal or horseshoe shape, and the support is a half-assembled type with this lotus petal or horseshoe shape, and the gist of the invention is that the front cutting edge section of the steel protective shelter is used to excavate, the steel protective shelter is thrust with a thrust jack in the thrust jack installation section, and the support is assembled in the support assembly section of the steel protective shelter, and the process is repeated to gradually extend the support.

According to the present invention described in claim 1, a guide tunnel is constructed using a steel protective shelter consisting of a front cutting edge section, a thrust jack installation section, and a support assembly section, and since the support can be assembled using the support assembly section of the steel protective shelter, construction can be carried out safely and quickly.

Furthermore, both the steel protection shelter and the shoring have a lotus petal or horseshoe shaped outer circumference, and the shoring can be easily assembled in the shoring assembly section of the steel protection shelter.

The gist of the present invention described in claim 2 is that a half-assembled support with a lotus petal or horseshoe-shaped external shape is constructed by erecting one side first, temporarily supporting it, erecting the other side, and bolting the tops together to form a ring.

According to the present invention described in claim 2, the shoring can be easily assembled in the shoring assembly section of the steel protective shelter, and the shoring can be assembled more safely because one side of the shoring is erected first, temporarily supported, and the other side is erected and the tops are bolted together to form a ring.

The present invention as described in claim 3 has the gist that by forming a tapered hood, the amount of over-excavation is reduced, and by advancing the cutting edge and the steel protective shelter as a single unit without erecting support structures at the face in front of the cutting edge, the section of the ground exposed behind the guide tunnel at the rear of the shelter is significantly reduced .

According to the present invention as described in claim 3, by sequentially advancing the steel protective shelter in accordance with excavation, the section of exposed ground behind the guide tunnel can be kept to approximately 0.2 m, allowing safe excavation of the face.

The present invention described in claim 4 is a steel protective shelter used in the construction method of the guide tunnel described in claim 1 , which has a lotus petal or horseshoe shape with a tapered tip, and a three-part structure assembled by bolting together the cutting edge section, the thrust jack installation section and the support assembly section, with the support assembly section having a bottom slab only at the front and the rear half being open at the bottom.

According to the present invention as set forth in claim 4, the steel protective shelter is lotus petal shaped with a tapered tip, which increases the strength of the tip and improves excavation performance.

In addition, the support assembly section has a bottom slab only at the front, while the rear half is open at the bottom, exposing the ground. The support is assembled in the rear part of the shelter where the ground is exposed. In order to ensure space for assembly of the support, no reinforcing members are provided in the support assembly section, and removable reinforcing members with built-in jacks can be placed as support beams to prevent deformation. This makes it possible to narrow the gap between the inner surface of the steel protective shelter and the support and reduce the amount of backfill injected, ensuring safety during excavation and improving workability.

By installing removable reinforcement materials in the support assembly section inside the steel protective shelter, deformation of the steel protective shelter due to earth pressure in the guide pilot tunnel can be suppressed without installing reinforcing materials, and since the support can be assembled close to the inner surface of the steel protective shelter, the backfill thickness can be kept to around 50 mm, minimizing ground excavation and reducing the amount of backfill injected.

As described above, the guide tunnel construction method and steel protective shelter structure of the present invention allow for the construction of guide tunnels easily, quickly, and safely.

FIG. 2 is a vertical cross-sectional side view showing one embodiment of a guide tunnel construction method of the present invention. FIG. 2 is a vertical cross-sectional side view showing an excavation state illustrating one embodiment of the guide tunnel construction method of the present invention. This is a vertical cross-sectional side view of the front end cutting edge of the steel protective shelter. This is a vertical cross-sectional side view of the propulsion jack installation section of the steel protective shelter. This is a longitudinal side view of the support assembly part of the steel protective shelter. FIG. 4 is a view taken along line A in FIG. 3 . FIG. 5 is a view taken along line B in FIG. 4 . FIG. 6 is a view taken along line C in FIG. 5 . FIG. 2 is a cross-sectional plan view of a completed embodiment of a guide tunnel construction method according to the present invention. This is a front view of the first step showing the procedure for erecting the support structure. A front view of the second step showing the procedure for erecting the support structure. A front view of the third step showing the procedure for erecting the support structure. A front view of the fourth step showing the procedure for erecting the support structure. This is a front view of wooden sheet piles installed on the support structure. FIG. 2 is a vertical cross-sectional side view showing an example of a guide tunnel. FIG. 11 is a vertical cross-sectional side view showing another example of a guide tunnel.

The following describes in detail an embodiment of the present invention with reference to the drawings. Figure 1 is a vertical cross-sectional side view showing one embodiment of the guide tunnel construction method of the present invention, in which 21 is the starting shaft and 2 is a steel protective shelter.

The construction method of the present invention uses a steel protective shelter 2 to construct a guide tunnel. The steel protective shelter 2 is a steel shell with an outer periphery having a lotus petal or horseshoe shaped cross section.

The steel protective shelter 2 can also be divided to make installation and removal easier. This figure shows a structure divided into three parts: the front cutting edge section 2a, the propulsion jack installation section 2b, and the support assembly section 2c, which are assembled using flange bolt joints, etc.

Of these, the front cutting edge portion 2a has a tapered hood with an upwardly projecting tip surface as shown in FIG. 3 in order to prevent the face from collapsing, so that excavation can be performed with a slope at the face.

In addition, by tapering the hood to form a hood, the amount of overexcavation can be reduced, and by advancing the cutting edge and the steel protective shelter as a single unit without erecting support structures at the face in front of the cutting edge, the area where the guide tunnel ground is exposed behind the shelter can be significantly reduced .

The propulsion jack installation section 2b has four installation stands 7 for the propulsion jacks 4 installed inside as horizontal brackets.

The front cutting edge section 2a and the propulsion jack installation section 2b are both closed-type steel shells with a bottom plate 9, while the support assembly section 2c has a bottom plate only at the front and the rear half at the back is open on the bottom, exposing the ground. The support described below is assembled at the location where the ground is exposed.

In addition, in order to secure space for assembling the shoring, the reinforcing member 8 is not provided in the shoring assembly section 2c, but a removable reinforcing member 10 with a built-in jack can be placed as a support beam to prevent deformation. This narrows the gap between the inner surface of the steel protective shelter and the shoring, and reduces the amount of backfill injected.

In addition, lighting (LED) 11a and lighting (fluorescent lamp) 11b were installed inside the steel protective shelter 2.

The thrust reaction body 12 is formed from steel and brackets in the starting shaft 21, and the steel protective shelter 2 is excavated in sequence with the struts (for thrust construction) 13 in between. This excavation is carried out by digging the face of the front cutting edge part 2a by hand or with a small backhoe or shaft loader, and the excavated soil is sent to the rear with a trolley 17. The thrust jack 4 is extended to excavate the steel protective shelter 2, and the struts 13 are added to the void created by the thrust jack 4 being retracted.

The shoring 14 is assembled in the shoring assembly section 2c of the steel protective shelter 2. This allows the shoring to be assembled in a space protected by the steel protective shelter, making it possible to safely assemble the shoring. When assembled, the shoring 14 has an outer periphery with a lotus petal or horseshoe shape, just like the steel protective shelter 2, and is a combination of shoring material 14a and shoring material 14b that curve together to form a shoring ring.

Figures 10 to 13 show the procedure for erecting this shoring 14. One side of the shoring material 14a is erected first at the shoring assembly section 2c of the steel protective shelter 2, and this is temporarily supported by a temporary support material 15 such as a pipe. The other side of the shoring material 14b is then erected and the tops are secured together with bolts, and a strut (shoring material) 16 is placed across the bottom ends to form a ring.

The supports 14 are arranged at intervals, and wooden sheet piles 18 are attached to the outside as shown in Figure 13. The wooden sheet piles 18 arranged at the top are equipped with packers 19.

The steel protective shelter 2 is excavated in stages, and the section where the ground is exposed is reduced to about 0.2 m, allowing excavation to be carried out while suppressing the collapse of the ground in the tunnel, and backfill material 20 is injected through the gaps in the wooden sheet piles 18 of the support 14 protruding from the support assembly section 2 c of the steel protective shelter 2.

The timing of excavation of the steel protective shelter 2 and assembly of the shoring 14 is as follows: after two rings of shoring 14 have been constructed and some of the wooden sheet piles 18 have been placed, excavation of the steel protective shelter 2 is carried out, and when the shoring 14 has left the shoring assembly section 2c of the steel protective shelter 2, the remaining wooden sheet piles 18 are placed and the backfill material 20 is injected.

Instead of injecting the backfill material 20, backfill soil may be used to fill the gap.

In this way, the support structure is gradually extended as the steel protective shelter 2 is excavated, and a guide tunnel is constructed.

In addition, a steel protective shelter will be gradually advanced along the front cutting edge as excavation progresses, significantly reducing the area where the ground behind the guide tunnel is exposed.

This allows the steel protective shelters to be advanced in sequence as excavation progresses, keeping the section of exposed ground behind the guide tunnel to around 0.2 m, allowing for safe excavation of the face.

In addition, the gap between the back of the support and the ground behind the guide pilot tunnel is reduced . This allows the installation of removable reinforcement materials in the support assembly section inside the steel protection shelter, making it possible to suppress deformation of the steel pilot shelter due to the earth pressure of the guide pilot tunnel without the need for reinforcement materials, and since the support can be assembled close to the inner surface of the steel protection shelter, the backfill thickness can be kept to about 50 mm, minimizing excavation of the ground and reducing the amount of backfill injection.

Figure 9 shows the completed form, but once the steel protective shelter 2 reaches the arrival shaft 22, it is retrieved.

Reference Signs List 1: Guide pilot tunnel construction ground 2: Steel protective shelter 2a: Front end cutting edge 2b: Thrust jack installation section 2c: Support assembly section 3: Protective pipe roof 4: Thrust jack 5: Concrete box body 6: Guide pilot tunnel 7: Jack receiving member 8: Frame material 9: Bottom plate 10: Detachable reinforcement material 11a: Lighting (LED)
11b... Lighting (fluorescent lamp) 12... Thrust reaction body 13... Strut (for thrusting work) 14... Support 14a... Support material 14b... Support material 15... Temporary support material 16... Strut (support material)
17 ... Dolly 18 ... Wooden sheet pile 19 ... Packer 20 ... Backfill material 21 ... Starting shaft 22 ... Arrival shaft 71, 72 ... Towing member 73 ... Towing jack 74 ... Pushing jack 75 ... Reaction wall 76 ... Box roof 77 ... Small jack 78 ... Support stand

Claims (4)

A steel protective shelter is used, consisting of a front cutting edge section with a tapered hood formed by protruding at the top of the tip to prevent the collapse of the face, a thrust jack installation section, and a support assembly section, and both the steel protective shelter and the support have the outer circumference of a lotus petal or horseshoe shape, and the support is a half-assembled type with this lotus petal or horseshoe shape.This guide tunnel construction method is characterized by gradually extending the support by repeating the process of excavating with the front cutting edge section of the steel protective shelter, thrusting the steel protective shelter with the thrust jack in the thrust jack installation section, and assembling the support in the support assembly section of the steel protective shelter. The construction method for a guide tunnel as described in claim 1, in which a half-assembled support with a lotus petal or horseshoe-shaped external shape is erected on one side, which is temporarily supported, and then the other side is erected and the tops are bolted together to form a ring. A method of constructing a guide tunnel as described in claim 1 or claim 2, in which the amount of over-excavation is reduced by forming a hood with a taper, and the cutting edge and the steel protective shelter are advanced together without erecting support work at the face in front of the cutting edge, thereby significantly reducing the area where the ground behind the guide tunnel is exposed at the rear of the shelter. A steel protective shelter used in the construction method of the guide tunnel of claim 1 , characterized in that it has a lotus petal or horseshoe shape with a tapered tip, and is divided into three parts by assembling the cutting edge section, the thrust jack installation section and the support assembly section with bolt connections, and the support assembly section has a bottom slab only at the front and the rear half is open at the bottom.

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