JP6971170B2 - How to build an underground structure - Google Patents

Description

The present invention relates to a method for constructing an underground structure.

When constructing a deep foundation pile, heavy machinery is used to blast rocks and explosives, and the ground is excavated to form an excavation hole. Reinforcing bars, which are structures, are assembled and installed in the excavation holes. The excavation scraps generated when excavating the ground are lifted upward by a crane or vessel and carried out.

After installing the reinforcing bars, the scaffolding is dismantled and removed, and concrete is placed in the excavation holes to construct deep foundation piles. Patent Documents 1 and 2 describe an example in which a suspended scaffold (scaffold) is used as a work scaffold at the time of installing a reinforcing bar or placing concrete.

Japanese Unexamined Patent Publication No. 2002-38475 Japanese Unexamined Patent Publication No. 9-25719

However, in the above-mentioned conventional construction method, the ground excavation process and the reinforcing bar installation process each become a critical path, and it is difficult to shorten the construction period.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for constructing an underground structure capable of shortening the construction period.

The present invention for solving the above-mentioned problems is a method for constructing an underground structure, which comprises a step of constructing a horizontal shaft and a discharge hole for discharging excavated shavings extending upward from the horizontal shaft in the ground, and the discharge. In the process of excavating the ground in the range including the hole, throwing the excavation scrap into the discharge hole and carrying it out from the side shaft, and in the middle of excavating the ground to a predetermined depth, the gantry is suspended at the plane position of the excavation hole. A step of installing the structure of the underground structure on the gantry and a step of excavating the ground to a predetermined depth and then lowering the gantry to set the structure at a predetermined position are provided. It is a method of constructing an underground structure characterized by this.

The structure is, for example, a reinforcing bar, and after setting the reinforcing bar, concrete is placed in the excavation hole, and the reinforcing bar and the gantry are embedded in the concrete.
The underground structure is, for example, a deep foundation pile.

According to the present invention, it is possible to wrap the above-mentioned critical path by installing a structure such as a reinforcing bar and excavating the ground in parallel on the upper and lower sides of the gantry arranged at the plane position of the excavation hole. It is possible to significantly shorten the construction period. After the excavation is completed, the reinforcing bars and the like can be easily set at the required positions simply by suspending the gantry. Further, in the state where the pedestal is in the plane position of the excavation hole, it is difficult to lift the excavation shear to the upper part and carry it out as in the conventional case. It is possible to discharge to the horizontal shaft and carry it out from the horizontal shaft.

In a large-scale underground structure such as a deep foundation pile, the necessary reinforcing bars are also large, but in the present invention, by assembling the reinforcing bars on the gantry in parallel with excavation by the above method, the construction period can be shortened. Connect.

It is desirable that the gantry be suspended according to the progress of excavation of the ground. It is also desirable to install a new structure on the structure after suspending the pedestal.
As described above, in the present invention, not only a scaffold for work, but a pedestal for suspending a structure such as a reinforcing bar is suspended, and the pedestal is suspended according to the progress of excavation, and the reinforcing bar or the like is hung on the pedestal. By adding and installing the reinforcing bars, it becomes possible to suitably perform the parallel work of the installation of the reinforcing bars and the excavation, and the installation work of the reinforcing bars and the like can also be performed on the ground surface.

It is desirable to install a belt conveyor for carrying out excavated shavings in the horizontal shaft.
As a result, the excavation shavings can be suitably carried out in the horizontal pit.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for constructing an underground structure that can shorten the construction period.

The figure explaining the formation of the side shaft 2. The figure explaining the formation of the glory hole 12. The figure which shows the glory hole 12. The figure explaining the excavation of the ground. The figure explaining the installation of the gantry 5. The figure explaining the excavation of the ground and the assembly of the reinforcing bar 6. The figure explaining the excavation of the ground. The figure explaining the set of the reinforcing bar 6. The figure explaining the placing of concrete 17. The figure which shows the deep foundation pile 10a.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

1 to 9 are views showing a method of constructing a deep foundation pile (underground structure) according to an embodiment of the present invention. In this embodiment, an example of forming an excavation hole (shaft) on the slope of a mountain and constructing a deep foundation pile as a foundation of a road pier or the like will be described.

(1. Formation of horizontal shaft)
In the present embodiment, first, as shown in FIG. 1, the horizontal shaft 2 is formed at a depth corresponding to the lower part of the formation range 11 of the deep foundation pile on the slope of the mountain 1. In addition, the slope above the formation range 11 of the deep foundation pile is leveled.

The horizontal shaft 2 is formed so as to reach the formation range 11 of the deep foundation pile on the plane. The side pit 2 is for carrying out the excavation scraps to the outside, and a vibration feeder 21 and a belt conveyor 22 are installed inside. However, heavy machinery such as backhoes are operated in the horizontal pit 2 to carry out the excavation shavings, a dump truck is run in the horizontal pit 2 to carry out the excavation shavings, and the unloading by the belt conveyor 22 and the dump truck are used. It is also possible to carry out at the same time, and various means can be considered for carrying out the excavation shavings from the side pit 2. Further, the horizontal shaft 2 can be used for drainage of groundwater.

(2. Formation of glory hole)
In the present embodiment, next, a cloaca hole (discharge hole) for discharging excavated pile is formed in the formation range 11 of the deep foundation pile. At this time, first, as shown in FIG. 2A, the raise boring machine 3 is installed on the ground surface above the formation range 11 of the deep foundation pile, and the ground is laterally lowered by the bit provided at the tip 32 of the rod 31. Drill up to pit 2.

After that, the tip 32 of the rod 31 is expanded in diameter, and as shown in FIG. 2B, the ground is excavated upward with a bit provided on the upper surface of the enlarged diameter portion while pulling up the rod 31, and the hole is drilled. To expand the diameter.

As a result, as shown in FIG. 3A, a glory hole 12 extending upward from the side shaft 2 in a substantially vertical direction is formed. The excavation scrap generated during the formation of the glory hole 12 falls into the side shaft 2 and is carried out from the vibration feeder 21 to the outside by the belt conveyor 22. From this excavation, it is possible to conduct a preliminary geological survey, such as whether the ground has heavy metals, etc., with high accuracy over the entire depth range of the deep foundation pile, depending on the soil quality at the in-situ.

Further, in the present embodiment, the steel pipe 121 is inserted along the inner surface of the glory hole 12 as shown in FIG. 3B in order to protect the hole wall of the glory hole 12. If necessary, cement milk or the like is filled between the inner surface and the steel pipe 121.

(3. Excavation of the ground)
In the present embodiment, next, as shown in FIG. 4, excavation of the ground is started in the formation range 11 of the deep foundation pile including the glory hole 12. In the present embodiment, the outer edge (wellhead) of the upper end of the excavation hole 13 is reinforced by a guide wall 14 made of concrete or the like, and the ground is excavated by drilling rocks or blasting explosives by the heavy machine 4. In addition, in parallel with the excavation work, the hole wall is protected by spraying concrete.

The excavated excavation generated by excavating the ground is discharged from the excavation hole 13 by throwing it into the glory hole 12, and is carried out from the side pit 2 to the outside in the same manner as described above. Further, the steel pipe 121 of the glory hole 12 is cut and removed in order from the upper part according to the progress of excavation. The above is the same in the subsequent steps.

In the middle of excavating the ground in this way (for example, at the stage of excavating to a depth of about 10 m), in the present embodiment, as shown in FIG. 5A, in the plane position of the excavation hole 13, near the upper end of the excavation hole 13. A pedestal 5 that can be raised and lowered is installed, and as shown in FIG. 5B, the reinforcing bar 6 of the deep foundation pile (structure of the deep foundation pile) is assembled and installed on the pedestal 5. The reinforcing bar 6 is a reinforcing bar cage in which a band bar 62 is provided around the main reinforcing bar 61, but the reinforcing bar 6 is not particularly limited.

The gantry 5 is a pedestal for suspending and lowering the reinforcing bar 6, and is suspended by a suspending material 16 from a suspending device 15 provided on the guide wall 14. The gantry 5 is suspended by a plurality of suspending devices 15 so as to secure a predetermined safety factor, but the configuration of the suspending device 15 and the suspending material 16 is not particularly limited. For example, as the hanging material 16, ordinary wire, PC steel wire, or the like can be used.

The gantry 5 is formed by, for example, assembling steel frames or the like in a grid pattern and providing a net-like flooring material on the frame, and as shown in FIG. 5A, an openable doorway for workers, materials and equipment to enter and exit. 51 is also provided. As a result, it is possible to deal with the failure of the heavy machine 4 and evacuate the worker at the time of blasting.

Further, on the lower surface of the gantry 5, a soundproofing material 53 for preventing construction noise, a lighting device 54 for illuminating a dark place of an excavation hole 13 below the gantry 5, and a sprinkler 55 for dust countermeasures during excavation And a dust collector 56 and the like are provided.

In the present embodiment, as shown in FIGS. 6A and 6B, the gantry 5 is hung down according to the progress of excavation of the ground, the gantry 5 is hung down, and then a new reinforcing bar 6 is placed on the reinforcing bar 6. Add and install, and assemble the reinforcing bar 6 upward. This work can be performed on the ground surface around the excavation hole 13. Further, if necessary, a scaffold for performing work such as protection of the hole wall of the excavation hole 13 is also formed on the gantry 5 so that the work on the gantry 5 can be performed.

When the above steps are repeated and the ground is excavated to a predetermined depth as shown in FIG. 7, the excavation is completed. In the present embodiment, in addition to the above-mentioned deep foundation pile forming range 11, extra digging is performed to a depth of about the thickness of the gantry 5. When the excavation is completed, all the reinforcing bars 6 required for the deep foundation pile are present on the gantry 5 in a completed state. The tip of the horizontal shaft 2 that interferes with the excavation hole 13 is dismantled at an appropriate time during excavation, and the vibration feeder 21 and the belt conveyor 22 installed in the horizontal shaft 2 are also removed at an appropriate time to remove the horizontal shaft. Carry it out from 2.

(4. Placing concrete 17)
After that, the heavy equipment 4 and the like are carried out from the horizontal pit 2 and the gantry 5 is lowered to a predetermined depth (bottom of the excavation hole 13) as shown in FIG. 8 to set the reinforcing bar 6 at a predetermined position. The gantry 5 is arranged in the above-mentioned extra digging portion. The heavy equipment 4 and the like can also be carried upward from the doorway 51 of the gantry 5 described above.

After that, the suspension device 15, the suspension material 16, and the scaffolding and the like are dismantled and removed as necessary, and as shown in FIG. 9, concrete 17 is placed in the excavation hole 13 and the horizontal shaft 2 to form a deep foundation pile. 10 is formed. The deep foundation pile 10 has a configuration such that the horizontal cross sections at each position in the vertical direction have substantially the same shape and size. The concrete 17 in the horizontal shaft 2 may be a concrete having a poorer composition than the concrete in the excavation hole 13. Further, in the present embodiment, in addition to the reinforcing bar 6, the gantry 5 is also embedded in the concrete 17.

As described above, according to the present embodiment, the above-mentioned critical path is wrapped by installing the reinforcing bars 6 and excavating the ground in parallel above and below the gantry 5 arranged at the plane position of the excavation hole 13. It is possible to make it possible to significantly shorten the construction period. After the excavation is completed, the reinforcing bar 6 can be easily set at the required position simply by suspending the gantry 5.

Further, in the state where the gantry 5 is located at the plane position of the excavation hole 13, it is difficult to lift the excavation scrap to the upper part and carry it out as in the conventional case, but in the present embodiment, excavation is performed through the glory hole 12 installed in advance. It is possible to discharge the shear to the lower side pit 2 and carry it out from the side pit 2. Therefore, it is almost unnecessary to lift the excavation slab upward through the entrance / exit 51 of the gantry 5 and carry it out. For example, if a vessel, bucket, or the like is used to lift the excavated slab upward from the entrance / exit 51 of the gantry 5 and carry it out, the work efficiency is poor, and even temporarily, it goes up and down with the reinforcing bar assembly. Since it is a work, there is a safety problem, but when the excavated excavation is discharged to the lower horizontal pit 2 through the glory hole 12 and carried out from the horizontal pit 2 as in the present embodiment, such efficiency occurs. There are no aspects or safety issues.

Further, in a large-scale underground structure such as a deep foundation pile 10, the necessary reinforcing bars 6 are also large-scale, but in this embodiment, the reinforcing bars 6 are assembled and installed on the gantry 5 in parallel with excavation by the above method. By leaving it, it will lead to shortening the construction period at the time of construction.

Further, in the present embodiment, not a mere scaffold for work, but a pedestal 5 for suspending and lowering the reinforcing bar is suspended, and the pedestal 5 is suspended and installed by adding the reinforcing bar 6 on the pedestal 5 according to the progress of excavation. As a result, it becomes possible to suitably perform the parallel work of the installation of the reinforcing bar 6 and the excavation, and the installation work of the reinforcing bar 6 can also be performed on the ground surface.

Further, in the present embodiment, by installing the belt conveyor 22 for carrying out the excavation shavings in the horizontal pit 2, the excavation shavings can be suitably carried out in the horizontal pit 2. However, as described above, various means can be considered for carrying out the excavation scrap from the side pit 2, and the method is not limited to the belt conveyor 22.

The glory hole 12 can be easily formed by drilling the ground downward to the horizontal shaft 2 using a raise boring machine 3 or the like, and then excavating upward to expand the diameter of the drilled hole. Further, in the present embodiment, by inserting the steel pipe 121 into the glory hole 12 and protecting the hole wall of the glory hole 12 with the steel pipe 121, it is possible to prevent the hole wall from gradually collapsing when the excavation scrap is thrown in. When the hole wall is protected by spraying concrete, the hole wall may collapse due to the impact at the time of blasting of explosives or the like, but when the hole wall is protected by the steel pipe 121, there is no such concern. However, if the hole wall of the glory hole 12 is strong, the steel pipe 121 can be omitted.

Further, in the present embodiment, by adding the soundproofing performance to the gantry 5 by the soundproofing material 53, it is possible to reduce the construction noise due to rock drilling, blasting, etc. by the heavy machine 4 performed below the gantry 5.

Further, by providing the lighting device 54 on the gantry 5, it is possible to illuminate the dark place of the excavation hole 13 below, which assists the excavation work and enables nighttime construction and the like.

Further, since the gantry 5 is provided with an entrance / exit 51 for workers or materials / equipment to enter / exit, it is possible to deal with a failure of the heavy machine 4 and evacuate the worker at the time of blasting.

In addition, by providing the gantry 5 with a sprinkler 55 and a dust collector 56, it is possible to take measures against dust associated with excavation.

However, the present invention is not limited to this. For example, the configuration of the gantry 5 is not limited to that described above, and it is also possible to provide a reaction force device on the side surface of the gantry 5 and install a downward excavator on the lower surface of the gantry 5 for excavation. It is also possible to provide an elevating facility for workers to move between the gantry 5 and the bottom of the excavation hole 13.

Further, as shown in FIG. 10A, the horizontal pit 2 may be provided at a position lower than the formation range 11 of the deep foundation pile. In this case, after excavation or the like is performed by the same process as described above, FIG. As shown in 10 (b), the deep foundation pile 10a is formed by placing concrete 17 in the excavation hole 13, the side shaft 2, and the glory hole 12 between them. The heavy equipment 4 and the like used for excavation can be carried out upward from the entrance / exit 51 of the gantry 5 as described above.

Further, in the present embodiment, the gantry 5 is lowered stepwise according to the progress of excavation, but the present invention is not limited to this. For example, the lowering of the gantry 5 may be stopped in the middle of excavation, and the gantry 5 may be lowered to the bottom of the excavation hole 13 at once after the excavation is completed. In this case, the gantry 5 is suspended with a high safety factor until the descent of the gantry 5 is stopped. It is also possible to suspend the gantry 5 with a safety factor slightly lower than the factor.

Further, it is possible not to lower the gantry 5 during excavation, but to lower the gantry 5 all at once to the bottom of the excavation hole 13 after the excavation is completed. In any case, it suffices that the gantry 5 is in the plane position of the excavation hole 13 when the excavation is completed and is present on the gantry 5 in a state where the necessary reinforcing bars 6 have been assembled. Further, the method of installing the reinforcing bar 6 is not particularly limited, and for example, a method of unitizing the reinforcing bar cage and connecting the units is also possible.

Further, in the present embodiment, the glory hole 12 is formed by drilling the ground downward to the horizontal shaft 2 using a raise boring machine 3 or the like, and then excavating upward to expand the diameter of the drilled hole. , The method of forming the glory hole 12 is not limited to this. By excavating the ground downward from the ground surface, it is also possible to directly form the glory hole 12 without going through the above-mentioned drilling work. For excavating the ground, use a down-the-hole hammer that hits the bit with a hammer to excavate the ground with the bit, or a full-turn all-casing that excavates the ground inside the casing while rotating it all around. There is a possibility that the glory hole 12 can be formed in a short period of time depending on the construction conditions and the like.

Further, in the present embodiment, an example of constructing a deep foundation pile as an underground structure has been described, but the underground structure is not limited to the deep foundation pile, and may be, for example, a container structure such as a tank. Further, depending on the scale of the underground structure, in some cases, it is possible to install a precast block or the like as the structure of the underground structure on the gantry 5 by the same method as described above instead of the reinforcing bar 6.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art can come up with various modified or modified examples within the scope of the technical idea disclosed in the present application, and these also naturally belong to the technical scope of the present invention. Understood.

1: Mountain 2: Side pit 3: Raise boring machine 4: Heavy equipment 5: Frame 6: Reinforcing bar 10, 10a: Deep foundation pile 12: Glory hole 13: Drilling hole 14: Guide wall 15: Suspension device 16: Suspension material 17 : Concrete 21: Vibration feeder 22: Belt conveyor 51: Doorway 53: Soundproof material 54: Lighting device 55: Water sprinkler 56: Dust collector 121: Steel pipe

Claims (6)

It ’s a method of constructing underground structures.
The process of constructing a cloaca in the ground and a discharge hole for discharging excavated shavings extending upward from the cloaca, and
The process of excavating the ground in the range including the discharge hole, throwing the excavated scrap into the discharge hole, and carrying it out from the side shaft.
In the process of excavating the ground to a predetermined depth, a step of suspending a gantry at the plane position of the excavation hole and installing the structure of the underground structure on the gantry.
A step of excavating the ground to a predetermined depth and then lowering the gantry to set the structure in a predetermined position.
A method for constructing an underground structure, which is characterized by being provided with. The structure is a reinforcing bar and
The method for constructing an underground structure according to claim 1, wherein after setting the reinforcing bar, concrete is placed in the excavation hole and the reinforcing bar and the gantry are embedded in the concrete. The method for constructing an underground structure according to claim 2, wherein the underground structure is a deep foundation pile. The method for constructing an underground structure according to any one of claims 1 to 3, wherein the gantry is suspended according to the progress of excavation of the ground. The method for constructing an underground structure according to claim 4, wherein a new structure is installed on the structure after the gantry is suspended. The method for constructing an underground structure according to any one of claims 1 to 5, wherein a belt conveyor for carrying out excavated shavings is installed in the horizontal shaft.

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