JP6402056B2 - Vertical shaft, underground storage tank, vertical shaft construction method and underground storage tank construction method - Google Patents

Description

  The present invention relates to a vertical shaft having an embankment portion around the outside of the ground, an underground storage tank, a vertical shaft construction method, and an underground storage tank construction method.

When embankment is performed around a vertical shaft, if the excavation residual soil generated by excavation of the vertical shaft is used as the embankment material, labor and cost required for carrying out the excavation residual soil can be reduced.
For example, in an LNG underground tank (underground storage tank) or the like, a banking part may be formed by building up excavation residual soil on the outer peripheral part of the chassis after the construction of the chassis.
The remaining excavated soil at the time of shaft construction needs to be stored in a temporary storage area from the time the shaft is excavated until the construction of the frame is completed. There are cases where it cannot be secured.

  In Patent Document 1, as an underground tank construction method that does not require a temporary storage site for excavated soil, a cylindrical underground wall 101 is constructed in the ground as shown in FIG. The side wall upper part 102 is constructed so as to protrude upward from the inside of the wall, the ground surrounded by the underground continuous wall 101 is excavated, and after excavating the remaining excavated soil 103 around the side wall upper part 102, the underground continuous wall 101 A method is disclosed in which a sidewall lower portion 104 is constructed along the inner surface and integrated with the sidewall upper portion 102.

JP 2012-036661 A

The construction method of the underground tank of Patent Document 1 takes time to install and remove the formwork and support members for constructing the upper side wall 102.
In addition to the vertical load (shearing force), a tensile force acts on the joint between the side wall upper part 102 and the underground continuous wall 101 due to the embankment earth pressure. It is necessary to increase the bonding strength. That is, the construction of the upper part of the underground continuous wall 101 (joint part between the sidewall upper part 102 and the underground continuous wall 101) is complicated.
Moreover, since the side wall upper part 102 is deformed by the embankment earth pressure, a process for suppressing the deformation amount of the side wall upper part 102 may be required.
Further, since the side wall upper portion 102 is used as a retaining wall (temporary member) at the time of forming the embankment portion, residual stress may be generated even after the side wall lower portion 104 is constructed (after the side wall is completed). Therefore, it becomes difficult to manage the stress state of the sidewall upper part 102.
Moreover, since the side wall upper part 102 is formed along the inside of the underground continuous wall 101, the inside of the underground continuous wall 101 cannot be excavated during the construction of the side wall upper part 102.
In addition, by constructing the sidewall upper portion 102 having a predetermined height, the field of view is blocked from an early stage, making it difficult to check the situation inside the shaft.

  From this point of view, the present invention provides a shaft, an underground storage tank, a shaft construction method, and a method for constructing an underground storage tank that can be easily constructed even when there is a banking portion around the outside of the ground. It is an issue to propose.

In order to solve the above-mentioned problems, the shaft according to the present invention includes an underground continuous wall formed in a cylindrical shape, a segment ring erected on an upper end of the underground continuous wall, and raised around an outer periphery of the segment ring. And the embankment portion is formed of a embankment material including excavation residual soil generated by excavating the ground surrounded by the underground continuous wall.
It is desirable that a reinforcing material is embedded in the embankment.

  The shaft construction method of the present invention includes a step of forming an underground continuous wall in a cylindrical shape, a step of forming a segment ring by assembling a plurality of segments at an upper end of the underground continuous wall, and the underground A step of excavating the ground surrounded by the continuous wall and raising the embankment material including the excavated residual soil generated by the excavation of the ground around the outer periphery of the underground continuous wall.

According to the shaft and the method for constructing the shaft, since the segment which is a precast member is used, the workability is excellent.
Moreover, if construction is performed according to the rising of the embankment, it is possible to omit or reduce the scaffold when assembling the segments. Moreover, it can prevent that a visual field is obstruct | occluded by a segment ring by constructing a segment ring in steps.
Further, since the segment ring is formed at the upper end of the underground continuous wall, the segment ring can be constructed and excavated in parallel without interfering with the excavation inside the underground continuous wall.

  Further, the underground storage tank of the present invention is a continuous underground wall formed in a cylindrical shape, a segment ring erected at the upper end of the underground continuous wall, and a banking portion raised around the outer periphery of the segment ring And a concrete side wall formed along the inner surface of the underground continuous wall and the segment ring, and the embankment portion is generated by excavating the ground surrounded by the underground continuous wall It is formed by the embankment material containing excavation residual soil, The upper part of the said side wall is formed using the said segment ring as an outer mold frame, It is characterized by the above-mentioned.

  The underground storage tank construction method of the present invention includes a step of forming an underground continuous wall in a cylindrical shape, a step of forming a segment ring by assembling a plurality of segments at the upper end of the underground continuous wall, A step of excavating the ground surrounded by the underground continuous wall and embedding a filling material including excavated residual soil generated by the excavation of the ground around the outer periphery of the underground continuous wall; the underground continuous wall and the segment ring; And a step of forming a side wall along the inner surface.

According to the underground storage tank and the construction method of the underground storage tank, the work of installing the outer mold on the side wall can be omitted, and therefore, the workability is excellent.
Moreover, if the embankment is constructed in stages, earth pressure management is easy, and earth pressure and uneven earth pressure acting on the side wall can be eliminated.
Since the side wall is constructed after the embankment is constructed, no residual stress is generated on the side wall, and the amount of deformation generated on the side wall due to earth pressure can be suppressed.

  According to the vertical shaft, underground storage tank, vertical shaft construction method, and underground storage tank construction method of the present invention, it is possible to easily construct even if there is a banking portion outside the above-ground part.

(A) Sectional drawing which shows the underground type storage tank which concerns on embodiment of this invention, (b) is the same top view. It is a figure which shows the initial excavation state after underground continuous wall construction in the construction method of an underground type storage tank, Comprising: (a) is sectional drawing, (b) is a top view. (A) And (b) is a schematic diagram which shows the structure of the junction part of a segment ring and an underground continuous wall. It is an expanded sectional view which shows a part of embankment part. It is a figure which shows the construction condition following FIG. 2, (a) is sectional drawing, (b) is a top view. (A) is sectional drawing which shows the construction condition following FIG. 5, (b) is sectional drawing which shows the construction condition following (a). It is a schematic diagram which shows an example of the junction part of segments. It is sectional drawing which shows the construction method of the conventional underground storage tank.

  As shown in FIGS. 1A and 1B, an underground storage tank 1 according to an embodiment of the present invention includes a bottom plate 2, a side wall 3 standing on the bottom plate 2, and a top portion of a space surrounded by the side wall 3. The roof 4 is shielded, the shaft 5 is formed around the side wall 3, and the membrane 10 is attached to the bottom plate 2 and the inner surface of the side wall 3.

The bottom plate 2 is a concrete structure formed so as to cover the lower surface of the membrane 10 as shown in FIG. A bottom heater (not shown) is embedded in the bottom plate 2 as necessary.
A drainage layer (not shown) is formed below the bottom plate 2 as necessary. Although the structure of a drainage layer is not limited, For example, what is necessary is just to form by spreading a crushed stone etc.

  The side wall 3 is a concrete structure erected on the peripheral edge of the bottom slab 2. The side wall 3 of the present embodiment has a circular shape (cylindrical shape) in plan view as shown in FIG. Moreover, what is necessary is just to set the wall thickness and wall height of the side wall 3 suitably.

As shown in FIG. 1A, the roof 4 is formed at the upper end of the side wall 3 and covers the upper surface of the membrane 10.
The peripheral edge of the roof 4 is fixed to the upper end of the side wall 3.
In this embodiment, the roof 4 is formed of a steel member, but the roof 4 may be formed of, for example, a concrete member.

The vertical shaft 5 includes a continuous underground wall 6, a ground wall 71 formed by a segment ring 7, and a banking portion 8.
As shown in FIGS. 1A and 1B, the continuous underground wall 6 is formed in a cylindrical shape so as to surround the outer periphery of the side wall 3.
The lower end of the continuous underground wall 6 reaches the poorly permeable layer below the bottom plate 2. The height of the continuous underground wall 6 and the position in the depth direction are not limited. The wall thickness of the continuous underground wall 6 is not limited and may be set as appropriate, but in the present embodiment, the wall thickness is in the range of 1 to 1.5 m.
Further, a side heater (not shown) is disposed on the continuous underground wall 6 as necessary. The configuration of the side heater is not limited.

As shown in FIG. 1A, the ground wall 71 is formed by laminating a plurality of stages of segment rings 7, 7, 7 on the continuous underground wall 6. In the present embodiment, three segment rings 7 are laminated, but the number of segment rings 7 is not limited, and depends on the design height of the embankment portion 8 and the height per segment ring 7 or the like. May be set as appropriate.
As shown in FIG. 1B, the segment ring 7 is formed in a cylindrical shape by arranging a plurality of precast segments in the circumferential direction of the continuous underground wall 6, and is formed at the upper end of the underground continuous wall 6. It is erected. In addition, the segments adjacent to each other on the left and right or the top and bottom are joined with a bolt or the like. In this embodiment, a concrete precast member is used as a segment, but the material constituting the segment is not limited, and for example, a steel segment, a synthetic segment, a high strength fiber reinforced concrete segment, or the like is used. May be.

  The inner surface of the segment ring 7 of the present embodiment may be flush with the inner surface of the continuous underground wall 6 or may have a step between the inner surface of the segment ring 7 and the inner surface of the continuous underground wall 6. In addition, the dimensions such as the height and the member thickness of each segment are not limited and may be set as appropriate. In the present embodiment, the height is in the range of 1.5 to 15.0 m and the width is 1. The thickness is in the range of 5 to 15.0 m and the thickness is in the range of 5 to 150 cm. Further, if a segment L-shaped segment that can stand alone is used as the lowermost segment ring 7, a temporary support member or the like when assembling the segment ring 7 may be omitted.

As shown in FIGS. 1 (a) and 1 (b), the embankment portion 8 is excavated residual soil (embankment material) generated by excavating the ground surrounded by the underground continuous wall 6 around the outer periphery of the ground wall 71. It is formed by raising. Note that the embankment portion 8 is not necessarily formed only from excavated residual soil (diverted soil), and may include materials carried from the outside (such as generated soil and purchased soil).
The upper surface of the embankment portion 8 is raised until it reaches a height equivalent to the upper end of the ground wall 71. Further, a slope with a stable gradient is formed on the outer periphery (outer edge) of the embankment portion 8, and is rubbed to the height of the original ground (ground surface GL). In addition, the outer periphery of the embankment part 8 does not necessarily need to have a slope with a stable gradient. For example, a gradient around the embankment portion 8 may be established by employing a reinforcement method or a retaining wall. As the reinforcing method, for example, the embankment portion may be formed by improved soil obtained by mixing cement with embankment material.

Next, the construction method of the underground storage tank 1 will be described.
The underground storage tank 1 is constructed by an underground wall construction process, a ground wall formation process, a banking process, and a tank construction process.

The underground wall construction process is a process of constructing the continuous underground wall 6.
The continuous underground wall 6 is formed with a cylindrical groove (circular in plan view) so as to surround the area where the underground storage tank 1 is to be formed. (See FIGS. 2A and 2B). The continuous underground wall 6 is formed so as to reach the hardly permeable layer. Concrete is cast from the bottom of the groove using a tremy tube (not shown). Moreover, in this embodiment, after placing concrete, the upper part is removed (latency removal) and the concrete is newly placed to form the upper part of the continuous underground wall 6 (coping concrete 61) (see FIG. 3). ).
In addition, the structure of the continuous underground wall 6 is not limited, For example, it may replace with a reinforcing bar rod and may install core materials, such as a shape steel material. Moreover, you may employ | adopt a stable liquid solidification continuous wall method and a soil cement continuous wall method. Moreover, what is necessary is just to form the coping concrete 61 as needed.

When the continuous underground wall 6 is constructed, the shaft 5 is formed by carrying out the ground wall forming process and the embankment process in parallel.
That is, until the embankment portion 8 having a predetermined height is formed, the segment ring 7 is constructed and the excavation remaining soil around the outer periphery of the segment ring 7 is implemented.
First, after construction of the continuous underground wall 6, as shown in FIGS. 2A and 2B, initial excavation is performed (filling step). The initial excavation may be performed in parallel with the construction work of the lowermost segment ring 7.

  The initial excavation is performed using the excavator M1 such as a backhoe on the ground surrounded by the continuous underground wall 6. The excavated residual soil generated by excavation is carried out to the outside of the continuous underground wall 6 using a transport vehicle M2 such as a truck, and piled up around the outer periphery of the continuous underground wall 6. Note that the banking is performed at a position away from the segment ring 7 until the segment ring 7 is completely circular (closed). At this time, in the space surrounded by the continuous underground wall 6, the spiral temporary road 11 extending from the bottom of the excavation to the ground surface around the outer surface of the continuous underground wall 6 is caused by the longitudinal gradient that the transport vehicle M2 can travel. Is formed.

As shown in FIG. 2B, the lowermost segment ring 7 is formed by assembling a plurality of segments 72 at the upper end of the underground continuous wall 6 (ground wall forming step).
The lowermost segment ring 7 is erected on the upper surface of the underground continuous wall 6. The method for fixing the segment ring 7 to the underground continuous wall 6 is not limited. For example, a part of the segment ring 7 may be embedded in the top portion (coping concrete 61) of the underground continuous wall 6 (see FIG. 3A), or a predetermined jig 74 (for example, an angle material and an anchor) is used. And you may fix to the upper end of the underground continuous wall 6 (refer FIG.3 (b)). Further, the segment ring 7 may be fixed to the underground continuous wall 6 by rigid bonding, pin bonding, or the like.
Assembling of the lowermost segment ring 7 is performed in a state where the segment is supported by a supporting member (cheek cane material, diagonal material, etc.) as necessary so that the segment does not fall down.
In addition, as shown in FIG. 4, a drainage pipe 73 for draining water that has penetrated into the embankment 8 into the shaft 5 is provided in the lowermost segment ring 7 as needed.

When the lowermost segment ring 7 is completed, as shown in FIGS. 5A and 5B, the ground surrounded by the underground continuous wall 6 is excavated, and the excavated residual soil generated by the excavation of the ground is segmented. Raise the outer circumference of 7 (filling process).
In the present embodiment, in the space surrounded by the underground continuous wall 6, the ground is excavated by using the excavating machine M <b> 1, and the excavated residual soil is disposed on the ground portion outside the underground continuous wall 6. It is carried out to the ground part using the lifting machine M3. At this time, in the shaft (in the space surrounded by the underground continuous wall 6), the excavation residual soil excavated by the excavating machine M1 using the transport vehicle M2 is transported below the lifting machine M3. In addition, you may perform the conveyance of the excavation residual soil in a shaft by other transport means, such as a belt conveyor.

The excavated residual soil transported to the ground is transported to a predetermined position on the outer periphery of the segment ring 7 by the transport vehicle M2, and then leveled by a leveling machine M4 such as a bulldozer, and if necessary, a rolling roller Compressed by etc. In addition, the excavated residual soil may be spread directly after being conveyed, or may be spread after temporarily placing. Moreover, you may level the improvement soil which mixed solidification materials, such as cement, with excavation residual soil.
As shown in FIG. 5 (b), the construction of the embankment portion 8 is to be spirally raised along the circumferential direction of the segment ring 7 with a longitudinal gradient that allows the transport vehicle M3 to travel. The upper surface of the embankment part 8 is configured to be usable as a temporary road 11.
Moreover, the embankment part 8 of this embodiment is a self-supporting embankment. As shown in FIG. 4, reinforcing materials (so-called geotextiles) 81, 81,... Are laid on the inner peripheral portion of the embankment portion 8 at predetermined heights.
In addition, the construction of the embankment part 8 does not necessarily need to be heaped up spirally. Further, the reinforcing material may be laid as necessary.

In addition, it is desirable to minimize earth pressure acting on the segment ring 7 by installing a protective material 82 such as a gabion or a sandbag at the end of the banking portion 8 on the segment ring 7 side. The protective material 82 may be omitted, and a slope may be formed on the embankment portion 8, or the embankment portion 8 (excavated residual soil) may be formed in contact with the outer peripheral surface of the segment ring 7.
Filler 9 is filled in the gap between the protective material 82 and the segment ring 7. As the filler 9, it is desirable to use a drainage material such as sand or gravel, but excavated residual soil or purchased soil may be used. The filling of the filler 9 is preferably performed after the embankment 8 is rolled. In this way, since a gap is formed between the segment ring 7 and the embankment 8 during rolling, the pressure during rolling does not act on the segment ring 7, and the segment ring 7 (segment ).

When the embankment 8 is constructed to a predetermined height (in the present embodiment, near the middle of the lowermost segment ring 7), the second stage segment ring 7 is assembled as shown in FIG. Process). The second stage segment ring 7 is joined to the upper surface of the lowermost segment ring 7.
The segment constituting the segment ring 7 is transported to a predetermined position (assembly position) by a vehicle using a temporary road 11 formed on the embankment portion 8. In addition, the conveyance method of a segment is not limited.

When the second stage segment ring 7 is formed, as shown in FIG. 6A, the ground surrounded by the underground continuous wall 6 is excavated, and the remaining excavated soil generated by the excavation of the ground is second segmented. Raise the outer circumference of the ring 7 (filling process).
Similarly, by repeating the ground wall forming step and the embankment step, the ground wall 71 and the embankment portion 8 having a predetermined height are formed while excavating to the flooring surface.

It is desirable that the assembly operation of the segment ring 7 and the embedding operation of the embankment portion 8 are performed in parallel at different positions.
That is, for example, when the lifting machines M3 are arranged at positions facing each other across the center of the shaft 5, and the embankment portion 8 is constructed in the vicinity thereof (see FIG. 5B), from the lifting machine M3 The segment ring 7 may be assembled at a position that is sufficiently distant and raised to a predetermined height.

The tank construction process is a process of constructing the bottom plate 2, the side wall 3 and the roof 4 inside the shaft 5.
First, crushed stone or the like is spread on the flooring surface 51 (see FIG. 6B) of the shaft 5 to form a drainage layer (not shown).
Next, the bottom plate 2 is formed (see FIG. 1). At this time, a bottom heater (not shown) is embedded as necessary.

Then, the side wall 3 is formed along the inner surface of the continuous underground wall 6 and the ground wall 71 (refer FIG. 1).
The construction of the side wall 3 uses the segment ring 7 as an outer mold. That is, an inner mold frame (not shown) is provided inside the continuous underground wall 6 and the ground wall 71 with a gap ensuring the wall thickness of the side wall 3, and concrete is placed in the gap to form the side wall 3. Form.

If the side wall 3 is formed, the roof 4 is formed and the upper surface of the side wall 3 is shielded (see FIG. 1).
First, the roof 4 is assembled on the bottom plate 2 in a space surrounded by the side walls 3. Next, by raising the internal atmospheric pressure, the roof 4 is lifted and fixed to the upper end of the side wall 3. In addition, the construction method (lifting method) of the roof 4 is not limited, For example, a support work may be utilized and a jack may be utilized.
In addition, the membrane 10 is attached to the inner surface of the bottom plate 2 and the side wall 3 with the construction of the roof 4. The membrane 10 is attached to the bottom plate 2 and the side wall 3 through a cold insulating material (not shown).

According to the construction method of the underground type storage tank 1 (vertical shaft 5) and the underground type storage tank (vertical shaft) of the present embodiment, the ground wall 71 is formed using the segment which is a precast member. Excellent workability compared to wall bodies.
Moreover, the construction period can be shortened by performing the construction of the segment ring 7 and the construction of the embankment portion 8 in parallel.

In addition, by forming the second and subsequent segment rings 7 after forming the embankment portion 8 to a certain height, it becomes possible to omit or reduce the scaffold when assembling the segments.
Moreover, earth pressure management is easy by constructing the embankment part 8 in steps, and the earth pressure, uneven earth pressure, and water pressure which act on the side wall 3 can be excluded. Moreover, the earth pressure and water pressure which act on the side wall 3 are suppressed to the minimum by laying the reinforcing material 81 in the banking part 8, and making the banking part 8 self-supporting.

Since the excavated residual soil is used for the embankment 8, the amount of soil discharged can be greatly reduced, which is economical. In addition, since the yard for temporarily placing the excavated soil can be omitted or reduced, construction is possible even when the usable site is limited. Furthermore, since the transport distance of excavated soil can be significantly reduced, it is efficient.
Since the construction of the embankment portion 8 is performed outside the segment ring 7, it is possible to prevent the embankment material and the like from falling into the shaft 5 during construction of the embankment portion 8.

Since the embankment portion 8 functions as a counterweight, the underground storage tank 1 is prevented from rising.
Moreover, since the settlement of the ground around the shaft 5 can be promoted by the embankment portion 8 from the time of construction, the amount of consolidation settlement after the completion of the shaft 5 can be suppressed. Therefore, it is possible to accelerate the start of incidental work.
Since the underground continuous wall 6 and the segment ring 7 are formed in a circular shape (cylindrical shape), they exhibit sufficient strength against earth pressure and groundwater pressure.

Further, since the segment ring 7 is used for the outer mold of the side wall 3, the work of installing the outer mold can be omitted. Moreover, since a reaction force body such as a thick end material at the time of placing concrete can be omitted, it is possible to reduce labor and cost required for installing the reaction force body.
Since the drain pipe 73 is piped to the ground wall 71, the water in the embankment part 8 can be drained and the burden on the side wall 3 can be reduced.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and the above-described components can be appropriately changed without departing from the spirit of the present invention.
In the above embodiment, the case of constructing an underground storage tank has been described, but the use of the shaft of the present invention is not limited. For example, it may be used as a shaft for earth retaining when constructing any underground structure such as a building or a station, or may be used as a starting or reaching shaft for tunnel construction.

Although the said embodiment demonstrated the case where a reinforcing material was laid in the embankment part, you may abbreviate | omit a reinforcing material. Further, the reinforcing material may be disposed only at the lower part of the embankment part, or may be disposed at the entire height.
Moreover, the excavation method in the shaft (the inside of the underground continuous wall), the sediment transport method, and the like are not limited to the methods shown in the embodiment.
In the initial excavation, if only the central part is excavated with the original ground left in an annular shape along the inner surface of the underground continuous wall, the scaffold for forming the lowest segment ring can be placed inside and outside the segment ring. Can be secured.
As shown in FIG. 7, in the segment ring 7, a reinforcing member 75 that covers the joint portion may be fixed to the outside of the joint portion between the segments 72. By carrying out like this, the proof stress with respect to the ring compression of the segment ring 7 can be raised more.

DESCRIPTION OF SYMBOLS 1 Underground storage tank 10 Membrane 2 Bottom plate 3 Side wall 4 Roof 5 Vertical shaft 6 Underground continuous wall 7 Segment ring 71 Ground wall 8 Embankment part

Claims (5)

A continuous underground wall formed in a cylindrical shape;
A segment ring erected at the upper end of the underground continuous wall;
A shaft provided with an embankment raised on the outer periphery of the segment ring,
The shaft is characterized in that the embankment portion is formed of an embankment material including excavation residual soil generated by excavating the ground surrounded by the underground continuous wall.   The shaft according to claim 1, wherein a reinforcing material is embedded in the embankment. A continuous underground wall formed in a cylindrical shape;
A segment ring erected at the upper end of the underground continuous wall;
An embankment raised on the outer periphery of the segment ring;
An underground storage tank comprising: the underground continuous wall and a side wall formed along the inner surface of the segment ring;
The embankment portion is formed of a fill material including excavation residue generated by excavating the ground surrounded by the underground continuous wall;
An underground storage tank, wherein an upper portion of the side wall is formed with the segment ring as an outer mold. Forming the underground continuous wall into a cylindrical shape;
Forming a segment ring by assembling a plurality of segments at the upper end of the underground continuous wall;
Excavating the ground surrounded by the underground continuous wall, and raising the embankment material including excavation residual soil generated by excavating the ground around the outer periphery of the underground continuous wall, How to build a shaft. Forming the underground continuous wall into a cylindrical shape;
Forming a segment ring by assembling a plurality of segments at the upper end of the underground continuous wall;
Excavating the ground surrounded by the underground continuous wall, and raising the embankment material including excavation residual soil generated by excavating the ground around the outer periphery of the underground continuous wall;
Forming a side wall along the underground continuous wall and the inner surface of the segment ring, and a method for constructing an underground storage tank.

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