JP6969901B2 - Co-fall suppression structure and caisson sinking method - Google Patents

Description

The present invention relates to subsidence method of co-down suppressing structure and caissons.

Conventionally, when a caisson is subsided in the ground, various co-fall prevention structures have been adopted in order to prevent the co-fall of the surrounding ground and neighboring structures.
For example, in Patent Document 1, a friction-cutting jig made of a steel plate is used, and by projecting outward from the cutting edge and sinking, a friction-cutting portion consisting of a narrow gap is formed on the outer periphery of the skeleton to form a friction-cutting portion with the ground. The configuration for reducing the frictional force of the above is disclosed.
In addition, steel sheet piles were installed around the caisson, and measures were taken to prevent the surrounding ground from being affected when the caisson was subsided.

Japanese Unexamined Patent Publication No. 2016-138409

However, although it is possible to reduce the impact on the surrounding ground and nearby structures by providing a friction cut part consisting of narrow gaps and installing a steel sheet pile as an earth retaining material as in the past, measures are not sufficient. There is no request for further improvement.

Therefore, the present invention has been made in view of the above circumstances, and provides a co-fall suppression structure capable of more effectively suppressing co-fall of surrounding ground and neighboring structures and a caisson subsidence method. The purpose.

To achieve the above object, the co-down suppressing structure of the present invention comprises a caisson precursor to sink into the ground while forming the side wall portion by laminating annular body on a foundation base, soil disposed around the caisson skeleton The fastener, the ground improvement body supplied into the ground around the caisson skeleton and integrating the earth retaining material and the ground, and the ground improvement body installed on the top of the caisson skeleton can raise the earth retaining material. It is characterized by having a hanging part that supports it.

In the co-lowering suppression structure of the present invention, the ground improvement body is arranged in the ground around the caisson skeleton, and the retaining material is supported so as to be able to rise by the hanging portion. Therefore, when the caisson skeleton is subsided, an upward force can be applied to the ground around the caisson skeleton by raising the earth retaining material installed in the ground-improved area. As a result, it is possible to prevent the caisson skeleton from collapsing even if a downward peripheral frictional force acts on the ground around the caisson skeleton as the caisson skeleton sinks.
Therefore, when the caisson skeleton is subsided in the ground, it is possible to provide a co-fall suppression structure capable of more effectively suppressing the co-fall of the surrounding ground and neighboring structures.

In the co-lowering suppression structure according to the present invention, the hanging portion has a jack provided at the top of the caisson skeleton and a connecting material for connecting the jack and the earth retaining material. It is a feature.

According to this configuration, in the hanging portion, the earth retaining material is connected to the jack provided at the top of the caisson skeleton by a connecting material. That is, by providing a portion for supporting the earth retaining material in the caisson skeleton, it is not necessary to provide equipment for supporting the earth retaining material in the ground or structure near the caisson skeleton. Therefore, it is possible to easily construct the co-lowering suppression structure without increasing the working area.

Further, in order to achieve the above object, the caisson subsidence method of the present invention includes a caisson construction step of laminating an annular body on the bottom of the foundation to form a side wall portion and constructing a caisson skeleton, and a caisson skeleton around the caisson skeleton. The ground improvement material supply step of supplying the ground improvement material into the ground, the earth retaining material installation step of installing the earth retaining material in the ground improvement body formed by supplying the ground improvement material, and the above-mentioned below the caisson skeleton. The caisson subsidence step of excavating the ground and submerging the caisson skeleton is provided, and the earth retaining material supporting step of suspending and supporting the earth retaining material from above, and the soil at the time of or before and after the subsidence of the caisson skeleton. It is characterized by further being equipped with an earth retaining material lifting process for lifting the fastener.

In the caisson subsidence method of the present invention, in order to raise the earth retaining material at the time of or before and after the caisson skeleton sinks, an upward force is applied to the ground around the caisson skeleton to which a downward force is applied due to the subsidence of the caisson skeleton. can. Therefore, with the subsidence of the caisson skeleton, even if a downward peripheral frictional force acts on the ground around the caisson skeleton, it is possible to prevent the surrounding ground from descending together.
Therefore, when the caisson skeleton is subsided in the ground, it is possible to provide a method for subsidence of the caisson that can suppress the co-decay of the surrounding ground and the neighboring structures.

The method for submerging a cason according to the present invention is characterized in that, in the earth retaining material support step, a jack is arranged on the top of the cason skeleton, and the earth retaining material is suspended and supported by the jack.

According to this configuration, the earth retaining material suspended from the top of the Kason skeleton can be pulled up via a jack, so it is necessary to provide equipment to support the earth retaining material on the ground or structure near the Kason skeleton. No. That is, the construction can be carried out without increasing the working area.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a co-fall suppression structure and a caisson subsidence method capable of more effectively suppressing co-fall of surrounding ground and neighboring structures.

It is a schematic vertical sectional view of the co-dropping suppression structure which concerns on embodiment of this invention.

Hereinafter, the co-lowering suppression structure in the pneumatic caisson method according to the embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the pneumatic caisson 10 constructed in the present embodiment has a foundation bottom portion 15 provided at the lower end and a side wall portion 12 provided on the foundation bottom portion 15.

The foundation bottom portion 15 has a blade edge 13 provided downward at the lower end and a horizontal slab 14 provided at the upper end of the blade edge 13 to partition the work chamber 16. The outer shape of the cutting edge 13 in the horizontal direction and the outer shape of the slab 14 in the horizontal direction are formed substantially the same. In the foundation bottom 15, the blade edge 13 and the slab 14 are integrally constructed.
The side wall portion 12 is constructed by vertically stacking a plurality of annular bodies 11 on the bottom portion 15 of the foundation and connecting them vertically. The plurality of annular bodies 11 are formed to have substantially the same outer shape and inner shape.

The co-lowering suppression structure of the present embodiment is in the caisson skeleton 17 made of the pneumatic caisson 10 as described above, which forms the side wall portion 12 by the annular body 11 and sinks into the ground G, and in the ground G around the caisson skeleton 17. Supports the ground improvement material 18 supplied to, the steel sheet pile (earth retaining material) 19 installed in the ground improvement area (ground improvement body 25) to which the ground improvement material 18 is supplied, and the steel sheet pile 19 so as to be able to rise. The hanging portion 20 is provided.

The ground improvement material 18 may be any generally used ground improvement material, and may be, for example, a cement-based ground improvement material, a lime-based ground improvement material, a polymer-based ground improvement material, or a ground improvement material containing them. Just do it. The ground improvement material 18 is supplied to a place where the steel sheet pile 19 is installed, and the steel sheet pile 19 and the surrounding ground G are integrated by the ground improvement material 18 (ground improvement body 25).

The steel sheet pile 19 can be placed, for example, by driving into the ground G along the outer periphery of the side wall portion 12 and the foundation bottom portion 15, that is, the outer periphery of the caisson skeleton 17, and faces the entire circumference of the caisson skeleton 17 in the circumferential direction. It is arranged like this. Further, the steel sheet pile 19 is installed until it reaches a predetermined depth from the ground surface. For example, the steel sheet pile 19 is installed over the total length in the vertical direction of the portion arranged in the ground G in the caisson skeleton 17.
The steel sheet piles 19 and 19 adjacent to the top and bottom and the steel sheet piles 19 and 19 adjacent to the left and right are firmly connected by welding or the like, respectively.

The hanging portion 20 includes a pedestal 21 installed on the top 17a of the caisson skeleton 17, a jack 22 mounted on the pedestal 21, and a connecting member 23 made of a wire or the like connecting the jack 22 and the steel sheet pile 19. I have. The jack 22 may have a structure that pulls up the connecting member 23.
When the new annular body 11 is laminated on the side wall portion 12 of the caisson skeleton 17, the gantry 21 and the jack 22 are once removed from the top portion 17a of the caisson skeleton 17, and after the annular body 11 is laminated, the new top portion 17a of the caisson skeleton 17 is laminated. It is configured to be attached to.

Next, a method of sinking the pneumatic caisson 10 at the time of construction of the pneumatic caisson method will be described using such a co-fall suppression structure.
In the pneumatic caisson method, the foundation bottom 15 having the cutting edge 13 and the slab 14 is installed on the ground G, and the above-mentioned annular bodies 11 prepared in advance on the ground are sequentially laminated coaxially to form the side wall portion 12. By doing so, the caisson skeleton 17 is constructed (caisson construction process).

A region formed by supplying the ground improvement material 18 to a predetermined area of the ground G around the place where the pneumatic caisson 10 is installed (ground improvement material supply process) and then supplying the ground improvement material 18 (ground improvement body). A steel sheet pile 19 is installed in 25) (earth retaining material installation process). After the steel sheet pile 19 is installed, the pneumatic caisson 10 (caisson skeleton 17) is subsided to the ground G (caisson subsidence step).

After arranging the steel sheet pile 19 and the caisson skeleton 17, a hanging portion 20 (frame 21 and jack 22) is installed on the top 17a of the caisson skeleton 17. By connecting the steel sheet pile 19 and the jack 22 with the connecting material 23, the steel sheet pile 19 is suspended and supported via the jack 22 (earth retaining material support step).

By excavating the ground G below the caisson skeleton 17 in the work room 16, the caisson skeleton 17 is sequentially subsided. The pneumatic caisson 10 is constructed by sequentially laminating the annular body 11 on the side wall portion 12 with the subsidence of the caisson skeleton 17.

With the hanging portion 20 attached to the caisson skeleton 17, the steel sheet pile 19 is lifted by the jack 22 and raised in the ground G at the time of subsidence or before and after the caisson skeleton 17 is sequentially subsided (earth retaining material lifting process). .. As a result, an upward frictional force can be applied to the ground G.
The steel sheet pile 19 does not need to be raised every time the caisson skeleton 17 sinks. 19 may be raised.

By continuing such work and sequentially sinking the caisson skeleton 17 to construct the pneumatic caisson 10 to a desired size (depth), a target underground structure can be constructed.

According to the co-lowering suppression structure and the subsidence method of the pneumatic caisson 10 of the present embodiment, the steel sheet pile 19 is arranged in the ground G around the caisson skeleton 17, and the steel sheet pile 19 is supported by the hanging portion 20 so as to be able to rise. Has been done. Therefore, when the caisson skeleton 17 is subsided, the steel sheet pile 19 installed in the area improved by the ground improvement material 18 (ground improvement body 25) is raised to give an upward force to the ground G around the caisson skeleton 17. can. As a result, it is possible to prevent the caisson skeleton 17 from falling together even if a downward peripheral frictional force acts on the ground G around the caisson skeleton 17 as the caisson skeleton 17 sinks. Therefore, when the caisson skeleton 17 is subsided in the ground G, it is possible to more effectively suppress the co-lowering of the surrounding ground and the neighboring structures.

Further, in the hanging portion 20, the steel sheet pile 19 is connected to the jack 22 provided on the top portion 17a of the caisson skeleton 17 by the connecting member 23. That is, by providing the portion for supporting the steel sheet pile 19 in the caisson skeleton 17, it is not necessary to separately provide a facility for supporting the steel sheet pile 19 in the region near the caisson skeleton 17. Therefore, it is possible to easily construct the co-lowering suppression structure without increasing the working area.

Further, by pulling up the steel sheet pile 19 suspended from the top 17a of the caisson skeleton 17 via the jack 22, a downward force acts on the ground near the peripheral surface of the caisson skeleton 17 when the caisson skeleton 17 is subsided. Even so, the influence of the downward force on the surrounding ground G can be suppressed more effectively. Therefore, it is possible to more reliably prevent the surrounding ground and neighboring structures from falling together.

Although one embodiment of the co-drop prevention structure and the method of sinking the pneumatic caisson according to the present invention has been described above, the present invention is not limited to the above-described embodiment and is appropriately modified without departing from the spirit of the present invention. It is possible.
For example, in the above embodiment, the example of the pneumatic caisson 10 having a substantially circular shape in a plan view has been described, but the shape of the pneumatic caisson 10 is not particularly limited, and may be, for example, a polygonal shape in a plan view.
Further, in the above embodiment, the case of the pneumatic caisson 10 and its construction method has been described, but a construction method other than the pneumatic caisson construction method may be used.
Further, in the above embodiment, the case where the steel sheet pile 19 is adopted as the earth retaining material has been described, but the earth retaining material other than the steel sheet pile 19 may be adopted.

10 Pneumatic caisson 11 annular body 12 side wall 13 blade edge 14 slab 15 foundation bottom 17 caisson skeleton 18 ground improvement material 19 steel sheet pile (earth retaining material)
20 Suspended part 21 Stand 22 Jack 23 Connecting material 25 Ground improvement body G Ground

Claims (4)

A caisson skeleton that subsides to the ground while forming a side wall by stacking annular bodies on the bottom of the foundation.
The earth retaining material arranged around the caisson skeleton and
A ground improvement body that is supplied into the ground around the caisson skeleton and integrates the earth retaining material and the ground.
A hanging part installed on the top of the caisson skeleton and supporting the earth retaining material so as to be able to rise.
A co-lowering suppression structure characterized by being equipped with. The joint according to claim 1, wherein the hanging portion has a jack provided at the top of the caisson skeleton and a connecting member for connecting the jack and the earth retaining material. Fall suppression structure. A caisson construction process in which an annular body is laminated on the bottom of the foundation to form a side wall to construct a caisson skeleton.
The ground improvement material supply process for supplying the ground improvement material into the ground around the caisson frame, and the ground improvement material supply process.
The earth retaining material installation process of installing the earth retaining material in the ground improvement body formed by supplying the ground improvement material, and
A caisson subsidence step of excavating the ground below the caisson skeleton to subside the caisson skeleton is provided.
The earth retaining material support process of suspending and supporting the earth retaining material from above, and
A method for subsidence of a caisson, further comprising a step of lifting the earth retaining material at the time of or before and after the subsidence of the caisson skeleton. The method for sinking a pneumatic caisson according to claim 3, wherein in the earth retaining material support step, a jack is arranged on the top of the caisson skeleton, and the earth retaining material is suspended and supported by the jack.

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