JP2001107348A - Marine artificial ground and construction method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the large-scale artificial ground located on the weak ground mainly influenced by uneven settlement and constructed on the sea and a construction method therefor. SOLUTION: A working platform unit constituted in a scull shape out of a base slab laid on the sea bottom surface, plural inclined columns built in a height projecting on the sea so as to incline at least in orthogonal two directions on the base slab and a capital part block for firmly connecting the upper ends of the inclined columns on the sea is built on the sea bottom surface. The marine artificial ground is constituted of an assembly of plural working platform units, and foundation beams of an upper building and a structure are horizontally supported. A pedestal is placed on an upper surface of the capital part block via a shear key, and this pedestal is fastened to the foundation beams of the upper building and the structure directly or indirectly via a base isolation device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a large-scale artificial ground constructed on the sea, which is located on a soft ground mainly affected by differential settlement, and a construction method thereof.

[0002]

2. Description of the Related Art Conventionally, technologies for constructing a large-scale artificial ground at sea, such as an international airport, are based on a landfill construction, a floating structure in which a caisson or the like floats on the sea surface, or a gravity structure (Japanese Patent Publication No. 53-40822
JP-A-5-148830, a soft bottom structure (for example, refer to the invention described in JP-A-5-148830), and a pile pier (jacket) system (for example, JP-A-8-14883). 170346, JP-A-7-9
0830, JP-A-10-77615, JP-A-11-
Various methods are known and practiced.

[0003]

In the above-mentioned marine artificial ground by the conventional landfill construction, if the target submarine ground is a soft ground having a thick layer, an unpredictable landfill amount is required and the construction period is prolonged. , The cost becomes enormous. In addition, it adversely affects buildings and facilities located in adjacent existing landfills, such as deformation. Large-scale ground improvement is required to prevent or suppress such adverse effects.

[0004] The artificial marine ground having a floating structure in which the above-mentioned caisson and the like float on the sea surface is excellent in seismic isolation, depth of water depth, and adaptability to the structure of the seabed ground. However, although a crossing pier of a pin roller is usually built on the connection with the land, the usability against tide level fluctuation is poor, and the management and control thereof are complicated.

[0005] Artificial offshore ground with the above-mentioned gravity type structure (such as the invention described in Japanese Patent Publication No. 53-40822).
However, if landfill construction is extended on soft ground with a thick layer, buildings and facilities located in adjacent existing landfills will have adverse effects such as deformation, and large-scale grounds will be required to prevent or suppress such adverse effects. Improvement is needed. Also,
Since buoyancy acts on a structure, a ballast that resists buoyancy is required in a place where the water depth is deep, and this ballast receives an extremely large inertial force, and a vicious circle causing sinking occurs.

[0006] The marine artificial ground using the soft-bottomed structure (see, for example, the invention described in Japanese Patent Application Laid-Open No. 5-148830) is partially submerged in water, though not as much as the gravity type. Therefore, a change in the effective weight (air weight-buoyancy) due to a change in tide level causes a large land subsidence or requires mooring equipment. The structure has a large inertial force at the time of an earthquake of about level 2 and slides, making it difficult to restore and correct the position. In addition, as in the invention described in JP-A-5-148830, a water-blocking breakwater is disposed around the breakwater. In the case of such a configuration, there is a problem that construction of the breakwater is costly and that seawater exchange is necessary for water quality and environmental protection in the breakwater.

The artificial artificial ground based on the pile pier (jacket) method (JP-A-8-170346, JP-A-7-9)
0830, JP-A-10-77615, JP-A-11-
The invention described in Japanese Patent Application Laid-Open No. 117276/1995) is a supporting pile, and a huge construction cost is required for driving a steel pipe pile forming a “tilted pile” deeply into a support layer below the seabed ground. In addition, there is a problem that a disadvantageous complicated external force acts on the "tilt pile" due to horizontal displacement and uneven settlement from the periphery.

It is an object of the present invention to provide a marine artificial ground located on soft ground affected by differential settlement, and a “follow-up type” capable of timely and appropriate correction processing for generated differential settlement, In the state where consolidation settlement does not converge, it can be suitably implemented not only in the structure's own weight but also in places where there is a high possibility of vertical and horizontal deformation due to the load of the structure from the periphery, expansion and expansion It is an object of the present invention to provide a marine artificial ground which can be applied to places where settlement rates and degrees of deformation are different depending on the type of settlement, and are implemented on the assumption that uneven settlement occurs, and a construction method therefor.

[0009]

Means for Solving the Problems As means for solving the above-mentioned problems, an artificial marine ground according to the first aspect of the present invention comprises a base slab laid on a sea bottom, and a base slab on the base slab. A gantry unit composed of a plurality of inclined struts built at a height protruding to the sea by inclining in at least two orthogonal directions and a column head block strongly connecting the upper ends of the inclined struts at sea is a gantry unit configured in a tower shape. Built on a surface, the marine artificial ground is constituted by a collection of a plurality of gantry units, the foundation beams of the upper buildings and structures are horizontally supported, and the pedestal is a shear key on the upper surface of the capital block. And the base is directly or indirectly connected to a foundation beam of an upper building or a structure via a seismic isolation device or the like.

According to a second aspect of the present invention, in the marine artificial ground according to the first aspect, a horizontal displacement transmitted from the submarine ground is provided between a concave portion and a convex portion forming a shear key connecting the capital block and the pedestal. Is formed as a difference in diameter between the concave portion and the convex portion.

According to a third aspect of the present invention, in the marine artificial ground according to the first or second aspect, the capital block is provided with a space in which a required number of jacks for correcting settlement can be installed vertically with a foundation beam. It is characterized in that it has a size and a shape, and has a configuration in which an unequal settlement correction plate can be sandwiched between the pedestal and the capital block.

According to a construction method of an artificial offshore ground according to the invention described in claim 4, the soft undersea ground is improved by a deep mixing method, the sea bottom is leveled by abandoned stones, and the sea bottom is laid on the sea bottom. Base slab, and inclined in at least two directions perpendicular to the base slab,
Manufacture onshore a gantry unit composed of a plurality of inclined props built at the height protruding above the sea and a column head block that strongly connects the upper ends of the inclined props at sea,
Transporting by sea and submerging it at a predetermined position on the sea floor, placing the pedestal on the upper surface of the column cap block of each gantry unit via a shear key, directly on the pedestal of each gantry block Or indirectly constructing the foundation beams of upper buildings and structures indirectly through seismic isolation devices, etc., and tying them together.

According to a fifth aspect of the present invention, in the method of constructing an artificial offshore ground according to the fourth aspect, the adjustment of the height of the foundation beams of the upper building and the structure, or the correction for the uneven settlement of the undersea ground, The required number of uneven settlement correction jacks are installed vertically between the column cap block and the foundation beam, the foundation beam is raised by jacking up the jack, and the correction plate is inserted between the pedestal and the column cap block The feature is to secure the horizontality of the foundation beam.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 conceptually show a basic embodiment of a marine artificial ground according to the first to third aspects of the present invention. FIG. 3 shows an embodiment in which a multi-story building 2 is constructed on a foundation beam 1 (or floor slab).

In the marine artificial ground according to the present invention, the soft seabed ground 3 in the sea area to be located is first subjected to ground improvement by the deep mixing method,
The seabed of the improved ground 4 reinforced in this way is leveled by the waste stones 5 and built on it.

As shown in FIG. 3, the main supporting body of the artificial marine ground is a base slab 11 laid on the flat seabed as described above and the base slab 1.
1 at least in two orthogonal directions (FIG. 5). L. A gantry unit 10 configured in a tower shape (or a so-called truss structure) with a plurality of inclined props 12 built at a height protruding above the floor, and a column head block 13 that strongly connects the upper ends of the inclined props 12 at sea. It is.
The structural principle of the gantry unit 10 is the same as that of the above-described inclined support 1.
No. 2 described in JP-A-8-170346 and JP-A-7-170346 described above.
No. 90830, JP-A-10-77615, JP-A-11-775
The same function as the slant pile or the slant pile disclosed in -117276 is expected. However, the difference is that the inclined prop 12 of the present invention does not penetrate into the seabed ground, but is only erected on the base slab 11, and is not a support pile.

The gantry unit 10 having the above-described structure is installed with its base slab 11 settled on the sea bottom, and the base slab 11 is placed on the sea surface W.C. L. Up to the height that protrudes above. For example, as shown in FIG. 2, a set of a plurality of gantry units 10 arranged regularly and arranged to make a vertical x horizontal 200 × 40.
A foundation beam 1 of a 0 m scale upper building is horizontally supported. Therefore, also for uneven settlement of the seabed,
The gantry unit 10 corresponding to the area where the displacement has occurred
May be performed individually.

Incidentally, the size of the gantry unit 10 depends on the water depth of the target sea area.
Height from the bottom of the column to the top of the capital block 13 is 20
m, the outer diameter of one inclined column 12 is 1 m, and the degree of inclination is 1
5 degrees, the length of one side of the base slab 11 forming a quadrilateral is 1
The length of one side of the capital block 13 which is 2 m to 17 m and also a quadrilateral is about 5 m to 8 m. FIG.
Shows an embodiment of a configuration in which four inclined columns 12 are erected inwardly at an angle of 15 degrees in diagonal directions orthogonal to each other. A high-strength PC pile, that is, a prestressed high-strength concrete pile (PHC pile) is suitably used for the inclined column 12.

The gantry unit 10, which is a huge structure as described above, is manufactured in a construction yard on land, transported by sea to the site, and after positioning, is settled at a predetermined position on the sea bottom using a crane ship or the like. And install it. Therefore, offshore construction on site is minimal, and the construction period can be shortened. Adjacent gantry units 10 join the respective base slabs 11 and 11 to each other with an expansion joint or the like as necessary.

As shown in detail in FIG. 4, the structure for supporting the foundation beam 1 with the column cap block 10 is as follows. First, the pedestal 6 is provided on the upper surface of the column cap block 10 via the shear key 7 which resists a horizontal force. Is placed. In the case of FIG. 4, the pedestal 6 is firmly connected to the foundation beam 1 indirectly via a seismic isolation device 8 by means such as bolting. However, the configuration in which the base beam 1 is indirectly connected to the foundation beam 1 via the seismic isolation device 8 as shown in FIG. 4 is a result in consideration of the seismic isolation of the marine artificial ground, and is not essential. The same applies to a structure in which the base beam 1 is directly supported by the pedestal 6 and both are directly connected.

In any case, since the shear key 7 connecting the capital block 13 and the pedestal 6 resists the horizontal force at the time of an earthquake as described above, the shear key 7 has a concave portion 7a and a convex portion 7b which are fitted to each other. It consists of a combination with A gap s between the concave portion 7a and the convex portion 7b having a size capable of following the horizontal displacement transmitted from the seabed ground.
Is formed as a diameter difference between the concave portion 7a and the convex portion 7b (the invention according to claim 2).

In addition, since the present invention is based on the premise that so-called followability to uneven settlement of the seafloor ground is assumed, the column cap block 13 of the artificial offshore ground having the above-described structure is, as shown in FIG. It has a size and a shape having a space in which a required number of uneven settlement correcting jacks 9 can be vertically installed. Furthermore, the unequal settlement correction plate can be sandwiched between the pedestal 6 and the capital block 13 (the invention according to claim 3).

Therefore, when the construction method of the artificial offshore ground is carried out, it is necessary to adjust the height of the foundation beam 1 of the upper building or the structure, or the undersea ground generated in the service process after the artificial offshore ground is constructed. When it is necessary to correct for the differential settlement, the required number of differential settlement correction jacks 9 are vertically installed between the capital block 13 and the foundation beam 1 as shown in FIG. Then, the necessary amount of raising of the foundation beam 1 is performed by jack-up driving the differential settlement correction jack 9, and the required number of correction plates 20 are sandwiched in the gap between the pedestal 6 and the column cap block 13. Accordingly, the horizontality of the foundation beam 1 follows the uneven settlement, and is properly secured in a timely manner (the invention according to claim 5).

[0024]

[Effects of the present invention] The marine artificial ground according to the inventions according to claims 1 to 3, which is constructed by the construction method according to the inventions according to claims 4 and 5, is located on soft ground affected by uneven settlement. It is suitably implemented as a marine artificial ground. That is,
The `` follow-up type '' is capable of timely and appropriate correction processing in the unit of each gantry block only for the area where displacement has occurred for the uneven settlement that has occurred. Not only its own weight but also a place where there is a high possibility of deformation in the vertical and horizontal directions due to the load of the structure from the periphery. Further, the present invention can be similarly applied to a place where the settlement speed and the degree of deformation are different due to expansion and extension, and the operation is performed on the assumption that uneven settlement occurs. Moreover, because of the unitized structure, expansion and extension work can be easily performed in accordance with the capacity of the on-board facility.

In addition, since the space under the artificial ground has a free space between the inclined columns, there is no hindrance to the tidal current and there is little adverse effect on the surrounding environment. The space can be used effectively, and the fluctuation of the effective weight is small even in a place where the tide level varies greatly (tidal difference), so that the necessity for ballasts and mooring devices is reduced.

Furthermore, the artificial marine ground of the present invention is lighter in weight than the landfill method and the gravity type structure, so that the scale of improvement (depth) of the soft ground can be small. Since the part receiving buoyancy is small, the inertial force due to the earthquake is small, and the horizontal force due to the earthquake effectively resists the inclined strut, so that the advantage of high seismic resistance is great.

[Brief description of the drawings]

FIG. 1 is an elevation view showing an embodiment of a marine artificial ground according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is an elevational view showing another embodiment of the artificial marine ground according to the present invention.

FIG. 4 is an elevation view showing the connection between the gantry unit and the foundation beam.

FIG. 5 is a plan view of the gantry unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 Submarine ground 11 Base slab 12 Inclined support 13 Head block 10 Gantry unit 1 Foundation beam 13 Pedestal 7 Shear key 8 Seismic isolation device 7a Concave part 7b Convex part s gap 9 Pillar correction jack 20 Correction plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Go Nishinakagawa 8-21-1, Ginza, Chuo-ku, Tokyo Inside Takenaka Corporation Tokyo Main Store (72) Inventor Minoru Kawaharada 8-21 Ginza, Chuo-ku, Tokyo No. 1 Inside Takenaka Corporation Tokyo Main Store (72) Inventor Yasuaki Totsuka 8-21-1, Ginza, Chuo-ku, Tokyo Inside Tokyo Main Branch Takenaka Corporation (72) Inventor Hideaki Kawahara Hayashi Central Tokyo 8-21-1, Ginza-ku, Tokyo Takenaka Civil Engineering Corporation

Claims (5)

[Claims] 1. A base slab laid on a sea bottom, a plurality of inclined struts erected on the base slab at a height protruding to the sea by inclining in at least two directions orthogonal to each other, and A gantry unit constructed in an oar shape with a column head block firmly connected to the upper end is built on the sea floor, a group of multiple gantry units constitutes a marine artificial ground, foundation beams of upper buildings and structures Is supported horizontally, a pedestal is mounted on the upper surface of the capital block through a shear key, and the pedestal is directly or indirectly indirectly through a seismic isolation device or the like for the upper building or structure. Marine artificial ground characterized by being tied to the foundation beam. 2. A gap having a size capable of following horizontal displacement transmitted from the seabed ground is provided between a concave portion and a convex portion forming a shear key connecting the capital block and the pedestal. The marine artificial ground according to claim 1, characterized in that the marine artificial ground is formed as a diameter difference between the two. 3. The capital block is sized and shaped to have a space in which a required number of jacks for correcting settlement can be installed vertically between the foundation beam and the pedestal and the capital block. The marine artificial ground according to claim 1 or 2, wherein the plate is sandwiched therebetween. 4. The soft submarine ground is subjected to ground improvement by a deep mixing method, the seabed is leveled by abandoned stones, a base slab laid on the seabed, and at least orthogonal to the base slab. Incline in the direction, a plurality of inclined props built at the height protruding to the sea, and a gantry unit constructed on the land with a column head block that firmly connects the upper end of the inclined prop on the sea, and manufactured on land, By marine transportation and submerged and installed at a predetermined position on the sea floor, on the upper surface of each column cap block of the gantry unit,
Placing the pedestal via the shear key, constructing the foundation beam of the upper building or structure horizontally on the pedestal of each gantry block directly or indirectly through seismic isolation devices etc. , Each of which is characterized by the construction method of artificial marine ground. 5. Adjustment of the height of the foundation beam of the upper building or structure, or correction for uneven settlement of the seabed, install the required number of uneven settlement jacks vertically between the capital block and the foundation beam. 5. The sea according to claim 4, wherein the foundation beam is raised by jacking up with the jack, and a correction plate is sandwiched between the pedestal and the column cap block to secure the horizontality of the foundation beam. Construction method of artificial ground.