JP4040383B2 - Construction method for underwater foundation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an underwater foundation construction method for compacting mounds such as caisson revetments and foundation ground.
[0002]
[Prior art]
Conventionally, there is a method of compacting the foundation ground by a vacuum consolidation method as disclosed in JP 2000-104242 A or the like. The vacuum consolidation method is a method for improving soft and viscous ground such as landfill layer, sludge layer, peat layer, etc. Drain materials such as paper drain and sand pile are installed in the vertical direction in the ground, and the upper end A non-woven fabric or a water-permeable material such as a perforated pipe that communicates with the vacuum pump is placed on the top, the top of this water-permeable material is sealed with an airtight sheet, and the water contained in the soft viscous ground is further activated by operating the vacuum pump. In addition, the air is discharged through a drain material or a water flow material.
[0003]
In the above Japanese Patent Laid-Open No. 2000-104242, in the conventional vacuum consolidation method, a drain material placing step, a water-permeable material installation step such as a nonwoven fabric and a perforated pipe, and an air-tight sheet laying step are independent devices. Each process can be performed only after the previous process is completely completed, and there is a disadvantage that work is intermittent and construction efficiency is low. In extremely soft ground, it is difficult to work with a conventional drain material placement machine, or it is necessary to create a temporary construction ground prior to construction, and these constructions take several times longer than normal soft ground. However, it was made possible to perform all the steps of laying an airtight sheet and forming a vacuum consolidation yard on soft underwater ground.
[0004]
[Problems to be solved by the invention]
However, the compaction by the vacuum consolidation method has an effect on the foundation ground, but the mound portion that becomes the caisson foundation on the foundation ground cannot be compacted. This is because the mound portion is usually constructed with sand and sand mat and is formed by dropping material from the sea, so that the portion cannot be sufficiently compacted.
[0005]
An object of the present invention is to provide an underwater foundation construction method capable of eliminating the inconveniences of the conventional examples and compacting the mound portion and simultaneously promoting consolidation of the foundation ground.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention lays a water shielding material so as to cover the mound constructed on the foundation ground, installs a pipe on the mound through the water shielding material, and connects to the drain pump inside. An enclosure with a water shielding wall of a fume pipe provided with a drainage facility with a water pipe is installed on the mound so as to surround the outer periphery of the pipe, and a gap between the fume pipe and the water shielding material is filled with a filling material such as asphalt mastic. Filling, and operating the drainage equipment in the enclosure, sucking the water in the mound and foundation ground from the piping during drainage, generating suction on the mound and foundation ground, and compacting these, and The gist is to extend and fix the end of the water shielding material so as to overlap the foundation ground around the mound.
[0007]
According to the first aspect of the present invention, the water in the mound and the foundation ground can be sucked from this pipe by the drainage equipment inside the enclosure with the water shielding wall, and suction is generated in both the mound and the foundation ground. These can be compacted. And the enclosure in a water-impervious wall can be reused for the next construction, and can also be constructed continuously by a fixed cycle.
[0008]
Moreover, it can economically and simply construct by constructing it using piping and the enclosure in the impermeable wall which has a drainage system beforehand.
[0009]
According to the second aspect of the present invention, in addition to the above-described function, the end of the water shielding material can exhibit the scouring prevention effect by being extended so as to be polymerized on the foundation ground around the mound. The edge of the water shielding material is turned up by tides, etc., and fixed so that seawater does not flow in from there, so that a gap is created between the seat and the ground, and the reduction effect of the compaction effect due to the suction force can be prevented .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail. FIGS. 1-7 is a side view of each process showing one embodiment of the construction method of an underwater foundation according to the present invention. In the figure, 1 is an underwater foundation ground, and 2 is a mound constructed on the foundation ground 1. .
[0011]
As will be described later, the mound 2 is constructed by selecting in advance a material in which the compaction effect due to the suction of water remains even after the suction is stopped, that is, a material having a good particle size distribution to which a compaction effect can be expected. . For example, a large stone such as a discarded stone is unsuitable because it is difficult to compact with a suction pressure of 1 kg / cm ^{2 at} the maximum, but by laying a large discarded particle 3 on the surface of the mound 2, It is possible to easily generate suction in the entire mound 2. In this case, the material constituting the mound 2 inside the discarded stone 3 is clay or sand such as buried soil.
[0012]
As shown in FIG. 1, a water shielding material 4 is laid on the mound 2 so as to cover it. The water shielding material 4 is a viscous liquid before solidification, such as asphalt mastic, which can be formed by pouring with a pump or the like (FIG. 1 (a)), or an existing material such as a rubber mat. A mat or a mat produced in a land yard such as an Alfalt mat is laid [FIG. 1 (b)]. Further, underwater concrete, underwater mortar, and the like are also applicable as the water shielding material 4.
[0013]
The end 4a of the water-impervious material 4 is extended to be superposed on the foundation ground 1 around the mound 2 and fixed. As this fixing method, as shown in FIG. 10, the weight 5 made of precast concrete or a metal having a high specific gravity is used to hold the end 4a of the water shielding material 4 as shown in FIG. The end 4a of the water shielding material 4 is embedded in the ground together with the water shielding wall 7 as shown in FIG. 12, and the underwater non-separable concrete 8 is formed as shown in FIG. For example, you can place it and hold it. When the specific gravity of the water shielding material 4 is large and no lifting occurs, these measures can be omitted.
[0014]
As described above, the water shielding material 4 is disposed so as to cover the mound 2 constructed on the foundation ground 1, and then the pipe 9 is passed through the water shielding material 4 as shown in FIGS. 2 and 3. Install on top. The pipe 9 is not particularly limited, but may be a small diameter pipe.
[0015]
The pipe 9 may be made of steel, concrete, synthetic resin, or the like. However, the pipe 9 may be installed on the mound 2 through the water shielding material 4 as shown in FIGS. In addition, as shown in FIG. 8, the pipe 9 may be installed on the mound 2 before the water shielding material 4 is laid, and then laid after that. As described above, this is possible when the water shielding material 4 is a viscous liquid before solidification, such as asphalt mastic, and can be poured by a pump or the like.
[0016]
As shown in FIG. 3 and FIG. 4, a surrounding body with a water shielding wall of a fume pipe 11 provided with a drainage facility 10 such as a drainage pump or a water pipe connected to the inside is mounded so as to surround the pipe 9. 2 is installed. A fume tube 11 is suitable as the tube body of the water shielding wall.
[0017]
At that time, the gap between the fume tube 11 and the water shielding material 4 is filled with a filler 13 such as asphalt mastic.
[0018]
As another embodiment, as shown in FIG. 9, a water shielding material 4 in which a pipe 9 is integrated is laid (a), and the other water shielding material 4 ′ includes the periphery of the water shielding material 4. The other part may be covered (b), and the gap between the water shielding material 4 and the water shielding material 4 'may be filled with a filler 13 such as asphalt mastic.
[0019]
Thus, if the water shielding material 4 is laid so as to cover the mound 2 and a pipe body such as the fume pipe 11 provided with the pipe 9 and the drainage equipment 10 is installed, the drainage equipment as shown in FIG. 10 is operated and the fume pipe 11 is drained. By sucking the water in the mound 2 and the foundation ground 1 from the pipe 9 at the time of drainage, suction is generated in the mound 2 and the foundation ground 1 and these are compacted.
[0020]
When the suction is completed, the fume pipe 11 is pulled up as shown in FIG. 6, and the caisson 14 is installed on the mound 2 as shown in FIG. At this time, the pipe 9 may be buried as it is.
[0021]
As shown in FIG. 14, for example, if the sand compaction pile 15, the sand drain 16, and other drain materials are disposed on the foundation ground 1, the consolidation of the mound 2 and the foundation ground 1 by the drainage is promoted. can do. FIG. 15 shows the state of revetment completion. In the figure, 17 is a landfill board.
[0022]
【The invention's effect】
As described above, the construction method of the underwater foundation of the present invention is intended to increase the strength of the ground by pumping groundwater to form a suction action area in the ground, and also to the mound part on the foundation ground. At the same time, consolidation of the foundation ground can be promoted.
[0023]
The enclosure at the impervious wall can be reused for the next construction, can be constructed continuously in a certain cycle, and the impervious wall has drainage equipment in the interior in advance. It can be constructed economically and easily by constructing using the Go body.
[Brief description of the drawings]
FIG. 1 is a side view of a first step showing an embodiment of an underwater foundation construction method of the present invention.
FIG. 2 is a side view of a second step showing an embodiment of the underwater foundation construction method of the present invention.
FIG. 3 is a side view of a third step showing an embodiment of the underwater foundation construction method of the present invention.
FIG. 4 is a side view of a fourth step showing an embodiment of the underwater foundation construction method of the present invention.
FIG. 5 is a side view of a fifth step showing one embodiment of the underwater foundation construction method of the present invention.
FIG. 6 is a side view of a sixth step showing an embodiment of the underwater foundation construction method of the present invention.
FIG. 7 is a side view of a seventh step showing an embodiment of the underwater foundation construction method of the present invention.
FIG. 8 is an explanatory view showing another method of disposing a water shielding material in the construction method for an underwater foundation of the present invention.
FIG. 9 is an explanatory view showing still another method of disposing the water shielding material and the pipe 9 in the underwater foundation construction method of the present invention.
FIG. 10 is a side view showing a first example of fixing an end portion of a water shielding material in a construction method for an underwater foundation according to the present invention.
FIG. 11 is a side view showing a second example of fixing an end portion of a water shielding material in an underwater foundation construction method of the present invention.
FIG. 12 is a side view showing a third example of fixing the end portion of the water shielding material in the underwater foundation construction method of the present invention.
FIG. 13 is a side view showing a fourth example of fixing an end portion of a water shielding material in an underwater foundation construction method of the present invention.
FIG. 14 is a perspective view showing an embodiment of an underwater foundation construction method according to the present invention.
FIG. 15 is a perspective view of a revetment completed by the underwater foundation construction method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Foundation ground 2 ... Mound 3 ... Discard stone 4, 4 '... Water shielding material 4a ... End 5 ... Weight 6 ... Metal net 7 ... Water shielding wall 8 ... Underwater non-separation concrete 9 ... Piping 10 ... Drainage equipment 11 ... Hume pipe 12 ... Mound 13 ... Filler 14 ... Caisson 15 ... Sand compaction pile 16 ... Sand drain 17 ... Landfill

Claims (2)

A fume pipe with a water shielding material laid over the mound constructed on the foundation ground, a pipe installed on the mound through the water shielding material, and a drainage facility with a water pipe connected to the drain pump inside An enclosure with a water-impervious wall is installed on the mound so as to surround the outer periphery of the pipe, and the gap between the fume pipe and the water-impervious material is filled with a filler such as asphalt mastic, and the drainage equipment in the enclosure is installed. A construction method for underwater foundations that operates and sucks the mound and foundation ground from the pipes during drainage to generate suction on the mound and foundation ground and compacts them.   The construction method of the underwater foundation according to claim 1, wherein the end of the water shielding material is extended and fixed so as to be superimposed on the foundation ground around the mound.

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