JP2004238993A - Impervious structure of revetment, and construction method for revetment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the impervious structure of a revetment and a construction method for the revetment dispensing with form removing work underwater and causing little unevenness in laying an impervious sheet. <P>SOLUTION: After improving the ground near the lower part of the revetment, a steel pipe sheet pile 3 is driven, and a precast slab 2 is installed with a prescribed space to the steel pipe sheet pile 3. A filler 4 is filled in a clearance between the steel pipe sheet pile 3 and the precast slab 2, and the impervious sheet 5 is laid in multilayer structure on the surface of the precast slab 2 to construct the impervious structure of the revetment. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water barrier structure for a seawall and a method for constructing a seawall to be constructed when a water area is partitioned and landfilled inside.
[0002]
[Prior art]
Construction of the final disposal site, which has been under construction using a V-shaped valley in the mountains, has recently shifted to offshore construction. The main reasons for this were the difficulty in securing a suitable place for construction, and the intensified anti-construction movement caused by concerns about leakage of sewage (leaching water) in the disposal site to the underground. Therefore, construction of a disposal site on the sea, which has a wide area, is being promoted away from the base of citizens' lives.
When constructing the above-mentioned marine disposal site, first, a seawall constituting the outer periphery of the disposal site is constructed by installing a caisson or by casting an underwater concrete b in place.
When the revetment is performed by casting the underwater concrete b in place, for example, the steel formwork a is installed, then the underwater concrete b is cast, and after the underwater concrete b hardens, the steel formwork a is released. (See FIG. 8). After that, a marine disposal site is constructed by laying a seepage control sheet on the inner side of the seawall of the concrete wall to form a seepage control structure.
[0003]
[Problems to be solved by the invention]
The above-mentioned conventional water barrier structure of the seawall and the method of construction of the seawall have the following problems.
<B> The revetment is constructed by installing steel formwork, placing underwater concrete, hardening the underwater concrete, and removing the formwork. However, there is a problem that the workability and the construction period are prolonged because of the underwater work.
<B> When attaching a water-impervious sheet to a steel pipe sheet pile surface or underwater concrete surface, the mounting surface is not smooth, so that the water-impervious sheet becomes uneven and it becomes difficult to attach the water-impervious sheet.
[0004]
[Object of the invention]
The present invention has been made in order to solve the above-described conventional problems, and an object of the present invention is to provide a seawall impermeable structure and a seawall construction method capable of reducing the amount of underwater work required for construction of a seawall. Another object of the present invention is to provide a water barrier structure for a seawall and a method for constructing a seawall where the watertight sheet is unlikely to be uneven when the watertight sheet is attached. It is another object of the present invention to provide a seawall structure and a seawall construction method that are excellent in seawater barrier performance.
The present invention achieves at least one of these objects.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the seawall structure of the revetment of the present invention to be constructed when partitioning the water area and performing reclamation on the inside, the improved ground in which the ground near the revetment lower portion is improved, and the revetment A steel pipe sheet pile provided on the outside water side of the steel pipe sheet pile, a precast plate provided inside the seawall of the steel pipe sheet pile, and a filler poured into a gap between the steel pipe sheet pile and the precast plate. It is a water barrier structure of a seawall.
In the water barrier structure of a seawall according to the present invention, a watertight sheet can be provided inside the seawall of the precast plate. In addition, the water-blocking sheet may have a multilayer structure.
Further, the method for constructing a seawall of the present invention for constructing the watertight structure of the seawall comprises a soil improvement step of forming an improved ground near the seawall lower part, a steel pipe sheet pile installation step of installing the steel pipe sheet pile, and the steel pipe sheet pile. A precast plate installation step of installing a precast plate inside the seawall, a filler material installation step of filling the gap between the steel pipe sheet pile and the precast plate with the filler material, and the inside of the seawall of the precast plate. This is a construction method including a water-impervious sheet installation step of installing a water-impervious sheet.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0007]
<A> Seawall In the present invention, seawall 1 is a partition embankment constructed when partitioning a water area and performing reclamation inside. For example, a revetment 1 surrounding a landfill, which is constructed when a landfill is constructed in the sea, corresponds to this (see FIG. 1). After the revetment 1 is constructed, the revetment inside 71 can be used as a disposal facility for general waste and the like.
The present invention relates to a water barrier structure when a seawall is constructed by a composite structure of a steel pipe sheet pile 3 and a filler 4 described later (see FIGS. 2, 3 and 4).
[0008]
When the revetment 1 is constructed on the sea surface, when the seabed under the constructed revetment 1 is soft or the bearing capacity cannot be secured, a known sand compaction pile method (SCP method) or a known deep mixing method (CDM method) ) Etc. are carried out by preceding construction. In addition, after the operation of the disposal site, the stability of the revetment 1 (dams) at all times at the time of the predetermined waste input or during an earthquake, etc. (arc sliding, sliding, etc.) will be examined. The above-described ground improvement can be performed even when it is necessary to ensure stability. Here, with the sand compaction pile method, a casing pipe with a vibrator (vibratory hammer) attached to the upper part is poured into the ground, the casing pipe is pulled out while sand is charged inside the casing, and further driven back, This is a method of creating an improved ground (sand pile 61) that is tightened thicker than the pipe diameter. On the other hand, the deep mixing processing method (CDM method) is a method of forming an improved ground (deep mixing processing soil 62) by stirring and mixing a cement-based slurry or mortar and soft ground to a predetermined strength in situ. That is.
When the sand pile 61 and the deep mixed treated soil 62 are formed on the seabed ground, as shown in FIG. 5A, it can be performed by using a ground improvement ship 91 or the like.
The method for improving the ground of the seabed is not limited to the above-described SCP method and CDM method, and any method capable of exhibiting a desired improvement effect can be used while taking into account the construction period and cost.
[0009]
After the ground improvement work, the steel pipe sheet pile 3 which is a component of the revetment 1 of the present invention is cast. When the steel pipe sheet pile 3 is driven into the seabed, the pile driving ship 92 can be used as shown in FIG. 5B. In addition, the steel pipe sheet piles 3 are arranged in parallel in two rows at a fixed interval, the respective heads of the opposed steel pipe sheet piles 3 are connected by tie rods 31, and a filling material or the like is filled between the parallel steel pipe sheet piles 3. Thus, a double steel pipe sheet pile type revetment can be provided (see FIG. 6A).
[0010]
<B> Water-blocking structure The purpose of the water-blocking structure at the disposal site is to use the ground, such as an impermeable layer or a poorly permeable layer, or use artificial materials as surface water-blocking, and use the water in the garbage or in the landfill. The purpose of the present invention is to prevent pollution of public waters and groundwater by rainwater (leaching water) that has fallen, and to prevent adverse effects on the surrounding environment due to these. In the case of a sea surface disposal site, the impermeable structure can be formed using an artificial material such as the impermeable sheet 5. Surface impervious works are like applying impervious works to the bottom of a landfill and the entire surface of a slope to create a container for storing water.
The impermeable structure in the present invention is formed by a multi-layered structure of the steel pipe sheet pile 3, the filler 4, the precast plate 2, and the impermeable sheet 5. Here, it is preferable that the water shielding sheet 5 has a double or triple multilayer structure.
As the water-blocking sheet, a sheet of a synthetic rubber type, a synthetic resin type, an asphalt type, a bentonite type, a laminated type composite type or the like can be used. Examples of the synthetic rubber-based sheet include an ethylene propylene diene monomer sheet, an EPDM fiber composite sheet, and a polyolefin-based elastomer sheet. Examples of the synthetic resin sheet include a polyvinyl chloride sheet, a high-density polyethylene sheet, and a polyurethane sheet. As the asphalt-based sheet, for example, an all-layer impregnated-type asphalt sheet or a laminated-type asphalt sheet can be used.
[0011]
As shown in FIG. 7, the method of laying the water-impervious sheet 5 can be performed by laying the water-impervious sheet 5 on the surface of a precast plate 2 described later while suspending the water-impervious sheet 5 by a crane ship 93 or the like. In this case, the diver 95 can perform the installation of the impermeable sheet 5 and the fixing of the rope at the overlapping portion between the impermeable sheets 5. The water-blocking sheet 5 can be attached to the precast plate 2 described later with the attachment fitting 8.
[0012]
<C> Precast plate The precast plate 2 is installed inside the revetment 1 of the steel pipe sheet pile 3 at a predetermined interval from the steel pipe sheet pile 3 and fills a gap between the steel pipe sheet pile 3 and the precast plate 2 with a filler 4 described later. belongs to. Since the precast plate 2 itself also has a predetermined strength and water impermeability, it can be expected to have an effect as a constituent member of the water barrier structure and as a structural member of the seawall 1.
In the conventional method of placing the steel formwork a temporarily and casting the underwater concrete b, the installation and demolding of the formwork are underwater work, so that problems such as workability and prolonged construction time have occurred. By disposing the plate 2, the work of removing the formwork is not required, and the above problem can be solved. In addition, by shaping the surface of the precast plate 2 into a smooth surface, unevenness of the sheet when laying the impermeable sheet 5 does not occur, and the danger of leaking out of the leachate from the sheet overlapping portion is eliminated.
The precast plate 2 can be made of, for example, a cement-based material.
[0013]
The precast plate 2 manufactured to a predetermined size is lowered by a crane ship 93 or the like along the CT steel 81 attached to the steel pipe sheet pile 3 inside the seawall 1 of the steel pipe sheet pile 3 and is installed at a predetermined interval. . At the time of installation, the diver 95 can ensure the installation accuracy (see FIG. 6A).
[0014]
<D> After the filler precast plate 2 is installed, the gap between the steel pipe sheet pile 3 and the precast plate 2 is filled with the filler material 4, whereby the steel pipe sheet pile 3 and the precast plate 2 can be integrated. As the filler 4, for example, underwater concrete can be used.
As shown in FIG. 6B, the filling material 4 can be cast by a mixer ship 94 or the like.
By placing the upper concrete 41 on the upper part of the steel pipe sheet pile 3 after placing the filler material 4, the protection of the upper part of the steel pipe sheet pile 3 and the continuous steel pipe sheet pile 3 can be integrated at the upper part.
[0015]
【Example】
Hereinafter, an embodiment of the seawall construction method of the present invention will be described with reference to the drawings.
[0016]
<E> Ground improvement process An improved ground is created near the lower part of the revetment 1 by sand compaction pile method or deep mixing method (see Fig. 5 (a)). At this time, in consideration of the results of the examination of the arc slide of the revetment 1 (including the load of the refuse after the start of operation), a plurality of ground improvement methods that divide the sand pile 61 formation area and the deep mixed treated soil 62 formation area into They can be used together. That is, the sand pile 61 sets the respective improved areas so that the shear resistance frictional force of the sand can be exhibited, and the deep mixed soil 62 can exhibit the shear resistance adhesive force of the mixed soil. .
Further, a replacement method in which the seabed ground surface (the upper surface of the sand pile 61 and the deep mixed soil 62) near the steel pipe sheet pile 3 on the seawall 71 is replaced with the premixed soil 63 may be used. By using this method, the seafloor ground surface (the upper surface of the premixed soil 63) is formed smoothly, and the laying of the impermeable sheet 5 does not cause unevenness of the sheet. And the water-shielding of the connection portion can be increased. As a countermeasure for preventing the premixed soil 63 from flowing out, it is preferable to construct the embankment with rocks 64 or the like as shown in FIG. In addition, the above-mentioned replacement method can play a role of a bottom form when the filler 4 is cast by performing after the lowermost precast plate 2 is installed.
[0017]
<F> Steel pipe sheet pile installation process In the ground improvement process, sand compaction pile method or deep mixing method is applied near the lower part of the revetment 1 and then the steel pipe sheet pile 3 is cast on the seabed ground. The driving of the steel pipe sheet pile 3 can be performed by a pile driving boat 92 or the like (see FIG. 5B). In addition, the steel pipe sheet piles 3 are arranged in parallel in two rows at a fixed interval, the respective heads of the opposed steel pipe sheet piles 3 are connected by tie rods 31, and a filling material or the like is filled between the parallel steel pipe sheet piles 3. The double-walled sheet pile type revetment constructed in this way can also be used. In such a case, it is preferable to shift to a precast plate installation step described later after driving parallel steel pipe sheet piles and connecting them with tie rods 31. The filling of the filling material may be performed after the steel sheet pile 3 is cast or after a water-impervious sheet installation step described later.
[0018]
<G> Precast plate setting process After the steel pipe sheet pile setting process, the precast plate 2 manufactured to a predetermined size is suspended by the crane ship 93 while the steel pipe sheet pile 3 is provided inside the seawall 1 at a predetermined interval. We will set up with. Since the installation of the precast plate 2 is an underwater operation, it is necessary to ensure the mounting of the precast plate 2 at a predetermined position by the diver 95 and to ensure the accuracy of the mounting (see FIG. 6A).
[0019]
<H> Filling Material Application Step After the precast plate setting step, the gap between the steel pipe sheet pile 3 and the precast plate 2 is filled with the filler 4. The filling material 4 can be cast by a mixer ship 94 or the like (see FIG. 6B).
[0020]
<I> Water Impermeable Sheet Installation Process After the filling material application process, the water impermeable sheet 5 is installed on the surface of the precast plate 2 using the crane ship 93. That is, the impermeable sheet 5 is suspended by the crane ship 93, and the diver 95 attaches the impermeable sheet 5 to the surface of the precast plate 2 with the mounting bracket 8. It is preferable that the water impermeable sheet has a double or triple multilayer structure. In addition, the diver 95 can fix the rope on the overlapping portion of the water-blocking sheet 5 and the like. The impermeable sheet 5 can also be laid after draining the water on the inner revetment wall 71. Further, the overlapping portion of the water-blocking sheet 5 can be joined by welding after draining the water on the inside of the seawall 71.
[0021]
【The invention's effect】
The water barrier structure of the revetment and the method of constructing the revetment of the present invention are as described above, and the following effects can be obtained.
<A> Since the precast plate is used, it is not necessary to remove the mold from the mold in water, and the workability can be improved and the construction period can be shortened.
<B> Since a precast plate manufactured with a smooth surface is used, the mounting surface of the water-impervious sheet becomes smoother and unevenness of the water-impervious sheet is less likely to occur, so that quality can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating an embodiment constructed so as to surround a seawall provided with a water shielding structure of the present invention.
FIG. 2 is a cross-sectional view illustrating a water barrier structure of a seawall according to the present invention, and is a view taken along the line AA in FIG.
FIG. 3 is a front view of the revetment for explaining the water barrier structure of the revetment of the present invention.
FIG. 4A is a view taken in the direction of arrows BB in FIG. (B) The CC arrow view of FIG.
FIG. 5 (a) is an explanatory view illustrating a ground improvement step in the seawall construction method of the present invention. (B) Explanatory drawing explaining the steel pipe sheet pile installation process.
FIG. 6 (a) is an explanatory view illustrating a precast plate installation step in the seawall construction method of the present invention. (B) Explanatory drawing explaining the filling material construction process.
FIG. 7 is an explanatory view illustrating a water-impervious sheet installation step in the seawall construction method of the present invention.
FIG. 8 is an explanatory view for explaining that a formwork is removed underwater in a conventional seawall construction method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Revetment 2 ... Precast plate 3 ... Steel pipe sheet pile 4 ... Filling material 5 ... Waterproof sheet 71 ... Inside of revetment 72 ... Outside water side

Claims (3)

It is a water barrier structure of a revetment built when partitioning the water area and reclaiming it inside.
Improved ground that improved the ground near the seawall lower part,
Steel pipe sheet piles provided on the outer water side of the seawall,
A precast plate provided inside the seawall of the steel pipe sheet pile,
It is characterized by comprising a filler poured into the gap between the steel pipe sheet pile and the precast plate,
Water barrier structure of revetment. The water barrier structure of a seawall according to claim 1, wherein a waterproof sheet is provided inside the seawall of the precast plate. A seawall construction method for constructing a seawall impermeable structure according to claim 1 or 2,
Ground improvement process of creating an improved ground near the seawall lower part,
Steel pipe sheet pile installation step of installing the steel pipe sheet pile,
A precast plate installation step of installing a precast plate inside the seawall of the steel pipe sheet pile,
A filler application step of filling the filler in the gap between the steel pipe sheet pile and the precast plate,
A water-impervious sheet installation step of installing the water-impervious sheet inside the seawall of the precast plate,
Construction method of revetment.

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