JP7564685B2 - Water-impermeable structure of seawall at marine disposal site - Google Patents

Description

The present invention relates to a waterproof structure for a seawall at a sea surface disposal site, and in particular to a waterproof structure for a seawall at a sea surface disposal site that ensures waterproofing at the seawall base of the waterproof sheet installed on the waterproof seawall constructed to surround the landfill area when constructing a sea surface disposal site, the waterproof sheet joints in the vertical waterproofing works, and the fixed parts to the waterproof seawall structure.

Conventionally, marine final disposal sites for municipal and industrial waste are constructed by dividing the area into sections using multiple caissons, cells, and other revetment structures with waterproof joints to create a waterproof revetment. On the landfill side, various waterproof structures using waterproof sheets, etc. are constructed to prevent the leakage of waste and retained water from the managed waste final disposal site, which is surrounded by the revetment structure and foundation ground after operation, into the surrounding sea and land areas.

The basic structure of these waterproof structures is specified in the "Ministry Ordinance Prescribing Technical Standards for Final Disposal Sites for Municipal Waste and Industrial Waste (hereinafter, Standards Ministerial Ordinance)" (Non-Patent Document 1). Figure 15 is a schematic cross-sectional view of an example of a sea surface disposal site constructed in which the sea surface is partitioned by a waterproof revetment 50 using solidified treated soil 59 as backfill soil, after landfilling with waste 58 has been completed. The landfill area 62 that will become this sea surface disposal site is partitioned by a caisson-type composite embankment on the front side of the waterproof revetment and steel sheet piles 56 on the back side, with the interior backfilled with solidified treated soil 59 and partitioned by the waterproof revetment 50.

The caisson-type composite embankment has a caisson 64 installed on a rubble mound 53 constructed on a deep mixed soil layer 52, and a surface waterproofing work 70 consisting of a waterproof sheet 71 is formed along the slope of the rubble mound 53 on the landfill area 62 side. A riprap 57 is constructed as an upper covering layer on top of the surface waterproofing work 70 so as to cover the entire surface waterproofing work 70.

On the other hand, an outer vertical waterproofing work 75 consisting of a waterproof sheet 71 having the same structure as the surface waterproofing work 70 is applied over the entire outer surface (landfill area 62 side) of the steel sheet pile 56 on the rear side, and the landfill area 62 behind it (inland side) is filled with the transported waste 58.

In this way, marine disposal sites are generally constructed as managed waste landfill revetments with waterproofing added to each part of the landfill revetment structure. For example, asphalt mastic base protection layer 30 is formed between surface waterproofing 70 laid to cover the slope and top of rubble mound 53 as the waterproofing work for each part and the base of caisson 64. In such surface waterproofing 70, in order to ensure waterproofing at the joints between the holding block 33 constructed to hold down the waterproof sheet 71 and the waterproof sheet 71 and caisson 64, it is necessary to ensure the minimum length (seepage path length) required for the asphalt mastic base protection layer 30 and the waterproof sheet 71 to adhere closely to each other.

Of these components, the steel sheet piles 56 on the rear side of the water-impermeable revetment 50 are erected with a specified embedment length in the deep mixed soil layer 52, and the landfill area 62 is defined with the top of the piles held in place by tie rods T with caissons 64 as retaining structures.

The steel sheet piles 56 are thus required to function as impermeable walls, and to prevent deterioration of the structural performance due to aging, an outer vertical waterproofing structure 75 is attached to the entire surface of the outer side (the landfill area 62 side) of the steel sheet piles 56. The outer vertical waterproofing structure 75 uses a waterproof sheet 71 with a laminated sheet structure.

In the outer vertical waterproofing work 75 of the steel sheet piles 56, the erection of the steel sheet piles 56 and the installation of the waterproof sheet 71 on the surface of the steel sheet piles 56 are not carried out in the winter but are carried out across fiscal years. At this time, at the boundary between each work section (for example, between the work section of the current year and the work section of the next year), the end 71a (Figs. 16 and 17) of the waterproof sheet fixed to the caisson 64 needs to be kept stable at all depths in the sea during the construction suspension period. In addition, because a divided section 15 where the waterproof sheet 71 is not continuous occurs at the work section boundary, it is necessary to ensure waterproofing at the end 71b of the waterproof sheet 71 that is divided at the work section boundary.

A sheet connection structure has been proposed to ensure watertightness at the ends of such waterproof sheets at the divided parts (Patent Document 1). At the joints of the waterproof sheets provided in this sheet connection structure, the frame of the connector is placed over the ends of the sheets so as to cover each end of the waterproof sheets to be joined, and the inside is filled with a waterproof material such as an asphalt mixture.

Patent No. 4441240

Environment Agency, Laws, Notifications and Notices, "Ministry Ordinance on Technical Standards for Final Disposal Sites for General Waste and Final Disposal Sites for Industrial Waste", [online], last updated: Amended and published on June 9, 2017, Ministry of the Environment, [searched on March 6, 2020], Internet <URL: https://elaws.e-gov.go.jp/search/elawsSearch/elaws_search/lsg0500/detail?lawId=352M50000102001&openerCode=1>

The asphalt mastic base layer 30, in which the ends of the waterproof sheet 71 are held, is formed by filling a section surrounded by holding concrete blocks 33 as partition forms with asphalt mastic in a fluid state, and then cooling and solidifying. In the asphalt mastic base layer 30, the seepage path length L corresponds to, for example, the length of the bottom edge of the base layer 30, and it is required to ensure that L>1,250 mm (for example, 1,250 mm = required contact length 500 mm x safety factor 2.5). In addition, even at the base of the steel sheet pile 56, the surface of which is covered with the vertical waterproofing work 75, the ends of the waterproof sheet 20 must be held in contact with the waterproof sheet 20, the asphalt mastic base layer 30, and the treated soil surface by holding blocks 33, etc., to ensure sufficient waterproofing performance.

However, there are cases where the distance between the base of the caisson 64 installed on the rubble mound 53 and the toe of the rubble mound 53 is short, making it impossible to ensure the bottom length of the asphalt mastic foot protection layer, or where the structure of the joints of the waterproof sheet 71 makes it impossible to ensure the infiltration path length.

In the sheet connection structure disclosed in Patent Document 1, it is possible to maintain the waterproofing performance at the ends of each waterproof sheet at the joints of the waterproof sheets, but when the process of joining each waterproof sheet is included, no consideration is given to holding the waterproof sheet ends in a stable state at the separated points or ensuring waterproofing in that state.

In addition, in the vertical waterproofing work 75, as shown in Figures 16 and 17, it is necessary to reliably perform waterproofing at the sheet end 71a of the waterproof sheet 71, which is the fixed part to the structure such as the caisson 64, and at the sheet end 71b at the joint of the waterproof sheet 71, over the entire height in the depth direction.

The object of the present invention is to provide a waterproof structure for a seawall at a sea surface disposal site that ensures sufficient waterproofing at the ends of the waterproof sheet at the base fixing portion, the ends of the sheet at the fixing portion to the structure, and the ends of the waterproof sheet at the divided portion, by ensuring a sufficient seepage path length between the ends of each part of the waterproof sheet fixed in the asphalt mastic waterproof portion and the asphalt mastic, in order to solve the problems of the conventional technology described above.

In order to achieve the above object, the waterproof structure of the present invention for a sea surface disposal site revetment is a waterproof structure in which an end of a waterproof sheet constituting a waterproof layer laid on a waterproof base surface supporting the revetment structure is fixed to a base of the revetment structure constructed to divide the sea surface disposal site revetment via a footing waterproof layer formed by filling an impermeable waterproof material, the footing waterproof layer being made of a cooled and solidified asphalt mastic footing layer filled in a space between a retainer provided on the waterproof sheet and the revetment structure , and the end of the waterproof sheet is fixed to the revetment structure via a footing waterproof layer formed by filling an impermeable waterproof material. a first intermediate waterproof sheet is welded to the waterproof sheet so as to be in close contact with the base of the structure, the first intermediate waterproof sheet is welded to the waterproof sheet so as to be in close contact with the base of the structure and the retaining work, and the first intermediate waterproof sheet is welded to the waterproof sheet so as to be able to maintain the shape of the waterproof sheet standing up from the waterproof sheet of the waterproof layer; and in addition to the first intermediate waterproof sheet, at least one second intermediate waterproof sheet is welded to the waterproof sheet between the first intermediate waterproof sheet and the revetment structure, the second intermediate waterproof sheet is welded to the waterproof sheet so as to be able to maintain the shape of the waterproof sheet standing up from the waterproof sheet within the base waterproof layer;
The method is characterized in that the seepage path length between the surface of the root-protection water-proofing layer and the water-proof sheet is extended via the surfaces of the first intermediate water-proof sheet and the second intermediate water-proof sheet .

It is preferable that the second intermediate waterproof sheet has a length shorter than that of the first intermediate waterproof sheet and is embedded in the root protection waterproof layer so as to maintain the erected shape.

The length of the second intermediate waterproof sheet is preferably half the length of the first intermediate waterproof sheet.

The waterproof layer is preferably made of a laminated sheet of a waterproof sheet and protective mats sandwiching both sides of the waterproof sheet.

The impermeable water-blocking material is preferably selected from asphalt-based materials, concrete-based materials, soil-based materials, and chemical-based materials that have a predetermined water-blocking performance.

A side cross-sectional view showing the caisson and rubble mound near the top of a caisson-type composite breakwater at a marine disposal site (see Figure 15 as an example of the overall structure) in which one embodiment of the waterproofing structure for the seawall at a marine disposal site of the present invention is used. FIG. 2 is an enlarged cross-sectional side view showing a base portion of the waterproof structure shown in FIG. 1 . FIG. 16 is an enlarged cross-sectional side view showing an embodiment in which the waterproof structure of the present invention is applied to the upper end of the embedded portion of the steel sheet pile shown in FIG. 2 is an enlarged cross-sectional side view showing another embodiment of the water impermeable structure shown in FIG. 1 . FIG. 11 is an enlarged cross-sectional side view showing a waterproof structure according to still another embodiment. FIG. 11 is a side cross-sectional view showing the overall structure of another embodiment of a water-proof structure for a steel sheet pile. An enlarged side cross-sectional view showing the waterproof structure near the upper end of the embedded portion of the steel sheet pile. FIG. 16 is a partial plan view showing an embodiment in which the waterproof structure of the seawall of a marine disposal site of the present invention is applied to a caisson-type composite breakwater at a marine disposal site (FIG. 16 is an example of the waterproof structure). FIG. 9 is an enlarged partial plan view showing one embodiment of a waterproof structure of the end of the waterproof sheet at the waterproof sheet separation portion (IX) shown in FIG. 8 . FIG. 10 is a partial plan view showing a modified example of the branched waterproof sheet shown in FIG. 9 . FIG. 4 is a partial plan view showing another embodiment of the waterproof structure at the end of the waterproof sheet. A partial plan view showing an enlarged view of one embodiment of the waterproof structure of the end of the waterproof sheet at the caisson side anchorage (XII) shown in Figure 8. FIG. 4 is a partial plan view showing another embodiment of the waterproof structure at the end of the waterproof sheet. FIG. 4 is a partial plan view showing yet another embodiment of the waterproof structure at the end of the waterproof sheet. FIG. 1 is a side cross-sectional view showing the overall structure of an example of a conventional waterproof structure for a seawall at a sea surface disposal site. A partial plan view showing the installation state of caissons and steel sheet piles in a vertical waterproofing structure of a conventional seawall at a marine disposal site, as well as examples of the positions of the caisson side anchorages and waterproofing sheet separation parts. A partial front view showing the installation state of the caisson and steel sheet pile shown in Figure 16, the caisson side anchorage part, and an example of the position of the waterproof sheet dividing part.

Below, the embodiment of the waterproof structure for the seawall of a marine disposal site of the present invention will be explained with reference to the attached drawings.

[Configuration of the waterproof structure at the base of the surface waterproof structure]
Fig. 1 shows an embodiment in which the waterproof structure of the present invention is applied to a joint between the base of a caisson 4 of a waterproof revetment and the end of a rubble mound 3 of a sea surface disposal site of the same scale as the sea surface disposal site illustrated in Fig. 15. Fig. 2 shows an enlarged view of the waterproof structure between the base of the caisson 4 at the top end portion of the rubble mound 3 of Fig. 1.

The caissons 4 shown in Figure 1 are installed on a rubble mound 3 constructed on a deep mixed treated soil layer 52 (Figure 15) as a structure on the front side (ocean side) of the waterproof revetment 1 that divides the sea surface disposal site. The caissons 4 are made of known reinforced concrete, steel, or hybrid boxes filled with filler sand inside, and multiple caissons 4 of the same shape are arranged in a row on the rubble mound 3, and their backs are backfilled with a treatment level of 9. This allows them to function as a structure on the front side of the waterproof revetment 1 that divides the landfill area 11 (Figure 15) of a specified area and width in the coastal waters.

As shown in Figures 1 and 2, the caisson 4 is installed at approximately the center of the width of the top of the rubble mound 3. A surface waterproofing work 10 is laid on the slope of the rubble mound 3 so as to cover the entire slope from the top to the bottom of the slope of the rubble mound 3, and a prescribed layer of protective rubble 5 is piled on top of the work to protect the surface waterproofing work 10. Furthermore, the upper end of the surface waterproofing work 10 is extended to cover the top surface of the rubble mound 3, on which a prescribed layer of crushed stone 7 for preventing asphalt mastic penetration has been laid.

The surface waterproofing work 10 is composed of a three-layer laminated sheet in which both sides of the waterproof sheet 20 as the core material are laminated with protective mats 22. The waterproof sheet 20 is composed of a low-density polyethylene sheet (LLDPE: thickness 3 mm), and the upper and lower surfaces are laminated with nonwoven fabric as protective mats 22, forming a three-layer laminated sheet. By arranging the nonwoven fabric as protective mats 22 laminated on both sides of the waterproof sheet in this way, the nonwoven fabric comes into contact with the surface of the backfill material of the rubble mound 3, and a large static friction force and a buffering effect can be secured between the backfill material and the waterproof layer. Other materials suitable for the waterproof sheet include polyvinyl chloride (PVC) sheets, laminated sheets of nonwoven fabric and PVC sheets, thermoplastic elastomer (TPE) sheets, and single sheets of high-density polyethylene sheets (HDPE), and these can be appropriately selected and used. It is preferable that the sheet thickness is about 1.5 to 3.0 mm, taking into account elongation due to settlement, etc.

In this embodiment, a polyethylene terephthalate (PET) nonwoven fabric (500 g/ ^m2 ) is used for the protective mat 22. The waterproof sheet 20 is sandwiched between two protective mats 22 to form the surface waterproof work 10. Other suitable materials for the protective mat 22 include polyethylene (PE) and polypropylene (PP), but the protective mat 22 may be used on only one side of the waterproof sheet 20 depending on the on-site conditions in contact with each side of the waterproof sheet.

Here, the configuration of the end of the waterproof structure 1 of the present invention will be described with reference to Figures 2 and 3. The surface waterproofing work 10 of the general part is composed of a three-layer integrated laminated sheet in which both sides of the waterproof sheet 20 are sandwiched between protective mats 22, but at the end that is fixed to the base position of the caisson 4, as shown in Figure 2, the lower protective mat 22L and the waterproof sheet 20 are laid on the crushed stone 7, and an asphalt mastic footing layer 30 is formed on the waterproof sheet 20. This asphalt mastic footing layer 30 is a block body constructed by filling asphalt mastic between the holding concrete block 33 installed on the slope side and the caisson 4, and between this asphalt mastic footing layer 30 and the holding concrete block 33, a rising waterproof sheet 21 that is joined to the upper surface of the waterproof sheet 20 at the middle position in the width direction and functions as an intermediate waterproof sheet is provided so as to be sandwiched in close contact with the rising protective mat 23 between the asphalt mastic footing layer 30 and the holding concrete block 33. By adding a rising waterproof sheet 21 to this boundary portion, a specified seepage path length is ensured at the end of the surface waterproofing work 10, ensuring waterproofing at this boundary portion.

The rising waterproof sheet 21 is a waterproof sheet with the same thickness and specifications as the general waterproof sheet 20, which is welded and joined while maintaining its waterproofness so that it branches out upward from the upper surface of the waterproof sheet 20 laid on the top surface of the rubble mound 3. A rising protective mat 23 is attached to the outer surface of this rising waterproof sheet 21 (the side opposite the asphalt mastic foot protection layer 30) by folding up the end of the protective mat 22 on the upper surface side of the general part and extending it.

Conventionally, when setting the bottom width D of the asphalt mastic foot protection layer 30, in order to ensure water impermeability between the waterproof sheet 20 and the asphalt mastic foot protection layer 30, it is necessary to ensure a seepage path length L (for example, 1,250 mm = necessary contact length 500 mm x safety factor 2.5) equivalent to the bottom width D in a normal structure. However, in the present invention, since the rising waterproof sheet 21 is joined to the waterproof sheet 20 while maintaining water impermeability, the height H of the rising waterproof sheet 21 is added as the seepage path length to obtain the seepage path length L: L = D + H
It can be considered as:
Therefore, even if there are limitations on the dimensions of the top surface of the rubble mound 3 and the required infiltration path length L cannot be secured with the bottom width D of the asphalt mastic foot protection layer 30, the water-tight specifications at the end of the water-tight work can be secured.

Figure 3 shows an enlarged view of the waterproof structure at the boundary 6a (hereinafter referred to as the embedment boundary 6a) between the upper end of the embedded part of the steel sheet pile 6 on the back side of the waterproof revetment 1 shown in Figure 15 and the ground surface. As shown in Figure 3, the tip of the steel sheet pile 6 is embedded in the deep mixed treated soil (C.D.M.) 2 that was constructed as a waterproof base, but the inside of the waterproof revetment 1 between the steel sheet pile 6 and the surface of the mixed treated soil 2 on both sides of the reclaimed area 11 are poured with underwater non-separable concrete 36 for unevenness correction, making the surface almost flat, and furthermore, an asphalt mastic adhesion layer 35 with a thickness of about 15 cm is formed on the concrete surface, ensuring waterproofing at the embedment boundary 6a of the steel sheet pile 6.

On the surface of the asphalt mastic adhesive layer 35 inside the waterproof revetment 1, the ends of the waterproof sheet 20 and upper protective mat 22U of the surface waterproof work 10 laid on the rubble mound 3 are extended to the embedment boundary 6a position of the steel sheet pile 6, and a foot-fixing asphalt mastic foot-fixing layer 30 is formed over a predetermined range of the end of the upper protective mat 22U. Meanwhile, an outer vertical waterproof work 27 is provided on the side of the steel sheet pile 6 facing the landfill area 11. In the outer vertical waterproof work 27, a three-layer integrated laminated sheet is used in which the waterproof sheet 20 is sandwiched between the protective mats 20, just like the surface waterproof work 10 of the rubble mound 3.

A three-layered laminated sheet is also formed on the foundation surface over a predetermined range from the steel sheet pile 6 on the reclaimed area 11 side. The waterproofing performance of the base of the outer vertical waterproofing 27 of the steel sheet pile 6 and the end of the foundation surface waterproofing 15 is ensured by the asphalt mastic footing layer 30 filled in the area partitioned by the holding concrete block 33, as shown in Figure 3. At this time, in the foundation surface waterproofing 15, the rising waterproof sheet 21 and the rising protective mat 23 joined to the upper surface of the waterproof sheet 20 having the same configuration as that shown in Figure 2 are provided in close contact with the side of the asphalt mastic footing layer 30 and the holding concrete block 33. The infiltration path length of this foundation surface waterproofing 15 can also be the sum of the sheet lengths of the waterproof sheet 20 and the rising waterproof sheet 21 of the foundation surface waterproofing 15. As a result, waterproofing is also ensured in the foundation surface waterproofing 15 at the embedment boundary 6a of the steel sheet pile 6.

4 shows a modified example of the rising waterproof sheet 21 joined to the waterproof sheet 20 of the surface waterproof work 10 at the top of the rubble mound 3. As shown in the figure, in the asphalt mastic foot protection layer 30 formed in the area partitioned by the back side base of the caisson 4 at the top of the rubble mound 3 and the holding concrete block 33, a rising waterproof sheet 21A as a first intermediate waterproof sheet is provided between the holding concrete block 33 and the asphalt mastic foot protection layer 30, and a rising waterproof sheet 21B as a second intermediate waterproof sheet having a height (length) 1/2 that of the rising waterproof sheet 21A is provided at the approximate center position in the width direction of the asphalt mastic foot protection layer 30 , and the waterproof sheet 20 and these two rising waterproof sheets 21A and 21B are used to extend the seepage path length. By arranging the two rising waterproof sheets 21A, 21B so as to rise vertically from the waterproof sheet 20 of the surface waterproof work 10, the seepage path length L at the end of the surface waterproof work 10 is the sum of the lengths of these waterproof sheets 20 , 21A , 21B , as shown by the dashed line in Figure 4. In other words, if the bottom width of the asphalt mastic foot protection layer 30 is D and the height is H,
L=D+H+(H/2)+(H/2)
This allows the waterproofing performance of the asphalt mastic foot protection layer 30 to be more effectively exhibited. In this embodiment, the length of the rising waterproof sheet 21B is half that of the rising waterproof sheet 21A , but the length of the rising waterproof sheet 21B can be appropriately changed as long as the length is short enough to enable the rising waterproof sheet 21B to be embedded in the asphalt mastic foot protection layer 30 and to be supported independently.

Each figure in Figure 5 shows a modified example in which the number of rising waterproof sheets 21B is increased to three or five and joined to the waterproof sheet 20 of the surface waterproofing work 10 in an asphalt mastic foot protection layer 30 having the same structure as in Figure 4. In these modified examples, the height of each sheet required to ensure the required adhesion length (seepage path length) can be reduced by increasing the number of rising waterproof sheets 21B, so it is also possible to reduce the amount of asphalt mastic filling by lowering the height H of the asphalt mastic foot protection layer 30.

Figure 6 shows a waterproof revetment 1, similar to the example of a sea surface disposal site shown in Figure 15, with the interior partitioned by a caisson-type composite breakwater on the front side of the revetment and steel sheet piles 6 on the rear side, backfilled with solidification treated soil 9. The configuration of this example differs from that of the waterproof revetment 1 in Figure 15 in that an inner vertical waterproof structure 26 is provided over the entire surface of the inner side (solidification treated soil side) of the steel sheet piles 6 on the rear side. The waterproof structure of this waterproof revetment 1 is composed of a surface waterproof structure 10 and an inner vertical waterproof structure 26.

Figure 7 shows an enlarged view of the base of the inner vertical waterproofing work 26 of the steel sheet pile 6 of the waterproof revetment 1 shown in Figure 6 and the tip of the slope side of the surface waterproofing work 10. In this case, as in the case shown in Figure 3, the tip of the steel sheet pile 6 is embedded in the deep mixed treated soil 2 that has been constructed as a waterproof base, and underwater non-separable concrete 36 for uneven leveling is poured into the surface of the internal mixed treated soil, and an asphalt mastic adhesive layer 35 of a specified thickness is formed on the surface.

On the surface of the asphalt mastic adhesive layer 35, the tip of the waterproof sheet 20 of the surface waterproofing work 10 laid on the rubble mound 3 (Figure 6) is extended to the embedment boundary 6a of the steel sheet pile 6, and in order to ensure waterproofing of this tip, an asphalt mastic foot protection layer 30 is formed in a specified area partitioned by a retaining concrete block 33 installed on the protective mat 22. At this time, an inner vertical waterproofing work 26 consisting of a three-layer integrated laminated sheet is applied to the inner side surface of the steel sheet pile 6.

At the base of the inner vertical waterproofing work 26 and the tip of the surface waterproofing work 10 at the embedment boundary 6a of the steel sheet pile 6, as in the configuration shown in FIG. 3, a rising waterproofing sheet 21 and a rising protective mat 23 are provided between the asphalt mastic footing layer 30 and the holding concrete block 33 so as to rise along the side of the asphalt mastic footing layer 30 and the holding concrete block 33. This allows waterproofing to be maintained between the inner vertical waterproofing work 26 and the surface waterproofing work 10. When the inner vertical waterproofing work 26 shown in FIG. 6 is adopted, there is an advantage that it is not affected by the step with the mixed treated soil layer 2 caused by the future settlement of the existing ground 12 located outside the mixed treated soil layer 2, compared to the case of the outer vertical waterproofing work 27 shown in FIG. 3.

[Configuration of the waterproof structure in vertical waterproof construction]
Figure 8 shows an embodiment in which a waterproof structure for a seawall at a marine disposal site, as another invention , is applied to a divided portion 15 of a waterproof sheet 20 attached as an outer vertical waterproof structure 27 (71) of steel sheet piles of a waterproof seawall at a marine disposal site of a similar scale to the marine disposal site illustrated in Figures 15 and 16, and to a caisson side fixed portion 4A as a waterproof seawall.

As shown in Figure 8 and supplementary Figures 15 and 16, caissons 4 (64) are installed on rubble mounds 53 constructed on deep mixed treated soil layers 52 as structures on the front side (ocean side) of the waterproof revetment 1 that defines the landfill area 11 (62) that will be the sea surface disposal site. The caissons 4 (64) are made of known reinforced concrete boxes filled with filler sand (not shown), and multiple identical caissons 4 are installed in a row (L-shaped in Figure 8) on the rubble mound 53 (Figure 15), functioning as structures on the front side of the waterproof revetment 1 that defines the landfill area 11 (62) of a specified area and width in the coastal waters.

On the other hand, as a structure on the rear side of the water-resistant revetment 1, a steel sheet pile 6 (56) is erected at a position that ensures a certain distance from the caisson 4, whose rear side is backed with solidified treated soil 9 (59), so as to form an impermeable wall. The top of the steel sheet pile 6 (56) is supported by a tie rod T, which uses the caisson 4 (64) on the front side as a retaining structure. An outer vertical water-resistant structure 27 (71) is provided on the outer surface of the steel sheet pile 6 (on the reclaimed area 11 (62) side) so as to cover the entire surface.

(Configuration of waterproof structure at sheet end in waterproof sheet divided portion)
As shown in Figure 8, the laminated waterproof sheet 20 of the outer vertical waterproof structure 27 (71) has a different construction period for each work section, so it is attached in a divided state to the steel sheet pile 6 (56) at the boundary between each work section (hereinafter referred to as the dividing section 15). The configuration of the waterproof structure of the sheet end of the waterproof sheet of the present invention at this dividing section 15 will be described below. Below, the symbols in parentheses will be omitted.

Figure 9 is an enlarged view showing one embodiment of the waterproofing structure of the present invention at the separation section 15 (Figure 8-IX) of the outer vertical waterproofing work 27. The figure shows a plan view of the end of a laminated waterproofing sheet 20 attached along the outer surface of a steel sheet pile 6 and separated at the boundary of the construction area. As shown in the figure, the end of the three-layer laminated waterproofing sheet 20 has a two-layer waterproofing sheet consisting of a protective sheet 22 and a waterproofing sheet 21, excluding the protective sheet 22 on one side, attached to the surface of the steel sheet pile 6. In addition, a waterproofing sheet 25 (hereinafter referred to as a branched waterproofing sheet 25) is added, extending laterally in a branched shape from the bent part of the steel sheet pile 6. This branched waterproof sheet 25 is a two-layer waterproof sheet consisting of a protective sheet 22 and a waterproof sheet 21, which have the same thickness and specifications as the waterproof sheet 21. The base of the waterproof sheet 25 is welded and joined to the surface of the waterproof sheet 21 so that it branches out at the bend between the waterproof sheet 21 and the steel sheet pile 6, and is extended to a specified range within the dividing section 15, thereby ensuring a sufficient seepage path length within the dividing section 15.

As shown in Figure 9, the branched waterproof sheet 25 is arranged in a straight line that is approximately symmetrical with respect to the dividing section 15 (the boundary between the adjacent construction sections) with the branched waterproof sheet 25 attached to the waterproof sheet 21 constructed in the adjacent construction section. Furthermore, as shown in the figure, the landfill area 11 (Figure 8) side of the steel sheet pile 6 on which the waterproof sheet end 21a and the branched waterproof sheet 25 are arranged is covered with a cover plate 31, forming a space of a specified volume (hereinafter referred to as the dividing section space 38).

As shown in Figure 9, the cover plate 31 is a processed steel plate with flanges 31b bent into a crank shape on both sides of the plate body 31a. The cover plate 31 covers the separation section 15 using the position of the bolt 32, the head of which has been attached in advance to a predetermined position on the steel sheet pile 6 side by welding or the like, as a guide, and the cover plate 31 can be attached to the predetermined position by tightening the nut on the bolt 32 emerging from the through hole in the flange 31b.

Furthermore, as shown in Figure 9, the separation space 38 surrounded by the steel sheet pile 6 and the cover plate 31 is filled with asphalt mastic As that is filled in a molten state and then cooled and solidified, and the waterproof sheet end 21a and the branch waterproof sheet 25 are completely buried in contact with the asphalt mastic As. This ensures that the infiltration path length of each waterproof sheet end of the adjacent work sections located in the separation section 15 is sufficient, and the waterproofing of the waterproof sheet at the separation section 15 is ensured.

Figures 10(a) to (d) are partial enlarged views showing modified examples of the branched waterproof sheet 25. The branched waterproof sheet 25 shown in Figure 9 has a shape that extends linearly from the surface of the waterproof sheet 21, but various modified examples can be adopted to extend the seepage path length at the waterproof sheet end 21a by the branched waterproof sheet 25, i.e., to improve the waterproof performance. For example, Figure 10(a) shows an example in which a flange 25a is provided at the tip of the branched waterproof sheet 25 to make the whole T-shaped. By welding or integrally molding a sheet piece equivalent to the flange 25a at the tip of the branched waterproof sheet 25 to make the tip shape T-shaped or L-shaped, the seepage path length at the tip of the branched waterproof sheet 25 can be extended. Figure 10(b) shows a modified example in which a resin round rod-shaped body 25b is integrally molded at the tip of the branched waterproof sheet 25. Figures (c) and (d) show examples in which second and third branched waterproof sheets 25B and 25C, which have short sheet lengths, are provided in multiple locations on the waterproof sheet 21. In these examples, the permeation path length of the second and third branched waterproof sheets 25B and 25C is added to the permeation path length along the first branched waterproof sheet 25A, so a more sufficient permeation path length can be ensured.

Figure 11 shows another embodiment of the waterproof structure of the seawall of the sea surface disposal site. As shown in the figure, in this embodiment, two long connecting bolts 32 that connect and fix the cover plate 35 and the steel sheet pile 6 are welded to the inner surface of the steel sheet pile 6 in the separation space 38. By inserting the tips of these connecting bolts 32 into connecting holes (not shown) in the flat cover plate 35, the positioning and fixing of the cover plate 35 can be performed simply and accurately. In addition, both ends 35a of the cover plate 35 can reliably press and hold the waterproof sheet 21 extending from both sides of the separation section 15.

(Configuration of the water-proof structure of the sheet end at the caisson side fixing part)
12 shows an embodiment of the waterproof structure of the waterproof sheet end 21a at the anchoring part (hereinafter, referred to as the caisson side anchoring part 4A) in the caisson 4 of the outer vertical waterproof structure 27 of the steel sheet pile 6 shown in FIG. 8. In the caisson side anchoring part 4A, it is necessary to securely attach the waterproof sheet end 21a to the caisson surface 4a to sufficiently secure the seepage path length of the waterproof sheet end 21a. For this purpose, an anchoring part space 40 is secured in the part where the waterproof sheet end 21a is anchored to the caisson surface 4a, and the seepage path length is extended by providing a branch waterproof sheet 25 extending from the waterproof sheet side to the anchoring part space 40. At this time, one side of the anchoring part space 40 is covered with a cover plate 41. The cover plate 41 is L-shaped with a flange 41a at the end, and is fixed and held to the caisson surface 4a by an anchor bolt 42 at the position of the flange 41a. The other end of the cover plate 41 is fastened to the steel sheet pile 6 by bolts 43 so as to sandwich the waterproof sheet end 21a and to be in close contact with the steel sheet pile 6. At this time, rubber packing 44 or the like is attached to the mounting positions of the bolts 42, 43 to improve watertightness. Furthermore, the anchoring space 40 is filled with molten asphalt mastic As, forming a reliable waterproof structure at the caisson side anchoring part 4A of the waterproof sheet end 21a.

Figure 13 shows another embodiment in which the fixing end of the waterproof sheet end 21a is positioned within the fixing space 40 in the caisson side fixing portion 4A. As shown in the figure, in this embodiment, the fixing space 40 is partitioned by the steel sheet pile 6 and the cover plate 45 that covers the open side of the steel sheet pile 6. The cover plate 45 has a substantially Z-shaped cross section with a right angle at the bent portion in a plan view, and rib plates 45a are attached to each bent portion at both ends of the plate at a predetermined interval in the longitudinal direction (depth direction), maintaining the right angle shape of the bent portion. The root portion 45b of the cover plate 45 is fixed and held to the caisson surface 4a by the anchor bolt 46. The waterproof sheet end 21a extended from the general portion to the fixing space 40 is extended to the caisson surface 4a along the inner surface of the steel sheet pile 6 in the fixing space 40, and is fixed to the caisson surface 4a by the anchor pin 47. In addition, a branched waterproof sheet 25 for extending the seepage path length is welded near the sheet end 21a along the caisson surface 4a. Asphalt mastic As is also filled into the anchoring space 40 and cooled and solidified, forming a reliable waterproof structure at the caisson side anchoring part 4A of the waterproof sheet end 21a.

Figure 14 shows another embodiment in which the fixed end of the waterproof sheet end 21a in the caisson side fixing section 4A is located in the fixing section space 40 surrounded by the caisson surface 4a and a steel sheet pile 6C as a fixing end cover. As shown in the figure, the fixing section space 40 is partitioned by the caisson surface 4a and a steel sheet pile 6C fixed to the caisson surface 4a along the height direction of the caisson with a fixing metal fitting (not shown). In addition, an asphalt block 48 is sandwiched between the caisson surface 4a and the end of the steel sheet pile 6C to improve adhesion, and the gap between the caisson surface 4a and the steel sheet pile 6C is blocked to maintain waterproofing.

On the other hand, the waterproof sheet end 21a extending from the general part to the anchoring space 40 is further stretched along the surface of the gap adjustment plate 49 and the caisson surface 4a, and the tip part is led into the anchoring space 40 from one end of the steel sheet pile 6C. The root part 49a of the gap adjustment plate 49 is fixed to the caisson surface 4a by the anchor bolt 46. The waterproof sheet end 21a extends along the caisson surface 4a in the anchoring space 40 and extends a predetermined length along the inner surface of the steel sheet pile 6C. In addition, at the end position of the steel sheet pile 6C, a branch waterproof sheet 25 for extending the seepage path length is welded to the surface of the waterproof sheet end 21a. In addition, asphalt mastic As is filled in the anchoring space 40, and in a cooled and solidified state, a reliable waterproof structure is formed at the caisson side anchoring part 4A of the waterproof sheet end 21a.

As described above, in each embodiment of the present invention, the molten asphalt mastic is densely filled in the space partitioned by the holding concrete block 33 as a partition formwork material installed at a predetermined position on the waterproof sheet 20 of the asphalt mastic layer of each base, the space surrounded by the upper surface of the waterproof sheet 20 and the side of the rising waterproof sheet 21, and the dividing space 38, the fixing space 40, or the space surrounded by the end 21a of the waterproof sheet 21 and the side of the branching waterproof sheet 25, and the waterproofing is ensured in each part by cooling and solidifying while retaining its function as a viscoelastic body. In addition, instead of asphalt mastic as a water-impermeable filling waterproofing material, various asphalt-based mixtures that can be expected to have the same handling properties and waterproofing properties during use, as well as concrete-based materials, soil-based materials, chemical-based materials, etc. can also be used.

In the above description, the present invention is not limited to the various embodiments, and various modifications are possible within the scope of the claims. In other words, the technical scope of the present invention also includes embodiments obtained by combining technical means that are appropriately modified within the scope of the claims.

Reference Signs List 1: Sea surface disposal site 2: Mixed treated soil layer 3: Rubble mound 4: Caisson 4A: Caisson side anchoring portion 6, 6C: Steel sheet pile 10: Surface waterproofing work 11: Reclaimed land area 15: Base surface waterproofing work 20: Waterproof sheet 22: Protective mat 22U: Upper protective mat 22L: Lower protective mat 25: Branched waterproof sheet 26: Inner vertical waterproofing work 27: Outer vertical waterproofing work 30: Separation space 30: Asphalt mastic foot fixing layer 33: Holding concrete block 35: Asphalt mastic adhesion layer 38: Separation space 31, 35, 41, 45: Cover plate 40: Anchorage space As: Asphalt mastic

Claims (5)

A waterproof structure in which an end of a waterproof sheet constituting a waterproof layer laid on a waterproof base surface supporting a revetment structure is fixed to a base of the revetment structure constructed to divide a sea surface disposal site revetment, via a foot-blocking waterproof layer formed by filling the foot-blocking waterproof layer with an impermeable waterproof material, the end of the waterproof sheet constituting the waterproof layer being laid on a waterproof base surface supporting the revetment structure,
The foot-proofing waterproof layer is composed of a cooled and solidified asphalt mastic foot-proofing layer filled in a space between a holding work provided on the waterproof sheet and the revetment structure,
The waterproof sheet is laid so that an end portion thereof extends to the base of the revetment structure, and a first intermediate waterproof sheet is welded and joined to the waterproof sheet so that the first intermediate waterproof sheet is in close contact between the foot protection waterproof layer on the waterproof sheet and the supporting work, and the shape of the first intermediate waterproof sheet raised from the waterproof sheet is maintained.
In addition to the first intermediate waterproof sheet, at least one second intermediate waterproof sheet is welded and joined to the waterproof sheet between the first intermediate waterproof sheet and the revetment structure so as to be held in a shape raised from the waterproof sheet within the foot protection waterproof layer;
A waterproof structure for a seawall at a sea surface disposal site, characterized in that the seepage path length between the surface of the foot-proofing waterproof layer and the waterproof sheet is extended via the surfaces of the first intermediate waterproof sheet and the second intermediate waterproof sheet . The waterproof structure of a seawall at a marine disposal site as described in claim 1 , wherein the second intermediate waterproof sheet has a length shorter than that of the first intermediate waterproof sheet and is buried within the root reinforcement waterproof layer to maintain its erected shape. 3. The waterproof structure for a seawall at a sea surface disposal site according to claim 2 , wherein the length of the second intermediate waterproof sheet is half the length of the first intermediate waterproof sheet. 2. The waterproof structure for a seawall at a sea surface disposal site according to claim 1, wherein the waterproof layer is made of a laminated sheet of the waterproof sheet and protective mats sandwiching both sides of the waterproof sheet. The waterproof structure of a sea surface disposal site revetment according to claim 1, wherein the impermeable waterproof material is selected from asphalt-based materials, concrete-based materials, soil-based materials, and chemical-based materials that have a predetermined waterproofing performance.

Images