JP5691110B2 - Rehabilitation method of existing impermeable sheet - Google Patents

Description

The present invention relates to the repair how the existing water barrier sheet.

Conventionally, in a so-called storage section such as a dam, a reservoir, an industrial waste disposal site or the like, a non-permeable sheet made of a synthetic resin called a water-impervious sheet is laid to prevent water permeation to the original ground. Although such a water shielding sheet can prevent water permeation to the original ground for a long period of time, it needs to be repaired every predetermined period.
Synthetic resin impermeable sheets that are currently undergoing renovation are often vinyl chloride impermeable sheets, but in recent years, polyethylene impermeable sheets have been widely used as higher performance impermeable sheets. For this reason, polyethylene water shielding sheets are also used as the water shielding sheets for repair. However, polyethylene is difficult to bond with vinyl chloride, has extremely low work efficiency, and has many disadvantages in terms of water shielding reliability and construction cost at the joint.

  By the way, some prior arts (for example, Patent Documents 1 and 2) have been proposed as a method for laying an existing water shielding sheet. However, in any case, the waterproof sheet to be bonded is manufactured from the same material, and there is no disclosure of a technique for bonding the waterproof sheets manufactured from different materials.

Japanese Patent Laid-Open No. 08-229530 Japanese Patent Laid-Open No. 09-210836

The present invention provides an existing impermeable sheet that can be quickly and reliably subjected to a joining process when joining a currently used polyethylene impermeable sheet to an existing vinyl chloride impermeable sheet. It is intended to provide a renovation how.

In order to solve the above problems, the present inventor has intensively studied, and as a result, has come up with the following configuration.
That is, a method of repairing an existing water-impervious sheet made of vinyl chloride laid in order to prevent water from penetrating from the reservoir to the original ground, the existing impermeable sheet remaining in a part of the original ground A step of removing in a state of being made, a first water-impervious sheet made of vinyl chloride and a second water-impervious sheet made of polyethylene, and the first water-impervious sheet and the second water-impervious sheet The edge of the first water-impervious sheet or the second water-impervious sheet that is formed in the overlapping joint part that is joined in a state where the edge parts overlap each other over the required width range, and is exposed at the overlapping joint part. An intermediate bonding water-impervious sheet to which a silicone sheet covering a required range including a portion is bonded, and the edge portion of the first water-impervious sheet, which is one end edge of the intermediate bonding sheet , Remains in a part of the ground And a step of compression bonding the edge portion of the water shield sheet, the edges of the repair for polyethylene water shield sheet edge portion of the second water shield sheet as the other end edge of the water shield sheet the mediation junction And a step of laying a repair-made polyethylene water-impervious sheet on the original ground by crimping and joining the parts.

Moreover, it is preferable that the overlap joint part of the said water shielding sheet for mediation joining is joined by the mechanical joining means, and this mechanical joining means is the said 1st water shielding sheet and the said 2nd water shielding. It is preferable that the fasteners are attached to end edges of the sheet. It is more preferable to use a hook-and-loop fastener as the fastener.
These make it easy to temporarily bond the first water-proof sheet made of vinyl chloride and the second water-proof sheet made of polyethylene when manufacturing a water-proof sheet for mediation bonding in factories, etc., and a sheet made of silicone Workability at the time of bonding is improved. That is, since a water-shielding sheet for mediation joining that ensures high joint reliability can be obtained at low cost, the existing water-impervious sheet can be repaired at low cost.

In addition, the intermediate water-impervious sheet overlaps the second water-impervious sheet on one surface side of the first water-impervious sheet, and polyethylene on the other surface side of the first water-impervious sheet. Ltd. third water shield sheet has is duplicated in the first, the second, overlapping portions of the third water barrier sheet, the second and the third polyethylene water shield sheet is melted It is preferable to use a water shielding sheet for mediation bonding formed by thermocompression bonding at a temperature. Thereby, the joining process of the 1st water shielding sheet in a duplication junction part, and the 2nd and 3rd water shielding sheet can be performed easily.

Further, filling the first have the overlapping singular to the position of the joint portion or a plurality of through holes in the water shield sheet is formed, the second and the third polyethylene said through hole molten the water shield sheets It is preferable to use the water-impermeable sheet for mediation joining. As a result, the bonding strength between the first water-impervious sheet and the second and third water-impervious sheets at the overlapping joint is greatly increased, and the handling and joining workability of the water-impervious sheet for intermediate joining are greatly improved. To do.

  Moreover, after joining the 1st water shielding sheet of the said some water shielding sheet for mediation joining along the edge of the water shielding sheet left in a part of the said storage part, the said water shielding sheet for mediation joining adjacent to it The sheet preferably further includes a step of joining the same materials to each other. As a result, the construction efficiency can be improved and the construction cost can be reduced because construction can be performed using the water shielding sheet for intermediate joining formed in a dimension with good handling properties even in a wide range of repair sites.

According to refurbishment how the existing water shield sheet according to the present invention, in a time of joining the polyethylene water shield sheet water shield sheet vinyl chloride of the existing, necessary to perform a bonding process of different members each other on site work Therefore, it is possible to perform a quick and reliable joining process, and it is possible to perform construction with high reliability at a low cost.

It is a top view of the water shielding sheet for mediation joining concerning a 1st embodiment. It is sectional drawing in the AA line in FIG. It is a top view which shows the state before repair of the impermeable sheet of a dam. It is a top view which shows the state which left a part of the existing water-impervious sheet of a dam. It is a top view which shows the state which joined the impermeable sheet for mediation joining to the existing existing impermeable sheet. It is a top view which shows the state after the repair work of the impermeable sheet of a dam. It is sectional drawing of the water shielding sheet for mediation joining concerning 2nd Embodiment. It is sectional drawing of the water shielding sheet for mediation joining concerning 3rd Embodiment. It is a top view of the water shielding sheet for mediation joining concerning a 4th embodiment. It is sectional drawing in the BB line in FIG. It is a top view which shows the water shielding sheet for mediation joining concerning 5th Embodiment. It is sectional drawing which shows an example of deformation | transformation embodiment of a duplication junction part. It is sectional drawing which shows an example of deformation | transformation embodiment of a duplication junction part.

  Hereinafter, an embodiment of a water-impervious sheet for mediation joining 10 used for repair work of a water-impervious sheet made of vinyl chloride and a method for repairing an existing water-impervious sheet will be described with reference to the drawings.

(First embodiment)
As shown in FIG. 1 and FIG. 2, the intermediary bonding water-proof sheet 10 according to the present embodiment includes a first water-proof sheet 20 made of vinyl chloride and a second water-proof sheet 30 made of polyethylene over a required width range. It is joined via the adhesive 40 in the overlapped state. In the overlapping joint portion between the first water shielding sheet 20 and the second water shielding sheet 30, the overlapping joint portion side of the second water shielding sheet 30 exposed on the surface of the storage portion that contacts the water. A silicone sheet 50 is bonded to the required range across the edge 32 by an adhesive 40. As the adhesive 40 described above, for example, Dow Corning SE930 sealant manufactured by Toray can be suitably used.
In this way, the joint portion (here, the overlapping joint portion side edge 32 of the second water shielding sheet 30) exposed to the side in contact with the stored water in the intermediary joint water shielding sheet 10 is the silicone sheet 50. The coating increases the water tightness, thereby imparting a very high water tightness to the intermediary bonding water shielding sheet 10.

Since these first water-impervious sheet 20, second water-impervious sheet 30, adhesive 40, and silicone sheet 50 can use known products, detailed descriptions thereof are omitted here. .
According to the impermeable sheet 10 for mediation joining of this embodiment, the work efficiency in the renovation work of the existing impermeable sheet in the dam that is a storage part as shown in FIGS. 3 to 6 can be greatly improved. This is advantageous in that it is possible to improve the bonding strength and water density reliability at the joint between the repaired portion and the existing portion of the water sheet. Below, the repair method of the existing impermeable sheet in the dam using the impermeable sheet for mediation joining concerning this embodiment is demonstrated.

In order to prevent the stored water W from penetrating into the original ground G on the bottom surface of the water storage section on the upstream side of the dam body DB of the dam D, a water shielding sheet SS is provided on the surface of the original ground G as shown in FIG. May be laid. Conventionally, such a water shielding sheet SS was mostly made of vinyl chloride, but in recent years, a higher performance polyethylene water shielding sheet (polyethylene water shielding sheet for repair) PS is provided. It became so. Therefore, a renovation work for sequentially replacing the existing water-impervious sheet SS in the dam D with a polyethylene water-impervious sheet PS is performed.
In the normal dam D, the position of the drainage opening provided in the levee body DB or the like may be higher than the bottom surface position of the water storage part, so construction after discharging all the stored water W from the water storage area is impossible. There is a case. In such a case, as shown in FIG. 4, since a part of the stored water W remains in the water storage region, the water shielding sheet SS is left in a state where a part of the existing water shielding sheet SS remains in the water storage region. Renovation work is required. 5 and 6, illustration of the stored water W is omitted for convenience of explanation.

  By the way, the bonding between vinyl chloride and polyethylene requires high-precision bonding work, and it is possible to directly connect the existing water shielding sheet SS made of vinyl chloride and the polyethylene water shielding sheet PS for repair at the repair work site. Joining is extremely difficult. Further, the period during which the amount of water stored in the dam D can be brought into a state as shown in FIG. 4 is extremely short, and prompt repair work is required. For this reason, the water-impermeable sheet 10 for intermediary joining according to the present embodiment manufactured in advance in a factory or the like so that the polyethylene-made water-impervious sheet PS for repair can be easily joined to the existing water-impervious sheet SS made of vinyl chloride. Is convenient.

Specifically, as shown in FIG. 5, the end edge portions of the first water shielding sheet 20, which is one end edge of the intermediary bonding water shielding sheet 10, are connected to the edge portion of the existing water shielding sheet SS. After making it overlap by required width, it joins using a welding apparatus. Since this joining process is a process for joining vinyl chlorides, it is possible to perform highly reliable processing of overlapping joints even in field work.
After joining the edge part of the existing water-impervious sheet SS made of vinyl chloride and the edge part of the first water-impervious sheet 20 made of vinyl chloride, the water-tightness of the overlapping joint part is maintained as necessary. Sealing may be performed. Such a sealing process can suitably use a silicone sheet 50 that is adhered to the intermediary bonding water shielding sheet 10.

Since the other end edge of the intermediary bonding water-impervious sheet 10 is formed in the second water-impervious sheet 30 made of polyethylene, a known welding device is used as the end edge of the polyethylene water-impervious sheet PS for repair. Can be joined together. Since this is also a welding process between polyethylenes, the reliability of the joining state in the overlapping joints is ensured even in the field work. A sealing process for keeping water-tightness may be applied to a welded joint portion between polyethylenes as necessary.
Thus, the joining process of the edge part of the 1st water shielding sheet 20 in the some water shielding sheet 10 for mediation joining along the extension direction of the edge part of the existing water shielding sheet SS made from vinyl chloride is carried out. Repeat. In addition, regarding the joining of the adjacent intermediary joining water-impervious sheets 10, 10,..., The joining process is performed between the edge portions of the same material, so that the construction can be performed without any difficulty.

  After joining the edge part of the 1st water shielding sheet in the intermediate | middle waterproofing sheet 10 with respect to all the edge parts of the existing water shielding sheet SS, the polyethylene in the intermediate | middle joining water shielding sheet 10 is made. It is only necessary to join the edge part of the polyethylene waterproof sheet PS for repair to the edge part of the second waterproof sheet 30. Moreover, the joining process of adjacent polyethylene water-impervious sheets PS can be performed easily and reliably, and the repair work of the water-impervious sheet is completed as shown in FIG. In addition, since the existing impermeable sheet SS will continue to be used in a state where it is not renovated, since the existing impermeable sheet SS is very little deteriorated since it is always underwater after the start of flooding of the dam D, Since the initial water shielding performance is maintained, it can be used continuously without any problems.

(Second Embodiment)
FIG. 7 is a cross-sectional view of the water-impermeable sheet for mediation joining according to the second embodiment. The cross-sectional position is the same position as in the first embodiment. In and after this embodiment, the same reference numerals used in the description of the first embodiment are used for the same configuration as the intermediary bonding water-impervious sheet 10 according to the first embodiment. Omitted.
In the overlapping joint portion between the first water shielding sheet 20 and the second water shielding sheet 30 in the intermediary joining water shielding sheet 10 according to the present embodiment, a pair of fasteners 60 are provided as mechanical joining means on the respective overlapping surfaces. , 60 is a feature. These fasteners 60, 60 can be attached by sewing the fastener attachment pieces 61, 61 to the overlapping surfaces of the first water shielding sheet 20 and the second water shielding sheet 30. A known fastener can be used as the fastener 60, and a waterproof fastener is particularly preferably used.

  In the present embodiment, the overlapping portion of the first water shielding sheet 20 and the second water shielding sheet 30 is mechanically joined by the fastener 60. When adhering the silicone sheet 50 to the surface of the overlapping joint in the intermediary joining water-impervious sheet 10, as shown in FIG. 7, the adhesive 40 is applied to a range including the fastener 60 portion. It is preferable to keep it.

(Third embodiment)
FIG. 8 is a cross-sectional view of the water-impermeable sheet for mediation joining according to the third embodiment. The cross-sectional position is the same position as in the first embodiment.
A pair of hook-and-loop fasteners 62 and 62 are attached to the overlapping surfaces of the overlapping portions of the first water-proof sheet 20 and the second water-proof sheet 30 in the intermediary bonding water-proof sheet 10 according to the present embodiment. This is a feature. These hook-and-loop fasteners 62 and 62 can be attached to the overlapping surface of the first water-impervious sheet 20 and the second water-impervious sheet 30 by sewing or bonding. Adhesive 40 may be used when the silicone sheet 50 is adhered to the surface of the joining portion in the intermediary joining water-impervious sheet 10, and when the engagement between the hook-and-loop fasteners 62 and 62 is not disturbed, The adhesive 40 may also be applied to the engaging portion of the surface fastener 62.

(Fourth embodiment)
FIG. 9 is a plan view of the water-impermeable sheet for mediation joining according to the fourth embodiment. 10 is a cross-sectional view taken along line BB in FIG.
In the overlapping joining portion of the intermediary joining water-impervious sheet 10 according to the present embodiment, the second water-impervious sheet 30 is overlapped on one surface (upper surface) of the first water-impervious sheet 20, and the first water-impervious sheet. The third water-impervious sheet 34 is overlapped with the other surface (lower surface) of 20. Further, at a position spaced the required distance from the overlap joint side edge 22 of the first water shield sheet 20 that the through-hole 24 is formed is characteristic.

One end edge of the third water-impervious sheet 34 made of polyethylene is attached to the lower surface side of the second water-impervious sheet 30 by a known method such as welding or adhesion at a position away from the overlapping joint side end edge 32. It has been. Moreover, the other end (overlap | joining junction side edge) of the 3rd water-impervious sheet 34 is a free end. The thickness dimension of the third water shielding sheet 34 is preferably equal to or greater than the thickness dimension of the second water shielding sheet 30.
In this way, by attaching the third water-impervious sheet 34 to the second water-impervious sheet 30, the insertion portion 36 can be formed at a site that becomes an overlapping joint with the first water-impervious sheet 20. The separation distance between the inner surfaces of the second water-impervious sheet 30 and the third water-impervious sheet 34 (insertion part 36) is formed to be at least the thickness dimension of the first water-impervious sheet 20.

  In the intermediary joining water-impervious sheet 10 formed in this way, the joining of the edge part of the first water-impervious sheet 20 and the edge part of the second water-impervious sheet 30 is first performed by the insertion part 36. The inner space is filled with the adhesive 40, and then the overlapping joint side edge 22 of the first water shielding sheet 20 is inserted into the insertion portion 36 filled with the adhesive 40. And what is necessary is just to perform a crimping | compression-bonding process in the state which clamped the 1st water-impervious sheet 20 with the 2nd water-impervious sheet 30 and the 3rd water-impervious sheet 34 using the crimping | compression-bonding apparatus which is not shown in figure.

  When this crimping process is performed, heat treatment is performed so that the polyethylene melts, so that the second water shielding sheet 30 and the third water shielding sheet 34 are melted, and the first molten water shielding sheet 30 is in an unmelted state. The molten polyethylene is filled in the through holes 24 formed in the water sheet 20. Since the melting temperature of vinyl chloride is higher than the melting temperature of polyethylene, the thermocompression treatment can be performed at a temperature at which only polyethylene is melted.

At this time, if the plate thickness dimension of the third water-impervious sheet 34 is sufficiently thick, even if the melted polyethylene is filled in the through-hole 24, the thickness dimension of the overlapping joint portion is reduced (the second dimension). This is convenient because the thickness of the water shielding sheet 30 is not reduced. The third water-impervious sheet 34 may only increase the plate thickness dimension only for the portion to be subjected to the thermal welding process.
Thereafter, if the portion subjected to the pressure bonding treatment is cooled, the overlapping joint portion between the first water shielding sheet 20, the second water shielding sheet 30, and the third water shielding sheet 34 is removed at the through hole 24 portion. becomes stopped state, each water shield sheets 20, 30 can be firmly integrated 34. Finally, the adhesive 40 may be used to cover the required range including the overlapping joint side edge 32 of the second water shielding sheet 30 with the silicone sheet 50.

(Fifth embodiment)
FIG. 11: is a top view of the water shielding sheet for mediation joining concerning 5th Embodiment. This embodiment is a modification of the fourth embodiment. In the fourth embodiment, the through hole 24 formed in the first water barrier sheet 20 is formed in a position spaced the required distance from the overlap joint side edge 22 of the first water shield sheet 20 However, in this embodiment, the through-holes 24 are formed in an array that communicates with the overlapping joint-side edge 22 of the first water-impervious sheet 20. As shown in FIG. 11, the through-hole 24 is formed in a state where it communicates with the overlapping joint portion side edge 22 of the first water shielding sheet 20 via the communication portion 26. The width dimension of the through hole 24 and the communication part 26 in the extending direction of the overlapping joint side edge 22 of the first water shielding sheet 20 is narrower than the width dimension of the through hole 24. It is formed to become.

  By adopting such a shape of the through hole 24, the molten polyethylene resin generated when the first, second, and third water shielding sheets 20, 30, and 34 are thermocompression bonded is formed in the through hole 24 and the communication portion. However, since the melted polyethylene is filled from both the through hole 24 and the communication portion 26, the filling efficiency is better than that of the fourth embodiment, and a more reliable joining process is performed. It is advantageous in that it becomes possible.

  About the concrete repair method of the water shielding sheet using the water shielding sheet 10 for mediation joining described in the second to fifth embodiments, it can be performed in the same manner as the method described in the first embodiment. Therefore, detailed description here is omitted.

  As mentioned above, based on embodiment, although the water shielding sheet 10 for mediation joining concerning this invention was demonstrated in detail, it cannot be overemphasized that the technical scope in this invention is limited to the above embodiment. For example, the water shielding sheet 10 for mediation bonding in the embodiment described above is formed in a panel shape having a predetermined dimension that is convenient for transportation by a truck or the like as shown in FIG. 1 or FIG. It may be formed.

Moreover, in 1st-5th embodiment, all adhere | attach the sheet | seat 50 made from silicone so that the required range including the duplication junction side edge 32 of the 2nd water-impervious sheet 30 may be covered in an overlap junction. Although the form bonded with the agent 40 is described, it is not limited to this embodiment. In any of the embodiments, as shown in FIG. 12, the silicone sheet 50 is bonded to the overlapping joint so as to cover a required range including the overlapping edge portion 22 of the first water shielding sheet 20. The form bonded at 40 may be adopted.
Moreover, in 2nd-5th embodiment, although the adhesive agent 40 is apply | coated to the duplication junction part of the 1st water-impervious sheet 20 and the 2nd water-impervious sheet 30, the joining by the fastener 60, a surface fastener In the case where the bonding by 62, and the pressure bonding between the first water shielding sheet 20, the second water shielding sheet 30, and the third water shielding sheet 34 have sufficient strength, an adhesive is applied to the overlapping joint. 40 may not be applied.

Furthermore, in 4th Embodiment, although the 1st water-impervious sheet 20 is demonstrated about the structure by which multiple through-holes 24 are arrange | positioned at the required space | interval, the sheet | seat impermeable sheet 10 for mediation joining is demonstrated. The form which forms the elongated through-hole 24 in one place with respect to the 1st water shielding sheet 20 in can also be employ | adopted.
In the fourth and fifth embodiments, the third water-impervious sheet 34 is previously joined to the second water-impervious sheet 30 in the overlapping joint portion to form the insertion portion 36, and the adhesive 40 is applied to the insertion portion 36. After filling the insertion portion 36, the overlapping edge portion 22 of the first water shielding sheet 20 is inserted into the insertion portion 36, but the filling of the adhesive 40 to the insertion portion 36 is omitted. It is also possible to do.

  Furthermore, in 4th, 5th embodiment, although the 3rd water impervious sheet 34 is previously joined to the 2nd water impermeable sheet 30 in the overlap joint part, The two water-impervious sheets 30 and the third water-impervious sheet 34 may be made to overlap each other, and these may be collectively subjected to a thermocompression treatment. At this time, the adhesive 40 is not necessarily used. According to this joining treatment method, since the joining treatment of the first, second, and third water shielding sheets 20, 30, and 34 can be performed collectively, the intermediary joining water shielding sheet 10 is obtained at a lower cost. be able to.

  Furthermore, in the fourth and fifth embodiments, the through hole 24 is disposed in the first water shielding sheet 20 at the overlapping joint portion, but the through hole 24 is disposed as shown in FIG. Can be omitted. The cross-sectional position in FIG. 13 is a cross-sectional position on the line BB in FIG. The bonding of the third water-impervious sheet 34 and the thermocompression treatment at the overlapping bonded portion can be performed in the same manner as in the fourth and fifth embodiments. By adopting this form, it is possible to provide the water shielding sheet 10 for intermediate joining at a low cost by simplifying the formation of overlapping joints.

  In addition, as an application example of the intermediary bonding impermeable sheet 10 according to the present invention, the repair work of the existing impermeable sheet SS of the dam D has been described. Is not limited to the renovation of the existing water-impervious sheet SS of the dam D, but can also be applied to the renovation work of the water-impervious sheet laid in a storage part such as a reservoir or an industrial waste disposal site.

DESCRIPTION OF SYMBOLS 10 Water-impervious sheet 20 for repair 1st water-impervious sheet 22, 32 Overlap joint edge 24 Through hole 26 Communication part 30 Second water-impervious sheet 34 Third water-impervious sheet 36 Insertion part 40 Adhesive 50 Silicone Sheet 60 made of fasteners 61 Fastener mounting piece 62 Surface fastener D Dam DB Dike body G Original ground SS Existing water shielding sheet PS Polyethylene water shielding sheet W Reservoir

Claims (7)

A method for repairing an existing water-impervious sheet made of vinyl chloride laid to prevent water from penetrating from the reservoir to the ground,
Removing the existing impermeable sheet while remaining in a partial range of the original ground; and
A first water-impervious sheet made of vinyl chloride and a second water-impervious sheet made of polyethylene, and the edge portions of the first water-impervious sheet and the second water-impervious sheet span the required width range; Silicone which covers a required range including an edge portion of the first water shielding sheet or the second water shielding sheet which is formed in an overlapping joint portion joined in an overlapping state and exposed at the overlapping joint portion Using the water-impermeable sheet for mediation bonding to which the sheet made of the material is bonded, the edge portion of the first water-impervious sheet that is one end edge of the sheet for mediation-joining is left in a partial range of the original ground. The step of pressure bonding to the edge of the water-impervious sheet;
The polyethylene waterproof sheet for repair is produced by crimping and joining the edge part of the modified waterproof sheet made of polyethylene to the edge of the second waterproof sheet, which is the other edge of the intermediary bonding sheet . A process of laying on the ground,
A method for repairing an existing impermeable sheet, characterized by comprising:   The method for repairing an existing water-impervious sheet according to claim 1, wherein the overlapping joint portion of the intermediary joint water-impervious sheet is joined by mechanical joining means.   The method for repairing an existing waterproof sheet according to claim 2, wherein the mechanical joining means is a fastener.   The said fastener is a hook-and-loop fastener, The repair method of the existing impermeable sheet of Claim 3 characterized by the above-mentioned. In the intermediary impermeable sheet,
The second water-impervious sheet is overlapped on one surface side of the first water-impervious sheet, and the third water-impervious sheet made of polyethylene is overlapped on the other surface side of the first water-impervious sheet. Have been
It said first, said second, the overlapping portions of the third water barrier sheet, the second and the third intermediary bonding water-impervious sheet of polyethylene water shield sheet is formed by thermocompression bonding at a temperature at which melting of The method for repairing an existing water-impervious sheet according to claim 1, which is used. One or a plurality of through holes are formed at the position of the overlapping joint in the first water shielding sheet,
It said second and said third existing water shield sheet method renovation of claim 5, wherein the molten polyethylene water shield sheet which comprises using an intermediary bonding water shield sheet formed by filling in the through holes of. After joining the first water shielding sheets of the plurality of intermediate joining water shielding sheets along the edge of the water shielding sheet left in a part of the reservoir,
The adjacent impermeable sheet for intermediate bonding, further comprising a step of bonding the same materials to each other, wherein the existing impermeable sheet according to any one of claims 1 to 6 is characterized. Renovation method.

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