JP5038074B2 - Damage detection system and damage detection method for water shielding sheet - Google Patents

Description

  The present invention relates to a breakage detection system and breakage detection method for a seepage control sheet, and more particularly, to prevent damage to a protection seepage sheet laid over an upper part of the contaminated soil in order to contain contaminated soil containing waste in the ground. The present invention relates to a breakage detection system and a breakage detection method for a water shielding sheet that manage presence / absence and prevent contaminants from leaking outside.

  In the ground where contaminated soil containing waste such as a waste disposal site is buried in the ground, for example, a shield laid on the bottom of the waste disposal site can be used to prevent the contaminated soil from adversely affecting the surrounding environment. Various techniques have been proposed to enable detection of breakage of the water sheet or to prevent sewage from leaking to the surrounding ground when breakage of the water shielding sheet laid on the bottom surface is detected (for example, , Patent Document 1 and Patent Document 2).

  In addition, in the ground where contaminated soil containing waste such as a waste disposal site is buried in the ground, if the ground surface is to be used effectively as, for example, a park or other facility, it will be caused by the contaminated soil buried in the ground. As measures to prevent the impact from occurring, for example, by removing contaminated soil and replacing it with soil that has not been contaminated, or by surrounding the contaminated soil with water-proof ground or members and sealing it, Containment methods that prevent substances from leaking to the outside are conceivable. However, the replacement method is a large-scale construction, and costs are enormous, so the containment method is often adopted.

In the containment method, the bottom of the contaminated soil is covered with, for example, a water-impermeable layer and a water-impervious sheet, and the side of the contaminated soil is covered with a vertical water-impervious wall and a water-impervious sheet made of steel sheet piles that are driven into the impermeable layer, for example. After covering the top of the soil with a water-impervious sheet, by forming a protective soil layer above the upper water-impervious sheet, the ground surface by this protective soil layer can be used effectively, for example, as a park or other facility It becomes possible to do.
JP-A-6-63526 Japanese Patent Laid-Open No. 10-15517

  However, when the ground surface of the ground where the contaminated soil is buried in the ground by the containment method is to be used effectively as a park, etc., if the water shielding sheet covering the upper part of the contaminated soil is damaged, for example, it is poured onto the ground surface. Rainwater or the like may flow into the contaminated soil from the damaged part, and the contaminated water may flow out through the damaged part, affecting the surrounding environment. For this reason, it is necessary to periodically check whether or not the water shielding sheet is damaged, and it is also necessary to check whether or not the water shielding sheet is damaged even when an earthquake occurs.

  On the other hand, the water-impervious sheet covering the upper part of the contaminated soil is not in a state where the water pressure due to the contaminated water inside the contaminated soil is always loaded, so that the water-impervious sheet laid on the bottom of the contaminated soil is not shielded. It is not always necessary to carefully manage the water sheet for damage. Therefore, the conventional breakage detection system and breakage detection method described in Patent Document 1, Patent Document 2 and the like developed for the water-impervious sheet laid at the bottom are laid so as to cover the upper part of the contaminated soil. Applying the water-impervious sheet increases the cost as well as the equipment. For this reason, it is desired to develop a new breakage detection system and breakage detection method that can check the presence or absence of breakage of the water shielding sheet laid over the top of the contaminated soil with a simpler configuration. Yes.

  The present invention has been made paying attention to such a conventional problem, and it is possible to check the breakage of the water shielding sheet that can check whether or not the water shielding sheet laid to cover the upper part of the contaminated soil has a simple configuration. It is an object to provide a system and a damage detection method.

In order to contain the contaminated soil containing waste in the ground, a protective water shielding sheet is laid over the contaminated soil, and a protective soil layer made of a permeable earth and sand material is formed above the protective water shielding sheet. And used in a ground preparation area where the ground surface by the protective soil layer can be effectively used, and is used to control the presence or absence of breakage of the protective water shielding sheet to prevent contaminants from leaking out from the contaminated soil. A water sheet breakage detection system, wherein the protective water-impervious sheet is laid with a drainage gradient, and a portion of the protective soil layer is blocked by a water-impervious wall standing from the protective water-impervious sheet. In the upstream part of each block , a water level observation hole made of a perforated pipe is provided, which is embedded in the protective soil layer with the upper end opening surface opened to the ground surface and erected. , Downstream part A water passage hole is formed in a lower end portion of the water shielding wall, and a block through pipe to which an open / close valve is attached is formed in the water passage hole, and an outer peripheral surface of the block through pipe is an opening edge of the water passage hole. In a state of being watertightly joined to the part, it is disposed across the downstream part of the upstream block and the upstream part of the downstream block, and the water passage hole is closed for each block. The water is stored in each block by supplying the water with the water level, and the water level of the stored water does not decrease for a predetermined time, so that it can be confirmed that the protective water shielding sheet of each block is not damaged , When the confirmation in each block is over , the above object is achieved by providing a water blocking sheet breakage detection system that opens the water passage hole and allows the stored water to flow down to the downstream block. Achieved.

  And according to the breakage detection system for a water-impervious sheet of the present invention, it is preferable that the protective water-impervious sheet is laid with the upper and lower surfaces covered with an upper layer nonwoven fabric and a lower layer nonwoven fabric.

  Moreover, according to the water-blocking sheet breakage detection system of the present invention, the water-blocking wall is preferably formed using a sheet material configured by covering both surfaces of the water-blocking sheet with a nonwoven fabric.

  Furthermore, according to the system for detecting breakage of a water shielding sheet of the present invention, the protective water shielding sheet is laid on the upper surface of a basic crushed stone layer spread above the contaminated soil so as to have a predetermined gradient. Is preferred.

Furthermore, according to the system for detecting breakage of a water shielding sheet of the present invention, the opening / closing valve is attached to a portion disposed in the block on the downstream side of the block penetrating pipe, and is opened / closed on the downstream side of the water shielding wall. It is preferable that a valve is provided and the water passage hole is opened and closed by opening and closing the opening and closing valve.

Further, according to the water-blocking sheet breakage detection system of the present invention, the block through pipe is a perforated pipe, and a portion between the water-blocking wall in which the water-flow hole is formed and the open / close valve. However, it is preferable that it is a non-porous part with which the small hole of the surrounding surface was obstruct | occluded .

And this invention is a water-blocking sheet breakage detection method using the water-blocking sheet breakage detection system, wherein each block is supplied with water with the water passages closed, water was stored in a block, that the water level of the stored water is not reduced a predetermined time, being adapted confirmatory testing to a protective water barrier sheet of the blocks is not corrupted, water upstream block After the confirmation inspection in the upstream block is completed, the water passage hole is opened and the stored water is transferred to the downstream block. By flowing down and storing water while supplying and replenishing water appropriately in the downstream block, it is confirmed from the upstream block to the downstream block by performing a check inspection that the protective impermeable sheet is not damaged. Towards By providing a breakage detection method of seepage control sheet sequentially verify that the block protect water shield sheet is not damaged, it is obtained by achieving the above object.

  According to the breakage detection system and breakage detection method of the water shielding sheet of the present invention, it is possible to check whether the water shielding sheet laid covering the upper part of the contaminated soil is broken or not with a simple configuration.

  As shown in FIG. 1, the system for detecting breakage of a water shielding sheet according to a preferred embodiment of the present invention has an area of about 3 to 4 ha that is conventionally used as a waste disposal site, for example, a ground preparation area. As shown in FIG. 2 and FIG. 3, as shown in FIG. 2 and FIG. 3, the contaminated soil 11 containing waste is confined in the ground, and the protective soil layer 12 is formed above the contaminated soil 11, thereby forming the ground by the protective soil layer 12. For example, when the surface 12a is effectively used as a park, the presence or absence of damage to the protective water shielding sheet 13 laid over the top of the contaminated soil 11 is detected, and the contaminated water inside the contaminated soil 11 passes through the damaged portion. It was adopted in order to avoid effectively affecting the surrounding environment by flowing out.

  In other words, in the present embodiment, the ground formation area 10 is such that the bottom of the contaminated soil 11 containing the input waste is covered with, for example, an impermeable layer (not shown), and the side of the contaminated soil 11 is, for example, The impermeable layer is driven with a penetration length of 2.5 m or more, and the joint portion is covered with a vertical water-impervious wall 14 made of a steel sheet pile filled with a swellable waterproofing material made of polyurethane resin. Moreover, in this embodiment, the whole is covered with the impermeable layer, the vertical impermeable wall 14, and the protective impermeable sheet 13 by covering the upper part of the contaminated soil 11 and laying the protective impermeable sheet 13. Contaminated soil 11 is contained in the ground. The breakage detection system for the impermeable sheet according to the present embodiment is capable of efficiently checking the presence or absence of breakage of the protective impermeable sheet 13 laid over the contaminated soil 11 with a simple configuration. It is. In the present embodiment, the upper end portion of the vertical impermeable wall 14 and the protective impermeable sheet 13 are joined to each other in a watertight manner by, for example, a bolt connection 35 with a bulk concrete 34 interposed therebetween (FIG. 2).

  And the breakage detection system of the impermeable sheet of this embodiment covers and protects the upper part of this contaminated soil 11 in order to contain the contaminated soil containing a waste in the underground 11, as shown in FIGS. A ground formation area in which a water-impervious sheet 13 is laid and a protective soil layer 12 made of a water-permeable earth and sand material is formed above the protective water-impervious sheet 13 so that the ground surface 12a can be effectively used. 10 is a damage detection system that manages the presence or absence of breakage of the protective impermeable sheet 13 to prevent the contaminant from leaking out from the contaminated soil 11, and the protective impermeable sheet 13 has a drainage gradient X. The protective soil layer 12 is divided into a plurality of blocks 16 by a water shielding wall 15 erected from the protective water shielding sheet 13, and a water level observation hole is formed in an upstream portion of each block 16. 7 and a water passage hole 18 is provided at the lower end portion of the water shielding wall 15 in the downstream portion so as to be openable and closable, and water is supplied to each block 16 with the water passage hole 18 closed. Water is stored in each block 16, and the level of the stored water does not decrease for a predetermined time so that it can be confirmed that the protective water shielding sheet 13 of each block 16 is not damaged.

  Moreover, in this embodiment, the protective water-impervious sheet 13 is laid in a state where the upper and lower surfaces are covered with the upper-layer nonwoven fabric 19a and the lower-layer nonwoven fabric 19b (see FIG. 5). The sheet material 22 is formed by covering both surfaces of the substrate 20 with a nonwoven fabric 21 (see FIG. 4).

  Further, in the present embodiment, the block through pipe 29 is inserted into the water passage hole 18, and an open / close valve 30 is provided on the downstream side of the water shielding wall 15 in connection with the block through pipe 29. By opening and closing, the water passage hole 18 is opened and closed.

  In this embodiment, the protective water-impervious sheet 13 is known as a water-impervious sheet laid in a waste disposal site, and is made of, for example, a soft synthetic resin-based or rubber-based sheet material, for example, 1.0 to 2.0 mm. A protective sheet of a certain thickness can be used. More specifically, for example, a sheet material made of polypropylene and having a thickness of about 1.5 mm can be preferably used. Moreover, since it is difficult to cover the entire ground formation area 10 with a single sheet material, the protective impermeable sheet 13 has a unit impermeable sheet of a predetermined size suitable for construction at the laying work site. For example, it is laid so as to have a drainage gradient X having an inclination of, for example, about 1% while the end portions are overlapped and joined together by thermal welding or pressure bonding via an adhesive.

  Here, in the present embodiment, the ground formation area 10 is divided into a first drainage area 24a, with a ridge portion 23 (see FIG. 1) provided so as to cross the central portion of the ground formation area 10, The second drainage area 24b is divided into two. In the first drainage area 24 a, a drainage gradient X is provided toward the southwest corner of the ground formation area 10, and in the second drainage area 24 b, the drainage gradient is directed toward the northeast corner of the ground formation area 10. X is provided. Further, the water in the protective soil layer 12 that has flowed down due to the drainage gradient X of each drainage area 24a, 24b is, for example, the block 16 ′ at the most downstream part in the southwest corner or the northeast corner of the ground formation area 10, for example. It flows into the rainwater drainage culvert 25 provided outside the ground formation area 10 through the connecting pipe 36 formed by extending the block through pipe 29 provided on the downstream side (see FIG. 2). The inflowing water flows down toward the rainwater storage facility 26 provided on the south side or the north side of the ground formation area 10 through the rainwater drainage culvert 25 (see FIG. 1).

  Moreover, in this embodiment, the protective water-impervious sheet 13 is laid along the upper surface of the basic crushed stone layer 27 spread above the contaminated soil 11 so as to have a predetermined gradient of, for example, about 1%. Thus (see FIGS. 2 and 3), a drainage gradient X is provided. That is, in this embodiment, the basic crushed stone layer 27 is provided above the contaminated soil 11 with a thickness of, for example, about 150 to 300 mm, and is flat with a predetermined gradient using a bulldozer or other various compactors. It is possible to easily form a compact rolling surface as a laying surface of the protective impermeable sheet 13. This also makes it possible to easily give a predetermined drainage gradient X to the protective water-impervious sheet 13 laid along the upper surface of the basic crushed stone layer 27.

  Further, in the present embodiment, a pore water pressure control pipe 28 is provided in the basic crushed stone layer 27 in a lower layer portion close to the contaminated soil 11. The pore water pressure control pipe 28 is made of, for example, a perforated pipe made of thick polyvinyl chloride having a diameter of about 100 mm, and is arranged to have a gradient similar to the drainage gradient X of the protective water shielding sheet 13. The pore water pressure control pipe 28 functions as a drainage facility when, for example, the groundwater inside the contaminated soil 11 rises, and appropriately allows the water inside the contaminated soil 11 to flow in. The inflowing water can be discharged to the rainwater drainage culvert 25 via the pore water pressure control pipe 28 (see FIG. 2). In addition, the provision of the pore water pressure control pipe 28 can effectively prevent liquefaction of the contaminated soil 11 during an earthquake or the like.

  As described above, the protective impermeable sheet 13 laid along the upper surface of the basic crushed stone layer 27 is made of, for example, polypropylene sheet material, and the upper and lower surfaces are covered with the upper layer nonwoven fabric 19a and the lower layer nonwoven fabric 19b. Laid. Here, as the upper layer nonwoven fabric 19a and the lower layer nonwoven fabric 19b, for example, various known nonwoven fabrics used for civil engineering can be used, and each of them is provided with a thickness of about 10 mm, for example. The upper and lower nonwoven fabrics 19a and 19b cover the upper and lower surfaces of the protective water-impervious sheet 13, so that the protective water-impervious sheet 13 is effectively protected. It becomes possible to avoid that 13 breaks.

  Moreover, when it is judged by the breakage detection system of this embodiment that a breakage location exists in the protective water-impervious sheet 13, various known flows from the water level observation hole 17, for example, using the upper layer nonwoven fabric 19 a and the lower layer nonwoven fabric 19 b as a base material. It is possible to repair a damaged portion without excavating the protective soil layer 12 by injecting an injection-solidifying material excellent in properties as a restoration material and infiltrating the upper-layer nonwoven fabric 19a and the lower-layer nonwoven fabric 19b. In addition, the upper layer nonwoven fabric 19a and the lower layer nonwoven fabric 19b can be joined together in advance to the protective water shielding sheet 13 and laid along the upper surface of the basic crushed stone layer 27 together with the protective water shielding sheet 13.

  The protective soil layer 12 formed above the protective water-impervious sheet 13 is, for example, about 500 mm by laying and rolling sandy soil or gravelly soil as a water-permeable earth and sand material by various known methods. Built with a thickness of. In the present embodiment, the surface of the protective soil layer 12 has a gradient similar to the drainage gradient X of the protective impermeable sheet 13 and has a substantially constant thickness over substantially the entire ground formation area 10. It is formed. Further, in the protective soil layer 12, a water shielding wall 15 that divides the first drainage area 24a and the second drainage area 24b into a plurality of blocks 16, a water level observation hole 17, a block through pipe 29, an opening / closing valve 30, and the like are embedded. Is done.

  In the present embodiment, the water shielding wall 15 is formed using a sheet material 22 configured by covering both surfaces of the water shielding sheet 20 with the nonwoven fabric 21. The water-impervious sheet 20 is formed using the same protective sheet as the protective impermeable sheet 13, for example, made of polypropylene and having a thickness of about 1.5 mm. Moreover, similarly to the protective water-impervious sheet 13, the sheet material 22 is constructed in which the nonwoven fabric 21 is integrally bonded to both surfaces in advance. The sheet material 22 is protected, for example, in a state where the water-impervious sheet 20 is joined to the protective impermeable sheet 13 in a water-tight manner and in a state of being water-tightly joined to the water-impervious sheet 20 of the other impermeable wall 15 intersecting at the corners of the block 16 By standing up to a height of about 450 mm from the water-impervious sheet 13, the water-impervious wall 15 surrounding the four sides of each block 16 is formed. Further, the impermeable wall 15 made of the sheet material 22 is buried in the protective soil layer 12 with a covering thickness of about 50 mm remaining between the ground surface 12a.

As a result, the first drainage area 24a and the second drainage area 24b of the ground formation area 10 are partitioned and arranged vertically and horizontally by the impermeable wall 15, for example, the length of one side is about 30 m and the area is about 1000 m ^2. It is divided into a plurality of blocks 16 of the size.

  The water level observation hole 17 provided in the upstream side portion of each block 16 is made of, for example, a perforated tube made of thick polyvinyl chloride having a diameter of about 100 mm, and the lower end opening surface is placed on the protective water shielding sheet 13 and protected. The upper end opening surface is opened to the ground surface 12a through the soil layer 12, and is embedded in the protective soil layer 12 in a standing state. Water can be appropriately injected into the protective soil layer 12 of each block 16 through the water level observation hole 17. In addition, the water level inside the water level observation hole 17 is observed so that the change in the water level in the protective soil layer 12 of each block 16 can be grasped. Furthermore, as described above, when it is determined that there is a damaged portion in the protective impermeable sheet 13, an injection solidified material having excellent fluidity is applied to the upper nonwoven fabric 19a and the lower nonwoven fabric 19b through the water level observation hole 17. It can be injected. An open / close lid 31 is detachably attached to the upper end opening surface of the water level observation hole 17.

  The block through pipe 29 inserted through the water passage hole 18 formed in the water shielding wall 15 in the downstream portion of each block 16 is made of a perforated pipe made of thick polyvinyl chloride having a diameter of about 100 mm, for example. The block penetration pipe 29 straddles the downstream portion of the upstream block 16 and the upstream portion of the downstream block 16 in a state where the outer peripheral surface of the block penetration tube 29 is watertightly joined to the opening edge of the water hole 18. Arranged. Further, the block penetration pipe 29 is disposed to protrude from the upstream block 16 with a length of about 300 mm, for example, and is installed along the upper surface of the protective impermeable sheet 13 with a length of about 800 mm as a whole.

  An opening / closing valve 30 is attached to a portion of the block penetrating pipe 29 downstream of the block 16 so that the water passage hole 18 can be appropriately opened / closed by opening / closing the opening / closing valve 30. It has become. In the block through pipe 29, a portion between the water shielding wall 15 in which the water passage hole 18 is formed and the on-off valve 30 is a non-hole portion 29a in which a small hole on the peripheral surface is closed. Thus, when the opening / closing valve 30 is closed, the water stored in the upstream block 16 does not flow into the downstream block 16 through the small hole on the peripheral surface of the block through pipe 29. .

  In the present embodiment, the pore water pressure control pipe 28, the water level observation hole 17, and the block through pipe 29 made of a perforated pipe are underground with their outer peripheral surfaces covered with a filter material (not shown). By embedding in, it is possible to effectively prevent clogging of small holes on the peripheral surface.

  As the opening / closing valve 30 connected to the block through pipe 29 and provided on the downstream side of the water shielding wall 15, various known valve devices used by being attached to a water pipe or the like can be used. The on-off valve 30 is connected to the block through pipe 29 in the downstream block 16 with the water shielding wall 15 interposed therebetween. Further, the opening / closing valve 30 has a lower end opening surface placed on the protective impermeable sheet 13 and also passes through the protective soil layer 12 and the upper end opening surface is opened in the ground surface 12a inside a manhole 33 provided. In the accommodated state, it is embedded in the protective soil layer 12. An opening / closing lid 32 is detachably attached to the upper end opening surface of the manhole 33.

  And in the breakage detection system of the impermeable sheet of this embodiment provided with the above-mentioned structure, it can confirm easily that the protection impermeable sheet 13 is not damaged with the following detection methods. That is, for each block 16, water is supplied with the water passage hole 18 closed to store the water in each block 16, and the water level of the stored water elapses for a predetermined time of, for example, several hours to half a day. As a result, it is possible to reliably confirm that the protective water shielding sheet of each block is not damaged.

  Moreover, in this embodiment, in each drainage area 24a, 24b, the water block is stored in the upstream block 16, and a confirmation inspection is performed to confirm that the protective impermeable sheet 13 is not damaged. When the confirmation inspection is finished, the water stored by opening the water passage hole 18 by opening / closing the opening / closing valve 30 is caused to flow down to the downstream block 16, and water is supplied and replenished appropriately in the downstream block 16. Can be stored and a confirmation test can be performed to confirm that the protective water-impervious sheet 13 is not damaged. As a result, it is possible to sequentially and efficiently confirm that the protective water-impervious sheet 13 of each block 16 is not damaged from the upstream block 16 toward the downstream block.

  Thus, according to the present embodiment, it is possible to easily and reliably check the presence or absence of breakage of the protective water shielding sheet 13 laid so as to cover the upper portion of the contaminated soil 11 with a simple configuration.

The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, it is not always necessary to supply water to each block through the water level observation hole, and it can also be performed directly from the ground surface of the protective soil layer. Further, it is not always necessary to form the water-impervious wall by using a sheet material formed by covering both surfaces of the water-impervious sheet with a nonwoven fabric. Can be partitioned.

1 is a schematic plan view for explaining a ground formation area in which a water shielding sheet breakage detection system according to a preferred embodiment of the present invention is employed. It is a schematic sectional drawing explaining the structure of the breakage detection system of the impermeable sheet which concerns on preferable one Embodiment of this invention. It is a schematic sectional drawing explaining the structure of the breakage detection system of the impermeable sheet which concerns on preferable one Embodiment of this invention. It is sectional drawing in alignment with AA of FIG. 3 explaining the structure of the breakage detection system of the impermeable sheet which concerns on preferable one Embodiment of this invention. It is a partial expanded sectional view explaining the layer structure of the part by which the protective water-impervious sheet was laid.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ground preparation area 11 Contaminated soil 12 Protective soil layer 12a Ground surface 13 by protective soil layer Protective water shielding sheet 14 Vertical water shielding wall 15 Water shielding wall 16 Block 17 Water level observation hole 18 Water flow hole 19a Upper layer nonwoven fabric 19b Lower layer nonwoven fabric 20 Shielding Water sheet 21 Non-woven fabric 22 Sheet material 23 Ridge portion 24a First drainage area 24b Second drainage area 25 Rainwater drainage culvert 26 Rainwater storage facility 27 Basic crushed stone layer 28 Pore water pressure control pipe 29 Block penetration pipe 29a Non-porous portion 30 of the block penetration pipe Open / close valve X Drain gradient

Claims (7)

In order to contain the contaminated soil containing waste in the ground, a protective water shielding sheet is laid over the contaminated soil, and a protective soil layer made of a permeable earth and sand material is formed above the protective water shielding sheet. And used in a ground preparation area where the ground surface by the protective soil layer can be effectively used, and is used to control the presence or absence of breakage of the protective water shielding sheet to prevent contaminants from leaking out from the contaminated soil. A water sheet breakage detection system,
The protective impermeable sheet is laid with a drainage gradient, and the part of the protective soil layer is partitioned into a plurality of blocks by a impermeable wall standing from the protective impermeable sheet,
The upstream part of each block is provided with a water level observation hole made of a perforated pipe that is embedded in the protective soil layer with the upper end opening surface opened to the ground surface, and the downstream part. A water passage hole is formed in the lower end portion of the water shielding wall.
In the water passage hole, a block through pipe to which an open / close valve is attached is connected to the downstream portion of the upstream block in a state where the outer peripheral surface thereof is watertightly joined to the opening edge of the water passage hole, It is arranged across the upstream part of the side block,
For each block, water is supplied in a state in which the water passage hole is closed and water is stored in each block, and the water level of the stored water does not decrease for a predetermined time. A water-blocking sheet that allows confirmation that each block is not damaged, and allows the stored water to flow down to the downstream block by opening the water passage hole after confirmation in each block. Damage detection system.   The water-blocking sheet breakage detection system according to claim 1, wherein the protective water-blocking sheet is laid in a state where upper and lower surfaces are covered with an upper layer nonwoven fabric and a lower layer nonwoven fabric.   The water-impervious sheet breakage detection system according to claim 1, wherein the water-impervious wall is formed using a sheet material configured by covering both surfaces of the water-impervious sheet with a nonwoven fabric. The protective water barrier sheet, the water shield sheet according to claim 1 which is laid on the upper surface of the upper to spread smoothed basal crushed stone layer of contaminated soil so as to have a predetermined gradient Damage detection system. The opening / closing valve is attached to a portion of the block penetrating pipe that is disposed on the downstream block, and the opening / closing valve is provided on the downstream side of the water-impervious wall. water shield sheet breakage detection system according to any one of claims 1 to 4, holes are opened and closed. The block through pipe is a perforated pipe, and a portion between the water shielding wall in which the water passage hole is formed and the open / close valve is a non-hole portion in which a small hole on the peripheral surface is closed. The breakage detection system for a water shielding sheet according to claim 5 . A breakage detection method water shield sheet using water-barrier sheet breakage detection system according to any one of claims 1 to 6, water wherein for each block, in a state of closing the water flow hole To store water in each block, and the water level of the stored water does not decrease for a predetermined time, so that the protective water shielding sheet of each block is not damaged and inspected .
Water is stored in the upstream block and a confirmation inspection is performed to confirm that the protective impermeable sheet is not damaged. After the confirmation inspection in the upstream block is completed, the water stored by opening the water passage hole is stored. The upstream block is made to flow down to the downstream block, the water is stored while replenishing water appropriately in the downstream block, and the protective block is not damaged. A method for detecting breakage of a water shielding sheet that sequentially confirms that the protective water shielding sheet of each block is not broken toward the downstream block .

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