Water blocking sheet fixing method and water blocking sheet fixing structure

Abstract

To provide a water blocking sheet fixing method and a water block sheet fixing structure that can reduce waste in work and improve workability.SOLUTION: A water blocking sheet fixing method for fixing a water blocking sheet 7 on an inclined surface 5 in a cone-shaped waste disposal site 1 includes: a water blocking sheet laying process for laying the water blocking sheet 7 on the inclined surface 5 including the inside of a groove part 13, which is formed so as to be recessed downward in a small step part 11 in the middle of the inclined surface 5 or a flat portion 35 continued from the upper end of the inclined surface 5 to the outside; a temporarily holding process for installing a temporary weight 15 for holding the water blocking sheet 7 with the weight and temporarily fixing it on the water blocking sheet 7 inside the groove 13; and a concrete placing process for placing concrete in the groove 13 so as to bury the temporary weight 15.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a waterproof sheet fixing method and a waterproof sheet fixing structure. [Background technology]

[0002] Conventionally, a mortar-shaped waste disposal site is known (see, for example, Patent Document 1). In this type of waste disposal site, a mortar-shaped recess excavated in the ground constitutes a storage tank for storing waste. For example, in order to confine leachate generated in the storage tank due to rainfall or the like in the storage tank, a waterproof sheet, for example, is laid without gaps on the inner surface of the storage tank. In addition, a fixing concrete is provided in the middle or at the top of the slope. The fixing concrete holds down the waterproof sheet with its weight on the slope of the recess, fixing the waterproof sheet to the slope. During the construction of a waste disposal site, after the waterproof sheet is installed on the top surface of the excavated recess, there is a risk that the waterproof sheet will slip down before the fixing concrete is poured. As a countermeasure against this, for example, a method of placing a temporary weight on the location where the fixing concrete is to be installed to temporarily hold down the waterproof sheet is considered. Thereafter, when the fixing concrete is to be constructed, the temporary weight is removed, a formwork or the like is installed, and concrete is poured. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-299899 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned method involves the wasteful step of temporarily placing a temporary weight and then finally removing it, resulting in poor workability. The present invention aims to provide a waterproof sheet fixing method and waterproof sheet fixing structure that reduce wasteful work and improve workability. [Means for solving the problem]

[0005] The gist of the present invention lies in the following [1] to

[10] .

[0006] [1] A method for fixing a waterproof sheet to a sloping surface of a bowl-shaped waste disposal site, wherein a groove is formed in a small step part way down the slope or in a flat area extending from the upper end of the slope to the outside, so that the groove is recessed downward, and the method includes the steps of: laying a waterproof sheet on the slope including the inside of the groove; placing a temporary weight on the waterproof sheet in the groove to temporarily fix it by its weight; and pouring concrete into the groove to bury the temporary weight.

[0007] [2] A method for fixing a waterproof sheet described in [1], wherein the weight of each of the temporary weights is 60 kg or less.

[0008] [3] A method for fixing a waterproof sheet described in [1] or [2], wherein the peripheral corners of the underside of the temporary weight that comes into contact with the waterproof sheet during the temporary holding process are rounded or haunched.

[0009] [4] The waterproof sheet fixing method according to any one of [1] to [3], wherein in the concrete pouring step, the entire temporary weight is buried in the concrete.

[0010] [5] The method for fixing a waterproof sheet according to any one of [1] to [4], wherein the material of the temporary weight is concrete.

[0011] [6] The waterproof sheet fixing method described in any one of [1] to [5], wherein the material of the temporary weight is environmentally friendly concrete.

[0012] [7] The waterproof sheet fixing method according to any one of [1] to [6], wherein the concrete poured into the groove in the concrete pouring step is environmentally friendly concrete.

[0013] [8] A method for fixing a waterproof sheet described in any one of [1] to [7], wherein in the concrete pouring step, the groove into which the concrete has been poured is covered with a cover, and dry ice is placed inside the cover to subject the concrete to a carbonation curing treatment.

[0014] [9] A method for fixing a waterproof sheet described in any one of [1] to [8], wherein in the concrete pouring process, fresh concrete before being poured into the groove is mixed with dry ice in a concrete agitator.

[0015]

[10] A waterproof sheet fixing structure for fixing a waterproof sheet to the slope of a bowl-shaped waste disposal site, comprising: a groove formed so as to be recessed downward in a small step midway along the slope or in a flat area extending from the upper end of the slope to the outside; a waterproof sheet laid on the slope including the inside of the groove; a temporary weight placed on the waterproof sheet within the groove; and a concrete section poured into the groove with the temporary weight embedded therein. Effect of the Invention

[0016] According to the present invention, it is possible to provide a waterproof sheet fixing method and a waterproof sheet fixing structure that reduce wasteful work and improve workability. [Brief description of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of a waste disposal site to which a waterproof sheet fixing method and a waterproof sheet fixing structure according to an embodiment are applied. [Diagram 2] FIG. 2 is an enlarged cross-sectional view showing the vicinity of one of the step sections of a waste disposal site. [Diagram 3] 1 is a cross-sectional view showing the vicinity of a small step in the temporary holding step of a waterproof sheet fixing method. [Figure 4] A cross-sectional view showing an enlarged contact area between the temporary weight and the waterproof sheet. [Diagram 5]1 is a cross-sectional view showing the vicinity of a step portion during the concrete pouring process of the waterproof sheet fixing method. FIG. [Figure 6] FIG. 2 is a cross-sectional view showing the vicinity of a step portion during carbonation curing treatment in the waterproof sheet fixing method. [Figure 7] FIG. 11 is a cross-sectional view showing a waterproof sheet fixing structure according to a modified example. [Figure 8] 13(a) and 13(b) are plan views showing the inside of the groove in a temporary holding step of a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of a waterproof sheet fixing method and a waterproof sheet fixing structure according to the present invention will be described in detail with reference to the drawings. The waterproof sheet fixing method and the waterproof sheet fixing structure of the present embodiment are implemented during the construction of a waste disposal site 1 shown in FIG.

[0019] The waste disposal site 1 is a managed disposal site where waste is disposed of by landfill. Various wastes S, including organic matter and inorganic matter (salts, heavy metals), are dumped into the storage tank 3 of the waste disposal site 1 and disposed of by landfill. The storage tank 3 is shaped like a mortar, dug downward from the ground surface. As shown in FIG. 1, the waste disposal site 1 may also have a roof 4 that entirely covers the upper part of the storage tank 3. The wastes S include, for example, incineration ash and solidified fly ash generated in a waste incineration facility, organic sludge, inorganic sludge, wood chips, and slag. In this type of managed disposal site, water is sprayed into the storage tank 3 to stabilize the wastes S, and leachate is generated. This leachate is collected from the bottom 2 of the storage tank 3 through a water collection pipe (not shown) or the like and sent to a separate leachate treatment facility. The waste disposal site 1 is abandoned after the wastes S have been stabilized after the landfill is completed.

[0020] As described above, the storage tank 3 has a cone shape and has an inclined surface 5 that extends from the surrounding ground surface toward the bottom 2 of the storage tank 3. A waterproof sheet 7 that blocks water is laid without any gaps on the inner surface of the storage tank 3, including the bottom 2 and the inclined surface 5. The waterproof sheet 7 is, for example, a multi-layered sheet in which a plurality of waterproof layers and a plurality of protective mats are laminated. The waterproof layer is, for example, a polyethylene sheet having a thickness of about 1.5 mm, and the protective mat is, for example, a short-fiber nonwoven fabric having a thickness of about 4 to 10 mm. The waterproof sheet 7 confines the leachate within the storage tank 3 and does not leak into the ground 100.

[0021] A waterproof sheet fixing structure 30 (FIG. 5), which will be described later, is provided on the inclined surface 5 in order to fix the waterproof sheet 7. Note that the waterproof sheet fixing structure 30 is not shown in FIG. 1. This waterproof sheet fixing structure 30 prevents the waterproof sheet 7 from sliding down the inclined surface 5 due to the weight of the waste S dumped into the storage tank 3 or the weight of the waterproof sheet 7 itself. Furthermore, the waterproof sheet fixing structure 30 must not penetrate the waterproof sheet 7 so as not to impair the waterproofing properties of the waterproof sheet 7. Therefore, the waterproof sheet fixing structure 30 employs a structure in which the waterproof sheet 7 is pressed down from above by a gravitational force such as a fixing concrete 25 (FIG. 5), as will be described later.

[0022] A method for fixing the waterproof sheet 7 to the inclined surface 5 in the construction of the waste disposal site 1 and a waterproof sheet fixing structure 30 constructed by this fixing method will be described below. When constructing the waste disposal site 1, the ground 100 is excavated to form the storage tank 3 in the form of a cone-shaped recess. At this time, several (four in the example of FIG. 1) small steps 11 forming horizontal surfaces are formed in the middle of the inclined surface 5. The width of the small steps 11 is, for example, 1 m to 3 m. In some cases, a mortar layer (not shown) with a thickness of about 50 mm is sprayed onto the entire inner surface of the storage tank 3 after excavation.

[0023] Fig. 2 is an enlarged cross-sectional view showing the vicinity of one of the step portions 11. As shown in Fig. 2, a groove portion 13 is formed in the center of the step portion 11 so that the step portion 11 is dug down to form a recess. For example, the width of the groove portion 13 at the upper end is about 800 mm, and the depth of the groove portion 13 is about 400 mm. Note that the surface layer portion of the inclined surface 5, including the inner surface of the groove portion 13, may be formed of a mortar layer sprayed as described above, but this mortar layer is not shown in the drawings.

[0024] The method for fixing the waterproof sheet 7 in this embodiment includes a waterproof sheet laying step, a temporary holding step, and a concrete pouring step, which will be described below.

[0025] [Waterproof sheet laying process] In the waterproof sheet laying process, the waterproof sheet 7 is laid over the entire inner surface of the storage tank 3, including the inclined surface 5. At this time, the waterproof sheet 7 is installed so as to conform to the uneven shape of the entire upper surface of the inclined surface 5, including the upper surfaces of the step portions 11 on the inclined surface 5 and the inner surfaces of the groove portions 13.

[0026] [Temporary holding process] In the above state, there is a possibility that the waterproof sheet 7 will slide down the inclined surface 5 due to its own weight before the concrete pouring process described later is completed. Therefore, in order to prevent the waterproof sheet 7 from sliding down, a temporary weight is installed to hold down and temporarily fix the waterproof sheet 7. Specifically, as shown in FIG. 3, the temporary weight 15 is installed on the waterproof sheet 7 in the groove 13. The temporary weight 15 is an unreinforced precast concrete block, and has a size and shape that fits within the cross section of the groove 13. The temporary weight 15 has, for example, a substantially rectangular parallelepiped shape, and the size of the temporary weight 15 is, for example, about 20 cm x 20 cm x 30 cm. The upper end surface of the temporary weight 15 is located lower than the small step 11 that forms a horizontal plane. A commercially available precast concrete block such as a gutter block or a pedestrian / vehicle boundary block may be used as the temporary weight 15. The temporary weight 15 may be made of porous concrete as long as the necessary weight is ensured.

[0027] 4, the peripheral corner 15e (corner between the lower surface 15a and the side surface 15b) of the temporary weight 15 on the lower surface 15a that contacts the waterproof sheet 7 is rounded by, for example, R-chamfering. Note that the peripheral corner 15e may also be in the shape of a haunch by, for example, C-chamfering.

[0028] In this embodiment, one temporary weight 15 is heavy enough to be handled by one or two workers P. Therefore, there is no need to use a lifting device or the like for the installation work of the temporary weight 15. Here, for example, as shown in FIG. 3, the worker P manually installs the temporary weight 15. For example, the weight of one temporary weight 15 is 60 kg or less. If the weight of the temporary weight 15 is 60 kg or less, it can be carried by a maximum of two workers P, and it is possible to place it while being careful not to damage the waterproof sheet 7 during installation. Furthermore, it is more preferable that the weight of one temporary weight 15 is 30 kg or less. If the weight of the temporary weight 15 is 30 kg or less, it can be carried and placed as described above by one worker P. Note that FIG. 3 shows one cross section of the groove portion 13, but a plurality of temporary weights 15 similar to those in FIG. 3 are intermittently arranged at predetermined intervals in the extension direction of the groove portion 13 (the depth direction of the paper surface of FIG. 3). For example, the interval between the temporary weights 15 in the extending direction of the groove portion 13 is, for example, about 0.5 to 1 m.

[0029] [Concrete pouring process] Next, in the concrete pouring process, as shown in FIG. 5, concrete is poured into the groove 13 so as to bury the temporary weight 15. Specifically, a concrete agitator 21 and a concrete pump 23 are prepared outside the storage tank 3. Then, fresh concrete stirred by the concrete agitator 21 is sent to the groove 13 by the concrete pump 23 and poured into the groove 13. The fresh concrete is filled up to the upper end of the groove 13 (up to the height of the step 11) beyond the height of the upper end of the temporary weight 15, and the entire temporary weight 15 is completely buried in the fresh concrete in the groove 13. Thereafter, the fresh concrete in the groove 13 hardens to form a concrete section 17 in which the temporary weight 15 is buried. The upper end surface of the concrete section 17 is formed to be almost flush with the step 11. As a result, a fixed concrete 25 having the temporary weight 15 and the concrete section 17 is formed in the groove 13. The fixing concrete 25 is formed so as to fill the entire cross section of the groove 13, and its weight presses down the waterproof sheet 7 and fixes it onto the inclined surface 5. Note that the fixing concrete 25 does not require great strength, and therefore the concrete part 17 is unreinforced concrete that does not contain reinforcing bars, and there is no need to place reinforcing bars in the groove 13 during the concrete pouring process.

[0030] The waterproof sheet fixing structure 30 is constructed through the waterproof sheet laying step, temporary holding step, and concrete pouring step described above. As shown in Fig. 5, the waterproof sheet fixing structure 30 includes a groove portion 13 formed so as to be recessed downward in the step portion 11, a waterproof sheet 7 laid on the inclined surface 5 including the inside of the groove portion 13, a temporary weight 15 placed on the waterproof sheet 7 in the groove portion 13, and a concrete portion 17 poured in the groove portion 13 with the temporary weight 15 embedded therein.

[0031] Furthermore, in order to reduce the environmental impact associated with the construction of the waste disposal site 1, the material of the temporary weight 15 may be environmentally friendly concrete. The environmentally friendly concrete may be, for example, CO2 absorbing concrete that absorbs and fixes carbon dioxide, low-cement concrete in which part of the cement is replaced by blast furnace slag, fly ash, silica fume, light calcium carbonate, dried concrete sludge, or the like, concrete containing zeolite or the like as an alternative aggregate, concrete that has been subjected to forced carbonation curing, or concrete that combines any two or more of the above characteristics.

[0032] When the material of the temporary weight 15 is the above-mentioned CO2 absorbing concrete, for example, "CO2-SUICOM (registered trademark)" manufactured by Kajima Corporation can be used as the CO2 absorbing concrete. In this case, the process of making the temporary weight 15 absorb carbon dioxide is performed in advance, for example, in a factory where the precast block of the temporary weight 15 is manufactured.

[0033] By adopting CO2 absorbing concrete as the material of the temporary weight 15, the temporary weight 15 fixes carbon dioxide, and as a result, the amount of CO2 emissions in the construction of the waste disposal site 1 is reduced, and the environmental load is reduced. In addition, when concrete is carbonated, it becomes dense and the quality is improved, so the strength of the temporary weight 15 is improved, and the strength of the fixed work concrete 25 and the waterproof sheet fixing structure 30 is improved. In addition, the surface area of ​​the temporary weight 15 may be increased to increase the amount of carbon dioxide absorption. As a method for increasing the surface area of ​​the temporary weight 15, a through hole may be formed in the center of the temporary weight 15. Note that carbonation of concrete leads to neutralization of the concrete, and is therefore not preferable from the viewpoint of preventing corrosion of reinforcing bars in reinforced concrete. However, since the temporary weight 15 in this embodiment is an unreinforced precast concrete block, the problem of corrosion of reinforcing bars does not occur.

[0034] In order to further reduce the environmental load associated with the construction of the waste disposal site 1, the material of the concrete portion 17 may be the same environmental load reducing concrete as described above. In order to make the concrete portion 17 absorb carbon dioxide, forced carbonation curing treatment may be performed in the above-mentioned concrete pouring step as follows.

[0035] As shown in FIG. 6, after the fresh concrete 16 is poured into the groove 13, industrially derived granular dry ice 27 is placed on the top surface of the fresh concrete 16. Then, a cover 29 is placed on the groove 13 so as to cover the dry ice 27 from above. Both ends of the cover 29 may be fixed onto the waterproof sheet 7 via a predetermined fastener 31 installed on the top surface of the waterproof sheet 7 of the step portion 11. The fresh concrete 16 covered with the cover 29 in this manner is cured in a carbon dioxide atmosphere due to the presence of the dry ice 27 contained together in the cover 29, and the concrete portion 17 absorbs carbon dioxide (carbonation curing treatment). According to such forced carbonation curing treatment, equipment such as a gas cylinder and a gas injection device for supplying carbon dioxide is not required, and the amount of equipment to be prepared is reduced. The forced carbonation curing treatment as described above may be performed when concrete is poured in the groove 13. Instead of the dry ice 27, industrially derived carbon dioxide may be supplied from a gas cylinder into the cover 29.

[0036] In addition, in order to make the concrete portion 17 absorb carbon dioxide, the following process may be performed in the concrete pouring process. Dry ice is put into a concrete agitator 21 (FIG. 3) used in the concrete pouring process. Fresh concrete 16 before being poured into the groove portion 13 is mixed with the dry ice in the concrete agitator 21 and absorbs carbon dioxide. The fresh concrete 16 is then poured into the groove portion 13 and hardened to form the concrete portion 17 in which carbon dioxide has been absorbed. This process may deteriorate the fluidity of the fresh concrete 16, but since the inside of the groove portion 13 is unreinforced and highly flat, problems related to the fluidity of the fresh concrete 16 are unlikely to occur. Furthermore, since the concrete portion 17 is unreinforced concrete, there is no problem of corrosion of reinforcing bars due to carbonation (neutralization) of concrete.

[0037] As described above, by absorbing carbon dioxide into the concrete portion 17, the concrete portion 17 fixes the carbon dioxide, thereby reducing the amount of CO2 emissions in the construction of the waste disposal site 1 and reducing the environmental load. In addition, the carbonation improves the quality of the concrete portion 17, which in turn improves the strength of the fixing work concrete 25 and the waterproof sheet fixing structure 30.

[0038] Furthermore, according to the above-mentioned forced carbonation curing treatment, CO2 reacts with calcium hydroxide Ca(OH)2 in the concrete to form a dense calcium carbonate (CaCO3) layer on the surface of the concrete section 17. This prevents unreacted calcium components from the surface of the concrete section 17 from being included in the leachate when water from sprinkling, rain, etc. comes into contact with and accumulates on the surface of the concrete section 17 of the step section 11 during the service life of the waste disposal site 1. This has the advantage of reducing the risk of delay in stabilization of the waste disposal site 1 and scale formation in the leachate collection area (drainage system clogging caused by calcium components dissolved in the leachate combining with other impurities and precipitating).

[0039] In addition, the fixed concrete 25 in the waste disposal site 1 does not require high qualities such as compressive strength, long-term durability, and water-stopping ability compared to ordinary secondary concrete products, so problems are unlikely to occur even if a relatively large amount of carbon dioxide gas is fixed. Therefore, it is expected that the amount of CO2 emissions in the construction of the waste disposal site 1 will be significantly reduced.

[0040] The effects of the fixing method of the waterproof sheet 7 of this embodiment and the waterproof sheet fixing structure 30 constructed by this fixing method will be described below. In the fixing method of this embodiment, the temporary weight 15 is installed in the groove portion 13 in the temporary holding process for temporarily fixing the waterproof sheet 7, and then the temporary weight 15 is embedded in the concrete portion 17 in the concrete pouring process to become part of the fixing concrete 25. Therefore, there is no need to remove the temporary weight 15 once it has been installed, which results in improved workability. In addition, the work of removing the temporary weight 15 is no longer necessary, which shortens the construction period. In addition, the risk of damage to the waterproof sheet 7 due to the work of removing the temporary weight 15 is reduced.

[0041] Furthermore, in the concrete pouring process, the amount of concrete poured can be reduced by the volume of the temporary weight 15. In particular, when the temporary weight 15 is made of environmentally friendly concrete and the concrete portion 17 is made of normal concrete, the amount of normal concrete used is reduced, thereby reducing the environmental impact.

[0042] In addition, when CO2 absorbing concrete or concrete that has been subjected to forced carbonation curing is used as the material for the temporary weight 15, the surface of the temporary weight 15 becomes dense due to carbonation, so that adhesion to the concrete part 17 is good and the integrity of the fixing work concrete 25 is increased.

[0043] Furthermore, since each temporary weight 15 weighs 60 kg or less, it can be carried by a maximum of two workers P, and can be placed while being careful not to damage the waterproof sheet 7 during installation. Furthermore, if each temporary weight 15 weighs 30 kg or less, it is even more preferable since it can be carried and placed as described above by one worker P. Therefore, when installing the temporary weight 15 in the groove portion 13 in the temporary holding process, the work can be done by human power, and there is no need to introduce a lifting device or the like to the work site, which results in improved workability.

[0044] In the temporary holding process, the temporary weights 15 are arranged at predetermined intervals in the extension direction of the groove 13 (depth direction of the paper in FIG. 3), so that the fixed concrete 25 completed in the groove 13 also includes the temporary weights 15 at predetermined intervals. If steel such as H-shaped steel is used as the temporary weights 15, the finally completed fixed concrete 25 will have heavy parts containing steel and light parts not containing steel alternately in the extension direction of the groove 13. In this case, there is a possibility that a non-uniform force will act on the waterproof sheet 7 held down by the fixed concrete 25. In contrast, since the temporary weights 15 in this embodiment are made of concrete, the temporary weights 15 and the concrete parts 17 included in the fixed concrete 25 are made of approximately the same material, and the weights are uniform in the extension direction of the groove 13. Therefore, a uniform force acts on the waterproof sheet 7 in the extension direction of the groove portion 13, and as a result, the possibility of the waterproof sheet 7 being damaged at the contact portion between the waterproof sheet 7 and the fixing concrete 25 is reduced.

[0045] 4, the peripheral corners 15e of the lower surface 15a of the temporary weight 15 are rounded or haunched. This configuration reduces the possibility of the waterproof sheet 7 being damaged by the peripheral corners 15e coming into contact with the waterproof sheet 7 during the installation of the temporary weight 15 in the temporary holding step and during the period from the installation to the completion of the fixing work concrete 25.

[0046] The present invention can be implemented in various forms including the above-described embodiment and various modifications and improvements based on the knowledge of those skilled in the art. It is also possible to configure modified examples by utilizing the technical matters described in the above-described embodiment. The configurations of each embodiment may be used in appropriate combination.

[0047] The waterproof sheet fixing method and waterproof sheet fixing structure 30 according to the above embodiment may be applied not only to the step portion 11 but also to the flat area portion 35 (Fig. 1). That is, the waterproof sheet fixing method according to the above embodiment may be applied to the flat area portion 35 forming a horizontal plane, and a waterproof sheet fixing structure 30 as shown in Fig. 5 may be constructed. The flat area portion 35 is the ground surface of the ground 100 before the storage tank 3 is excavated into the ground 100, and is a horizontal plane located at the height of the top end of the storage tank 3 and extending continuously from the upper end of the inclined surface 5 toward the outside of the storage tank 3.

[0048] In the above embodiment, as shown in FIG. 5, the upper surface of the concrete portion 17 reaches the height of the step portion 11, but the upper surface of the concrete portion 17 may not reach the height of the horizontal surface of the step portion 11. In the above embodiment, as shown in FIG. 5, the height of the temporary weight 15 is lower than the depth of the groove portion 13, so that the entire temporary weight 15 is completely buried in the concrete portion 17, but this configuration is not limited to this. For example, the height of the temporary weight 15 may be increased so that the upper end of the temporary weight 15 protrudes upward from the concrete portion 17. However, in this case, there is a problem that a protrusion protruding above the step portion 11 exists, which may hinder the flow of leachate on the inclined surface 5. In addition, the flat area portion 35 may be used as a road on which vehicles pass during construction of the waste disposal site 1, etc. Therefore, if such a protrusion exists on the flat area portion 35, there is a problem that it is likely to obstruct vehicle traffic. In order to avoid the above problems, it is preferable that the height of the temporary weight 15 is lower than the depth of the groove portion 13 and the temporary weight 15 is completely buried in the concrete portion 17 as shown in FIG.

[0049] Furthermore, in the temporary holding step in the above embodiment, the temporary weight 15 is manually placed in the groove 13, but the temporary weight 15 may be placed using a lifting device or the like. Therefore, it is not essential that the weight of the temporary weight 15 be a weight that can be handled by a maximum of two workers. Even in this case, the temporary weight 15 once placed is buried as part of the fixing work concrete 25. Therefore, there is no need to remove the temporary weight 15 using a lifting device or the like thereafter, which improves workability.

[0050] Further, the temporary weight 15 may be structured so that a plurality of temporary weights are stacked in the groove portion 13. For example, in the embodiment illustrated in FIG. 7, two temporary weights 15J, 15K, a flat concrete block 15J and an upper concrete block 15K, are stacked vertically in the groove portion 13. The flat concrete block 15J has a rectangular flat plate shape in a plan view, and the upper concrete block 15K has a rectangular shape in a plan view that is slightly smaller than the flat concrete block 15J and is placed on the upper surface of the flat concrete block 15J. A thin groove or a recess (not shown) may be formed on the upper surface of the flat concrete block 15J, and the upper concrete block 15K may be placed using this thin groove or recess as a guide. The peripheral corner 15e of the lower surface 15a of the flat concrete block 15J has a haunch shape with, for example, C-chamfering. The peripheral corner 15e may have a rounded shape with, for example, R-chamfering.

[0051] In this case, the temporary holding step is performed, for example, as follows: Flat concrete blocks 15J are manually placed in groove 13 so as to be aligned in the extension direction of groove 13, as shown in Fig. 8(a) by worker P. Then, upper concrete block 15K is further manually placed on flat concrete block 15J, as shown in Fig. 8(b).

[0052] According to the structure in Fig. 7, the installation area of ​​the lower flat concrete block 15J is increased, thereby mitigating the local installation pressure from the temporary weights 15J, 15K on the waterproof sheet 7. Furthermore, the temporary weights 15J, 15K have a larger specific surface area per volume than the temporary weight 15, so that when CO2 absorbing concrete is used as the temporary weight material, the amount of CO2 absorption increases. Furthermore, the temporary weights 15J, 15K can reduce the weight per block compared to the temporary weight 15, so the burden on workers in the temporary holding process is reduced. [Explanation of symbols]

[0053] 1...waste disposal site, 5...inclined surface, 7...waterproof sheet, 11...step, 13...groove, 15...temporary weight, 15e...periphery corner, 16...fresh concrete, 17...concrete part, 27...dry ice, 29...cover, 35...flat area.

Claims

1. A waterproof sheet fixing method for fixing a waterproof sheet to a slope of a bowl-shaped waste disposal site, comprising: A groove is formed in a step portion in the middle of the inclined surface or in a flat portion extending from the upper end of the inclined surface to the outside so as to be recessed downward, A waterproof sheet laying step of laying a waterproof sheet on the inclined surface including the inside of the groove portion; A temporary holding process of placing a temporary weight on the waterproof sheet in the groove portion to hold down and temporarily fix the waterproof sheet by weight; A concrete pouring step of pouring concrete into the groove so as to bury the temporary weight.

2. The waterproof sheet fixing method according to claim 1, wherein the weight of each of the temporary weights is 60 kg or less.

3. The waterproof sheet fixing method according to claim 1 , wherein the peripheral corners of the lower surface of the temporary weight that contacts the waterproof sheet during the temporary holding step are rounded or haunched.

4. The waterproof sheet fixing method according to claim 1 , wherein in the concrete pouring step, the entire temporary weight is buried in the concrete.

5. The waterproof sheet fixing method according to claim 1 , wherein the material of the temporary weight is concrete.

6. The waterproof sheet fixing method according to claim 5, wherein the material of the temporary weight is environmentally friendly concrete.

7. The waterproof sheet fixing method according to claim 1 , wherein the concrete poured into the groove in the concrete pouring step is environmentally friendly concrete.

8. In the concrete pouring step, 8. The waterproof sheet fixing method according to claim 7, wherein the groove into which the concrete has been poured is covered with a cover, and dry ice is placed inside the cover, thereby subjecting the concrete to a carbonation curing treatment.

9. In the concrete pouring step, 8. The method for fixing a waterproof sheet according to claim 7, wherein fresh concrete before being poured into the groove is mixed with dry ice in a concrete agitator.

10. A waterproof sheet fixing structure for fixing a waterproof sheet to a slope of a bowl-shaped waste disposal site, A groove portion formed so as to be recessed downward in a step portion in the middle of the inclined surface or in a flat portion extending from the upper end of the inclined surface to the outside; A waterproof sheet laid on the inclined surface including the inside of the groove; A temporary weight installed on the waterproof sheet in the groove; A waterproof sheet fixing structure comprising: a concrete section poured into the groove section with the temporary weight embedded therein.

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