JP5020665B2 - Spraying method - Google Patents

Description

  The present invention relates to a spraying method for injecting a material containing bentonite to form a water stop layer made of the material.

  A spraying method is known as a method for forming a layer of concrete or mortar on a construction surface. The spraying method is generally classified into a wet spraying method and a dry spraying method. The wet spraying method is a method of forming a layer by spraying a spraying material prepared in advance by mixing a main material and water from a nozzle at the tip of a hose with the pressure of compressed air. On the other hand, the dry-type spraying method is a method of forming a layer by imparting adhesiveness to a material by mixing with water when jetting an air-kneaded powdery main material from a nozzle.

  The wet spraying method has features such as easy adjustment of the mixing ratio of the main material and water and good adhesion of the material. The wet spraying method has the advantage that the material can be sprayed with high uniformity due to these features, but on the other hand, since the material containing water is transferred by the hose, the material adheres to the inside of the hose or nozzle. There's a problem.

On the other hand, according to the dry-type spraying method, the material can be supplied stably without adhering to the inside of the hose or the like. However, in the dry spray method, water is added in the vicinity of the nozzle, so that the moisture in the material is not sufficiently uniformly dispersed, which may adversely affect the quality. In order to solve the problems related to the conventional spraying method as described above, various spraying devices and nozzles have been developed so far (see, for example, Patent Documents 1 and 2).
JP 2004-197553 A Japanese Patent Laid-Open No. 11-276939

  By the way, when building civil engineering structures such as radioactive waste disposal sites and highways and buildings such as foundations underground, water stoppage containing bentonite around the structure for the purpose of preventing entry of groundwater, etc. A layer is formed. The water-stopping layer provided in the radioactive waste treatment plant is required to have a particularly high water-stopping performance. Adoption of a wet spraying method is being studied for construction of a water-stopping layer that requires such a large scale and high water-stopping performance.

  In order to achieve high water-stopping performance, it is necessary to form a water-stopping layer formed by spraying a water-stopping material at a high density. One of the determinants of the spray density of a water-stopping material is the water content ratio of the material. When the water content ratio of the water-stopping material is within a predetermined range, the density of the water-stopping layer formed tends to improve as the value decreases. For this reason, it is desired that the water content of the water-stopping material be as low as possible. However, if a water-stopping material having an excessively low water content is used, the material may not adhere sufficiently to the spray surface. In this case, the non-adhering material is scattered as dust, resulting in loss of material or a worse working environment.

  On the other hand, if the moisture content is set high in order to improve the adhesion of the water-stopping material, not only will the spray density decrease, but the material will adhere to the inside of the hose or nozzle as the adhesion improves. May cause problems. Under such circumstances, there is room for improvement in forming a water stop layer that requires high water stop performance by the conventional wet spraying method.

  The present invention has been made in view of such circumstances, and even if a water-stopping material having a relatively high water content ratio is used in order to ensure adhesion to the spray surface, the water-stopping density is sufficiently high. An object is to provide a spraying method capable of forming a layer.

The present invention is a crumb product as waterproofing layer for building by blowing water stopping material containing the bentonite and water is more dense granulated, characterized and Turkey to inject crumb product A spraying method is provided. By jetting aggregates obtained from the water-stopping material, even when the water content of the water-stopping material is relatively high, a water-stopping layer can be formed in which the water-stopping material adheres at a high density. it can.

In the spraying method according to the present invention, the density of the water-stopping material can be increased by granulating the aggregate from the water-stopping material. That is, the spraying method of the present invention is to inject a water-stopping material containing a solid content mainly composed of bentonite to form a water-stopping layer made of the water-stopping material, A material preparation step for preparing a water-stopping material by mixing with water, a granulation step for granulating the aggregate so that the water-stopping layer constructed by spraying the water-stopping material has a higher density , After introducing the granule into the hose, a transfer step of transferring the aggregate in the hose with the pressure of the compressed gas and an injection step of injecting the aggregate from a nozzle provided at the tip of the hose are provided.

  In the spraying method of the present invention, the water-stopping material containing fine particles is granulated into aggregates through a granulation step. Since this aggregate is introduced into the hose and transferred, even if a water-stopping material with a relatively high water content is used, the water-stopping material is mixed with the hose in the hose as compared with the case where the water-stopping material is introduced into the hose. It can fully suppress that material adheres to the inside of a hose or a nozzle. Therefore, the water content ratio of the water-stopping material can be set high enough to ensure sufficient adhesion to the spray surface.

  As described above, according to the spraying method of the present invention, it is possible to sufficiently prevent the water-stopping material from adhering to the inside of the hose and the like, so that the continuous construction of the water-stopping layer can be efficiently performed. In addition, according to the spraying method of the present invention, the water-stopping material having the same moisture content is granulated in order to form a water-stopping layer by injecting the granulated aggregate after compacting the water-stopping material. Compared to the case where the mixture is sprayed as it is, a water-stopping layer is formed in which the water-stopping material is compacted at a high density. Thereby, a water stop layer with high water stop performance can be constructed.

  The aggregate in the spraying method of the present invention is a product in which a pair of gears is rotated to supply a water-stopping material to the meshing part of the pair of gears, and the water-stopping material is compacted in the meshing part. Preferably there is. By granulating the aggregate using a granulating apparatus having a pair of gears, the water-stopping material can be mechanically compacted, and the fine particles that cause adhesion can be more reliably reduced. Further, by allowing the water-stopping material to pass through the meshing portions of the pair of gears, it is possible to granulate aggregates in which the components constituting the water-stopping material are sufficiently uniformly dispersed.

  In the spraying method of the present invention, it is preferable to rotate the pair of gears at a constant speed. When the pair of gears are rotated at a constant speed, a certain amount of aggregated particles can be continuously granulated. By introducing this into the hose, a certain amount of aggregate can be continuously ejected from the nozzle at the tip of the hose.

  It is preferable that the pair of gears included in the granulating apparatus are detachable. If the pair of gears are detachable, the physical properties (for example, the particle size and the degree of compaction) of the aggregated material can be appropriately set by attaching another pair of gears to the granulator instead. The properties of the aggregate may be set according to the composition of the water stop material, the water stop performance required for the water stop layer, and the like.

  In this invention, it is preferable that the content rate of the bentonite contained in solid content is 95 mass% or more on the mass basis of solid content. In general, when a water-stopping material is prepared using a solid content of bentonite content of 95% by mass or more and sprayed with aggregates to form a water-stopping layer, particularly high water-stopping performance is achieved. can do. For this reason, it is suitable for formation of a water stop layer which requires particularly high water stop performance such as a radioactive waste treatment plant. However, even if solid content with low bentonite content (bentonite content: 5% by mass or more and less than 95% by mass) is used, a certain water-stopping performance can be obtained. Accordingly, the bentonite content may be set.

When using a solid content of bentonite content of 95% by mass or more, in the material preparation step, the solid content and water are mixed so that the water content of the water-stopping material is in the range of 15 to 30%. It is preferable to do. Here, the water content ratio w (%) of the water-stopping material is defined by the following formula (1). In the formula, W _w is the mass of water contained in the water stop material, W _s is the solids mass such as bentonite and sand contained in the water cutoff material respectively.
w = (W _w / W _s ) × 100 (1)

  According to the present invention, there is provided a spraying method capable of forming a waterstop layer having a sufficiently high density even when a waterstop material having a relatively high water content ratio is used in order to ensure adhesion to the spray surface. be able to.

  Hereinafter, an example of a preferred embodiment of a spraying method according to the present invention will be described in detail with reference to the drawings. Here, the case where the water stop layer of the radioactive waste disposal site constructed in the ground is formed will be described as an example. For convenience of the drawings, the dimensional ratios in the drawings do not necessarily match those described.

  FIG. 1 is an example of a front sectional view of a radioactive waste disposal site. The radioactive waste disposal site 10 shown in the figure is for geological disposal of radioactive waste. The radioactive waste disposal site 10 has a mine 1, and the radioactive waste 2 is buried in the mine 1 and discarded. The mine shaft 1 is made of concrete, for example. In the mine shaft 1, a waste body accommodating portion 3 for accommodating the radioactive waste 2 is provided. The radioactive waste 2 is placed in the waste storage unit 3 in a state of being stored in a metal container.

  Around the waste container 3, water-stopping layers 5 a to 5 d made of a water-stopping material containing bentonite are provided. Filling portions 7a to 7d made of, for example, concrete are provided on the outer side of the water blocking layers 5a to 5d. The water stop layer provided around the waste container 3 prevents the groundwater from flowing to the waste container 3.

  The spray construction system and water stop material used for formation of a water stop layer are demonstrated. FIG. 2 is a diagram showing a construction system used in the present embodiment, and is a schematic diagram showing a state in which the worker 50 holds the nozzle 9. The construction system 100 shown in the figure includes a compressor 20 that manufactures compressed air for injecting a water-stopping material, a granulator 30 that prepares the water-stopping material and granulates aggregates from the material, Compressed air from the compressor 20 and aggregated material from the granulating device 30 are supplied, respectively, and an injection device 40 for injecting the aggregated material with compressed air is provided.

  The compressor 20 is for producing compressed air to be supplied to the injection device 40. As the compressor 20, a conventionally known apparatus such as a reciprocating type or a rotary type can be used as long as the pressure can be increased to a sufficient pressure and the aggregate can be injected.

  The granulator 30 includes a hopper 31 that mixes dried bentonite and water to prepare a water-stopping material, and a pair of gears provided at the lower portion of the hopper 31. Bentonite to which water is added so as to have a predetermined moisture content is supplied into the hopper 31 by the crane 35, and the water-stopping material is prepared by mixing bentonite and water (material preparation step).

  FIG. 3 is a schematic cross-sectional view showing the structure of the granulating apparatus 30. As shown in the figure, a water-stopping material is introduced into the meshing portion 33 of the pair of gears 32a and 32b and mechanically compacted to granulate aggregates (particle size: about 20 mm) (granulation). Process). The pair of gears 32a and 32b are configured to rotate at a constant speed by a driving device (not shown) and to continuously granulate a certain amount of aggregate.

  The pair of gears 32a and 32b included in the granulating apparatus 30 is detachable, and another pair of gears can be mounted instead of the gears 32a and 32b. By appropriately selecting and mounting a pair of gears having different gear pitches and tooth depths, the particle size and the degree of compaction of the aggregate can be changed. What is necessary is just to change suitably the particle size of a aggregate according to the internal diameter of the nozzle to be used, for example. The degree of compaction of the aggregate is preferably such that the shape is maintained in the hose while the shape is broken by an impact sprayed from the nozzle 9 and sprayed onto the target surface. What is necessary is just to change suitably the compaction degree of a aggregate according to the transfer distance by a hose, and the shape of a nozzle, for example.

  The bentonite used for the preparation of the water-stopping material includes those produced from bentonite raw ore. The content of bentonite in the solid content contained in the water-stopping material is preferably 95% by mass or more (based on the mass of the solid content), and more preferably 98% by mass or more. Furthermore, it is most preferable that the solid content consists essentially of bentonite. When the content of bentonite is less than 95% by mass, the water-stopping performance of the water-stopping layer formed tends to be lower than that of 95% by mass or more. However, even if solid content with low bentonite content (bentonite content: 5% by mass or more and less than 95% by mass) is used, a certain water-stopping performance can be obtained. Accordingly, the bentonite content may be set. In addition, sand, earth, etc. are mentioned as components other than bentonite contained in solid content.

  In the case of using a solid content of bentonite content of 95% by mass or more, the water content ratio of the water-stopping material is preferably in the range of 15 to 30% from the viewpoint of obtaining a sufficiently compacted aggregate. When the water content is less than 15%, it becomes difficult to granulate aggregates from the water-stopping material, and the adhesion of the water-stopping material becomes insufficient, and the material is likely to scatter during the spraying operation. On the other hand, if the water content ratio exceeds 30%, the water-stopping material easily adheres to the hose 8 and it becomes difficult to form a sufficiently high-density water-stopping layer. The lower limit of the water content ratio of the water stop material is preferably 16%, and more preferably 17%. Further, the upper limit of the water content ratio of the water stop material is preferably 29%, more preferably 28%, and further preferably 27%.

  The injection device 40 is an apparatus for introducing the aggregated material into the hose 8 and injecting the introduced aggregated material. FIG. 4 is a schematic diagram showing the structure of the injection device 40. As shown in the figure, the injection device 40 includes three disk members that are stacked, an upper stage, a middle stage, and a lower stage. The three disk members 41, 42 and 43 are connected to each other so that only the disk member 42 located in the middle stage rotates. The upper disk member 41 and the middle disk member 42 include two through holes 41a and 41b and two through holes 42a and 42b. Aggregates from the granulator 30 are supplied to the through holes 41 a of the upper disk member 41. On the other hand, the air from the compressor 20 is supplied to the through hole 41 b of the upper disk member 41. The lower disk member 43 is provided with one through hole 43b, to which the base end of the hose 8 is connected. The through hole 43 b is provided at a position facing the through hole 41 b of the disk member 41.

  The operation of the injection device 40 is as follows. The aggregates supplied from the granulator 30 are accommodated in one through hole 42a of the middle disk member 42 through the through hole 41a of the upper disk member 41. As the middle disk member 42 rotates, the aggregates accommodated in the through holes 42a move toward the positions of the through holes 41b and the through holes 43b. When the aggregate in the through hole 42a moves to the positions of the through hole 41b and the through hole 43b, the aggregate is injected to the through hole 43b side by the compressed air from the through hole 41b and passes through the through hole 43b. Introduced in. At this time, the aggregated material from the granulating apparatus 30 is again accommodated in the other through hole 42b of the middle disk member 42.

  The aggregates and compressed air are respectively supplied to the through holes 41a and 41b of the upper disk member 41, and the middle disk member 42 is rotated at a constant speed so that the aggregates are continuously fed into the hose 8. Introduce. And the aggregate introduced into the hose 8 is transferred in the direction of the tip of the hose by the pressure of the compressed air (transfer process), and the aggregate is continuously injected from the nozzle 9 together with the compressed air (injection process). . As the nozzle 9 provided at the tip of the hose 8, various conventionally known nozzles can be used. However, it is preferable to use a nozzle having an inner diameter larger than the particle size of the aggregate from the viewpoint of suppressing adhesion of the water-stopping material inside the nozzle and avoiding blockage.

  Next, a method for forming the water blocking layer 5 of the radioactive waste disposal site 10 by the spraying method according to the present embodiment will be described.

  When constructing the radioactive waste disposal site 10 shown in FIG. 1, prior to placing the waste container 3 in the tunnel 1, the filling portions 7 a, 7 b, 7 c are formed on the left and right walls and bottom of the tunnel 1. Form. The left and right filling portions 7a and 7b have a distance of about 1 m between the left and right wall surfaces of the waste body housing portion 3 and the wall surfaces of the filling portions 7a and 7b when the waste body housing portion 3 is placed in the tunnel 1. Provide to be. Further, the water blocking layer 5a is laid on the filling portion 7c with a thickness of about 1 m. The laying of the water blocking layer 5a may be performed by the spraying method according to the present embodiment, or may be performed by construction of a vibration roller or the like.

  The waste body accommodating portion 3 is placed in the tunnel 1 having the above-described configuration. If the waste body accommodating part 3 is mounted, as shown in FIG. 5, the water stop material (agglomerate) is sprayed between the filling part 7a and the waste body accommodating part 3, and the water stop layer 5b is formed. The nozzle 9 is held downward, and the water-stopping material is gradually filled from the lower part of the mine shaft 1 toward the upper part. If the water blocking layer 5b is formed between the filling part 7a and the waste body container 3, the water blocking layer 5c is formed between the filling part 7b and the waste body container 3 in the same manner.

  When the water-stopping material is sprayed and the water-stopping layers 5b and 5c are formed on the side surfaces of the waste container 3, the water-stopping layer is formed on the upper surface of the waste container 3 by the spraying method according to this embodiment. 5d is formed. Thereafter, as shown in FIG. 1, a filling portion 7 d is formed in a space between the water blocking layer 5 d and the upper wall surface of the tunnel 1. In this way, the water stop layer 5 made of a water stop material is formed around the waste body accommodating portion 3 to prevent the groundwater from flowing to the waste body containing portion 3.

  By implementing the spraying method according to the present embodiment, the following effects are exhibited. That is, in order to achieve a high water-stopping performance, it is necessary to form a water-stopping layer in which the water-stopping material is compacted with high density. In the spraying method of this embodiment, the water-stopping material is mechanically consolidated. Since the granulated aggregate is sprayed, it is possible to form a high-density water-stopping layer as compared with the conventional spraying method. Therefore, even in a place where a device such as a rolling roller cannot be used, it is possible to form a water-stopping layer having a water-stopping performance as high as that required for a radioactive waste disposal site. Moreover, since a water-stopping layer having high water-stopping performance can be formed by a simple method called a spraying method, it is suitable for forming a water-stopping layer in a narrow portion.

  Further, according to the spraying method according to the present embodiment, the aggregated material is granulated from the water-stopping material, and this is introduced into the hose and sprayed. Therefore, the water-stopping material having a relatively high water content ratio is used. However, it is possible to sufficiently suppress the material from adhering to the inside of the hose 8 or the nozzle 9. Therefore, when forming a large scale water-stopping layer, the spraying operation can be efficiently performed when the spraying operation is continuously performed for a long time. In addition, since the fine particles that cause dust are sufficiently reduced by using the water-stopping material as aggregates, it is possible to suppress the scattering of dust during spraying operations, improve the work environment, The loss rate of the material can also be reduced.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the granulation step of the above embodiment, the water-stopping material passes only once through the meshing portion of the pair of gears, but the material may pass through the meshing portion a plurality of times. For example, the spraying method of the present invention may include a returning step of returning at least a part of the granulated aggregate to the granulating device 30. By returning the aggregated material into the hopper 31 and allowing it to pass through the meshing portion 33 again, the uniformity of the composition of the water-stopping material is further increased, and a water-blocking layer having a higher density can be formed. Instead of the returning step, the water-stopping material is supplied to a granulation system in which a plurality of granulation apparatuses each having a pair of gears are installed in series, and the water-stopping material sequentially passes through the plurality of meshing portions. You may make it do. Furthermore, the method of densifying the water-stopping material is not limited to a pair of gears. For example, the water-stopping material that has been compacted by rolling, tamping, or the like is cut into dice or granule to obtain aggregates. May be.

  Moreover, in the said embodiment, although the water stop material is sprayed on all between the filling parts 7a-7d and the waste body accommodating part 3, it can do in the part which can ensure the work space in the mine shaft 1. It is possible to use a compacting machine as small as possible, or to spread a bentonite block, and to carry out the spraying method of the present invention only in the remaining narrow portion to form a water stop layer. In addition, the filling portions 7a to 7d may not be formed in the mine shaft 1 and all of the space between the inner wall surface of the mine shaft 1 and the waste body housing portion 3 may be filled with a water stop material. Moreover, you may use the mixture of a bentonite and cement, for example as a water stop material. Furthermore, when high water-stopping performance is not required, a water-stopping material prepared by mixing bentonite with earth and sand or fibers may be used. The nozzle 9 may be directly held by an operator, or may be mounted on a machine such as a robot and operated or remotely operated.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these.

<Blowing test 1>
Example 1
Using the construction system having the same configuration as the construction system 100 shown in FIG. First, bentonite whose moisture content was adjusted in advance so that the water content was 20% was introduced into the hopper of the granulator.

  After starting the compressor and the injection device, the operator held the nozzle toward the construction surface and prepared for the spraying operation. After completion of preparation, the gears of the granulator were rotated to granulate aggregates from the waterstop material. The aggregated material was continuously supplied to the injection device and sprayed with compressed air.

  In this example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. Further, it was confirmed that the water-stopping material sprayed from the nozzle adhered well on the construction surface, and the water-stopping material having a water content ratio of this example had good adhesion. A part of the water stop layer formed on the construction surface was collected, and the dry mass (dry density) of the water stop material per unit volume of the water stop layer was measured.

(Example 2)
A spray test and a dry density measurement of the water-stopping layer were carried out in the same manner as in Example 1 except that a water-stopping material having a water content of 21% was prepared. In this example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. Further, it was confirmed that the water-stopping material sprayed from the nozzle adhered well on the construction surface, and the water-stopping material having a water content ratio of this example had good adhesion.

(Example 3)
A spray test and measurement of the dry density of the water-stopping layer were carried out in the same manner as in Example 1 except that a water-stopping material having a water content ratio of 22% was prepared. In this example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. Further, it was confirmed that the water-stopping material sprayed from the nozzle adhered well on the construction surface, and the water-stopping material having a water content ratio of this example had good adhesion.

Example 4
A spray test and a dry density measurement of the water-stopping layer were carried out in the same manner as in Example 1 except that a water-stopping material having a water content ratio of 24.5% was prepared. In this example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. Further, it was confirmed that the water-stopping material sprayed from the nozzle adhered well on the construction surface, and the water-stopping material having a water content ratio of this example had good adhesion.

(Comparative Example 1)
A spray test and a water stop layer were carried out in the same manner as in Example 1 except that a water stop material having a water content of 18% was prepared, and the spray device was supplied as an admixture without making this agglomerated. The dry density measurement of was carried out. In this comparative example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. However, a part of the water-stopping material sprayed from the nozzle did not adhere to the construction surface, and the water-stopping material that did not adhere scattered as dust.

(Comparative Example 2)
A spray test and a water stop layer were carried out in the same manner as in Example 1 except that a water stop material having a water content of 20% was prepared, and that the spray device was supplied as an admixture without making this agglomerated. The dry density measurement of was carried out. In this comparative example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. However, a part of the water-stopping material sprayed from the nozzle did not adhere to the construction surface, and the water-stopping material that did not adhere scattered as dust. Moreover, in this comparative example, compared with Example 1 which uses the water stop material of the same moisture content, the dry density of the water stop layer became 0.07 Mg / cm < ³ > small.

(Comparative Example 3)
A spray test and stop were carried out in the same manner as in Example 1 except that a water-stopping material having a water content of 21% was prepared and the spray device was supplied in the form of an admixture without making this agglomerated. The dry density of the aqueous layer was measured. In this comparative example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. Further, it was confirmed that the water-stopping material injected from the nozzle adhered well on the construction surface, and the water-stopping material having a water content ratio of this comparative example had good adhesion. However, in this comparative example, the dry density of the water blocking layer was reduced by 0.07 Mg / cm ^{3 as} compared to Example 2 using the water blocking material having the same water content.

The results of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Tables 1 and 2 and FIG.

<Blowing test 2>
(Example 5)
The spray test and the dry density measurement of the water-stopping layer were carried out in the same manner as in Example 1 except that the water-stopping material was prepared so that the water content was 21%. In this example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. Further, it was confirmed that the water-stopping material sprayed from the nozzle adhered well on the construction surface, and the water-stopping material having a water content ratio of this example had good adhesion.

(Example 6)
Example 5 except that the aggregates discharged from the granulator were again introduced into the hopper of the granulator and the aggregates obtained by passing the granulator twice were supplied to the injection device. Similarly, a spray test and a dry density measurement of the water-stopping layer were performed. In this example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. Moreover, it confirmed that the water stop material injected from the nozzle adhered favorably on the construction surface, and the water stop material according to the present example has good adhesion.

(Example 7)
The spray test and the dry density measurement of the water-stopping layer were carried out in the same manner as in Example 6 except that the aggregated product obtained by passing the granulation device three times was supplied to the spraying device. In this example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. Moreover, it confirmed that the water stop material injected from the nozzle adhered favorably on the construction surface, and the water stop material according to the present example has good adhesion.

(Comparative Example 4)
The spray test and the dry density measurement of the water-stopping layer were carried out in the same manner as in Example 5, except that the water-stopping material was supplied as an admixture without making the water-stopping material agglomerated. In this comparative example, the spraying operation could be carried out without the occurrence of blockage in the hose or nozzle. However, in this comparative example, the dry density of the water-stopping layer was reduced as compared with Examples 5 to 7 in which water-stopping materials having the same water content ratio were used as aggregates.

  The results of Examples 5 to 7 and Comparative Example 4 are shown in FIG.

  From the above results, when the water-stopping material is granulated into aggregates and then sprayed to form a water-stopping layer, the water-stopping material is compacted more densely than in the case of spraying the mixture as it is. It was shown that an aqueous layer can be formed. It was also found that a higher density water stop layer can be formed when the water stop material passes through the meshing portion of the gear a plurality of times.

It is a front sectional view of a radioactive waste disposal site. It is a schematic diagram which shows the state in which the operator is holding the nozzle in the construction system suitable for the spraying method of this invention. It is a schematic cross section which shows the structure of a granulation apparatus. It is a schematic cross section which shows the structure of an injection device. It is front sectional drawing of the creation process of a radioactive waste disposal site. It is a graph which shows the relationship between a moisture content and the dry density after spraying. It is a graph which shows the relationship between the frequency | count of passage of the meshing part of a water stop material, and the dry density after spraying.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Tunnel, 2 ... Radioactive waste, 3 ... Waste body accommodating part, 5a, 5b, 5c, 5d ... Water stop layer, 7a, 7b, 7c, 7d ... Filling part, 8 ... Nozzle, 9 ... Hose, 10 ... Radioactive waste disposal site, 20 ... compressor, 30 ... granulating device, 32a, 32b ... gear (pair of gears), 33 ... meshing part, 40 ... injection device, 100 ... construction system.

Claims (6)

Blowing the water stop layer be constructed sprayed water stopping material containing the bentonite and water granulated crumb was such that the higher density, and wherein the benzalkonium be injected the crumb product Attaching method. In the spraying method of injecting a water-stopping material containing a solid content mainly composed of bentonite to form a water-stopping layer made of the water-stopping material,
A material preparation step of preparing the water-stopping material by mixing the solid content with water;
A granulation step of granulating aggregates so that the waterstop layer constructed by spraying the waterstop material has a higher density ;
After introducing the aggregate into the hose, a transfer step of transferring the aggregate in the hose with the pressure of compressed gas;
An injection step of injecting the aggregate from a nozzle provided at the tip of the hose;
A spraying method characterized by comprising:   The aggregated material is formed by rotating the pair of gears and supplying the water-stopping material to the meshing part of the pair of gears so that the water-stopping material is compacted in the meshing part. The spraying method according to claim 2, wherein:   The spraying method according to claim 3, wherein the pair of gears are rotated at a constant speed.   The spraying method according to claim 3 or 4, wherein the pair of gears are detachable.   The content of the bentonite contained in the solid content is 95% by mass or more based on the mass of the solid content, and the water content ratio of the water-stopping material is in the range of 15 to 30% in the material preparation step. The spraying method according to any one of claims 2 to 5, wherein the solid content is mixed with water.

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