Backfilling material manufacturing method, cavity backfilling method, backfilling material manufacturing device, and backfilling device

Abstract

To produce a backfilling material comprising uniformly mixed large-diameter and small-diameter granules in a dry state and utilize the produced backfilling material to backfill a cavity homogeneously and efficiently.SOLUTION: Large-diameter granules and small-diameter granules are individually conveyed with a screw feeder, and at a site to which they have been conveyed, clearances among the large-diameter granules unloaded from the screw feeder are filled with the small-diameter granules, thus producing a backfilling material.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a backfilling material containing large-diameter granules and small-diameter granules, a method for backfilling a cavity by filling it with a backfilling material manufactured by the backfilling material manufacturing method, a backfilling material manufacturing apparatus, and a backfilling apparatus. [Background technology]

[0002] For example, a high-level radioactive waste disposal site planned deep underground will ensure the prevention of leachate leakage and the mechanical safety of the site by backfilling all spaces, such as access tunnels, connecting tunnels, and main tunnels, excavated from above ground for the purpose of construction and operation, to their original state upon closure of the site. Bentonite mixed soil is being considered as a material to be used for backfilling these tunnels.

[0003] Bentonite-mixed soil is widely used in sites where high water impermeability is required, such as containment works for general waste and contaminated soil, foundation ground works for structures, etc. For example, in Patent Document 1, bentonite-mixed soil is used as a material for the impermeable layer formed at the bottom and on the slopes of a facility where waste is disposed.

[0004] Specifically, on the slopes of the facility, bentonite and water are mixed and stirred with excavated soil and other base material to produce bentonite mixed soil, which is then sprayed as a spraying material to form an impermeable layer, while on the bottom of the facility, the base material, bentonite and water are mixed and stirred, granulated, and the granulated material is spread out and then compacted to form an impermeable layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-87579 A Summary of the Invention [Problem to be solved by the invention]

[0006] The spraying of bentonite-mixed soil and the spreading and compaction of granulated material mainly made of bentonite as disclosed in Patent Document 1 are suitable for covering the slopes and bottoms of facilities with an impermeable layer. However, neither of these construction methods is suitable for filling a long, large-capacity backfill space such as the tunnel described above with bentonite-mixed soil.

[0007] In this situation, a method that can be considered is to use a screw feeder (screw conveyor) used as an earth removal device for earth pressure shields to transport the bentonite mixed soil to the tunnel and backfill it. By using a screw feeder, not only can large amounts of bentonite mixed soil be transported continuously, but the bentonite mixed soil can also be handled without adding water.

[0008] However, because the particle size of the bentonite and the base material in bentonite mixed soil is significantly different, the base material and the bentonite are easily separated and the quality is easily deteriorated by various events such as transportation in a dry state, mechanical vibration during transportation by a screw feeder, and when the soil falls after being discharged from the screw feeder. If such deteriorated bentonite mixed soil is filled into the backfill space, it may not be able to fully demonstrate the permeability performance expected at the time of design.

[0009] The present invention has been developed in consideration of such problems, and its main objective is to produce a backfilling material that is a uniform mixture of large-diameter granular material and small-diameter granular material in a dry state, and to use the produced backfilling material to backfill cavities uniformly and efficiently. [Means for solving the problem]

[0010] In order to achieve this objective, the method for manufacturing backfill material of the present invention is characterized in that large-diameter granular materials and small-diameter granular materials are transported separately by a screw feeder, and at the destination, the small-diameter granular materials are dropped from the screw feeder to fill the gaps between the large-diameter granular materials to produce backfill material.

[0011] The method for producing backfill material of the present invention is characterized in that the backfill material is a bentonite mixed soil, the large-diameter granules contain gravel, and the small-diameter granules contain bentonite.

[0012] According to the method for producing backfill material of the present invention, large and small granular materials are transported separately by a screw feeder and dropped at the destination, so that the small granular materials fill the gaps between the large granular materials. Therefore, it is possible to continuously produce high-quality backfill material in which large and small granular materials in a dry state are mixed uniformly without being affected by mechanical vibrations caused by the screw feeder. In addition, when using bentonite mixed soil as backfill material, it can be produced in a dry state, so that complicated work such as water adjustment can be omitted, and it is easier to handle during construction than bentonite mixed soil that has been water-adjusted.

[0013] The method for backfilling a cavity of the present invention is a method for backfilling a cavity in the ground, which involves filling the cavity in the ground with the backfilling material produced by the backfilling material manufacturing method of the present invention, and is characterized in that the large-diameter granular material and the small-diameter granular material are transported toward the cavity, and the cavity is filled while the backfilling material is produced in the cavity.

[0014] The method for backfilling a cavity of the present invention is characterized in that the backfilling material is continuously produced while the discharge port of the screw feeder is submerged in the previously produced backfilling material.

[0015] According to the method for backfilling a cavity of the present invention, the manufacturing process of the backfilling material can be omitted, and the cavity can be backfilled while the backfilling material is being manufactured in the cavity, so that the efficiency of the backfilling work can be significantly improved. Also, by burying the discharge port of the screw feeder in the backfilling material to be filled in the cavity first, these can be pressed by the backfilling material to be manufactured later. As a result, the backfilling material to be filled in the cavity is compacted, so that the work of rolling and compacting, which is generally carried out separately, can be omitted.

[0016] The method for backfilling a cavity of the present invention is characterized in that the density of the backfilling material for the cavity is evaluated, and when a preset density is reached, production of the backfilling material is stopped.

[0017] The method for backfilling a cavity of the present invention is also characterized in that the cavity is a tunnel in a waste disposal site.

[0018] According to the method for backfilling a cavity of the present invention, the backfilling material in the cavity can be compacted to a preset density, and the screw feeder can be prevented from being overloaded and breaking down. In addition, when the cavity is a tunnel, by repeating the process of stopping the production of backfilling material, retreating the screw feeder, and restarting the production of backfilling material, it is possible to continuously provide backfilling material compacted to a uniform density in the longitudinal direction of the tunnel.

[0019] This makes it possible to uniformly backfill the tunnel with backfill material over its entire length, even when the planned backfilling range of the tunnel is long. On the other hand, if it is necessary to produce backfill material with a different mix due to changes in the properties of the surrounding rock mass in the planned backfilling range of the tunnel, it is possible to easily produce backfill material with a different mix without interrupting the backfilling work by appropriately adjusting the supply amount of large-diameter granular material and small-diameter granular material to the screw feeder. In this way, it is also possible to continuously backfill the tunnel while appropriately adjusting the mix of the backfill material in response to changes in the surrounding rock mass.

[0020] The backfill material manufacturing apparatus of the present invention is a backfill material manufacturing apparatus used in the backfill material manufacturing method of the present invention, and is characterized in that it is equipped with the screw feeder and hopper, and storage sections for storing each of the large-diameter granular materials and the small-diameter granular materials are arranged in pairs on either side of a partition member provided inside the hopper, and opening and closing gates that are alternately opened and closed are installed at the bottom of the pair of storage sections.

[0021] The backfill material manufacturing apparatus of the present invention is a backfill material manufacturing apparatus used in the backfill material manufacturing method of the present invention, and is characterized in that it is equipped with the screw feeder and a hopper, and two of the screw feeders are arranged in parallel with a gap in the vertical direction and each discharge outlet is arranged with a position offset in the axial direction, a small diameter storage section for storing the small diameter granular material is provided in the hopper provided with the screw feeder located above, and a large diameter storage section for storing the large diameter granular material is provided in the hopper provided with the screw feeder located below.

[0022] According to the backfilling material manufacturing device of the present invention, since the backfilling material can be manufactured at the destination by simply storing the large-diameter granular material and the small-diameter granular material in the hopper, there is no need to install a separate facility such as a plant for manufacturing the backfilling material on-site. Also, by appropriately changing the supply amount of the large-diameter granular material and the small-diameter granular material to the screw feeder, it is possible to easily manufacture backfilling materials with different compositions.

[0023] The backfilling device of the present invention is a cavity backfilling device that fills cavities in the ground with backfilling material, and is characterized in that it is equipped with the backfilling material manufacturing device of the present invention and an evaluation means for evaluating the density of the backfilling material filled in the cavity.

[0024] The backfilling device of the present invention can handle a series of operations related to backfilling, including the production of backfilling material, the transportation and filling of the backfilling material into the cavity, the compaction of the backfilling material filled into the cavity, and the management of the finished shape. This makes it possible to improve the efficiency of backfilling, thereby contributing to reducing construction costs and shortening the construction period. Furthermore, by further installing equipment for supplying large-diameter granular material and small-diameter granular material, it is possible to automate the backfilling. Effect of the Invention

[0025] According to the present invention, it is possible to produce backfilling material that is a uniform mixture of large-diameter granular material and small-diameter granular material in a dry state, and to use the produced backfilling material to backfill cavities uniformly and efficiently. [Brief description of the drawings]

[0026] [Figure 1] 1 is a diagram showing an outline of a high-level radioactive waste disposal site in an embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing a backfilling material manufacturing apparatus according to an embodiment of the present invention (part 1). [Diagram 3] FIG. 2 is a diagram showing a backfilling material manufacturing apparatus according to an embodiment of the present invention (part 2). [Figure 4] FIG. 2 is a diagram showing a backfilling device according to an embodiment of the present invention. [Diagram 5] FIG. 1 is a diagram showing a procedure for backfilling an access tunnel in an embodiment of the present invention (part 1). [Figure 6] FIG. 2 is a diagram showing a procedure for backfilling an access tunnel in an embodiment of the present invention (part 2). [Figure 7] FIG. 1 is a diagram showing a scattering-type RI density meter according to an embodiment of the present invention. [Figure 8] FIG. 13 is a diagram showing how to evaluate the density of a backfill material in an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The present invention utilizes a screw conveyor to separately transport large-diameter and small-diameter dry granular materials and then drops them into the cavity to which they are transported, thereby continuously producing a high-quality backfill material in which the materials are uniformly mixed, and backfilling the cavity homogeneously and efficiently.

[0028] Below, using the example of backfilling an access tunnel to a high-level radioactive waste disposal site with backfilling material, a method for manufacturing backfilling material, a method for backfilling a cavity, a backfilling material manufacturing apparatus, and a backfilling apparatus will be described with reference to Figures 1 to 8.

[0029] In this embodiment, the threshold for large and small granular matter is 2 mm, and granular matter exceeding the threshold is classified as large granular matter, while granular matter below the threshold is classified as small granular matter, but the threshold is not limited to 2 mm and can be changed as appropriate. In addition, when the large and small granular matter include soil material, the dry state includes not only the bone dry state but also the air-dry state and the surface dry state.

[0030] <<<<High-level radioactive waste disposal site>>>> As shown in Figure 1(a), a disposal site 10 for high-level radioactive waste planned deep underground comprises a disposal tunnel 11, a connecting tunnel 12 that connects to the disposal tunnel 11, and an access tunnel 13 that extends from the connecting tunnel 12 to the ground. During operation, waste is transported to the disposal tunnel 11 using the access tunnel 13 and the connecting tunnel 12, and the waste is appropriately treated and disposed of in the disposal tunnel 11.

[0031] Furthermore, when closing the disposal site 10, the disposal tunnels 11 and the connecting tunnels 12 are filled with a filling material and closed with plugs or the like to prevent the filling material from moving or flowing out. The access tunnels 13 are uniformly closed with backfill material M to return them to their original state before excavation. The backfill material M is required to have low permeability equivalent to that of the surrounding rock mass, and to have self-sealing properties that allow it to uniformly close the access tunnels 13 and blend in with the surrounding rock mass without creating gaps. For this reason, bentonite mixed soil is used as the backfill material M.

[0032] The bentonite-mixed soil is produced on-site, using on-site generated soil as the base material, and mixing this base material with bentonite in a ratio designed based on the results of laboratory tests, etc., to ensure the desired water-proofing performance. The high-level radioactive waste disposal site 10 will be built in stable bedrock deep underground, so there are plans to select excavated waste from this bedrock as the base material. The backfill material M for the access tunnel 13 is produced by mixing gravel M1 obtained by crushing the excavated waste and adjusting its grain size, for example, with fine-grained fraction M2 containing bentonite, as shown in Figure 1(b).

[0033] The gravel fraction M1 is adjusted to a particle size of about 2 to 75 mm and classified as large-diameter granules. The fine-grained fraction M2 contains bentonite and is adjusted to a particle size of 2 mm or less and classified as small-diameter granules. The fine-grained fraction M2 may be bentonite only, or may contain other soil materials such as sand as long as the particle size is about 2 mm or less. The bentonite-mixed soil may contain not only the gravel fraction M1 and the fine-grained fraction M2, but also granulated bentonite with a particle size exceeding 2 mm. In this case, the gravel fraction M1 and the granulated bentonite are classified as large-diameter granules, and the fine-grained fraction M2 is classified as small-diameter granules.

[0034] In producing the above bentonite mixed soil, a backfilling material manufacturing device MD is used, which can transport the gravel portion M1 classified as large-diameter granules and the fine-grained portion M2 classified as small-diameter granules individually to a predetermined position in the access tunnel 13, as shown in Figure 2, and drop the gravel portion M1 at the destination to fill the gaps in the gravel portion M1 with the fine-grained portion M2.

[0035] In this way, it becomes possible to continuously produce high-quality bentonite in which the gravel fraction M1 and the fine grain fraction M2 are uniformly mixed in the access tunnel 13 without being affected by mechanical vibrations caused by the screw feeder. In addition, because the bentonite mixed soil can be produced in a dry state, troublesome work such as adjusting the amount of water added can be omitted, and the bentonite mixed soil is easier to handle during construction compared to when adjusting the amount of water added.

[0036] The backfill material manufacturing device MD for manufacturing the backfill material M will be described in detail below, taking as examples a case where two screw feeders 20 are used and a case where one screw feeder 20 is used. In this embodiment, a bentonite mixed soil consisting of gravel M1 and fine grain M2 as shown in FIG. 1(b) will be taken as an example of the backfill material M, but the backfill material M that can be manufactured by the backfill material manufacturing device MD is not limited to the above-mentioned bentonite mixed soil. Any backfill material M can be used as long as it can be manufactured by mixing and stirring large-diameter granular materials and small-diameter granular materials.

[0037] <<<<Backfilling material manufacturing equipment MD>>>> <<When using two screw feeders 20>> As shown in Figures 2(a) and (b), the backfilling material manufacturing equipment MD is equipped with two screw feeders 20 (an upper screw feeder 20a and a lower screw feeder 20b) and a hopper 30 installed on each screw feeder 20.

[0038] The screw feeder 20 is of an axial type and includes a shaft portion 21 and a screw blade 22 attached around the shaft portion 21. As shown in the plan view of Fig. 2(b), a motor 23 for rotating the shaft portion 21 is provided on one end side of the shaft portion 21, and the shaft portion 21 and the screw blade 22 are contained in a trough 24. A hopper 30 is installed on the side surface of one end of the trough 24 adjacent to the motor 23, and a discharge port 241 for discharging the material conveyed by the rotation of the shaft portion 21 and the screw blade 22 is provided on the other end side.

[0039] 2(a), the hopper 30 includes a hopper body 31 and an opening / closing gate 32 provided at a connection portion with the screw feeder 20. The opening degree of the connection portion can be adjusted by the opening / closing gate 32, thereby freely adjusting the amount of transported material supplied from the hopper body 31 to the screw feeder 20. The opening / closing gate 32 does not necessarily have to be of a sliding type as long as the opening degree can be adjusted.

[0040] Two screw feeders 20 equipped with hoppers 30 having such a configuration are arranged in parallel in the height direction with a gap therebetween, and each discharge port 241 is arranged at a different position in the axial direction. Also, a small diameter accommodating section 312 is formed in the hopper body 31 of the hopper 30 installed in the upper screw feeder 20a, and a large diameter accommodating section 311 is formed in the hopper body 31 of the hopper 30 installed in the lower screw feeder 20b.

[0041] As a result, when the motors 23 provided on each of the two screw feeders 20 are operated to operate the backfilling material manufacturing device MD, the fine grain fraction M2 transported to the upper screw feeder 20a and dropped from the discharge port 241 can be dropped toward the gravel fraction M1 transported to the lower screw feeder 20b and discharged from the discharge port 241. Then, the fine grain fraction M2 enters and fills the gaps in the gravel fraction M1, and a backfilling material M in which the gravel fraction M1 and the fine grain fraction M2 are uniformly mixed can be manufactured without mixing and stirring.

[0042] <<When using one screw feeder 20>> The backfilling material manufacturing device MD may be provided with only one screw feeder 20 provided with a hopper 30, as shown in Fig. 3. In this case, the configuration of the hopper 30 is different from that in the case where the above-mentioned two screw feeders 20 are used.

[0043] The hopper 30 comprises a hopper body 31 and opening / closing gates 32a, 32b, and a partition member 313 is erected inside the hopper body 31. This divides the inner space of the hopper body 31 into two, with a large diameter accommodating section 311 formed on one side and a small diameter accommodating section 312 formed on the other side. In addition, the opening / closing gates 32a, 32b provided at the connection between the hopper body 31 and the screw feeder 20 are linked together so that when one of the gates is opened, the other is closed.

[0044] Therefore, when the opening / closing gate 32a on the large diameter storage section 311 side and the opening / closing gate 32b on the small diameter storage section 312 side are alternately opened and closed while the backfilling material manufacturing device MD is in operation, the gravel portion M1 and the fine grain portion M2 are alternately transported to the screw feeder 20 and dropped from the discharge port 241. This allows the operation of dropping the fine grain portion M2, which has been transported to the screw feeder 20 and dropped from the discharge port 241, toward the gravel portion M1, which has been transported to the screw feeder 20 and dropped from the discharge port 241, to be continuously performed.

[0045] Then, the fine grain fraction M2 enters and fills the gaps in the gravel fraction M1, and the backfill material M in which the gravel fraction M1 and the fine grain fraction M2 are uniformly mixed can be produced without mixing and stirring. In addition, the opening degree of each of the opening / closing gates 32a, 32b is adjustable when the connection part is opened, and the supply amount of each of the gravel fraction M1 and the fine grain fraction M2 supplied to the screw feeder 20 can be freely adjusted.

[0046] As described above, each of the backfilling material manufacturing devices MD can manufacture the backfilling material M in the access tunnel 13 to which it is transported, simply by supplying the gravel portion M1 and the fine-grained portion M2 to the hopper 30. Therefore, it is possible to omit the process of manufacturing the backfilling material M in a plant or the like separately installed on-site, as is generally performed in backfilling construction.

[0047] In addition, by appropriately adjusting the opening of the opening / closing gates 32, 32a, and 32b, the supply amount of the gravel portion M1 and the fine grain portion M2 to the screw feeder 20 can be appropriately changed. This makes it possible to easily manufacture backfilling materials M with different compositions continuously without stopping the backfilling material manufacturing device MD.

[0048] <<Backfilling device BD>> As shown in Fig. 4, the backfilling device BD includes a traveling body 40 carrying the backfilling material manufacturing device MD, a material supply vehicle 50, a density evaluation means 60, and a protective plate 70. Fig. 4 shows an example in which the backfilling material manufacturing device MD having two screw feeders 20 is mounted on the traveling body 40.

[0049] The traveling body 40 is equipped with a backfilling device BD, and includes a vehicle body 42 equipped with crawlers 41, a slide base 43 slidably mounted on the upper surface of the vehicle body 42, and a support base 44 installed on the slide base 43. The support base 44 supports two screw feeders 20. In addition, a reaction force receiving member 45 is interposed between the rear side surface of the slide base 43 and the rising portion of the vehicle body 42. The reaction force receiving member 45 suppresses the screw feeder 20 from moving backward on the vehicle body 42 via the slide base 43.

[0050] The slide base 43 and the reaction force receiving member 45 function effectively when compacting the backfilling material M in the access tunnel 13. In other words, when the backfilling material M is continuously produced and discharged while the discharge port 241 of the screw feeder 20 is buried in the previously produced backfilling material M, the density of the backfilling material M in the access tunnel 13 increases. Furthermore, as the screw feeder 20 continues to discharge the backfilling material M, the screw feeder 20 exhibits a behavior of retreating via the slide base 43, but this is resisted by the vehicle body 42 equipped with the crawler 41 via the reaction force receiving member 45. As a result, the backfilling material M in the access tunnel 13 is pressed by the newly produced backfilling material M, so that the backfilling material M can be compacted.

[0051] The material supply vehicle 50 is positioned behind the screw feeder 20 and the running body 40, and is equipped with a soil bin 51, a bucket 52, and a fine grain separation bin 53, all of which are configured to move freely within the access tunnel 13 together with the running body 40.

[0052] The soil tank 51 contains gravel M1, and when it moves above the bucket 52, it drops the gravel M1 from its bottom toward the bucket 52. The bucket 52 is provided with a transport device 521 such as a screw conveyor, and the gravel M1 is dropped into the hopper 30 of the lower screw feeder 20b via the transport device 521. The fine particle separation tank 53 contains fine particle M2 and is provided with a transport device 531 such as a screw conveyor. As a result, the fine particle M2 is dropped into the hopper 30 of the upper screw feeder 20a via this transport device 531.

[0053] The density evaluation means 60 is equipment provided to evaluate the density of the backfill material M filling the access tunnel 13 and to prevent the screw feeder 20 from being overloaded and breaking down. Fig. 4 shows an example in which an RI density meter 62 is installed near the discharge outlet 241 of the lower screw feeder 20b. Fig. 3 shows an example in which a compression type load cell 61 is installed on the reaction force receiving member 45 of the traveling body 40 as the density evaluation means 60. The density evaluation means 60 will be described in detail later.

[0054] In such a backfilling device BD, as shown in Fig. 4, a protective plate 70 that blocks the cross section of the access tunnel 13 is provided on the traveling body 40, and prevents the backfilling material M filling the access tunnel 13 from collapsing and the fine particles M2 dropped from the upper screw feeder 20a from scattering. Note that the protective plate 70 does not necessarily have to be installed.

[0055] When backfilling work is carried out using the backfilling device BD equipped with the above-mentioned backfilling material manufacturing device MD, a series of work related to backfilling work with backfilling material can be covered, including the production of backfilling material, the transportation and filling into the access tunnel 13, compaction, and even as-built management. The procedure for backfilling the access tunnel 13 using the above-mentioned backfilling device BD will be described below.

[0056] <<<<How to backfill the cavity>>>> <<When using one screw feeder 20>> First, as shown in Fig. 5(a), a backfilling device BD is installed at a predetermined position in the access tunnel 13, and then the gravel portion M1 and the fine grain portion M2 are supplied from the material supply vehicle 50 to the large diameter storage section 311 and the small diameter storage section 312 of the hopper 30, and the screw feeder 20 is operated and the opening / closing gates 32a, 32b are alternately opened and closed. The time interval and opening degree of the opening / closing gates 32a, 32b are preset so that the gravel portion M1 and the fine grain portion M2 are alternately supplied to the screw feeder 20 in the designed blending amount.

[0057] Then, the gravel portion M1 and the fine grain portion M2 dropped into the large diameter storage portion 311 and the small diameter storage portion 312 of the hopper 30 are alternately supplied to the screw feeder 20 and continuously transported toward the discharge port 241. Then, when the gravel portion M1 and the fine grain portion M2 are alternately dropped from the discharge port 241 into the access tunnel 13, the backfill material M is continuously produced.

[0058] When backfill material M is continuously produced in the access tunnel 13, the discharge port 241 of the screw feeder 20 is buried in the backfill material M, as shown in Fig. 5(b). In this state, the gravel portion M1 and the fine grain portion M2 are continuously transported, and the access tunnel 13 is filled with the backfill material M while the density of the filled backfill material M is increased. As described above, when the density increases, the backfill material M filled in the access tunnel 13 is pressed by the newly produced backfill material M, and the backfill material M is gradually compacted.

[0059] In this way, the work of producing and filling the backfilling material M in the access tunnel 13 is carried out while evaluating the density of the backfilling material M by checking the output value acquired by the density evaluation means 60 against a preset evaluation criterion. The evaluation criterion is set for each density evaluation means 60 employed in correspondence with the desired density, and when the evaluation criterion is reached, the backfilling device BD is stopped, that is, the production of the backfilling material M is stopped. This makes it possible to compact the backfilling material M in the access tunnel 13 at the desired density, and also makes it possible to prevent the screw feeder 20 from being overloaded and breaking down.

[0060] 5(c), the backfilling device BD is retreated a predetermined distance by utilizing the traveling body 40, and the screw feeder 20 is pulled out from the backfilling material M. The above-mentioned work is repeated until the backfilling range planned for the access tunnel 13 is backfilled. This allows the backfilling material M compacted at a uniform density to be continuously provided in the longitudinal direction of the access tunnel 13, and a uniform finished shape can be achieved over the entire length of the backfilling range planned for the access tunnel 13.

[0061] On the other hand, if it is desired to produce backfilling material M by changing the mix of gravel M1 and fine grain M2 in accordance with changes in the properties of the surrounding rock mass in the middle of the planned backfilling range of the access tunnel 13, the time interval for alternately opening the opening gates 32a, 32b and the opening degree thereof are appropriately changed. This makes it possible to easily produce and fill the backfilling material M with a changed mix without interrupting the backfilling work.

[0062] <<When using two screw feeders 20>> First, as shown in Fig. 6(a), the backfilling device BD is installed at a predetermined position in the access tunnel 13, and then the screw feeder 20 is operated. Fine particles M2 are supplied from the material supply vehicle 50 to the hopper 30 of the upper screw feeder 20a, and gravel M1 is supplied to the hopper 30 of the lower screw feeder 20b, and the gates 32a and 32b are opened. The opening of the gates 32a and 32b is appropriately adjusted so that the gravel M1 and the fine particles M2 are supplied in a previously designed mixture.

[0063] 2(a), the fine grains M2 transported to the upper screw feeder 20a and dropped from the discharge port 241 enter the gaps in the gravel M1 transported to the lower screw feeder 20b and discharged from the discharge port 241, and the backfilling material M is continuously produced. After that, the access tunnel 13 is backfilled in the same manner as in the case of using two screw feeders 20.

[0064] That is, when the backfilling material M is continuously produced in the access tunnel 13, the discharge ports 241 of the two screw feeders 20 are buried in the backfilling material M as shown in FIG. 6(b). In this state, the work of producing and filling the backfilling material M in the access tunnel 13 is continued while evaluating the density of the backfilling material M. When the desired density is reached, the backfilling device BD is stopped, and the backfilling device BD is retreated a predetermined amount to pull out the screw feeder 20 from the backfilling material M as shown in FIG. 6(c). The above work is repeated until the backfilling range planned in the access tunnel 13 is backfilled. In addition, if it is desired to produce the backfilling material M by changing the mixture of the gravel portion M1 and the fine grain portion M2 in the middle of the backfilling range planned in the access tunnel 13, the opening degree of the opening / closing gate 32 in the hopper 30 having the large diameter storage section 311 or the small diameter storage section 312 is appropriately changed.

[0065] <<Evaluation means for evaluating density of backfill material M>> In the above-mentioned method for backfilling a cavity, a compression type load cell 61 provided on the reaction force receiving member 45 of the traveling body 40 is used as density evaluation means 60 for evaluating the density of the backfilling material M in Fig. 5. Also, in Fig. 6, an insertion type scattering type RI density meter 62 provided near the discharge port 241 of the screw feeder 20 is used. The compression type load cell 61 and the RI density meter 62 will be described below.

[0066] <When using a compression load cell (compression load)> The compression load cell 61 measures the load in the compression direction acting on the reaction force receiving member 45. As shown in Fig. 5(b), in the backfilling device BD, as the density of the backfilling material M increases in the access tunnel 13 and the screw feeder 20 continues to discharge the backfilling material M, the screw feeder 20 exhibits a behavior of retreating on the car body 42 via the slide base 43. This is resisted by the car body 42 equipped with the crawlers 41 via the reaction force receiving member 45.

[0067] Therefore, a compression load cell 61 is provided on the reaction force receiving member 45, and the load in the compression direction (retraction force) is measured to evaluate the density of the backfilling material M filling the access tunnel 13. The evaluation method involves determining in advance the load when the backfilling material M reaches a desired density, and setting this as the evaluation standard. Then, when the measurement value of the compression load cell 61 during backfilling work reaches the evaluation standard, the backfilling work is stopped.

[0068] <When using an RI density meter (scattered gamma ray count)> The insertion-type scattering type RI density meter 62 is used as a means for measuring soil density, and is attached at a position where it can be buried in the backfill material M filled in the access tunnel 13, such as near the discharge outlet 241 of the screw feeder 20, as shown in Figure 6(a).

[0069] As shown in FIG. 7, the RI density meter 62 is equipped with a gamma ray source unit 621 equipped with cesium 137 (Cs137) that emits gamma rays, and a detector 622, and is a device that detects the number of scattered gamma rays that are emitted from the gamma ray source unit 621, scattered in the backfilling material M, and then enter the detector 622. It is known that gamma rays are absorbed when the density of the passage is high. Therefore, as an evaluation method, a test is performed in advance and the output value of the RI density meter 62 corresponding to the density when the backfilling material M reaches the desired filling degree is set as the evaluation standard. Then, when the measured value of the RI density meter 62 reaches the evaluation standard during the backfilling work, the backfilling work is stopped.

[0070] The above-mentioned evaluation methods using the compression type load cell 61 and the RI density meter 62 are methods for directly evaluating the density of the backfilling material M. However, the present invention is not limited to these methods, and an indirect evaluation method may be adopted.

[0071] <<Estimation using load sensors>> For example, Fig. 8(a) shows an example in which a load sensor 63 such as a load cell is provided near the discharge port 241 of the screw feeder 20. The load sensor 63 is provided on the upper surface of the trough 24, within a range that is buried in the backfilling material M during backfilling work. There is no limitation on the number of sensors, but by installing multiple sensors in the axial direction of the screw feeder 20 and using the average or median of the output values ​​output from each sensor, a highly reliable output value can be obtained.

[0072] As a method for evaluating the density, a test is conducted in advance to confirm the relationship between the density of the backfilling material M and the output value of the load sensor 63, and the output value of the load sensor 63 when the backfilling material M reaches a desired density is set as an evaluation criterion. Then, when the output value of the load sensor 63 reaches the evaluation criterion during the backfilling work, the backfilling work is stopped.

[0073] <<Estimation using a laser displacement meter>> 8(b) shows an example in which a laser displacement meter 64 is provided on the screw feeder 20. The laser displacement meter 64 is provided on the upper surface of the trough 24, at a position separated from the area that will be buried in the backfilling material M during backfilling work. The laser displacement meter 64 irradiates a laser beam toward the surface of the backfilling material M and receives the reflected light, thereby making it possible to measure the distance from the laser displacement meter 64 to the surface of the backfilling material M in a non-contact manner.

[0074] Therefore, as a method for evaluating density, a test is performed in advance to obtain the distance from the laser displacement meter 64 to the surface of the backfilling material M when the backfilling material M reaches the desired density, and this is set as the evaluation standard. Then, when the output value of the laser displacement meter 64 reaches the evaluation standard during backfilling work, the backfilling work is stopped.

[0075] Incidentally, neither the output values ​​of the load sensor 63 nor the laser displacement meter 64 can directly evaluate the density of the backfilling material M. Therefore, by using the compression type load cell 61 or the RI density meter 62 in combination and evaluating the density together with their output values, it becomes possible to perform as-built management with higher accuracy.

[0076] As described above, according to the method for backfilling the cavity, it is possible to easily produce backfill material M consisting of a bentonite mixed soil in which dry gravel M1 and fine grains M2 are uniformly mixed, and it is also possible to use the produced backfill material M to backfill the access tunnel 13 uniformly and efficiently.

[0077] The backfilling material manufacturing method, the cavity backfilling method, the backfilling material manufacturing apparatus, and the backfilling apparatus of the present invention are not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0078] For example, in this embodiment, as shown in Fig. 2, in the backfilling material manufacturing device MD that conveys the gravel portion M1 and the fine grain portion M2 separately by two screw feeders 20, only one combination of the upper screw feeder 20a and the lower screw feeder 20b is provided. However, this is not limited to this, and a configuration having a plurality of these combinations may be used.

[0079] Similarly, for a backfilling material manufacturing device MD in which a single screw feeder 20 transports gravel M1 and fine grain M2 separately, as shown in Figure 3, it is also possible to prepare not just one but multiple screw feeders 20 and arrange them in parallel with some spacing between them.

[0080] Furthermore, in this embodiment, the method of filling the backfilling material M using the backfilling device BD is directly applied to the access tunnel 13, but this is not necessarily limited to this. For example, the access tunnel 13 may be backfilled by using other construction methods in combination, such as spraying bentonite mixed soil produced by adding water and adjusting it onto the wall surface of the access tunnel 13, or spreading it onto the bottom surface and compacting it, and then filling the gaps surrounded by these with the backfilling material M.

[0081] Furthermore, the cavity that is backfilled using the backfilling device BD is not limited to the access tunnel 13 in the high-level radioactive waste disposal site 10, but may be applied to any space.

[0082] In addition, in this embodiment, a shaft type is used as the screw feeder 2 of the backfilling material manufacturing device MD, but this is not limited to this, and a shaftless type may also be used. [Explanation of symbols]

[0083] 10. Disposal Site 11 Disposal tunnel 12 Access Tunnel 13 Access Tunnel 20 Screw feeder 20a Upper screw feeder 20b Lower screw feeder 21 Shaft 22 Screw blade 23 Motor 24 Trough 241 Outlet 30 Hopper 31 Hopper body 311 Large diameter housing 312 Small diameter storage section 313 Partitioning material 32 Opening and closing gate 32a Opening and closing gate 32b Opening and closing gate 40 Running body 41 Crawler 42 Body 43 Slide stand 44 Support stand 45 Reaction receiving member 50 Material supply vehicle 51 Earthen tank 52 Bucket 521 Transport Equipment 53 Fine grain separation tank 531 Transport Equipment 60 Density Assessment Methods 61 Compression Load Cell 62 RI density meter 621 γ-ray source section 622 Detector 63 Load Sensor 64 Laser Displacement Meter 70 Protective plate M Backfill material M1 Gravel (large granular material) M2 Fine particles (small diameter particles)

Claims

1. The large-diameter granules and the small-diameter granules are conveyed separately by a screw feeder. A method for producing backfilling material, comprising the steps of: filling gaps between the large-diameter granules dropped from the screw feeder with the small-diameter granules at the destination to produce backfilling material.

2. The method for producing a backfill material according to claim 1, The backfill material is a bentonite backfill material, A method for producing backfill material, characterized in that the large-diameter granules contain gravel and the small-diameter granules contain bentonite.

3. A method for filling a cavity in ground with the backfilling material manufactured by the method for manufacturing a backfilling material according to claim 1 or 2, comprising the steps of: conveying the large diameter granular material and the small diameter granular material toward the cavity; A method for backfilling a cavity, comprising the steps of producing the backfilling material in the cavity while filling the cavity.

4. The backfilling method according to claim 3, A backfilling method, comprising the steps of: continuously producing the backfilling material while burying the discharge port of the screw feeder in the previously produced backfilling material.

5. The backfilling method according to claim 3 or 4, Evaluating the density of the backfill material for the cavity; A backfilling method, comprising the steps of: stopping production of the backfilling material when a preset density is reached.

6. The backfilling method according to any one of claims 3 to 5, A backfilling method characterized in that the cavity is a tunnel at a waste disposal site.

7. A backfilling material manufacturing apparatus for use in the method for manufacturing a backfilling material according to claim 1 or 2, The screw feeder and a hopper are provided, A pair of storage sections for storing the large diameter granular material and the small diameter granular material are arranged on either side of a partition member provided inside the hopper, A backfilling material manufacturing apparatus characterized in that opening and closing gates which are alternately opened are provided at the bottoms of the pair of storage sections.

8. A backfilling material manufacturing apparatus for use in the method for manufacturing a backfilling material according to claim 1 or 2, The screw feeder and a hopper are provided, The screw feeders are arranged in parallel with a gap in the height direction, and each discharge port is arranged to be shifted in the axial direction, A small diameter storage section for storing the small diameter granular material is provided in the hopper provided in the screw feeder located above, A backfilling material manufacturing apparatus, characterized in that a large diameter storage section for storing the large diameter granular material is provided in the hopper equipped on the screw feeder located below.

9. A backfilling device for a cavity in the ground that fills the cavity with a backfilling material, The backfilling material manufacturing apparatus according to claim 7 or 8, An evaluation means for evaluating the density of the backfilling material filled in the cavity; A backfilling device comprising:

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