JP3829588B2 - Water absorption management method for swellable materials when constructing a waste disposal site - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water absorption management method for a swellable material at the time of constructing a waste disposal site.
[0002]
[Prior art]
Industrial waste has a wide variety of properties, and various disposal methods exist depending on the properties and are put into practical use. Among these, radioactive waste disposal sites, for example, have a method of forming a hollow portion in the underground bedrock and storing the radioactive waste stored in a container container inside the hollow portion. In the field, high air permeability that allows gas generated from waste to pass through safely and low water permeability that can prevent the ingress of groundwater are required.
[0003]
As a construction method of a radioactive waste disposal site that responds to such demands, a barrier layer made of a swellable material compacted with bentonite is formed on the inner surface side of the cavity, and concrete is contained inside this barrier layer. A method for constructing a structure has been proposed.
[0004]
However, the construction method for such a disposal site, particularly when groundwater is present in the planned construction site of the disposal site, is technically explained below regarding the water absorption management of the swellable material at the time of construction. There was a problem.
[0005]
[Problems to be solved by the invention]
That is, when a cavity is formed in the underground bedrock, a barrier layer made of a swellable material is formed inside the cavity, and then a concrete structure for storing and storing radioactive waste is constructed, it is disposed of from the formation of the barrier layer. It takes a long time to complete the construction of the venue.
[0006]
However, if groundwater exists in the underground rock in such a state, the swellable material that forms the barrier layer partially absorbs the groundwater and becomes partially swelled, ensuring the required quality. There is a problem that it is difficult to do and affects the construction of concrete structures.
[0007]
The present invention has been made in view of such conventional problems, and its object is to control the water absorption of the swellable material, thereby ensuring the required quality and the ease of construction. The object is to provide a water absorption management method for a swellable material at the time of construction of a waste disposal site that can be secured.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a concrete structure in which a hollow portion is formed in a rock, a barrier layer made of a swellable material is provided along the inner surface of the hollow portion, and the barrier layer is formed inside the barrier layer. In the water absorption management method for swellable materials at the time of construction of a waste disposal site that contains and stores radioactive waste in the materials,
During or before the formation of the barrier layer, a drain hole for controlling the groundwater supplied to the barrier layer is formed by excavation at a predetermined interval outside the barrier layer, and water is collected in the drain hole. The drained water was drained to the outside when the groundwater level exceeded the specified level .
According to the management method of the swellable material at the time of constructing the radioactive waste disposal site configured as described above, the barrier layer is formed at a predetermined interval outside the barrier layer during or before the formation of the barrier layer. The drainage for control of the groundwater supplied is excavated and groundwater collected in the drainage hole is drained to the outside when the water level exceeds a predetermined level. By adjusting the amount of the swellable material, it becomes possible to prevent deformation of the swellable material due to excessive water pressure and partial swelling due to partial water absorption.
The hollow portion may be formed in a shaft shape in the rock, and a plurality of the drain holes may be arranged at a predetermined interval in the circumferential direction so as to surround the outer periphery of the barrier layer.
The hollow portion is formed in an elongated shape along the axial direction of the tunnel in an invert portion of a tunnel excavated in the rock, and the drainage holes are formed on both sides along the outer periphery of the barrier layer. It can be formed in a groove shape.
In addition, after the construction of the disposal site is completed, the groundwater control drainage hole can be used, for example, for detection of discharge of harmful substances from the disposal site, and when unnecessary, a swellable material, for example, It may be blocked by filling with bentonite, a mixture of bentonite and sand, water-absorbing polymer resin or the like.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. 1 and 2 show an embodiment of a water absorption management method for a swellable material when constructing a waste disposal site according to the present invention.
[0010]
The water absorption management method shown in these figures is an application example in the case of constructing the waste disposal site 10 whose completed state is shown in FIG. The waste disposal site 10 shown in FIG. 2 is a type in which a shaft-like cavity 13 is formed in the basement of the rock 12, and a barrier layer 14 made of a swellable material and a concrete structure 16 are provided. I have.
[0011]
The barrier layer 14 is formed by compacting a swellable material such as calcium or sodium bentonite to a predetermined thickness, having a water permeability of 10 ⁻⁹ to 10 ⁻¹⁰ cm / sec or less and an air permeability of 10 ^−. it becomes about ⁷ cm / sec, perforated and disc-like bottom 140, a cylindrical side wall portion 141 in which the upper end is open, and a disk-shaped upper plate portion 142 that closes the upper end opening of the side wall portion 141 is doing.
[0012]
The concrete structure 16 contains therein radioactive waste sealed in a container container or the like. The concrete structure 16 is inside the swellable barrier layer 14 and has a disk-shaped bottom plate 160 and an upper end opened. The cylindrical side wall 161 and the disk-shaped upper plate 162 that closes the upper end opening of the side wall 161 are provided.
[0013]
When constructing the waste disposal site 10 configured as described above, first, a cylindrical hollow portion 13 is excavated and formed in a rock 12 to a required depth.
[0014]
When the cavity portion 13 is formed, the bottom portion 140 and the side wall portion 141 of the barrier layer 14 made of a swellable material are formed with a predetermined thickness along the bottom surface 130 and the side surface 131 by compacting bentonite or the like.
[0015]
When the formation of the bottom 140 and the side wall 141 of the barrier layer 14 is completed, the concrete structure 16 is formed inside the barrier layer 14. When forming the concrete structure 16, first, the bottom plate 160 is formed on the bottom 140 of the barrier layer 14 with a predetermined thickness.
[0016]
When the formation of the bottom plate 160 is completed, the side wall 161 is integrally formed on the upper portion of the outer peripheral side of the bottom plate 160. The side wall 161 is formed from the bottom to the top so that the inner surface of the side wall portion 141 of the barrier layer 14 and the outer surface thereof are in contact with each other.
[0017]
When the bottom plate 160 and the side wall 161 of the concrete structure 16 are formed, radioactive waste is accommodated therein, and thereafter, an upper plate 162 of the concrete structure 16 is formed, and the inside of the structure 16 is sealed. After that, the upper plate portion 142 of the barrier layer 14 is formed on the upper plate 162 so as to be continuous with the side wall portion 141, thereby completing the construction of the waste disposal site 10.
[0018]
The construction method of the waste disposal site 10 constructed by the above-described process is substantially the same as the conventional construction method of this type, but in the case of this embodiment, it is remarkable in the points described below. There are features.
[0019]
That is, in the waste disposal site 10 constructed in the above-described process, the cavity portion 13 is formed in the rock 12, and thereafter, the bottom portion 140 and the side wall portion 141 of the barrier layer 14 made of the swellable material are formed into the cavity. It is formed so as to contact the bottom surface 130 and the side surface 131 of the portion 13.
[0020]
However, in such a formation state, when groundwater is carried in the rock 12, this is supplied from the inner surface of the cavity 13 to the bottom 140 and the side wall 141 of the barrier layer 14 made of a swellable material. The
[0021]
If such a groundwater supply state is continued until the construction of the waste disposal site 10 is completed after the bottom 140 and the side wall 141 of the barrier layer 14 are formed, the period until completion is relatively long. The swellable material of the barrier layer 14 is in an excessively swollen state, making it difficult to ensure the required quality and affecting the construction of the concrete structure.
[0022]
Therefore, in this embodiment, in order to control the supply of groundwater to the swellable material, the groundwater control drain holes 20 are arranged outside the barrier layer 14 at a predetermined interval.
[0023]
In the case of the present embodiment, the control drain hole 20 surrounds the outer periphery of the side wall portion 141 of the barrier layer 14 formed in a ring shape having a predetermined thickness, and is spaced at a predetermined interval in the circumferential direction. A plurality of them are arranged at equiangular intervals.
[0024]
Each control drain hole 20 is drilled to a depth deeper than the bottom surface of the bottom 140 of the barrier layer 14 by boring, and inside each control drain hole 20 is a water level meter for detecting the level of collected groundwater. Based on the detection signal of the water level gauge, a submersible pump provided with a drain pipe for discharging the collected ground water to the outside when the ground water level exceeds a predetermined level is installed.
[0025]
Such a control drain hole 20 can be installed, for example, before excavation of the cavity 13 to eliminate groundwater that affects construction when the cavity 13 is formed, and the amount of groundwater is small. In some cases, excavation is performed before or during the formation of the barrier layer 14 to control the amount of groundwater supplied to the barrier layer 14.
[0026]
Now, according to the water absorption management method of the swellable material at the time of constructing the waste disposal site 10 configured as described above, a predetermined interval is provided outside the barrier layer 14 during or before the formation of the barrier layer 14. Separately, the drainage 20 for controlling the groundwater supplied to the barrier layer 14 is formed by excavation, and the groundwater collected in the drainage hole 20 is drained to the outside as necessary. The amount of groundwater absorbed by the swellable material for forming the barrier layer 14 can be adjusted to prevent excessive water absorption of the swellable material.
[0027]
As a result, according to the water absorption management method of the present embodiment, the ease of construction can be ensured while ensuring the required quality of the disposal site 10.
[0028]
In the above embodiment, the case where the present invention is applied to the disposal site 10 having a circular plane cross section is exemplified. However, the implementation of the present invention is not limited to this, and the disposal site has various shapes such as polygons. Can be applied to.
[0029]
3 and 4 show a second embodiment of the water absorption management method for a swellable material at the time of constructing a waste disposal site according to the present invention. Will be omitted, and only the characteristic points will be described below.
[0030]
The embodiment shown in these figures is an example applied when constructing the disposal site 10 a in the tunnel 22 excavated in the rock 12, and the disposal site 10 a is provided in the invert part of the tunnel 22. Yes.
[0031]
The disposal site 10a of the present embodiment is formed in a long shape along the longitudinal axis direction of the tunnel 22, a barrier layer 14a formed of a swellable material, and a concrete structure formed in the barrier layer 14a. Part 16a.
[0032]
The cavity 13a for constructing the disposal site 10a is excavated to a predetermined depth along the longitudinal axis of the tunnel 22, and the barrier layer 14a has a bottom part 140a, a side wall part 141a, and an upper plate part 142a. ing.
[0033]
The concrete structure portion 16a in which the waste is accommodated includes a bottom plate 160a, a side wall 161a, and an upper plate 162a, and is arranged in a line at a predetermined interval along the longitudinal axis direction of the tunnel 22.
[0034]
A partition wall portion 163 a of the barrier layer 14 is provided between the concrete structure portions 16 a adjacent to each other along the longitudinal axis direction of the tunnel 22. The configuration of the disposal site 10a as described above is substantially the same as this type of conventional one. However, in the case of the present embodiment, there are remarkable features in the points described below.
[0035]
That is, in the disposal site 10a of the present embodiment, a pair of groundwater control drain holes 20a are provided outside the barrier layer 14 at a predetermined interval along the outer periphery thereof.
[0036]
The control drain hole 20a of this embodiment is formed in a groove shape extending in the longitudinal axis direction of the tunnel 22 along the barrier layer 14a. In addition, a water level meter, a submersible pump, and the like are installed in the control drain hole 20a as in the above embodiment, and when the groundwater collected in the drain hole 20a exceeds a certain level, To the outside.
[0037]
Such a drain hole 20a for groundwater control is formed by excavation at a predetermined interval outside the barrier layer 14 during or before the formation of the barrier layer 14 as in the above embodiment.
[0038]
Then, if the groundwater collected in the drain hole 20a is drained to the outside as necessary, the amount of groundwater absorbed by the swellable material for forming the barrier layer 14 is adjusted during the construction of the disposal site 10a. Thus, it becomes possible to prevent excessive water absorption of the swellable material.
[0039]
【The invention's effect】
As described above in detail, according to the water absorption management method of the swellable material at the time of constructing the waste disposal site according to the present invention, by controlling the water absorption of the swellable material, the construction is performed while ensuring the required quality. Can be secured.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example of a radioactive waste disposal site to which a water absorption management method for a swellable material according to the present invention is applied.
FIG. 2 is a top view of FIG.
FIG. 3 is an explanatory plan view illustrating another example of a waste disposal site to which the water absorption management method for a swellable material according to the present invention is applied.
4 is a longitudinal sectional view of a main part of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Waste disposal site 12 Rock bed 13 Cavity part 14, 14a Swellable barrier layer 140 Bottom part 141 Side wall part 142 Upper plate part 16, 16a Concrete structure 160 Bottom plate 161 Side wall 162 Upper plate 20, 20a Drain hole 22 Tunnel

Claims (3)

Waste that forms a cavity in the bedrock, a barrier layer made of a swellable material is provided along the inner surface of the cavity, and contains and stores radioactive waste in a concrete structure formed inside the barrier layer In the water absorption management method of the swellable material at the time of construction of the disposal site,
During or before the formation of the barrier layer, a drain hole for controlling the groundwater supplied to the barrier layer is formed by excavation at a predetermined interval outside the barrier layer, and water is collected in the drain hole. A method for managing the water absorption of a swellable material at the time of construction of a waste disposal site, characterized in that the groundwater discharged is discharged to the outside when the water level exceeds a predetermined level .   The hollow portion is formed in a shaft shape in the rock, and a plurality of the drain holes are arranged at predetermined intervals in the circumferential direction so as to surround the outer periphery of the barrier layer. Item 5. A method for managing water absorption of a swellable material at the time of constructing the waste disposal site according to item 1.   The hollow portion is formed in an elongated shape along the axial direction of the tunnel in an invert portion of a tunnel excavated in the rock, and the drainage holes are formed on both sides along the outer periphery of the barrier layer. It forms in groove shape, The water absorption management method of the swelling material at the time of construction of the waste disposal site of Claim 1 characterized by the above-mentioned.

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