JP2017198584A - Method for permeability test for water shut-off material and device for providing test piece for permeability test - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a quantitative evaluation of the coefficient of permeability of a water shut-off material such as a vertical water shut-off material, on the basis of the followability to an aperture.SOLUTION: There is provided a method for a permeability test which considers the deformation followability of a water shut-off material, the method including the steps of: preparing a test piece obtained by filling a water shut-off material into a mold while a space holding material is being arranged in the mold; and removing the space holding material from the test piece and then running a permeability test.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a water permeability test method and a test body providing apparatus for a water permeability test in consideration of deformation followability of a water stop material used for a water stop wall or the like.

The deformation follow-up property in high-density bentonite mixed soil used as a water shielding material for radioactive waste disposal facilities and waste disposal sites has been confirmed by shear permeability tests.
Examples thereof are shown in Non-Patent Documents 1 and 2 below.
As described in Non-Patent Documents 1 and 2, in conventional research, bentonite mixed soil is compacted in an unsaturated state, and after that, a high swelling pressure is generated in the bentonite mixed soil by submergence. Looking for.

However, since the water-stopping material used as the vertical water-blocking material is cast by being pumped in a state of being mixed with water, the swelling pressure due to the flooding after the casting cannot be expected. is there.
Therefore, in order to grasp the water permeability of the water-stopping material used as the vertical water-blocking material, the water-stopping material does not take into account the swelling pressure and the wall such as the sheet pile or PC wall does not have to be swollen. Following the deformation, it is necessary to consider whether water shielding is ensured.

However, as described above, the conventional shear permeability test method has a problem that refilling of the space caused by deformation cannot be considered.
Similarly, in the case of an EC wall construction method using a bentonite-based vertical water shielding material, it has high durability (deformability followability) by confirming that shear fracture does not occur based on the uniaxial compression test result. As a result, it has not yet been possible to evaluate the deformation followability with respect to the opening of the filling space due to deformation.

Kudo et al., Ca-type bentonite shear permeability test and elongation strain follow-up test No. 1 The 67th Annual Conference of Japan Society of Civil Engineers, 2012 Motoyama et al., Performance Evaluation of Saturated Compressed Bentonite by Single-Shear Test and Permeability Test, 64th Annual Scientific Lecture, Japan Society of Civil Engineers, 2009

As described above, the conventional techniques described above have the following problems.
(1) It is impossible to quantitatively evaluate the permeability coefficient considering the followability to the mesh.
(2) It is impossible to grasp the period from when the mesh opening occurs until the water shielding is restored.

An object of the present invention is to provide a means that enables quantitative evaluation of a water permeability coefficient in consideration of followability to an opening of a water blocking material such as a vertical water shielding material.

The first invention of the present application, which has been made to solve the above-mentioned problems, is a water permeation test method in consideration of deformation followability of a water-stopping material, in which the water-stopping material is filled in a state in which a spacing member is disposed inside the mold. A test body is prepared, and the water permeability test is performed after removing the spacing member from the test body.
The second invention of the present application is characterized in that, in the first invention, the spacing member is made of a material that can be dissolved or melted.
The third invention of the present application is characterized in that, in the second invention, the spacing member is a salt paste.
The fourth invention of the present application is a test body providing apparatus for forming a test body used for a water permeability test of a water-stopping material, the mold having a water-filling material filling space, and disposed in the filling space And the space | interval holding material for forming the space which is not filled with a water stop material in a part in this filling space was provided at least.

According to the present invention, the following effects can be obtained.
(1) It is possible to quantitatively evaluate the permeability coefficient in consideration of the followability to the mesh opening generated in the vertical water shielding material.
(2) By following the change of the water permeability coefficient over time after the opening of the mesh occurs, it is possible to grasp the period of water-impervious recovery due to deformation followability.

Schematic which shows the whole structure of the test body provision apparatus which concerns on this invention. The schematic sectional drawing which shows the example of a space | interval holding material. Schematic which shows the example of a compaction apparatus and a soil pressure apparatus. Schematic which shows the experimental result of a water permeability test.

  Embodiments of the present invention will be described below with reference to the drawings.

<1> Overall Configuration A test specimen providing apparatus used in the water permeability test method according to the present invention will be described.
The specimen providing device A according to the present invention includes at least a mold 10 that can be filled with a water-stopping material and a spacing member 20 that is disposed in the mold 10.
A water permeability test is performed by combining this test body providing apparatus A and a water permeation apparatus (not shown) that is connected to the test body providing apparatus A and controls the flow of water into and out of the test body.

<2> Mold The mold 10 is a member for filling a water-stopping material inside.
What is necessary is just to determine the dimension and shape of the mold 10 suitably according to the standard of the water permeability test to implement.
In this embodiment, the mold 10 has a shape having flanges on the upper and lower sides of a cylindrical member whose upper and lower ends are opened, and the inside thereof is used as a filling space 11 of a water-stopping material. It is preferable at the point which can visually recognize the followability of the water stop material with respect to the space | gap after removing the space | interval holding material 20 to do.

<2.1> Water-stopping material The water-stopping material filled in the mold generally includes all materials used for water-stopping purposes.
In the present embodiment, bentonite mixed soil is assumed in which bentonite is the main material for the waterstop material.

<3> Interval Holding Material The interval holding material 20 is a member for forming a space that is not filled with the water-stopping material by being placed in the mold 10.
The spacing member 20 can be removed from the mold 10 before the start of the water permeability test, so that a gap (a space not filled with the water-stopping material) can be provided in the filling space 11.
By considering this gap as an opening portion consisting of cracks or the like caused by deformation of the water blocking wall, the water shielding property when the opening occurs, the followability of the water blocking material to the opening, The recovery period can be grasped.
Therefore, the dimension and shape of the spacing member 20 are determined in accordance with the condition of the opening amount in the water permeability test to be performed.

<3.1> Material of Interval Holding Material FIG. 2 shows a configuration example of the interval holding material.
The spacing member 20 may be formed of a material having a fixed shape such as wood, plastic, or steel, or may be formed of a member that disappears in a state of being disposed in the mold 10. As the vanishing member, ice melting at room temperature, water-soluble salt, sugar, alum and the like can be used.
For example, in FIG. 2 (a), the shaped material 20 a is arranged in the approximate center of the filling space 11.
Moreover, in FIG.2 (b), what added the water | moisture content to the salt and paste-like (salt paste 10b) is apply | coated to the inner peripheral surface of the mold 10 by predetermined thickness.
Moreover, in FIG.2 (c), the ice 20c is formed in a part of filling space.
As a method of constructing the spacing member 20 made of ice 20c, a method of cooling in a state in which a part of the filling space 11 of the mold 10 is filled with water is conceivable.

<4> Other Test Apparatus An example of another test apparatus is shown in FIG.
These devices can be used as appropriate to set conditions for the water permeability test to be performed.

<4.1> Consolidation device The consolidation device is a device for compacting the water-stopping material filled in the mold.
As shown in FIG. 3A, the compacting device 0 is connected to the upper part of the mold 10 and is slidable in the vertical direction in the guide tube 31 communicating with the filling space 11 of the mold. The pressing plate 32 capable of pressing the water-stopping material B in the filling space 11 can be configured.

<4.2> Earth pressure device The earth pressure device 40 is a device for reproducing the earth pressure caused by the depth of the ground with a test specimen during a water permeability test.
As shown in FIG. 3B, the earth pressure device can be constituted by a weight 41 or the like that can press the water-stopping material B in the mold 10 from information.

<5> Usage example A procedure example of a water permeability test using the test specimen providing apparatus A is as follows.
(1) Installation of spacing members (Figs. 1 and 2)
A test specimen providing apparatus A in which a spacing member 20 is arranged in the mold 10 is prepared.
(2) Filling of sample The water-stopping material B is placed in the filling space 11 in the mold 10.
(3) Condition setting (Fig. 3)
As necessary, a consolidation work of the water-stopping material B and a load work of earth pressure are performed so as to match the experimental conditions of the water permeability test.
(4) Water permeability test / removal of spacing member When the test body is completed, a permeability test is started, the spacing material 20 is removed as appropriate, and the change in the permeability coefficient is measured.
The water permeability test may be started after the spacing member 20 is removed.

<6> Test result The test result of the water permeation test using the specimen providing device A according to the present invention will be described.
As the opening phenomenon of the PC wall, there are two types of phenomenon, a phenomenon in which only one wall is deformed and a phenomenon in which the PC wall on both sides is deformed. Two types of patterns with different thicknesses of the holding material 20 were created.
In addition, it is known from analysis that the volume strain caused by the opening of the actual PC wall is about εv = 3%, so in this test, the volume strain εv = 5% is generated in consideration of the margin. A salt paste was applied as the spacing member 20 to the inner peripheral surface of the mold 10.
The mold 10 was prepared with an inner diameter of 10 cm and a height of 2 cm, and with both side deformations having an inner diameter of 10 cm and a height of 5 cm.
In a test performed with a mold with a height of 5 cm on both sides, the change in hydraulic conductivity due to the loading pressure was also measured.

4A and 4B are diagrams showing the relationship between the number of trials of the water permeability test and the water permeability coefficient, where FIG. 4A is a one-side deformation at a mold height of 2 cm, and FIG. , (C) shows the state when the mold is deformed on both sides at a height of 5 cm.
In the case of the one-side deformation shown in FIG. 4 (a), water passes through the salt paste at the start of the test, so the water permeability coefficient is a very large value, but the water permeability coefficient gradually decreases, and a constant space It was found that the filling effect was demonstrated.
On the other hand, in the case of the both-side deformation shown in FIG. 4B, the salt paste is as thin as 1.2 mm, so the water permeability coefficient at the start of the test is small compared to the one-side deformation, but the water permeability coefficient gradually decreases. . However, as the number of trials was increased, it was found that the hydraulic conductivity tends to increase. It seems that the fine particles of the slurry as the water-stopping material B were gradually scoured by passing water.
Moreover, in FIG.4 (c), a water permeability coefficient falls gradually from the time of a test start, and the tendency which starts to raise after that is the same as that of 4 (b). After that, the hydraulic conductivity decreased by loading the upper load. This is considered that the slurry which is the water-stopping material B volume-expanded laterally and filled the space due to the loading of the overload.

<7> Actions / Effects As described above, according to the present invention, by removing the spacing member 20 provided in the mold 10, it is possible to reproduce openings such as cracks due to deformation of the water blocking wall. Whether or not the water-stopping material follows the opening and recovers the water barrier property can be quantitatively evaluated by the change in the measured water permeability coefficient or the visual recognition inside the mold.

A Specimen providing device B Water stop material 10 Mold 11 Filling space 20 Spacing material 20a Shaped material 20b Salt paste 20c Ice 30 Consolidation device 31 Guide tube 32 Press plate 40 Earth pressure device 40a Weight

Claims (4)

A water permeability test method taking into account the deformation followability of the water stop material,
Prepare a test body that is filled with a water-stopping material in the state where a spacing material is placed inside the mold,
A water permeability test is performed after removing the spacing member from the test body,
Water permeability test method for water-stop materials. The spacing member is made of a material that can be dissolved or melted,
The water permeability test method for the water stop material according to claim 1. The spacing member is a salt paste,
The water permeability test method for the water stop material according to claim 2. A test body providing apparatus for forming a test body for use in a water permeability test of a water-stopping material,
A mold having a space for filling a water-stopping material;
It is disposed in the filling space, and has at least a gap maintaining material for forming a space in which part of the filling space is not filled with a water stop material,
Specimen providing device for water permeability test.

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