Perforated plate for water permeability test, water permeability test device, and water permeability test method

Abstract

An object of the present invention is to solve the problems of the related art, that is, to provide a perforated plate in which water passage holes can be freely added regardless of the position of a water injection and drainage groove of a flange, a water permeability test device including the perforated plate, and a water permeability test method using the water permeability test device.SOLUTION: This perforated plate for the water permeability test is used for the water permeability test, and has a Sototsutsumi part, a low surface part and a plurality of water permeable holes. The Sototsutsumi part is formed on the outer periphery of the front face, the low face part is formed on the whole or a part of the inner face part surrounded by the Sototsutsumi part, and the water passing hole is formed on the low face part. In a cross-sectional view, the low surface portion is formed at a position lower than the Sototsutsumi portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology related to permeability testing for measuring the permeability coefficient of soil and the like, and more specifically to a perforated plate and permeability testing device for permeability testing that can infiltrate a large amount of water into a test piece with a particularly small permeability coefficient, and a permeability testing method using this permeability testing device. [Background technology]

[0002] Because of its low permeability, bentonite is sometimes used as a cover soil mixture to seal buried objects, particularly as cover soil for shallow pit disposal. Shallow pit disposal is a method of disposing of waste with relatively low levels of radioactivity, in which the waste is stored and buried in a concrete pit constructed at a shallow depth from the ground surface. Bentonite-mixed soil is sometimes placed around the concrete pit containing the waste to reduce the advection rate of groundwater, etc.

[0003] Because of its low permeability, bentonite is sometimes used as a water-blocking material. In such cases, it is extremely useful to know the permeability of the bentonite beforehand, and therefore tests are sometimes conducted to measure the permeability coefficient of bentonite.

[0004] The most common method for determining the permeability of soil materials is through permeability tests. These tests are broadly divided into constant-head permeability tests, which are used for specimens with a relatively high permeability, and variable-head permeability tests, which are used for specimens with a relatively low permeability. Both tests use Darcy's law to calculate the permeability based on the cross-sectional area A and length L of the specimen, the water level difference h, and the amount of water supplied Q.

[0005] When conducting a constant head permeability test or a variable head permeability test, it is common to place perforated plates above and below the test specimen. These perforated plates have the function of supplying water into the test specimen and discharging water from the test specimen while preventing the test specimen from flowing out. For example, Patent Document 1 proposes a permeability test (constant head permeability test) in which the permeability coefficient of the test specimen is measured while controlling the pressure state of the test specimen, and also shows an example in which perforated plates are placed above and below the test specimen. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-120979 Summary of the Invention [Problem to be solved by the invention]

[0007] A flange FL shown in Figure 9(a) is sometimes used to supply and drain water through a perforated plate. This flange FL is a plate-like member with "inlet and outlet holes IH" that penetrate through the plate in the thickness direction. One side of the flange FL (hereafter referred to as the "front surface" for convenience) is also provided with an "inlet and outlet groove WG" that communicates with the inlet and outlet holes IH, and an O-ring RS may be placed therein as a sealing material (so-called packing).

[0008] When using a flange FL to supply water to a test specimen, the flange FL is placed on the top surface of the perforated plate HB, as shown in Figure 10(a). In other words, water supplied from the inlet / outlet holes IH of the flange FL is supplied to the water passage holes PH of the perforated plate HB through the inlet / outlet grooves WG, and the water that passes through the water passage holes PH permeates the test specimen. Therefore, the water passage holes PH are placed in a position corresponding to the inlet / outlet holes IH and the inlet / outlet grooves WG of the flange FL, as shown in Figure 9(b). Note that in Figure 9(b), the center line of the inlet / outlet grooves WG is shown with a dashed line. By placing the water passage holes PH in this way, water is supplied to the water passage holes PH through the inlet / outlet grooves WG, as shown in Figure 10(a).

[0009] When soil materials are used as specimens, their high hydraulic conductivity means that there is no need to infiltrate a large amount of water into the soil material. Therefore, the number of water holes PH provided in the perforated plate HB does not need to be very large (for example, as shown in Figure 9(b)). In contrast, when materials with low hydraulic conductivity, such as bentonite, are used as specimens, more water needs to be infiltrated into the specimen. However, even if water holes PH are provided at positions away from the inlet and drainage channels WG, as shown in Figure 10(b), water will not be supplied from the inlet and drainage channels WG to those water holes PH. Therefore, in order to infiltrate a large amount of water into the specimen, water holes PH must be provided at positions corresponding to the inlet and drainage channels WG, but the number that can be added under such restrictions is extremely limited.

[0010] In recent years, there has been a demand for non-destructive observation of the saturation state inside test specimens, and opportunities to perform measurements using X-ray CT (Computed Tomography) before and after permeability tests have been increasing. To perform X-ray CT measurements without disturbing the test specimen as much as possible, it is desirable to perform the measurements on the entire test equipment, including the test specimen. X-rays have the property of being unable to pass through materials with a high specific gravity, and when such materials are used, unwanted shadows are more likely to be cast.

[0011] Conventionally, metal or ceramic perforated plates have been used as perforated plates. Of these, metal perforated plates have a significant adverse effect on X-ray CT measurement, as described above. On the other hand, ceramic perforated plates have a limited effect on X-ray CT measurement, but their strength is low and they may break if the area becomes large, making them unsuitable for repeated use. Therefore, there has been a demand for perforated plates that have a negligible effect on X-ray CT measurement and yet have considerable strength.

[0012] The object of the present invention is to solve the problems of the prior art, that is, to provide a perforated plate that allows the addition of water holes freely regardless of the position of the inlet and outlet grooves of the flange, a permeability testing device equipped with the perforated plate, and a permeability testing method using the permeability testing device. [Means for solving the problem]

[0013] The present invention is based on the unprecedented idea of ​​forming an outer bank portion and a lower surface portion lower than the outer bank portion in a perforated plate, and supplying water from an inlet / outlet groove into the space provided between the lower surface portion and the flange surface.

[0014] The perforated plate for permeability testing of the present invention is a perforated plate used in permeability testing, and is provided with an outer bank portion, a bottom portion, and a plurality of water passage holes. The outer bank portion is formed on the outer periphery of the surface, and the bottom portion is formed on all or part of the inner surface portion of the surface surrounded by the outer bank portion, and the water passage holes are formed in the bottom portion. When viewed in cross section, the bottom portion is formed at a lower position than the outer bank portion.

[0015] The perforated plate for water permeability testing of the present invention may have a lower surface formed in the shape of one or more annular grooves.

[0016] The permeability test apparatus of the present invention is an apparatus used for permeability tests, and includes a cylindrical container for containing a test specimen, a perforated plate for permeability tests of the present invention, a flange, and a connecting member. The flange has an inlet / outlet groove formed on its surface and has inlet / outlet holes communicating with the inlet / outlet groove. The perforated plate for permeability tests is placed on the upper surface of the container containing the test specimen so that its surface faces upward, and the perforated plate for permeability tests is placed on the lower surface of the container so that its surface faces downward. Furthermore, a flange is placed on the upper surface of the perforated plate for permeability tests placed on the upper surface of the container so that its surface faces downward, and a flange is placed on the lower surface of the perforated plate for permeability tests placed on the lower surface of the container so that its surface faces upward. The upper and lower flanges then clamp the container and the upper and lower perforated plates for permeability tests, and the connecting member fastens the upper and lower flanges together. In addition, one or more of the multiple water passage holes are positioned so as not to face the inlet / outlet groove when the perforated plate for the permeability test and the flange are positioned opposite each other.

[0017] The water permeability test device of the present invention may also be one that includes an acrylic container and a perforated plate for water permeability testing, and a flange made of polyvinyl chloride.

[0018] The permeability test device of the present invention is a device used for permeability tests, and can also be one that includes an acrylic container, a perforated plate for permeability tests, and flanges and connecting members made of polyvinyl chloride.

[0019] The permeability test method of the present invention is a method for measuring the permeability coefficient of a test specimen using the permeability test apparatus of the present invention, and includes a bottom-side placement step, a test specimen accommodation step, a top-side placement step, and a flange fastening step. In the bottom-side placement step, a flange is placed with its surface facing up, and a perforated permeability test plate is placed on the top surface of the flange with its surface facing down. In the test specimen accommodation step, a container is placed on the top surface of the perforated permeability test plate placed on the top surface of the flange, and the test specimen is accommodated in the container. In the top-side placement step, a perforated permeability test plate is placed on the top surface of the container containing the test specimen with its surface facing up, and a flange is placed on the top surface of the perforated permeability test plate with its surface facing down. In the flange fastening step, the upper and lower flanges are fastened together with a connecting member while sandwiching the container and the upper and lower perforated permeability test plates. Then, water is poured into the inlet and outlet groove of the lower flange, passes through the water passage holes in the lower perforated plate for the permeability test, the test specimen contained in the container, and the water passage holes in the upper perforated plate for the permeability test, and is then drained out through the inlet and outlet groove of the upper flange, and the permeability coefficient of the test specimen can be determined based on the results. [Effects of the Invention]

[0020] The perforated plate for permeability testing, the permeability testing device, and the permeability testing method have the following effects. (1) Compared to conventional perforated plates, the number of holes can be increased freely. As a result, permeability tests can be conducted relatively easily even on specimens with low permeability. (2) If the container and the perforated plate for the permeability test are made of acrylic and the flange is made of non-metallic material, the impact on the X-ray CT measurement will be limited, and the saturation state inside the test specimen can be observed non-destructively. (3) If the perforated plate for the permeability test is made of acrylic, it will have considerable strength and will not break even if the area is increased, making it possible to reuse it. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a cross-sectional view schematically showing a water permeability test device according to the present invention. [Figure 2] (a) is a plan view showing a schematic diagram of a perforated plate for a permeability test, and (b) is a cross-sectional view showing a schematic diagram of a perforated plate for a permeability test. [Figure 3] (a) A plan view showing a schematic diagram of a perforated plate for permeability testing in which two annular lower surfaces are formed concentrically, and (b) a cross-sectional view showing a schematic diagram of a perforated plate for permeability testing in which two annular lower surfaces are formed concentrically. [Figure 4] FIG. 1 is a plan view showing a schematic diagram of a perforated plate for a water permeability test on which radially shaped lower surfaces are formed. [Figure 5] FIG. 2A is a plan view schematically showing a flange, and FIG. 2B is a cross-sectional view schematically showing the flange. [Figure 6] (a) is a cross-sectional view showing a top-side perforated plate arranged with its surface facing upward and a top-side flange arranged with its surface facing downward, and (b) is a cross-sectional view showing a bottom-side perforated plate arranged with its surface facing downward and a bottom-side flange arranged with its surface facing upward. [Figure 7] A cross-sectional view showing a schematic diagram of a perforated plate and flange for a permeability test stacked on top of each other with their surfaces facing each other. [Figure 8] 1 is a flow chart showing the main steps of the water permeability test method of the present invention. [Figure 9] (a) is a plan view of the flange surface, and (b) is a plan view of a conventional perforated plate. [Figure 10] (a) is a cross-sectional view showing the situation where water is supplied to overlapping flanges and perforated plates, and (b) is a cross-sectional view showing the situation where water is supplied using a perforated plate with additional water passage holes. DETAILED DESCRIPTION OF THE INVENTION

[0022] An example of an embodiment of the perforated plate for permeability testing, the permeability testing device, and the permeability testing method of the present invention will be described with reference to the drawings.

[0023] 1. Permeability test equipment First, the permeability test apparatus of the present invention will be described in detail with reference to the drawings. The permeability test apparatus of the present invention can utilize the permeability test perforated plate of the present invention. Therefore, while explaining the permeability test apparatus of the present invention, the permeability test apparatus of the present invention will also be described in detail. Furthermore, the permeability test method of the present invention is a method for conducting a permeability test using the permeability test apparatus of the present invention. Therefore, the permeability test apparatus of the present invention will be described first, and then the permeability test method of the present invention will be described.

[0024] 1 is a cross-sectional view showing a schematic diagram of a permeability test apparatus 100 of the present invention. As shown in this figure, the permeability test apparatus 100 of the present invention can be configured to include a perforated plate for permeability tests 200 of the present invention, a flange 300, a container 400, and a connecting member 500. The flange 300, perforated plate for permeability tests 200, container 400, perforated plate for permeability tests 200, and flange 300 are stacked in this order from the bottom, and the upper and lower flanges 300 are fastened together with the connecting member 500, thereby enabling a permeability test to be carried out.

[0025] A permeability test is generally carried out as follows: First, a specimen TP such as bentonite or soil material is placed in the container 400, and water is poured in from below after it is placed in the state shown in Figure 1. The water that passes through the specimen TP is then discharged from above, and the permeability coefficient of the specimen TP can be determined by measuring the amount of water per unit time.

[0026] As shown in FIG. 1, the perforated plates 200 for the permeability test are arranged vertically so as to sandwich the container 400, and the flanges 300 are arranged vertically so as to sandwich the perforated plates 200 for the permeability test and the container 400. For convenience, the perforated plate 200 for the permeability test arranged on the upper surface side of the container 400 will be specifically referred to as the "top perforated plate 200U", and the perforated plate 200 for the permeability test arranged on the lower surface side of the container 400 will be specifically referred to as the "bottom perforated plate 200L". Similarly, the flange 300 arranged on the upper surface side of the top perforated plate 200U will be specifically referred to as the "top flange 300U", and the flange 300 arranged on the lower surface side of the bottom perforated plate 200L will be specifically referred to as the "bottom flange 300L".

[0027] Below, each of the main elements constituting the water permeability test apparatus 100 of the present invention will be explained in detail.

[0028] (Perforated plate for water permeability test) FIG. 2 is a schematic diagram of a perforated plate 200 for permeability testing according to the present invention, where (a) is a plan view from above and (b) is a cross-sectional view cut along a vertical plane. As shown in this figure, the perforated plate 200 for permeability testing is a thin, plate-like member that includes an outer bank portion 210, an inner surface portion 220, a bottom surface portion 230, and water passage holes 240. While this figure shows the perforated plate 200 for permeability testing as being circular in plan view, the perforated plate 200 for permeability testing is not limited to a circular shape and can have various shapes, such as a polygonal shape. Because the perforated plate 200 for permeability testing is plate-shaped, it has two surfaces, a front and a back. For convenience, the surface on which the outer bank portion 210 and the bottom surface 230 are formed will be referred to as the "front surface," and the opposite surface will be referred to as the "back surface" (FIG. 2(b)).

[0029] A ring-shaped outer bank portion 210 is formed on the outer periphery of the surface of the perforated plate for permeability testing 200, and an inner bank portion 220 is formed in the area surrounded by this outer bank portion 210. A bottom portion 230 is formed over the entire area of ​​the inner bank portion 220, or over a portion of the area. For example, in the perforated plate for permeability testing 200 shown in FIG. 2, the entire area of ​​the inner bank portion 220 is formed as the bottom portion 230. As can be seen in FIG. 2(b), this bottom portion 230 is formed at a position one step lower than the upper surface of the outer bank portion 210 when viewed in cross section. In other words, the upper surface of the outer bank portion 210 is formed so that it is higher than the bottom portion 230, and it is formed like a bank that surrounds the periphery of the bottom portion 230. As a result, a recess is formed in the perforated plate for permeability testing 200 when viewed in cross section.

[0030] The lower surface portion 230 is formed with a plurality of small holes (hereinafter referred to as "water passage holes 240") that penetrate through the plate thickness direction. As will be described later, the perforated plate for permeability testing 200 is positioned so that its surface faces the "filling and draining groove" formed in the flange 300. Any of the plurality of water passage holes 240 is formed in a position that does not face this fill and draining groove when the perforated plate for permeability testing 200 and the flange 300 are positioned opposite each other. Of course, some of the water passage holes 240 can be formed in a position that faces the fill and draining groove, or all of the water passage holes 240 can be formed in a position that does not face the fill and draining groove. In other words, at least some (one or more) of the plurality of water passage holes 240 are formed in a position that does not face the fill and draining groove.

[0031] As mentioned above, in recent years, there has been a demand for non-destructive observation of the saturation state inside the test specimen TP, and opportunities to perform measurements using X-ray CT before and after a permeability test are increasing. Therefore, even when a permeability test is performed using the permeability test device 100 of the present invention, it is conceivable to perform measurements using X-ray CT. Therefore, it is desirable that the permeability test perforated plate 200 of the present invention be made of a material that has limited influence on the X-ray CT. For example, it is preferable to use a permeability test perforated plate 200 made of a non-metal or resin, especially an acrylic or polyvinyl chloride (PVC) perforated plate 200.

[0032] In the example of FIG. 2, the entire area of ​​the inner surface portion 220 is formed as the bottom surface portion 230. However, as described above, the bottom surface portion 230 can also be formed only in a portion of the inner surface portion 220. For example, in FIG. 3, two annular bottom surface portions 230 are formed concentrically, and because they are band-shaped, the bottom surface portion 230 is formed as a groove. Of course, one annular bottom surface portion 230 can be formed, or three or more annular bottom surface portions 230 can be formed. In this case, as shown in FIG. 3(b), a portion of the inner surface portion 220 that is not used as the bottom surface portion 230 remains, and the upper surface of this inner surface portion 220 can be formed at approximately the same height (including the same height) as the upper surface of the outer bank portion 210. In other words, the bottom surface portion 230 can be formed by cutting a portion of the surface of the thick plate-shaped material in the outer bank portion 210. However, the bottom surface 230 is formed so that when the perforated plate for permeability test 200 and the flange 300 are arranged opposite each other, part or all of the inlet and outlet grooves of the flange 300 are included within the bottom surface 230. Note that even when the bottom surface 230 is formed in a partial range of the inner surface 220 as shown in Figure 3, the water passage hole 240 is still formed in the bottom surface 230.

[0033] When forming the low surface portion 230 in a partial range of the inner surface portion 220, the low surface portion 230 can be formed in any shape other than the annular low surface portion 230 shown in Fig. 3. For example, the surface of the perforated plate for permeability test 200 shown in Fig. 4 has low surface portions 230 formed radially from a center point, and similar to Fig. 2, the low surface portions 230 are formed as grooves because they are band-shaped. Of course, it is also possible to form a combination of the annular low surface portion 230 shown in Fig. 3 and the radial low surface portion 230 shown in Fig. 4.

[0034] (flange) FIG. 5 is a schematic diagram of a flange 300, where (a) is a plan view from above and (b) is a vertical cross-sectional view. As shown in this figure, the flange 300 is a plate-shaped member that includes inlet and outlet holes 310 and inlet and outlet grooves 320, and may also include a sealant 330 and bolt holes 340. While this figure shows the flange 300 as being circular in plan view, the flange 300 is not limited to a circular shape and may have various shapes, such as a polygonal shape. Because the flange 300 is plate-shaped, it has two surfaces, a front and a back. For convenience, the surface on which the inlet and outlet grooves 320 are formed will be referred to as the "front surface" and the opposite surface as the "back surface" (FIG. 5(b)).

[0035] As shown in FIG. 5, a small hole (hereinafter referred to as "filling and draining hole 310") is formed in the center of flange 300 through the plate thickness, and a band-shaped groove-shaped filling and draining groove 320 is formed on the surface of flange 300. However, as shown in FIG. 5(b), filling and draining hole 310 and filling and draining groove 320 are formed so as to be connected. This filling and draining groove 320 can be formed in any shape. For example, the flange 300 shown in FIG. 5 has four consecutive filling and draining grooves 320 extending radially from filling and draining hole 310 and two annular filling and draining grooves 320 arranged concentrically. A sealing material 330 (so-called packing) can be arranged around the filling and draining grooves 320 on the surface of flange 300, and multiple bolt holes 340 (six in the figure) can be formed on the outer periphery of flange 300. Note that, for the same reasons as for perforated plate 200 for permeability testing of the present invention, it is desirable to construct flange 300 from a material that has limited effect on X-ray CT. For example, it is preferable to use a flange 300 made of a non-metal or resin, particularly an acrylic or polyvinyl chloride flange 300.

[0036] (Containment Unit) The container 400 is a cylindrical member with openings at the top and bottom, and is capable of containing the test specimen TP. For the same reasons as for the perforated plate for permeability testing 200 of the present invention, it is desirable that the container 400 be made of a material that has limited influence on X-ray CT. For example, it is preferable to use a container 400 made of a non-metal or resin, particularly an acrylic or polyvinyl chloride container 400.

[0037] (Connecting material) As shown in FIG. 1 , the connecting member 500 clamps and fastens the bottom flange 300L and the top flange 300U together in the following order from the bottom: bottom flange 300L, bottom perforated plate 200L, container 400, top perforated plate 200U, and top flange 300U. For example, the connecting member 500 shown in FIG. 1 is configured with bolts 510 and nuts 520, and the bolts 510 are inserted through bolt holes 340 in the top flange 300U and bottom flange 300L and fastened with the nuts 520. Of course, the connecting member 500 can also be configured using a clamp-type jig or the like, as long as it can clamp and fasten the bottom flange 300L and the top flange 300U. For the same reasons as for the perforated plate 200 for permeability testing of the present invention, it is desirable to configure the connecting member 500 using a material that has limited effect on X-ray CT. For example, it is preferable to use a non-metallic or resin connecting material 500, particularly an acrylic or polyvinyl chloride connecting material 500.

[0038] When the perforated plate 200 for the water permeability test and the flange 300 are stacked, they are arranged so that their surfaces face each other. That is, as shown in Figure 6(a), the top perforated plate 200U is arranged so that its surface faces upward and the top flange 300U is arranged so that its surface faces downward, and as shown in Figure 6(b), the bottom perforated plate 200L is arranged so that its surface faces downward and the bottom flange 300L is arranged so that its surface faces upward. Then, the lower opening of the test piece TP is closed by the back surface (i.e., the upper surface) of the bottom perforated plate 200L, and the upper opening of the test piece TP is closed by the back surface (i.e., the lower surface) of the top perforated plate 200U.

[0039] 7 is a cross-sectional view showing a schematic diagram of the perforated plate for permeability test 200 and the flange 300, which are arranged so that their surfaces face each other and are stacked one on top of the other. As described above, the lower surface portion 230 is formed at a position one step lower than the upper surface of the outer bank portion 210, so that a recess is formed in the perforated plate for permeability test 200 when viewed in cross section. When the perforated plate for permeability test 200 and the flange 300 are stacked and the upper surface of the outer bank portion 210 abuts against the surface of the flange 300 (the lower surface in the figure), the upper part of the recess in the perforated plate for permeability test 200 is closed by the surface of the flange 300, and a closed space (hereinafter referred to as "void portion 250") is formed.

[0040] The void 250 is connected to the inlet and drainage holes 310 and the inlet and drainage grooves 320 of the flange 300, and also to the water passage holes 240 of the perforated plate for permeability test 200. In other words, the inlet and drainage grooves 320 (or the inlet and drainage holes 310) and the water passage holes 240 are not directly connected, but are indirectly connected via the void 250. In other words, water injected into the inlet and drainage holes 310 of the top flange 300U passes through the inlet and drainage holes 310 and the inlet and drainage grooves 320 and is supplied to the void 250, then passes through the multiple water passage holes 240 and permeates into the test piece TP of the container body 400. Furthermore, water that has permeated the test piece TP of the container 400 passes through the multiple water passage holes 240 and is supplied to the void 250, then passes through the inlet and outlet holes 310 and the inlet and outlet grooves 320, and is discharged from the inlet and outlet holes 310 of the bottom flange 300L. Due to the effect of forming the void 250 in this way, when the surfaces of the perforated plate for permeability test 200 and the flange 300 are arranged opposite each other, even if all of the water passage holes 240 are formed in positions that do not face the inlet and outlet grooves 320, water injected into the inlet and outlet holes 310 of the top flange 300U permeates the test piece TP of the container 400 and is discharged from the inlet and outlet holes 310 of the bottom flange 300L. In other words, when the surfaces of the perforated plate 200 for permeability testing and the flange 300 are arranged opposite each other, the water passage holes 240 can be added at positions that do not face the inlet / outlet grooves 320, meaning that the water passage holes 240 can be added at desired positions regardless of the arrangement of the inlet / outlet grooves 320.

[0041] (Variation) The permeability test apparatus 100 of the present invention may be equipped with a conventional perforated plate instead of the perforated plate for permeability testing 200 of the present invention. Here, the conventional perforated plate is a plate-shaped plate having a plurality of water passage holes 240, and does not have an outer bank portion 210, an inner surface portion 220, or a bottom surface portion 230 formed thereon, as in the perforated plate for permeability testing 200. However, assuming that X-ray CT measurements will be performed when conducting a permeability test using the permeability test apparatus 100 of the present invention, it is desirable that the perforated plate, flange 300, container 400, and connecting member 500 be made of materials that have limited influence on the X-ray CT. For example, the perforated plate, flange 300, container 400, and connecting member 500 made of non-metallic or resin materials may be used, and in particular, the perforated plate, flange 300, container 400, and connecting member 500 made of acrylic or polyvinyl chloride may be used. In this case, the water passage hole 240 should be provided in a position opposite the inlet / outlet groove 320 when the surfaces of the perforated plate for permeability testing 200 and the flange 300 are arranged opposite each other, as in the conventional case.

[0042] 2.Permeability test method Next, the permeability test method of the present invention will be described with reference to Figure 8. The permeability test method of the present invention is a method for conducting a permeability test using the permeability test apparatus 100 described up to this point. Therefore, we will avoid any explanation that overlaps with the content explained for the permeability test apparatus 100, and will mainly explain the content that is unique to the permeability test method of the present invention. In other words, content not described here is the same as that explained in "1. Permeability test apparatus."

[0043] 8 is a flow diagram showing the main steps of the permeability test method of the present invention. When conducting a permeability test using the permeability test apparatus 100, first, the bottom flange 300L is placed on a floor or other surface with its front surface facing up (Step 201 in FIG. 8), and the bottom perforated plate 200L is placed on the front surface (i.e., the top surface) of the bottom flange 300L with its front surface facing down (Step 202 in FIG. 8). Next, the container 400 is placed on the back surface (i.e., the top surface) of the bottom perforated plate 200L (Step 203 in FIG. 8), and then a test specimen TP such as bentonite or soil material is placed inside the container 400 (Step 204 in FIG. 8).

[0044] When the specimen TP is contained in the container 400, the top perforated plate 200U is placed on the top surface of the container 400 so that its surface faces upward (Step 205 in FIG. 8), and the top flange 300U is placed on the surface (i.e., the upper surface) of the top perforated plate 200U so that its surface faces downward (Step 206 in FIG. 8). Then, with the top flange 300U and the bottom flange 300L sandwiching the container 400, the top perforated plate 200U, and the bottom perforated plate 200L, the top flange 300U and the bottom flange 300L are fastened together by the connecting material 500 (Step 207 in FIG. 8).

[0045] Once these preparations are complete, the permeability test begins (Step 208 in FIG. 8). Specifically, the permeability coefficient of the specimen TP is determined by continuously injecting water through the inlet and drainage holes 310 in the bottom flange 300L, permeating the specimen TP in the container 400, and measuring the amount of water discharged per hour through the inlet and drainage holes 310 in the top flange 300U. When using low-permeability materials, it is desirable to pass water from the inlet and drainage holes 310 in the bottom flange 300L to the inlet and drainage holes 310 in the top flange 300U in order to expel air bubbles inside the specimen TP or minimize the effect of gravity on the permeability coefficient. However, when using high-permeability materials, it is also possible to pass water from the inlet and drainage holes 310 in the top flange 300U to the inlet and drainage holes 310 in the bottom flange 300L. [Industrial Applicability]

[0046] The perforated plate for permeability testing, the permeability testing device, and the permeability testing method can be used to measure the permeability coefficient of various materials, including soil materials, and are particularly effective when measuring the permeability coefficient of low-permeability materials such as bentonite. For example, after confirming that the bentonite has low permeability (high water-blocking properties), the bentonite can be used as a cover for shallow underground pit disposal or buried waste. In this sense, the present invention provides a suitable solution to the urgent issue of radioactive waste disposal, and can be expected to not only be useful in industry but also to make a significant contribution to society. [Explanation of symbols]

[0047] 100 Permeability test device of the present invention 200 Perforated plate for permeability test of the present invention 200U (Top perforated plate for permeability test) 200L (of the perforated plates for permeability testing) bottom perforated plate 210 (Perforated plate for permeability test) outer bank 220 (Inner surface of perforated plate for permeability test) 230 (lower surface of perforated plate for permeability test) 240 (Perforated plate for permeability test) Water passage hole 250 (permeability test device) void 300 (Permeability test equipment) flange 300U (of the flanges) Top flange 300L (of the flanges) Bottom flange 310 (Flange) Inlet / Outlet Hole 320 (Flange) Inlet / Outlet 330 (Flange) sealing material 340 (Flange) Bolt Hole 400 (Permeability Testing Device) Housing 500 (Permeability test equipment) connecting material 510 (Connector) Bolt 520 (Connector) Nut FL flange HB perforated plate IH injection / discharge port pH water passage RS Oリング TP test subject WG drainage ditch

Claims

1. A perforated plate used in a permeability test, an outer bank portion formed on the outer periphery of the surface; a low surface portion formed on all or part of the inner surface portion surrounded by the outer bank portion of the surface; a plurality of water passage holes formed in the lower surface portion, When viewed in cross section, the low surface portion is formed at a position lower than the outer bank portion, A perforated plate for water permeability testing characterized by:

2. The lower surface portion is formed in one or more annular groove shapes.

2. The perforated plate for water permeability testing according to claim 1.

3. An apparatus used in a permeability test, a cylindrical container for accommodating the specimen; A plate-shaped perforated plate for permeability testing; a flange having a pouring / draining groove formed on its surface and having pouring / draining holes communicating with the pouring / draining groove; a connecting material; The perforated plate for the permeability test has an outer bank portion formed on the outer periphery of the surface, a lower surface portion formed on all or part of the inner surface portion surrounded by the outer bank portion of the surface, and a plurality of water passage holes formed in the lower surface portion, and when viewed in cross section, the lower surface portion is formed at a position lower than the outer bank portion, The perforated plate for the water permeability test is placed on the upper surface of the container containing the test specimen so that the surface is facing upward, The perforated plate for the water permeability test is placed on the underside of the container containing the test specimen so that the surface faces downward, The flange is placed on the upper surface of the perforated plate for water permeability testing, which is placed on the upper surface of the container, so that the surface faces downward; The flange is placed on the lower surface of the perforated plate for water permeability testing, which is placed on the lower surface of the container, so that the surface is facing upward; The upper and lower flanges clamp the container and the upper and lower perforated plates for water permeability testing, and the connecting material fastens the upper and lower flanges together. The one or more water passage holes are arranged in a position that does not face the inlet / outlet groove when the perforated plate for water permeability test and the flange are arranged opposite each other. A water permeability test device characterized by:

4. The container and the perforated plate for water permeability testing are made of acrylic, The flange is made of polyvinyl chloride.

4. The water permeability test device according to claim 3.

5. An apparatus used in a permeability test, a cylindrical container for accommodating the specimen; A plate-shaped perforated plate having a plurality of water passage holes; a flange having a pouring / draining groove formed on its surface and having pouring / draining holes communicating with the pouring / draining groove; a connecting material; The perforated plate is placed on the upper surface of the container that contains the specimen, The perforated plate is placed on the lower surface of the container that contains the specimen, The flange is disposed on the upper surface of the perforated plate disposed on the upper surface of the container so that the surface faces downward; The flange is disposed on the lower surface of the perforated plate disposed on the lower surface of the container so that the surface faces upward; The upper and lower flanges are clamped between the housing and the upper and lower perforated plates by the connecting material, The container and the perforated plate are made of acrylic, and the flange is made of polyvinyl chloride. A water permeability test device characterized by:

6. A method for measuring the permeability coefficient of a specimen using a permeability test device, comprising: The water permeability test device comprises a cylindrical container for accommodating the test specimen, a plate-shaped perforated plate for water permeability testing having a plurality of water holes, a flange having a water inlet / outlet groove formed on the surface and having water inlet / outlet holes communicating with the water inlet / outlet groove, and a connecting material; A bottom side arrangement step of arranging the flange so that the surface is facing up and arranging the perforated plate for water permeability testing on the upper surface of the flange so that the surface is facing down; A specimen accommodation step of arranging the container on the upper surface of the perforated plate for water permeability testing arranged on the upper surface of the flange and accommodating the specimen in the container; A top-side arrangement step of arranging the perforated plate for water permeability testing on the upper surface of the container in which the test specimen is accommodated so that the surface is facing up, and arranging the flange on the upper surface of the perforated plate for water permeability testing so that the surface is facing down; A flange fastening process for fastening the upper and lower flanges with the connecting material while the upper and lower flanges sandwich the container and the upper and lower perforated plates for water permeability testing, Water is poured into the inlet and outlet groove of the lower flange, passes through the water passage holes of the lower perforated plate for the perforated permeability test, the test piece contained in the container, and the water passage holes of the upper perforated plate for the perforated permeability test, and is then drained from the inlet and outlet groove of the upper flange. The permeability coefficient of the test piece can be determined based on the results. A water permeability test method characterized by the above.

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