JP2015175623A - Percolation test method and percolation test device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the adhesion of a member covering a sample side surface to the sample side surface and prevent density variation of a sample.SOLUTION: A side surface of a specimen 20 is covered with a non-permeable and flexible coating member 10 while the vertical (axial direction) expansion and deformation of the specimen 20 is restricted. Water is made to pass through (permeate) the specimen 20, in the state in which the horizontal and outward displacement is restricted and cell pressure is applied to the coating member 10 by disposing a binding mold 7 on the outer periphery of the coating member 10.

Description

  The present invention relates to a permeability test method and a permeability test apparatus. More specifically, the present invention relates to a test method and test apparatus suitable for use in, for example, a triaxial permeability test of a high swelling pressure sample.

  As a conventional permeability test for obtaining a permeability coefficient in a laminar flow state of a soil in a saturated state, there are those specified in Japanese Industrial Standards JIS A 1218 and ASTM International DAST ASTM D5084.

  As shown in FIG. 3, the water permeability test method using a rigid container defined in JIS A 1218 includes a high-swelling pressure sample 101, and a lower porous plate 102 </ b> A and an upper porous plate 102 </ b> B sandwiching the sample 101. And water is injected from the water injection pipe 104, and the water passes through the lower porous plate 102A, the sample 101, and the upper porous plate 102B and is discharged from the drain pipe 105 (non-patented). Reference 1).

  Further, as shown in FIG. 4, the water permeability test method using the triaxial test apparatus defined in ASTM D5084 is performed by sandwiching the high swelling pressure sample 111 between the lower porous plate 112A and the upper porous plate 112B and then the upper side. And the lower peripheral columns 116A and 116B, and the side circumferential surface of the sample 111 is surrounded by a rubber film 117. The entire specimen thus configured is immersed in the sealed water tank 113, and the upper and lower The restraint columns 116A and 116B restrain the vertical movement of the lower and upper perforated plates 112A and 112B and inject gas from the gas pipe 118 to apply gas pressure into the water tank 113, thereby allowing the sample 111 to pass through the water. Water is injected from the water injection pipe 114 while applying a cell pressure to the rubber film 117 surrounding the side peripheral surface, and the water passes through the lower porous plate 112A, the sample 111, and the upper porous plate 112B. This is performed by discharging from the drainage pipe 115 (Non-patent Document 2). In addition, the code | symbol 119 in a figure is the rubber band for water stop.

Japanese Industrial Standards JIS A 1218 Soil Permeability Test Method ASTM International ASTM D5084 Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter

  However, in the water permeability test method using a rigid container specified in JIS A 1218, since the large swelling pressure when the high swelling pressure sample 101 swells acts on the rigid container 103, the high pressure gas safety method (Showa 26) Since it is not subject to regulation based on Law No. 204 of June 7), it does not have to satisfy the requirements of the law, and the deformation at the time of swelling of the high swelling pressure sample 101 is restrained by the rigid container 103 Therefore, in the case of a sampling sample, when the adhesion between the side surface of the sample and the inner side surface of the container is not sufficient, the locality that passes through the boundary surface is obtained. There is a problem that the hydraulic conductivity may be overestimated due to the occurrence of a general flow (water path).

  Further, in the water permeability test method using the triaxial test apparatus stipulated in ASTM D5084, the rubber film 117 has high adhesion to the side surface of the sample 111, and therefore a local flow (water channel) passing through the boundary surface is generated. While it has the feature that it is difficult, it is subject to regulation based on the High Pressure Gas Safety Law, so it is necessary to satisfy the requirements of the law, and the swelling pressure is unknown, so it is considered to be larger than the swelling pressure Since the cell pressure has to be set, there is a problem that the water permeability coefficient is underestimated because the sample 111 contracts and density increases.

  Therefore, in the present invention, since the adhesiveness between the sample side surface and the sample side surface is high, local flow through the boundary surface is difficult to occur, and therefore the change in the water permeability coefficient of the sample can be prevented. Further, there is provided a water permeability test method and a water permeability test apparatus that can prevent a change in the water permeability coefficient of the sample because the density change of the sample does not occur and is not subject to regulation based on the High Pressure Gas Safety Law. The purpose is to do.

  In order to achieve this object, the water permeation test method according to claim 1 surrounds a side surface of the test specimen along the one direction with a non-water-permeable and flexible covering member while restricting expansion deformation in one direction of the test specimen. In addition, a restraining member is disposed on the outer periphery of the covering member to restrict outward displacement in a direction perpendicular to the one direction and to allow water to permeate (infiltrate) the specimen with cell pressure applied to the covering member. I am doing so.

  In addition, the permeability test apparatus according to claim 4 includes a water tank, an upper restraint column projecting downward from the lower surface of the upper lid of the water tank, a lower restraint column projecting upward from the upper surface of the bottom plate of the water tank, and a lower restraint column. Surrounds the side surface of the specimen with the upper water-permeable member disposed on the upper end of the specimen and the upper water-permeable member disposed on the upper end of the specimen and the upper surface of the lower restraining column and disposed on the lower end of the specimen. It has a non-water-permeable and flexible covering member and a constraining mold disposed in contact with the outer periphery of the covering member, and the test specimen is subjected to cell pressure applied to the covering member by water stored in the water tank. The water is made to pass (permeate).

  Therefore, according to the water permeability test method and the water permeability test apparatus, since the cell pressure is applied through the constraining mold and the covering member is pressed against the specimen, the covering member is brought into close contact with the side face of the specimen, thereby locally passing the boundary surface. It is difficult to generate a general flow.

  According to the water permeability test method and the water permeability test apparatus, the deformation at the time of swelling of the specimen is controlled by the restraint mold, so that it is considered to be larger than the swelling pressure of the specimen to suppress the deformation at the time of swelling. There is no need to apply cell pressure to the specimen, i.e., the specimen does not shrink, so the density of the sample does not increase, and therefore the permeability coefficient of the specimen does not change.

  According to these water permeability test methods and devices, the deformation of the specimen is limited by the constraining mold, that is, the specimen does not expand, so the density of the specimen does not decrease, and therefore the specimen No change in hydraulic conductivity occurs.

  According to the water permeability test method and the water permeability test apparatus, since the restraint ring is responsible for the large swelling pressure when the specimen swells, it is not necessary to increase the cell pressure. Therefore, it is not necessary to satisfy the requirements stipulated in the law as the performance and specifications of the apparatus.

  In the water permeability test method and the water permeability test apparatus of the present invention, the covering member may be a rubber sleeve. In this case, the covering member is suitable as a film-like member having impermeableness and flexibility.

  Further, the water permeability test method of the present invention may be configured by a plurality of layers of a water permeable layer on the side where the restraining member abuts on the covering member and a layer on the outer peripheral side. The constraining mold may be composed of a plurality of layers of a water-permeable layer on the side in contact with the covering member and a layer on the outer peripheral side. In these cases, the configuration of the restraining member and the restraining mold becomes flexible.

  According to the water permeability test method and the water permeability test apparatus of the present invention, the covering member can be brought into close contact with the side surface of the specimen, thereby making it difficult to generate a local flow through the boundary surface. Can be measured accurately, and the reliability of the water permeability test can be improved.

  According to the water permeability test method and the water permeability test apparatus of the present invention, the specimen can be prevented from shrinking during the water permeability test, and the density of the sample can be prevented from increasing. It is possible to accurately measure the permeability coefficient without causing a change in the coefficient, and it is possible to improve the reliability of the permeability test.

  According to the water permeation test method and the water permeation test apparatus of the present invention, the specimen can be prevented from expanding during the water permeation test, and the sample density can be prevented from decreasing. It is possible to accurately measure the permeability coefficient without causing a change in the coefficient, and it is possible to improve the reliability of the permeability test.

  According to the permeability test method and the permeability test apparatus of the present invention, it is not necessary to satisfy the requirements stipulated in the High Pressure Gas Safety Law as the performance and specifications of the apparatus. Therefore, it is necessary to make the structure of the apparatus unnecessarily heavy. In addition, it is possible to improve versatility as a water permeability test in that there is no legal restriction.

  In the water permeability test method and the water permeability test apparatus according to the present invention, the covering member may be a rubber sleeve. In this case, the covering member is a membrane-like member having water permeability and flexibility. It becomes possible to make it appropriate.

  Further, the water permeability test method and the water permeability test apparatus according to the present invention may be configured by a plurality of layers of a water permeable layer on the side where the restraining member or the restraining mold abuts the covering member and a layer on the outer peripheral side. In this case, it is possible to diversify the structures of the restraining member and the restraining mold.

It is a figure which shows an example of embodiment of the water-permeable test apparatus of this invention, and is II-II arrow line view of FIG. It is a figure which shows the water-permeable test apparatus of embodiment, and is the II arrow directional view of FIG. It is a longitudinal cross-sectional view which shows the conventional water-permeable test apparatus. It is a longitudinal cross-sectional view which shows the conventional triaxial permeability test apparatus.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 and 2 show an example of an embodiment of a water permeability test method and a water permeability test apparatus of the present invention. In FIG. 1, the X axis is the horizontal direction, and the Z axis is the vertical direction. In the following description, the Z-axis direction is the axial direction of the specimen 20 and the vertical direction for the water permeability test apparatus and its components.

  In the water permeability test method, the side surface of the specimen 20 is surrounded by a non-water-permeable and flexible covering member 10 and restricted to the outer periphery of the covering member 10 while restricting expansion and deformation of the specimen 20 in the vertical direction (axial direction). The mold 7 is disposed to restrict the outward displacement in the horizontal direction and allow water to permeate (permeate) the specimen 20 with the cell pressure applied to the covering member 10.

  Then, the water permeability test apparatus executes the above water permeability test method. The water tank 1, the upper restraint column 5A protruding downward from the lower surface of the upper lid 1a of the water tank 1, and the lower surface protruding upward from the upper surface of the bottom plate of the water tank 1. The side restraint column 5B is in contact with the lower end surface of the upper side restraint column 5A, and is in contact with the upper end surface of the upper water-permeable member 6A and the lower side restraint column 5B disposed at the upper end of the specimen 20, and at the lower end of the specimen 20 The lower water-permeable member 6 </ b> B to be disposed, the non-water-permeable and flexible coating member 10 surrounding the side surface of the specimen 20, and the restraint mold 7 disposed in contact with the outer periphery of the coating member 10. In addition, water is passed through (infiltrated) the specimen 20 with the cell pressure applied to the covering member 10 by the water 13 stored in the water tank 1.

  The sample used as the specimen 20 of the present invention is not limited to a specific sample, and examples thereof include materials having at least water permeability, such as various ground materials. It should be noted that the Japanese Industrial Standard JIS A 1218 “Soil Permeability Test Method” and ASTM D5084 “Standard Test Methods for Measurement of Hydraulic Porous Materials Usable a Paliblemeter” by ASTM International A possible sample can be an object to which the present invention is applied (that is, the specimen 20). Specifically, for example, bentonite or bentonite mixed soil can be an application target of the present invention. In addition, the specimen 20 may be a sample made by compacting a sample collected at the site, or a sample sample as it is sampled at the site.

  The size of the specimen 20 is not limited to a specific size, and can be appropriately adjusted according to, for example, the size of a sample that can be collected (however, the specimen 20 can be adjusted in the axial direction in principle). Have a constant cross-sectional area). According to Japanese Industrial Standards JIS A 1218 “Soil Permeability Test Method”, a water permeable cylinder accommodating a specimen is assumed to be a cylinder having a sufficiently large inner diameter and length compared to the maximum particle diameter of the sample. The length is assumed to be 12 cm. Also in the present invention, the concept of the size of the specimen (columnar shape) as the size of the water-permeable cylinder defined in Japanese Industrial Standard can be applied.

  The water tank 1 is used for applying a cell pressure to the specimen 20 while keeping the specimen 20 in a water-immersed state, and includes a main body 1b having an upper lid 1a, a bottom plate, and a peripheral wall. Although not shown, the water tank 1 is appropriately provided with a rubber packing (O-ring) at a location necessary for ensuring watertightness and airtightness.

  The upper lid 1a of the water tank 1 is detachable with respect to the main body 1b. In addition, a rubber packing (O-ring) is provided at a contact portion with the upper end surface of the peripheral wall of the main body 1b, and the rubber packing (O-ring) is attached to the rubber packing (O-ring). It is mounted in a state in which airtightness is ensured with the main body 1b by being pressed.

  In order to securely maintain the mounting state in which the airtightness of the upper lid 1a is ensured, a fixing structure (for example, a screw structure) is provided at both ends, and the upper lid 1a is bridged between the upper lid 1a and the bottom plate and is attached to the peripheral wall. One or a plurality of metal bars or the like may be provided as necessary to securely fix them.

  On the lower surface of the upper lid 1a of the water tank 1, a columnar upper restraint column 5A (also called a cap) that protrudes downward into the main body 1b is provided, and on the upper surface of the bottom plate of the main body 1b, the upper restraint column 5A and A columnar lower restraint column 5B (also referred to as a pedestal) that protrudes upward toward the inside of the main body 1b is provided at a position facing directly. The upper restraint column 5A and the lower restraint column 5B are provided in a fixed position in the water tank 1.

  The upper restraint column 5A and the lower restraint column 5B limit the upward displacement of the upper permeable member 6A and limit the downward displacement of the lower permeable member 6B, thereby restricting deformation due to swelling of the specimen 20. To do. The lower end surface of the upper restraint column 5A and the upper end surface of the upper water-permeable member 6A are brought into contact with each other, and the upper end surface of the lower restraint column 5B and the lower end surface of the lower water-permeable member 6B are brought into contact with each other.

  In addition, as long as the upper side restraint column 5A and the lower side restraint column 5B are position-fixed in the water tank 1, a specific structure is not limited to what is shown in FIG. 1, For example, the metal rod for position fixing It may be fixed to the upper lid 1a or the bottom plate via the like.

  The sizes of the lower end surface of the upper restraint column 5A and the upper end surface of the lower restraint column 5B are adjusted to be the same as the sizes of the upper end surface and the lower end surface of the specimen 20. The dimensions between the lower end surface of the upper restraint column 5A and the upper end surface of the lower restraint column 5B are the length of the specimen 20 (ie, the dimension in the axial direction), the thickness of the upper water-permeable member 6A, and the lower side. It adjusts so that it may become the same with the sum total of the thickness of water-permeable member 6B.

  The water tank 1 has a water passage pipe 2, a drain pipe 3, and a pressurization pipe 4.

  The water flow pipe 2 is for supplying water to which a predetermined water pressure is applied to the specimen 20. In addition, the water pressure given to the water supplied from the piping 2 for water flow is not limited to a specific value, for example, the hydrodynamic gradient in the field where the sample to be tested (the specimen 20) is collected, The value is appropriately set in consideration of the purpose of the water permeability test. Specifically, for example, it may be set in a range of about 0.001 to 1.0 [MPa].

  The water passage pipe 2 enters the bottom plate from the side of the main body 1b of the water tank 1, penetrates the bottom plate and the lower restraint column 5B, and has an open end on the upper end surface of the lower restraint column 5B.

  Further, a water pressure applying means (not shown) configured by, for example, a pressure tank filled with water of a predetermined pressure, a syringe pump, or the like is connected to the external end of the water tank 1 of the water passage pipe 2. In addition, a valve is appropriately provided in the water passage pipe 2 as necessary.

  Water with a constant water pressure is supplied to the lower end surface of the specimen 20 through the lower water-permeable member 6B by the water pressure applying means connected to the water passage pipe 2. That is, the lower end surface of the specimen 20 becomes the water injection end surface.

  The drainage pipe 3 is for discharging the water supplied from the water passage pipe 2 and passing through the lower water-permeable member 6B, the specimen 20 and the upper water-permeable member 6A (in other words, permeating). In addition, the upper end surface of the specimen 20 becomes a drainage end surface.

  The drainage pipe 3 passes through the upper lid 1a of the water tank 1 and the upper restraint column 5A, and has an open end on the lower end surface of the upper restraint column 5A.

  Further, a water amount measuring instrument (not shown) such as a graduated cylinder for measuring the amount of discharged water is provided at the outer end of the water tank 1 of the drain pipe 3.

  The pressurizing pipe 4 is for injecting a gas to which a predetermined pressure is applied into the main body 1 b of the water tank 1. Then, the cell pressure is applied to the covering member 10 and the specimen 20 through the water 13 stored in the main body 1 b of the water tank 1 by the pressurized gas injected from the pressurizing pipe 4.

  The cell pressure is used to prevent a local flow (water channel) passing through the boundary surface by causing the outer peripheral surface of the specimen 20 and the inner peripheral surface of the covering member 10 to be in close contact with each other. As long as the covering member 10 is in close contact with the side surface of the specimen 20, the value is not limited to a specific value. For example, the covering member 10 is appropriately set to an appropriate value according to the water pressure of water supplied from the water flow pipe 2. Adjusted. Specifically, for example, it may be set in the range of about 0.1 to 0.4 [MPa] as an example.

  An upper water-permeable member 6A is disposed between the lower end surface of the upper restraint column 5A and the upper end surface of the specimen 20 (in other words, in contact with the lower end surface of the upper restraint column 5A). A lower water permeable member 6B is disposed between the lower end surface of the lower restraint column 5B and the upper end surface of the lower restraint column 5B (in other words, in contact with the upper end surface of the lower restraint column 5B). In addition, between the upper end surface of the specimen 20 and the upper water-permeable member 6A and between the lower surface of the specimen 20 and the lower water-permeable member 6B, a filter paper or particles of the specimen 20 are used to prevent the outflow of a trickle due to water permeability. A filter having a hole diameter corresponding to the diameter is appropriately disposed.

  The diameters of the upper water permeable member 6A and the lower water permeable member 6B in a plan view (circular shape) are adjusted to be the same as the diameters of the upper and lower end surfaces of the specimen 20.

  That is, the specimen 20 is sandwiched between the lower permeable member 6B on the lower end (ie, water injection end face) side and the upper permeable member 6A on the upper end (ie drainage end face) side.

  As the upper water permeable member 6A and the lower water permeable member 6B, a member having water permeability to such an extent that it does not affect the water permeability of the specimen 20 by having a large number of small holes and voids and having corrosion resistance is used. It is done.

  Examples of the upper water permeable member 6A and the lower water permeable member 6B include those that can be used as perforated plates in Japanese Industrial Standard JIS A 1218 “Soil Permeability Test Method”, and Geotechnical Society Standard JGS 0522 “Soil Consolidation Non- What can be used as a perforated plate in the “drainage (CU) triaxial compression test method” (hereinafter simply referred to as “geological engineering society standards”) may be used.

  The covering member 10 covers the entire side surface of the specimen 20 installed between the upper restraint column 5A and the lower restraint column 5B, restricts water permeation and drainage, and transmits the cell pressure to the side surface of the specimen 20. Therefore, a member that exhibits these properties and behaviors, specifically, a film-like member having water permeability and flexibility is used. For example, what can be used as a rubber sleeve in the Geotechnical Society standards can be used as the covering member 10 of the present invention.

  The covering member 10 is passed over and attached to the upper restraint column 5A and the lower restraint column 5B. That is, the covering member 10 is wound around the side circumferential surface of the upper restraint column 5A at the upper end portion, wound around the side circumferential surface of the specimen 20 at the middle portion, and is disposed on the side circumferential surface of the lower restraint column 5B. Wrapped around.

  The covering member 10 is detachably attached in a state where watertightness is ensured between the covering member 10 and the upper restraint column 5A by being annularly tightened from the outside by the upper water stop member 11A in a position near the upper end, and a position near the lower end. In FIG. 5, the lower water stop member 11B is tightened in an annular shape from the outside so as to be detachably attached in a state in which water tightness is secured with respect to the lower restraint column 5B.

  The upper and lower water stop members 11A and 11B are limited to specific members as long as the covering member 10 can be attached to the upper restraint column 5A and the lower restraint column 5B in a state of ensuring watertightness. It is not something. Specifically, for example, a rubber band, an O-ring, or a wire can be used.

  In addition, an upper sample outflow prevention member 12A is attached to a position between the upper water stop member 11A and the lower end surface of the upper restraint column 5A in the vertical direction, and the lower water stop member 11B and the lower restraint column are attached. The lower sample outflow prevention member 12B is attached to a position between the upper end surface of 5B in the vertical direction.

  The upper / lower sample outflow prevention members 12A, 12B can prevent the outflow of the specimen 20 from between the upper / lower restraint columns 5A, 5B and the covering member 10 in close contact with each other and sealed. If there is, it is not limited to a specific member. Specifically, for example, a rubber band, an O-ring, or a wire can be used.

  Instead of the upper / lower sample outflow prevention members 12A, 12B, at least one of these is provided at the position where the upper / lower restraint columns 5A, 5B and the restraint mold 7 face each other. The covering member 10 may be crimped to prevent the specimen 20 from flowing out between the upper and lower restraining columns 5A and 5B and the covering member 10.

  Further, when the upper and lower sample outflow prevention members 12A and 12B can prevent the inflow of the water 13 in the main body 1b from between the upper and lower restraint columns 5A and 5B and the covering member 10. The upper and lower water stop members 11A and 11B may not be provided.

  The constraining mold 7 is for restricting deformation of the specimen 20 due to swelling by restricting the outward displacement of the covering member 10 in the horizontal direction, and is formed in a cylindrical shape. It is made to contact | abut to.

  The constraining mold 7 has sufficient water permeability (void, porosity) so that the cell pressure due to the water 13 (and gas 14) stored in the main body 1b of the water tank 1 does not become an obstacle to the transmission to the covering member 10. On the other hand, the inner peripheral surface, which is the contact surface with the covering member 10, has at least fineness that does not cause deformation such that fine unevenness occurs in the covering member 10 and the specimen 20 due to the swelling pressure of the specimen 20. .

  The constraining mold 7 is detachably attached to a mold fixing jig 9 provided to be fixed to the bottom plate of the main body 1 b of the water tank 1. In the present embodiment, four mold fixing jigs 9 are provided at equal intervals at a peripheral position separated from the lower restraint column 5B in plan view, and the covering member 10 is wound around the side peripheral surface of the lower restraint column 5B. The lower end portion of the constraining mold 7 is inserted between the mold fixing jig 9 and the lower end of the constraining mold 7 is supported by a protruding portion that protrudes from the mold fixing jig 9 toward the lower constraining column 5B. As a result, the restraint mold 7 is fixed in position with respect to the upper restraint column 5A and the lower restraint column 5B, the specimen 20 between the restraint columns 5A and 5B, the upper water permeable member 6A, and the lower water permeable member 6B. (The shaft rotation of the constraining mold 7 may not be limited).

  Then, the upper restraint column 5A, the lower restraint column 5B, the covering member 10 and the restraint mold 7 surround the specimen 20, the upper permeable member 6A, and the lower permeable member 6B, and fix the position of the specimen 20 in the water tank 1. In addition, a space for limiting deformation is formed.

  In the present embodiment, the constraining mold 7 is configured to be divided into two parts by a cut surface in the axial direction, and the mold constraining member is in a state of being combined and brought into contact with the outer peripheral surface of the covering member 10. 8 tightened.

  In this embodiment, the mold restraining member 8 is configured such that two belt-like members are connected to form a ring shape as a whole. Specifically, the two members having a semicircular arc shape in a plan view and a side band shape in a side view are rotated by a rotation shaft 8a penetrating through a connecting portion provided at one end of each in a positional relationship in which the member is annular as a whole. While being connected freely, each other end is provided with a protrusion radially outward. Then, the constraining mold 7 is inserted inside in a state of being rotated and spread by the rotating shaft 8a, and subsequently rotated and closed by the rotating shaft 8a to form two semicircular arcs. The protrusions at the other end of the member are brought into contact with each other and are aligned, and the cap 8b is fitted to these two protrusions to maintain a ring-like state as a whole. As a result, the two-part restraining mold 7 is tightened in a combined state.

  In the present embodiment, three mold restraining members 8 are arranged in the vertical direction, but the number of mold restraining members 8 is not limited to three, and may be one or two. Four or more is acceptable.

  And the permeability test using the permeability test apparatus comprised as mentioned above is performed like the permeability test method according to the method prescribed | regulated to ASTM D5084 of the American Society for Test Materials, for example. However, the cell pressure in the contents prescribed in ASTM is set to a value that is considered to be larger than the swelling pressure whose actual value is unknown, but in the water permeability test using the water permeability test apparatus of the present invention, the cell pressure Can be set to a value lower than the swelling pressure (in other words, the cell pressure is set independently of the swelling pressure). That is, in the water permeation test apparatus of the present invention, the swelling pressure of the specimen 20 is held by the restraint mold 7 tightened by the mold restraining member 8 and the deformation at the time of swelling of the specimen 20 is limited. Since there is no need to suppress deformation of the specimen 20 during swelling, the pressure for increasing the adhesion between the covering member 10 and the side face of the specimen 20 to the water pressure of the water passage pipe 2 (for example, 0.1 to 0.5). [MPa] should be added as the cell pressure, and when the swelling pressure of the specimen 20 is large, the test should be performed at a cell pressure that is much lower than the cell pressure in the method of ASTM. Can do. In addition, when the swelling pressure of the specimen 20 is smaller than the pressure for increasing the adhesion between the covering member 10 and the side face of the specimen 20, the specimen 20 contracts between the covering member 10 and the constraining mold 7. Since the gap is generated and the swelling pressure does not act on the constraining mold 7, a test similar to ASTM is performed substantially.

  According to the water permeation test method and the water permeation test apparatus configured as described above, the cell pressure is applied through the constraining mold 7 and the covering member 10 is pressed against the specimen 20, so that the covering member 10 is in close contact with the side surface of the specimen 20. As a result, local flow through the boundary surface can be made difficult to occur.

  Moreover, since the deformation at the time of swelling of the specimen 20 is controlled by the constraining mold 7, it is necessary to apply a cell pressure that is considered to be larger than the swelling pressure of the specimen 20 to suppress the deformation at the time of swelling. In other words, since the specimen 20 does not shrink, the density of the sample does not increase, and therefore the change in the water permeability of the sample does not occur.

  Further, since deformation at the time of swelling of the specimen 20 is limited by the constraining mold 7, that is, the specimen 20 does not expand, so that the density of the sample does not decrease, so that the permeability coefficient of the sample does not change. Can be.

  Although the above-described embodiment is an example of a preferred embodiment for carrying out the present invention, the embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. It can be implemented. That is, the main point of the present invention is that the side surface along the one direction (axial direction) of the specimen is restricted by a water-impermeable and flexible covering member while restricting expansion and deformation in one direction (axial direction) of the specimen. A constraining member is disposed on the outer periphery of the covering member to restrict outward displacement in a direction orthogonal to the one direction (direction orthogonal to the axial direction), and a cell pressure is applied to the covering member. The specific embodiment is not limited to the above-described embodiment as long as it satisfies this point by passing water (penetrating) through the specimen.

  For example, in the above-described embodiment, the constraining mold 7 that restricts the expansion and deformation of the covering member 10 is configured as a single member having a single layer structure. The structure is not limited to the above, and it may be a multilayer structure including at least a water-permeable layer in contact with the covering member 10 and a non-water-permeable layer on the outer peripheral side. In this case, in particular, since the rigidity of the outer peripheral layer can be increased, the mechanism (function) corresponding to the mold restricting member 8 in the above embodiment is integrated with the restricting mold 7 in the outer peripheral layer. It may be provided as.

  Further, in the above-described embodiment, the constraining mold 7 is configured to be divided into two by the cut surface in the axial direction, but the con? Guration of the constraining mold 7 is not limited to this. Specifically, for example, it is configured as a cylindrical member, and when the specimen 20 is installed between the upper and lower restraint columns 5A and 5B, it is slid toward the upper restraint column 5A. good.

  In the above-described embodiment, the specimen 20 is installed in the water tank 1 so that the axial center direction of the specimen 20 is the vertical direction, and the water passing direction is the vertical direction. The specimen 20 may be installed in the water tank 1 so that the axial center direction of the specimen 20 is horizontal, and the water flow direction may be horizontal. In addition, when installing so that the axial center direction of the test body 20 may become a horizontal direction, the structure corresponded to the upper and lower side restraint pillars 5A and 5B in the above-mentioned embodiment is the horizontal direction of the main body 1b of the water tank 1. Are provided as left and right constraining pillars that protrude in the horizontal direction toward the inside of the main body 1b. In this case, the mold fixing jig 9 may not be provided.

DESCRIPTION OF SYMBOLS 1 Water tank 1a Top cover 1b Main body 2 Pipe for water flow 3 Pipe for drainage 4 Piping for pressure 5A Upper restraint pillar 5B Lower restraint pillar 6A Upper water-permeable member 6B Lower water-permeable member 7 Restraint mold 8 Mold restraint member 8a Rotating shaft 8b Cap 9 Mold Fixing Jig 10 Covering Member 13 Water 14 Gas 20 Specimen

Claims (6)

  While restricting expansion deformation in one direction of the specimen, a side surface along the one direction of the specimen is surrounded by a non-permeable and flexible covering member, and a restraining member is disposed on the outer periphery of the covering member. A water permeability test method characterized in that water is allowed to flow through the specimen in a state where a displacement outward in a direction perpendicular to the direction is restricted and a cell pressure is applied to the covering member.   The water permeability test method according to claim 1, wherein the covering member is a rubber sleeve.   The water permeability test method according to claim 1, wherein the restraining member includes a plurality of layers of a water permeable layer on the side in contact with the covering member and a layer on the outer peripheral side.   A water tank, an upper restraint column projecting downward from the lower surface of the upper lid of the water tank, a lower restraint column projecting upward from the upper surface of the bottom plate of the water tank, and a lower end surface of the upper restraint column and being arranged at the upper end of the specimen A lower water-permeable member that abuts the upper water-permeable member and the upper-side surface of the lower restraining column and is disposed at the lower end of the specimen; and a non-water-permeable and flexible covering member that surrounds the side surface of the specimen And a constraining mold disposed in contact with the outer periphery of the covering member, and allowing water to flow through the specimen in a state in which cell pressure is applied to the covering member with water stored in the water tank. A water permeability test apparatus characterized by that.   The water permeability test apparatus according to claim 4, wherein the covering member is a rubber sleeve.   The water permeability test apparatus according to claim 4, wherein the constraining mold is composed of a plurality of layers of a water permeable layer on the side in contact with the covering member and a layer on the outer peripheral side.

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