JP6277515B2 - Permeability evaluation apparatus and permeation performance evaluation method - Google Patents

Description

  The present invention relates to a water permeation performance evaluation apparatus that evaluates the water permeation performance of a low water permeability material covering a member in a disposal facility such as radioactive waste or industrial waste.

  The present invention also relates to a water permeation performance evaluation method for evaluating the water permeation performance of a low water permeability material which is a material for covering a member to be shielded.

  For example, when disposing of radioactive waste, construction of cover soil or the like using a low water permeability material is being studied in order to suppress the movement of nuclides due to the flow of groundwater. As the low water permeable material, use of a bentonite-based material having extremely low water permeability, for example, bentonite or a material obtained by mixing bentonite and sand has been studied (for example, Patent Document 1). Bentonite is a material that fills gaps by swelling with water absorption, and is a material that exhibits extremely low water permeability when compacted. Therefore, movement of groundwater is suppressed, reducing the impact of radioactive waste on the living environment. can do.

  In order to ensure that the movement of nuclides due to the flow of groundwater is at a problem-free level for a long period of time, it is necessary to accurately evaluate the water permeability of the low water permeability material. A material with extremely low water permeability such as bentonite is often regarded as substantially water-impermeable from the viewpoint of a general earth structure, and rigorous evaluation is rarely required.

  However, when bentonite materials are used in radioactive waste disposal facilities, it is necessary to accurately grasp even the movement of extremely low amounts of water, and it is hoped that the permeability of bentonite materials will be strictly evaluated. It is rare. In particular, it is difficult to saturate a low water permeable material, and if air remains, movement of a very small amount of water is hindered, and there is a concern of underestimating the water permeability. The sophistication of is essential.

Japanese Patent Laid-Open No. 2003-255087

  The present invention has been made in view of the above situation, and a water permeation performance evaluation apparatus and a water permeation performance capable of appropriately measuring the movement of a very small amount of water and evaluating the water permeation even with a material having a very low water permeability. The purpose is to provide an evaluation method.

  In order to achieve the above object, the water permeation performance evaluation apparatus of the present invention according to claim 1 is a low water permeation performance evaluation apparatus for a low water permeation material that evaluates the water permeation performance of a low water permeation material that covers a covering object. A pair of perforated plate members holding a pair of opposed surfaces, a water supply path connected to one of the perforated plate members, a drainage path connected to the other perforated plate member, and a water supply amount supplied to the water supply path Low based on the inflow rate measurement means to measure, the outflow rate measurement means to measure the amount of drainage discharged from the drainage path, the amount of water supply measured by the inflow rate measurement means, and the amount of drainage measured by the outflow rate measurement means Saturation judgment means for judging the water saturation of the water permeable material, and water permeability performance evaluation means for evaluating the water permeability performance of the low water permeability material when the saturation judgment means determines that the low water permeability material is saturated with water. And with saturation The disconnecting means has an opening / closing means for opening and closing the drainage path and a water supply pressure adjusting means for adjusting the pressure of the water supply, and the drainage path is closed by the opening and closing means and the water supply pressure is raised by the water supply pressure adjustment means, It is characterized in that it is judged that the water of the low water permeable material is saturated when water supply becomes impossible.

  In the present invention according to claim 1, when the drainage path is closed by the opening / closing means, water is injected from the water supply path at one end of the low water permeable material, and when the water does not flow from the water supply path, the saturation judgment is made. It is judged that there is no air remaining in the low water permeable material by means, and the low water permeable material is saturated with water. Evaluate the water permeation performance of low water permeability materials (for example, cover soil, bottom impermeable material, vertical impermeable wall material).

  Therefore, after the inside of the low water permeable material is saturated with water, the water permeability of the low water permeable material can be evaluated, and the influence that the air existing in the low water permeable material inhibits the water permeability is eliminated. Only the water flow condition can be judged. For this reason, even if it is a low water-permeable material with extremely low water permeability, it becomes possible to grasp the movement of a very small amount of water and evaluate water permeability.

  And the water-permeable performance evaluation device of the present invention according to claim 2 is the water-permeable performance evaluation device according to claim 1, wherein the saturation judging means raises the water supply pressure in a plurality of stages by the water supply pressure adjusting means. It is characterized by judging the saturation situation of water.

  In this invention which concerns on Claim 2, when saturating the inside of a low water-permeable material with water, a saturated state can be judged by injecting water with the water supply pressure of several steps, and water permeability can be evaluated.

Further , the water permeation performance evaluation apparatus according to the present invention is the water permeation performance evaluation apparatus according to claim 1 or claim 2, wherein the saturation judging means adjusts the state of the outflow pressure of the water in the drainage path to adjust the low water permeability material. It has a back pressure adjusting means for adjusting the internal pressure, and once the saturated state is judged, the feed water pressure is raised by the feed water pressure adjusting means, and the water flow resistance of the drainage path is reduced by the back pressure adjusting means. It is preferable that the saturation state of the low water-permeable material is determined by raising the level .

As a result, after the saturation state is determined, the water supply pressure is increased and the drainage water resistance is increased (back pressure is increased), and the internal pressure of the low water permeable material is uniformly increased. Evaluation of water permeability of low water permeability material. Therefore, even when the dissolved air of water accumulates in the low water permeable material once the saturated state is determined, it is possible to determine the saturated state and the water permeable state in a state where the influence of air preventing water permeability is eliminated.

In order to achieve the above object, the water permeability evaluation method of the present invention according to claim 3 is the water permeability performance evaluation method for evaluating the water permeability of the material covering the member to be shielded. Injecting and draining the injected water from the outlet portion at the other end of the material, when evaluating the water permeability, stopping drainage from the outlet portion and injecting water from the inlet portion, It is judged that the inside of the covering material is saturated with water when water does not flow from the inlet portion, and drainage is performed from the outlet portion after the saturated state is judged to evaluate the water permeability performance. And

In this invention which concerns on Claim 3 , after the inside of the material (low water-permeable material: For example, a cover soil, a bottom water-impervious material, a vertical water-impervious wall material) which covers a to-be-shielded member is saturated with water, a water-permeable state is judged. Therefore, it is possible to determine the water flow state by eliminating the influence of air existing in the material. For this reason, even if it is a material with very low water permeability, it becomes possible to evaluate water permeability by measuring the movement of a very small amount of water.

And the water-permeable performance evaluation method of the present invention according to claim 4 is the water-permeable performance evaluation method according to claim 3 , wherein when water is injected from an inlet portion at one end of the material, water is injected at a plurality of stages of pressure. It is characterized by press fitting.

In the present invention according to claim 4 , when saturating the material with water, water can be injected with a plurality of stages of pressure to determine a saturated state, and water permeability can be evaluated.

Further, the water permeability evaluation method of the present invention according to claim 5 is the water permeability performance evaluation method according to claim 3 or 4 , wherein when drainage is performed from the outlet after the saturated state is determined, The water permeation performance is evaluated by increasing the pressure of water injected from the inlet.

In this invention which concerns on Claim 5 , after judging a saturated state, water can be passed through a material comparatively easily.

Further, the water permeability evaluation method of the present invention according to claim 6 is the water permeability performance evaluation method according to any one of claims 3 to 5 , wherein the inflow / outflow flow rate is constant after the saturated state is determined. Ensure that became, injection pressure from the inlet, and, after raising the drainage pressure from the outlet at the same time, and evaluating a water permeability.

With the present invention according to claim 6, after the saturation has been determined, injection pressure from the inlet, and, after raising the drainage pressure from the outlet at the same time, since to evaluate the water permeability, once the saturation Even when the dissolved air of water enters and accumulates in the material after the determination, the saturation state can be determined in a state in which the influence of the air preventing water permeation is eliminated.

Further, water permeability evaluation method of the present invention according to claim 7, in water permeability evaluation method according to any one of claims 6 claim 3, wherein the water permeability to be evaluated, the flow rate for the water flow pressure The hydraulic conductivity is calculated based on the relationship. The water permeability evaluation method of the present invention according to claim 8 is the water permeability evaluation method according to any one of claims 3 to 7 , wherein the material is a material containing bentonite. And

In the present invention according to claim 7 , the water permeation performance can be evaluated by the water permeation coefficient calculated based on the water flow pressure (dynamic gradient) and the flow rate (flow velocity) which is the water flow rate per unit time. Moreover, in this invention which concerns on Claim 8 , the water-permeable performance of the low water-permeable material containing bentonite can be evaluated accurately.

  The water permeability evaluation apparatus of the present invention can evaluate the water permeability by grasping the movement of a very small amount of water even with a low water permeability material having extremely low water permeability.

  In addition, the method for evaluating water permeability according to the present invention can evaluate water permeability by measuring the movement of a very small amount of water after appropriately saturating a specimen even if the material has extremely low water permeability. .

It is a schematic block diagram of the water-permeable performance evaluation apparatus which concerns on one Example of this invention which implements the water-permeable performance evaluation method which concerns on one Example of this invention. It is principle explanatory drawing of a feed water pressure adjustment means and a back pressure adjustment means. It is operation | movement explanatory drawing of a water-permeable performance evaluation apparatus. It is operation | movement explanatory drawing of a water-permeable performance evaluation apparatus. It is operation | movement explanatory drawing of a water-permeable performance evaluation apparatus. It is operation | movement explanatory drawing of a water-permeable performance evaluation apparatus. It is a graph explaining the relationship between feed water pressure, back pressure, and flow volume.

  In a radioactive waste disposal facility, it is considered to cover a member of the facility with a low water permeability material having extremely low water permeability. As a low water permeable material, use of a mixed material of bentonite and sand has been studied. The water permeation performance evaluation device of the present invention is an evaluation device and an evaluation method for strictly evaluating the water permeation performance of a material (test body: low water permeability material) in which bentonite and sand are extremely low in water permeability.

  A specimen made of a material in which bentonite and sand are mixed is formed in a cylindrical shape having a predetermined size, and its water permeability is evaluated based on the pressure and water flow rate when water is sent in the axial direction. In this case, if air exists in the specimen and is in an unsaturated state, the water channel inside the specimen may be blocked by the air, resulting in an inappropriate water flow state. It can be considered that it varies depending on the time. For this reason, the water permeation performance evaluation apparatus and the water permeation performance evaluation method of the present invention evaluate the water permeation performance in a state where the inside of the test body is saturated with water.

  As a result, the influence of air existing inside the test specimen can be eliminated and only the water flow state can be determined. Even a test specimen made of a low water permeability material with extremely low water permeability can use a very small amount of water. It becomes possible to grasp the movement of the water and evaluate the water permeability.

  A water permeation performance evaluation apparatus will be described with reference to FIG.

  FIG. 1 shows a cross-sectional view schematically illustrating a water permeation performance evaluation apparatus according to an embodiment of the present invention.

  The water permeation performance evaluation apparatus 1 has a stainless steel cell 2 and a stainless steel discharge base 3 installed on top of the cell 2. A test body ring 4 is provided between the cell 2 and the discharge base 3, and a cylindrical test body 5 (low water-permeable material) is held inside the test body ring 4.

  The upper surface of the cell 2 inside the test body ring 4 is provided with a porous metal plate 6 (perforated plate member) that comes into contact with the lower end surface of the test body 5, and on the lower surface side of the discharge base 3 inside the test body ring 4. Is provided with a porous metal plate 7 (a porous plate member) in contact with the upper end surface of the test body 5.

  By attaching the discharge base 3 to the cell 2 in a predetermined state, the test body 5 is set in the water permeation performance evaluation apparatus 1. That is, by inserting the test body 5 into the test body ring 4 and fixing the discharge base 3 to the cell 2 in a predetermined state, the upper and lower end surfaces of the test body 5 are in surface contact with the porous metal plates 6 and 7. Then, the test body 5 is held and the test body 5 is set in the water permeation performance evaluation apparatus 1.

  A water supply path 11 (water supply path) is connected to the porous metal plate 6 provided in the cell 2. By supplying water from the supply path 11 to the porous metal disk 6, the water spreads evenly on the surface of the porous metal disk 6 and is supplied to the lower end surface of the test body 5 in an even state.

  The supply path 11 is provided with an inlet three-way valve 12, and the first inlet path 13 of the inlet three-way valve 12 is provided with inflow rate detection means 14 (inflow rate measurement means) for detecting the flow rate of supplied water. Yes. The inflow flow rate detection means 14 is connected with a water supply pressure adjustment means 15 for supplying water of a predetermined pressure. An inlet suction means 17 (suction pump) is connected to the second inlet passage 16 of the inlet three-way valve 12, and a suction force acts on the porous metal plate 6 (test body 5) by driving the inlet suction means 17. 5 is degassed.

  A water discharge path 21 (drainage path) is connected to the porous metal board 7 provided in the discharge base 3, and water that has been permeated through the porous metal board 7 in a uniform state is collected in the discharge path 21 and discharged. Is done. The discharge path 21 is provided with an open / close valve 22 (open / close means), and an outflow flow rate detection means 23 (outflow flow rate measurement means) for detecting the flow rate of discharged water is provided at the end of the open / close valve 22. Yes.

  An outlet three-way valve 24 is provided on the outlet end side of the outflow flow rate detection means 23, and discharged water is sent from a first outlet passage 25 of the outlet three-way valve 24 to a recovery unit (not shown). A drain pressure adjusting means 27 that increases the outflow resistance of water in the discharge path 21 (increases the back pressure) is connected to the second outlet path 26 of the outlet three-way valve 24. When the water supply pressure on the inlet side is increased, the back pressure is increased by the drainage pressure adjusting means 27.

  Based on FIG. 2, the concept of the water supply pressure adjusting means 15 and the drain pressure adjusting means 27 will be described.

  A supply water pressure adjusting means 15 is connected to the supply path 11, and a drain pressure adjusting means 27 is connected to the discharge path 21. The water supply pressure adjusting means 15 and the drainage pressure adjusting means 27 are provided with a cylindrical container filled with water, and air pressure is applied to the cylindrical container, whereby a predetermined pressure is applied to the supply path 11 and the discharge path 21. Pump water with

  For example, by adjusting the air pressure of the feed water pressure adjusting means 15, water having a predetermined pressure (AkPa) is sent to the supply path 11, and water having a predetermined pressure is supplied to the porous metal disk 6. At the same time, by adjusting the air pressure of the drain pressure adjusting means 27, water having a predetermined pressure (BkPa: A> B) is sent to the discharge path 21, and the outflow resistance of the water in the discharge path 21 is increased. The pressure is increased. That is, the pressure in the test body 5 is uniformly increased by BkPa.

  From the discharge path 21, water having a pressure difference between the supply pressure from the feed water pressure adjusting means 15 and the pressure at the flow end side applied to the discharge path 21 is discharged. Here, since the pressure at the end of the flow is equal to the pressure that uniformly increases inside the test body 5, the pressure at the end of the flow is equal to the back pressure.

  For example, the cylindrical container is composed of a double tube, water is put on the outside and inside, air pressure of a constant pressure acts on both sides, and the inside water is discharged and sent to the test body 5 is adopted. . When the pressure is constantly applied to the double pipe, the volume of the inner container is not changed, and the water in the cylindrical container is less likely to evaporate and a small amount of water is supplied. Even the effects of evaporation can be reduced.

  In addition, it is also possible to set it as a flow volume detection means by attaching a scale to a cylindrical container and managing the quantity of water based on a scale.

  Returning to FIG. 1, the description of the water permeation performance evaluation apparatus will be continued.

  The water permeation performance evaluation apparatus 1 is provided with a pressure detection means 31 for detecting the pressure of the test body 5, the water pressure inside the test body 5 is detected by the pressure detection means 31, and the progress of deaeration of the test body 5 The difference from the atmospheric pressure can be quantitatively confirmed.

  Although the figure shows a state in which the pressure detection means 31 is directly connected to the test body 5, for example, the pressure of the supply path 11 is detected by the pressure detection means 31, and the water pressure inside the test body 5 is detected. It is supposed to be. It is also possible to directly detect the water pressure of the test body 5.

  Further, the cell 2 of the water permeation performance evaluation apparatus 1 is provided with a load cell 32 (load meter), and the swelling pressure of the test body 5 is measured by the load cell 32 so that the state of swelling of the test body 5 can be confirmed. For example, it can be determined that the bentonite-based material is almost saturated based on the fact that the swelling pressure of the test body 5 has become steady. The water permeation performance evaluation apparatus 1 includes a control device 35 to which detection information of the inflow flow rate detection means 14, the outflow flow rate detection means 23, and the pressure detection means 31 is input.

  In response to a command from the control device 35, the switching of the first inlet passage 13 and the second inlet passage 16 of the inlet three-way valve 12, the operation of the feed water pressure adjusting means 15 (air pressure adjustment), and the driving of the inlet suction means 17 are controlled. Control is implemented. Further, in accordance with a command from the control device 35, the opening / closing control of the opening / closing valve 22, the switching control of the first outlet passage 25 and the second outlet passage 26 of the outlet three-way valve 24, the operation of the drain pressure adjusting means 27 (pneumatic pressure) Adjustment) is performed.

  The controller 35 recognizes the state of water pressure in the test body 5 and the state of water that passes through the test body 5 based on the detection information of the inflow flow rate detection means 14, the outflow flow rate detection means 23, and the pressure detection means 31. In addition, a saturation judgment function (saturation judgment means) for judging whether or not the inside of the test body 5 is saturated with water is provided. Furthermore, the control device 35 has a permeability coefficient judgment function (permeability evaluation) that guides the permeability state (permeability coefficient) based on the pressure for passing water through the test body 5 and the amount of water flowing into and out of the test body 5. Means).

  The control device 35 determines the water permeability coefficient derived by the water permeability coefficient determination function as the water permeability coefficient of the test body 5 when the saturation determination function confirms that the inside of the test body 5 is saturated with water. Judgment function is provided. In the determination function, the water permeability coefficient after determining the saturation is determined in consideration of the state of the swelling pressure and the gap pressure of the test body 5 measured by the load cell 32.

  Based on FIG. 3 to FIG. 7, a water permeation performance evaluation method according to an embodiment of the present invention by the water permeation performance evaluation apparatus 1 having the above-described configuration will be described.

  FIG. 3 to FIG. 6 are diagrams for explaining the operation in a state where the water permeation performance evaluation method is performed, and FIG. 7 is a graph for explaining the relationship between the water supply pressure, the back pressure and the flow rate.

  A specific procedure will be described with reference to FIGS.

  In order to prevent fine particles from flowing out of the apparatus due to the flow of water on the upper and lower end faces of the test body 5, a polymer filter having a fine pore diameter is laid, and the test body 5 is arranged on the test body ring 4 in the cell 2. The discharge base 3 is fixed, and the test body 5 is installed in the water permeation performance evaluation apparatus 1.

  As shown in FIG. 3, the on-off valve 22 is closed and the inlet three-way valve 12 is switched to the second inlet passage 16 side. The inlet suction means 17 is driven to depressurize the inside of the test body 5 (vacuum), and the test body 5 is deaerated while maintaining a vacuum atmosphere for a predetermined time.

  As shown in FIG. 4, the inlet three-way valve 12 is switched to the first inlet passage 13 side, and the water supply pressure adjusting means 15 is operated (air pressure is adjusted) to supply water from the supply passage 11. The deaerated ion exchange water is applied to the supplied water, and the supply amount is measured by the inflow rate detection means 14. The pressure detection means 31 confirms that the inside of the test body 5 has become atmospheric pressure (0 kPa: gauge pressure), and the inflow rate detection means 14 confirms that a predetermined amount of water has been supplied.

  As shown in FIG. 5, the on-off valve 22 is opened and the outlet three-way valve 24 is switched to the first outlet path 25 side. The inflow flow rate detection means 14 measures the feed water flow rate, and the outflow flow rate detection means 23 measures the discharged water flow rate.

  When the discharge water flow rate measured by the outflow flow rate detection means 23 is smaller than the feed water flow rate measured by the inflow flow rate detection means 14, air is present inside the test body 5 and is not saturated with water. It is judged.

  When the supply water flow rate measured by the inflow flow rate detection means 14 and the discharged water flow rate measured by the outflow flow rate detection means 23 coincide with each other, it is estimated that the water inside the test body 5 is almost saturated. Moreover, when it is measured by the load cell 32 that the swelling pressure of the test body 5 becomes constant, it is estimated that the water in the test body 5 is almost saturated.

  In this state, the on-off valve 22 is closed (the state shown in FIG. 4), and the water supply pressure is increased to check whether or not the state is saturated. That is, when the water supply pressure is increased with the on-off valve 22 closed, if water is supplied, air is present in the specimen 5 and the amount of water supplied is measured. To evaluate the saturation state. If water is not supplied even when the water supply pressure is increased, it is determined that the state is saturated.

  In a state where it is determined that the inside of the test body 5 is saturated with water, as shown in FIG. 5, the on-off valve 22 is opened, and the water permeability is evaluated based on the water supply pressure and flow rate at that time. In this case, it is also possible to evaluate the water permeability by increasing the feed water pressure in a plurality of stages (increasing the water press-in pressure), that is, by increasing the hydraulic gradient.

  As a result, the influence of the air existing inside the test body 5 can be eliminated and only the water flow state can be determined. Even in the case of the test body 5 which is a material with extremely low water permeability, the material is made of water. It becomes possible to saturate appropriately and grasp the movement of a very small amount of water to accurately evaluate water permeability.

  And when saturating the inside of the test body 5 of a low water-permeable material with water, since water is inject | poured by the pressure of several steps, a saturated state can be judged at an early stage and water permeability (water permeability coefficient) is early. Can be evaluated.

  When confirming that the hydraulic conductivity is certain, it is confirmed that the inflow / outflow flow rate has become constant (after the saturation state is judged), and the outlet three-way valve 24 is connected to the second outlet passage as shown in FIG. 26, the feed water pressure is increased stepwise by the feed water pressure adjusting means 15, and the back pressure of the discharge passage 21 is raised stepwise by the drain pressure adjusting means 27 so that the differential pressure is the same.

  By increasing the supply pressure and the back pressure of the discharge path 21, the pressure inside the test body 5 can be uniformly increased with the differential pressure kept constant. Even when the dissolved air enters and accumulates in the test body 5, the saturation state can be determined in a state where the influence of the air hindering the water permeation path is eliminated.

  For example, the feed water pressure by the feed water pressure adjusting means 15 is increased stepwise to 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.7 MPa, 0.9 MPa, and 1.1 MPa. At the same time, the pressure of the discharge path 21 (pressure at the end of the flow) by the drain pressure adjusting means 27 is increased to 0 MPa, 0.2 MPa, 0.4 MPa, 0.6 MPa, 0.8 MPa, and 1.0 MPa. That is, the feed water pressure and the pressure at the end of the flow are increased stepwise so that the differential pressure is maintained at 0.1 MPa.

An example of the relationship between the feed water pressure (MPa) and the pressure at the end of the flow (MPa) and the flow rate Q (m ³ / s) is shown in FIG. The pressure when the pressure on the flow end side becomes equal to the pressure uniformly increased inside the test body 5 is called back pressure.

  As shown in the figure, when the feed water pressure is 0.1 MPa and the end-side pressure is 0 MPa, the flow rate Q is Q0, and the feed water pressure is gradually increased to 0.3 MPa, 0.5 MPa, and 0.7 MPa. At the same time, the flow rate Q is increased from Q0 to Q1 by gradually increasing the pressure on the flow end side to 0.2 MPa, 0.4 MPa, and 0.6 MPa. Thereafter, at the feed water pressure of 0.7 MPa, the pressure at the end of the flow, that is, the pressure after the back pressure of 0.6, the state where the differential pressure is 0.1 MPa and the flow rate Q is Q1 is maintained.

  This is because once the saturation state is judged, the dissolved air of water enters the test body 5 (low permeability cover) and the flow rate Q is reduced to Q0, and the pressure on the end of the flow is increased. Thus, it can be said that the back pressure has increased, the air that has entered is compressed, and the flow rate Q is increased to Q1, which is the flow rate Q in the original saturated state.

  Thereby, even if the dissolved air of water once entered the test body 5 after the saturated state was judged, the water supply pressure was increased to 0.7 MPa, and the back pressure was increased to 0.6 MPa. It turns out that it becomes possible to make it the state which excluded air.

  The water permeability coefficient of the test body 5 in the state where the influence of air is eliminated can be evaluated by the relationship of the flow rate Q1 to the pressure of 0.1 MPa, which is the differential pressure between the feed water pressure and the pressure at the end of the flow.

  That is, the water permeability can be evaluated in a state where the feed water pressure is raised by the feed water pressure adjusting means 15 and the back pressure of the discharge path 21 is increased by the drain pressure adjusting means 27 to eliminate the influence of dissolved water. .

  For convenience of explanation, the water supply pressure is exemplified as 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.7 MPa, 0.9 MPa, 1.10 MPa, and the back pressure is 0 MPa, 0.2 MPa, 0.4 MPa, 0, Although illustrated as 0.6 MPa, 0.8 MPa, and 1.0 MPa, the actual pressure value is determined in consideration of the type of material, the amount of air present in the test body 5, and the performance of the apparatus.

  If the specimen 5 of the low water permeability material mixed with bentonite and sand is in an unsaturated state, there is a risk that the water channel inside the specimen will be blocked by air and the water flow will be inappropriate. It is conceivable that the swelling state of 5 also varies with time. In the water permeability evaluation apparatus 1 of the low water permeability material described above, the water permeability is evaluated in a state where the inside of the test body 5 is saturated with water. It is possible to evaluate the water permeability coefficient by eliminating the influence of the change in the water permeability or the change in the water permeability due to the change of the swelling state.

  Since the water permeability evaluation apparatus 1 described above evaluates the water permeability coefficient in a state in which the inside of the test body 5 is saturated with water, the influence of air existing inside the test body 5 is eliminated and the water permeability is evaluated. It is possible to judge only the water flow state of the water, and even the test body 5 of a low water permeability material having extremely low water permeability can grasp the movement of a very small amount of water and accurately evaluate the water permeability coefficient. Become.

  Moreover, even if it is the test body 5 of the low water permeability material with very low water permeability, the water permeability evaluation method mentioned above evaluates a water permeability coefficient by measuring the movement of a very small amount of water after appropriately saturating with water. It becomes possible.

  The present invention can be used in the industrial field of a water permeation performance evaluation apparatus and a water permeation performance evaluation method.

DESCRIPTION OF SYMBOLS 1 Permeability evaluation apparatus 2 Cell 3 Discharge base 4 Test body ring 5 Test body 6 and 7 Porous metal plate 11 Supply path 12 Inlet three-way valve 13 1st inlet path 14 Inflow flow rate detection means 15 Supply water pressure adjustment means 16 2nd inlet Path 17 inlet suction means 21 discharge path 22 on-off valve 23 outflow flow rate detection means 24 outlet three-way valve 25 first outlet path 26 second outlet path 27 drainage pressure adjustment means 31 pressure detection means 32 load cell 35 control device

Claims (8)

In the water permeation performance evaluation device for a low water permeability material that evaluates the water permeability of the low water permeability material that covers the covering object
A pair of perforated plate members holding a pair of opposed surfaces of a low water permeable material;
A water supply path connected to one of the porous plate members;
A drainage path connected to the other porous plate member;
Inflow flow rate measuring means for measuring the amount of water supplied to the water supply path;
Outflow flow rate measuring means for measuring the amount of drainage discharged from the drainage route,
Saturation judgment means for judging the saturation state of the water of the low water permeability material based on the amount of water supply measured by the inflow flow rate measurement means and the amount of drainage measured by the outflow flow rate measurement means,
When it is determined by the saturation determining means that the low water permeable material is saturated with water, the water permeable performance evaluating means for evaluating the water permeable performance of the low water permeable material,
Saturation judgment means
Opening and closing means for opening and closing the drainage path;
Water supply pressure adjusting means for adjusting the pressure of the water supply,
A water permeability evaluation device characterized by determining that the low water permeability material is saturated with water when water supply cannot be performed with the drainage path closed by the opening and closing means and the water supply pressure increased by the water supply pressure adjustment means. . In the water-permeable performance evaluation apparatus according to claim 1,
Saturation judgment means
A water permeation performance evaluation apparatus characterized in that a water supply pressure is raised in a plurality of stages by a water supply pressure adjusting means to judge a water saturation state of a low water permeability material. In the method for evaluating the water permeability of the low water permeability material for evaluating the water permeability of the low water permeability material covering the covering object,
In evaluating water permeability performance by injecting water from an inlet portion at one end of the low water permeability material and draining the injected water from an outlet portion at the other end of the low water permeability material,
Stopping the drainage from the outlet part and press-fitting water from the inlet part, when the water does not flow from the inlet part, it is determined that the low water permeable material is saturated with water,
After the saturated state is judged, drainage is performed from the outlet portion to evaluate the water permeability. A method for evaluating the water permeability of a low water permeability material. In the method for evaluating water permeability of the low water permeability material according to claim 3,
A method for evaluating water permeability of a low water permeability material, wherein water is injected at a plurality of stages of pressure when water is injected from an inlet at one end of the low water permeability material. In the method for evaluating water permeability of the low water permeability material according to claim 3 or 4 ,
When draining from the outlet portion after the saturated state is judged, the water permeability performance is evaluated by increasing the pressure of water injected from the inlet portion. In the water permeability evaluation method of the low water permeability material according to any one of claims 3 to 5 ,
After the saturated state is determined, the inflow outflow rate confirms that became constant, injection pressure from the inlet, and, after high flow resistance of water in the outlet portion, to evaluate the water permeability A method for evaluating the water permeability of a low water permeability material. In the water permeability evaluation method of the low water permeability material according to any one of claims 3 to 6 ,
The method for evaluating water permeability of a low water permeability material, wherein the water permeability performance to be evaluated is a water permeability coefficient calculated based on a relationship of a flow rate with respect to a water flow pressure. In the water permeability evaluation method of the low water permeability material according to any one of claims 3 to 7 ,
The low water-permeable material is a material containing bentonite. The method for evaluating water-permeable performance of a low water-permeable material.

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