JP4587054B2 - Test method for poorly water-permeable soil materials - Google Patents

Description

  The present invention relates to a test method for a very low permeability permeable soil material including a clay material having water-absorbing expansibility, and in particular, it is difficult to easily and quickly confirm the permeability and permeability characteristics of the hardly permeable soil material. The present invention relates to a test method for permeable soil material.

  When embedding industrial waste or radioactive waste in the ground, it is effective to stop the water with a waste filler made of a soil material with a very low permeability, and knead bentonite-based materials and aggregates. Thus, a poorly water-permeable soil material using a material that has been compacted at high density or a material that is compacted from bentonite alone, and a soil material having a water permeability of 1E-8 m / s or less is used.

  A representative example of the hardly permeable soil material is bentonite. Bentonite has a water permeability of 1E-10 m / s to 1E-14 m / s at a dry density of 1500 to 2000 kg / m3, and has similar water impermeability even in an unsaturated state.

  Such an extremely small water permeability coefficient is caused by the effect of minimizing the pore diameter generated by the water absorption and expansion of smectite clay particles in bentonite. That is, bentonite has a relatively large water permeability coefficient immediately after water injection because the water absorption and expansion action of smectite clay particles does not work in a completely dry state. However, since smectite clay particles start to absorb water in a few seconds or minutes, the period when the water permeability coefficient is relatively large is very short, and thereafter, the poor permeability of bentonite is secured.

Thus, the hardly water-permeable soil material that is rolled on site has an optimum water content with the least amount of rolling energy, but the water content is neither completely dry nor completely saturated.
For this reason, in the poorly water-permeable soil material mainly composed of bentonite, the water content ratio is generally adjusted to a range of about 10% to about 25% and then rolled or press-molded, and compressed by a press device. Although it is created after adjusting to an appropriate amount of water for molding, the poorly water-permeable soil material adjusted to such a moisture content contains smectite clay that exhibits moderate water absorption expansion, This is because when the compaction or press molding is performed at a high density, the workability is good in order to exhibit a suitable viscosity.

In such materials, most of the smectite clay particles exhibit water absorption and expansion, and water and air are sparsely present in the gaps between the soil particles. Water does not readily penetrate even when injected.
However, the poorly permeable soil material does not show a correct hydraulic conductivity when not saturated with water, whereas the bentonite high-density solidified material constituting the waste filler has a long time after construction. Since it will be saturated with water after passing through, barrier functions such as water shielding performance and radionuclide delay performance over a long period of time need to be specified in a saturated state, and will be confirmed in a short time after construction It is demanded.

  However, since hardly permeable soil materials are installed around the waste buried underground, it is necessary to measure various characteristics such as permeability coefficient, diffusion coefficient, and mechanical characteristics in a state saturated with water. In order to saturate the test specimen with water, high-pressure water is injected into the specimen because the permeability coefficient of the permeable soil material is 1E-8 m / s to 1E-14 m / s, which is very difficult to permeate. Therefore, it is necessary to bring the water into a saturated state while gradually infiltrating water, and the actual situation is that it takes a long period of one month or more.

  That is, if it is a bentonite material having a dry density of 1600 kg / m3, the water permeability is 1E-13 m / s, and the size of the specimen is 50 mmφ × 50 mmH, the porosity is about 30%, which is 30 ml, which is suitable for construction. When rolling at a water content ratio, the saturation is about 80%, so the volume of air remaining in the specimen is around 6 ml, and water is infiltrated into the specimen at a pressure of 10 atm. Then, the amount of intrusion water required to saturate the specimen is calculated as follows.

  Therefore, it took 173 days for the specimen having a height of 50 mm to be saturated.

・ Q = k ・ i ・ A
= 1E-13 × 100 / 0.05 × 0.002 × 3600 × 24 × 1000000 = 0.0346 ml / day T = 6 ml ÷ 0.0346 ml / day = 173 days

  For this reason, when reflecting it in the design of the facility, it is possible to obtain material characteristics by giving a margin to the preliminary test schedule, but in the case of constructing these members on site, Since it is necessary to acquire quality test data of construction materials in a short time for quality and control, a water permeability test that can be quickly dealt with is required.

  In addition, there is an air permeability test as a similar test for poorly water-permeable soil materials, but this test is also a test for grasping the characteristics of gas permeability using the hardly water-permeable soil material saturated with water. Therefore, it is effective to reduce the time required for saturation of the specimen in a short time as in the water permeability test.

  As described above, as a specimen for carrying out the water permeability / air permeability test and the mechanical test, it is necessary to gradually infiltrate while injecting high-pressure water into the hardly water-permeable soil material and to be saturated. When air is included, it is difficult to pursue characteristics that can maintain the barrier function such as the target water shielding performance and radionuclide delay performance over a long period of time. The establishment of the method was envied.

  As general water permeation and air permeation devices, those used for the test of water permeation pavement are introduced as follows, but the target specimen is a paved road, so the level of water permeation characteristics is completely different. Therefore, the conventional example of the present invention has no room for consideration.

JP-A-902-64588 (third page, identification code “006” to fourth page, last line of identification code “009”, FIGS. 1 and 2)

  Accordingly, the present inventors have already proposed a waste filler made of a soil material with a low hydraulic conductivity that can be employed when industrial waste or radioactive waste is buried in the ground, and a device for manufacturing the same (patent application). 902-63838) and proposals on water permeability and air permeability test methods for bentonite high density solidified bodies produced here (Japanese Patent Application No. 903-25952). For quality control, it is necessary to acquire quality test data of construction materials with higher accuracy in a shorter time, and therefore a water permeability test method capable of coping with speed and accuracy is required.

  The present invention is proposed in view of the above situation, and the hardly water-permeable soil material used for each characteristic test such as diffusion property, water permeability property, air permeability property and mechanical property performed on the hardly water-permeable soil material. The test piece was completely infused with high-pressure water while removing the air contained in it to complete the moisture saturation process in a short time. A method for testing a hardly water-permeable soil material that can be carried out quickly is provided.

The method for testing a hardly water-permeable soil material according to claim 1 is a first step in which a specimen of a hardly water-permeable soil material loaded in a test container is installed in a test device, and evaporates moisture in the specimen. the second step of removing the third step of Genchijimi the air layer in the specimen by vacuum after the second step, a fourth step of infiltrating water into specimens by injecting high pressure water from the injection tube, the test It comprises the fifth step of performing a predetermined characteristic test after connecting an appropriate measuring instrument to the apparatus.

  Accordingly, the test method according to the present invention evaporates and removes moisture from the specimen of the hardly permeable soil material, and then injects high-pressure water into the air layer in the reduced specimen to cause water to enter the specimen. The specimen is saturated with water by infiltration, and moisture saturation of the specimen is completed quickly and with high density, enabling the subsequent performance tests to be carried out smoothly.

  The test method for a hardly water-permeable soil material according to claim 2 is the test method according to claim 1, wherein the second step is to move the test apparatus to a high-temperature drying furnace and heat the sample while heating at high temperature. In addition to the above function, the moisture in the specimen is removed by evaporation while heating at a high temperature, so that the moisture saturation of the specimen is made more rapid and dense.

  The test method of the hardly water-permeable soil material which is the invention described in claim 3 is the test method according to claim 1, wherein the second step is vacuum evaporation of the water in the specimen by evacuating the test apparatus. In addition to the above functions, the air is removed by evacuation, and the moisture in the specimen is removed by vacuum evaporation, so that the moisture saturation of the specimen can be made more rapid and dense. Yes.

A test method for a hardly water-permeable soil material according to a fourth aspect of the present invention is the test method according to any one of the first to third aspects, wherein the third step is a step of supplying water from the injection tube to the test device. by injecting the gender gases, then are characterized and Turkey to leave only water-soluble gas lean trace by vacuuming, in addition to the above functions, the water gas was filled in the air layer formed by reduction Thus, only a small amount of water-soluble gas is left in the specimen of the hardly permeable soil material, so that the moisture saturation of the specimen is made more rapid and dense.

The test method for a hardly water-permeable soil material according to claim 5 is the test method according to any one of claims 1 to 3, wherein a water-soluble gas is filled after the third step. , the following are characterized by vacuum to the in specimen further comprises the step of leaving only a water-soluble gas lean traces by removing the air, in addition to the above functions, specimens of low permeability soil material In addition, only a water-soluble gas is allowed to remain in a very small amount so that the water saturation of the specimen is made more rapid and dense.

The method for testing a hardly water-permeable soil material according to claim 1 is a first step in which a test piece of a hardly water-permeable soil material loaded in a test container is installed in a test device, wherein water in the test sample is removed by evaporation. 2 step, a third step of Genchijimi the air layer in the specimen by vacuum after the second step, a fourth step of infiltrating water into specimens by injecting high pressure water from the injection pipe, as appropriate to the test device Since it comprises the 5th process which performs a predetermined characteristic test after connecting the measuring instrument, the moisture layer in the specimen of the hardly water-permeable soil material is removed by evaporation, and then the air layer in the specimen is reduced. The sample is saturated with water by injecting high-pressure water into the sample and allowing water to penetrate into the sample, and the sample is quickly and densely saturated with water. There is an effect that can be made possible.

  The test method for a hardly water-permeable soil material according to claim 2 is the test method according to claim 1, wherein the second step is to move the test apparatus to a high-temperature drying furnace and heat the sample while heating at high temperature. Since it is characterized by evaporating and removing the moisture in the inside, in addition to the above-described effects, the effect of further rapidly and high-density moisture saturation of the specimen is achieved.

  The test method of the hardly water-permeable soil material according to claim 3 is the test method according to claim 1, wherein the second step is to evaporate water in the specimen by vacuuming the test device. In addition to the above-described effects, it has the effect that the moisture saturation of the specimen can be further rapidly and densely formed.

The test method of the hardly water-permeable soil material according to claim 4 is the test method according to any one of claims 1 to 3, wherein the third step is a step of supplying water-soluble gas from the injection pipe to the test apparatus. injected, since then have characterized and Turkey to leave only water-soluble gas lean trace by vacuuming, in addition to the above effects, filled with a water-soluble gas to the air layer formed by reduction in the flame Only a small amount of water-soluble gas remains in the specimen of the water-permeable soil material, so that the moisture saturation of the specimen can be increased more quickly and densely.

The method of testing low permeability soil material according to claim 5, in the test method according to any one of claims 1 to 3, after the third step, filling the water-soluble gas, after its In addition to the above effects, the method further includes the step of removing the air from the specimen by evacuation to leave only a small amount of water-soluble gas. Only a characteristic gas is allowed to remain in a very small amount so that the moisture saturation of the specimen can be further rapidly and densely produced.

The method for testing a hardly water-permeable soil material according to the present invention includes a first step of installing a test piece of a hardly water-permeable soil material loaded in a test container in a test device, a second step of evaporating and removing moisture in the test sample, third step, a fourth step of infiltrating water into specimens by injecting high pressure water from the injection pipe to Genchijimi the air layer in the specimen by vacuum after the second step, an appropriate measurement instrument to the test device It comprises the 5th process of performing a predetermined characteristic test after connecting.
Hereinafter, embodiments relating to a test method for a hardly water-permeable soil material according to the present invention will be described in detail with reference to the drawings. In this embodiment, diffusion characteristics and water permeability properties performed on a hardly water-permeable soil material. Among various characteristic tests such as air permeability characteristics and mechanical characteristics, it is intended to be a specimen of a hardly water permeable soil material used for the water permeability characteristics test.

FIG. 1 shows a step of drying a specimen for a water permeability test. The step (a) of filling a specimen for a water-impervious soil material into a container for a water permeability test and the step (b) of drying the specimen. Show.
In the figure, reference numeral 1 denotes a specimen of a hardly water-permeable soil material filled in a water permeability test container 2, which is a mixture of a material containing smectite such as commercially available bentonite and aggregates, clay, or the like. It consists of a low-permeability soil material with a low hydraulic conductivity and water and air impregnated inside.

  Therefore, in the poorly permeable soil material, in the region where there is a lot of water in the gaps between the clay particles, the clay particles that have swelled and swollen expand to make the gaps small and difficult to pass through the water. In the interstitial region that is not distributed, the clay particles remain dry, so that air permeates well, but water is obstructed by the air phase and difficult to pass. Furthermore, although air bubbles remain in the pore water, the actual condition is that even if water passes, the bubbles are not easily eliminated.

  Further, in this embodiment, when the sample is collected in an unsaturated state that is not dried or saturated, it is immediately loaded into the water permeation test container 2 so as not to be separated. The destruction of the specimen is prevented. However, if the state of the specimen is good, the specimen does not break even if it is not loaded in the water permeability test container 2, so that the water permeability test container 2 does not necessarily need to be filled. The handling which dries only 1 is also possible.

  In addition, since it is common to adjust the soil material to a water content ratio that is easy to roll or press-mold, the degree of saturation after construction exhibits about 70 to 90%. Is in an unsaturated state.

In the step of FIG. 1 (b) for drying the specimen, the water permeability test container 2 is placed in the drying furnace 3 and, for example, placed in a drying furnace at 110 ° C. for 24 hours to be completely dried. By releasing all the water in the form of water vapor, the water remaining in the gap between the specimens 1 is reduced to zero, and the air layer in the specimens is reduced to make the specimen 1 faint.
2-4 is embodiment which shows the pre-processing process in the test method of a hardly water-permeable soil material.

FIG. 2 shows a process of installing a water permeability test container filled with a dried specimen as it is in a test apparatus.
The test device 4 is composed of an upper and lower lid plate on which a water permeability test container can be installed, a water injection system device, a discharge system device, and a measuring instrument. 'Worn between. As will be described later, a vacuum pump (not shown) is connected to each of the upper and lower cover plates 5 and 5 ′ of the test apparatus 4 via hollow pipes 6 and 6 and open / close valves 7 and 7 ′ and 7 ′ and 7 ′. In each intermediate part of the hollow pipe 6, a water storage tank 8 for storing deaerated water in advance is closed via the opening / closing valves 9, 10, and the water storage tank 11 is closed via the opening / closing valves 9 ′, 10 ′. Linked in state.

FIG. 3 shows a process of pushing air into the atmosphere by introducing a water-soluble gas into the specimen by switching the open / close valve in the test apparatus.
In the step of introducing the water-soluble gas into the specimen of FIG. 3A, the hollow pipes 6 and 6 are in an open state without switching the on-off valves 7 and 7 ′. Then, the storage tanks 8 and 11 are disconnected by closing the open / close valves 9 and 10 of the water storage tank 8 storing the degassed water and the open / close valves 9 'and 10' of the discharge water storage tank 11. ing.

  In this state, a minute amount of air remaining in the specimen 1 is pushed out into the atmosphere by injecting a water-soluble gas into the specimen 1 from one hollow pipe 6. However, before the water-soluble gas is injected into the specimen 1, the air remaining in the specimen 1 is removed from both the hollow pipes 6 and 6 so that the water-soluble gas can be easily injected into the specimen 1. At the same time, it sufficiently penetrates into the air layer of the specimen 1.

  Next, in FIG. 3B, a vacuum pump is connected to both the hollow pipes 6 and 6, and the water-soluble gas filled in the specimen 1 is evacuated, and the inside of the specimen 1 is Only a small amount of water-soluble gas in a dilute state close to vacuum is included. Accordingly, the water-soluble gas from the specimen 1 can be evacuated from either one of the hollow pipes 6 or from both the hollow pipes 6 and 6.

FIG. 4 showing the next step shows an outline for introducing deaerated water into the specimen 1 by switching the open / close valve in the test apparatus.
In this step, the injection-side hollow pipe 6 to which the vacuum pump is connected is closed by switching the opening / closing valve 7 ′, and the opening / closing valves 9, 10 of the water storage tank 8 storing degassed water. And the open / close valves 9 ′ and 10 ′ of the discharge-side water storage tank 11 and the open / close valve 7 of the discharge-side hollow pipe 6 are switched to the open state so that the water storage tanks 8 and 11 and the specimen 1 are in a water-flowing state. Is forming.

  Next, the injection pressure control gas injected into the water storage tanks 8 and 11 instantaneously infiltrates the degassed pressure water into the specimen 1, but the hollow pipe 6 of the water injection system device and the discharge system device. , 6 is temporarily released from the water absorption swelling state of the specimen constituting particles by the above-mentioned process, and the gap between the particles is formed in a vacuum state, so that it is stored in the water storage tanks 8 and 11. The deaerated water penetrates without difficulty from the upper and lower end surfaces of the specimen 1 to the inside of the specimen 1 and forms a saturated state in the specimen 1 easily and reliably.

  The injection of degassed pressure water into the specimen 1 is not necessarily carried out from the water storage tanks 8 and 11 as in the present embodiment, but from either one of the water storage tanks 8 and 11. May be injected.

FIG. 5 shows, as a microscopic simulation diagram, the transformation state of the specimen that changes in each of the above steps.
Fig.5 (a) has shown the test piece of the state extract | collected at the construction site.
The water content of the specimen is adjusted to conditions that facilitate rolling or press molding, and the degree of saturation immediately after construction exhibits 70 to 90%. That is, the clay particles 12 are in a state where the water-absorbing and expanding particles and the dry clay particles are mixed, and the remaining region is composed of water 13 and air 14.

  In the specimen 1 where the water is present in the gaps between the clay particles in the hardly permeable soil material, the water-swelled clay particles 12 expand to make the gaps difficult to pass through. In the gap region where water is not sufficiently distributed, since the clay particles 12 remain dry, the air 14 permeates well, but the water is obstructed by the air phase and is difficult to pass.

FIG. 5B shows a transformed state formed in the specimen after being dried.
Since the specimen 1 evaporates the moisture 13 contained in the gaps between the clay particles 12 in the hardly water-permeable soil material and the moisture that swelled the clay particles 12 and removes most of them to the outside, it is difficult. The water-permeable soil material is composed of clay particles 12 and an air layer 14 in a contracted state.

  FIG. 5 (c) shows that the specimen 1 in the water permeability test container 2 is replaced with air 14 and a small amount of carbon dioxide 15 by supplying and evacuating carbon dioxide 4 which is a water-soluble gas. The specimen 1 at this stage is composed of particles 12 and a small amount of carbon dioxide 15.

  FIG. 5 (d) shows a saturated state of the specimen when the deaerated water is instantaneously injected into the specimen 1 in the water permeability test container 2, and the specimen 1 is shifted to the final stage for a while. It is saturated.

  Since it is not instantaneous that soil materials such as bentonite make water permeability remarkably minute by the water absorption swelling action, degassed water injected instantaneously at a high pressure of about 0.1 to 1.0 MPa was injected. Spread water evenly throughout the specimen. Therefore, the specimen 1 is composed of clay particles 12, water 13 having a predetermined water content ratio, and a small amount of carbon dioxide gas 15.

  And in the micro area | region of a test body, water cannot permeate | transmit and a space | gap without a water | moisture content generate | occur | produces as shown in the figure. However, since the high-pressure water injection is continued from the instantaneous state, the carbon dioxide gas 15 is dissolved in the water, so that all the gaps in the specimen are finally filled with water. Become.

  As described above, the poorly water-permeable soil material, which is generally in a half-water-containing state, remains in a state where it cannot be replaced by water because the air phase remains in the gap region filled with water. For this reason, it is clarified that this test method was able to solve the problem that it was difficult to saturate as a specimen even when water was injected as in the conventional method.

  That is, first, the water-impermeable soil material that is halfway in the water-containing state is formed into a state in which there is no water by high-temperature drying or vacuum drying at room temperature, and the water absorption swelling state of the specimen constituent particles is temporarily released. Thereafter, carbon dioxide gas is injected to eliminate the air phase, and then evacuation is performed to form a dilute carbon dioxide gas state in which no air is present in the gaps of the hardly water-permeable soil material. The sample 14 has a very low possibility of air remaining, and even if it remains, such an extremely small amount of air 14 flows into the test sample 1. This is because it cannot be an amount that would hinder the trend of the future.

  Therefore, when high pressure water is poured into a poorly permeable soil material without an air layer, the water instantly spreads all over the specimen, and water, water vapor, and a small amount of carbonic acid are placed in the gaps between the clay particles. Since only gas exists, carbon dioxide gas is water-soluble, so it dissolves in the water in the gap for a while and becomes zero in volume. Therefore, this test method can produce a desired specimen made of a hardly water-permeable soil material in which the gap is saturated with water.

  The test method for the above hardly water-permeable soil material is that the sample of the hardly water-permeable soil material is heated at a high temperature to evaporate and remove the moisture in the sample, and then evacuated in the installed test apparatus. The air layer is reduced, and then water is infiltrated into the specimen by injecting high-pressure water to saturate the specimen, and moisture saturation of the specimen is completed quickly and densely. This makes it possible to conduct characteristic tests smoothly.

  In the following, an embodiment relating to a test method for a hardly water-permeable soil material according to the present invention will be described in detail with reference to the drawings. The same reference numerals are used for the same parts as the test method described above to facilitate understanding. This is not shown for redundant explanations.

  FIG. 6 shows a step of drying a specimen for a water permeability test. The step (a) of installing the specimen loaded in the container for the water permeability test in the test apparatus and the specimen in a state of being installed in the test apparatus are dried. Step (b) is shown.

  In the test method described above, high-temperature drying is performed in the state of the water permeability test container 2 filled with the specimen 1, but in the present embodiment, the test apparatus 4 of the water permeability test container 2 filled with the specimen 1 is preliminarily provided. It is installed.

In the step of FIG. 6B for drying the specimen, the test apparatus 4 in which the water-permeable test container 2 filled with the specimen 1 is installed in advance is placed in the drying furnace 3, for example, a drying furnace at 110 ° C. For 24 hours or more to dry completely. As a result, all the water contained in the specimen is released, so that the water remaining in the gap of the specimen 1 becomes zero and the specimen 1 is in a faint state.
In addition, as a means for releasing moisture contained in the specimen, in addition to completely drying with a drying furnace as described above, the moisture in the specimen is vacuum evaporated by evacuating the test apparatus 4. It is also possible to remove it.

Thus, the specimen 1 to be dried in the present embodiment is in a faint state in which a slight amount of water vapor and a small amount of water-soluble gas remain in the internal gaps. Since 2 is installed in the test apparatus 4 in advance, the specimen does not collapse and disperse even if it is taken out from the drying furnace 3 and moved for the next test stage.
Further, if the hollow pipe 6 is closed immediately before taking out from the drying furnace, the specimen can be filled with only water vapor and the air can be made lean.

  The subsequent processing steps for the specimen 1 are the same as in the case of the above test method. In addition, the change state of the specimen that changes in each step is also changing. Omitted.

  The subsequent steps in each test method such as diffusion characteristics, water permeability characteristics, air permeability characteristics and mechanical characteristics performed using the hardly water-permeable soil material according to the present invention are the same as those already proposed by the inventors. However, the test method performed using the specimen of the hardly water-permeable soil material pretreated as described above will be described below.

FIG. 7 is a schematic diagram showing an embodiment for accurately measuring an extremely small amount of water permeation in a test process in the test method for a hardly water-permeable soil material of the present invention.
In the method for testing a hardly water-permeable soil material according to the present invention, a water-permeable test container filled with a dry specimen is directly attached to the test apparatus, so that the specimen and the water-permeable material can be used in the process leading to saturation of the specimen. It is possible to eliminate the intrusion of air between the test container and the test container, which contributes to the improvement of test accuracy.

  Therefore, in the embodiment shown in FIG. 7, the water permeability test container 2 used when the specimen 1 is prepared as the container used for the water permeability test in the test apparatus 4 is used as it is, and the water permeability test container 2 is tested. The device 4 is mounted between the upper and lower cover plates 5 and 5 ′.

  A vacuum pump (not shown) is connected to each of the upper and lower cover plates 5, 5 ′ of the test apparatus 4 through hollow pipes 6, 6 and open / close valves 7, 7, 7 ′, 7 ′. The intermediate portions 6 and 6 are connected via the open / close valves 9 and 10 of the water storage tank 8 storing the deaerated water and the open / close valves 9 ′ and 10 ′ of the water storage tank 11 in advance.

  As described above, the method for testing a hardly water-permeable soil material according to the present invention is configured so that the time required for the saturation process can be almost zero without requiring a long time as in the prior art, and the water permeability test can be started immediately. It can be done.

  As shown in FIG. 7, the measurement in the present embodiment is performed by injecting degassed water from the water storage tank 8 into the specimen 1 by press-fitting a constant water injection pressure control gas into the water tank 8. After the degassed water discharged from the discharge water storage tank 11 is received, the discharged water pushed out from the transparent tube 16 having a small inner diameter of about 2 mm connected to the outlet side of the water storage tank 11, This is done by measuring the moving speed of the meniscus indicated by the discharged water.

  The amount of water measured in the test is about 0.0346 ml / day as in the above-described calculation example, or about 1/10 of this flow rate, so ultra-trace measurement must also be considered. However, even if a tube having an inner diameter of 2 mm is employed as in the present embodiment, the water permeation amount corresponding to the moving amount of the meniscus is 10 mm / day is 0.1 × 0.1 × 3.14 × 1 = 0. Since it is 03 ml / day, sufficient resolution can be exhibited.

  In the test of the hardly permeable soil material, the permeability coefficient is measured by measuring the permeability rate (ml / s) from the movement speed of the meniscus of the discharged water. Can be directly connected to the open / close valve 7 of the hollow pipe 6 or the upper lid 5 of the test apparatus 4 instead of the outlet side of the discharge-side water storage tank 11.

  Furthermore, the measurement is performed by connecting a water bag (not shown) to the tip of the small inner diameter tube 16 and using a commercially available weighing scale having a resolution of 0.001 g, thereby increasing the weight of the trace water stored in the water bag. It is possible to measure the water permeation rate (ml / s) by measuring once per day.

  The graph of FIG. 8 has time (seconds) on the horizontal axis and cumulative water permeability (ml) on the vertical axis, and is a specimen of 50 mmФ × 20 mmH under the condition of a water injection pressure of 0.4 MPa, which is configured according to the present invention. Is a measured value obtained by plotting a value obtained by measuring the water permeation amount from the meniscus movement amount on the drain side in FIG.

  As shown in the figure, although the water permeability cannot be confirmed in the first two days, the value that can be sufficiently observed from the third day is clarified. Incidentally, the hydraulic conductivity calculated from the hydraulic conductivity value of the second day to the seventh day is 4.3E-13 m / s, and the long-term hydraulic conductivity from the 17th day to the 31st day is 2.0E-13 m. / S.

  As described above, since the test method for hardly permeable soil material according to the present invention is configured as in the embodiment, the specimen of the hardly permeable soil material is heated to a high temperature to evaporate moisture in the specimen. The sample is then saturated with water by injecting high-pressure water into the air layer in the sample that has been removed, and then allowing the sample to penetrate the water, thereby quickly and densely saturating the sample. It is possible to smoothly perform the characteristic test thereafter.

  As described above, the present invention has been described in detail on the basis of the embodiment. However, the test method of the hardly water-permeable soil material according to the present invention is not limited to the above embodiment, and the hardly water-permeable soil material is used. It is possible to deal with each characteristic test such as diffusion characteristic, air permeability characteristic and mechanical characteristic to be carried out in the same way, and concretely regarding test container, water injection system apparatus, discharge system apparatus and measuring instrument etc. It goes without saying that other modifications can be made in various ways without departing from the spirit of the present invention.

  The present invention is used for burying and disposing of industrial waste or radioactive waste, and has a very low permeability to bentonite-based hardly permeable soil material including clay material having water absorption and expansion properties. It can be applied as a test method for poorly water-permeable soil materials that can simply and quickly confirm each property test such as properties and mechanical properties.

Embodiment showing a step of filling a specimen for water permeability test and drying in a test method for hardly water permeable soil material In the test method for poorly permeable soil material of the present invention, a process diagram for installing a water permeability test container in a test apparatus in which a water injection system apparatus, a discharge system apparatus and a measuring instrument are arranged. Process diagram for filling a specimen with water-soluble gas, removing residual air, and evacuating to fill with a small amount of water-soluble gas Process diagram for instantaneously injecting deaerated water into the specimen to bring the specimen into water saturation Microscopic simulation diagram showing the state of transformation of the specimen that changes in each process In the method for testing a hardly water-permeable soil material of the present invention, an embodiment showing a step of drying by installing a container for water permeability test of a specimen in a test apparatus. The schematic diagram which shows the state which arrange | positions the test body in the saturation state of predetermined moisture content by the test method of the hardly water-permeable soil material of this invention Water permeability actual measurement data obtained by the test method for poorly permeable soil material in the present invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Specimen, 2 Permeability test container, 3 Drying furnace, 4 Test apparatus, 5, 5 'Upper / lower cover plate, 6 Hollow pipe, 7, 7' Open / close valve, 8 Water storage tank, 9, 9 ', 10, 10' Open / close valve, 9 Permeability test container, 11 Water storage tank, 12 Clay particles, 13 Water, 14 Air, 15 Carbon dioxide gas, 16 Tube.

Claims (5)

The first step in which the specimen of the hardly permeable soil material loaded in the test container is installed in the test apparatus, the second step in which water in the specimen is evaporated and removed , and the air in the specimen by vacuuming after the second step the third step of Genchijimi layer, a fourth step of infiltrating water into specimens by injecting high pressure water from the injection pipe, a fifth step of performing a predetermined characteristic test after connecting an appropriate measurement instrument to the test device Test method for poorly water-permeable soil materials composed of   2. The method for testing a hardly water-permeable soil material according to claim 1, wherein the second step moves the test apparatus to a high-temperature drying furnace and evaporates and removes moisture in the specimen while heating at a high temperature.   2. The method for testing a hardly water-permeable soil material according to claim 1, wherein in the second step, the moisture in the specimen is vacuum evaporated by evacuating the test apparatus. Third step, by injecting a water-soluble gas from the injection tube to the test apparatus, then the preceding claims 1, wherein the benzalkonium allowed to remain only soluble gas lean trace by evacuating the The method for testing a hardly water-permeable soil material according to any one of the above. After the third step, according to claim 1, filled with a water-soluble gas, wherein the vacuum to from in the specimen further comprises the step of leaving only a water-soluble gas lean traces by removing the air after its The method for testing a hardly water-permeable soil material according to any one of claims 1 to 3 .

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