JP5181295B2 - Rolling method for clay-based soil materials - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a rolling compaction method for clay-based soil materials, and, for example, relates to a compacting method for clay-based soil materials that constitute a low water-permeable layer in a low-level radioactive waste embedding disposal facility. .

  A low-level radioactive waste embedding disposal facility 100 is planned as a mine facility having a cross-sectional structure as shown in FIG. 13, for example. The buried disposal facility 100 has a structure in which a backfill material 101 and a low water permeable layer 102 are laid in an excavated underground mine, and a radioactive waste container 103 and its surroundings are filled with a mortar 104 to be buried. It has become. A layer having excellent water shielding performance is constructed by rolling the bentonite clay material on the low water permeability layer disposed on the outer peripheral portion of the radioactive waste container (see, for example, Patent Document 1). .

In addition, in a low-level radioactive waste burial facility, a density of 1.6 Mg / m ³ or more capable of providing poor permeability (permeability coefficient of less than 1E-12 m / s) is required as the performance of the low permeability layer. In addition, it is necessary to suppress that the water absorption swelling pressure of the low water permeable layer due to unnecessarily high density adversely affects the radioactive waste storage housing accommodated therein. For example, there is a relationship between effective bentonite dry density and hydraulic conductivity as shown in FIG. 14 (see, for example, Non-Patent Document 1), and a relationship between bentonite density and swelling pressure as shown in FIG. 15 (see, for example, Non-Patent Document 1). Therefore, it is desired that the bentonite-based clay material be pressed by a density distribution that has a dry density as close to 1.6 Mg / m ³ as possible and does not vary as much as possible.

On the other hand, the low water-permeable layer described above is required to be compacted to about 1.6 Mg / m ³ with a value obtained by converting bentonite into a dry density with a thickness of 1 m, for example. As a rolling method for bentonite clay material having such a performance, the applicant of the present application has proposed a rolling method using a multi-running rammer device as shown in Patent Documents 2 and 3.

JP 2004-12356 A JP 2008-38338 A JP 2008-49312 A

Munehiro Maeda, Kenji Tanai et al., Basic Properties of Calcium-type and Calcium-type Bentonite ─Swelling pressure, hydraulic conductivity, uniaxial compressive strength and elastic modulus─, Power Reactor and Nuclear Fuel Development Corporation, PNC TN841098-021, 1998

However, in the techniques shown in Patent Documents 2 and 3, the dry density is in the range of 1.6 to 1.8 Mg / m ³ , and the dry density is not uniform.

  This invention is made | formed in view of the above, Comprising: It aims at providing the compaction method of the clay-type soil material which can make variation in dry density small and can make dry density uniform.

To solve the above problems and achieve the object, the present invention provides a compaction method of constructing clay soil material pressure rolling the clay soil material with self-propelled Tarenso rammer device, the self-propelled In a cylindrical container in which a circular rolling plate having the same area as one rolling plate of a multi-running lammer device can be drawn out, the clay-based soil material to be constructed is sprinkled with a thickness to be constructed, and the rammer that delivers the one rolling plate and the above-mentioned By performing a rolling test using a circular rolling plate with different rolling time and feeding height, the density after rolling in each condition is measured, and the feeding height of the hammer that allows the hammer to efficiently compact and The traveling speed of the traveling multi-runner device is derived, the feeding height of the runner is derived, and the self-running multi-runner device is derived on the rolling end surface where the rolling is completed. Multi-running rammers By running at a constant rate over a speed kept constant at feeding height rammer which derive feeding height of rammer for construction surface, characterized in that the pressure gradually rolling at a constant speed.

  Moreover, the present invention is characterized in that, in the above-mentioned method for rolling compaction of clay-based soil material, the clay-based soil material is divided into a plurality of times and compacted to a desired density.

  Further, according to the present invention, in the above-mentioned method for rolling compaction of clay-based soil material, a clay-based soil material having a moisture content adjusted so that the saturation degree when it is compacted to the target density is 85% to 90%. It is characterized by taking out and rolling.

  The method for rolling compaction of clay-based soil material according to the present invention is such that a self-propelled multi-equipped runner device is driven at a constant speed on the rolling completion surface after rolling, so that the feeding amount of the runner for the construction surface to be constructed from now on. Since the thickness is made constant and the rolling is gradually performed at a constant speed, it can be compacted with a uniform density.

  Moreover, since the feeding height of the rammer relative to the construction surface is set to a height at which the rammer can be compacted efficiently, the clay-based soil material can be efficiently compacted.

  In addition, as the rolling progresses, the construction surface becomes lower in the middle of rolling, and the feeding height of the rammer becomes higher, but the clay-based soil material is divided into several times and compacted to the desired density, so it must be significantly higher. It can be compacted with a uniform density.

  In addition, as the rolling time increases, the density gradually increases and the degree of saturation also increases. And when rolling pressure advances and it becomes the water content ratio which becomes 85%-90% of saturation, saturation will not advance any more. In other words, by adjusting the water content ratio so that the degree of saturation when the clay-based soil material rolled out on the construction surface is compacted to the target density is 85% to 90%, the uniform density close to the target density can be obtained. Rolling work can be performed.

  By performing a rolling test by changing the rolling time and feeding height, using a rammer that feeds out one rolling plate of a self-propelled multi-runner device and a circular rolling plate having the same area as the one rolling plate, If the density after rolling in each condition is measured, it is possible to derive the running height of the runner relative to the construction surface and the traveling speed of the multi-runner runner device.

FIG. 1 is a conceptual diagram showing a compaction test using a single rammer having a circular rolling plate having the same area as one rolling plate. FIG. 2 is a diagram showing the result of the compaction test when the reaction force is free. FIG. 3 is a diagram showing a result of a compaction test in a case where reaction force is not released. FIG. 4 is a diagram showing the relationship between the rolling stroke of the runner and the dry density in the compaction test, and shows the result when the rolling time is 5 seconds. FIG. 5 is a diagram showing a relationship between the rolling pressure stroke of the runner and the dry density in the compaction test, and shows the result when the rolling time is 10 seconds. FIG. 6 is a diagram showing an example in which the construction surface becomes low during the rolling and the rolling stroke of the rammer is not optimal. FIG. 7 is a diagram illustrating an example in which the rolling pressure stroke of the rammer is adjusted and the rolling pressure stroke of the rammer is optimized when the construction surface becomes low during the rolling. FIG. 8 is a diagram showing the test results in the compaction test, and is a diagram showing the relationship between the rolling time and the dry density. It is the figure which arranged the test result shown in FIG. 8 in the relationship between rolling pressure time and saturation. FIG. 10 is a diagram showing a rolling compaction method using a multi-running rammers device. FIG. 11 is a diagram showing a test result of a compaction test using a multi-running rammers device. FIG. 12 is a diagram showing the density distribution obtained by dividing each layer compacted by the multi-running rammers into upper, middle and lower parts. FIG. 13 is a cross-sectional view showing a tunnel facility in a low-level radioactive waste burying and disposal facility. FIG. 14 is a diagram showing the relationship between the drying density of bentonite and the water permeability. FIG. 15 is a diagram showing the relationship between the drying density of bentonite and the swelling pressure.

  Hereinafter, an embodiment of a rolling compaction method for clay-based soil material according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  The clay-based soil material rolling method according to the present embodiment is for constructing a low-permeability layer in a low-level radioactive waste burying disposal facility, and is a self-propelled multi-runner device 3 (Fig. 10) to reduce the variation in dry density in the rolling compaction method for clay-based soil materials, and to determine in advance the compaction conditions that match the target dry density by small-scale element tests as shown in FIG. The purpose is to be able to.

  First, a compaction test using one rammer 2 will be described with reference to FIG. Factors noted as rolling conditions are rolling time and moisture content of bentonite material.

  The material used for the compaction test of one Ramma 2 is bentonite 10 mm under (trade name: Kunigel GX, manufactured and sold by Kunimine Industries Co., Ltd.), with a moisture content ranging from 20% to 25% in 5 levels. What was adjusted to was used. One rammer 2 used was a pneumatically driven unit (trade name: Sandranma) used in the self-propelled multi-runner device 3. In addition, as shown in FIG. 1, the test method is as follows. A bentonite material B having a predetermined moisture content is put into a test mold 1 having a diameter of 150 mm and a height of 200 mm, and rolled by a single rammer 2 for 5 to 45 seconds. And measuring the dry density. The finished thickness by one rolling is 50 mm, and one sample is prepared for the test mold 1 by four rollings.

  In addition, in addition to the two factors of bentonite material moisture content and rolling time, the test also focused on the fixing conditions of the luma and the rolling stroke (feeding height) of the rammer.

  First, the head of Ranma 2 was grasped by hand, the reaction force of the head was made free, and the pressure was continuously rolled until a predetermined rolling time was reached. For this reason, the distance between the circular rolling plate 21 and the bentonite material B is not constant. The test results are shown in FIG. The horizontal axis is the rolling time, and the vertical axis is the dry density. From this figure, it can be seen that as the moisture content increases, it becomes difficult to compact, but the dry density does not change.

In addition, as shown in FIG. 2, when the water content ratio of the bentonite material is 22.2%, 23.2%, the dry density is 1.6 ( Mg / m ³ ), and even if the rolling time is longer than this, no increase in density is observed. That is, since the density variation accompanying the change in the rolling pressure energy is reduced, it is suggested that a low water permeability layer with little variation can be constructed by devising the water content ratio.

Next, the head of Ramma 2 was fixed so as not to release the reaction force. Specifically, after fixing the height position of the ramp 2 and continuing the rolling for 5 seconds, the rolling stroke of the ramp 2 (the distance from the bottom surface of the circular rolling plate 21 to the bentonite material) is 100 mm each time. Thus, while adjusting the height position of the runner 2, the rolling pressure was repeated for 5 seconds until the predetermined cumulative time was reached. In this case, since the fluctuation of the rolling stroke of the rammer 2 can be reduced, rolling energy with little variation can be given to the bentonite material B. Moreover, when the height position of the rammer 2 is fixed, it is considered that a large rolling energy can be applied to the bentonite material B due to the reaction force effect. The test results are shown in FIG. The horizontal axis is the total rolling time, and the vertical axis is the dry density. From this figure, it can be seen that when the height position of the luma 2 is fixed, it can be compacted to a dry density of 1.6 Mg / m ^{3 by} rolling for 10 seconds. Further, from this figure, it is confirmed that when the water content ratio of the bentonite material is 23% and 23.6%, it does not deviate from the target density even if the rolling pressure time is doubled.

  Next, a compaction test was performed by changing the rolling stroke of the runner 2, and a suitable rolling stroke was derived. The test results shown in FIG. 4 are those in which the rolling time is 5 seconds, and the test results shown in FIG. 5 are those in which the rolling time is 10 seconds. In these drawings, it is clearly shown that the rolling energy of the rammer 2 varies depending on the rolling stroke of the rammer 2 and, as a result, the dry density varies. It can also be seen that the runner 2 used in the test is efficient when the rolling stroke is 13 cm.

  By the way, if the head of the luma 2 is fixed so as not to release the reaction force, it is initially fed out with an optimum rolling stroke (for example, 13 cm), but when the compaction of the bentonite material B proceeds, it is shown in FIG. Thus, the construction surface of the bentonite material B becomes low in the middle of rolling, and the optimum rolling stroke is lost. And the appropriate rolling energy cannot be given to the bentonite material B.

  Therefore, as shown in FIG. 7, if the bentonite material B is compacted in a plurality of times and the rolling stroke is adjusted each time, the fluctuation of the rolling stroke of the rammer 2 can be reduced. . Therefore, appropriate energy is given to the bentonite material B.

Next, a compaction test was performed by changing the water content ratio of the bentonite material B, and the relationship between the rolling time and the dry density was determined for each water content ratio of the bentonite material B. The test results are shown in FIG. FIG. 9 shows a summary of the test results focusing on the degree of saturation obtained from the dry density and the water content ratio. The horizontal axis is the rolling time, and the vertical axis is the saturation. From these figures, it can be seen that as the rolling time increases, the rolling energy increases and the drying density and saturation increase. It can also be seen that when the rolling pressure advances and the saturation level is 85% to 90%, the saturation level is less likely to increase. In other words, if the clay-based soil material whose water content ratio is adjusted is rolled out and subjected to rolling so that the saturation when compacted to the target density is 85% to 90%, the rolling energy is reduced. Even if there is some variation, it is difficult to be affected by it, and it can be rolled at a uniform density close to the target density. In the embodiment of the present invention, the moisture content of the clay-based soil material having a saturation degree of 85% to 90% when compacted to the target density is 18.5%, and according to this, If the soil material is wet, the dry density will not vary even if the compaction energy varies somewhat.

  Based on the above, when the bentonite-based soil material B is rolled using the self-propelled multiple-running rammers 3, as shown in FIG. By making the traveling multi-equipment runner device 3 run at a constant speed, the feeding height of the runner 2 with respect to the construction surface to be constructed is made constant, and the rolling is gradually rolled at a constant speed.

  Further, the feeding height of the rammer 2 relative to the construction surface is set to 13 cm from the test result described above, that is, the height at which the rammer 2 is efficiently compacted. In addition, it is preferable that the compacting operation is compacted into a plurality of times, for example, three times or four times, and is compacted to a desired density. The rolling type multi-equipment runner device 3 is rolled and applied while running at a constant speed.

  Furthermore, the bentonite-based soil material B with the moisture content adjusted is rolled out and subjected to rolling so that the degree of saturation when it is compacted to the target density is 85% to 90%. By performing such rolling operation in a plurality of times, fluctuations in the rolling stroke of the runner 3 can be reduced, and the feed height of the runner 2 in the self-propelled runner device 3 can be finely adjusted. It becomes unnecessary and management at the time of construction becomes easy.

  In this way, after the bentonite-based soil material B with the moisture content adjusted so that the saturation when the compaction is compacted to the target density is 85% to 90%, the runner height is set to a feeding height that can be compacted efficiently. The self-propelled multi-equipped runner device 3 with the feed height of 2 adjusted in advance runs at a constant speed on the rolling end surface where the rolling is completed so that the required rolling time is divided by the number of rolling times. However, if the rolling compaction is applied, the dry density of the bentonite-based soil material B obtained as a result of the rolling compaction by the multi-running rammers becomes very homogeneous as shown in FIG.

As described above, the bentonite-based soil material B actually rolled by the self-propelled multi-runner device 3 shown in FIG. 10 is cored, and the average dry density of each layer of the rolling is plotted in FIG. is there. Further, among these collected samples, the sample collected from the No. 2 hole was divided into three parts, upper, middle, and lower, and a more detailed distribution of dry density was measured. The results are shown in FIG. 12, and it can be seen that the upper part of each pressed layer has a higher density and the lower part has a lower density. It is also true that it does not exceed 95%. As a result, the average dry density of each rolled layer exhibits a value close to the target 1.6 Mg / m ^3, and the average saturation of each layer is in the range of 85 to 90%.

  In other words, if the rolling condition is determined by the above-described element test, the rolling condition becomes the rolling condition of the self-propelled multi-runner device 3 as it is. That is, the clay-based soil material to be constructed is sprinkled to the construction work thickness in a cylindrical container in which the circular rolling plate 21 having the same area as that of one rolling plate of the self-propelled multi-runner device 3 can be fed. By measuring the density after rolling in each condition by changing the rolling time and feeding height using the rammer 2 and the circular rolling plate 21 for feeding the pressure plate, the optimum rolling conditions are determined. If it is determined, the feed height of the runner 2 of the self-propelled multi-runner device 3 and the traveling speed of the self-runner multi-runner device 3 can be set.

DESCRIPTION OF SYMBOLS 1 Test mold 2 Rama 21 Circular compaction board 3 Self-propelled multi-equipment Ranma equipment B Bentonite material

Claims (3)

In the rolling compaction construction method for clay-based soil materials, which rolls clay-based soil materials using a self-propelled multi-running ramma device ,
In a cylindrical container in which a circular rolling plate having the same area as one rolling plate of the self-propelled multi-runner device can be drawn out, the clay-based soil material to be constructed is sprinkled with the planned construction thickness, and the one rolling plate is disposed. Performing the rolling test by changing the rolling time and the feeding height using the feeding roller and the circular rolling plate, measure the density after rolling in each condition, and feed the hammer that efficiently compacts the hammer. Deriving the height and the traveling speed of the self-propelled multi-runner device,
The running height of the runner is the same as the running height of the runner, and the self-propelled multi-runner device is derived from the self-propelled multi-runner device on the rolling end surface after rolling. A rolling compaction method for a clay-based soil material, characterized in that, by running, the feed height of the runner with respect to the construction surface is kept constant at the feed height of the runner, and rolling is performed gradually at a constant speed. The method for rolling and applying clay-based soil material according to claim 1, wherein the clay-based soil material is divided into a plurality of times and compacted to a desired density . 3. The clay-based soil material having a moisture content adjusted so as to have a saturation degree of 85% to 90% when compacted to a target density, and rolling and rolling. Rolling construction method for clay soil materials.

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