JP6101019B2 - Soil-based deformation following water-blocking material and method for producing the same - Google Patents

Description

  The present invention relates to a soil-based deformation-following water shielding material used as a water shielding work for a managed waste final disposal site provided on the sea surface, and a method for manufacturing the same.

  In addition to water imperviousness, construction work that can be handled reliably and easily at sea, long-term durability against deterioration and corrosion, external forces such as earthquakes, etc. Therefore, followability when deformation occurs, repairability when the imperviousness is damaged, and economic efficiency are required. As a material that satisfies such a requirement, there is a soil-based deformation follow-up water shielding material. Generally, soil-based deformation-following water-insulating materials are made of only inorganic materials with clay as the main material, so there is no water deterioration and no material deterioration, and no cement or other solidifying materials are blended. However, it has the feature that it can follow deformation without generating cracks or voids.

  As shown in FIG. 1, the soil-based deformation-following water-insulating material is used as a side water-impervious work and a bottom water-impervious work for a managed waste final disposal site. As shown in FIG. 1, the managed waste final disposal site 1 is constructed by surrounding the sea surface with a revetment 2. As the structure of the revetment 2, for example, a double steel (pipe) sheet pile revetment shown in FIG. 1 is adopted. The revetment 2 is constructed by placing H-shaped steel sheet piles 3 and steel pipe sheet piles 4 on the seabed ground to construct two rows of steel (pipe) sheet pile walls. It has a structure in which the filler 6 is inserted between the steel (pipe) sheet pile walls.

  When the upper layer of the seabed is the sandy soil layer 7 (permeable layer) and the lower layer is the viscous soil layer 8 (impermeable layer), the H-shaped steel sheet pile 3 Is penetrated to the viscous soil layer 8. Then, as a side water-impervious work, the joint compartment of the H-shaped steel sheet pile 3 is filled with a soil-based deformation follow-up water-insulating material D. In addition, based on the fail-safe design policy, as a side water-impervious work, a double water-blocking work is applied to the joint between the flanges of the H-shaped steel sheet pile 3 or a water-proof sheet is used in combination. Water structure is built. In response to the sandy soil layer 7 having high water permeability in the upper layer of the seabed ground, a soil-based deformation follow-up water shielding material D is laid on the sandy soil layer 7 as a bottom impermeable construction. Thus, an artificial impermeable base is constructed. And in order to protect a bottom surface impermeable construction, the covering sand 9 is constructed in the upper part of the soil system deformation followable water shielding material D.

Non-Patent Document 1 describes a standard regarding the water-blocking performance of the side-surface impermeable works and the bottom-surface impermeable works. As a standard of the side water-impervious construction, it is determined that the water-impermeable material has a thickness of 50 cm or more and a water permeability coefficient of 1 × 10 ⁻⁶ cm / s or less, or has a water shielding performance equivalent to or higher than this. Moreover, as a standard of the bottom impermeable construction, it is determined that the impermeable material has a thickness of 5 m or more and a permeability coefficient of 1 × 10 ⁻⁵ cm / s or less, or has a water shielding performance equal to or higher than this. . Therefore, the hydraulic conductivity (necessary hydraulic conductivity) that satisfies the above-mentioned criteria for the water-blocking performance is obtained by calculation for each thickness of the soil-based deformation-following water-blocking material D used as the side water-blocking work and the bottom water-blocking work. There is a need.

  As a soil-based deformation-following water-insulating material, a marine clay suspension is mixed with powdered bentonite (hereinafter, bentonite is referred to as powdered bentonite) as a gap adjusting material, which is a gel-like substance. A modified product is disclosed in Patent Document 1. Further, as a gelling agent for the soil-based deformation-following water shielding material disclosed in Patent Document 1, a silicate or the like (for example, water glass) is further mixed to increase the gel strength. Is disclosed. In addition, as a soil-based deformation-following water-insulating material that does not use marine clay, Patent Document 3 is a material obtained by mixing sand, bentonite, and fresh water and then mixing it with water glass to modify it into a gel-like substance. It is disclosed. Further, Patent Document 4 discloses a mixture of sand, highly swellable bentonite, and seawater.

Japanese Patent No. 3996915 Japanese Patent No. 3802777 Japanese Patent No. 4655875 JP 2008-43845 A

Edited by the Research Center for Advanced Port Space Environment, “Management Waste Landfill Revetment Design, Construction and Management Manual (Revised Version)”, August 2008

  The soil-based deformation-following water shielding material disclosed in Patent Documents 1 and 2 has an excellent advantage that dredged clay generated mainly in port construction can be effectively used as marine clay as a base material. Therefore, when there is dredging work in the vicinity, excellent cost merit can be obtained by diverting the dredged clay generated there as a base material of the soil-based deformation follow-up water shielding material. However, when there is no dredging work in the vicinity, it is necessary to dredge marine clay, and it is difficult to obtain cost merit when the number of soil-based deformation-following water shielding materials is small.

  In addition, for example, when constructing a managed waste final disposal site in an area where there is little marine clay, such as the Sea of Japan, it is necessary to transport marine clay dredged in a long distance, It becomes difficult to obtain cost merit. Furthermore, if the business operator who constructs the managed waste final disposal site is different from the business operator who conducts marine clay dredging, there is also the inconvenience that close coordination between the business operators is required. As described above, when applying the soil-based deformation-following water shielding material disclosed in Patent Documents 1 and 2, procurement of marine clay is a major issue.

  The water shielding performance of the soil-based deformation-following water shielding material can be adjusted by the amount of bentonite mixed with marine clay. As more bentonite is mixed with marine clay, the water shielding performance is improved (water permeability is reduced), but fluidity is lost and workability is lowered. The optimum mixing amount of bentonite with respect to marine clay is determined by blending design so as to have a water shielding performance that satisfies the standard and a fluidity that can be applied. Naturally, the optimum mixing amount of bentonite varies depending on the soil properties of the marine clay, so if the variation in soil properties of the marine clay used is large, the compounding design and construction management will be complicated. There are challenges.

  Moreover, since this soil system deformation | transformation followable water-impervious material consists of a mixture of marine clay and bentonite, it has the outstanding water-impervious performance by containing many clay components. On the other hand, it is characterized by high water content (large gap ratio) and large consolidation subsidence, as in soft-viscous land. Consolidation settlement leads to the advantage of further improving the water-insulating performance of the soil-based deformation-following water-blocking material (further lowering the hydraulic conductivity), but when applying a soil-based deformation-tracking water-blocking material as a water barrier Therefore, the design and construction in consideration of consolidation subsidence is required, such as predicting the amount of consolidation subsidence and raising the top of the soil-based deformation-following water shielding material.

On the other hand, the soil-based deformation-following water shielding material disclosed in Patent Documents 3 and 4 is disclosed in Patent Documents 1 and 2 because sand is used as a base material instead of marine clay. Although it is inferior in economic efficiency compared to existing soil-based deformation-following water-insulating materials, it is possible to solve the above-mentioned problems (procurement of marine clay, complexity of composition design and construction management, countermeasures for consolidation settlement) It has become. In this soil type deformation follow-up water shielding material, 1000 kg or more of sand is mixed per 1 m ^{3 of the} water shielding material, and the sand occupies about 40% or more of the volume of the water shielding material. Although mixing a large amount of sand in this way makes it possible to produce a water shielding material at a low cost, in the construction work, the sand tends to disperse unevenly, and the fluidity that can be applied is impaired, or sand particles However, there is a risk that the water blocking performance may be impaired by forming a continuous water channel.

  In addition, in this soil-based deformation-following water-insulating material, the clay portion that provides water-shielding performance is composed of a mixture of bentonite and fresh water, or a mixture of highly swellable bentonite and seawater, so the water content ratio as the clay portion Is very expensive. Nevertheless, the water permeability coefficient of the clay part can be kept low because most of the water in the clay part is used for the swelling of bentonite, so that there is little pore water that can freely pass through the clay part. It is known that the degree of swelling of bentonite is affected by the ionic concentration of pore water, etc., but in this soil-based deformation-following water-insulating material, the salt concentration or ionic concentration of pore water in the clay part is caused by water permeation. When the change occurs, the degree of swelling of bentonite decreases, and there is a possibility that the water shielding performance will decrease in the future.

  The present invention has been made in view of the above-described circumstances, and by using a standardized material, it is easy to procure the material, there is little variation in quality, high water shielding performance and flow that can be applied. It is an object of the present invention to provide a soil-based deformation-following water-insulating material having long-term durability in which the occurrence of consolidation settlement is suppressed and a method for producing the same.

In order to solve the above-mentioned problem, the structural features of the soil-based deformation-following water-shielding material according to claim 1 are a highly swellable bentonite having a swelling power in fresh water of 20 mL / 2 g or more, and the highly swellable Bentonite, which has a lower swelling power than bentonite, seawater, and sand having a uniformity coefficient of 5 to 10, is mixed, and when the total volume immediately after mixing is 1, the sand is 0.05 to 0. 0. 3 are included in a volume ratio, der permeability is 3 × 10 ^-7 cm / s or less immediately after mixing is, the bentonite swelling power than the high swelling bentonite is small, swelling power of the true water Is a low swellable bentonite of 5 mL / 2 g or less, and when the total mass of the high swellable bentonite and the low swellable bentonite is 1, the mass of the highly swellable bentonite is 0.05 to 0.3. It is included in the ratio .

The structural feature of the invention according to claim 2 is that in the soil-based deformation-following water shielding material according to claim 1, the shear strength immediately after mixing is 1.5 kN / m ² or less.

To solve the above problems, characteristic configuration on the method for producing a soil-based deformation following ability impermeable material according to claim 3, a high swelling bentonite swelling power is not less than 20 mL / 2 g of a true water, true a low swelling bentonite swelling power is less than 5 mL / 2 g in water and sea water, sand uniformity coefficient is 5 to 10, Ri Na were mixed, and the high swelling bentonite and the low swelling bentonite A method for producing a soil-based deformation-following water-impervious material in which the highly swellable bentonite is contained in a mass ratio of 0.05 to 0.3 when the total mass is 1 is: A curing process for submerging and curing, a water removing process for removing excess seawater from the sand after the curing process to make the sand wet, and a sand for mixing the wet sand after the water removing process A mixing step used as a The sand on the total volume of the immediately after mixing when a 1 is to mix so as to be contained at a volume ratio of 0.05 to 0.3.

The structural feature of the invention according to claim 4 is the method for producing a soil-based deformation-following water-insulating material according to claim 3, wherein the highly swellable bentonite and the lowly swellable bentonite are mixed with powder. A first mixing step for mixing in a state, a second mixing step for mixing the seawater with the material after the first mixing step, and a third mixing step for mixing the sand with the material after the second mixing step. That is.

  According to the configuration of the invention according to claim 1, all the constituent materials are standardized materials without using locally generated soil such as dredged clay as the constituent materials of the soil-based deformation follow-up water shielding material. Can do. For example, a highly swellable bentonite and a bentonite having a smaller swelling power than that of the highly swellable bentonite can be easily selected based on the value of the swelling force described in the test result table of commercially available bentonite. In addition, seawater can be easily obtained in the vicinity of the construction site in general with a seawater concentration of about 3%. Moreover, as sand whose uniformity coefficient is 5 to 10, for example, sand standardized as JIS A 5005 (crushed stone and crushed sand for concrete) or JIS A 5308 (ready mixed concrete) can be used. Sand can be easily obtained throughout Japan. Therefore, according to the present invention, by using a standardized material, it is easy to procure the material, and it is possible to reduce variations in the quality of the soil-based deformation follow-up water shielding material.

  In the case where the clay part providing the water shielding performance is made of a mixture of highly swellable bentonite and seawater, as in the soil-based deformation follow-up water shielding material disclosed in Patent Document 4, the water content ratio of the clay part is Become very expensive. On the other hand, according to the configuration of the present invention, the clay portion that provides the water shielding performance has a swelling power higher than that of the highly swellable bentonite having a swelling power in fresh water of 20 mL / 2 g or more. It consists of a mixture of small bentonite and seawater. That is, in the present invention, at least two or more bentonites having different swelling powers are used. Thus, the water content ratio of a clay part can be made small by containing bentonite with small swelling power in a clay part. And since the water content ratio of the clay part is small, the soil-based deformation-following water-impervious material suppresses the occurrence of consolidation settlement and provides a long-term water-impervious performance against changes in the ion concentration of pore water in the clay part. Can be maintained.

  Moreover, according to the structure of this invention, the soil system deformation | transformation followable water-impervious material has a volume of 0.05-0.3 sand whose uniformity coefficient is 5-10 when the total volume immediately after mixing is 1. Included in ratio. Therefore, the occurrence of consolidation settlement is suppressed in the soil-based deformation-following water-impervious material because the water content ratio is reduced by mixing sand. Here, when the volume ratio of sand is smaller than 0.05, the effect of suppressing the occurrence of consolidation settlement is hardly obtained. Moreover, when the volume ratio of sand is larger than 0.3, the fluidity of the soil-based deformation-following water-impervious material is remarkably lowered, and the construction becomes difficult. Sand having a uniformity coefficient of 5 to 10 has a wide particle size distribution width, and therefore sand is more easily dispersed in the clay portion than sand having a uniform particle size, and sand material separation is less likely to occur. Therefore, the soil-based deformation-following water-insulating material of the present invention is less likely to impair the fluidity of construction even when a lot of sand is mixed, and forms a water channel in which sand particles are continuous. Therefore, there is little risk of impairing the water shielding performance.

Moreover, according to the structure of this invention, the soil system deformation | transformation followable water-impervious material has a water permeability coefficient of 3 × 10 ⁻⁷ cm / s or less immediately after mixing. If the water permeability coefficient is 3 × 10 ⁻⁷ cm / s or less, the standard regarding the water shielding performance can be satisfied in the layer thickness of the general side surface water shielding work and the bottom surface water shielding work. Therefore, by setting the water permeability coefficient of the soil-based deformation-following water-insulating material to 3 × 10 ⁻⁷ cm / s or less, it is a highly versatile soil material for side-side and bottom-side water-insulating structures of various structures. It can be set as a system deformation follow-up water shielding material. Moreover, since it is necessary to reduce the water content ratio of the clay part in order to make the water permeability coefficient of the soil system deformation follow-up water shielding material 3 × 10 ⁻⁷ cm / s or less, the soil system deformation followability is required. Occurrence of consolidation settlement of the water shielding material is suppressed.

  As described above, according to the configuration of the present invention, it is easy to procure materials, have small variations in quality, have high water shielding performance and workable fluidity, and suppress the occurrence of consolidation settlement. In addition, it is possible to provide a soil-based deformation-following water shielding material having long-term durability. For convenience, bentonite having a swelling power in fresh water of 20 mL / 2 g or more is highly swellable bentonite, and bentonite having a swelling power in fresh water of greater than 5 mL / 2 g but less than 20 mL / 2 g is medium swellable bentonite in fresh water. The bentonite having a swelling power of 5 mL / 2 g or less is distinguished as a low swelling bentonite.

According to the configuration of the invention according to claim 1 , the bentonite having a swelling power smaller than that of the above-described highly-swellable bentonite is a low-swellable bentonite having a swelling power in fresh water of 5 mL / 2 g or less. Thus, the low moisture content bentonite with especially small swelling power is contained in the clay part, so that the moisture content of the clay part can be further reduced. And since the moisture content of the clay part can be further reduced, the soil-based deformation-following water-insulating material is more resistant to the occurrence of consolidation subsidence, and the water-insulating performance against changes in the ion concentration of pore water in the clay part. The effect of maintaining for a long time becomes more reliable.

According to the configuration of the invention according to claim 1 , when the total mass of the highly swellable bentonite and the low swellable bentonite is 1, the highly swellable bentonite is 0.05. It is included at a mass ratio of ˜0.3. When the water content ratio is adjusted so that the water permeability coefficient is uniform while changing the mass ratio of the highly swellable bentonite, if the mass ratio of the highly swellable bentonite is less than 0.05, the shear immediately after mixing the clay part The strength becomes too large, and it becomes difficult to secure the fluidity that can be constructed. The greater the mass ratio of the highly swellable bentonite, the higher the moisture content of the clay part, and the more conspicuous subsidence of the soil-based deformation following water-blocking material is promoted. On the other hand, workability is improved by reducing the shear strength. However, even if the mass ratio of the highly swellable bentonite is larger than 0.3, it becomes difficult to obtain an improvement effect of workability commensurate with the increase in the mass ratio, so the upper limit of the mass ratio of the highly swellable bentonite is 0. .3 is recommended.

According to the configuration of the invention according to claim 2, mixing shear strength immediately after the soil-based deformation following ability impermeable material is 1.5 kN / m ² or less. Therefore, since the fluidity of the soil-based deformation follow-up water shielding material can be ensured, good workability can be ensured with respect to the kneadability, pumpability, filling property, etc. of the soil-based deformation follow-up water shielding material.

According to the structure of the invention which concerns on Claim 3 , the sand of the wet state in which the surface of a sand particle is moistened with seawater is used as sand mixed with a soil type | system | group deformation followable water shielding material. In general, sand has a surface moisture content that varies depending on whether the sand particles are in a dry state, a dry surface, or a wet state due to fresh water (rain), depending on the conditions of carrying in and storage. . In this way, when the surface condition of the sand particles varies, air is entrained in the soil-based deformation-following water-impervious material, or the fresh water attached to the sand particles affects the degree of swelling of the bentonite. The quality of the deformable water-insulating material is not stable. According to the present invention, since the sand wet with seawater is used, the quality of the soil-based deformation-following water shielding material is stabilized.

According to the structure of the invention which concerns on Claim 4, after mixing a highly swellable bentonite and a low swellable bentonite in the state of a powder, it mixes in order of seawater and sand, and is a soil type | system | group deformation followable water-insulating material. Manufacturing. By kneading in such a procedure, the bentonite does not become lumpy and becomes a homogeneous bentonite slurry, and the sand is easily dispersed uniformly. Therefore, according to the present invention, the quality of the soil type deformation follow-up water shielding material is stabilized. It should be noted that if the procedure is different from this procedure, for example, when bentonite is gradually mixed with seawater, or when seawater is mixed after dry-mixing materials other than seawater, the mixing and stirring time is longer than that of the present invention. In some cases, and bentonite becomes lumpy and uniform mixing may become impossible.

It is sectional drawing of the revetment of a management type waste final disposal site. It is explanatory drawing explaining the manufacturing method of the soil type | system | group deformation | transformation followable water shielding material in one Embodiment. It is a graph explaining the water-blocking performance requested | required of a side water-impervious construction and a bottom face impermeable construction. It is a graph explaining the relationship between the water permeability of a highly swellable bentonite, a medium swellable bentonite, and a low swellable bentonite and a water content ratio. It is a graph explaining the relationship between the water content ratio of highly swellable bentonite, medium swellable bentonite, and low swellable bentonite and vane shear strength. FIG. 5 is a graph for determining the amount of highly swellable bentonite mixed with the soil-based deformation-following water-impervious material in one embodiment, showing the relationship between the mass ratio of highly swellable bentonite and vane shear strength. . It is a particle size accumulation curve of the sand mixed with the soil type | system | group deformation | transformation followable water shielding material in one Embodiment. It is a graph for determining the quantity of the sand mixed with the soil system deformation followable water shielding material in one embodiment, and shows the relation between the volume ratio of sand and the vane shear strength.

  Based on FIGS. 1-8, one Embodiment of this invention is described, adding an effect etc. as needed. The soil type deformation follow-up water shielding material D in the present embodiment is used as a side water-impervious work and a bottom water-impervious work of the management-type waste final disposal site 1 shown in FIG. That is, the application of the soil-based deformation follow-up water shielding material D in the present embodiment as a water-impervious work is the same as that of the conventional soil-based deformation follow-up water shielding material D. Since the structure and the like of the management-type waste final disposal site 1 shown in FIG. 1 are as described above, description thereof is omitted here.

  FIG. 2 is an explanatory diagram for explaining a method for manufacturing the soil-based deformation followable water shielding material D in the present embodiment. The soil-based deformation-following water-insulating material D is obtained by mixing high-swelling bentonite BH, low-swelling bentonite BL, seawater W, and sand S. Therefore, in this embodiment, the clay part which provides water-blocking performance consists of a mixture of the highly swellable bentonite BH, the low swellable bentonite BL, and the seawater W.

  The clay contains at least one clay mineral such as kaolinite, illite, montmorillonite (smectite), vermiculite, mica clay and the like. Among them, a material mainly composed of montmorillonite is generally called bentonite. Montmorillonite, particularly one in which the interlayer exchangeable cation is Na, exhibits remarkable swelling. The higher the swelling property, the more water is taken in between the unit layers of the clay mineral, so the pore water that can permeate freely through the clay portion is reduced and the water impermeability is increased.

  The degree of swelling of bentonite is expressed by the swelling power (JBAS-104-77). In this embodiment, for the sake of convenience, bentonite having a swelling power in fresh water of 20 mL / 2 g or more is highly swellable bentonite BH, and bentonite having a swelling power in fresh water of greater than 5 mL / 2 g but less than 20 mL / 2 g is moderately swellable. Bentonite BM and bentonite having a swelling power of 5 mL / 2 g or less in fresh water are distinguished as low swelling bentonite BL. Then, when the total mass of the high swellable bentonite BH and the low swellable bentonite BL is 1, the high swellable bentonite BH is mixed so as to be included at a mass ratio of 0.05 to 0.3.

As the seawater W, seawater W having a salinity of about 3% that can be obtained in the vicinity of the construction site is used. Sand S is the uniformity coefficient _{Uc (Uc = D 60 / D} 10) is 5 to 10, JIS A 5005 (for concrete crushed stone and crushed sand) or JIS A 5308 for concrete that has been standardized as (ready-mixed concrete) Use fine aggregate. The sand S is mixed so that the sand S is included in a volume ratio of 0.05 to 0.3 when the total volume of the soil-based deformation-following water shielding material D immediately after mixing is 1.

  Based on FIG. 2, the manufacturing method of the soil system deformation | transformation followable water shielding material D is demonstrated. The soil-based deformation-following water shielding material D is manufactured by on-site mixing in a manufacturing yard facing the sea. As shown in FIG. 2, the highly swellable bentonite BH is stored in the silo 10 for highly swellable bentonite, and the low swellable bentonite BL is stored in the silo 11 for low swellable bentonite. The high swellable bentonite BH and the low swellable bentonite BL are carried separately in a dry powder state, but they may be blended at a predetermined blending ratio at the shipping factory and stored in one silo. it can. The seawater W mixed with the soil system deformation followable water shielding material D is collected by using the submersible pump 12 from the quay near the manufacturing yard.

  The sand S is cured underwater until just before kneading in a state where it is submerged in the seawater W in the water tank 20. The sand S in the water tank 20 is scooped by the backhoe 21 and put into a vibrating sieve 22 having a screen with an opening of 0.075 mm. The vibrating sieve 22 removes excess seawater W from the sand S, and the sand S becomes wet with the seawater W adhering to the surface of the sand particles. The wet sand S is transferred to the hopper 23. The hopper 23 loaded with the sand S is lifted by the crawler crane 25, and the weight of the sand S is measured by the load cell 24.

  A batch mixer 30 is used for kneading the soil-based deformation-following water shielding material D. First, powdery high swellable bentonite BH and low swellable bentonite BL are weighed with a feeder or the like, put into a batch mixer 30 and lightly kneaded. Next, a predetermined amount of seawater W is charged into the batch mixer 30 and kneaded until a homogeneous bentonite slurry without lumps is obtained. The predetermined amount of seawater W is an amount obtained by subtracting the total amount of seawater W adhering to wet sand S from the content of seawater W in the blending design. Finally, a predetermined amount of wet sand S is put into the batch mixer 30 and kneaded again.

The soil-based deformation follow-up water shielding material D manufactured by the batch mixer 30 is put into an agitator tank 31 below the batch mixer 30, and is pumped and driven to a water shielding construction position by a squeeze pump 32. A measuring instrument 33 is installed in the pressure feeding pipe, and the measuring instrument 33 measures the flow rate and density of the soil system deformation follow-up water shielding material D. The soil-based deformation-following water shielding material D manufactured in this way has a permeability coefficient k immediately after mixing of 3 × 10 ⁻⁷ cm / s or less and a vane shear strength τ immediately after mixing of 1.5 kN / m. ² or less (hereinafter, the vane shear strength τ refers to the vane shear strength τ immediately after mixing).

  According to this embodiment, the sand S in the wet state in which the surface of the sand particles is wet with the seawater W is used as the sand S to be mixed with the soil-based deformation follow-up water shielding material D. Thereby, it is possible to prevent air from entraining the soil-based deformation following water-impervious material D and preventing the fresh water adhering to the sand particles from affecting the degree of swelling of bentonite. In addition, after mixing the high-swelling bentonite BH and the low-swelling bentonite BL in a powder state, the bentonite is mixed in the order of seawater W and sand S, and the bentonite becomes a homogeneous bentonite slurry without becoming lumpy. Sand S is also easy to disperse uniformly. Therefore, according to the manufacturing method of the soil type deformation follow-up water shielding material D in this embodiment, the quality of the soil type system deformation follow-up water shielding material D is stabilized.

Hereinafter, the process of determining the blending conditions of the soil-based deformation follow-up water shielding material D in the present embodiment will be described with additional effects and the like. The process of setting k = 1 × 10 ^{−7 to} 3 × 10 ⁻⁷ cm / s as the water permeability coefficient k of the soil-based deformation follow-up water shielding material D is as follows. FIG. 3 shows a graph for explaining the water shielding performance required for the side water-impervious work and the bottom water-impervious work. As described above, in Non-Patent Document 1, as a standard for the side water-impervious construction, an impervious material having a thickness of 50 cm or more and a water permeability coefficient of 1 × 10 ⁻⁶ cm / s or less, or equivalent or more impermeable water It is determined to have performance. Moreover, as a standard of the bottom impermeable construction, it is determined that it has a water impervious material having a thickness of 5 m (500 cm) or more and a water permeability coefficient of 1 × 10 ⁻⁵ cm / s or less, or a water impermeability equivalent to or higher than this. It has been.

Therefore, when the thickness L of the side impermeable construction is other than 50 cm and when the thickness L of the bottom impermeable construction is other than 500 cm, the water permeability coefficient k (necessary permeability coefficient) that satisfies the standard water shielding performance is obtained. It is necessary to calculate by calculation. In this calculation, it is considered that the longer the permeation time t required for water (contaminated water) to pass through the impermeable layer, the higher the water shielding performance, and the permeation time t is proportional to the square of the thickness L, A relational expression (t = L ² / (k · h), where h is a water level difference) that is inversely proportional to the water permeability coefficient k is used. The solid line in FIG. 3 shows the relationship between the thickness L of the water shielding layer that satisfies the water shielding performance of the side water shielding work and the water permeability coefficient k. Moreover, the broken line in FIG. 3 has shown the relationship between the thickness L of the water-impervious layer and the water permeability coefficient k which satisfy the water-impervious performance of the bottom impermeable construction. Moreover, the hatching in FIG. 3 indicates the range of the hydraulic conductivity k = 1 × 10 ^{−7 to} 3 × 10 ⁻⁷ cm / s.

As shown in FIG. 3, when the water permeability coefficient is k = 3 × 10 ⁻⁷ cm / s, as a side water-impervious work with a thickness L = 28 cm or more in calculation, the thickness of the water-impervious layer is calculated. The soil-based deformation follow-up water shielding material D can be applied as a bottom surface water shielding work of L = 87 cm or more. In general, the layer thickness L of the side water-impervious work and the bottom water-impervious work satisfies the layer thickness L shown on the left. Therefore, by determining the water permeability coefficient k of the soil-based deformation-following water-impervious material D to be 3 × 10 ⁻⁷ cm / s or less, it is versatile for side-surface and bottom-surface water-impervious structures having various structures. It can be set as the high soil-type deformation follow-up water shielding material D. When the water permeability coefficient is k = 1 × 10 ⁻⁷ cm / s, the soil-based deformation follow-up water shielding material D can be applied as a side water-impervious work having a thickness L = 16 cm or more of the water shielding layer. Since the layer thickness L of the side water-impervious work is considered not to be less than 16 cm, it is not necessary to set the water permeability coefficient k of the soil-based deformation-following water-impervious material D to less than 1 × 10 ⁻⁷ cm / s. .

  In the soil system deformation followable water shielding material D of the present embodiment, the clay portion that provides the water shielding performance is composed of a mixture of the highly swellable bentonite BH, the low swellable bentonite BL, and the seawater W. In selecting the bentonite used for the soil-based deformation-following water-insulating material D, as representatives of bentonites having different swelling powers, highly swellable bentonite BH (trade name: Tergel) and medium-swelling bentonite BM (shown in Table 1) Trade name: Tergel DL2) and low swelling bentonite BL (trade name: Kasaoka Clay) were selected candidates.

Table 1 also lists the liquid limit w _L as an index correlated with the swelling power. If the swelling property is high, the liquid limit w _L also becomes high. By the way, it is well known that montmorillonite, which is a main component of bentonite, has low swelling power in seawater W. In particular, those having a high swelling power have a high degree (swelling power in fresh water / swelling power in seawater), and conversely, those having a low swelling power have a low degree. That is, it can be said that the low-swelling bentonite BL has stable swelling even in a seawater environment and has high long-term durability regarding water-blocking performance as compared with the high-swellable bentonite BH.

FIG. 4 shows a graph in which each bentonite shown in Table 1 is kneaded with seawater W and subjected to a consolidation test, and is summarized as a relationship between the water permeability coefficient k and the water content ratio w. In FIG. 4, ◯ indicates the relationship between the highly swellable bentonite BH, □ indicates the medium swellable bentonite BM, and Δ indicates the relationship between the water permeability k and the water content w of the low swellable bentonite BL. Moreover, the continuous line in FIG. 4 has shown the approximate curve of the test result of each bentonite. The hatching in FIG. 4 indicates the range of the hydraulic conductivity k = 1 × 10 ^{−7 to} 3 × 10 ⁻⁷ cm / s. When the water content ratio w of each bentonite corresponding to a predetermined water permeability coefficient k is calculated based on each approximate curve shown in FIG. 4, it is as shown in Table 2. From FIG. 4 and Table 2, when the water content ratio w of each bentonite is compared at the same water permeability coefficient k, the water content ratio w is larger as the highly swellable bentonite.

As shown in Table 2, in the setting range k = 1 × 10 ^{−7 to} 3 × 10 ⁻⁷ cm / s of the water permeability coefficient k of the soil system deformation followable water shielding material D in the present embodiment, the liquid limit w _The ratio of the water content w to _L (w / w _L ) was 0.77 to 1.00. Next, with reference to the water content ratio w shown in Table 2, each bentonite is seawater W so that the water permeability coefficient is k = 1 × 10 ⁻⁷ , 2 × 10 ⁻⁷ , 3 × 10 ⁻⁷ cm / s. The water content ratio was adjusted by kneading. FIG. 5 is a graph illustrating the relationship between the water content ratio w and the vane shear strength τ of each bentonite slurry immediately after the water content ratio adjustment.

In FIG. 5, ◯ indicates the relationship between the highly swellable bentonite BH, □ indicates the medium swellable bentonite BM, and Δ indicates the relationship between the water content w of the low swellable bentonite BL and the vane shear strength τ. In addition, hatched hatching in FIG. 5 indicates target ranges of the water content ratio w and the vane shear strength τ. In this target range, the water content ratio w is set to 120% or less, for example, as the construction results of the soil-based deformation follow-up water shielding material disclosed in Patent Document 1, there are many results of the water content ratio w ≦ 120%. It depends. Further, in this target range, the vane shear strength τ is 1.5 kN / m ² or less. If this target range is satisfied, the kneadability, pumpability, and filling properties of the soil-based deformation-following water-insulating material D This is because it is considered that good workability can be secured. Note that this target range is an example, and it is desirable to set the target range as appropriate in consideration of the application structure, manufacturing method, construction method, and the like of the soil-based deformation follow-up water shielding material D.

  As shown in FIG. 4, the expected result is obtained that the permeability coefficient k is smaller as the water content w is lower for each bentonite. However, as shown in FIG. 5, the relationship between the water content ratio w and the vane shear strength τ does not show uniform characteristics for each bentonite. In this test range, for the medium swellable bentonite BM and the low swellable bentonite BL, the expected result is obtained that the vane shear strength τ is larger as the water content ratio w is smaller. The vane shear strength τ is substantially constant regardless of the water content w. That is, the highly swellable bentonite BH has unique strength characteristics compared to the medium swellable bentonite BM and the low swellable bentonite BL.

As shown in FIG. 5, when the water permeability coefficient k of each bentonite slurry is set to k = 1 × 10 ⁻⁷ , 2 × 10 ⁻⁷ , 3 × 10 ⁻⁷ cm / s, any bentonite is the target shown in FIG. Not satisfied with the range. Therefore, the present inventor prepares mixed bentonite satisfying the target range by blending high-swelling bentonite BH and medium-swelling bentonite BM, or blending high-swelling bentonite BH and low-swelling bentonite BL. I thought that might be possible. Then, as a preliminary study, after adjusting the water content ratio of each bentonite to a hydraulic conductivity k = 2 × 10 ⁻⁷ cm / s, the two types of bentonite slurry were blended in equal volumes (a ratio of 5: 5) and mixed. The vane shear strength τ of the bentonite slurry was measured. Table 3 shows the test results.

In Table 3, test case HM2-0505 is a test case using a blend of highly swellable bentonite BH and medium swellable bentonite BM. Here, “HM” in “HM2-0505” represents a blend of highly swellable bentonite BH and medium swellable bentonite BM. Further, “2” represents that the water permeability coefficient k = 2 × 10 ⁻⁷ cm / s. “0505” represents that each bentonite slurry is blended in an equal volume (a ratio of 5: 5). The same applies to test case HL2-0505.

As shown in Table 3, the mixing amount of highly swellable bentonite BH per 1 m ³ of mixed bentonite slurry in each test case is equal. In test case HM2-0505, although the water content ratio w is higher than in test case HL2-0505, the vane shear strength τ remains at the upper limit value τ of the target range τ = 1.5 kN / m ² . On the other hand, in the test case HL2-0505, although the water content ratio w is lower than that in the test case HM2-0505, the vane shear strength τ is τ = 0.75 kN / m ² within the target range. In test case HL2-0505, both the water content ratio w and the vane shear strength τ are within the target range.

  From this result, even when the highly swellable bentonite BH and the medium swellable bentonite BM are blended, it is possible to obtain the effect of bringing the water content w and the vane shear strength τ closer to the target range. It turned out that the effect was not remarkable. On the other hand, when the highly swellable bentonite BH and the low swellable bentonite BL having greatly different swelling forces are blended, the effect of bringing the water content ratio w and the vane shear strength τ closer to the target range is very high. all right. Therefore, in the present embodiment, a blend of the highly swellable bentonite BH and the low swellable bentonite BL is adopted.

In this embodiment, when the total mass of the highly swellable bentonite BH and the low swellable bentonite BL is 1, the high swellable bentonite BH is set to be included at a mass ratio of 0.05 to 0.3. The background is based on the following test results. After adjusting the water content ratio of the highly swellable bentonite BH and the low swellable bentonite BL to be the water permeability coefficient k = 1 × 10 ⁻⁷ , 2 × 10 ⁻⁷ , 3 × 10 ⁻⁷ cm / s, respectively, the same A slurry of a highly swellable bentonite BH having a water permeability coefficient k and a slurry of a low swellable bentonite BL are 10: 0, 8: 2, 6: 4, 5: 5, 4: 6, 2: 8, and 0:10. By blending at a volume ratio, the vane shear strength τ of the mixed bentonite slurry was measured. Table 4 and FIG. 6 show the test results.

In Table 4, for example, “HL” in the test case name “HL1-0802” represents a blend of high-swelling bentonite BH and low-swelling bentonite BL. Further, “1” indicates that the water permeability coefficient is k = 1 × 10 ⁻⁷ cm / s. “0802” indicates that the slurry of the highly swellable bentonite BH and the slurry of the low swellable bentonite BL are blended at a volume ratio of 8: 2. The same applies to the grounds for setting other test case names.

FIG. 6 shows the relationship between the mass ratio of highly swellable bentonite BH and the vane shear strength τ. When the mass of the highly swellable bentonite BH is m _BH and the mass of the low swellable bentonite BL is m _BL , the mass ratio of the highly swellable bentonite BH is represented by m _BH / (m _BH + m _BL ). A high volume ratio corresponding to a volume ratio of 10: 0, 8: 2, 6: 4, 5: 5, 4: 6, 2: 8, 0:10 between the slurry of the highly swellable bentonite BH and the slurry of the low swellable bentonite BL The mass ratios of the swellable bentonite BH are 1.00, 0.56, 0.32, 0.24, 0.17, 0.07, and 0, respectively.

In FIG. 6, a circle mark indicates a water permeability coefficient k = 1 × 10 ⁻⁷ cm / s, a square mark indicates a water permeability coefficient k = 2 × 10 ⁻⁷ cm / s, and a triangle mark indicates a water permeability coefficient k = 3 × 10 ⁻⁷ cm / s. The relationship between the mass ratio of highly swellable bentonite BH in s and the vane shear strength τ is shown. Moreover, the hatching in FIG. 6 indicates the set range of the mass ratio of the highly swellable bentonite BH and the target range of the vane shear strength τ in the present embodiment. As shown in FIG. 6, at any water permeability coefficient k, when the mass ratio of the highly swellable bentonite BH is smaller than 0.05, the vane shear strength τ is the upper limit of the target range of 1.5 kN / m. ^It is more than ² , and it becomes difficult to secure the fluidity that can be constructed.

  As the mass ratio of the highly swellable bentonite BH increases, the water content w of the mixed bentonite slurry (clay part) increases, and the occurrence of consolidation settlement of the soil-based deformation follow-up water shielding material D is promoted. On the other hand, when the vane shear strength τ of the mixed bentonite slurry is lowered, the workability of the soil type deformation follow-up water shielding material D is improved. However, as shown in FIG. 6, even if the mass ratio of the highly swellable bentonite BH is larger than 0.3, it becomes difficult to obtain an improvement effect of workability commensurate with the increase in the mass ratio. The upper limit of the mass ratio of bentonite BH is preferably 0.3.

  In the soil type deformation follow-up water shielding material D of the present embodiment, sand S having a uniformity coefficient Uc of 5 to 10 is included in a volume ratio of 0.05 to 0.3 when the total volume immediately after mixing is 1. The circumstances set to be based on the following test results. First, the first reason for using the sand S having the uniformity coefficient Uc of 5 to 10 is that the sand S is more uniform in the mixed bentonite slurry than the sand having a uniform particle size due to the wide particle size distribution width of the sand S. This is because it is easy to disperse in the sand and the material separation of the sand S hardly occurs. Uniformly dispersing the sand S in the soil-based deformation-following water-insulating material D ensures the fluidity of the soil-based deformation-following water-insulating material D and prevents the sand particles from forming a continuous water channel. There is an effect.

  The second reason for using the sand S having the uniformity coefficient Uc of 5 to 10 is that the material is easily available. As the sand S having a uniformity coefficient Uc of 5 to 10, for example, sand S standardized as JIS A 5005 (crushed stone and crushed sand for concrete) or JIS A 5308 (ready mixed concrete) can be used. Sand S can be easily obtained throughout Japan. FIG. 7 shows the particle size accumulation curve of the fine aggregate for concrete defined in JIS A 5005. As the sand S, the sand S whose particle size distribution falls within the range indicated by hatching in FIG. 7 can be used.

The process of setting the volume ratio of sand S to 0.05 to 0.3 is based on the following test results. After adjusting the water content ratio of the highly swellable bentonite BH and the low swellable bentonite BL to be the water permeability coefficient k = 1 × 10 ⁻⁷ , 2 × 10 ⁻⁷ , 3 × 10 ⁻⁷ cm / s, respectively, the same A blended bentonite slurry (clay part) is prepared by blending a slurry of a highly swellable bentonite BH having a water permeability coefficient k and a slurry of a low swellable bentonite BL at a volume ratio of 5: 5 (mass ratio of high swellable bentonite BH 0.24). ) Was produced. And the sand S was mixed with this mixed bentonite slurry, the soil type deformation follow-up water shielding material D was produced, and the vane shear strength (tau) of the soil type deformation follow-up water shielding material D was measured. The mixing amount of the sand S is 0, 0.05, 0.1, 0.2, 0.3, 0 for the sand S when the total volume immediately after mixing the soil-based deformation-following water shielding material D is 1. .4 in a volume ratio. Table 5 and FIG. 8 show the test results.

In Table 5, for example, “HLS” of the test case name “HLS2-05” indicates that the soil-based deformation-following water shielding material D includes high-swelling bentonite BH, low-swelling bentonite BL, and sand S. Represents. Further, “2” represents that the water permeability coefficient k = 2 × 10 ⁻⁷ cm / s. “05” represents that the volume ratio of the sand S is 0.05. The same applies to the grounds for setting other test case names.

FIG. 8 shows the relationship between the volume ratio of the sand S and the vane shear strength τ. When the volume of the substantial part of the highly swellable bentonite BH is V _BH , the volume of the substantial part of the low swellable bentonite BL is V _BL , the volume of the seawater W is V _W , and the volume of the substantial part of the sand S is V _S , The volume ratio of the sand S is expressed by V _S / (V _BH + V _BL + V _W + V _S ). In FIG. 8, the ◯ marks indicate the permeability coefficient k = 1 × 10 ⁻⁷ cm / s, the □ marks indicate the permeability coefficient k = 2 × 10 ⁻⁷ cm / s, and the Δ marks indicate the permeability coefficient k = 3 × 10 ⁻⁷ cm / s. The relationship between the volume ratio of sand S in s and the vane shear strength τ is shown. Further, hatched hatching in FIG. 8 indicates the setting range of the volume ratio of the sand S and the target range of the vane shear strength τ in the present embodiment.

  As shown in FIG. 8, as the volume ratio of the sand S increases, the vane shear strength τ also increases. And since the moisture content w becomes small by mixing of sand S, generation | occurrence | production of consolidation settlement is suppressed by the soil system deformation | transformation followable water shielding material D. Here, when the volume ratio of the sand S is smaller than 0.05, it is considered that the effect of suppressing the occurrence of consolidation settlement due to the mixing of the sand S is hardly obtained. Further, when the volume ratio of the sand S is larger than 0.3, the vane shear strength τ is remarkably increased. Therefore, when the volume ratio of the sand S is larger than 0.3, it is considered that the fluidity of the soil-based deformation follow-up water shielding material D is remarkably lowered and the construction becomes difficult. It should be 0.3.

  As described above, the soil-based deformation-following water shielding material D of the present embodiment is a mixture of the highly swellable bentonite BH, the low swellable bentonite BL, the seawater W, and the sand S. For this reason, standardized materials can be used without using locally generated soil such as dredged clay as a constituent material. Water material D can be provided. In addition, the range of the optimal mass ratio of the highly swellable bentonite BH and the optimal sand S so that both the water content ratio w and the vane shear strength τ of the soil-based deformation-following water shielding material D are minimized. Since the volume ratio range is set, it provides a soil-based deformation-following water-insulating material D that has high water-insulating performance and workable fluidity, and has long-term durability in which the occurrence of consolidation settlement is suppressed. can do.

  The soil-based deformation-following water shielding material and the production method thereof according to the present invention are not limited to the above-described embodiment, and modifications, improvements, etc. that can be made by those skilled in the art are within the scope not departing from the gist of the present invention. Needless to say, the present invention can be implemented in various forms.

  For example, in the soil-based deformation follow-up water shielding material D of the present embodiment, the mixed bentonite slurry (clay part) that provides the water shielding performance is composed of a highly swellable bentonite BH, a low swellable bentonite BL, and seawater W. It is also possible to use medium-swelling bentonite BM instead of low-swelling bentonite BL.

  Moreover, in the manufacturing method of the soil system deformation | transformation followable water-insulating material D of this embodiment, after mixing highly swellable bentonite BH and low swellable bentonite BL in the state of a powder, seawater W and sand S are carried out in order. Although they are mixed, the manufacturing method is not limited to this. For example, after a predetermined amount of powdery low-swelling bentonite BL is charged into the batch mixer 30, a predetermined amount of seawater W is charged into the batch mixer 30 and kneaded until a homogeneous bentonite slurry free of lumps is obtained. Next, a predetermined amount of powdery highly swellable bentonite BH is added to the bentonite slurry, and then kneaded by the batch mixer 30 until a homogeneous bentonite slurry without lumps is obtained. Finally, a manufacturing method in which a predetermined amount of wet sand S is put into the batch mixer 30 and kneaded again can be employed.

BH ... mass of highly swellable bentonite BL ... low swelling bentonite BM ... Medium swellable bentonite D ... mass m _BL ... low swelling bentonite soil-based deformation following ability water shield member k ... Permeability m _BH ... highly swellable bentonite S ... sand V _BH ... volume V _BL ... volume V _S ... volume V _w ... volume W ... seawater τ ... vane shear strength of the sea of sand of low-swelling bentonite of high swelling bentonite

Claims (4)

A highly swellable bentonite having a swelling power in fresh water of 20 mL / 2 g or more, a bentonite having a swelling power smaller than that of the highly swellable bentonite, seawater, and sand having an equality coefficient of 5 to 10 are mixed. Become
When the total volume immediately after mixing is 1, the sand is included in a volume ratio of 0.05 to 0.3,
The hydraulic conductivity immediately after mixing is 3 × 10 ⁻⁷ cm / s or less,
The bentonite having a lower swelling power than the highly swellable bentonite is a low swelling bentonite having a swelling power in fresh water of 5 mL / 2 g or less,
Soil-based deformation following water-impervation containing the high-swelling bentonite in a mass ratio of 0.05 to 0.3 when the total mass of the high-swelling bentonite and the low-swelling bentonite is 1. Wood. The soil-based deformation following water-impervious material according to claim 1, wherein the shear strength immediately after mixing is 1.5 kN / m ² or less. High-swelling bentonite having a swelling power in fresh water of 20 mL / 2 g or more, low-swelling bentonite having a swelling power in fresh water of 5 mL / 2 g or less , seawater, and sand having an equality coefficient of 5 to 10, Ri Na were mixed, high-swelling bentonite is contained at a weight ratio of 0.05 to 0.3 when the total mass of the high swelling bentonite and the low-swelling bentonites 1 A method for producing a soil-based deformation-following water shielding material,
Curing process in which the sand is submerged in seawater, a water removing process for removing excess seawater from the sand after the curing process to make the sand wet, and the wet sand after the water removing process A mixing step used as sand for mixing,
A method for producing a soil-based deformation-following water shielding material, wherein the sand is mixed so that the sand is included in a volume ratio of 0.05 to 0.3 when the total volume immediately after mixing is 1 in the mixing step. A first mixing step of mixing the high-swelling bentonite and the low-swelling bentonite in a powder state, a second mixing step of mixing the seawater into the material after the first mixing step, and a second mixing The manufacturing method of the soil type | system | group deformation followable water shielding material of Claim 3 including the 3rd mixing process of mixing the said sand with the material after a process.

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