JP2013136938A - Underground continuous cut-off wall method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underground continuous cut-off wall method in which an underground continuous cut-off wall is established by a wall composition using a smectite clay mineral granular materials as a main component, regarding the impervious performance of the underground continuous cut-off wall, and in which the underground continuous cut-off wall has self-repair performance for a crack due to water absorption and expansivity of the smectite clay mineral granular material when the wall is cracked.SOLUTION: The underground continuous cut-off wall method comprises a step of digging and mixing by using bubble-mixed earth obtained by adding bubble or bubble and water, as a stabilizer, and a replacement step of sending a wall composition to the bottom of the dug part so as to replace the bubble-mixed earth with the wall composition after completion of the digging and mixing step. In the method, the wet density of the bubble-mixed earth at the time of digging and mixing is adjusted to be in a range from 1.03-1.72 g/cm, and the wall composition to be used in the replacement step is obtained by mixing a smectite clay mineral granular material with water or with water and bubble.

Description

  The present invention relates to an underground continuous water blocking wall construction method.

  Soil cement underground water barriers prevent the release of harmful substances from temporary earth retaining walls for constructing structures, water barriers for underground dams for storing groundwater, and factory sites contaminated with harmful substances. It is used for various purposes as a water blocking wall for blocking.

  Soil cement underground continuous water barrier construction methods are roughly classified into in-situ mixing and agitation methods and replacement methods depending on the wall construction method. The in-situ mixing agitation method is a method of using cement slurry as a stabilizing liquid in order to keep the groove wall stable during excavation, mixing and agitating excavated soil and cement slurry, and solidifying the mixed soil.

  The replacement method uses bentonite stabilizer as the stabilizer, excavates using an excavator for the reinforced concrete underground continuous wall, mixes the agitation soil and cement slurry, and stirs the soil cement composition into the bentonite stable It is a construction method that constructs soil cement underground continuous walls by replacing with liquid. Since the quality of the water-stop wall by the replacement method is good, it is often applied to a water-stop wall that is deep and highly watertight.

  In these construction methods, the wall material of the water barrier wall is a material in which excavated soil is the main material and solidified material is mixed and kneaded. Depending on the physical properties of the excavated soil, the performance required for the water barrier wall is not sufficient. It cannot be said that the composition is full. In addition, conventional soil cement underground water barriers have been designed with certain design properties for strength and hydraulic conductivity, but they have certain physical properties, but cracks are generated by external forces such as earthquakes, resulting in water leakage. There is no consideration for this, and much less self-healing function.

Japanese Patent No. 4342558

  The present invention has been made in view of the circumstances as described above, and relates to the water barrier properties of the underground continuous water blocking wall. When a water wall is built and cracks occur in the underground continuous water barrier, the underground continuous water barrier construction method with self-healing ability of cracks is provided by the water absorption and expansion of the smectite clay mineral granular material. The task is to do.

  The present invention is characterized by the following in order to solve the above problems.

First, after completion of excavation, mixing process, excavation, mixing process, and excavation, mixing process with the foam or mixed gas with the addition of air bubbles or air bubbles and water as a stable liquid, the wall-forming composition is sent to the bottom of the excavation, An underground continuous waterstop wall construction method comprising a substituting process for substituting the mixed soil and the wall-forming composition, wherein the foam mixed soil has a wet density in the range of 1.03 to 1.72 g / cm ³ when excavated and mixed. The wall-forming composition used in the replacement step is a wall-forming composition obtained by kneading smectite-based clay mineral particles and water, or smectite-based clay mineral particles, water and bubbles. It is an underground continuous water barrier method.

  Secondly, in the underground continuous water blocking wall construction method of the first invention, in the excavation and mixing, the bubble mixed soil whose wet density is adjusted, the smectite clay mineral granule and water, or the smectite clay mineral granule A wall-forming composition kneaded with water and bubbles is used as a wall-forming composition.

  Third, in the underground continuous water blocking wall construction method of the first or second invention, the smectite clay mineral particles are immersed in a water-soluble resin having a concentration of 1 to 10%, dried, and the surface thereof is water-soluble. Smectite clay mineral particles coated with resin are used.

  Fourth, in the underground continuous water blocking wall construction method of the first or second invention, the smectite clay in which the smectite clay mineral particles are dipped in cement milk and dried, and the surface thereof is coated with the cement aggregate. Use mineral granules.

  Fifth, in the underground continuous water blocking wall construction method of the first or second invention, the smectite clay mineral particles are immersed in 70-100% sodium oxalate and dried, and the surface is oxalic acid. Smectite clay mineral particles coated with soda solidified material are used.

  Sixth, in the underground continuous water blocking wall construction method of the first or second invention, the smectite clay mineral in which the smectite clay mineral particles are immersed in an oil and fat solution and dried, and the surface thereof is coated with the oil and fat body. Use granules.

  Seventh, in the underground continuous water blocking wall construction method of the first to sixth inventions, drying is performed by adding any combination of clay, silt, sand, gravel and fly ash to the smectite clay mineral granular material. A wall-forming composition having a high density is used.

  Eighth, in the underground continuous water blocking wall construction method of the first to seventh inventions, the smectite clay mineral granule crushes the raw ore or granulates from the powder to adjust the water content ratio and the particle size Smectite clay mineral granule.

  Ninth, in the underground continuous water blocking wall construction method of the first to eighth inventions, a solidifying material is added to the wall-forming composition.

  Tenth, in the underground continuous waterstop wall construction method of the first to ninth inventions, a member for reinforcing the structure is inserted into the wall-forming composition while the wall-forming composition is unconsolidated. , Increase the strength of continuous underground water barrier.

  Eleventhly, in the underground continuous water blocking wall construction method of the first to ninth inventions, as a means for replacing the bubble-mixed soil and the wall-forming composition, the wall-forming composition is sent to the bottom of the excavation, and the wall-making is made by Tremy. The composition is fed to the bottom of the bubbling excavation soil and replaced using the difference in specific gravity.

  Twelfth, in the underground continuous waterstop wall construction method of the first to ninth inventions, the wall-forming composition is fed to the bottom of excavation, and a spiral auger is incorporated as a means for replacing the bubble-mixed soil and the wall-forming composition. The walled composition is forcibly discharged and replaced into the bubble-mixed soil by rotating the spiral auger with a power machine.

  According to the underground continuous water blocking wall method of the present invention, the underground continuous water blocking wall is constructed with a wall-forming composition mainly composed of smectite clay mineral particles, so that the underground continuous water wall is continuously generated by an external force such as an earthquake. Even if the water blocking wall is cracked and water enters, the smectite clay mineral particulates can absorb water and expand to develop a function of self-repairing the crack.

It is the schematic which showed the underground continuous water stop wall construction method of this invention. It is a graph which shows the expansion pressure by the water absorption of the bentonite granular material by elapsed time 0-3500 minutes. It is the graph which showed the elapsed time of 0-200 minutes of FIG. It is the graph which showed the relationship of the passage mass percentage with respect to a particle size.

  Below, the underground continuous water stop wall construction method of this invention is explained in full detail.

  The underground continuous waterstop wall construction method of the present invention is a wall-forming composition after excavation, mixing step, excavation, mixing step and completion of excavation, mixing step, excavating and mixing with air bubbles or air bubble mixed soil added with air bubbles and water. Is a construction method consisting of a replacement step in which the air is mixed into the bottom of excavation to replace the bubble-mixed soil and the wall-forming composition.

  First, the excavation and mixing process will be described with reference to FIG.

In the excavation and mixing step of the present invention, excavation and mixing are performed while adding bubbles from the tip of the excavator of the underground continuous wall construction machine 1 to create the bubble mixed soil 2 in which the bubbles and the excavated soil are mixed. The wet density of the cell-mixed soil 2 is smaller than the wall-forming composition 3 to be replaced in the replacement step (I, II) described later, and is larger than 1.03 g / cm ^{3 in} order to keep the groove wall stable. In addition, adjustment is performed according to the amount of bubbles or the amount of bubbles and water added.

Here, as specific conditions in which the wet density of the bubble mixed soil 2 is lower than that of the wall-forming composition 3 to be replaced in the replacement step, a numerical value based on data obtained from experience is used, The upper limit of the wet density of the composition 3 can be 1.72 g / cm ³ .

  In addition, the wet density and bubble addition amount of the bubble mixed soil 2 can be calculated based on the following formula (1).

Here, γ _c is the wet density (g / cm ³ ) of the bubble mixed soil, w is the water content ratio (%) of the bubble mixed soil, Q is the bubble addition rate (%), and γ _s is the density of the soil particles (g / cm cm ³ ), γ _w represents the density of water (g / cm ³ ), and γ _b represents the density of bubbles (g / cm ³ ).

  The bubble addition rate Q can be expressed by the following formula (2).

The bubbles used here are bubbles obtained by foaming a foaming agent with 24 times air, and the physical property values of the excavated soil include kneadability and separability, and the physical property value is a density of 0.04 g / cm ³ and an average particle diameter. Is preferably 500 μm or less. The density of the soil particles of excavated soil is generally is 2.6~2.7g / cm ^3, easily reduce the wet density of the bubbles mixed soil 2 the density is mixed bubbles 0.04 g / cm ³ to excavated soil Can be made.

  Further, by mixing the bubbles, the fluidity of the bubble mixed soil 2 is improved, so that the replacement with the wall-forming composition 3 in the replacement step is facilitated.

In addition, it is clear in the patent (patent No. 3725750) by the present inventors that the bubble mixed soil 2 is effective as a stabilizing liquid during excavation. It is known that it is necessary to keep the wet density of the soil 2 at 1.03 g / cm ³ or more.

In addition, when the ground for constructing a continuous water barrier is below the groundwater level, it is possible to easily create the bubble-mixed soil 2 by adding only bubbles. Since it occurs, water is added together with the addition of bubbles, but if the amount of water is large, there is a possibility that the bubble mixed soil will be separated. Therefore, it is desirable to limit the addition to about 50 to 100 L per 1 m ^{3 of} excavated soil.

When the amount of bubbles necessary to obtain the minimum wet density of 1.03 g / cm ³ of the bubble mixed soil 2 for stabilizing the pore wall is calculated from the equation (1), it is approximately 780 L in the sandy soil per 1 m ^{3 of} the excavated soil. In viscous soil, it is approximately 550L.

  In addition, the underground continuous wall construction machine 1 used for construction of the excavation and mixing process of the present invention is not particularly limited. For example, a constant thickness soil used for construction of soil cement underground continuous wall Cement underground continuous wall construction machines and underground continuous wall construction machines used for the construction of column row soil cement underground continuous walls can be used, and among these, the wall thickness can be made constant. Thus, an iso-thickness soil cement underground continuous wall construction machine can be suitably used.

  Next, after completion of the excavation and mixing process, the wall-forming composition 3 is sent to the bottom of the excavation, and the process proceeds to a replacement process in which the bubble mixed soil 2 and the wall-forming composition 3 are replaced.

  The wall-forming composition 3 used in the replacement step is a wall-forming composition 3 in which smectite-based clay mineral particles and water, or smectite-based clay mineral particles, water and bubbles are kneaded.

The wall-forming composition 3 is approximately 1: 1 to 1: 0.5, preferably 1: 0.6, in a weight ratio of the smectite clay mineral particles and water in an air-dried state by the above-mentioned kneader 4. The composition was adjusted by mixing in the range of. The wet density of the wall-forming composition 3 adjusted under such conditions is about 1.46 to 1.72 g / cm ³ . Further, the wall-forming composition 3 in which bubbles are further added to the smectite-based clay mineral particles and water increases the fluidity, so that the replacement work can be facilitated.

  In addition, when powder is used as the shape of the smectite clay mineral, when the powder is mixed with water, the powder immediately absorbs water and starts to expand and the viscosity increases. For this reason, for example, even when smectite clay and water are mixed at a weight ratio of 1: 0.6, they rapidly form dumplings, which makes it difficult to knead and replace with Tremy 5. However, when a large amount of water is used, the smectite clay absorbs water during kneading and ends expansion, so that self-repairability due to water absorption and expansion cannot be expected.

  Therefore, it is necessary to use a smectite clay mineral granule. In this case, only the surface of the smectite clay mineral granule in the wall-forming composition 3 absorbs water, and bubbles are formed using the tremy 5. The smectite clay mineral particles in the wall-forming composition 3 can be replaced with the mixed soil 2 and absorb kneaded water and underground water and expand to construct an underground continuous water blocking wall.

  The smectite clay mineral particles are desirably smectite clay mineral particles having a moisture content close to an air-dried state in order to absorb more water in the ground and expand.

  Further, the smectite clay mineral granules used in the present invention may be smectite clay mineral granules obtained by crushing raw ore or granulating from powder and adjusting the water content ratio and particle size, and are particularly economical. From such a viewpoint, it is desirable to use a smectite clay mineral granular material obtained by pulverizing raw ore.

  Further, in the present invention, the cell mixing composition 2 in which the wet density is adjusted during excavation and mixing, and the above-mentioned smectite clay mineral granular material and water, or the smectite clay mineral granular material, water and bubbles are kneaded. 3 can also be used.

  In this case, an expansion test is performed using a mixture of the bubble mixed soil 2 discharged on the ground and the smectite clay mineral granular material as a test piece, and it is confirmed that an expansion pressure higher than the earth pressure of the groove wall is obtained. Therefore, it is desirable to use the wall-forming composition 3.

  Further, in the present invention, the smectite clay mineral granular material is previously immersed in a water-soluble resin, cement milk, sodium oxalate, or oil and fat, and dried, and the surface thereof is water-soluble resin, cement milk, sodium oxalate, or Smectite clay mineral particles coated and impregnated with an oil / fat liquid can be used.

  When the dried smectite clay mineral particles are mixed with water, they immediately start to absorb water and increase in viscosity, so that replacement becomes difficult over time. Therefore, by delaying the smectite clay mineral particles in a 1-10% water-soluble resin for a short time, drying, and coating the surface of the smectite clay mineral particles with the water-soluble resin, the water absorption start time is delayed. Therefore, it is possible to allow time for kneading and replacement work of the wall-forming composition 3.

  As the water-soluble resin that coats the surface of the smectite clay mineral granular material, any known water-soluble resin can be used without limitation. For example, as a synthetic polymer, polyvinyl alcohol, polyacrylamide, sodium polyacrylate, Examples of semisynthetic polymers such as polyethyleneimine, polyethylene oxide, and polyvinylpyrrolidone include carboxymethylcellulose, hydroxyethylcellulose, and oxidized starch, and examples of natural polymers include alginic acid.

  Among these, polyvinyl alcohol can be preferably used. Polyvinyl alcohol having a polymerization degree of 100 to 400 and a saponification degree (mol%) of 88 to 90 (manufactured by Nippon Acetate / Poval Co., Ltd.) : Anion-modified PVA AP-17) has characteristics such as being easily soluble in water and good stability of clay, and can be particularly preferably used.

  In the present invention, the smectite clay mineral particles are immersed in cement milk, sodium oxalate, or an oil and fat solution and dried, and the surfaces thereof are respectively coated with cement aggregate, sodium oxalate solidified body, or oil body. Impregnated smectite clay mineral particles can also be used.

  This treatment is similar to the treatment with the water-soluble resin described above, by temporarily delaying the intrusion of water into the smectite clay mineral granule, thereby preventing the degree of soft mud and providing a sufficient time for construction. In addition, a film of cement aggregate, sodium oxalate solidified body or oil body is formed on the surface of bentonite granular body in an air-dried state.

  Cement milk, sodium oxalate, or oil / fat liquid by immersing solid clay mineral particles in cement milk, sodium oxalate, or oil / fat, adhering cement milk, sodium oxalate or oil / fat liquid, and drying. It has been confirmed that it takes at least 100 minutes for water to pass through the coating and reach the solid clay mineral granules.

  The ratio of cement to water for forming a cement coating on the air-dried clay mineral granules is preferably in the range of about 40 to 80%, more preferably about 50%. If the ratio of water and cement is within this range, a cement film is sufficiently formed, and particles of solid clay mineral particles do not adhere to each other, and a high-quality solid material can be obtained.

  Moreover, as sodium oxalate which coat | covers the surface of a smectite clay mineral granular material, if it is a conventionally well-known sodium oxalate, it can be used without a restriction | limiting and can be used by diluting to a 70-100% density | concentration.

  Among these, sodium oxalate No. 3 used for ground improvement and the like is inexpensive and can be suitably used because it is easily available.

  As the oil / fat liquid covering the surface of the smectite clay mineral granular material, any ordinary oil / fat can be used without limitation, and examples thereof include edible oils, machine oils, and water-soluble cutting oils. .

  Furthermore, in this invention, it can be set as the wall-forming composition 3 which made dry density large by adding in combination with any of clay, silt, sand, gravel, and fly ash to a smectite clay mineral granular material.

  In addition, according to the standards (JSF) of the Japan Society for Geotechnical Engineering, sand is defined as having a particle size of 0.075 to 2 mm, and gravel is defined as having a particle size of 2 mm or more. The sand and gravel used in the present invention are also compliant with this. is there.

  By increasing the blending amount of the smectite clay mineral particles in the wall-forming composition 3 and increasing the dry density, the expansion pressure when the smectite clay mineral particles are absorbed and expanded by water increases, so it is more stable. A continuous underground water barrier can be constructed.

  The drying density and the expansion pressure can be increased by improving the particle size distribution of the wall-forming composition 3. In order to exhibit this effect, it is desirable that the particle size distribution satisfies the following formula (3).

  Uc represents a uniformity coefficient, Uc ′ represents a curvature coefficient, and these are defined by a soil grain size test method (JSF T 131-1990).

  According to this, Uc is represented by the following formula (4), and Uc ′ is represented by the following formula (5).

Uc = D ₆₀ / D ₁₀ (4)
Uc ′ = (D ₃₀ ) ² / (D ₁₀ × D ₆₀ ) (5)
Here, D ₁₀ , D ₃₀ , and D ₆₀ represent the particle diameter D (mm) with respect to the passing mass percentage of 10%, 30%, and 60% from the particle diameter accumulation curve.

  The uniformity coefficient Uc represents the gradient of the particle size accumulation curve, and the larger the particle size distribution, the wider the particle size distribution. In general, soil having Uc of 4 to 5 or less is regarded as “poor particle size distribution”, and soil of 10 or more is regarded as “good particle size distribution”. These expressions correspond to the degree of soil compaction difficulty. Further, the curvature coefficient Uc ′ indicates the smoothness of the particle size accumulation curve, and when Uc ′ is 1 to 3, “the particle size distribution is good”. That is, in order to “good particle size distribution”, it is necessary to satisfy the above-mentioned conditions for Uc and Uc ′ simultaneously.

  Moreover, in this invention, when it is necessary to ask | require intensity | strength for an underground continuous water stop wall, a strong underground continuous water stop wall body is obtained by adding and using cement as a solidification material to the wall-forming composition 3. It can also be constructed.

  Furthermore, in the underground continuous water blocking wall method of the present invention, when the underground continuous water blocking wall composed only of the wall forming composition 3 is required to be used as a structure, the wall forming composition 3 In the unsolidified state, a member that reinforces the structure such as H-shaped steel or sheet pile can be inserted into the wall-forming composition 3 to increase the strength of the underground continuous water blocking wall.

  As the means used in the replacement process, as shown in 2) replacement process I of FIG. 1, the wall-forming composition 3 and the cell-mixed soil 2 are used by using the tremy 5 which is usually used for placing concrete in the underground continuous wall construction method. Can be used to place the wall-forming composition 3 into the bubble-mixed soil 2, but when the specific gravity difference is small and replacement is difficult, 3) in FIG. As shown, a spiral auger 7 can be used as a method for forcibly discharging and replacing the wall-forming composition 3.

  As a means for replacing the bubble-mixed soil 2 and the wall-forming composition 3, the spiral auger 7 that is rotated by the power machine 8 is incorporated in the tremey 5, and the wall-forming composition 6 put on the top of the tremy 5 is rotated by the rotation of the spiral auger 7. From the tip of the tremy 5, it is forcibly discharged into the bubble mixing soil 2 at the bottom of the excavation part, pulled out to the top while replacing the bubble mixing soil 2, and further moved in the horizontal direction so that the entire continuous underground water blocking wall This is a replacement process filled with the wall-forming composition 3, and as a result, it is possible to increase the density and quality of the underground continuous water blocking wall.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all.

In the following, an expansion test, a coating test, a particle size blending test, and a water permeability test conducted to confirm the effect of the underground continuous water blocking wall method of the present invention will be described in detail.
<Expansion test>
As for the expansion pressure due to water absorption of the smectite clay mineral granular material, the following expansion test was conducted assuming water absorption and expansion of the wall-forming composition under the restraint pressure due to earth pressure from the groove wall.

  The test apparatus uses a compaction tester used in a soil compaction test in accordance with JIS A 1217: 2009, and the specimen is a smectite clay mineral, which is a typical clay mineral bentonite ore. Samples 1 to 7 for preparing specimens using air-dried granules having a particle size of 10 mm and 20 mm were prepared.

Each of these samples 1 to 7 was put in a cylindrical compacting ring and lightly tightened to obtain a specimen for an expansion test. A displacement meter and a loading device for measuring expansion pressure were attached to the upper part of the specimen to measure the amount of expansion.
Table 1 shows the dimensions of the test apparatus, the initial state of the sample, and the blending amount.

  When water supply is started from the lower end of each specimen, the bentonite starts to absorb water and expand, so that the amount of expansion is always adjusted to 1/100 mm or less by adjusting the applied pressure, and this applied pressure is taken as the expansion pressure. Table 2 shows the state of the sample at the end of the expansion test, and FIGS. 2 and 3 show graphs of the expansion test results (relationship between time and expansion pressure).

  FIG. 2 shows the expansion pressure due to water absorption of bentonite granules having an elapsed time of 0-3500 minutes, and FIG. 3 shows the elapsed time of 0-200 minutes in FIG.

Samples 1 shown in FIGS. 2 and 3 show the relationship between time and expansion pressure when only bentonite granules having a maximum particle size of 10 mm are used. According to this graph, the expansion starts at the same time as the water absorption, the expansion pressure starts to increase, the increase in the expansion pressure becomes moderate after about 50 minutes, and the expansion pressure becomes 150 kN / m ² after 1360 minutes.

The water content of the specimen at the start of water supply was 0.3%, but the water content after 1360 minutes was 65.9%. Although the expansion of bentonite varies depending on the content, it can be said that the water content ratio is still about 200 to 300%, so that the water content ratio still causes sufficient expansion.
<Coating test>
A coating test was conducted to confirm the effectiveness of water-soluble resin, cement milk, sodium oxalate, or bentonite granules treated with an oil / fat liquid.

  As a water-soluble resin, polyvinyl alcohol (trade name: AP-17, manufactured by Nippon Vinegar Poval Co., Ltd., trade name: AP-17) has an ultralow polymerization degree of 100 to 400 and a saponification degree (mol%) of 2 to 90%. Ordinary Portland cement as a cement milk to 40% water cement milk, sodium oxalate No. 3 as a sodium oxalate solution, water-soluble cutting oil as fats and oils (trade name No. 824, manufactured by AZET Co., Ltd.) A bentonite granule having a maximum particle size of 20 mm, which is a smectite clay mineral, is dipped in the stock solution for 1 second, dried in the air, and coated with polyvinyl alcohol, cement milk, sodium oxalate, and an oil liquid on the surface, respectively. Was created.

The result of the expansion test of Samples 4 to 7 prepared using the bentonite granules coated on the surface is shown in FIG. From this result, compared to Samples 1 to 3 that do not cover the surface, the expression of water absorption expansion pressure of Samples 4 to 7 that cover the surface is delayed, and the smectite clay mineral particles that cover the surface can be used effectively. confirmed.
<Particle size blending test>
Table 1 shows the blending ratio of the bentonite granules and cinnabar sand of Samples 1 to 7, and FIG. 4 shows the relationship of the passing mass percentage.

  Sample 1 is a sample made only of bentonite granules having a maximum particle size of 10 mm or less. Sample 2 is a sample in which the bentonite granules of sample 1 are mixed at a weight ratio of 75% and dredged sand No. 6 at a weight ratio of 25%. Sample 1 was a mixture of 60% bentonite granules, 20% cinnabar No. 5 and 20% cinnabar 6 in weight ratio, and samples 4, 5, 6, and 7 were bentonite granules having a maximum particle size of 20 mm. Is a sample in which smectite clay mineral particles coated with polyvinyl alcohol, cement milk, sodium silicate and water-soluble cutting fluid are mixed in a weight ratio of 57% and cinnabar No. 3 in a weight ratio of 43%.

According to Table 2 and FIG. 2, the samples 2 and 3 with good particle size distribution satisfying the expressions 4 and 5 have a larger expansion pressure than the samples 1, 4, 5, 6, and 7 with poor particle size distribution, so It was confirmed that it was effective.
<Water permeability test>
Further, when a water permeability test was performed on samples 2, 3 and 6 using a variable water permeability tester based on JIS A 1218: 2009, the water permeability coefficient was 1 × 10 ⁻⁷ to 1 × 10 ^{− as} shown in Table 2. ^{It was 8} cm / s, and it was confirmed that the water shielding performance as an underground continuous water blocking wall was sufficiently satisfied.

DESCRIPTION OF SYMBOLS 1 Underground continuous wall construction machine 2 Bubble mixing soil 3 Wall-forming composition 4 Kneading machine 5 Tremy 6 Wall-making composition input 7 Spiral auger 8 Power machine

Claims (12)

Drilling, mixing, and mixing process, and after completion of the drilling and mixing process, the wall-forming composition is sent to the bottom of the drilling, An underground continuous water barrier method comprising a wall-forming composition replacement step, in which a bubble mixing soil is adjusted to a wet density of 1.03 to 1.72 g / cm ³ during excavation and mixing. It is soil, and the wall-forming composition used for the substitution step is a wall-forming composition obtained by kneading smectite clay mineral granules and water or smectite clay mineral granules, water and bubbles. Water barrier construction method.   A wall-forming composition prepared by mixing a foam-mixed soil adjusted in wet density with a smectite-based clay mineral granular material and water, or a wall-forming composition kneaded with smectite-based clay mineral granular material, water and bubbles during excavation and mixing. The underground continuous water blocking wall construction method according to claim 1, wherein:   The smectite clay mineral granules are immersed in a water-soluble resin having a concentration of 1 to 10%, dried, and smectite clay mineral granules whose surfaces are coated with the water-soluble resin are used. The underground continuous water barrier construction method according to 2.   The underground smectite-based clay according to claim 1 or 2, wherein the smectite-based clay mineral particles are dipped in cement milk, dried, and the surface thereof is coated with cement aggregates. Water barrier construction method.   The smectite clay mineral particles are used, wherein the smectite clay mineral particles are immersed in sodium oxalate having a concentration of 70 to 100% and dried, and the surface thereof is coated with solidified sodium oxalate. The underground continuous water barrier construction method according to 1 or 2.   3. The underground continuous stop according to claim 1, wherein the smectite clay mineral particles are immersed in an oil and fat solution and dried, and the smectite clay mineral particles whose surface is coated with the oil and fat body are used. Water wall construction method.   Claims characterized by using a wall-forming composition having a dry density increased by adjusting the particle size composition by adding any combination of clay, silt, sand, gravel and fly ash to the smectite clay mineral granules. The underground continuous water blocking wall construction method according to any one of Items 1 to 6.   The smectite clay mineral granule is a smectite clay mineral granule obtained by crushing raw ore or granulating from powder and adjusting the water content ratio and particle size. The underground continuous water barrier construction method according to one item.   The underground continuous water blocking wall construction method according to any one of claims 1 to 8, wherein a solidifying material is added to the wall-forming composition.   10. The structure according to claim 1, wherein a member that reinforces the structure is inserted into the wall-forming composition while the wall-forming composition is unconsolidated to increase the strength of the underground continuous water blocking wall. The underground continuous water barrier construction method according to any one of the above.   As a means of replacing the bubble-mixed soil and the wall-forming composition by sending the wall-forming composition to the bottom of the excavation, the wall-forming composition is sent to the bottom of the bubble-digging earth by treme and replaced using the specific gravity difference between them. The underground continuous water blocking wall construction method according to any one of the above first to tenth features As a means of replacing the bubble-mixing soil and the wall-forming composition by feeding the wall-forming composition to the bottom of excavation, the wall-forming composition is forcibly rotated by the rotation of the spiral auger. The underground continuous water blocking wall construction method according to any one of claims 1 to 10, wherein the underground discharge wall is discharged and replaced.