JP2015063669A - Composition for foundation digging/pouring material, foundation digging/pouring material, and operation method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for foundation digging/pouring material, in an original position mixing/stirring process and a soil pressure shield process, imparting a function of enabling a safe and smooth operation by mixing with digging earth upon digging, and the original position mixing/stirring process and the soil pressure shield process increasing the durability of bubbles to de-bubbling when the composition for the foundation digging/pouring material is bubbled and using the same as the foundation digging/pouring material.SOLUTION: Provided is a composition for a foundation digging/pouring material mixed with water, a dispersion liquid of a high water absorbing polymer swelled by being absorbed with the water and an air bubble agent. The high water absorbing polymer is at least one kind selected from starch series, cellulose series and synthetic polymer series and has a cross-linking structure where the water is not released by pressurization, and the funnel viscosity of the composition is 19 to 60 seconds.

Description

  The present invention relates to a composition for ground excavation injection material and a ground excavation injection material used in a method of excavating the ground vertically or horizontally in a groove shape or a cylindrical shape, and a construction method using the same.

  In the soil cement underground continuous wall method, deep ground improvement method, and earth pressure shield method, the ground is excavated in the shape of a groove or a column, and the excavation direction is vertical or horizontal. Among these methods, the soil cement underground continuous wall method and the deep ground improvement method are called in-situ mixed agitation methods because the excavated soil and the solidified material are mixed and solidified in-situ.

  In the in-situ mixed agitation method, excavation is performed while adding ground excavation injecting material to the excavated soil, a mixed soil of excavated soil and ground excavating injecting material is created, and solidified material is added to this mixed soil to mix and knead A soil cement wall is constructed, and a core material is inserted into the soil cement wall to construct a soil cement underground continuous wall.

  The ground excavation injection material is used to add functions for smooth construction such as the stability of the groove wall, the mixing with the solidified material and the fluidity for inserting the core material into the excavated soil. ing. However, if a large amount of ground excavation injection material is used, the amount of waste mud that is equal to the injection amount is generated. Therefore, in order to reduce the environmental burden, the amount of ground excavation injection material should be small and inexpensive. It has been demanded.

  On the other hand, in the earth pressure shield method, ground excavation injecting material is added to the face, and the excavated soil and ground excavation injecting material are mixed and kneaded in the face and chamber, and discharged by a screw conveyor. The ground excavation injecting material in this case is used for imparting stability of the face, fluidity for mud discharge, and water stoppage to the excavated soil. In order to reduce the environmental load, the ground excavation injection material used in the earth pressure shield method is required to satisfy these functions with a small injection amount and to be inexpensive.

  In addition, when the mixed soil obtained by mixing and kneading the excavated soil and the ground excavation injecting material has functions such as stability of the groove wall and face and fluidity sufficient for construction, it is referred to as a stabilizing liquid.

  Conventionally, in the in-situ mixing agitation method, there are many cases in which cement milk is used as a ground excavation injection material. However, if mixed soil of excavated soil and cement milk is used as a stabilizing liquid, cement milk will solidify over a long period of time, such as when there are obstacles during excavation or when the excavation depth is deep and it takes a long excavation time. . Further, in order to improve the mixing property of the cement milk mixed soil, it is necessary to increase the water-cement ratio of the cement milk to 200 to 350% and add water having a volume of about 6 to 11 times the cement volume. As a result, the amount of mud soil increased, the environmental load was large, and there were problems with the economy.

  In order to reduce these problems, the present inventor has so far proposed a method of using bubbles (see, for example, Patent Documents 1 and 2). According to these proposed methods using air bubbles, the air bubbles mixed soil mixed and kneaded with the appropriate amount of air bubbles and water depending on the soil quality of the excavated soil is suspended without causing separation of the excavated soil, air bubbles and water. (Hereinafter referred to as bubble stabilizer), and this bubble stabilizer is excellent in the stability and fluidity of the groove wall, and the amount of mud is reduced, so it is used in the in-situ mixing stirring method and shield method. Yes.

  Since the bubble stabilizing liquid is non-solidifying, it has the advantage of being able to be constructed without being restricted by time even in deep construction, and when bubbles are mixed with excavated soil, the amount of water added can be reduced due to the bearing effect, Furthermore, since the added bubbles can be defoamed with an antifoaming agent, the amount of mud soil is reduced to 1/2 to 1/3, depending on the soil quality, compared to the case of using cement milk, and the environmental load is also reduced. Smaller and more economical. Thus, since it has the outstanding workability | operativity, environmental property, and economical efficiency, the use track record of the bubble stabilizer is increasing.

  However, the bubbles currently used are originally developed for cement products such as lightweight mortar, and have not been developed for soils having various physical properties. For this reason, there is still room for improvement in terms of defoaming properties and the like.

  Usually, the durability of the bubbles mixed with concrete against defoaming is several hours, but the bubbles mixed with excavated soil need durability on a daily basis. In addition, since bubbles in excavated soil are exposed to water when the flow rate of groundwater is high or when there is pressurized groundwater, higher defoaming resistance is required.

Japanese Patent No. 3725750 Japanese Patent No. 4970547

  In the in-situ mixed stirring method and earth pressure shield method from the background as described above, the present invention provides a composition for ground excavation injecting material that gives a function of mixing with excavated soil during excavation and enabling safe and safe construction, and It is an object of the present invention to provide an in-situ mixed stirring method and an earth pressure shield method for enhancing the durability against defoaming of bubbles generated by foaming the composition for ground excavation injection material, and using this as a ground excavation injection material To do.

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

  1stly, it is the composition for ground excavation injection materials characterized by mixing water, the dispersion of the superabsorbent polymer swollen by absorbing water, and the foaming agent.

  2ndly, in the composition for ground excavation injection material of said 1st invention, it is preferable that the funnel viscosity of the said composition for ground excavation injection material is 19 to 60 seconds.

  Thirdly, in the ground excavation injecting composition of the first or second invention, the superabsorbent polymer is preferably at least one selected from starch, cellulose and synthetic polymer.

  Fourthly, in the composition for ground excavation injecting material according to the first to third aspects of the invention, the superabsorbent polymer swollen by absorbing water is a superabsorbent polymer having a crosslinked structure in which water is not released by pressurization. It is preferable that

  Fifth, in the compositions for ground excavation injection material according to the first to fourth inventions, it is preferable that the particle diameter after swelling of the superabsorbent polymer swollen by absorbing water is 3 mm or less.

  Sixth, in the composition for ground excavation injecting material of the first to fifth inventions, the foaming agent is at least one selected from a synthetic surfactant system, a resin soap system, and a hydrolyzed protein system. It is preferable.

  Seventhly, in the composition for ground excavation injection material according to the first to sixth inventions, it is preferable that a thickener is added to the composition for ground excavation injection material.

  Eighth, in the composition for ground excavation injection material of the first to seventh inventions, it is preferable that a stabilizer is added to the composition for ground excavation injection material.

  Ninthly, in the composition for ground excavation injection material according to the eighth aspect of the present invention, it is preferable that the stabilizer decreases the electrolyte concentration.

  Tenth, in the composition for ground excavation injection material according to the eighth or ninth invention, the stabilizer is preferably a neutralizing agent that neutralizes PH (hydrogen ion index concentration).

  Eleventh, in the composition for ground excavation injecting material according to the eighth to tenth inventions, the stabilizer is polyacrylamide, dilute sulfuric acid, aluminum sulfate, aluminum hydroxide, magnesium hydroxide, polyvinyl alcohol, sodium acrylate , Preferably at least one selected from polyethylene oxide, bicarbonate and carbonate.

  12thly, it is the ground excavation injection material characterized by making the composition for ground excavation injection material of the said 1st-11th invention foamed.

  13thly, it is the ground excavation injection material characterized by mixing water, the dispersion liquid of the superabsorbent polymer which absorbed water and swollen, and air bubbles.

  14thly, the ground excavation injection material of said 13th invention WHEREIN: It is preferable that the said super absorbent polymer is at least 1 type chosen from a starch type, a cellulose type, and a synthetic polymer type | system | group.

  Fifteenth, in the ground excavation / injection material of the thirteenth or fourteenth aspect, the superabsorbent polymer swollen by absorbing water is a superabsorbent polymer having a crosslinked structure that does not release water by pressurization. Is preferred.

  Sixteenthly, in the ground excavation injection material of the thirteenth to fifteenth inventions, it is preferable that the particle diameter after swelling of the superabsorbent polymer swollen by absorbing water is 3 mm or less.

  Seventeenth, there is provided a ground excavation injection material, wherein the ground excavation injection material of the twelfth invention and the ground excavation injection material of the thirteenth to sixteenth inventions are mixed.

  Eighteenth, by adding and kneading a solidifying material or a solidifying material and an antifoaming agent to a mixture obtained by adding and kneading the ground excavating injection material according to the twelfth to seventeenth aspects of the present invention to excavated soil, an in-situ mixed stirring method It is a construction method characterized by building soil cement underground continuous walls or columnar ground improvement piles.

  Nineteenth, the ground excavation injecting material of the twelfth to seventeenth aspects of the invention is injected into the face of a shield machine and kneaded with excavated soil, maintaining the stability of the face and facilitating drainage. It is a construction method to do.

  According to the present invention, in the in-situ mixing agitation method and earth pressure shield method, a composition for ground excavation injecting material which gives a function of mixing with excavated soil during excavation and enabling a safe and smooth construction, and the ground excavation It is possible to provide an in-situ mixed stirring method and an earth pressure shield method in which durability against defoaming of bubbles generated from the composition for injecting material is increased, and this is used as a ground excavation injecting material.

It is a graph which shows the relationship of the swelling polymer dispersion liquid concentration and the funnel viscosity of the liquid mixture of a swelling polymer dispersion liquid and a foaming agent. It is a graph which shows the relationship between the density | concentration of a swelling polymer dispersion, and the viscosity of a polymer bubble (viscosity of the liquid mixture containing a polymer bubble). It is a graph which shows the relationship between the density | concentration of the swelling polymer dispersion which influences the viscosity of a polymer bubble, and the dilution rate of a foaming agent. It is a graph which shows the relationship between the density | concentration of a swelling polymer dispersion, and the defoaming rate of a polymer bubble. It is a graph which shows the density | concentration of a swelling polymer dispersion, and the relationship between vane shear strength. It is a graph which shows the relationship between the addition amount of a polymer bubble and the applied pressure which affect the volume change rate of a bubble stabilizer. It is a graph which shows the relationship of the change of the viscosity by the weight mixing ratio of a polymer bubble and a swelling polymer dispersion liquid. It is a graph which shows the relationship of the defoaming rate of the bubble of a polymer bubble mixture with progress of time.

  The composition for ground excavation injection material according to the present invention is a mixture of water, a superabsorbent polymer dispersion (hereinafter referred to as a swollen polymer dispersion) swollen by absorbing water, and a foaming agent. is there. And in use, the bubble (henceforth a polymer bubble) which foamed the liquid mixture which mixed these is used as a ground excavation injection material.

  Since the composition for ground excavation injection material of the present invention is usually used from the ground surface to a large depth, for example, the amount of water separation is small even under a stable hydraulic pressure at a large depth of 100 m, and the bridge is not easily deformed. It is necessary to select superabsorbent polymer particles having a structure, and in order to clog the gaps between soil particles in the soil layer where mud is likely to occur, the particle size after swelling has a particle size distribution of 3 mm or less. Things are desirable.

  As the superabsorbent polymer used in the present invention, any superabsorbent polymer that satisfies the above-mentioned conditions can be used without particular limitation, but sodium acrylate superabsorbent polymer particles can be suitably used. What adjusted the sodium acrylate superabsorbent polymer particle of the double structure of a shell and a core to said conditions can be used suitably.

  The above superabsorbent polymer particles are hydrophilic superabsorbent polymers having a cross-linked structure, have a water absorption of 10 times or more of their own weight, and are difficult to separate even under pressure. Is defined in JIS K 7223.

  The type of superabsorbent polymer particles used in the present invention can be used without particular limitation as long as the water separation due to pressure is small and the particle size after swelling is 3 mm or less. For example, starch-based, cellulose-based, synthetic polymer-based Can be mentioned. Among these, synthetic polymer-based sodium acrylate superabsorbent polymer particles can be particularly preferably used in terms of both performance and cost.

Sodium acrylate superabsorbent polymer particles are a gel of acrylic acid polymer partial sodium salt cross-linked product having a three-dimensional network structure that is lightly cross-linked by adding a cross-linking agent to sodium acrylate (CH ₂ = CH-COONa). It is. There are various types of crosslinking agents.

  It is known that the sodium acrylate superabsorbent polymer particles, when absorbing water, dissociate sodium ions into the gel when it absorbs water, and if pure water produces a degree of swelling that is 100 to 1000 times its own weight. .

  In addition, the water absorption of the sodium acrylate highly water-absorbing polymer particles is such that if a large amount of a crosslinking agent is added to sodium acrylate, the gel becomes hard and the water absorption decreases. Further, when the amount of the crosslinking agent is decreased, the gel becomes soft and the water absorption amount increases.

  Furthermore, as a special sodium acrylate superabsorbent polymer particle, there is a sodium acrylate superabsorbent polymer particle having a shell-core dual structure, in which the surface of the superabsorbent polymer particle polymerized with a crosslinking agent is further crosslinked. is there.

  In the case of the sodium acrylate highly water-absorbing polymer particles having a dual structure of shell and core, the thicker the shell, the harder the gel and the smaller the water absorption. The thinner the shell, the softer the gel and the greater the water absorption.

  The above shell and core are usually crosslinked by an ester bond, but there are also sodium acrylate superabsorbent polymer particles in which the core bond is an ether bond excellent in alkali resistance and electrolyte resistance. In the invention, this ether bond is more preferable.

  In addition to the above properties, dissociation of sodium ions in sodium acrylate superabsorbent polymer particles also depends on conditions such as pH and salt concentration where the gel is placed, so other superabsorbent polymer particles depending on the use conditions Can be appropriately selected and used in combination.

  As the foaming agent used in the composition for ground excavation injecting material of the present invention, a synthetic surfactant system, a resin soap system and a hydrolyzed protein system can be used without particular limitation. Among these, alkyl sulfate-based synthetic surfactants having a high bubble ratio and high alkali resistance of cement can be suitably used.

  The weight blending ratio of the swelling polymer dispersion and the foaming agent is not particularly limited as long as foaming can be performed at a predetermined magnification. However, from the viewpoint of easiness of foaming, etc., a mixed liquid in which the swelling polymer dispersion and the foaming agent are mixed. Those having a funnel viscosity adjusted to 19 to 60 seconds can be particularly preferably used. The funnel viscosity of the mixed liquid can be easily adjusted by appropriately setting the concentration of the swollen polymer dispersion.

  Here, the funnel viscosity is a viscosity measured using a Marsh Funnel viscometer that measures the viscosity according to the outflow time (seconds) required for discharging 500 ml of the sample liquid placed in a 500 ml funnel-shaped container.

  A method of creating a polymer bubble by foaming a composition for ground excavation injection material of a mixture of a swelling polymer dispersion and a foaming agent can be appropriately selected in view of the situation at the site, for example, swelling polymer dispersion It is also possible to foam a polymer bubble by feeding a mixed solution obtained by mixing a liquid and a foaming agent and compressed air to a foaming generator to foam the polymer bubbles, or by mixing and stirring with a mixer.

  When polymer bubbles are used as the ground excavation injection material, durability against defoaming of the polymer bubbles per se is required, and durability against defoaming with a bubble stable liquid mixed with excavated soil is also required.

  The viscosity of the polymer bubbles can be easily adjusted by adjusting the concentration of the swelling polymer dispersion. By increasing the viscosity of the polymer bubbles, it is possible to reduce the effects of evaporation of the polymer bubbles from the bubble film, gravity and plateau boundaries, and the bubble film becomes thinner and cannot withstand internal pressure. The durability against defoaming can be increased.

  The durability of the polymer bubbles was confirmed by the following experiment. In this experiment, a swollen polymer dispersion in which a highly water-absorbing polymer (manufactured by Sanyo Chemical Industries, Ltd .: GEOSAP) was mixed with water and sufficiently absorbed, and a foaming agent (manufactured by Floric: water of WTM foaming agent stock solution). Diluted solution) was used. The dilution ratio of the foaming agent was the weight ratio of the swollen polymer dispersion of the WTM foaming agent stock solution to water.

  The mixture of the swollen polymer dispersion and the foaming agent was prepared by adding a superabsorbent polymer in an amount to obtain a predetermined concentration in water, and then adding and mixing a WTM foaming agent stock solution in an amount to obtain a predetermined dilution ratio. In the subsequent experiments, mixing was performed in the same order.

  The concentration of the swollen polymer dispersion is 0% to 0.6%, the foaming agent is diluted 80 times the WTM foaming agent stock solution, and the relationship between the funnel viscosity of these liquid mixtures and the concentration of the swollen polymer dispersion and the liquid mixture The relationship between the viscosity of the foamed polymer bubbles (viscosity of the mixed liquid containing polymer bubbles) and the concentration of the swollen polymer dispersion was examined. The results are shown in Table 1, FIG. 1 and FIG.

  According to Table 1 and FIG. 1, the funnel viscosity of the mixture of the swollen polymer dispersion and the foaming agent increases rapidly as the concentration of the swollen polymer dispersion increases and the concentration of the swollen polymer dispersion is 0% (only the foaming agent). ) Is approximately 3.2 times at 0.3%. In addition, it was impossible to measure with a Marsh funnel viscometer at 0.4 to 0.6%, but foaming was possible at 0.4 to 0.5%. From this, it was confirmed that the funnel viscosity of the mixed solution can be easily adjusted largely by increasing the concentration of the swollen polymer dispersion.

  In FIG. 2 showing the relationship between the concentration of the swollen polymer dispersion and the viscosity of the polymer bubbles obtained by foaming the mixed liquid 25 times (the viscosity of the mixed liquid containing the polymer bubbles), the swollen polymer dispersion concentration is 0% (foaming). Viscosity is about 1.7 times that of 0.5%. From this, it was confirmed that the viscosity of the polymer bubbles (viscosity of the mixed solution containing polymer bubbles) can be easily adjusted by increasing the concentration of the swollen polymer dispersion.

  Next, the viscosity of the polymer bubbles was examined when the concentration of the swelling polymer dispersion and the dilution ratio of the foaming agent were changed. The concentration of the swelling polymer dispersion was 0%, 0.2%, and 0.4%, and the dilution ratio of the foaming agent was 20% to 100%. . The viscosity of the bubbles is shown in FIG.

  According to FIG. 3, the viscosity of the bubbles tends to gradually decrease as the dilution factor increases. However, it was confirmed that when the concentration of the swollen polymer dispersion was increased regardless of the dilution ratio, the viscosity of the bubbles increased, and the influence of the swollen polymer dispersion concentration on the viscosity of the polymer bubbles was large.

  Next, the defoaming property of the bubble by the presence or absence of addition of the swelling polymer dispersion was examined. The concentration of the swelling polymer dispersion was 0% (no addition) and 0.2%, the dilution ratio of the foaming agent was 60 times, and the mixture of the swelling polymer dispersion and the foaming agent was foamed 25 times each. Air bubbles were used. The defoaming rate was the percentage of the separated foaming agent weight (the defoamed and separated foaming agent weight) and the foaming agent weight. The experimental results are shown in FIG.

  According to FIG. 4, it can be seen that the defoaming rate is clearly smaller in the polymer bubbles to which the 0.2% concentration of the swollen polymer dispersion was added.

  From this, it was confirmed that the effect of the concentration of the swollen polymer dispersion was large in order to increase the durability of the bubbles themselves against defoaming.

  Next, the following experiment was carried out on the durability of the bubble stabilizing liquid in which excavated soil, polymer bubbles and water were mixed. As the excavated soil, dredged sand No. 5 was used, and the bubbles mixed with the excavated soil were generated in the foam produced by diluting the foaming agent stock solution 40 times and foamed 25 times, and the 0.2% concentration swelling polymer dispersion. A liquid mixture was prepared by adding the foaming agent stock solution at a dilution ratio of 80 times, and polymer bubbles were used which were foamed 25 times. These two types of bubbles were mixed with silica sand No. 5 having a water content of 8.0% in a volume ratio of 42% to prepare a bubble stabilizing solution.

  Assuming the state in the soil, these bubble stabilizers were filled up to 1000 ml of a graduated cylinder with an inner diameter of 63 mm and a height of 432 mm, the mouth was covered with a rubber cap, the outside air was shut off, and stored in a constant temperature room at 20 degrees. In the measurement, the amount of settlement on the top surface of the bubble stabilizing liquid is visually measured with a graduated cylinder, and the vane shear strength at a position 300 mm from the top surface is estimated using a vane tester in order to estimate the state of bubbles in the bubble stabilizing liquid. Was measured.

  Even after 14 days from the preparation of the sample, neither of these two types of bubble stabilizers showed surface subsidence, and no separation of the bubble stabilizers.

Furthermore, the relationship between the passage of time and the vane shear strength in the bubble stabilizing liquid is shown in FIG. According to FIG. 5, even after 14 days had elapsed, both vane shear strengths maintained high fluidity of about 0.2 to 0.3 kN / m ² .

  Considering that the 40-fold diluted air bubbles used in the test are currently used in construction, mixing the 0.2% concentration of the swelling polymer dispersion and the 80-fold diluted foaming agent It was found that the polymer bubbles obtained by foaming the liquid 25 times can be used in the same manner as the current bubbles.

  Furthermore, the actual excavation work can be completed within a few hours to 2 days. However, if polymer bubbles are used, high fluidity will be maintained for at least 14 days. Even if it was impossible, it was found that there was enough time to resume construction.

  Next, in consideration of the use of the bubble stabilizing liquid from a shallow depth to a large depth, an experiment was conducted on bubble breakage in the bubble stabilizing liquid.

  Using dredged sand No. 5 as excavated soil, make a mixed solution by adding the foaming agent stock solution to the 0.2% concentration swelling polymer dispersion so that the dilution factor is 80 times, and foam this 25 times Polymer bubbles were used. The polymer bubbles were mixed with silica sand No. 5 having a water content of 8.0% at a volume ratio of 28%, 44%, and 54%, respectively, to prepare a bubble stabilizing solution.

  This bubble stabilizing solution was packed in an acrylic cylinder having an inner diameter of 106 mm and a height of 400 mm to a height of 250 mm, pressurized and depressurized with a steel piston from above, and the amount of compression was measured by the change in height. When the volume change rate of the bubble stabilizing liquid is expressed by (original height of the bubble stabilizing liquid−compressed height) / original height of the bubble stabilizing liquid × 100, the relationship between the applied pressure and the volume change rate is shown in FIG. It became as follows.

  From this result, the volume change rate increases as the mixing amount of polymer bubbles increases. However, the volume change rate becomes almost 0% when the pressure is reduced regardless of the bubble amount. It turns out that it doesn't break.

  From the above results, it was confirmed that the bubble stabilizer prepared by mixing polymer bubbles in excavated soil can maintain the physical properties necessary for excavation for at least 14 days. In addition, it was confirmed that the bubbles did not break even when the loading pressure varied, and that the pressure variation was sufficiently compatible. Note that the foaming agent used for the polymer bubbles has a dilution ratio of 80 times, which is obtained by further diluting the normal dilution ratio of 20 times or 40 times to 2 to 4 times. It was confirmed to be excellent.

  On the other hand, in excavation work using polymer bubbles in which the composition for ground excavation injecting material of the present invention is foamed, when excavating a rough gravel layer or a pressurized groundwater layer in which the flow of groundwater is fast, the bubble film is converted into groundwater. It becomes easy to defoam because it is exposed. In such a case, bubbles or polymer bubbles are mixed with the swollen polymer dispersion, so that the bubbles are surrounded by a swollen superabsorbent polymer to reduce the degree of dilution of the bubble membrane with water, thereby preventing defoaming. Therefore, a ground excavation injection material that enables more stable construction can be used.

  Specifically, a ground excavation injection material in which bubbles or polymer bubbles and a swelling polymer dispersion are mixed with a mixer such as a mixer is used. The volume mixing ratio of the bubbles and the swollen polymer dispersion can be used without particular limitation as long as they can be mixed, but the funnel viscosity of the swollen polymer dispersion is preferably 60 seconds or less.

  In order to confirm this, the following experiment was conducted. Into the polymer bubbles in which 0.2% of the swollen polymer dispersion and a foaming agent diluted 80 times were foamed 25 times, the swollen polymer dispersions having a concentration of 0.3% and 0.4% were added in volume. Mixing was performed at a mixing rate (percentage of swelling polymer dispersion volume to polymer bubble volume) of 0 to 100%, and the viscosity of the polymer bubbles was measured. The result is shown in FIG.

  According to FIG. 7, it was confirmed that the viscosity of the polymer bubbles was proportional to the concentration of the swollen polymer dispersion rather than the volume mixing ratio.

  Next, assuming a state where the bubble stabilizing liquid is in contact with the flowing groundwater, the defoaming rate of the bubbles in the bubble stabilizing liquid was determined as follows.

  Saturated dredged sand No. 5 was assumed as excavated soil for excavation. As a ground excavation injecting material, a 0.2% swelled polymer dispersion in a volume ratio of 0.2% swollen polymer dispersion mixed with a foaming agent diluted 60 times is foamed 25 times. An equal volume mixed polymer foam mixture was used. The mixing ratio of the silica sand No. 5 in the saturated state and the polymer bubble mixture was mixed at a volume ratio of 1: 0.3 with reference to the mixing ratio not separated from the theory of the bubble stabilizer, and this was used as the bubble stabilizer.

  1000 ml of this bubble stabilizer was filled in an acrylic cylinder having a diameter of 63 mm, and water was sprinkled over the bubble stabilizer to the mouth, and the amount of decrease in the height of the bubble stabilizer was measured. Then, the amount of reduction in the height of the bubble stabilizing liquid was considered as the amount of bubbles removed, and the bubble removal rate was determined.

  The relationship between the elapsed time and the bubble defoaming rate is shown in FIG. According to FIG. 8, in the stabilizing solution using unused bubbles of the swelling polymer dispersion, the bubbles disappeared or separated by the water on the upper surface, and after about 48%, the bubbles disappeared about 48%. Only about 22% of the bubbles to which the liquid was added were defoamed, and the viscosity of the bubbles was almost the same, but the defoaming rate was significantly reduced.

  From this, it was confirmed that the defoaming rate due to the pressured groundwater decreases when the mixture obtained by adding the swelling polymer dispersion to the polymer bubbles is used as the ground excavation injection material.

  Moreover, a thickener can be added to the composition for ground excavation injection material of this invention in order to make a polymer bubble more stable. Specifically, polyville alcohol (PVA) can be suitably used.

  In addition, in the composition for ground excavation injection material of the present invention, when an electrolyte such as salt in the ground or an acidic or alkaline substance is mixed, the property and quality of the composition for ground excavation injection material can be suppressed. Stabilizers can be added to allow recovery. Specifically, it has a function as a neutralizing agent that neutralizes PH (hydrogen ion exponential concentration).

  Examples of the stabilizer used in the present invention include polyacrylamide, dilute sulfuric acid, aluminum sulfate, aluminum hydroxide, magnesium hydroxide, polyvinyl alcohol, sodium acrylate, polyethylene oxide, sodium hydrogen carbonate, calcium hydrogen carbonate, potassium hydrogen carbonate. Further, at least one selected from hydrogen carbonates such as ammonium hydrogen carbonate and carbonates such as sodium carbonate, calcium carbonate, potassium carbonate, and ammonium carbonate can be used.

  In the construction process, electrolytes such as salinity were mixed in the ground excavation injection composition, and when the electrolyte concentration increased, the water absorption ratio of the superabsorbent polymer particles of the ground excavation injection composition decreased and absorbed water. By releasing moisture, the funnel viscosity of the ground excavation additive composition deteriorates.

  In such a situation, by adding a stabilizer in advance, an increase in the electrolyte concentration can be suppressed and deterioration of the composition for ground excavation injection material can be prevented.

  The ground excavation injection material of the present invention can be particularly suitably used for the in-situ mixing stirring method and the earth pressure shield method.

  When constructing soil cement underground continuous walls and columnar soil improvement piles by in-situ mixed agitation method, excavation is performed by discharging the ground excavation injection material of the present invention to the excavation part of each construction machine, and excavation soil and ground Mixing and stirring the excavation injection material, adding the solidification material or solidification material and antifoaming agent to this mixed soil, mixing and kneading, it is possible to construct a soil cement wall and a columnar ground improved pile.

  The construction machine can be used regardless of the construction machine, such as a constant-thickness type (cutter chain stirring method), a columnar row type (auger stirring method), or a horizontal multi-axis type. Furthermore, what mixed water and cement milk with this ground excavation injection material can also be used at the time of excavation.

  In addition, when constructing the earth pressure shield method, excavation is carried out while injecting the ground excavation injection material of the present invention into the face, and the excavation soil and ground excavation injection material are mixed and agitated. Aqueous properties can be imparted. In particular, in order to prevent the face from collapsing, it can be suitably used in a construction in which a pressure higher than the collapse pressure is applied to the mixed soil in the face and the chamber and the soil is discharged from the screw conveyor. The pressure in the face and the chamber and the amount of waste soil from the screw conveyor can be adjusted by the excavation speed, the rotational speed of the screw conveyor, the amount of ground excavation injection material added, and the like.

Claims (19)

  A composition for ground excavation injection material, wherein water, a dispersion of a superabsorbent polymer swollen by absorbing water, and a foaming agent are mixed.   The funnel viscosity of the composition for ground excavation injection material is 19 to 60 seconds, The composition for ground excavation injection material of Claim 1 characterized by the above-mentioned.   The composition for ground excavation injection material according to claim 1 or 2, wherein the superabsorbent polymer is at least one selected from starch, cellulose and synthetic polymer.   The ground excavation according to any one of claims 1 to 3, wherein the superabsorbent polymer swollen by absorbing water is a superabsorbent polymer having a crosslinked structure that does not release water by pressurization. Composition for injection material.   The composition for ground excavation injection material according to any one of claims 1 to 4, wherein a particle size after swelling of the superabsorbent polymer swollen by absorbing water is 3 mm or less.   The ground foaming injection material according to any one of claims 1 to 5, wherein the foaming agent is at least one selected from a synthetic surfactant system, a resin soap system, and a hydrolyzed protein system. Composition.   The composition for ground excavation injection materials according to any one of claims 1 to 6, wherein a thickener is added to the composition for ground excavation injection materials.   The composition for ground excavation injection material according to any one of claims 1 to 7, wherein a stabilizer is added to the composition for ground excavation injection material.   The composition for ground excavation injection material according to claim 8, wherein the stabilizer is a stabilizer that lowers an electrolyte concentration.   The composition for ground excavation injection material according to claim 8 or 9, wherein the stabilizer is a neutralizing agent for neutralizing PH (hydrogen ion index concentration).   The stabilizer is at least one selected from polyacrylamide, dilute sulfuric acid, aluminum sulfate, aluminum hydroxide, magnesium hydroxide, polyvinyl alcohol, sodium acrylate, polyethylene oxide, bicarbonate, carbonate. The composition for ground excavation injection material as described in any one of Claims 8 to 10.   An injecting material for ground excavation, wherein the composition for injecting ground excavation according to any one of claims 1 to 11 is foamed.   A ground excavation injection material comprising water, a dispersion of a superabsorbent polymer that has absorbed water and swollen, and bubbles.   The ground excavation injection material according to claim 13, wherein the superabsorbent polymer is at least one selected from starch, cellulose and synthetic polymer.   The ground excavation injection material according to claim 13 or 14, wherein the superabsorbent polymer swollen by absorbing water is a superabsorbent polymer having a crosslinked structure that does not release water by pressurization.   The ground excavation injection material according to any one of claims 13 to 15, wherein a particle diameter after swelling of the superabsorbent polymer swollen by absorbing water is 3 mm or less.   A ground excavation injection material according to claim 12, wherein the ground excavation injection material according to any one of claims 13 to 16 is mixed.   A solidified material or a solidified material and an antifoaming agent are added and kneaded to a mixture obtained by adding and kneading the ground excavating material according to any one of claims 12 to 17 to excavated soil, and in-situ mixed stirring Construction method characterized by constructing soil cement underground continuous wall or columnar ground improved pile by construction method.   The ground excavation material according to any one of claims 12 to 17 is injected into a face of a shield machine and kneaded with excavated soil to maintain stability of the face and facilitate drainage. The construction method.

Images