JP7307650B2 - Cutting composition and high-pressure injection stirring method using the same - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law (1) The 74th Annual Academic Lecture of the Japan Society of Civil Engineers 2019 [Lecture Summaries] DVD-ROM (Issue date: August 1, 2019) announced. (2) The 74th Annual Academic Lecture of the 2019 Japan Society of Civil Engineers National Convention “Development of a high-pressure injection stirring method with improved cutting efficiency (1)-Verification of the effect of superabsorbent polymer water injection by air injection test- ” (Lecture No. VI-678). (3) 2019 74th Annual Academic Lecture of the Japan Society of Civil Engineers National Convention "Development of high-pressure injection stirring method with improved cutting efficiency (2)-Verification of the effect of superabsorbent polymer water injection by air injection test- ” (Lecture No. VI-679).

TECHNICAL FIELD The present invention relates to a cutting composition and a high-pressure injection stirring method using the same.

2. Description of the Related Art Conventionally, as a method for cutting an object, there has been known a cutting method using a water jet, in which high-pressure water is jetted from the tip of a small-diameter nozzle to cut the object. In this way, there are a wide variety of applications for cutting things with a water jet. It is widely used for construction excavation, cutting of underwater structures, etc. (see, for example, Patent Documents 1 and 2).

Further, in order to improve cutting performance in cutting by the water jet, various studies have been conventionally made (Non-Patent Document 1). According to this research, the flow velocity distribution conceptual diagram shown in Fig. 1 was clarified as a structural model of water jet flow by high-pressure injection. It is said that it is important to take

On the other hand, a high-pressure injection stirring method is known as one of ground improvement methods using a water jet cutting method (see, for example, Patent Document 3). In this high-pressure injection agitation method, a rod having an injection hole is erected in the ground, and the solidifying material is injected from the injection hole at high pressure while rotating the rod to cut the ground and stir and mix the soil particles and the cement-based solidifying material. It is a construction method that creates an improved body by solidifying it with a small machine, and it has a wide range of uses because it can create a large diameter and high strength improved body.

However, in the above-mentioned high-pressure injection agitation method, a large amount of sludge with a high water content containing cement-based solidification material is discharged during ground improvement, so in the city center where there is no aeration point, the disposal cost of sludge is expensive.

In particular, when creating a large-diameter improvement body, in addition to the injection of ultra-high pressure cement-based solidifying material, ultra-high pressure cutting water is used to scrape the ground while mixing and stirring. Mud is generated and the costs associated with industrial waste disposal are increased.

In addition, the high-pressure jet stirring method includes a method of construction without pre-cutting (pledget) and a method of construction with pre-cutting on the ground, but when cutting directly without pre-cutting, In the case of cohesive ground, gravel ground, etc., poor improvement is likely to occur due to cutting of the ground and insufficient stirring of the cement-based solidification material. It may be a factor for increasing the water content.

JP-A-10-148090 JP-A-7-186049 JP-A-2005-76211

Hiroshi Yoshida, Research on flow characteristics of water jet and improvement of its cutting performance, Doctoral dissertation, Graduate School of Osaka University, 2011

The present invention has been made in view of the above circumstances, and provides a cutting composition capable of further improving cutting efficiency in water jet cutting, and uses this cutting composition. Therefore, it is an object of the present invention to provide a high-pressure injection stirring method capable of reducing the generated high water content mud and reducing the disposal cost of industrial waste.

That is, the high-pressure injection stirring method of the present invention is characterized by the following.
First, the cutting composition of the present invention is a cutting composition that is jetted from a jet nozzle to cut an object,
The cutting composition is characterized by comprising water and an aqueous polymer solution containing a superabsorbent polymer swollen by absorbing water.
Secondly, in the cutting composition of the first invention, the aqueous polymer solution preferably contains an abrasive.
Thirdly, in the cutting composition according to the second aspect of the invention, the aqueous polymer solution containing the abrasive comprises a fluid abrasive comprising an abrasive and a water-absorbing polymer, water and highly water-absorbing water-swollen abrasives. It is preferably a mixture of an aqueous polymer solution containing a polymer.
Fourth, in the cutting composition of the second or third invention, it is preferable that the abrasive is silica sand.
Fifth, in the high-pressure injection stirring method of the present invention, a rod equipped with a cutting water injection nozzle and a solidifying material injection nozzle is inserted into the ground, and while rotating and pulling up, cutting water is injected from the cutting water injection nozzle into the ground improvement area. A ground cutting process for cutting the ground by high-pressure jetting toward
While rotating and pulling up the injection rod inserted into the ground, the solidification material and the excavated ground are stirred and mixed to solidify by injecting the solidification material from the solidification material injection nozzle at high pressure toward the ground improvement area. In the high-pressure injection stirring method having a solidification process,
The cutting fluid is characterized by using the cutting composition according to any one of the first to fourth aspects.
Sixthly, in the high-pressure jet stirring method of the fifth invention, in the ground cutting step, the ground cutting step includes a fluidized abrasive composed of an abrasive and a water-absorbent polymer, and water and a superabsorbent polymer swollen by absorbing water. It is preferable that each of the aqueous polymer solutions is fluid-pumped to the tip of the cutting water injection nozzle, mixed in the cutting water injection, and injected as the cutting water at high pressure.

According to the cutting composition of the present invention, by spraying the cutting composition containing water and an aqueous polymer solution composed of a highly water-absorbent polymer swollen by absorbing water, the cutting efficiency is higher than that of conventional water-only cutting. can be improved and the cutting time can be shortened. In addition, by using this cutting composition in the high-pressure injection stirring method, it is possible to create a large diameter, reduce the amount of cutting water injected, and reduce the volume of sludge discharged. becomes.

FIG. 3 is an explanatory diagram of a flow velocity distribution concept; BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing which shows one Embodiment of the high pressure injection stirring construction method which concerns on this invention. 1 is a schematic diagram of an injection experimental device used in Examples 1 and 2; FIG. (A) is a graph showing the relationship between the injection distance to the concrete pressure receiving plate and the maximum cutting depth, and (B) is a graph showing the measurement results of the injection distance and the amount of mass reduction due to erosion. 4 is a photograph of the surface state of a concrete pressure plate onto which tap water and a cutting composition using polymer A and polymer B have been sprayed. FIG. 10 is a jet visualization photograph taken with a backlight of a high-speed camera, showing a water jet and a jet state of a cutting composition using aqueous polymer solutions of polymer A and polymer B. FIG. FIG. 2 is a schematic cross-sectional view showing the structure of an abrasive nozzle; (A) is a graph showing the relationship between the maximum cutting depth and the injection distance in a preliminary experiment in Example 2; (B) is a graph showing the relationship between the maximum cutting depth and the injection distance in Example 2; C) is a graph showing the relationship between the amount of mass reduction and the injection distance. Tap water, polymer aqueous solution B of Example 1, and sample No. 5 is a jet visualized photograph taken by a high-speed camera with a backlight, showing the state of the jet of No. 5. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the cutting composition of the present invention and the high-pressure injection stirring method using the same will be described in detail with reference to embodiments for carrying out the present invention.

The cutting composition of the present invention is a cutting composition that is jetted from a jet nozzle to cut an object, and the cutting composition comprises water and a superabsorbent polymer swollen by absorbing water. It consists of an aqueous polymer solution containing

The superabsorbent polymer used in the cutting composition of the present invention is a hydrophilic polymer particle having a crosslinked structure, has a water absorbency of about 10 to 500 times its own weight, and absorbs water even when pressure is applied. It has the characteristic of being difficult to release. The water-absorbing action of such a water-absorbing polymer is exerted by the osmotic pressure caused by the ion concentration difference between the inside and outside of the polymer. Therefore, the electrical conductivity of the solvent to be mixed and stirred with the superabsorbent polymer can be adjusted, for example, by adding an electrolyte such as sodium chloride. ) can be changed. Water is used as the solvent, and tap water is particularly suitable for cutting.

The type of superabsorbent polymer is not particularly limited, and for example, it is preferably at least one selected from the group consisting of starch-based, cellulose-based, and synthetic polymer-based polymers.

Among the superabsorbent polymers described above, the synthetic polymer-based sodium polyacrylate superabsorbent polymer is excellent in terms of both performance and cost, and thus can be particularly preferably used.

Sodium polyacrylate superabsorbent polymer is an acrylic acid polymer partially sodium salt cross-linked product having a three-dimensional network structure, which is lightly cross-linked by adding a cross-linking agent to sodium acrylate (CH ₂ =CH-COONa). is a gel. A conventionally well-known thing can be used as a crosslinking agent.

It is known that when the sodium polyacrylate superabsorbent polymer absorbs water, the carboxyl groups dissociate sodium ions in the gel, and if pure water is used, the degree of swelling reaches 100 to 1000 times its own weight. .

Examples of such a sodium polyacrylate superabsorbent polymer include GEOSAP (registered trademark, hereinafter the same). In the case of GEOSAP, its water absorption capacity is about 450 times its own weight, and its fluidity is good when it is made into an aqueous solution of a superabsorbent polymer.

Also, in the sodium polyacrylate superabsorbent polymer, by blending a large amount of a cross-linking agent with sodium acrylate, the obtained gel becomes hard and its water absorption decreases. Also, when the amount of the cross-linking agent is reduced, the resulting gel becomes softer and its water absorption increases.

Furthermore, as a special sodium polyacrylate superabsorbent polymer, a sodium polyacrylate superabsorbent polymer having a double structure of shell and core is obtained by further cross-linking the surface of the superabsorbent polymer polymerized with a cross-linking agent. Uses are exemplified.

In the superabsorbent sodium polyacrylate polymer having a dual structure of shell and core, the thicker the shell, which is the outer shell, the harder the gel becomes and the less water it absorbs. On the other hand, if the thickness of the shell is reduced, it becomes a soft gel and its water absorption increases.

In addition, the above shell and core are usually cross-linked by ester bonds, but the cross-linked sodium polyacrylate superabsorbent polymer in which the shell and core are cross-linked by ether bonds with excellent alkali resistance and electrolyte resistance exist. In the present invention, it is more preferable to use a sodium polyacrylate superabsorbent polymer in which the shell and core are crosslinked by ether bonds.

In addition to the above characteristics, the dissociation of sodium ions in sodium polyacrylate superabsorbent polymer also depends on conditions such as pH and electrolyte concentration where the gel is placed, so other superabsorbent polymers may be used depending on the conditions of use. It can be selected and used as appropriate.

The concentration of the aqueous polymer solution in the cutting composition of the present embodiment can be appropriately adjusted according to the water absorption performance of the superabsorbent polymer, the ion concentration of the water that absorbs water, and the properties of the object to be cut.

In general, when a superabsorbent polymer with high water absorption performance is used, the viscosity tends to increase, and when a superabsorbent polymer with low water absorption performance is used, the viscosity tends to decrease. Therefore, it is desirable to set the concentration so that the aqueous polymer solution has a desired viscosity in consideration of the water absorbing performance of the water absorbing polymer used. By using the cutting composition of the present embodiment, the potential area in the flow velocity distribution conceptual diagram shown in FIG. 1 can be lengthened, and the cutting efficiency can be improved.

In the cutting composition of the present invention, an electrolyte such as sodium chloride can be added together with the aqueous polymer solution in order to adjust the water absorption rate of the water-absorbent polymer.

Furthermore, in the cutting composition of the present invention, an abrasive can be added to the aqueous polymer solution. As the abrasive, for example, sand, silica sand, garnet, etc. can be used, and among these, silica sand can be preferably used. The particle size of the abrasive is not particularly limited, but when considering the fluidity of the aqueous polymer solution to which the abrasive is added, the machinability of the abrasive, etc., the average particle diameter _D50 is in the range of 320 to 570 μm. is preferred.

Further, in the present embodiment, the abrasive-added polymer aqueous solution to which the abrasive is added may be directly injected, but the polymer aqueous solution composed of the superabsorbent polymer and water and the superabsorbent polymer that has been made to absorb water in advance may be sprayed directly. A fluid abrasive prepared by adding and mixing an abrasive may be mixed at the tip of the injection nozzle and injected. In such a mixed injection at the tip of the injection nozzle, for example, a nozzle with a double-pipe structure as shown in FIG. can be mixed and injected. As the injection nozzle having the double-tube structure, an abrasive nozzle generally used for cutting can be preferably used.

It should be noted that the highly water-absorbing polymer used in the fluid abrasive preferably has a small polymer particle size after absorbing water so as not to separate easily after adding the abrasive. Specifically, a highly absorbent polymer having a polymer particle size of about 100 μm after absorbing water can be suitably used. By using a highly water-absorbent polymer having a small polymer particle size after water absorption, a fluid abrasive in which the abrasive is uniformly dispersed can be prepared.

Moreover, the cutting composition of the present invention can be suitably used in a conventionally known high-pressure injection stirring method. The high-pressure injection stirring method according to the present invention will be specifically described below. FIG. 2 is a schematic illustration of one embodiment of the high-pressure injection stirring method according to the present invention.

In the high-pressure injection stirring method of the present invention, a rod equipped with a cutting water injection nozzle and a solidifying material injection nozzle is inserted into the ground at a predetermined depth, and cutting water is injected from the cutting water injection nozzle at high pressure toward the ground improvement area. A high-pressure injection stirring method that includes a ground cutting process in which the ground is cut by means of a high-pressure injection agitating process, and a stirring and mixing process in which the solidifying material and the excavated ground are stirred and mixed by high-pressure injection of the solidifying material from the solidifying material injection nozzle toward the ground improvement area. and the above cutting composition is used as cutting water.

(Ground cutting process)
In the high-pressure jet stirring method of the present embodiment, first, as a ground cutting step, while rotating the rod, high-pressure cutting water is jetted toward the ground improvement zone from the cutting water jetting nozzle provided at the tip of the rod. The cutting water used in the high-pressure jet stirring method of the present embodiment is a cutting composition comprising at least water and an aqueous polymer solution composed of a highly water-absorbing polymer that has swollen by absorbing water. In addition, the high-pressure injection stirring method of the present invention can be applied to the ground without pre-cutting (pledget) or after pre-cutting.

The amount of the abrasive to be supplied to the aqueous polymer solution is not particularly limited as long as the fluid can be stably pumped from the ground to the tip of the injection nozzle. 3 to 5 kg/min, preferably about 4 kg/min.

In the high-pressure injection stirring method of the present invention, by using the cutting composition of the present invention, the stability of loose ground can be secured, and highly safe advanced cutting becomes possible. In addition, since the machinability is improved, it is possible to increase the speed at which the injection is pulled up during preparation compared to conventional water-only cutting. It becomes possible to plan As a result, cutting and preparation time can be shortened, the amount of industrial waste can be reduced, shortening the construction period, and cost reduction can be expected.

Further, as the cutting composition used in the high-pressure jet stirring method of the present invention, a cutting composition obtained by adding an abrasive to the aqueous polymer solution can be used. Addition of the abrasive in the present embodiment is performed by adding the abrasive to the aqueous polymer solution, dispersing and suspending the abrasive in place of the conventional pneumatic feeding method, which is difficult to pump into the ground. Fluid can be pumped from the ground to the nozzle tip. As a result, it is possible to feed the abrasive over a long piping distance, prevent clogging in the transport pipe, and adjust and supply the amount of the abrasive in a stable manner. In addition, this fluid transport method enables high-pressure injection of cutting water without impairing the cutting effect.

Further, in the high-pressure injection stirring method of the present invention, the cutting composition comprising the abrasive-added polymer aqueous solution to which the abrasive is added may be directly injected. A fluidized abrasive prepared by adding and mixing the above-mentioned abrasive to a superabsorbent polymer that has been made to absorb water in advance is mixed at the tip of an abrasive nozzle having a double-pipe structure as shown in FIG. may By using an abrasive nozzle, the cutting impact pressure is improved, making it possible to cut cohesive ground, gravel ground, etc., which require pre-cutting (pledget), rubble in the ground, concrete blocks, wooden piles, etc.

(Stirring, mixing and solidifying step)
In the high-pressure injection stirring method of the present embodiment, after or at the same time as cutting with the above-described aqueous polymer solution or cutting composition consisting of an abrasive-added polymer aqueous solution, the solidifying material is discharged from the solidifying material discharge nozzle provided at the tip of the rod. to create a solidified body. Specifically, the solidification material prepared in advance on the ground is pumped and injected at a predetermined high pressure, and the excavated and pulverized soil to be improved and the solidification material are mixed and kneaded, and the rod is rotated to pull it up. Create a solidified body.

As a solidifying material for forming a solidified body, cement-based solidifying materials used in a normal high-pressure injection stirring method can be used. Cement-based solidifying materials such as crystalline calcium aluminates can be exemplified. These cement-based solidifying agents can be used singly or in combination of two or more.

Since the amount of solidifying material required to obtain a predetermined strength in the solidified body is determined by an indoor mixing test, the rod pulling-up speed is obtained by obtaining the amount of solidifying material in advance and pulling up the rod while discharging that amount. For the mixability of the mixed soil and the solidifying material, the injection pressure and other factors are determined in consideration of the mixing energy.

Basically, it is preferable that the solidifying material is discharged from the bottom of the excavation while being lifted up. It is also possible to discharge and mix while mixing and further pulling up.

In the cutting composition used in the high-pressure injection stirring method of the present embodiment, the highly water-absorbing polymer that swells by absorbing water does not dissolve in water, and further, by contact with the cement-based solidification material of the solidification agent, cement-based solidification When combined with divalent metal ions of Ca ²⁺ contained in the material, the water in the polymer is discharged by aggregation.

That is, when the cutting composition of the present invention is used for cutting, and a cement-based solidification material is used to form a solidified body, diffusion of the water jet is suppressed during cutting, and when the cement-based solidification material is mixed, the superabsorbent polymer is added. expels water and becomes less viscous. Therefore, it does not remain without disturbing the air lift of the discharged mud, and the quality of the formed body and the influence on the environment can be reduced.

In addition, when performing pre-cutting, water and mud can be easily separated by adding a separating agent such as calcium chloride to the discharged sludge that is not mixed with the cement-based solidifying material that is discharged to the ground. be able to.

Example 1 for confirming the cutting effect of the cutting composition comprising the aqueous solution of the added polymer according to the present invention and Example for confirming the cutting effect of the cutting composition comprising the aqueous solution of the abrasive-added polymer are described below. 2.

<Example 1: Cutting composition composed of additive polymer aqueous solution>
First, the superabsorbent polymers shown in Table 1 were mixed with water to prepare aqueous polymer solutions (four types) adjusted to a concentration of 1500 ppm and tap water.

Next, as shown in FIG. 3, a monitor with an injection nozzle (nozzle diameter 2.1 mm) at the tip of the rod was installed vertically in the air, and at distances of 50 cm, 100 cm, and 150 cm from the injection nozzle. A vertically erected concrete pressure plate (compressive strength of 20 N/mm ² , dimensions of 19 cm×19 cm×10 cm) was prepared.

Then, a cutting composition consisting of an aqueous polymer solution using polymers A to D and tap water were sprayed toward concrete pressure receiving plates erected at respective distances. The injection pressure was 35 kPa, the injection flow rate was 50 L/min, and the injection time was 2 minutes. FIG. 4A shows the relationship between the injection distance and the maximum cutting depth, and FIG. FIG. 5 shows a photograph of the surface condition of the concrete pressure-receiving plate to which tap water, polymer A, and polymer B were sprayed.

In addition, in order to confirm the difference between the jet of water and the jet of polymer aqueous solutions of polymer A and polymer B, backlight photography was performed using a high-speed camera (7000 frames/second), which is a water jet visualization technology. The photographed image is shown in FIG.

From the above results, it was found that injection of a cutting composition consisting of an aqueous polymer solution increased the maximum cutting depth and increased the mass reduction of the pressure plate due to erosion, as compared with injection of only water. Further, from the graph of FIG. 4(A), the maximum cutting depth is the highest in the cutting effect of the cutting composition using polymer B, which has high water absorption performance and has a relatively uniform particle size, at the injection distance of 150 cm. It was confirmed that the cutting composition using polymer B showed an increase twice that of water injection, and the cutting composition using polymer A also increased about 1.5 times that of tap water injection.

Further, from the graph in FIG. 4(B), the attenuation at the point of 150 cm from the point of 50 cm of injection distance was 30% attenuation with water injection, 15% attenuation with polymer B, and 10% attenuation with polymer A. Polymer A tended to be the most effective in terms of mass reduction of the pressure plate, but the surface mass reduction due to diffusion was large.

In addition, in the water jet visualized photograph taken with the backlight of a high-speed camera shown in FIG. In B, the effect was small, and in particular, as can be seen from FIG.

From the above results, it can be confirmed that, compared to tap water, the cutting composition consisting of an aqueous polymer solution diffuses less due to air resistance from the nozzle outlet to the injection destination, and has a longer potential core area where the injection speed is maintained. rice field. That is, it was confirmed that the injection of the cutting composition consisting of the aqueous polymer solution greatly improved the cutting performance compared to the conventional water injection. If the cutting ability is improved, it will be possible to create large diameter pits and shorten the creation time, so it will be possible to reduce the amount of injection and the volume of sludge discharged.

<Example 2: A cutting composition comprising an aqueous polymer solution containing an abrasive>
First, silica sand No. 6 (average particle size D ₅₀ =0.33 mm) was mixed with a water-absorbed aqueous polymer solution as an abrasive to prepare a fluidized abrasive. As the superabsorbent polymer, the superabsorbent polymer A (average particle size: 35 μm) was used, which had the best suspendability with almost no separation after the abrasive was mixed.

Next, as shown in FIG. 3, a monitor provided with a double structure abrasive nozzle (nozzle diameter 2.1 mm) shown in FIG. The jetted fluid was jetted toward concrete pressure receiving plates (compressive strength of 20 N/mm ² , dimensions of 19 cm×19 cm×10 cm) erected vertically at distances of 50 cm, 100 cm and 150 cm from the injection port of the nozzle. In addition, the abrasive nozzle adopts a central injection side supply system, and the diameter of the nozzle discharge port, the length of the straight part of the nozzle, and the nozzle inner surface constriction angle are adjusted in consideration of clogging of the nozzle port with abrasive material. It was set.

The cutting composition consisting of the fluid abrasive-added polymer aqueous solution was sprayed by pumping the polymer aqueous solution into the inner tube of the abrasive nozzle, pumping the fluid abrasive into the outer tube, and mixing and spraying at the tip of the nozzle. The fluid abrasive was pumped by a snake pump, and the aqueous polymer solution was pumped by a plunger pump.

First, in order to find the optimum amount of abrasive to be supplied in the fluidized abrasive, as a preliminary experiment, samples 1 to 3 shown in Table 2 were adjusted and directed toward a concrete pressure plate at a distance of 50 cm from the injection port of the nozzle. The injection fluid was injected at 50 L/min for 2 minutes, and the maximum cutting depth was measured. The concentration of each polymer aqueous solution was set to 1500 ppm. The relationship between the maximum cutting depth and the injection distance is shown in the graph of FIG. 8(A).

As shown in the graph of FIG. 8(A), the sand injection with polymer B and the abrasive has the largest cutting depth, and the sand injection with polymer A has the smallest cutting depth. The injection amount of the abrasive material has a turning point at 4 kg/min for injection with the polymer B, but with the polymers A and C, the excavation depth decreases as the supply amount of the abrasive material increases. From these results, the optimum abrasive feed rate in Example 2 was derived to be 4 kg/min.

Next, based on the results of the above preliminary experiment, a jetting experiment was conducted under the conditions shown in Table 3, with the supply amount of the abrasive in the fluidized abrasive fixed at 4 kg/min. For comparison, tap water was also sprayed under the same conditions.

Samples 4 to 7 and tap water were sprayed toward the concrete pressure plate under the same conditions as in the preliminary experiment, and the maximum cutting depth and mass reduction of the concrete pressure plate were measured. A graph of the relationship between the maximum cutting depth and the injection distance is shown in FIG. 8(B), and a graph of the relationship between the mass reduction amount and the injection distance is shown in FIG. 8(C). Also, tap water, a cutting composition consisting of the aqueous polymer solution B of Experiment 1, and Sample No. 2 in Table 2 were used. 5 was photographed in the same manner as jet photographing using a high-speed camera. The photograph is shown in FIG.

As can be seen from FIG. 8(B), the machinability of the abrasive injection according to the type of the superabsorbent polymer aqueous solution showed a tendency similar to that of injection experiment 1 using only the superabsorbent polymer aqueous solution. It was confirmed that the jetting was large compared to Polymers A and C.

4(A) and 4(B) of Experiment 1, regarding the superabsorbent polymer B having the highest machinability, the injection of only conventional water, the superabsorbent polymer aqueous solution B, and the sample No. in Table 2 . Comparing the relationship between the maximum cutting depth and injection distance of sample No. 5 and the amount of mass reduction due to erosion and injection distance, sample No. The depth of cutting by the cutting composition consisting of the abrasive-added polymer aqueous solution of No. 5 was slightly deeper than that of the injection of the polymer aqueous solution B alone, but was almost the same. On the other hand, the amount of mass reduction is the sample No. 5 was confirmed to be 1.1 to 1.6 times larger than that of the aqueous polymer solution.

Further, from the photograph taken by the high-speed camera shown in FIG. 9, the injection shape of the cutting composition comprising the abrasive-added polymer aqueous solution is almost the same as the injection shape of the cutting composition comprising the polymer aqueous solution. , it was confirmed that the abrasive did not diffuse and was contained in the aqueous polymer solution and injected. The continuous distance of the jet stream is about 50 cm for the jet of the cutting composition consisting of the aqueous polymer solution and the jet of the cutting composition consisting of the aqueous polymer solution containing the abrasive, and about 30 cm for the water jet. Also, the spread of the spray is clearly smaller for the cutting composition injection consisting of the aqueous polymer solution and for the sand injection compared to the water injection.

From these results, according to the cutting composition of the present invention, the injection of the abrasive-developed aqueous polymer solution did not diffuse, and the injection shape was equivalent to that of the aqueous polymer solution. It was confirmed that the amount of mass reduction was increased by the injection of the abrasive.

Claims (6)

A cutting composition used for cutting ground that is jetted from a jet nozzle,
A cutting composition comprising water and an aqueous polymer solution containing a sodium polyacrylate superabsorbent polymer swollen by absorbing water. 2. The cutting composition according to claim 1, wherein said aqueous polymer solution contains an abrasive. The aqueous polymer solution containing the abrasive is a mixture of a fluid abrasive comprising an abrasive and a sodium polyacrylate superabsorbent polymer, and an aqueous polymer solution containing water and a sodium polyacrylate superabsorbent polymer swollen by absorbing water. 3. The cutting composition according to claim 2, characterized in that it is a shaving composition. 4. A cutting composition according to claim 2, wherein said abrasive is silica sand. The ground is cut by inserting a rod equipped with a cutting water injection nozzle and a solidifying material injection nozzle into the ground, rotating and pulling it up, and injecting cutting water at high pressure from the cutting water injection nozzle toward the ground improvement area. a cutting process;
While rotating and pulling up the injection rod inserted into the ground, the solidification material and the excavated ground are stirred and mixed to solidify by injecting the solidification material from the solidification material injection nozzle at high pressure toward the ground improvement area. In the high-pressure injection stirring method having a solidification process,
A high-pressure injection stirring method, wherein the cutting composition according to any one of claims 1 to 4 is used as the cutting water. In the ground cutting step, each of a fluidized abrasive composed of an abrasive and a sodium polyacrylate superabsorbent polymer, and an aqueous polymer solution containing water and a sodium polyacrylate superabsorbent polymer swollen by absorbing water is used for cutting. 6. The high-pressure jet stirring method according to claim 5, wherein the fluid is pressure-fed to the tip of the water jet nozzle, mixed in the cutting water jet nozzle, and jetted as the cutting water at high pressure.

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