JP6909642B2 - Manufacturing method of fluidized sand - Google Patents

Description

The present invention is a method for producing fluidized sand in which a fluidizing agent is mixed with a sand material used for ground improvement so that the sand material can be pumped.

Of the ground improvement methods, the sand compaction pile method (SCP method) is often used as a countermeasure against liquefaction, and increases the density of the ground by creating compacted sand piles in the ground. Since this SCP construction method uses a large construction machine, it is often not applicable due to restrictions on securing construction space. As an alternative method, a chemical injection system using a small construction machine or a method of press-fitting cement mortar may be applied, but the cost is high. In addition, a construction method that enables the use of material sand, which is a natural material that can reduce the environmental load, has been desired. Against this background, as disclosed in Patent Documents 1 and 2, the applicants put the material sand into a fluidized state that can be pumped and press-fit it into the ground to reduce costs and reduce the environmental load. We have developed a press-fit sand pile construction method that enables reduction and have already put it into practical use. This method is called the sand press-fit type static compaction method or the SAVE-SP method (registered trademark), and can be used for construction in narrow areas and improvement directly under existing structures by using a small construction machine.

Patent Document 1 discloses the basics of the press-fitting sand pile construction method. In this construction method, a sand pile material fluidized product (hereinafter referred to as fluidized sand) containing a fluidizing agent and a slow-acting plasticizing agent together with water for adjusting the water content ratio in the material sand is placed in the ground while maintaining the fluidized state. Press-fit and plasticize in the ground. In this detail, as illustrated in FIG. 11, the hollow pipe 23 is penetrated into the ground to the design depth, and then the fluidized sand is press-fitted from the ground surface to the ground through the hollow pipe 23, and the fluidized sand is injected into the ground. The fluidized sand for the next step is press-fitted onto this, and by repeating this, an improved body 25 having a predetermined length is created. Reference numeral 10 is a fluidized sand production plant, 1 is a fluidized sand supply means, 2 is a sand material supply means, 3 is a fluidizer supply means, 4 is a pumping pump, and 5 is a slow-acting plasticizer supply device.

Patent Document 2 discloses a plant for producing fluidized sand. In this production plant, a fluidizing agent is mixed with the material sand to produce fluidized sand, and the fluidized sand is mixed with water, a fluidizing agent, and a slow-acting plastic agent in this order. Preferably, the fluidized sand weighs the sand material, and based on the weight, water, a fluidizing agent, and a slow-acting plastic agent are automatically calculated and mixed.

FIG. 12 is a schematic view showing a change of state of fluidized sand during construction. (A) shows the fluidized sand before press fitting. In fluidized sand, a fluidizing agent (for example, anionic polymer material) increases the viscosity of the interstitial water between sand particles until it is press-fitted into the ground from a hollow tube, eliminating friction between the particles and forming sand. It suppresses separation from water and maintains high fluidity. (B) shows the fluidized sand during press fitting. During press fitting, the fluidized sand is dehydrated and compacted into a dense state. The fluidizing agent remains reticulated. (C) shows the plasticization end state. In this state, the slow-acting plasticizing agent electrically neutralizes the fluidizing agent and cannot maintain the network structure of the fluidizing agent, thus recovering the friction between the particles.

Japanese Patent No. 5188894 Japanese Patent No. 5189951

In the press-fitting sand pile construction method using the fluidized sand, a hollow pipe having a diameter of about 100 to 200 mm is used, and an improved body having a diameter of about 500 to 700 mm is often created by underground press-fitting of the fluidized sand. .. At the time of construction, the characteristics of the target ground are grasped by a preliminary survey, and the material sand is selected and the compounding specifications are determined accordingly, and the applicability of the manufactured fluidized sand is determined by table flow test, bleeding test, and texture test. Judgment is made and whether or not it can be used is decided. In addition, regarding the raw material sand, a specified range that can be used is set in terms of particle size distribution and the like.

However, in reality, even for material sand within the specified range, the penetration resistance may increase at an early stage, making it difficult to apply. That is, depending on the material sand used, when the sand is press-fitted into the ground as fluidized sand, the pressure increases in a short time or the pumping loss increases, so that the press-fitting amount does not reach the target value. The applicant has investigated the cause, but the main factor is that the cations such as metal ions contained in the material sand react with the polymer material that is the fluidizing agent and affect each other, which is the target value. However, it is considered that the performance drops sharply.

As a result of studying measures to prevent the above-mentioned sudden changes in properties, the applicant has found that cations such as metal ions, which are inhibitory factors, can be chemically or chemically and physically eliminated, leading to the present invention. rice field. An object of the present invention is that even material sand, which is difficult to apply when applying the press-fit sand pile construction method or the sand filling method, is produced over time as fluidized sand produced by mixing an additive for ionic charge neutralization. The purpose is to improve the properties and make them applicable. Other purposes or specific purposes will be clarified in the following explanation.

In order to achieve the above object, the invention of claim 1 is a method for producing fluidized sand for ground improvement, in which a fluidizing agent is added to the material sand together with water for adjusting the water content to be transferred through a pipe by a pumping pump. An additive for ionic charge neutralization is added to a predetermined amount of the material sand so that cations such as metal ions, which are contained in the material sand and hinder the fluidizing agent, can be charge-neutralized with respect to the material sand. , was mixed 100Ppm～1000ppm, it is characterized by the incorporation of the fluidizing agent.

In the above invention, the cations such as metal ions that hinder the fluidizing agent contained in the material sand include metal ions having a divalent value or higher, such as calcium ion (Ca ²⁺ ) and magnesium ion (Mg ²⁺ ). ^Examples include iron ions (Fe 2+, Fe ³⁺ ) and aluminum ions (Al ³⁺ ). On the other hand, the additive for ionic charge neutralization is an inorganic charge neutralizing agent such as sodium hydrogen carbonate or an organic charge neutralizing agent such as tetrasodium imodisuccinate. These points will be described later.

It is more preferable that the above invention is further embodied as follows. That is,
First, the ionic charge neutralizing additive is sodium hydrogen carbonate (NaHCO ₃ ), sodium carbonate (Na ₂ CO ₃ ), sodium tripolyphosphate (Na ₅ P ₃ HCO ₁₀ ), sodium polyacrylate (C). ₃ H ₃ NaO ₂ ) An inorganic charge neutralizer such as _{n (claim 2).}
Second, the ionic charge neutralizing additives, 3- hydroxybenzoic 2,2' iminodisuccinic acid tetrasodium _{(C 8 H 7 NO 9 ·} 4Na), tetrasodium ethylenediaminetetraacetate tetrahydrate _{(C 10} H a _{12 N 2 O 8 Na 4 ·} 4H 2 O) the organic charge neutralizing agents such (claim 3). In addition, this organic charge neutralizing agent is generally called a chelating agent, and may also be referred to as an organic charge retarding agent.

Thirdly, the fluidized sand has a configuration in which the intrusive stress value of the fluidized sand at least 1 hour after the texture test is about 6,000 (Pa) or less (claim 4).

The invention of claim 1 is to mix cations (particularly divalent or higher valent metal ions) contained in the raw material sand with the raw material sand with an ionic charge neutralizing additive capable of charge neutralizing, and then flow. By mixing the agent, the properties of the fluidized sand over time are improved and normal press-fitting can be maintained. In this case, from various tests, the timing of mixing the ionic charge neutralizing additive with the raw material sand is important, and it can be improved by mixing it with the material sand at the same time as the fluidizing agent or after mixing the fluidizing agent. The effect cannot be expected so much. This indicates that it is essential to mix the ionic charge neutralizing additive with the material sand in advance to eliminate or suppress the inhibitory factor before mixing the fluidizing agent with the material sand.

As described above, the fluidized sand of the present invention can be used as the raw material sand, which is not applicable even though it satisfies the specified range such as particle size distribution. The range of application of the material sand used can be expanded, which in turn can contribute to cost reduction and expansion of application opportunities for the ground improvement method using fluidized sand.

In the invention of claim 2, as an additive for ionic charge neutralization, as is clear from the test examples described later, an inorganic charge neutralizer such as sodium hydrogen carbonate, sodium carbonate, sodium tripolyphosphate, sodium hexametaphosphate, etc. is used as a raw material. By mixing with the material sand, the factors that inhibit the properties of the fluidized sand can be reliably improved by the reaction or inhibitory action.

In the invention of claim 3, as an additive for ionic charge neutralization, as is clear from the test examples described later, organic charges such as 3-hydroshiki-2,2'-iminodisuccinate tetrasodium, ethylenediaminetetraacetic acid tetrasodium tetrahydrate, etc. By mixing the neutralizing agent with the raw material sand, the factors that inhibit the properties of the fluidized sand can be reliably improved by the reaction or suppressing action.

In the invention of claim 4, the penetration stress which is particularly important as the property of the fluidized sand after the improvement, that is, the penetration stress of the fluidized sand after 1 hour of preparation from the texture test is improved to 6,000 (Pa) or less. The point is specified. It is significant that this value clearly specifies that it satisfies the standard value that is considered preferable in the current implementation work.

It is a schematic view for explanation showing the device configuration for implementing the present onset bright. It is a graph which shows the texture test result among the physical characteristic test results of fluidized sand (an example of an additive for ionic charge neutralization is sodium hydrogen carbonate) to which this invention is applied. It is a graph which shows the flow test result among the physical property test results of the fluidized sand (an example of an additive for ionic charge neutralization of sodium hydrogen carbonate) used in FIG. It is a graph which shows the texture test result among the physical characteristic test results of the fluidized sand to which this invention was applied (the additive for ion charge neutralization is an example of sodium carbonate). It is a graph which shows the texture test result among the physical characteristic test results of the fluidized sand to which this invention was applied (the additive for ion charge neutralization is an example of sodium tripoliphosphate). It is a graph which shows the texture test result among the physical characteristic test results of fluidized sand (an example of sodium polyacrylate as an additive for ion charge neutralization) to which this invention was applied. It is a graph which shows the texture test result among the physical characteristic test results of the fluidized sand to which this invention was applied (the additive for ion charge neutralization is an example of sodium hexametaphosphate). It is a graph which shows the texture test result among the physical characteristic test results of the fluidized sand to which this invention was applied (the additive for ion charge neutralization is an example of HIDS). It is a graph which shows the flow test result among the physical characteristic test results of the fluidized sand used in FIG. 8 (an additive for ion charge neutralization is an example of HIDS). It is a graph which shows the texture test result among the physical characteristic test results of the fluidized sand to which this invention was applied (the additive for ion charge neutralization is an example of Kirest OD). It is explanatory drawing which shows the sand pile making apparatus disclosed in Patent Document 1. (A) to (c) are explanatory views which show the state change of fluidized sand at the time of construction.

Hereinafter, a form example to which the present invention is applied will be described with reference to the drawings. In this explanation, the construction machine used for the sand press-fit type static compaction method and sand filling method, the fluidized sand production plant, the fluidized sand production method, and the sand press-fit type static compaction method which is a ground improvement method are described. After that, the physical property test results of the fluidized sand produced in Examples 1 to 5 as Test Example 1 and Examples 6 and 7 as Test Example 2 will be described.

(Ground improvement method) The fluidized sand produced in the present invention is used in the ground improvement method . The construction machines used in the construction method are roughly divided into a crawler type that penetrates and pulls out the hollow pipe vertically along the leader, and a boring machine type that penetrates and pulls out the hollow pipe while hanging it on an auxiliary crane. There is a rotary percussion drill type that penetrates or pulls out a hollow pipe at an arbitrary angle, and it is selected according to the target ground and construction depth.

FIG. 1 is an example of a small crawler type construction machine 1, which is schematically shown together with a fluidized sand production plant 2. The construction machine 1 includes an elevating mechanism 4 that moves the hollow pipe 3 up and down, a rotating mechanism 5 that is held by the elevating mechanism 4 and rotates the hollow pipe 3, and a swivel provided at the upper end 3a of the hollow pipe. 15 and the pump P for pumping the fluidized sand produced in the manufacturing plant 2, the conduit 16 connecting the outlet of the pump P and the swivel 15, and the conduit 16 provided in the middle of the conduit 16 for pumping. A pressure gauge 6 for detecting the pressure of fluidized sand is provided.

Here, the elevating mechanism 4 is moved up and down along one side of the columnar leader 12 movably erected by the base machine 10 via a rack and pinion mechanism or the like. The rotation mechanism 5 is moved up and down along the leader 12 by the elevating mechanism 4, and the hollow pipe 3 is rotated forward and backward via a motor, a reduction gear mechanism, and the like. The base machine 10 positions and holds the lower end side of the leader 12 in front of the driver's cab 11, and mounts a hydraulic device, an electric motor, or the like (not shown) on the rear side of the driver's cab 11. Various construction operation units and control units are arranged in the driver's cab 11. The leader 12 is supported by a raised cylinder 13 or the like, and is attached to the lower side to regulate the runout of the hollow pipe 3, and is attached to the upper side to support the upper side of the pipe line 16. And so on. The upper end of the pipeline 16 is connected to the upper end 3a of the hollow pipe 3 via a swivel 15.

As the pump P, a type having a pumping structure using a hydraulic piston is selected because it does not cause particularly high suction force, airtightness, and air suction, and changes in fluidized sand properties can be suppressed to a low level. The pump drive is automatically controlled via a control unit arranged in the driver's cab 11 or controlled by the operator. The pressure gauge 6 detects the pressure of the fluidized sand pumped by the pump P and is press-fitted into the ground side region from the lower end opening of the hollow pipe 3, that is, the portion where the density is lowered by pulling out the hollow pipe and its surroundings. Makes it possible to estimate the press-fitting pressure of the fluid at that time. Then, the pressure gauge 6 detects the pressure at the time of pumping the fluidized sand at the time of construction, and transmits the detection signal to the control unit of the operation cab 11. In the control unit, the pump P is driven and stopped when the set press-fitting pressure is reached as the press-fitting pressure of the fluid based on the detection signal.

(Fluidized sand production plant) This production plant 2 is centered on a production apparatus 20 having a mixing chamber 21 and an agitator chamber 22, and a sand supply means 23 such as a back hoe that feeds sand material 7 into the mixing chamber 21. , Additive supply means 24 for supplying an additive for ion charge neutralization, fluidizer supply means 25 for charging a fluidizing agent, water supply means 26 for supplying water for adjusting the water content, and a plasticizing agent. The plasticizing agent supply means 27 is provided.

When applying the sand press-fit type static compaction method, the selection of material sand and the compounding specifications will be determined according to the characteristics of the target ground by a preliminary survey. In the manufacturing plant 2, the target fluidized sand is usually produced in the mixing chamber 21 for each batch amount (improved body 9). The material sand 7 charged by the sand supply means 23, the ionic charge neutralizing additive supplied by the additive supply means 24, the fluidizer charged by the fluidizer supply means 25, and the water supply means 26 are supplied. The selection criteria and actions of the water and the plasticizing agent supplied by the plasticizing agent supplying means 27 will be clarified below.

(1) Since the material sand 7 is pumped in a state where the fluidity is once increased, it is preferable that the material sand 7 has both good water retention that does not block in the pipe and good drainage that dehydrates at the time of press fitting. For this point, refer to FIG. 6 of Japanese Patent Application Laid-Open No. 2015-183466 and related descriptions thereof. Further, as the material sand 7, although it varies depending on the collection place, there is a material sand containing a metal ion having a divalent value or more as a cation which is an inhibitory factor of the fluidizing agent. Examples of the divalent or higher metal ion include calcium ion (Ca ²⁺ ), magnesium ion (Mg ²⁺ ), iron ion (Fe ²⁺ , Fe ³⁺ ), aluminum ion (Al ³⁺ ) and the like. The material sand to be invented contains unusual irregular sand, that is, cations in which the sand acts as an inhibitor of the fluidizing agent. It is sand that is judged to be difficult to apply to the construction method. Therefore, in the case of other materials, that is, ordinary material sand, it is of course not necessary to mix the additive for ionic charge neutralization of the present invention.

(2) The additive for ionic charge neutralization is an inhibitory factor of the fluidizing agent by mixing with the above material sand 7, that is, a metal having a valence of 2 or more as the above-mentioned cation contained in the material sand. It is an inorganic charge neutralizing agent suitable for neutralizing ions in terms of ionic charge, or an organic charge neutralizing agent particularly suitable for neutralizing or blocking metal ions having a valence of trivalent or higher. Next, a specific example will be given.

Examples of the inorganic charge neutralizer include sodium hydrogen carbonate (NaHCO ₃ ), sodium carbonate (Na ₂ CO ₃ ), sodium tripolyphosphate (Na ₅ P ₃ HCO ₁₀ ), and polyacrylic used in Examples 1 to 5 described later. Sodium acid (C ₃ H _{3 NaO 2} ) _n , sodium hexametaphosphate (NaPO ₃ ) _6, etc. It has been confirmed in the tests of the present inventors that potassium chloride (NaCl), sodium chloride (NaCl), potassium carbonate (K ₂ CO _{3) and the like are also effective as other additives for ionic charge neutralization.} In contrast, as the organic charge neutralizer, 3-hydroxybenzoic 2,2' iminodisuccinic acid tetrasodium used in Example _{8~10 (C 8 H 7 NO 9} · 4Na), ethylenediaminetetraacetic acid tetrasodium four it is a tetrahydrate _{(C 10 H 12 N 2 O} 8 Na 4 · 4H 2 O) and the like.

For example, it is only speculated how the additive for ionic charge neutralization neutralizes divalent or higher metal ions contained in the material sand in terms of ionic charge, but it is based on the following reaction. It is considered to be. As an example, when the additive for ionic charge neutralization is sodium hydrogen carbonate (NaHCO ₃ ) as an inorganic charge neutralizing agent, for example, with respect to calcium ion (Ca ²⁺ ) and magnesium ion (Mg ²⁺ ) contained in the material sand (Mg 2+). 1) Ca ²⁺ + NaHCO ₃ = CaCO ₃ + (Na ⁺ + H ⁺ )
(2) Mg ²⁺ + NaHCO ₃ = MgCO ₃ + (Na ⁺ + H ⁺ )
^{It is considered that Ca 2+} and Mg ²⁺ , which are divalent or higher metal ions, are neutralized in terms of ionic charges by the reaction formulas (1) and (2) to eliminate or suppress the inhibiting factor of the fluidizing agent. ..

The above additives for ionic charge neutralization cannot be expected to have much improvement effect even if they are mixed with the raw material sand at the same time as the fluidizing agent, and further, if they are mixed after mixing the fluidizing agent with the material sand, the improving effect can be obtained. do not have. That is, in the raw material sand, cations, particularly divalent or higher valent metal ions, are neutralized in terms of ionic charge with an ionic charge neutralizing additive as an inhibitory factor of the fluidizing agent contained in the material sand. After eliminating or suppressing the inhibiting factor in advance, the fluidizing agent is mixed. The mixing ratio of the additive to the raw material sand is a flow prepared by mixing the additive with the target material sand and then mixing the fluidizing agent and the water for adjusting the water content ratio, as inferred from the examples described later. For fluidized sand or fluidized sand prepared by mixing a fluidizing agent, water for adjusting the water content ratio, and a slow-acting plasticizing agent, the properties of the fluidized sand are determined in advance by a texture test, a flow test, or the like. Values that fall within the range will be confirmed and determined through tests.

(3) Water is for adjusting the water content ratio, and avoid industrial water and seawater containing various components that affect fluidizing agents (cations such as the above-mentioned metal ions), and use neutral tap water. It is preferable to use it. The amount of water used is usually calculated so that the water content of the produced fluidized sand is 30% to 40%.

(4) The fluidizing agent is an additive that increases the viscosity of interstitial water between sand particles, suppresses the separation of sand and water in a saturated state, and improves pumping performance. Preferably, it is an anionic polymer flocculant that increases viscosity and suppresses sedimentation and separation of sand particles, and may also be a nonionic polymer flocculant, a cationic polymer flocculant, or the like. These are excellent in the ability to retain water inside the hydrophilic group of the polymer and the network of the polymer, and have high long-term stability of quality. Examples of the anionic polymer flocculant include homopolymers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylamide2-methylpropane sulphonic acid, vinyl sulphonic acid, and styrene sulphonic acid, or copolymers with acrylamide. Can be mentioned.

The blending ratio of the fluidizing agent is 0.01 to 2.0% by weight, preferably 0.1 to 1.0% by weight, based on the outer composition of the material sand. If this mixing ratio is too small, the material sand will not be fluidized, and it will be separated or clogged in the pipe, making it impossible to pump, and if it is too large, the fluidization effect will not change, and the cost will increase. It will be.

(5) The amount of the slow-acting plasticizing agent used is a blending amount capable of plasticizing the fluidized sand, and is 0.001 to 2 weight by external splitting with respect to the material sand in the fluidized sand to be produced. %, Preferably 0.01 to 1.0% by weight. If this amount is too small, the fluid will not be plasticized and it will not be possible to create an improved product as designed. If too much is added, plasticization will occur quickly, which will hinder pump pumping and at the same time be costly. Become.

(Manufacturing method of fluidized sand) In the production plant 2, it was judged that it is difficult to apply the raw material sand from the texture test, etc. when producing the fluidized sand used for the sand press-fit type static compaction method and the sand filling method. In this case, the desired fluidized sand will be produced in the following manner. First, the required amount of ionic charge neutralizing additive is uniformly mixed with a predetermined amount of material sand 7 corresponding to one batch amount, or the water content ratio is adjusted together with the required amount of ionic charge neutralizing additive. Mix the water. Then, a fluidizing agent and a slow-acting plasticizing agent are added to prepare fluidized sand. For example, these are prepared by mixing a fluidizing agent or a fluidizing agent and water for adjusting the water content ratio, or a fluidizing agent and water for adjusting the water content ratio and a slow-acting plasticizing agent with the material sand to prepare fluidized sand. This is because even if an additive for ionic charge neutralization is mixed, the properties of the produced fluidized sand over time are not improved. That is, in the stage before mixing the fluidizing agent with the raw material sand, an additive for ionic charge neutralization is mixed and an inhibitory factor of the fluidizing agent contained in the material sand (metal ions as cations, particularly divalent or higher). It is essential to eliminate or suppress the metal ions).

(Sand press-fitting static compaction method) This method is as follows in the example of using the construction machine 1 of FIG. First, the operation procedure consists of a drawing step of penetrating the hollow pipe 3 through the elevating mechanism 4 to the design depth in the ground and then pulling out by a predetermined pitch, and a drawing step of the density that can be formed below the hollow pipe 3 in the pulling step. An improved body 9 having a predetermined length is created by repeating a supply step of press-fitting fluidized sand into a low region and its surroundings. In the construction management, in the control unit of the driver's cab 11, the maximum penetration depth (lower end depth) of the hollow pipe 3, the pull-out length L for one pitch, the total number of pitches ((lower end depth-upper end depth) / L), Values such as set press-fit (discharge) pressure are input to the program. Further, the produced fluidized sand is prepared in the agitator section 22.

At the time of construction, after the construction machine 1 is moved to the construction location and positioned, the hollow pipe 3 is operated to penetrate into the ground while being rotated via the elevating mechanism 4 and the rotating mechanism 5. This penetration is determined by a signal from a depth gauge (not shown) whether or not the lower end of the hollow pipe 3 has reached the design depth (lower end depth), and when the lower end reaches the design depth, the elevating mechanism 4 and the like are moved. Penetration is stopped through.

Next, the control unit controls via the elevating mechanism 4 to start pulling out the hollow pipe 3 by one pitch (for example, 20 cm), and at the same time, the pump P is operated to pump the fluidized sand. Control is performed so that the region formed below the hollow tube 3 and its surroundings are press-fitted with the drawing. That is, the control unit determines whether or not the withdrawal has reached one pitch, and when it is determined that the withdrawal has reached one pitch, the elevating mechanism 4 is controlled to stop or enter an idling state. Further, the control unit determines whether or not the press-fitting pressure of the fluidized sand discharged to the above-mentioned region has reached the set value as the press-fitting state of the fluidized sand based on the detection signal sent from the pressure gauge 6. When it is determined that the press-fitting pressure has reached the set pressure, the pump P stops or switches the on-off valve (not shown) to the closed state.

Further, in the above control unit, it is determined whether or not the total number of pitches or all pitches have been drawn out, and the drawing out and the press-fitting of the fluidized sand are repeated until the total number of pitches is reached. Further, when the total number of pitches is reached, one improved body 9 is terminated. After that, the ground improvement device 1 is moved to the next construction site and positioned, and then the above operation is performed again.

(Example) Hereinafter, Examples 1-5 shown in FIGS. 1 to 7 can be applied to the material sand of the raw material (this material sand can be applied to the sand press-fit type static compaction method and the sand filling method from the texture test and the like. Of the additives for ionic charge neutralization, sodium hydrogen carbonate (NaHCO ₃ ) was used as an inorganic charge neutralizer, and sodium carbonate (NaHCO 3) was used as an inorganic charge neutralizer in Example 2 (which is the raw material sand judged to be difficult). Na ₂ CO ₃ ), sodium tripolyphosphate (Na ₅ P ₃ HCO ₁₀ ) in Example 3, sodium hexametaphosphate (NaPO _{3 ) 6} in Example 4, sodium polyacrylate (C) in Example 5. ₃ H ₃ NaO ₂ ) _{After mixing n} , water for adjusting the water content ratio, fluidizing agent, and slow-acting plasticizing agent were mixed at a predetermined ratio for each fluidized sand, and FIGS. 2 and 4 to 4 to 4 The test results when the texture test of FIG. 7 and the flow test of FIG. 3 were performed are summarized in a graph.

Further, Examples 6 and 7 shown in FIGS. 8 to 10 are found to be difficult to apply to the raw material sand (this material sand is difficult to apply to the sand press-fit type static compaction method and the sand filling method from the texture test and the like. Of the additives for ionic charge neutralization, in Example 6 as an organic charge neutralizer, 3-hydroshiki-2,2'-minodisuccinate tetrasodium (C ₈ H ₇ NO _{9) was added to the determined raw material sand.} · 4Na) and, after mixing example 7 In tetrasodium ethylenediaminetetraacetate tetrahydrate _{(C 10 H 12 N 2 O} 8 Na 4 · 4H 2 O), water content adjusted water, flowing agents, slow-acting plastic The test results when the texture test of FIGS. 8 and 10 and the flow test of FIG. 9 were performed on each fluidized sand prepared by mixing the agents at a predetermined ratio are summarized in a graph.

In the texture test, a predetermined container is filled with fluidized sand (sample), set in a tabletop physical property measuring instrument manufactured by Yamaden Co., Ltd. as a commercially available texture test device, and then the cylinder is moved up and down at a constant speed from the top surface of the sample. Perform 20 mm penetration and withdrawal. The penetration stress is a value obtained by converting the maximum load ha at the time of penetration into stress. The flow (table flow) test was carried out in accordance with the cement physical characteristic test method (JIS R5201-1997).

Example 1: In FIGS. 2 and 3, _{0 ppm, 100 ppm, 500 ppm, and 1000 ppm of NaHCO 3} are mixed with a predetermined amount of material sand as a mixing ratio, and then water for adjusting the water content ratio, a fluidizing agent, and slow-acting plasticization are performed. The results of a texture test (hardness) and a flow test (fluidity) of four types of fluidized sand prepared by mixing the agents at a predetermined ratio are shown. In the figure, the composition of NaHCO ₃ , which is an additive for ionic charge neutralization, is 0 ppm for black circles, that is, a sample not mixed, a sample with 100 ppm for squares, a sample with 500 ppm for white circles, and a sample with 1000 ppm for triangles. From this test result, the penetration stress in Fig. 2 is significantly smaller than that of the conventional sample without sodium hydrocarbon, even if it is mixed at 100 ppm. When sodium hydrocarbon is added to 14,880 Pa (Pa), the change in properties is suppressed to 10,000 (Pa), and by mixing 1000 ppm of sodium hydrocarbon, the standard value, that is, 3 hours of preparation It can be seen that even the penetration stress of the later fluidized sand is improved to about 5,878 (Pa), that is, to 6,000 (Pa) or less.

Further, from the flow test results of FIG. 3, it can be seen that the fluctuation of the table flow value (mm) depending on the presence or absence of mixing of sodium hydrocarbon is hardly observed, and the influence of the fluidized sand on the table flow value can be ignored. The inorganic charge neutralizing agent, which is an additive for ionic charge neutralization, may be mixed with the material sand in a powder state or mixed with the material sand in a state of being dissolved in water. Generally, the latter method is preferable from the viewpoint of uniform mixing. In this case, the water used will be treated as a part of the water content adjusting water.

Example 2: FIG. 4 shows water for adjusting the water content ratio, a fluidizing agent, and a slow-acting plasticizing agent after mixing 0 ppm, 100 ppm, 500 ppm, and 1000 ppm of _{Na 2} CO _{3 as a mixing ratio with a predetermined amount of material sand.} The results of examining the texture test (hardness) of four types of fluidized sand produced by mixing the above in a predetermined ratio are shown. In the figure, the composition of NaCO ₃ , which is an additive for ionic charge neutralization, is 0 ppm for black circles, that is, a sample not mixed, a sample with 100 ppm for squares, a sample with 500 ppm for white circles, and a sample with 1000 ppm for triangles. From this test result, the penetration stress is significantly smaller than that of the conventional sample in which sodium carbonate is not mixed, even if only 100 ppm is mixed. In other words, for example, looking at the change over time 3 hours after preparation, the change in properties was suppressed to 10,970 (Pa) when the additive was added to 14,880 (Pa) when no additive was added. The point is that by mixing 500 ppm of sodium carbonate, the reference value, that is, the penetration stress of fluidized sand after 3 hours of preparation is improved to 6,000 (Pa) or less, and the penetration stress is 500 ppm of sodium carbonate. It can be seen that there is not much change between the case of mixing and the case of mixing 1000 ppm. Although the flow test was omitted, as in Example 1, the table flow value (mm) did not fluctuate depending on the presence or absence of sodium carbonate mixing, and the effect of the fluidized sand on the table flow value was negligible. ..

Example 3: FIG. 5 shows that after mixing 0 ppm, 100 ppm, 500 ppm, and 1000 ppm of _{sodium tripolyphosphate (Na 5} P ₃ HCO _{10) as a mixing ratio with a predetermined amount of material sand, water for adjusting the water content ratio, flow.} The results of a texture test (hardness) of four types of fluidized sand prepared by mixing an agent and a slow-acting plasticizing agent at a predetermined ratio are shown. In the figure, the formulation of Na ₅ P ₃ HCO ₁₀ , which is an additive for ionic charge neutralization, is 0 ppm for black circles, that is, a sample that is not mixed, a sample that is mixed with 100 ppm for squares, a sample that is mixed with 500 ppm for white circles, and 1000 ppm for triangles. It is a sample. From this test result, the penetration stress is significantly smaller than that of the conventional sample without sodium tripolyphosphate, even if it is mixed at 100 ppm. When sodium tripolyphosphate was added to 880 (Pa), the change in properties was suppressed to 7,970 (Pa), and by further mixing 1000 ppm of sodium polyphosphate, the flow after 3 hours of preparation. It can be seen that even the penetration stress of the fossilized sand is 3,807 (Pa), which is improved to the reference value of 6,000 (Pa) or less. Although the flow test was omitted, as in Example 1, the table flow value did not fluctuate depending on the presence or absence of mixing of sodium tripoliphosphate, and the effect of the fluidized sand on the table flow value was negligible.

Example 4: FIG. 6 shows water for adjusting the water content ratio after mixing 0 ppm, 100 ppm, 500 ppm, and 1000 ppm of _{sodium polyacrylate (C 3} H ₃ NaO ₂ ) _{n as a mixing ratio with a predetermined amount of material sand.} The results of a texture test (hardness) of four types of fluidized sand prepared by mixing a fluidizing agent and a slow-acting plasticizing agent at a predetermined ratio are shown. In the figure, the formulation of (C ₃ H ₃ NaO ₂ ) _n , which is an additive for ionic charge neutralization, is 0 ppm for black circles, that is, a sample that is not mixed, a sample that is mixed with 100 ppm for squares, a sample that is mixed with 500 ppm for white circles, and a triangle. It is a sample mixed with 1000 ppm. From this test result, the penetration stress is significantly smaller than that of the conventional sample without sodium polyacrylate, even if it is mixed at 100 ppm. When the additive was added to 880 (Pa), the change in properties was suppressed to 9,389 (Pa), and by mixing 1000 ppm of sodium polyacrylate, the standard value, that is, 3 hours after preparation. It can be seen that even the penetration stress of fluidized sand is improved to 6,000 (Pa) or less. Although the flow test was omitted, as in Example 1, fluctuations in the table flow value due to the presence or absence of mixing of sodium polyacrylate were hardly observed, and the effect of the fluidized sand on the table flow value was negligible.

Example 5: In FIG. 7, water for adjusting the water content ratio, a fluidizing agent, after mixing 0 ppm, 100 ppm, 500 ppm, and 1000 ppm of _{sodium hexametaphosphate (NaPO 3} ) _{6 as a mixing ratio with a predetermined amount of material sand.} The results of a texture test (hardness) of four types of fluidized sand prepared by mixing slow-acting plasticizing agents at a predetermined ratio are shown. In the figure, the ionic charge neutralizing additive (NaPO ₃ ) ₆ is mixed with 0 ppm of black circles, that is, a sample not mixed, a sample of 100 ppm of squares, a sample of 500 ppm of white circles, and a sample of 1000 ppm of triangles. Is. From this test result, the penetration stress is significantly smaller than that of the conventional sample without sodium hexametaphosphate, even if it is mixed at 100 ppm. When the additive was added to 880 (Pa), the change in properties was suppressed to 7,257 (Pa), and the change in penetration stress due to the blending ratio of sodium hexametaphosphate, for example, 2 hours after preparation. Comparing the penetration stress of fluidized sand, the penetration stress is the smallest at 6,000 (Pa) at 100 ppm, the penetration stress is larger at 500 ppm, about 7,000 (Pa), and the penetration stress is 1000 ppm. Since the value is 9,000 (Pa), which is even larger, it can be seen that the optimum blending ratio must be verified and determined by a preliminary test when selecting a specific additive for ion charge neutralization. Although the flow test was omitted in Example 5, as in Example 1, fluctuations in the table flow value due to the presence or absence of mixing of sodium hexametaphosphate were hardly observed, which affected the table flow value of the fluidized sand. The impact is negligible.

Example 6: In FIGS. 8 and 9, 0 ppm of 4-sodium 3-hydroshiki-2,2'-iminodicosuccinate (hereinafter referred to as HIDS) as an organic charge neutralizing agent is mixed with a predetermined amount of material sand. Texture test (hardness) for four types of fluidized sand prepared by mixing 600 ppm, 1200 ppm, and 2400 ppm, and then mixing water for adjusting the water content ratio, fluidizing agent, and slow-acting plasticizing agent at predetermined ratios. And the result of examining the flow test (fluidity) are shown. In the figure, the composition of HIDS, which is an organic charge neutralizer, is 0 ppm for black circles, that is, a sample not mixed, a sample with 600 ppm for squares, a sample with 1200 ppm for white circles, and a sample with 2400 ppm for triangles. From this test result, the intrusive stress in FIG. 8 is significantly smaller than that of the conventional sample without HIDS even if it is mixed with 600 ppm. When 600 ppm of HIDS is mixed with 380 (Pa), the change in properties is suppressed to 6,378 (Pa). By mixing 2400 ppm of HIDS, the reference value, that is, the fluidized sand 1 hour after preparation. It can be seen that the penetration stress of is improved to 5,948 (Pa), that is, about 6,000 (Pa) or less.

Further, from the flow test results of FIG. 9, it can be seen that the fluctuation of the table flow value (mm) depending on the presence or absence of mixing of HIDS is hardly observed, and the influence of the fluidized sand on the table flow value can be ignored. In the case of the organic charge neutralizer, either a method of mixing it with the material sand in a powder state or a method of mixing it with the material sand in a state of being dissolved in water may be used as in the case of the inorganic charge neutralizer. Generally, the latter method is preferable from the viewpoint of uniform mixing. In this case, the water used will be treated as a part of the water content adjusting water.

Example 7: In FIG. 10, 0 ppm, 600 ppm, 1200 ppm, and 2400 ppm of ethylenediaminetetraacetic acid tetrasodium tetrahydrate (hereinafter referred to as Kirest OD) are mixed as an organic charge neutralizer with a predetermined amount of material sand. After that, the results of a texture test (hardness) of four types of fluidized sand prepared by mixing water for adjusting the water content ratio, a fluidizing agent, and a slow-acting plasticizing agent at a predetermined ratio are shown. There is. In the figure, the composition of Kirest OD, which is an organic charge neutralizer, is 0 ppm for black circles, that is, a sample not mixed, a sample with 600 ppm for squares, a sample with 1200 ppm for white circles, and a sample with 2400 ppm for triangles. From this test result, the penetration stress is significantly smaller than that of the conventional sample not mixed with Chelest OD even if only 600 ppm is mixed. In other words, for example, looking at the change over time 1 hour after preparation, the change in properties is suppressed to 16,128 (Pa) when 600 ppm of Chelest OD is mixed with 16,380 (Pa) when no additives are added. The point that the reference value, that is, the penetration stress of the fluidized sand 1 hour after preparation is improved to 4,877 (Pa) or less by mixing 1200 ppm of chillest OD, and the penetration stress is 600 ppm of chillest OD mixed. It can be seen that there is not much change between the case and the case where 2400 ppm is mixed. Although the flow test was omitted, as in Example 1, the table flow value (mm) did not fluctuate depending on the presence or absence of sodium carbonate mixing, and the effect of the fluidized sand on the table flow value was negligible. ..

The above embodiments and examples do not limit the present invention in any way. The present invention may be I comprise technical elements specified by the claims, details Ru der capable variously modified as necessary.

1 ・ ・ ・ ・ ・ Construction machine 2 ・ ・ ・ ・ ・ Fluidized sand production plant 3 ・ ・ ・ ・ ・ Hollow pipe 4 ・ ・ ・ ・ ・ Elevating mechanism 5 ・ ・ ・ ・ ・ Rotating hand mechanism 6 ・ ・ ・・ Pressure gauge 7 ・ ・ ・ ・ ・ Material sand 8 ・ ・ ・ Liquid injection pipe 9 ・ ・ ・ Improved body 15 ・ ・ ・ Swivel 16 ・ ・ ・ ・ ・ Pipe line 24 ・ ・ ・ ・ ・ Ion Charge neutralizing additive supply means 25 ・ ・ ・ ・ ・ Flowing agent supply means 26 ・ ・ ・ ・ ・ Adjustment water supply means 27 ・ ・ ・ ・ ・ Plastic agent supply means

Claims (4)

In the method for producing fluidized sand for ground improvement, which is processed by adding a fluidizing agent together with water for adjusting the water content ratio to the material sand and transferring it through a pipe by a pressure pump.
An additive for ionic charge neutralization is added to a predetermined amount of the material sand so that the cations such as metal ions contained in the material sand, which are obstacles to the fluidizing agent, can be charge-neutralized with respect to the material sand. , was mixed 100Ppm～1000ppm, manufacturing method of fluidized sand, characterized by mixing said fluidizing agent. The method for producing fluidized sand according to claim 1, wherein the additive for ionic charge neutralization is an inorganic charge neutralizing agent such as sodium carbonate, sodium tripolyphosphate, and sodium hexametaphosphate. The first aspect of claim 1 is that the additive for ionic charge neutralization is an organic charge neutralizing agent such as 3-hydroshiki-2,2'-iminodicosuccinate tetrasodium, ethylenediamine tetraacetate tetrasodium tetrahydrate. The method for producing fluidized sand according to the above. The method for producing fluidized sand according to any one of claims 1 to 3, wherein the fluidized sand has a penetration stress of about 6,000 (Pa) or less after at least 1 hour of preparation from the texture test. ..

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