Filler manufacturing method and filler

Abstract

To manufacture a filler that can control water permeability after filling while ensuring fluidity.SOLUTION: A method for manufacturing a filler containing an additive solution containing a dissolved polymer additive and a granular material comprises a particle size adjustment step of adjusting a particle size of the granular material based on water permeability required of the filler after filling voids, a viscosity acquisition step of acquiring a target viscosity of the additive solution capable of retaining the granular material based on a maximum particle size of the granular material whose particle size has been adjusted, a concentration selection step of selecting the concentration of the additive solution based on the obtained target viscosity, and an addition amount setting step of setting the amount of addition of the additive solution prepared at the selected concentration to the granular material based on a flowable gap ratio of the granular material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a filler for filling voids in the ground, and a filler manufactured by the method for manufacturing a filler. [Background technology]

[0002] For example, when excavating ground using the cut-and-cover method, a retaining wall is constructed to surround the planned excavation area to prevent the collapse of surrounding soil and to stop water leakage. Retaining walls constructed using retaining materials such as steel sheet piles and steel pipe sheet piles are prone to voids at the joints of the sheet piles, steel pipe sheet piles, and steel pipe piles, which can lead to defects caused by the voids. Furthermore, these are generally removed after construction is completed, but this can have a significant impact on the surrounding ground depending on the ground conditions, such as the risk of ground subsidence due to voids created in the ground or loosening of the ground during removal.

[0003] For this reason, filler materials are often used to fill the voids left by the removed earth-retaining members. For example, Patent Document 1 discloses a construction method in which a hardening agent is used as a filler and injected into the voids left by the removed earth-retaining members. Specifically, hardening agent injection pipes are installed at predetermined intervals adjacent to the earth-retaining members cast into the ground. Then, when the earth-retaining members are removed, the hardening agent is filled into the voids while the hardening agent injection pipes are being removed along with the earth-retaining members. A similar construction method is also used to fill hardening agents into joints in sheet piles, steel pipe sheet piles, and steel pipe piles. By employing this hardening agent filling method, it is possible to minimize the impact on the surrounding ground that may occur due to voids in the voids left by the removed earth-retaining members, voids in the joints of sheet piles, steel pipe sheet piles, and steel pipe piles, or voids or loosening of the ground that may occur in the voids left by the removed earth-retaining members. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3940735 Summary of the Invention [Problem to be solved by the invention]

[0005] The work of filling voids that have occurred in the ground with filler materials, such as those mentioned above, is not limited to joints or extraction holes of retaining members, but is carried out for all types of voids in the ground. When filling any type of void, the resulting void must have the same compressive strength as the surrounding ground. For this reason, liquefied treated soil, which ensures fluidity and easily develops strength, is often used. However, liquefied treated soil has various issues, such as being expensive to procure and increasing the environmental impact due to the use of cement-based solidification materials. Furthermore, because it is difficult to control permeability, it cannot be used in environments where the resulting void must have not only compressive strength but also permeability equivalent to the surrounding ground.

[0006] In this context, water- and air-permeable fillers made by mixing gravel, sand, water, and other materials with non-cement-based superplasticizers are being considered. However, the mixing process can be complicated and time-consuming, and depending on the materials used, sufficient fluidity may not be achieved, making pumping the filler or pouring it using a tremie pipe difficult. In such cases, a method of directly dropping the filler into the voids is considered, but this poses issues with workability, such as the risk of the filler separating in the water if the voids are filled with groundwater or other substances.

[0007] The present invention has been made in view of the above problems, and its main object is to produce a filler that can control the water permeability after filling while ensuring fluidity. [Means for solving the problem]

[0008] In order to achieve this purpose, the filler filling method of the present invention is a method for manufacturing a filler containing an additive solution in which a polymer additive is dissolved and granular material, and is characterized by comprising: a particle size adjustment process for adjusting the particle size of the granular material based on the water permeability performance required of the filler after filling the voids; a viscosity acquisition process for acquiring a target viscosity of the additive solution capable of holding the granular material based on the maximum particle size of the granular material whose particle size has been adjusted; a concentration selection process for selecting the concentration of the additive solution based on the acquired target viscosity; and an addition amount setting process for setting the amount of the additive solution prepared to the selected concentration to be added to the granular material based on the flowable void ratio of the granular material.

[0009] The filler filling method of the present invention is characterized in that the target viscosity of the additive solution is obtained by calculating the shear stress capable of holding particles of the largest particle size among the granular material whose particle size has been adjusted, and converting the calculated shear stress into viscosity.

[0010] The method for filling a filler of the present invention is characterized in that the shear rate of the additive solution having the shear stress is set using a B-type viscometer, and the shear stress is converted into viscosity by dividing the shear stress by the shear rate corresponding to the expected flow speed of the filler.

[0011] The method for filling a filler according to the present invention is characterized in that the shear rate is measured at a rotation speed of 6 rpm.

[0012] The method for filling a filler of the present invention is characterized in that the amount of the additive solution added is set to more than 0.65 times and not more than 0.91 times the volume of the granular material.

[0013] The filler of the present invention is a filler for filling voids, and is characterized by being produced by the filler production method of the present invention.

[0014] According to the filling method and filler of the present invention, the concentration of the additive solution is selected based on the target viscosity at which the granular material can be retained, and the additive solution prepared to the selected concentration is added to the granular material to an extent that maintains a void ratio that allows the granular material to flow. This allows the filler to flow freely within the voids, filling every corner.

[0015] Furthermore, after a certain time has passed, the granular material remains in the voids and the viscosity of the additive solution disappears, a phenomenon similar to water compaction. In other words, the permeability of the voids becomes almost the same as when the granular material is densely packed. Therefore, by adjusting the particle size of the granular material in advance according to the permeability required of the filler after filling the voids, it is possible to control the permeability of the filler and achieve the desired permeability (low permeability to high permeability).

[0016] Furthermore, the shear rate of the additive solution used to convert shear stress to viscosity is measured using a B-type viscometer at a rotation speed of 6 rpm. This measurement method is similar to the method used to determine the properties of the stabilizing liquid (bentonite solution) used to protect the walls of underground boreholes, and makes it possible to more accurately determine the properties of the additive solution.

[0017] In addition, the granular material can be made from materials commonly used as fillers, such as soil materials, locally generated soil, or grading agents, and polymer additives can be selected appropriately depending on the desired performance of the filler. This makes it possible to easily manufacture fillers that are suited to the shape of voids and their intended use. [Effects of the Invention]

[0018] According to the present invention, an additive solution containing a polymer additive dissolved in a filler and granular material are used, and the viscosity of the additive solution is set to a level that can hold the granular material.The amount of additive solution added is also set based on the void ratio that allows the granular material to flow, making it possible to control the permeability after filling while ensuring the fluidity of the filler. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a diagram showing an outline of a filler according to the present embodiment. [Figure 2] 2 is a flow chart showing a method for manufacturing a filler according to the present embodiment. [Figure 3] 1 is a table showing the relationship between 20% particle size (D20) and permeability coefficient k according to Creager in this embodiment (from "Revised Groundwater Handbook," published by Construction Industry Research Institute, August 1, 1998, p. 290), and a graph showing the relationship between clay and concentration. [Figure 4] 1 is a diagram showing a three-dimensional structure made of granular material in this embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention relates to a mortar-like filler material in which granular material is held in an additive solution, and to a method for manufacturing the same.The filler material is given fluidity, allowing it to fill every corner of the voids, and after filling, the additive solution is removed, allowing the remaining granular material to exhibit water permeability based on the particle size.

[0021] The method for producing a filler material of the present invention and the filler material produced by this production method will be described in detail below with reference to Figures 1 to 4. In this embodiment, an example will be described in which a borehole (void portion) formed in the ground by open-cut work is backfilled with a filler material.

[0022] ≪≪Filling material≫≫ As shown in Figure 1(a), a void H in the ground is filled and backfilled with a filler material 1. The filler material 1 is a mixture of granular material 11 and an additive solution 12, and the additive solution 12 is a solution in which a polymer additive 2 is dissolved.

[0023] Any water-soluble polymer may be used as the polymer additive 2, and examples thereof include carboxymethyl cellulose (CMC), polyacrylamide copolymers, sodium polyacrylate, etc., which are used as additives for stabilizing solutions for pile construction and diaphragm wall construction, etc., and for stabilizing solutions for shield construction and jacking construction, etc. A single material of these may be used as the polymer additive 2, or a plurality of materials may be used in appropriate combination.

[0024] Furthermore, any material commonly used as a filler, such as soil material, construction waste soil (including soil generated on-site), or grain size adjuster, can be used as the granular material 11. When using construction waste soil, it is desirable to use recycled sand that has been washed with water and classified at an intermediate treatment facility, but dry sand or wet sand with a low clay content can also be used.

[0025] <<Filler manufacturing method>> The filler 1 made of the above materials can be produced by the following procedure, which will be described in detail below with reference to the flow chart shown in FIG.

[0026] ≪STEP1: Particle size adjustment process≫ First, the particle size of the granular material 11 is adjusted based on the water permeability required for the filler material 1 after filling the voids H as shown in FIG.

[0027] The Creager method is used to adjust the particle size of the granular material 11 based on the permeability. Specifically, a 20% particle size (D20) that satisfies the permeability required of the filler 1 after filling the voids H is selected from a table of the relationship between the 20% particle size (D20) of samples prepared by Creager and the permeability coefficient k, as shown in Figure 3(a). Then, the particle size of the granular material 11 is adjusted based on the selected 20% particle size (D20).

[0028] ≪STEP2: Viscosity acquisition process≫ Next, based on the maximum particle size of the particle size-adjusted granular material 11, a target viscosity of the additive solution 12 capable of holding the granular material 11 is obtained. The target viscosity of the additive solution 12 is obtained by calculating the shear stress S capable of holding particles of the maximum particle size among the particle size-adjusted granular material 11, and then converting this shear stress S into viscosity.

[0029] The shear stress S of the additive solution 12 can be calculated by the following formula (1). JPEG0007791522000001.jpg39170

[0030] The particle density ρs can be calculated from the particle weight and particle volume. The density ρτ of the additive solution 12 can be considered to be approximately 1.0, for example, when the density of the polymer additive 2 used is about 1.5.

[0031] Next, a test additive solution 12 having the above shear stress is prepared, and the shear rate of the test additive solution 12 (the shear rate corresponding to the expected flow rate of the filler 1) is measured using a B-type viscometer. The shear rate measurement is preferably performed at a rotation speed of 6 rpm. This is the same condition as that used when determining the properties of a stable liquid, and makes it possible to more accurately determine the properties of the additive solution 12. After this, the shear stress S calculated by the above equation (1) is divided by the measured shear rate to convert it into viscosity, thereby obtaining the target viscosity.

[0032] ≪STEP3: Concentration selection process≫ The concentration of the additive solution 12 is selected based on the target viscosity obtained in STEP 2. Generally, in a solution of a polymer compound, there is a relationship between viscosity and concentration as shown in Figure 3(b), and it is widely known that the viscosity of the solution is adjusted by adjusting the concentration.

[0033] Therefore, a plurality of additive solutions 12 with different concentrations of polymer additive 2 dissolved therein are prepared in advance, and the viscosity of each is measured. Next, a relational expression between the concentration and viscosity of the additive solution 12 using polymer additive 2 is prepared from the relationship between the concentration and the corresponding viscosity. Then, the concentration is calculated by substituting the target viscosity of the additive solution 12 calculated previously.

[0034] ≪STEP 4: Addition amount setting process≫ After selecting the concentration of the additive solution 12 in the concentration setting process, the amount of the additive solution 12 prepared to the selected concentration to be added to the granular material 11 is set based on the void ratio that allows the granular material 11 to flow.

[0035] As shown in Figure 4, assuming that the particles constituting the granular material 11 are spherical and of equal size, if the granular material 11 is stacked in a so-called close-packed state, it will be unable to move and will not be able to flow. However, it is generally known that the granular material 11 will flow if it is stacked in a square loose packing or a mixture of square loose packing and hexagonal loose packing. Furthermore, even if it is stacked in a hexagonal loose packing, the granular material 11 can flow under certain conditions (for example, when the shape of the granular material 11 is close to a sphere). It is also known that the void ratio (void volume / granular material volume) of hexagonal loose packing is 0.654, and the void ratio of tetragonal loose packing is 0.910.

[0036] Therefore, in order to maintain the void ratio of the granular material 11 at least 0.654 or more, preferably 0.910 or more, the amount of additive solution 12 added is set to at least 0.65 times, preferably 0.91 times, the volume of the granular material 11.

[0037] ≪STEP5: Liquid preparation process≫ The additive solution 12, prepared to the concentration selected in the concentration selection step, is added to the granular material 11, the particle size of which has been adjusted in the granular material selection step, in the amount set in the amount setting step to prepare the filler 1. As an alternative manufacturing method, instead of preparing the additive solution 12 in advance from the powdered polymer additive 2, the polymer additive 2 and the granular material 11, the particle size of which has been adjusted, are powder-blended, and then a measured amount of water is added so that the polymer additive 2 reaches a predetermined concentration, followed by stirring. This method also makes it easy to manufacture the filler 1.

[0038] <Filler performance: high fluidity> In the filler 1 produced by the above procedure, the additive solution 12 has a viscosity sufficient to hold the granular material 11, and has such a high surface tension that a small amount of it adheres to the surface of the granular material 11 and moves together. Such additive solution 12 with high surface tension tends to become spherical, and when it adheres to granular material 11 with a diameter of about 1 cm, it can be approximated as a sphere. As mentioned above, the amount of additive solution 12 added to the granular material 11 is set to an amount sufficient to maintain a void ratio that allows the granular material 11 to flow.

[0039] This allows the filler 1 to have high fluidity and fill every corner of the voids H. If it is desired to temporarily increase the fluidity, foamed air like shaving cream may be added to the filler 1. Therefore, any filling method can be used, such as pumping, pouring using a tremie pipe, or direct dropping.

[0040] <Filler performance: No separation in water> Furthermore, when the filler 1 is dropped directly into a void H filled with groundwater, for example, it is dropped near the bottom of the void H. In this way, the filler 1 is gradually deposited while being pushed along the bottom without separating in the water, making it possible to fill every corner of the void H. As mentioned above, this is because the additive solution 12 has such an extremely high surface tension that a small amount of the filler is adsorbed to the surface of the granular material 11 and moves together. In this embodiment, the non-separability in water refers to the degree to which the filler 1, after being dropped into water, deposits at the bottom of the void H and forms a level state.

[0041] <Filling material performance: water permeability> Furthermore, as shown in Figure 1(b), after filling the voids H, the additive solution 12 of the filler 1 disappears over time, leaving only the granular material 11. In other words, a phenomenon similar to water tightening occurs within the voids H, resulting in the granular material 11 being densely packed. Therefore, the permeability required of the filler 1 after filling the voids H is approximately the same as the permeability when the granular material 11 is densely packed.

[0042] For this reason, in the above-mentioned granular material selection process, the particle size of the granular material 11 is adjusted according to the water permeability required of the filler material 1 after it has been filled into the voids H. This allows the filler material 1 after it has been filled into the voids H to be freely controlled from low water permeability to high water impermeability.

[0043] The method of controlling the water permeability of the filler 1 by adjusting the particle size of the granular material 11 is not limited to the Creager method, and various empirical formulas that have been proposed as means for estimating the water permeability coefficient from particle size composition information may be appropriately selected and adopted. Also, when the voids H are in the atmosphere (higher than the groundwater), the air permeability of the filler 1 can be controlled.

[0044] As described above, the filler material 1, which can be used with any filling method and whose permeability can be controlled from low to high permeability, can be applied to a variety of voids H and uses. Examples of possible uses include filling holes in the ground formed by open-cut construction, gravel packing for emergency wells, filling material for geothermal wells, permeable filling material or water-stopping filling material for aquifers, filling additives (improving thermal conductivity with shot blasting), water-stopping material for joints in steel pipe piles, temporary strength-increasing filling material, filling material for collapsed ground, filling material inside chambers at the start of mud-adding shield construction, and filling voids left behind after sheet piles have been pulled out.

[0045] <Filler performance: Long-distance pumpability> Furthermore, the filler material 1 can be used not only for voids H that are large in the depth direction, but also for voids H that are wide in the horizontal direction, such as the hollow part of a long underground pipe.When filling the hollow part of an underground pipe, it is advisable to add an anti-deterioration agent to the filler material 1.

[0046] Examples of anti-deterioration agents that can be used include organic amines, triazines, cyclic nitrogen sulfur compounds, and cyclic nitrogen composites. For example, if a material primarily composed of CMC, which is widely used as a shielding mud additive, is used as the polymer additive 2 in filler 1, filler 1 will lose its fluidity within a few days to a few weeks. However, by adding an anti-deterioration agent, the fluidity of filler 1 can be maintained for a long period of time (e.g., several weeks to several months). Therefore, filler 1 can be reliably filled even when the hollow portion of the underground pipe to be filled is long distances.

[0047] <Filler performance: Non-deformable, long-distance pumpability> Furthermore, after filling the voids H, the additive solution 12 gradually disappears from the filler 1, but this does not involve any reaction such as heat generation. Also, when it disappears, a phenomenon similar to water compaction occurs, and only the dense granular material 11 remains, and not only does it not deform over time or change in volume due to aging, but the adhesive component remaining in the filler also bonds the particles together, preventing liquefaction during an earthquake.

[0048] Furthermore, since it is possible to develop an unconfined compressive strength (approximately 0.2 to 0.5 N / mm2) similar to that of the ground, it is also possible to re-excavate the ground after filling the voids. In this case, it is recommended to use, as the polymer additive 2 used in the filler 1, for example, nonionic methyl cellulose (MC) or hydroxy(propyl)ethyl cellulose (HEC), or weak anionic acrylamide, and then add a cement-based hardener to the filler 1.

[0049] As described above, the manufacturing method of the filler 1 makes it possible to manufacture a filler 1 that can control the water permeability after filling while maintaining fluidity. Furthermore, because the additive solution 12 contains the polymer additive 2 dissolved therein, it will not decay and generate flammable gases. Furthermore, compared to using a cement-based hardening agent, such as in liquefied treated soil, it is possible to significantly reduce the environmental impact.

[0050] The manufacturing method of the filler 1 and the filler 1 of the present invention are not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0051] 1 Filler 11 Granular materials 12 Additive solution 2 Polymer additives H void area

Claims

1. A method for producing a filler material comprising an additive solution in which a polymer additive is dissolved and a granular material, a particle size adjusting step of adjusting the particle size of the granular material based on the water permeability required for the filler after filling the voids; a viscosity acquisition step of acquiring a target viscosity of the additive solution capable of retaining the granular material based on the maximum particle size of the granular material whose particle size has been adjusted; a concentration selection step of selecting a concentration of the additive solution based on the acquired target viscosity; an addition amount setting step of setting an addition amount of the additive solution prepared to a selected concentration to the granular material based on a flowable void ratio of the granular material; A method for producing a filler, comprising:

2. The method for producing a filler according to claim 1, A method for manufacturing a filler, characterized in that the target viscosity of the additive solution is obtained by calculating the shear stress capable of holding the largest particle size among the granular material whose particle size has been adjusted, and converting the calculated shear stress into viscosity.

3. The method for producing a filler according to claim 2, A method for producing a filler, comprising: setting a shear rate of the additive solution having the shear stress using a B-type viscometer; and converting the shear stress into viscosity by dividing the shear stress by a shear rate corresponding to an expected flow velocity of the filler.

4. The method for producing a filler according to claim 3, A method for producing a filler, characterized in that the shear rate is measured under the condition of a rotation speed of 6 rpm.

5. In the method for producing a filler according to any one of claims 1 to 4, A method for producing a filler, characterized in that the amount of the additive solution added is set to be more than 0.65 times and not more than 0.91 times the volume of the granular material.

6. A filler for filling voids, characterized in that the filler is produced by the method for producing a filler according to any one of claims 1 to 5.

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