Method for determining the composition of a plastic grout material

Abstract

To provide a method for determining adequate compositions of the plastic grout material having properties suitable for each of construction sites.SOLUTION: A composition determination method of plastic grout material of the present invention comprises the steps of: measuring properties (e.g. grain size distribution, porosity n, and the like) of the constructed ground (e.g. boulder ground); calculating yield strength (τy) based on measured properties of the constructed ground; and determining compositions of the plastic grout material meeting a calculated yield strength (τy).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for determining the formulation of a plastic grout material.

Background Art

[0002] The term "plastic" in a plastic grout material means a property that exhibits fluidity when a shearing force is applied and does not exhibit fluidity when no shearing force is applied. The plastic grout material is considered to correspond to a Bingham fluid as a rheological property and has water non-separability and low shrinkage. The plastic grout material is used, for example, as an injection material to be injected into voids, joints, cracks of the ground or structures, or gaps formed between the ground and structures, or as a filling material in the construction back cavity of an existing tunnel (see, for example, Patent Document 1). The plastic grout material may be used to fill the gaps between boulders such as riprap mounds constructed as the foundation of a revetment. Such cases include cases where construction is carried out for the purpose of seismic reinforcement of a revetment, etc., and cases where construction is carried out to partially and limitedly improve a part of the riprap mound.

[0003] When filling the gaps between boulders with a plastic grout material, it is ideal for the plastic grout material to spread concentrically (or spherically) from the discharge port of the injection pipe and be filled. By filling the grout material concentrically (or spherically) from the discharge port of the injection pipe, it becomes possible to limit the filling to, for example, the improvement range required for seismic reinforcement, and prevent filling into an unnecessary range (outside the required improvement range).

[0004] However, in filling the gaps between boulders, if a grout material with high fluidity is used with respect to the size of the boulders, the grout material will flow downward due to its own weight, so it is impossible to perform filling that stays in a predetermined area. And in filling in boulder ground, the required properties of the grout material differ corresponding to the size of the boulders in the construction ground. Therefore, it is necessary to determine the appropriate formulation of the plastic grout material for each construction site. However, conventionally, such a formulation determination technique has not been proposed, and the determination of the formulation of the plastic grout material has relied on the experience of the workers, or it has been necessary to carry out test construction with multiple formulations set for each construction site to determine the formulation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been proposed in view of the problems of the above-described conventional technologies, and an object thereof is to provide a method capable of appropriately determining the formulation of a plastic grout material having properties corresponding to each construction site.

Means for Solving the Problems

[0007] The method for determining the formulation of the plastic grout material of the present invention comprises a step of measuring the properties (for example, particle size distribution, void ratio n, etc.) of the ground to be constructed (for example, boulder ground), from the measured properties of the ground to be constructed Of the plastic grout material a step of calculating the yield stress (τy), the calculated Of the plastic grout material a step of determining the formulation of the plastic grout material that satisfies the yield stress (τy). and The ground to be constructed is a gravel ground, and the properties of the measured gravel ground are the particle size distribution (for example, the 50% particle size D representing the average size of the large gravel 50 or the 10% particle size D 10 ), and the porosity (n), replacing the gravel (1) with a cube having equal side lengths and having an annularly missing portion, and calculating the yield stress (τy) using a model in which the gaps between the gravels (1) are replaced with a combination of a plurality of circular pipes (2) of the same diameter (d) (or a network of circular pipes 2).

[0009] Also, the present invention The method for determining the composition of the plastic grout material includes a step of measuring the properties (for example, particle size distribution, porosity n, etc.) of the ground to be constructed (for example, large gravel ground), a step of calculating the yield stress (τy) of the plastic grout material from the measured properties of the ground to be constructed, and a step of determining the composition of the plastic grout material that satisfies the calculated yield stress (τy) of the plastic grout material. In the initial stage of calculating the yield stress (τy), the density (ρ g ) of the plastic grout material is assumed to be the density of the standard formulation of the plastic grout material to be formulated (for example, 1.8), and Of the plastic grout material the yield stress (τy) is calculated, and the calculated Of the plastic grout material formulation of the plastic grout material that satisfies the yield stress (τy) (a formulation having a yield stress τy equal to or greater than the calculated yield stress τy A ) is selected, Determine the yield stress (τy A ) of the selected plastic grout material, the actual density of the selected plastic grout material is determined, the yield stress (τy re) is recalculated using the determined actual density, the recalculated yield stress (τy re) is compared with the yield stress (τy A ) of the selected plastic grout material, and if the recalculated yield stress (τy re) is less than or equal to the yield stress (τy A ) of the selected plastic grout material, the formulation that satisfies the initially calculated yield stress (τy) is determined as the formulation of the plastic grout material, if the recalculated yield stress (τy re) is greater than the yield stress (τy A ) of the selected plastic grout material, the formulation of the plastic grout material that satisfies the initially calculated yield stress (τy) is determined again, Determine the yield stress (τy A re) of the plastic grout material whose composition has been determined again, the actual density of the plastic grout material whose formulation has been determined again is determined, the actual density of the plastic grout material whose formulation has been determined again is determined, and using the determined actual density, Of the plastic grout material whose composition has been determined again the yield stress (τy re re) is recalculated (recalculated again), and it is preferable to compare the recalculated yield stress (τy re re) with the yield stress (τy A re) of the plastic grout material whose formulation has been determined again. And if the recalculated yield stress (τy re re) is the yield stress (τy AIn the following cases, the determined formulation of the plastic grout material after re-determination is determined as the formulation of the plastic grout material. On the other hand, when the re-calculated yield stress (τy_re-re) is greater than the yield stress (τy_re) of the plastic grout material for which the formulation was re-determined, the formulation of the plastic grout material that satisfies the initially calculated yield stress (τy) is re-determined, and the above-described steps are repeated. A When it is greater than (τy_re), the formulation of the plastic grout material that satisfies the initially calculated yield stress (τy) is re-determined, and the above steps are repeated. Here, when determining the density of the plastic grout material, it can be carried out by methods such as actually measuring the density of the actually manufactured plastic grout material or calculating from the densities of the individual materials to be formulated. Also, the yield stress (τy A ) of the plastic grout material initially selected and the yield stress (τy A _re) of the plastic grout material for which the formulation was re-determined are measured by existing measurement techniques, for example, using instruments such as a rotational viscometer, a ball-pulling-up viscometer, a parallel plate plastometer, etc., or by converting from the results of consistency tests such as a slump test and a flow test, or other methods, and are always measured when determining the formulation.

[0010] Also, the method for determining the composition of the plastic grout material of the present invention includes a step of measuring the properties (for example, particle size distribution, porosity n, etc.) of the ground to be constructed (for example, large gravel ground), a step of calculating the yield stress (τy) of the plastic grout material from the measured properties of the ground to be constructed, and a step of determining the composition of the plastic grout material that satisfies the calculated yield stress (τy) of the plastic grout material. The ground to be constructed is a gravel ground, and the properties of the measured gravel ground are the particle size distribution (for example, the 50% particle size D representing the average size of the large gravel 50 or the 10% particle size D 10 ), and the porosity (n), calculating the yield stress (τy) using a model in which the gravel (1) is replaced with a cube having equal side lengths and having an annularly missing portion, and the gaps between the gravels (1) are replaced with a combination of a plurality of circular pipes (2) of the same diameter (d) (or a network of circular pipes 2), Let the length (L) of one side of the cube of the model be the 50% particle size (D 50 : corresponding to the median) of the average boulder size. which is characterized by. Or the method for determining the composition of the plastic grout material of the present invention includes a step of measuring the properties (for example, particle size distribution, porosity n, etc.) of the ground to be constructed (for example, large gravel ground), a step of calculating the yield stress (τy) of the plastic grout material from the measured properties of the ground to be constructed, and a step of determining the composition of the plastic grout material that satisfies the calculated yield stress (τy) of the plastic grout material. The ground to be constructed is gravel ground, and the properties of the gravel ground to be measured are the particle size distribution (e.g., the 50% particle size D representing the average size of boulders50 or the 10% particle size D 10 ) and the porosity (n). When calculating the yield stress (τy) using a model in which gravel (1) is replaced with a cube having equal side lengths and having an annularly missing portion, and the gaps between gravel (1) are replaced with a combination of a plurality of circular pipes (2) of the same diameter (d) (or a network of circular pipes 2). The length (L) of one side of the cube of the model is 10% of the particle size (D 10 ). It is characterized by this. In the present invention, when calculating the yield stress (τy) using a model in which gravel (1) is replaced with a cube having equal side lengths and having an annularly missing portion, and the gaps between gravel (1) are replaced with a combination of a plurality of circular pipes (2) of the same diameter (d) (or a network of circular pipes 2). Regarding the length (L) of one side of the cube of the model, it is preferable to obtain the length (L) of one side of the cube by calculation so that the volume of the boulder and the volume of the cube are equivalent.

Advantages of the Invention

[0011] According to the method for determining the composition of the plastic grout material of the present invention having the above-described configuration, the yield stress (τy) is calculated from the properties of the ground to be constructed (for example, particle size distribution, porosity n, etc.), and the composition of the plastic grout material is determined so as to satisfy the calculated yield stress (τy). Therefore, the composition can be determined based on objective criteria (parameters). Therefore, compared with the method of determining the composition of the plastic grout material relying on conventional experience or the method of determining the composition by setting a plurality of compositions for each construction site and performing test construction, a more appropriate composition can be objectively and easily determined. And by using the information (data) on the plastic grout material and its yield stress (τy) in the past, the composition of the plastic grout material suitable for each construction site can be determined.

[0012] The conditions vary for each construction site, or even at the same construction site, the sizes and shapes of individual gravels are different. Therefore, the calculation of the yield stress (τy) may be very complicated and difficult to understand. However, according to the present invention, a model is used in which gravel is replaced with cubes of the same size, and the gaps between gravels are replaced with a combination of a plurality of circular pipes of the same diameter (or a network of circular pipes). As a result of using such a model, various parameters necessary for determining the yield stress (τy) and the yield stress (τy) can be easily calculated using commercially available spreadsheet software (for example, the product name "Excel" of Microsoft). Therefore, various costs related to composition determination can be kept low.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In FIG. 1 showing the procedure in the method for determining the composition of the plastic grout material according to the illustrated embodiment, in step S1, the properties of the ground to be constructed (target ground), for example, the particle size distribution of boulders (for example, the 50% particle size D which is the average size of boulders 50 or the 10% particle size D 10 ) and the porosity n are grasped by measurement, investigation, etc. The particle size distribution and void ratio n of the boulders obtained through measurement, investigation, etc. in step S1 are data necessary for calculating the diameter d of the model circular pipe and the yield stress τy of the target ground in subsequent processes, and are basic data for determining the formulation of a plastic grout material with properties adapted to the construction site.

[0015] In step S2 following step S1, the boulder ground, which is the target ground, is converted into a model in which the gaps between the boulders 1 are replaced by circular pipes 2 arranged at equal intervals with a diameter dimension d, and the boulders 1 are replaced by cubes. That is, the boulder ground having the boulders 1 and the gaps C shown in Fig. 2 is converted into a model composed of the circular pipes 2 arranged at equal intervals d and the boulders 1 consisting of cubes of a single shape and size, as shown in Fig. 3. In Fig. 2, the circular pipes 2 are represented by the blanks between the boulders 1, and the cubes constituting the boulders 1 are represented by squares.

[0016] The model shown schematically in Fig. 3 is shown in detail in Fig. 4. In Fig. 4, the network of the circular pipes 2 with a plurality of pipe diameters d shown in Fig. 4(1) models and displays the gaps in the boulder ground. In Fig. 4(1), a plurality of boulders 1 constituting the bedrock ground are displayed three-dimensionally, and the gaps between the respective boulders 1 are taken as circular pipes 2 (diameter dimension d: Fig. 3). In Fig. 4(1), the circular pipes 2 constituting the network are shown, but the boulders 1 are not clearly shown. The circular pipes 2 extend in the three-dimensional direction between the respective boulders 1. As shown in Fig. 4(2), in the above-described model, the shape of the boulders 1 is approximately cubic, and it is converted into a model in such a shape that all its sides (12 sides) are removed by the circular pipes 2 with a diameter d. Also, Fig. 4(2) shows the space other than the gaps in the boulder ground (the portions of the circular pipes 2 with a diameter d) as a plurality of boulders 1. And Fig. 4(3) shows a single boulder 1 among the plurality of boulders 1 shown in Fig. 4(2).

[0017] In step S3 following step S2 in Fig. 1, based on the model of the boulder ground replaced in step S2 (see Figs. 4(1) to 4(3)), the 10% particle size D 10From the porosity n and the diameter d of the circular pipe in the model of Fig. 4, the diameter d of the circular pipe in the model of Fig. 4 is calculated. Here, the 10% particle size D is used as the size of the gravel, but the 50% particle size D representing the average size of the boulders can also be used. 10 is used, but the 50% particle size D representing the average size of the boulders can also be used. 50 can also be used.

[0018] When the gaps between the boulders are modeled as a network of circular pipes 2 with diameter d as shown in Fig. 4, the shape of a single gravel 1 shown in Fig. 4(3) is modeled as a shape obtained by subtracting the volume of the part of the circular pipe 2 with diameter d (a columnar body having a cross-sectional area of a quarter circle of a circle with diameter d) from a cube with side length L on all sides (12 sides), as shown in Figs. 5(1) to 5(3). In Fig. 5, the circular pipe 2 (a columnar body having a cross-sectional area of a quarter circle of a circle with diameter d) is the missing part M. In Fig. 5(1), the circular pipe part (missing part M) missing from the cube with side length L forms a circle with diameter d when the four corner missing parts M are combined, as shown in Fig. 5(2) which is the cross-sectional view of Fig. 5(1), or as shown in Fig. 5(3) which simplifies a single gravel 1. Here, the ratio of the volume of the missing part of the cube (cube with side L) by the circular pipe 2 with pipe diameter d to the volume of the cube with side length L corresponds to the porosity n of the boulder ground.

[0019] In the boulder model of Fig. 5, when the side length of the boulder 1 is L and the diameter of the circular pipe 2 is d, the volume of the missing part M is as follows. M = 3L(πd 2 / 4) - 2×(2 - 2 1 / 2 )d 3 [1] The volume of the boulder 1 is equivalent to the volume of a cube with side length L through which three circular pipes 2 with diameter d pass. Since the three circular pipes 2 overlap at the center of the cube, the volume of the missing part M is the value obtained by subtracting the volume of the overlapping edge part {(2 - 2 1 / 2 )d 3 ×2} from the volume of the three circular pipes 2. And since the porosity n of the model ground is the ratio (for example, in percentage) of the volume of the missing part M to the volume of the cube with side length L, it becomes the following formula [2]. n = (M / L 3)×100 [2] When equations [1] and [2] are transformed, the following equation [3] is obtained. n / 100 = (3π / 4)(d 2 / L 2 ) - 2×(2 - 2 1 / 2 )d 3 / L 3 [3] Equation (3) is a cubic equation with "d / L" as the variable. If the value of the void ratio n is determined (measured in step S1), then "d / L" can be easily obtained by solving the cubic equation of equation [3] using, for example, the calculation function of spreadsheet software.

[0020] Also, since the volume V of each boulder is the value obtained by subtracting the volume of the missing part M from the volume of a cube with side length L, it is expressed by the following equation [4]. V = L 3 - M [4] From equations [2] and [4], the following equation [5] is obtained. (V / L 3 ) = 1 - (n / 100) [5] If the volume V in equation [5] is considered to be equivalent to the volume of a boulder 1 with a diameter equal to the representative particle size of the ground (for example, the 10% particle size D 10 ), then based on the value of V obtained from the value of the representative particle size (for example, the 10% particle size D 10 ) in step S1 and the value of the void ratio n measured in step S1, the value of the side length L of the cube can be obtained from equation [5]. Once the value of L is obtained, the value of the pipe diameter d can be obtained from the value of "d / L", which is the solution of the cubic equation of equation [3].

[0021] In step S4 following step S3 in FIG. 1, based on the value of the pipe diameter d obtained in step S3 and the density ρ g of the plastic grout material, the yield stress τy of the plastic grout material is calculated. In step S4, first, the aspect of obtaining the properties required for the grout material from the size of the boulders because the grout material does not flow downward due to its own weight will be described. The rheological properties of the plastic grout material are considered to be a Bingham fluid. Figure 6 shows the relationship between the shear stress (τ) and the shear rate (γ) in a Bingham fluid. The flow formula of this Bingham fluid is as follows in Equation [6]. τ = τy + η B γ [6] Here, τ y : Yield stress η B : Plastic viscosity

[0022] Next, in Figure 7 showing the balance of the grout material in the circular pipe, consider the case where the plastic grout material in the vertically installed circular pipe 2 with diameter d is in balance due to its own weight and the frictional resistance of the inner wall surface of the circular pipe 2 and remains without flowing (flowing down). When considering the plastic grout material as a Bingham fluid, in Figure 7, it is considered that flow starts when the shear stress generated on the inner wall surface of the circular pipe 2 becomes greater than the yield stress in the Bingham fluid. And in Figure 7, from the balance condition when the grout material remains in the balanced state shown in Figure 7 without flowing downward due to its own weight in the vertically installed circular pipe 2, the following Equation [7] is obtained. (πd 2 / 4)·ρ g gL ≦ πdL·τ y [7] Here, τ y : Yield stress d: Diameter of the circular pipe L: Axial length of the plastic grout material in the circular pipe g: Acceleration due to gravity ρ g : Density of the plastic grout material

[0023] From Equation [7], the following Equation [8] is obtained. d ≦ (4τ y ) / (ρ g g) [8] From Equation [8], when considering the plastic grout material whose formulation is to be determined as a Bingham fluid, the inner diameter d of the circular pipe under the condition that the plastic grout material does not flow downward due to its own weight (Figure 7) can be obtained according to the yield stress and the density of the grout material. That is, in the circular pipe of Figure 7, the inner diameter d of the circular pipe in which the plastic grout material to be determined can continue to stay in a balanced state (the state of Figure 7) is obtained. Here, Equation [8] is an equation obtained from the balance of the plastic grout material in the circular pipe in air, and in water, it becomes the following Equation [8A]. d ≦ (4τ y ) / {(ρ g - ρ w )g} [8A] ρ w : Density of water

[0024] And, as shown in Figure 7, in the circular pipe with a diameter d, the yield stress τy of the plastic grout material that does not flow downward due to its own weight can be obtained as Equation [9] by transforming Equation [8]. τy ≧ d(ρ g g / 4) [9] Also, in water, the yield stress τy of the plastic grout material that does not move downward due to gravity can be obtained by Equation

[10] by transforming Equation [8A]. τy ≧ d{(ρ g - ρ w )g / 4}

[10]

[0025] In step S4 of Figure 1, based on the value of the inner diameter d of the circular pipe and the density ρ g of the plastic grout material in the manner described above, the yield stress τy of the plastic grout material is calculated. At that time, in the earliest stage of material selection of the plastic grout material, the density ρ g of the plastic grout material is calculated assuming the density of the standard formulation of the plastic grout material (for example, 1.8). This is because the density ρ g of the plastic grout material is often around 1.8. In step S5 of FIG. 1, the formulation of the grout material having a yield stress equal to or greater than the yield stress τy obtained in step S4 is determined. Regarding the formulation of such a grout material, it can be determined based on information regarding the formulation of the grout material in the past and its yield stress τy. In step S5, the plastic grout material of the determined formulation is manufactured, and the density ρ of the manufactured plastic grout material g is determined, and the yield stress τy is recalculated based on the determined density ρ g . Here, when determining the density in step S5, the plastic grout material may actually be manufactured, or the density of the plastic grout material may be calculated from the formulation without actually manufacturing it . Here, in order to satisfy the condition of "having a yield stress equal to or greater than the yield stress τy obtained in step S4", when determining the formulation in step S5, the yield stress τy of the plastic grout material according to the formulation A must be determined. As a method for measuring the yield stress τy used when determining the yield stress τy of such a plastic grout material, there is a method of measuring using equipment such as a rotational viscometer, a ball-pulling-up viscometer, or a parallel plate plastometer. In addition, it should be noted that there is also a method of conversion from the results of consistency tests such as a slump test and a flow test. However, in the present invention, the method for measuring the yield stress τy is not particularly limited A .

[0026] The details of step S5 will be described with reference to FIG. 8 In FIG. 8, in step S51, a formulation of a plastic grout material having a yield stress τy equal to or greater than the yield stress τy calculated in step S4 of FIG. 1 (satisfying the yield stress τy) is selected, and the plastic grout material of the formulation is manufactured. At that time, the yield stress τy of the plastic grout material of the selected formulation A is determined A . In step S52, the density ρ g in the plastic grout material of the formulation selected and manufactured in step S51 is determined. Here, in step S52 for determining the density of the plastic grout material, the density of the actually manufactured plastic grout material is actually measured to obtain the density ρ gcan be determined. Alternatively, the density ρ of the plastic grout material can be determined by calculation from the densities of the individual materials to be compounded. g can be determined. That is, when determining the density in step S52, the density of the plastic grout material actually produced in step S51 may be measured, or alternatively, without actually producing the plastic grout material in step S51, the density of the plastic grout material can also be obtained by calculation from the selected formulation. In step S53, the yield stress τy of the plastic grout material is recalculated using the density ρ determined in step S52. g 再

[0027] In step S54 in FIG. 8, the yield stress τy of the plastic grout material recalculated in step S53 is compared with the yield stress τy of the plastic grout material of the formulation selected in step S51. If the yield stress τy of the plastic grout material of the formulation selected in step S51 再 is greater than or equal to the recalculated yield stress τy A (step S54 is "Yes"), the process proceeds to step S55. A 再 On the other hand, if the recalculated yield stress τy 再 is greater than the yield stress τy of the plastic grout material of the formulation selected in step S51 A (step S54 is "No"), the process returns to step S51.

[0028] In step S55 (when τy recalculated ≤ τy A ), the yield stress τy of the plastic grout material of the formulation selected in step S51 AUpon receiving that "it is equal to or greater than the yield stress τy_recalculated in step S53", according to the formulation of the plastic grout material that satisfies the first calculated yield stress τy selected in step S51 (the yield stress τy calculated in step S4), since the plastic grout material does not flow downward but is distributed in a spherical shape, it is determined to be "appropriate", and the formulation of the plastic grout material that satisfies the yield stress τy calculated in step S4 (the formulation determined in step S51) is determined. On the other hand, when step S54 is "No" (τy_recalculated > τy A ), it returns to step S51. Based on the judgment result of step S54, the yield stress τy of the plastic grout material with the formulation selected in step S51 A is smaller than the yield stress τ y again recalculated in step S53. Therefore, it is determined that the plastic grout material with the formulation of the yield stress τy calculated in step S4 will not be distributed in a spherical shape but will flow downward when injected into the boulder ground. The formulation of the plastic grout material that satisfies the condition of "having a yield stress equal to or greater than the yield stress τy obtained in step S4" is reselected. Also in this case, the yield stress τy A recalculated for the newly selected formulation of the plastic grout material is determined. Then in step S52, the actual density of the newly selected formulation of the plastic grout material is determined, and the yield stress (τy_recalculated_recalculated) is recalculated using the density redetermined in step S53. Then, comparing the yield stress τy A recalculated for the newly selected formulation of the plastic grout material with τy_recalculated_recalculated ≤ τy A recalculated, if so, the formulation of the newly selected plastic grout material having the yield stress τy A recalculated (the formulation selected in the repeatedly performed step S51) is determined as the appropriate formulation. On the other hand, if τy_recalculated_recalculated > τy A recalculated, the routine of steps S51 to S54 is repeated. That is, the routine of steps S51 to S54 is repeated as necessary to determine the appropriate formulation of the plastic grout material.

[0029] Figures 9 and 10 show modified examples of the illustrated embodiment. The procedures of the modified example shown in FIG. 9 are different from the procedures corresponding to steps S3 and S4 in FIG. 1. The procedures corresponding to steps S1, S2, and S5 in FIG. 1 are the same as those described in FIGS. 1 to 8. In FIG. 9, for the steps different from the procedures described in FIGS. 1 to 8, they are respectively labeled as "step S3A" and "step S4A". Steps S3A and S4A will be described below. In step S3 of FIG. 1, based on the model of the boulder ground (FIG. 4), the pipe diameter d is calculated from the 10% particle size D 10 and the porosity n. In contrast, in step S3A of FIG. 9, the relationship between the size of the gravel in the model of step S2 (for example, the 10% particle size D 10 ) and the pipe diameter d (pipe diameter - gravel particle size characteristic) is specified in advance, and the pipe diameter d is determined from the specified relationship between the size of the gravel and the pipe diameter d. An example of the characteristic of the pipe diameter d and the gravel particle size is shown in FIG. 10, for example. FIG. 10 shows the relationship (characteristic) between the particle size of the boulder ground (for example, the 10% particle size D 10 ) and the pipe diameter d in the model for each porosity n (30% - 50%) of the modeled ground shown in FIGS. 4 and 5 (while changing the porosity n). The said characteristic is measured and determined for each construction site at an arbitrary timing before the implementation of the modified example of FIG. 9. In step S4A of FIG. 9, based on the value of the pipe diameter d obtained in step S3A and the density ρ of the plastic grout material g , the yield stress τy of the plastic grout material is calculated. Other configurations and effects of the modified example described with reference to FIGS. 9 and 10 are the same as those of the embodiments in FIGS. 1 to 8.

[0030] According to the illustrated embodiment, since the yield stress τy is calculated from the properties of the ground to be constructed (for example, particle size distribution and porosity n), and the formulation of the plastic grout material is determined so as to satisfy the calculated yield stress τy, the formulation can be determined based on objective criteria (parameters). In the calculation, the gravel 1 is replaced with cubes of the same size, and the model is simplified using a combination of a plurality of circular pipes 1 with the same diameter d (a network of circular pipes) to replace the gaps between the gravel. As a result of using such a model, various parameters (the length L of one side of the cube, the diameter d of the circular pipe) and the yield stress τy necessary for determining the yield stress τy can be calculated using commercially available spreadsheet software (for example, the product name "Excel" of Microsoft). Therefore, the cost related to formulation determination can be kept low. Also, based on the information (data) of the plastic grout material and its yield stress τy in the past, the formulation of the plastic grout material appropriate for each construction site can be determined.

[0031] It should be noted that the illustrated embodiment is merely an example and is not a description intended to limit the technical scope of the present invention. For example, in the illustrated embodiment, the 10% particle size D 10 is used as the size of the gravel, but the 50% particle size D 50 may also be used.

Explanation of Signs

[0032] 1 ··· Gravel 2 ··· Circular pipe d ··· Diameter of the circular pipe L ··· Length of one side of the cube (gravel) of the model

Claims

1. A step of measuring the properties of the ground to be constructed; A step of calculating the yield stress of the plastic grout material from the measured properties of the ground to be constructed; A step of determining the composition of the plastic grout material that satisfies the calculated yield stress of the plastic grout material, wherein the ground to be constructed is a gravel ground, and the properties of the gravel ground to be measured are the particle size distribution and the porosity, and the yield stress is calculated using a model in which the gravel is replaced with a cube having equal side lengths and having an annularly missing portion, and the gaps between the gravels are replaced with a combination of a plurality of circular pipes having the same diameter. A method for determining the composition of a plastic grout material, characterized by the above.

2. A step of measuring the properties of the ground to be constructed; A step of calculating the yield stress of the plastic grout material from the measured properties of the ground to be constructed; A step of determining the composition of the plastic grout material that satisfies the calculated yield stress of the plastic grout material, In the initial stage of calculating the yield stress, the density of the plastic grout material is assumed to be the density of the standard composition of the plastic grout material to be formulated, and the yield stress of the plastic grout material is calculated. Select the composition of the plastic grout material that satisfies the calculated yield stress of the plastic grout material, determine the yield stress of the selected plastic grout material, determine the actual density of the selected plastic grout material, Recalculate the yield stress using the determined actual density, Compare the recalculated yield stress with the yield stress of the selected plastic grout material. If the recalculated yield stress is less than or equal to the yield stress of the selected plastic grout material, determine the composition that satisfies the initially calculated yield stress as the composition of the plastic grout material. If the recalculated yield stress is greater than the yield stress of the selected plastic grout material, re-determine the composition of the plastic grout material that satisfies the initially calculated yield stress, determine the yield stress of the plastic grout material whose composition has been re-determined, determine the actual density of the plastic grout material whose composition has been re-determined, recalculate the yield stress of the plastic grout material whose composition has been re-determined using the determined actual density, and compare the recalculated yield stress with the yield stress of the plastic grout material whose composition has been re-determined. A method for determining the composition of a plastic grout material, characterized by the above.

3. A step of measuring the properties of the ground to be constructed; A step of calculating the yield stress of the plastic grout material from the measured properties of the ground to be constructed; A step of determining a composition of a plastic grout material having a yield stress equal to or higher than the calculated yield stress of the plastic grout material is included. The ground to be constructed is a gravel ground, and the properties of the measured gravel ground are particle size distribution and porosity. The yield stress is calculated using a model in which gravel is replaced with a cube having sides of equal length and having an annularly missing portion, and the gaps between the gravel are replaced with a combination of a plurality of circular pipes of the same diameter. A method for determining the composition of a plastic grout material, characterized in that the length of one side of the cube of the model is the 50% particle size representing the average size of the boulders.

4. A step of measuring the properties of the ground to be constructed, A step of calculating the yield stress of the plastic grout material from the measured properties of the ground to be constructed, A step of determining a composition of a plastic grout material having a yield stress equal to or higher than the calculated yield stress of the plastic grout material is included. The ground to be constructed is a gravel ground, and the properties of the measured gravel ground are particle size distribution and porosity. The yield stress is calculated using a model in which gravel is replaced with a cube having sides of equal length and having an annularly missing portion, and the gaps between the gravel are replaced with a combination of a plurality of circular pipes of the same diameter. A method for determining the composition of a plastic grout material, characterized in that the length of one side of the cube of the model is the 10% particle size.

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