Mixing device, and mixing method

Abstract

To provide a mixing device capable of spraying solidification material at high pressure and low pressure, and a mixing method constructing foundation structure of an existing building using such a mixing device.SOLUTION: A mixing device (100) has a main body (10) provided with a mixing blade (1), a co-rotation prevention member (2), and a mixing and high-pressure solidification material injection blade (3). The mixing and high-pressure solidification material injection blade is located closest to the ground, a high-pressure solidification material injection device (4) is provided at a radially outer end. A low-pressure solidification material injection device (5) is provided near an underground side tip of the main body. In a chamber (15) communicating with the mixing and high-pressure solidification material injection blade, a high-pressure solidification material supply flow path (12) turns radially outward and branches into two radial flow paths (12A). A piping constituting a low-pressure solidification material supply flow path (11) branches into multiple pipes which are arranged in two circumferential regions where the two radial flow paths do not extend and join in a region closer to a ground side than the radial flow paths.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an improvement in an agitation device used in a mechanical agitation method, and to an agitation method using the improved agitation device. [Background technology]

[0002] The mixing method, a type of ground improvement method carried out when the ground at a construction site is weak, uses a mixing device equipped with rotating mixing blades to mix and mix the ground-forming soil with a solidification material (improvement material) to create an underground solidified body. In this regard, a technique has been proposed in which a solidifying material is sprayed at high speed while rotating an agitating blade (for example, Patent Documents 1, 2, and 3).

[0003] In such conventional techniques (Patent Documents 1 to 3), the solidification material is sprayed at high pressure from the radial tip of the stirring blade. However, there has been no proposal in the prior art for an impeller that can inject a high-pressure solidification material from the radial tip of the impeller and simultaneously inject a low-pressure solidification material from the underground tip of the impeller. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 63-29050 [Patent Document 2] JP 2004-225361 A [Patent Document 3] Special Publication No. 6-37767 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide a mixing device that can simultaneously spray high-pressure solidification material and low-pressure solidification material, and to provide a mixing method using such a mixing device to construct the foundation structure of an existing building. [Means for solving the problem]

[0006] The stirring device (100) of the present invention is The main body (10) is provided with an agitating blade (1), a member for preventing co-rotation (2), and an agitating and high-pressure solidification material injection blade (3), The impeller (3) for stirring and high-pressure solidification material injection is located at the lowest position (underground side), and a high-pressure solidification material injection device (4) is provided at its radially outer end. A low-pressure solidification material injection device (5) is provided near the lower end (ground end) of the main body (10) and at a position offset radially outward from the central axis. A low-pressure solidification material supply flow path (11) for supplying a solidification material to the low-pressure solidification material injection device (5), and a high-pressure solidification material supply flow path (12) for supplying a solidification material to the high-pressure solidification material injection device (4) are provided. The rod (14) connecting the (upper or ground side) universal joint (13: swivel joint) and the agitating blade (1) is composed of a double pipe, the outer pipe of the double pipe (14) constitutes the low-pressure solidification material supply passage (11), and the inner pipe of the double pipe (14) constitutes the high-pressure solidification material supply passage (12), A chamber (15) communicating with the impeller (3) for stirring and injecting high-pressure solidification material is formed inside the main body (10), and in the chamber (15), the high-pressure solidification material supply passage (12) turns radially outward and branches into two radial passages (12A) extending radially outward, and the two radial passages (12A) extend in the diametrical direction of the main body (10); The outer pipe of the double pipe (14A) constituting the low-pressure solidification material supply passage (11) branches into a plurality of pipes (e.g., 12 pipes: branched low-pressure solidification material supply passage 11A) extending in the axial direction of the double pipe, and half of the plurality of pipes (branched low-pressure solidification material supply passage 11A) (e.g., six branched low-pressure solidification material supply passages 11A) and the remaining half of the pipes (e.g., the remaining six branched low-pressure solidification material supply passages 11A) are respectively arranged in two circumferential regions (R1, R2) of the main body (10) where the two radial passages (12A: high-pressure solidification material supply passages) do not extend, and Half of the pipes (e.g., six branched low-pressure solidification material supply passages 11A) and the remaining half of the pipes (e.g., the remaining six branched low-pressure solidification material supply passages 11A) arranged in the circumferential regions (R1, R2) are arranged linearly symmetrically with respect to the two radial passages (12A) extending in the diameter direction of the main body (10), and the half of the pipes (e.g., the six branched low-pressure solidification material supply passages 11A) and the remaining half of the pipes (e.g., the remaining six branched low-pressure solidification material supply passages 11A) merge in a region within the main body (10) below (underground side) the two radial passages (12A). In this specification, the double-tube rod of the agitator (100) is designated by the reference numeral "14" and the double-tube rod in the main body (10) is designated by the reference numeral "14A", but both constitute the same double-tube rod.

[0007] In the present invention, a hollow portion (16) and a sleeve-shaped member (17) that is placed (fitted) into the hollow portion (16) are provided at the point inside the main body (10) where the high-pressure solidification material supply passage (12) changes direction radially outward, and it is preferable that the sleeve-shaped member (17) is heat-treated and configured to be replaceable. In addition, in the present invention, it is preferable that half of the pipes (e.g., six branched low-pressure solidification material supply passages 11A) and / or the remaining half of the pipes (e.g., the remaining six branched low-pressure solidification material supply passages 11A) arranged in the two circumferential regions are arranged at equal intervals in the circumferential direction in each of the two circumferential regions. Furthermore, in the present invention, it is preferable that the two radial flow paths (12A: high-pressure solidification material supply flow paths) have an inner diameter of 22 mm or more.

[0008] The stirring method of the present invention is a stirring method using the stirring device (100: the stirring device according to any one of claims 1 to 4), A drilling step of drilling a borehole (H) from the ground surface to a stable layer (e.g., bedrock) by the stirring device (100) near an existing structure (ES: including an underground foundation portion of the existing structure); The method includes the steps of: while pulling up the stirring device (100) from the bottom of the borehole (H) drilled in the hole drilling step, injecting a solidification material from a low-pressure solidification material injection device (5) near the lower end (underground tip) of the main body (10), and injecting the solidification material from a high-pressure solidification material injection device (4) provided at the radially outer end of the stirring and high-pressure solidification material injection blade (3) so that the solidification material reaches the existing structure (ES), thereby creating an underground solidified body (20) in contact with the existing structure (ES). Effect of the Invention

[0009] According to the present invention having the above-mentioned configuration, a chamber (15) communicating with the impeller (3) for stirring and high-pressure solidification material injection is formed inside the main body (10), and in the chamber (15), the high-pressure solidification material supply passage (12) turns radially outward and branches into two radial passages (12A) extending radially outward, and the two radial passages (12A) extend in the diameter direction of the main body (10), constituting the low-pressure solidification material supply passage (11). The outer pipe of the double pipe (14A) is branched into a plurality of pipes (for example, 12 pipes: branched low-pressure solidification material supply passages 11A) extending in the axial direction of the double pipe, and half of the plurality of pipes (6 branched low-pressure solidification material supply passages 11A) and the remaining half of the pipes (the remaining 6 branched low-pressure solidification material supply passages 11A) are in the circumferential region of the main body (10) and are in two circumferential directions where the two radial directions (12A: high-pressure solidification material supply passages) do not extend. The pipes (six branched low-pressure solidification material supply passages 11A) and the remaining half of the pipes (the remaining six branched low-pressure solidification material supply passages 11A) arranged in the two circumferential regions (R1, R2) are arranged symmetrically with respect to the two radial flow passages (12A) extending in the diameter direction of the main body (10). The pipes and the remaining half of the pipes join in a region inside the main body (10) below (underground side) the two radial flow passages (12A). Therefore, the high-pressure (e.g., 20 MPa to 50 MPa) solidification material supplied through the inner pipe of the double pipe (14, 14A) and the low-pressure (e.g., 5 MPa or less) solidification material supplied through the outer pipe of the double pipe (14, 14A) are sprayed from the same stirring device (100) without being mixed at a stage before being sprayed from the stirring blade (3: stirring and high-pressure solidification material spraying blade) or the main body (10). Therefore, the surrounding soil can be cut with a high-pressure solidification material to increase the cross-sectional area of ​​the underground solidification body (20) to be created, while a large amount of low-pressure solidification material can be supplied to mix the soil at the construction site with the solidification material, thereby creating the underground solidification body (20). In addition, the low-pressure solidification material supplied through the outer pipe of the double pipe (14, 14A) can be sprayed from the tip on the underground side, so that the hardening material can be mixed into the ground, reducing the resistance to drilling. Here, since the low-pressure solidification material supply flow path (11) to which the low-pressure solidification material is supplied is branched into the multiple pipes (11A) and merges, the pressure loss when branching into the multiple pipes (11A) and the pressure loss when the multiple pipes merge are relatively small, which saves the required pressurization energy.

[0010] Here, at the point where the high pressure solidification material supply passage (12) turns radially outward, the pressure is high, and the wear at the point of turn is large. However, in the present invention, a hollow portion (16) and a sleeve-shaped member (17) arranged (fitted) in the hollow portion (16) are provided at the location inside the main body (10) where the high-pressure solidification material supply passage (12) turns radially outward, and if the sleeve-shaped member (17) is heat-treated, the direction of the high-pressure solidification material is turned inside the sleeve-shaped member (17), so that the amount of wear of the sleeve-shaped member (17) can be reduced by heat-treating the sleeve-shaped member (17). Furthermore, in the present invention, if the sleeve-shaped member (17) is configured to be replaceable, it can be immediately replaced even if it wears out, and the life of the entire agitator (100) can be extended.

[0011] Furthermore, in the present invention, by setting the inner diameter of the two radial flow paths (12A: high-pressure solidification material supply flow paths) to 22 mm or more, the flow path resistance when the high-pressure (20 MPa to 50 MPa) solidification material flows through the two radial flow paths (12A) is reduced, and the high-pressure solidification material changes from a turbulent state to a laminar flow or a state close to laminar flow. As a result, the amount of wear of the two radial flow paths (12A) is reduced.

[0012] According to the mixing method of the present invention, since the mixing device (100: the mixing device of any one of claims 1 to 4) is used, a high pressure (e.g., 20 MPa to 50 MPa) solidification material and a low pressure (e.g., 5 MPa or less) solidification material can be sprayed from the same mixing device (100) without being mixed before being sprayed from the mixing blade (3: blade for mixing and spraying high pressure solidification material) or the main body (10). The method includes the steps of injecting the solidification material from the low-pressure solidification material injection device (5) near the lower end (ground tip) of the main body (10) while pulling up the agitation device (100) from the bottom of the borehole (H), and injecting the solidification material from the high-pressure solidification material injection device (4) provided at the radially outer end of the agitation and high-pressure solidification material injection blade (3) so as to reach the existing structure (ES), thereby creating an underground solidification body (20) in contact with the existing structure (ES), so that the jet of the solidification material can be reliably caused to collide with the existing structure (ES) to create an underground solidification body (20) in contact with the existing structure (ES). Therefore, the existing structure (ES) is reliably improved in earthquake resistance and bearing capacity against soft ground by the underground solidification body (20).

[0013] Furthermore, in the stirring device (100), the stirring and high-pressure solidification material injection blade (3) with the high-pressure solidification material injection device (4) at its radially outer end is located at the lowest (underground side). Therefore, when the excavation process is completed, the stirring and high-pressure solidification material injection blade (3) is in contact with or very close to the stable layer (e.g., bedrock) to which the drilling hole (H) reaches. Therefore, when the stirring device (100) is pulled up to create the underground solidified body (20), the high-pressure solidification material is injected at a position in contact with or very close to the stable layer, and the radial dimension of the bottom layer of the created underground solidified body (20) is equal to the radial dimension of the area above it. The radial dimension of the bottom layer of the underground solidified body (20) is smaller than the radial dimension of the area above it, and the bottom region of the underground solidified body (20) is prevented from being strangled. [Brief description of the drawings]

[0014] [Figure 1] 1 is an explanatory cross-sectional view showing a stirring device according to an embodiment of the present invention. [Diagram 2] 2 is an explanatory cross-sectional view showing details of a portion of the main body in FIG. 1 where blades for stirring and high-pressure solidification material injection are provided. FIG. [Diagram 3] FIG. 3 is an explanatory cross-sectional view taken along the line A3-A3 of FIG. 2. [Figure 4]FIG. 3 is a partially enlarged cross-sectional explanatory view of a portion in FIG. 2 where the high-pressure solidification material supply flow passage changes direction radially outward inside the main body. [Diagram 5] FIG. 5 is a process diagram of an agitation method using the agitation device shown in FIGS. 1 to 4, and is an explanatory diagram showing a process of drilling holes in the vicinity of an existing building. [Figure 6] FIG. 6 is an explanatory view showing a step following FIG. 5, in which the stirring device is lifted up to form an underground solidified body. [Figure 7] 7 is an explanatory plan view showing the relative positional relationship between the underground solidified body and the existing structure after the process shown in Figures 5 and 6. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In Fig. 1, the entire agitation device according to the embodiment of the present invention is indicated by the reference numeral 100. The agitation device 100 has a main body 10 (agitator main body), and two agitation blades 1, a member 2 for preventing co-rotation, and a blade 3 for agitation and high-pressure solidification material injection are provided on the main body 10. In other words, the portion below the agitation blades 1 in Fig. 1 is the main body 10. The mixing and high-pressure solidification material injection blade 3 is located at the lowest position (underground side) in Fig. 1. A high-pressure solidification material injection device 4 is provided at the radially outer end of the mixing and high-pressure solidification material injection blade 3. A plurality of hole-boring bits 6 are arranged along the entire longitudinal direction at the lower part (underground side) of the mixing and high-pressure solidification material injection blade 3. A member 2 for preventing co-rotation is disposed above (on the ground side) the impeller 3 for stirring and injecting high-pressure solidification material, and two stirring blades 1 are disposed further above (on the ground side) the member 2 for preventing co-rotation. In the stirring device 100, the stirring blade 1, the member 2 for preventing co-rotation, the impeller 3 for stirring and injecting high-pressure solidification material, the double-tube rod 14A extending between the low-pressure solidification material injector 5 described later, the rod 14B (single tube), and the mounting members may be collectively referred to as the "main body 10." The double-tube rod of the agitator 100 is indicated by the reference symbol "14" and the double-tube rod in the main body 10 is indicated by the reference symbol "14A", but both constitute the same double-tube rod. The mixing and high-pressure solidification material injection blade 3 and the mixing blade 1 are attached to the double-tube rod 14A and rotate together with the double-tube rod 14A. The co-rotation prevention member 2 has the function of preventing the soil mixed by the mixing blade 1 and the mixing and high-pressure solidification material injection blade 3 from "rotating together" with the rotation of the mixing blade 1 and the mixing and high-pressure solidification material injection blade 3. Therefore, the co-rotation prevention member 2 does not rotate in the same way as the double-tube rod 14A, the mixing blade 1, and the mixing and high-pressure solidification material injection blade 3.

[0016] A low-pressure solidification material injection device 5 is provided at a position (position radially outwardly offset from the central axis) near the lower end (ground side tip) of the main body 10. Here, the lower end of the main body 10 is formed into a truncated cone with a smaller diameter the closer it is to the lower end (ground side), and the low-pressure solidification material injection device 5 is disposed on the side of the truncated cone, near the tip of the truncated cone (near the ground side tip). In the illustrated embodiment, one low-pressure solidification material injection device 5 is arranged on the side of the truncated cone, but depending on the construction conditions and other factors, two or more low-pressure solidification material injection devices 5 can also be arranged.

[0017] In the mixing device 100 of Fig. 1, the main body 10 and the area above ground from the main body 10 are provided with a low-pressure solidification material supply passage 11 that supplies solidification material to the low-pressure solidification material jetting device 5, and a high-pressure solidification material supply passage 12 that supplies solidification material to the high-pressure solidification material jetting device 4. In Fig. 1 (and Figs. 2 to 4), the high-pressure solidification material supply passage 12 and the low-pressure solidification material supply passage 11, including the solidification material jetted from the high-pressure solidification material jetting device 4 or the low-pressure solidification material jetting device 5, are each indicated by a different type of hatching. The high-pressure solidification material supply passage 12 and the low-pressure solidification material supply passage 11 are connected on the ground side to a high-pressure solidification material supply source (including a high-pressure pump) and a low-pressure solidification material supply source (including a low-pressure pump), not shown, respectively, and the high-pressure solidification material and the low-pressure solidification material are supplied to the mixing device 100 by driving the high-pressure and low-pressure pumps. A universal joint 13 (swivel joint) is provided near the ground side end of the mixer 100, and the mixer 100 is connected via the swivel joint 13 to a high pressure solidification material supply source or a low pressure solidification material supply source (not shown).

[0018] The swivel joint 13 and the stirring blades 1, 1 are attached to the double-tube rod 14. As described above, the double-tube rod 14 constitutes the same double tube as the double-tube rod 14A (the double-tube rod 14A in the main body 10) in the region between the stirring blades 1, 1 and the stirring and high-pressure solidification material injection blade 3. The outer tubes of the double-tube rods 14 and 14A constitute a part of the low-pressure solidification material supply passage 11, and the inner tubes of the double-tube rods 14 and 14A constitute a part of the high-pressure solidification material supply passage 12.

[0019] As shown in Figures 1 and 2, the high-pressure solidification material supply passage 12 turns radially outward in a chamber 15 (not shown in Figure 1: see Figures 2 and 4), and branches into two radial passages 12A extending radially outward. Here, the chamber 15 is provided inside the main body 10, and is connected to the stirring and high-pressure solidification material injection blades 3. Each of the two radial passages 12A is constructed of piping. The configuration in which the high-pressure solidification material supply passage 12 branches into the two radial passages 12A will be described later with reference to Figure 4, etc. The two radial flow paths 12A are arranged within the stirring and high-pressure solidification material injection blade 3, extend radially outward (in the direction of the diameter extension) of the main body 10, and are connected to the high-pressure solidification material injection device 4 (Figure 1) at their radial ends (diameter ends). Here, the inner diameter of the two radial flow passages 12A is set to 22 mm or more. Since the inner diameter is set to a relatively large dimension of 22 mm or more, the flow resistance when the high-pressure (20 MPa to 50 MPa) solidification material flows through the two radial flow passages 12A is reduced, and the high-pressure solidification material changes from a turbulent state to a laminar flow or a state close to laminar flow. As a result, the amount of wear of the two radial flow passages 12A can be reduced.

[0020] 2, which shows a detailed cross section of the area where the stirring and high-pressure solidification material injection blades 3 are provided, a housing 18 constituting a part of the main body 10 is provided outside the low-pressure solidification material supply passage 11 and the high-pressure solidification material supply passage 12, and the stirring and high-pressure solidification material injection blades 3 are attached to the housing 18. The two radial passages 12A pass through the housing 18 and communicate with a chamber 15 (see FIG. 4) in a sleeve-shaped member 17 (see FIG. 4). In Figures 1 and 2, the high-pressure solidification material flows from a high-pressure solidification material supply source (not shown) on the ground side through a swivel joint 13, through a high-pressure solidification material supply passage 12 consisting of the inner tubes of double-tube rods 14, 14A, through a radial passage 12A within a stirring and high-pressure solidification material injection blade 3, and is injected into the ground from a high-pressure solidification material injection device 4 (arrow J2: Figure 1).

[0021] In Fig. 1, the low-pressure solidification material supply passage 11 communicates with or is connected to the low-pressure solidification material injection device 5 in a region below (underground side) the branching point (where the stirring and high-pressure solidification material injection blades 3 are located) where the high-pressure solidification material supply passage 12 branches into two radial flow passages 12A. The low-pressure solidification material supply passage 11 is configured so as not to interfere with the two radial flow passages 12A when passing through the branching point where the high-pressure solidification material supply passage 12 branches into two radial flow passages 12A. This configuration is shown in Figs. 2 and 3. 2 and 3, the outer tube of the double-tube rod 14A constituting the low-pressure solidification material supply passage 11 branches into multiple pipes (12 pipes in the illustrated embodiment) in an area on the ground side (upper in FIG. 2) from the point where the high-pressure solidification material supply passage 12 branches into two radial passages 12A, and the multiple branched pipes extend in the axial direction of the double-tube rod 14A. Each of the 12 branched pipes constitutes a branched low-pressure solidification material supply passage 11A. As shown in Figure 3, the circumferential positions of half of the 12 pipes (six branched low-pressure solidification material supply passages 11A) and the remaining half of the pipes (the remaining six branched low-pressure solidification material supply passages 11A) are respectively arranged in two circumferential regions R1 and R2 which are circumferential regions of the main body 10 and into which the two radial passages 12A (high-pressure solidification material supply passages) do not extend. The six pipes (six branched low-pressure solidification material supply passages 11A) and the remaining six pipes (the remaining six branched low-pressure solidification material supply passages 11A) arranged in the two circumferential regions R1 and R2 are arranged so as to be linearly symmetrical with respect to the two radial passages 12A (high-pressure solidification material supply passages) extending in the diameter direction of the main body 10. Furthermore, the six branched low-pressure solidification material supply passages 11A (pipes) and the remaining six branched low-pressure solidification material supply passages 11A (pipes) arranged in the two circumferential regions R1 and R2 are arranged at equal intervals in the circumferential direction in each of the circumferential regions R1 and R1.

[0022] In Fig. 2, the 12 branched low-pressure solidification material supply passages 11A (6 branched low-pressure solidification material supply passages 11A and the remaining 6 branched low-pressure solidification material supply passages 11A) branched from the low-pressure solidification material supply passage 11 in the above-mentioned manner join in an area inside the main body below (underground side) the two radial passages 12A (high-pressure solidification material supply passages) to form a joined low-pressure solidification material supply passage 11B. In Figs. 1 and 2, the rod in the portion where the joined low-pressure solidification material supply passage 11B extends is indicated by the symbol 14B. Note that since only the low-pressure solidification material flows through the rod 14B, it does not need to be a double pipe and is composed of a single pipe. The joined low-pressure solidification material supply passage 11B communicates (is connected to) with a low-pressure solidification material injection device 5 (FIG. 1) disposed near the lower end (ground side tip) of the main body 10. In Figures 1 and 2, the low-pressure solidification material flows from a low-pressure solidification material supply source (not shown) on the ground side through a swivel joint 13, passes through a low-pressure solidification material supply flow path 11 consisting of a double tube rod 14 and an outer tube 14A, 12 branched low-pressure solidification material supply flow paths 11A (Figure 2), and a merged low-pressure solidification material supply flow path 11B (Figure 2), and is injected into the ground from a low-pressure solidification material injection device 5 (arrow J1: Figure 1).

[0023] As shown in Figures 1 to 3, the high pressure (e.g., 20 MPa to 50 MPa) solidification material supplied through the inner tube of the double tube rod 14, 14A and the low pressure (e.g., 5 MPa or less) solidification material supplied through the outer tube of the double tube rod 14, 14A, rod 14B are sprayed from the same stirring device 100 without being mixed (the high pressure and low pressure solidification materials) before being sprayed from the high pressure solidification material spraying device 4 of the stirring and high pressure solidification material spraying blade 3 or the low pressure solidification material spraying device 5 at the lower end of the main body 10. Therefore, by injecting high-pressure solidification material (J2: see Figure 1) to cut the surrounding soil and increase the cross-sectional area of ​​the underground solidification body to be created, and by injecting a large amount of low-pressure solidification material (J1: see Figure 1) to mix the soil at the construction site with a large amount of solidification material, it is possible to create a high-quality underground solidification body. Here, the low-pressure solidification material supply flow path 11, which branches into multiple (12) low-pressure solidification material supply flow paths 11A and merges into a single low-pressure solidification material supply flow path 11B below (underground side) the radial flow path 12A, is a low-pressure solidification material supply flow path 11 to which low-pressure solidification material is supplied. Since the pressure of the low-pressure solidification material flowing through the low-pressure solidification material supply flow path 11 is relatively small (for example, 5 MPa or less), the pressure loss when branching into the 12 pipes 11A and the pressure loss when the 12 pipes 11A merge are relatively small, and the required pressurization energy is saved accordingly.

[0024] With reference to Fig. 4, a configuration will be described in which the high-pressure solidification material supply passage 12 turns radially outward inside the main body 10. In Fig. 4, the point where the high-pressure solidification material supply passage 12 turns radially outward is near the lower end of the high-pressure solidification material supply passage 12, and is approximately the center in the width direction (vertical direction in Fig. 4) of the stirring and high-pressure solidification material injection blade 3 (not shown in Fig. 4). In Fig. 4, at the point where the direction is changed, there is provided a hollow portion 16 inside the main body 10, and a sleeve-shaped member 17 disposed in the hollow portion 16. In Fig. 4, the hatching applied to the sleeve-shaped member 17 is of a different type from the hatching of the solidifying material flow paths 12, 11. The internal space of the sleeve-shaped member 17 constitutes a chamber 15. The chamber 15 communicates with the high-pressure solidification material supply flow passage 12 via an upper connection portion 17A at the top of the sleeve-shaped member 17, and communicates with each of the two radial flow passages 12A via two side connection portions 17B provided on the side of the sleeve-shaped member 17. The sleeve-shaped member 17 is fixed to a mounting member 19 in the cavity portion 16 of the main body 10.

[0025] Here, the sleeve-shaped member 17 has been heat-treated, and is configured to be replaceable (i.e., detachable from the mounting member 19). Because the sleeve-shaped member 17 has been heat-treated, it is possible to reduce the amount of wear in the sleeve-shaped member 17 when the high-pressure solidification material changes direction inside the sleeve-shaped member 17. Furthermore, because the sleeve-shaped member 17 is configured to be replaceable, even if the sleeve-shaped member 17 becomes worn, it is possible to immediately replace it, thereby extending the life of the entire mixing device 100. In Fig. 4, the high-pressure solidification material introduced into the chamber 15 from the high-pressure solidification material supply passage 12 through the upper connection part 17A of the sleeve-shaped member 17 changes direction in two radially outward directions (left and right directions in Fig. 4) within the chamber 5, flows into the radial passages 12A through the two side connection parts 17B of the sleeve-shaped member 17, and passes through the radial passages 12A. Then, as shown in Fig. 1, the high-pressure solidification material is sprayed into the ground as a jet J2 from the high-pressure solidification material spraying device 4.

[0026] Next, the mixing method of the illustrated embodiment will be described with reference to Figs. Fig. 5 shows the drilling process, in which the mixing device 100 is installed near the existing structure ES (including its underground foundation). When installing the mixing device 100, the installation position of the mixing device 100 is set so that the solidification material injected from the high-pressure solidification material injection device 4 in the process of Fig. 6 reaches the existing structure ES. To avoid complication in the illustration, Fig. 5 shows two mixing blades 1 provided on the main body 10 of the mixing device 100, a mixing and high-pressure solidification material injection blade 3, a high-pressure solidification material injection device 4 at the radially outer end of the mixing and high-pressure solidification material injection blade 3, and a low-pressure solidification material injection device 5 near the lower end (ground side tip) of the main body 10. The member 2 for preventing co-rotation (see Fig. 1) is not shown in Fig. 5 and Fig. 6 described later. Then, the rods 14 (double-tube rods 14, 14A, and single-tube rod 14B) are rotated by a driving device (not shown) and penetrated into the ground, drilling a borehole H that reaches a stable layer (e.g., bedrock BR) from the ground surface. Such drilling is made possible by a plurality of drilling bits 6 (see FIG. 1) arranged on the mixing and high-pressure solidification material injection blades 3.

[0027] Next, the process shown in Fig. 6 is carried out. Fig. 6 shows the process of creating an underground solidified body 20, in which the stirring device 100 is pulled up from the bottom of the borehole H drilled in the hole drilling process of Fig. 5 as shown by the arrow U while rotating the rod 14. At the same time as the mixing device 100 is pulled up, low-pressure solidification material is sprayed from the low-pressure solidification material spraying device 5 near the lower end (ground tip) of the main body 10 (arrow J1), and at the same time, high-pressure solidification material is sprayed from the high-pressure solidification material spraying device 4 provided at the radially outer end of the mixing and high-pressure solidification material spraying blade 3 so that it reaches the underground foundation portion ES of the existing building (arrow J2). By ensuring that the high-pressure solidification material jet J2 hits the underground foundation portion ES of the existing structure, it is possible to create an underground solidified body 20 that is in contact with the underground foundation portion ES of the existing structure. This ensures that the earthquake resistance or bearing capacity of the existing structure ES against soft ground is improved by the underground solidified body 20. The radial dimension of the bottom layer of the created underground solidified body 20 is indicated by the symbol L.

[0028] The positional relationship between the underground solidified body 20 constructed by the steps of FIGS. 5 and 6 and the existing building (its underground foundation portion) ES is shown in a plan view in FIG. In FIG. 7, the solidification material injection region RJ2 from the high-pressure solidification material injection device 4 reaches the existing building (its underground foundation portion) ES. Here, the trajectory of the two stirring blades 1 and the member 2 for preventing co-rotation is the same as the trajectory 3M of the blade 3 for stirring and high-pressure solidification material injection, and the respective operating trajectories of the two stirring blades 1, the member 2 for preventing co-rotation, and the blade 3 for stirring and high-pressure solidification material injection do not overlap with the underground foundation part ES of the existing building. This means that the two stirring blades 1, the member 2 for preventing co-rotation, and the blade 3 for stirring and high-pressure solidification material injection are prevented from interfering with the underground foundation part ES of the existing building. In other words, in Figure 6, the underground solidified body 20 is in contact with the existing building (its underground foundation part) ES, but this is because only the solidification material injection area RJ2 from the high-pressure solidification material injection device 4 has reached the existing building (its underground foundation part) ES; the tips of the two agitating blades 1, the tip of the anti-rotation member 2, and the tip of the agitating and high-pressure solidification material injection blade 3 have not reached the existing building (its underground foundation part) ES.

[0029] In the illustrated embodiment of the stirring device 100, the stirring and high-pressure solidification material injection blade 3, which is provided with the high-pressure solidification material injection device 4 at its radially outer end, is located at the lowest part (underground side) of the stirring device 100 (FIGS. 1, 5, 6). Therefore, when the excavation process is completed, the stirring and high-pressure solidification material injection blade 3 is in contact with or very close to the stable layer BR (e.g., bedrock) that the borehole H reaches. Therefore, when the mixing device 100 is pulled up to create the underground solidified body 20, high-pressure solidification material is sprayed from a position that is in contact with or very close to the stable layer BR, so that the radial dimension of the bottom layer of the created underground solidified body 20 (radial dimension L in Figure 6) will not be smaller than the radial dimension of the underground solidified body 20 above it, and the bottommost region of the underground solidified body 20 will not be strangled. It should be noted that the illustrated embodiment is merely an example and is not intended to limit the technical scope of the present invention. [Explanation of symbols]

[0030] 1... Stirring blade 2. Anti-rotation parts 3. Impeller for mixing and high pressure solidification material injection 4. High pressure solidification material injection device 5. Low pressure solidification material injection device 10. Main unit 11. Low pressure solidification material supply channel 11A: Low pressure solidification material supply flow path after branching 11B: Low pressure solidification material supply flow path after junction 12 High pressure solidification material supply channel 12A Radial flow path (high pressure solidification material supply flow path) 13 Swivel joint 14 Rod (double tube rod, etc.) 15. Chamber 16...Cavity part 17 Sleeve-shaped member 20...Ground consolidation 100... Stirring device ES: Underground foundations of existing buildings H...Drilling hole

Claims

1. The main body is provided with an agitating blade, a member for preventing co-rotation, and a blade for agitation and high-pressure solidification material injection. The stirring and high-pressure solidification material injection blade is located at the lowest position, and a high-pressure solidification material injection device is provided at the radially outer end thereof, A low-pressure solidification material injection device is provided near the lower end of the main body and at a position offset radially outward from the central axis, A low-pressure solidification material supply flow path is provided for supplying a solidification material to the low-pressure solidification material injection device, and a high-pressure solidification material supply flow path is provided for supplying a solidification material to the high-pressure solidification material injection device, The rod connecting the universal joint and the stirring blade is made of a double pipe, the outer pipe of the double pipe constitutes the low-pressure solidification material supply passage, and the inner pipe of the double pipe constitutes the high-pressure solidification material supply passage, A chamber is formed inside the main body, the chamber being in communication with impellers for stirring and injecting high-pressure solidification material, and in the chamber, the high-pressure solidification material supply passage turns radially outward and branches into two radial passages extending radially outward, the two radial passages extending in the diametrical direction of the main body, A mixing device characterized in that the outer pipe of the double pipe that constitutes the low-pressure solidification material supply flow path branches into a plurality of pipes extending in the axial direction of the double pipe, half of the plurality of pipes and the remaining half of the pipes are respectively arranged in two circumferential regions of the main body where the two radial flow paths do not extend, half of the pipes and the remaining half of the pipes arranged in the two circumferential regions are arranged linearly symmetrically with respect to the two radial flow paths extending in the diameter direction of the main body, and the half of the pipes and the remaining half of the pipes join in a region within the main body below (underground) the two radial flow paths.

2. The stirring device of claim 1, wherein a hollow portion is provided at a point inside the main body where the high-pressure solidification material supply flow path changes direction radially outward, and a sleeve-shaped member is placed in the hollow portion, the sleeve-shaped member being heat-treated and configured to be replaceable.

3. 2. The mixing device according to claim 1, wherein half of the pipes and / or the remaining half of the pipes arranged in the two circumferential regions are arranged at equal intervals in the circumferential direction in each of the two circumferential regions.

4. 2. The stirring device of claim 1, wherein the two radial flow passages have an inner diameter of 22 mm or more.

5. A stirring method using the stirring device according to any one of claims 1 to 4, A drilling step of drilling a borehole from the ground surface to a stable layer by the stirring device near an existing structure; A mixing method characterized by including a step of: pulling up a mixing device from the bottom of the excavation hole drilled in the hole drilling step, injecting solidification material from a low-pressure solidification material injection device near the lower end of the main body, and injecting solidification material from a high-pressure solidification material injection device provided at the radially outer end of the mixing and high-pressure solidification material injection blade so that it reaches the existing structure, thereby creating an underground solidified body in contact with the existing structure.

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