Columnar improved body with core material

Abstract

To reduce positional deviation of rod-like steel materials against a columnar improvement body.SOLUTION: A columnar improvement body 10 with a core material comprises a columnar improvement body 10 provided in the ground G and a core material 12 embedded in the columnar improvement body 10. The core material 12 includes: a first wall-shaped bar 20 having a plurality of bar-shaped steel members 22 and a wavy shear reinforcing bar 24 connecting the plurality of bar-shaped steel members 22; a second wall-shaped bar 20 having a plurality of bar-shaped steel members 22 and a wavy shear reinforcing bar 24 connecting the plurality of bar-shaped steel members 22 and facing the first wall-shaped bar 20; and a connecting steel bar 26 connecting a lower part of the bar-shaped steel member 22 of the first wall-shaped bar 20 to a lower part of the bar-shaped steel member 22 of the second wall-shaped bar 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a columnar improvement body with a core material.

Background Art

[0002] There is known a landslide prevention method in which a core material is embedded in a columnar improvement body (soil-cement column body) (see, for example, Patent Documents 1 and 2). Also, in a reinforced concrete member, shear reinforcing bars arranged obliquely with respect to main reinforcing bars are known (see, for example, Patent Documents 3 and 4).

[0003] In the technique disclosed in Patent Document 2, while vibrating an H-shaped steel to which a reinforcing bar cage as a core material is attached, after dropping it into a columnar improvement body before curing, only the H-shaped steel is pulled up to embed the reinforcing bar cage inside the columnar improvement body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technique disclosed in Patent Document 2, if a bar-shaped steel material such as a reinforcing bar constituting a reinforcing bar cage is displaced with respect to the columnar improvement body, the shear strength of the columnar improvement body may decrease.

[0006] In consideration of the above facts, an object of the present invention is to reduce the displacement of the bar-shaped steel material with respect to the columnar improvement body. [Means for solving the problem]

[0007] The construction method for a columnar improved body with a core material according to the first embodiment comprises a dropping step in which a wall-like reinforcement, in which a plurality of rod-shaped steel members connected by shear reinforcement bars is arranged on both sides of the web, and an H-shaped steel to which the upper part of the rod-shaped steel members is attached is dropped into the columnar improved body before hardening while being vibrated, and a lifting step in which the upper part of the rod-shaped steel members is removed from the H-shaped steel and the H-shaped steel is lifted up from the columnar improved body before hardening.

[0008] According to the construction method for a columnar improved body with a core material according to the first embodiment, in the dropping process, wall-like reinforcement, which is made by connecting multiple rod-shaped steel members with shear reinforcement bars, is placed on both sides of the web, and an H-shaped steel to which the upper part of the rod-shaped steel members is attached is dropped into the columnar improved body before hardening while being vibrated.

[0009] Next, in the lifting process, the upper part of the bar-shaped steel material is removed from the H-shaped steel, and the H-shaped steel is lifted from the columnar improved body before hardening. This embeds (remains in place of) the wall-shaped reinforcement inside the columnar improved body.

[0010] In this invention, by connecting multiple rod-shaped steel members with shear reinforcement bars to form a wall-like reinforcement, the shear strength of the columnar improved body can be ensured. Furthermore, by attaching the upper part of the rod-shaped steel members to an H-shaped steel beam, the positional displacement of the multiple rod-shaped steel members relative to the columnar improved body can be reduced.

[0011] Thus, the present invention makes it possible to ensure the shear strength of the columnar improved body while suppressing the displacement of the rod-shaped steel members relative to the columnar improved body.

[0012] The construction method for a columnar improved body with a core material according to the second embodiment is as follows: In the construction method for a columnar improved body with a core material according to the first embodiment, a pair of opposing positioning parts are provided at the lower end of the H-shaped steel; in the dropping step, the rod-shaped steel members of the wall reinforcement arranged on both sides of the web are connected by connecting reinforcing bars inserted between the pair of positioning parts, and the H-shaped steel is dropped into the columnar improved body before hardening while being vibrated; in the lifting step, the H-shaped steel is lifted from the columnar improved body before hardening, and the connecting reinforcing bars are removed from between the pair of positioning parts.

[0013] According to the construction method for a columnar improved body with a core material according to the second embodiment, a pair of opposing positioning parts are provided at the lower end of the H-shaped steel. Then, in the dropping process, the rod-shaped steel members of the wall reinforcement, which are arranged on both sides of the web of the H-shaped steel, are connected with connecting reinforcement inserted between the pair of positioning parts, and the H-shaped steel is dropped into the columnar improved body before hardening while being vibrated.

[0014] Next, in the lifting process, the H-shaped steel is lifted from the columnar improved body before hardening, and the connecting reinforcing bars are removed from between the pair of positioning sections. As a result, a pair of rod-shaped steel members are embedded (left in place) inside the columnar improved body.

[0015] Thus, in this invention, during the drop-in process, the movement of the connecting reinforcing bars and the multiple rod-shaped steel members connected by the connecting reinforcing bars is restricted by inserting connecting reinforcing bars between a pair of positioning parts. Therefore, misalignment of the rod-shaped steel members relative to the columnar improved body is further suppressed.

[0016] Furthermore, during the lifting process, the connecting reinforcing bars are removed from the pair of positioning sections by lifting the H-shaped steel. Therefore, the H-shaped steel can be easily lifted from the columnar improved body before hardening.

[0017] The construction method for a columnar improved body with a core material according to the third embodiment is, in the construction method for a columnar improved body with a core material according to the first or second embodiment, wherein in the dropping step, the upper part of the rod-shaped steel material is attached to a bracket protruding from the H-shaped steel material, and the H-shaped steel material is dropped into the columnar improved body before hardening while being vibrated, and in the lifting step, the upper part of the rod-shaped steel material is removed from the bracket, and the H-shaped steel material is lifted up from the columnar improved body before hardening.

[0018] According to the construction method for a columnar improved body with a core material according to the third embodiment, in the dropping process, the upper part of the rod-shaped steel material is attached to a bracket protruding from the H-shaped steel, and the H-shaped steel is dropped into the columnar improved body before hardening while being vibrated.

[0019] Next, in the lifting process, with the upper part of the rod-shaped steel removed from the bracket, the H-shaped steel is lifted from the columnar improved body before hardening.

[0020] By attaching the upper part of the rod-shaped steel material to the bracket protruding from the H-beam in this manner, the upper part of the rod-shaped steel material can be more firmly fixed to the H-beam. Therefore, when the H-beam is vibrated during the drop-in process, the vibration of the wall-like reinforcement is reduced, further reducing the displacement of the rod-shaped steel material relative to the columnar improved body.

[0021] A columnar improved body with a core material according to the fourth embodiment comprises a columnar improved body and a core material embedded in the columnar improved body, wherein the core material comprises a first wall-shaped reinforcement having a plurality of rod-shaped steel members and shear reinforcement bars connecting the plurality of rod-shaped steel members, a second wall-shaped reinforcement facing the first wall-shaped reinforcement, and a connecting reinforcement connecting the lower part of the rod-shaped steel members of the first wall-shaped reinforcement and the lower part of the rod-shaped steel members of the second wall-shaped reinforcement.

[0022] The fourth embodiment of the columnar improved ground with a core material comprises a columnar improved ground provided in the ground and a core material embedded in the columnar improved ground. The core material has a first wall-shaped reinforcement, a second wall-shaped reinforcement, and connecting reinforcement bars.

[0023] The first wall-shaped reinforcement has a plurality of bar-shaped steel materials and shear reinforcement bars that connect the plurality of bar-shaped steel materials. Similarly, the second wall-shaped reinforcement has a plurality of bar-shaped steel materials and shear reinforcement bars that connect the plurality of bar-shaped steel materials, and faces the first wall-shaped reinforcement. The lower parts of the bar-shaped steel materials of these first wall-shaped reinforcements and the lower parts of the bar-shaped steel materials of the second wall-shaped reinforcements are connected by connecting reinforcing bars.

[0024] Here, in the first wall-shaped reinforcement, the plurality of bar-shaped steel materials are connected by shear reinforcement bars. Also, in the second wall-shaped reinforcement, the plurality of bar-shaped steel materials are connected by shear reinforcement bars. By embedding these first wall-shaped reinforcements and second wall-shaped reinforcements in the columnar improvement body, the shear resistance of the columnar improvement body can be ensured.

[0025] Also, by connecting the lower parts of the bar-shaped steel materials of the first wall-shaped reinforcement and the lower parts of the bar-shaped steel materials of the second wall-shaped reinforcement with connecting reinforcing bars, when embedding the core material in the columnar improvement body, the displacement of the bar-shaped steel materials with respect to the columnar improvement body can be reduced.

[0026] Thus, in the present invention, while ensuring the shear resistance of the columnar improvement body, the displacement of the bar-shaped steel materials with respect to the columnar improvement body can be suppressed.

Effect of the Invention

[0027] As described above, according to the present invention, the displacement of the bar-shaped steel materials with respect to the columnar improvement body can be reduced.

Brief Description of the Drawings

[0028] [Figure 1] It is a vertical sectional view showing a columnar improvement body and a core material according to an embodiment. [Figure 2] It is a sectional view taken along line 2-2 of FIG. 1. [Figure 3] It is a perspective view of the core material shown in FIG. 1. [Figure 4] It is a vertical sectional view showing the construction process of a columnar improvement body according to an embodiment. [Figure 5] It is a sectional view taken along line 5-5 of FIG. 4. [Figure 6]Figure 4 is a perspective view showing the H-shaped steel and the lower part of the core material. [Figure 7] Figure 4 is a perspective view showing the upper part of the H-shaped steel and core material. [Figure 8] This is a vertical cross-sectional view showing the construction process of a columnar improved body according to one embodiment. [Figure 9] (A) and (B) are cross-sectional views corresponding to Figure 5, showing modified examples of the core material according to one embodiment. [Figure 10] This is an elevation view illustrating the loading method used in loading experiments. [Figure 11] (A) to (C) are elevation and cross-sectional views showing the experimental model used in the loading experiment. [Figure 12] This graph shows the experimental results of a loading experiment. [Modes for carrying out the invention]

[0029] An embodiment will be described below with reference to the drawings.

[0030] (Columnar improved body with core material) Figure 1 shows a columnar improved body with a core material according to this embodiment. The columnar improved body with a core material comprises a columnar improved body 10 and a core material 12 embedded in the columnar improved body 10.

[0031] (Columnar improved body) The columnar improved ground bodies (columnar ground improvement bodies) 10 are, for example, connected in a wall-like manner within the ground G, forming a retaining wall (not shown). These columnar improved ground bodies 10 are formed, for example, from hardened soil cement.

[0032] Specifically, the columnar improved body 10 is constructed by excavating the ground G with an excavation auger, injecting a cement-based hardening material such as cement grout into the ground G from the tip of the excavation auger, and hardening the soil cement formed by stirring and mixing the excavated soil and the cement-based hardening material underground.

[0033] Furthermore, on the side opposite to the side where earth pressure acts on the columnar improved body 10, underground spaces or underground structures (not shown) are formed. Also, the arrows P shown as appropriate in each figure indicate the direction of earth pressure acting on the columnar improved body 10 (the thickness direction of the columnar improved body 10 (retaining wall)), and the arrows W indicate the width direction of the columnar improved body 10 (retaining wall). In addition, the direction of earth pressure acting intersects (approximately perpendicular in this embodiment) with the width direction of the columnar improved body 10 in a plan view.

[0034] (Core material) A core material (core material for columnar improved soil) 12 is embedded inside the columnar improved soil body 10. The core material 12 is dropped into the columnar improved soil body 10 (soil cement) before it hardens, together with the H-shaped steel 30 (see Figure 4), which will be described later.

[0035] As shown in Figures 2 and 3, the core material 12 is provided with a pair of wall-like reinforcement bars 20. In a plan view, the pair of wall-like reinforcement bars 20 are arranged along the direction of earth pressure (direction of arrow P). These pair of wall-like reinforcement bars 20 are arranged opposite each other in the lateral direction of the columnar improved body 10 (see Figure 2). Note that the pair of wall-like reinforcement bars 20 is an example of a first wall-like reinforcement bar and a second wall-like reinforcement bar.

[0036] As shown in Figure 3, each wall-shaped reinforcement 20 has a pair of rod-shaped steel members 22 and corrugated shear reinforcement bars 24 connecting the pair of rod-shaped steel members 22. Each of the pair of rod-shaped steel members 22 is formed of straight reinforcing bars. The pair of rod-shaped steel members 22 extends vertically along the columnar improved body 10 and is spaced apart in the direction of earth pressure. This pair of rod-shaped steel members 22 is connected by corrugated shear reinforcement bars 24.

[0037] The corrugated shear reinforcement bars 24 are formed by curving straight reinforcing bars into a corrugated shape with alternating peaks facing opposite directions. These corrugated shear reinforcement bars 24 are arranged along the columnar improved body 10 and also extend across a pair of rod-shaped steel members 22. The peaks 24T of the corrugated shear reinforcement bars 24 are joined to the pair of rod-shaped steel members 22 by welding or other means. The pair of rod-shaped steel members 22 are connected by these corrugated shear reinforcement bars 24.

[0038] In this embodiment, the phases of the corrugated shear reinforcement bars 24 are opposite in one wall-like reinforcement bar 20 and the other wall-like reinforcement bar 20, but the phases of the corrugated shear reinforcement bars 24 may be the same, for example. Also, the corrugated shear reinforcement bars 24 are just one example of shear reinforcement bars.

[0039] The lower parts of a pair of bar-shaped steel members 22 in one wall-shaped reinforcement 20 and the lower parts of a pair of bar-shaped steel members 22 in the other wall-shaped reinforcement 20 are connected by a pair of connecting reinforcement bars 26. Specifically, the pair of bar-shaped steel members 22 in one wall-shaped reinforcement 20 and the pair of bar-shaped steel members 22 in the other wall-shaped reinforcement 20 face each other in the lateral direction (arrow W direction) of the columnar improved body 10.

[0040] Each of the pair of connecting reinforcing bars 26 is formed by a U-shaped reinforcing bar with an open top. These pairs of connecting reinforcing bars 26 are positioned opposite each other in the direction of earth pressure. Each connecting reinforcing bar 26 is positioned across the lower part of the opposing rod-shaped steel members 22 in the lateral direction of the columnar improved body 10, and is joined to the lower part of these rod-shaped steel members 22 by welding or the like. These connecting reinforcing bars 26 connect the lower part of the pair of rod-shaped steel members 22 in one wall-like reinforcement 20 to the lower part of the pair of rod-shaped steel members 22 in the other wall-like reinforcement 20.

[0041] (Construction method for columnar improved bodies with core material) Next, we will explain an example of a construction method for columnar improved bodies with core materials.

[0042] As shown in Figure 4, in this embodiment, the core material 12 is attached to the H-shaped steel beam 30, and the upper end of the H-shaped steel beam 30 is vibrated by a vibrator 80 such as a vibro-hammer, while the H-shaped steel beam 30 and the core material 12 are dropped into the columnar improved body 10 (soil cement) before hardening. Therefore, the attachment structure of the core material 12 to the H-shaped steel beam 30 will be described first.

[0043] (Mounting structure for core material to H-beam) As shown in Figure 5, the H-shaped steel beam 30 has a pair of flanges 32 that face each other in the direction of earth pressure and a web 34 that connects the pair of flanges 32. The H-shaped steel beam 30 is placed inside the columnar improved body 10 before hardening, with its longitudinal direction as the vertical direction and the direction in which the flanges 32 face each other as the direction of earth pressure.

[0044] A pair of wall-shaped reinforcement bars 20 are positioned on both sides of the web 34 of the H-shaped steel (temporary H-shaped steel) 30. As shown in Figure 6, the pair of wall-shaped reinforcement bars 20 are positioned to fit between the flanges 32 of the H-shaped steel 30. A pair of slits 40 are formed at the lower end of the web 34 of the H-shaped steel 30, into which a pair of connecting reinforcement bars 26 are inserted. The pair of slits 40 are spaced apart in the opposing direction of the flanges 32 (direction of arrow P).

[0045] Each slit 40 extends upward from the lower end of the web 34 and penetrates the web 34 in the thickness direction (direction of arrow W). Each slit 40 also has a pair of inner wall surfaces 40A that face each other in the direction opposite to the flange 32. The connecting reinforcing bar 26 is inserted into this slit 40. As a result, the pair of inner wall surfaces 40A of the slit 40 restrict the movement of the connecting reinforcing bar 26 in the direction opposite to the flange 32. Note that the pair of inner wall surfaces 40A is an example of a pair of positioning parts.

[0046] As shown in Figure 7, a pair of brackets 50 are provided on both sides of the web 34 of the H-shaped steel beam 30, to which the upper parts of a pair of bar-shaped steel members 22 are attached. In plan view, the pair of brackets 50 are formed by L-shaped angles. These brackets 50 are spaced apart in the direction opposite to the flange 32.

[0047] Each of the pair of brackets 50 has a base portion 52 that is joined to the surface of the web 34 by welding or the like while overlapping it, and a projection 54 that protrudes out of the plane of the web 34 from one end of the base portion 52. The projection 54 is formed in the shape of a wall facing the flange 32. A mounting reinforcing bar 60 is joined to the surface of this projection 54 by welding or the like.

[0048] The mounting bars 60 are formed from straight reinforcing bars and are arranged vertically. The lower ends of the mounting bars 60 extend downward from the protrusions 54 of a pair of brackets 50. The upper ends of a pair of rod-shaped steel members 22 in the wall-shaped reinforcement 20 are detachably connected to the lower ends of these mounting bars 60 via screw-type mechanical joints 62. In this way, the upper parts of the rod-shaped steel members 22 are fixed to the upper part of the H-shaped steel 30 via the mounting bars 60 and brackets 50.

[0049] (Positioning method) Next, a method for positioning the core material 12 relative to the columnar improved body 10 will be described.

[0050] Figure 4 shows the columnar improved body 10 (soil cement) formed in the ground G before hardening. A support frame 70 is provided around the columnar improved body 10 in the ground G. The support frame 70 has a pair of guide beams 72 that position the H-shaped steel 30 in the lateral direction of the columnar improved body 10, and a pair of guide pieces 74 that position the H-shaped steel 30 in the direction of earth pressure relative to the columnar improved body 10.

[0051] The pair of guide beams 72 are formed from, for example, H-shaped steel. The pair of guide beams 72 are spaced apart in the lateral direction of the columnar improved body 10 and are arranged parallel to each other. By inserting the H-shaped steel 30 with the core material 12 attached between the pair of guide beams 72, the H-shaped steel 30 is positioned in the lateral direction of the columnar improved body 10.

[0052] The pair of guide pieces 74 are formed, for example, from an angle iron, and are installed on the upper surface of the pair of guide beams 72. The pair of guide pieces 74 are spaced apart in the direction of the earth pressure (direction of arrow P) and are arranged parallel to each other. By inserting the H-shaped steel 30 with the core material 12 attached between the pair of guide pieces 74, the H-shaped steel 30 is positioned in the direction of the earth pressure relative to the columnar improved body 10.

[0053] (Dropping process) Next, the dropping process will be explained. In the dropping process, as described above, with the H-shaped steel beam 30 positioned relative to the columnar improved body 10, a vibrator 80 such as a vibro hammer attached to the upper end of the H-shaped steel beam 30 is activated, and the vibrator 80 vibrates the H-shaped steel beam 30 in the vertical direction. As a result, the H-shaped steel beam 30 and the core material 12 are guided by a pair of guide beams 72 and a pair of guide pieces 74, and are dropped (driven) into the interior of the columnar improved body 10 before hardening.

[0054] Next, when the lower ends of the H-shaped steel 30 and core material 12 reach a predetermined depth, the vibration exciter 80 is stopped. Note that each rod-shaped steel member 22 of the pair of wall-shaped reinforcements 20 is not embedded inside the columnar improved body 10, but is left exposed above ground.

[0055] (Lifting process) Next, the lifting process will be described. As shown in Figure 8, in the lifting process, first, the screw-type mechanical joint 62 is operated to release the connection between the mounting reinforcing bars 60 and the rod-shaped steel members 22, and the upper parts of each rod-shaped steel member 22 are removed from the H-shaped steel 30. This releases the fixing of the pair of wall-shaped reinforcing bars 20 to the H-shaped steel 30.

[0056] Next, the vibration exciter 80 is activated, and the H-shaped steel beam 30 is lifted while the upper end of the H-shaped steel beam 30 is vibrated. At this time, the connecting reinforcing bars 26 are pulled out from the pair of slits 40 formed at the lower end of the web 34 of the H-shaped steel beam 30. As a result, only the H-shaped steel beam 30 is removed from the columnar improved body 10, and the core material 12 is embedded inside the columnar improved body 10.

[0057] (effect) Next, the effects of this embodiment will be described.

[0058] According to the construction method for a columnar improved body with a core material as described in this embodiment, as shown in Figure 4, in the dropping process, the wall-shaped reinforcement bars 20 are arranged on both sides of the web 34, and the H-shaped steel 30 to which the upper parts of each rod-shaped steel material 22 of the wall-shaped reinforcement bars 20 are attached is dropped into the columnar improved body 10 before hardening while being vibrated.

[0059] Next, as shown in Figure 8, during the lifting process, the upper parts of each bar-shaped steel member 22 of the wall reinforcement 20 are removed from the H-shaped steel 30, and the H-shaped steel 30 is lifted from the columnar improved body 10 before hardening. As a result, a pair of wall reinforcement 20 is embedded (left in place) inside the columnar improved body 10. By reinforcing the columnar improved body 10 with this pair of wall reinforcement 20, damage to the columnar improved body 10 due to earth pressure is suppressed.

[0060] Furthermore, by connecting a pair of rod-shaped steel members 22 with corrugated shear reinforcement bars 24 to form a wall-shaped reinforcement bar 20, the shear strength of the columnar improved body 10 can be ensured. In addition, in this embodiment, steel material costs can be reduced compared to the case in which steel members such as H-shaped steel are used as the core material of the columnar improved body 10.

[0061] Furthermore, by attaching the upper part of each rod-shaped steel member 22 of the wall-shaped reinforcement 20 to the H-shaped steel 30, when the H-shaped steel 30 is vibrated during the dropping process, the vibration of the H-shaped steel 30 and the pair of wall-shaped reinforcement 20 attached to the H-shaped steel 30 is reduced, thereby reducing the positional displacement of each rod-shaped steel member 22 relative to the columnar improved body 10.

[0062] Thus, in this embodiment, it is possible to ensure the shear strength of the columnar improved body 10 while suppressing the positional displacement of each rod-shaped steel member 22 relative to the columnar improved body 10.

[0063] Furthermore, as shown in Figure 6, the lower part of the rod-shaped steel member 22 in one wall-shaped reinforcement 20 and the lower part of the rod-shaped steel member 22 in the other wall-shaped reinforcement 20 are connected by a connecting reinforcement bar 26. This further reduces the positional displacement of each rod-shaped steel member 22 relative to the columnar improved body 10 during the drop-in process.

[0064] Furthermore, during the dropping process, with the connecting reinforcing bars 26 inserted into the slits 40 formed at the lower end of the web 34 of the H-shaped steel 30, the H-shaped steel 30 is dropped into the columnar improved body 10 before hardening while being vibrated.

[0065] As a result, the pair of inner wall surfaces 40A of the slit 40 restrict the movement of the connecting reinforcing bars 26 in the opposing direction of the flange 32. Therefore, the positional displacement of the lower part of each rod-shaped steel member 22 relative to the columnar improved body 10 is reduced.

[0066] Furthermore, as shown in Figure 7, in the dropping process, the upper part of the rod-shaped steel material 22 is attached to the mounting reinforcing bar 60 fixed to the bracket 50 protruding from the web 34 of the H-shaped steel 30, and the H-shaped steel 30 is dropped into the columnar improved body 10 before hardening while being vibrated.

[0067] By attaching the upper part of the rod-shaped steel member 22 to the bracket 50 protruding from the web 34 of the H-shaped steel 30 in this manner, the upper part of the rod-shaped steel member 22 can be more firmly fixed to the H-shaped steel 30. Therefore, when the H-shaped steel 30 is vibrated during the drop-in process, the vibration of the wall-like reinforcement 20 is further reduced, and the displacement of the rod-shaped steel member 22 relative to the columnar improved body 10 is further reduced.

[0068] Furthermore, the upper end of the rod-shaped steel member 22 is detachably connected to the lower end of the mounting reinforcing bar 60 via a screw-type mechanical joint 62. Therefore, the upper part of the rod-shaped steel member 22 can be easily removed from the mounting reinforcing bar 60 during the lifting process.

[0069] Furthermore, as shown in Figure 5, the pair of wall-shaped reinforcements 20 are positioned to fit between the flanges 32 of the H-shaped steel 30. As a result, even if the vibration (amplitude) of the bar-shaped steel member 22 becomes large, the vibration of the bar-shaped steel member 22 is limited because the bar-shaped steel member 22 comes into contact with the web 34 or flange 32 of the H-shaped steel 30.

[0070] Furthermore, as shown in Figure 6, in the lifting process, the connecting reinforcing bars 26 can be easily removed from the slit 40 by lifting the H-shaped steel 30 from the columnar improved body before hardening. Therefore, the H-shaped steel 30 can be easily lifted from the columnar improved body 10.

[0071] Furthermore, as shown in Figure 3, in this embodiment, a pair of bar-shaped steel members 22 are connected by a single corrugated shear reinforcement bar 24. However, if, for example, a pair of bar-shaped steel members 22 were connected in a ladder-like manner using multiple linear shear reinforcement bars, it would be necessary to position the multiple linear shear reinforcement bars at predetermined intervals relative to the pair of bar-shaped steel members 22, which would make the positioning of the shear reinforcement bars time-consuming.

[0072] In contrast, in this embodiment, since one corrugated shear reinforcement bar 24 is positioned relative to a pair of rod-shaped steel members 22, the corrugated shear reinforcement bar 24 can be easily positioned relative to the pair of rod-shaped steel members 22. Furthermore, by welding the top portion 24T of the corrugated shear reinforcement bar 24 to the pair of rod-shaped steel members 22, the corrugated shear reinforcement bar 24 can be easily attached to the pair of rod-shaped steel members 22.

[0073] (modified version) Next, a modified example of the above embodiment will be described.

[0074] In the above embodiment, two rod-shaped steel members 22 are connected by corrugated shear reinforcement bars 24. However, the number of rod-shaped steel members 22 is not limited to two; three or more rod-shaped steel members 22 may be connected by corrugated shear reinforcement bars 24. For example, in the modified example shown in Figure 9(A), three rod-shaped steel members 22 arranged in the direction of earth pressure (direction of arrow P) are connected by corrugated shear reinforcement bars 24.

[0075] Furthermore, in the above embodiment, the pair of wall-shaped reinforcements 20 are arranged to fit between the flanges 32 of the H-shaped steel 30. However, as shown in the modified example in Figure 9(B), the pair of wall-shaped reinforcements 20 may be arranged on the outside between the flanges 32 of the H-shaped steel 30. In this case, for example, the protruding portion 54 of the bracket 50 protrudes outward beyond the flanges 32 of the H-shaped steel 30, and the mounting reinforcement 60 is fixed to the tip of the protruding portion 54.

[0076] Furthermore, in the above embodiment, the rod-shaped steel material 22 was detachably connected to the mounting reinforcing bar 60 via a screw-type mechanical joint 62 during the dropping process. However, for example, during the dropping process, a filler material such as grout may be filled into the mechanical joint 62, and the rod-shaped steel material 22 may be detachably connected to the mounting reinforcing bar 60. In this case, during the lifting process, the upper part of the rod-shaped steel material 22 is removed from the H-shaped steel 30 by cutting, for example, the mounting reinforcing bar 60 or the rod-shaped steel material 22.

[0077] Alternatively, for example, during the dropping process, the upper part of the rod-shaped steel material 22 may be directly fixed to the protruding part 54 of the bracket 50 by welding or the like, and during the lifting process, the upper part of the rod-shaped steel material 22 may be removed from the H-shaped steel material 22 by cutting the rod-shaped steel material 22.

[0078] Furthermore, the bracket 50 is not limited to an angle; for example, it may be made of C-shaped steel or T-shaped steel. Also, the bracket 50 is not limited to being fixed to the web 34 of the H-shaped steel 30; it may be fixed to the flange 32.

[0079] Furthermore, in the above embodiment, a pair of rod-shaped steel members 22 were connected by corrugated shear reinforcement bars 24. However, the pair of rod-shaped steel members 22 may also be connected in a ladder-like manner by a plurality of straight shear reinforcement bars.

[0080] Furthermore, in the above embodiment, the rod-shaped steel material 22 is a straight reinforcing bar. However, the rod-shaped steel material may also be a flat bar, an angle, or the like.

[0081] Furthermore, in the above embodiment, a pair of positioning parts is provided, which are slits 40 formed at the lower end of the web 34 of the H-shaped steel 30. However, the pair of positioning parts are not limited to slits 40, but may also be, for example, a pair of angles attached to the lower end of the H-shaped steel 30 and facing each other in the direction opposite to the flange 32. In this case, connecting reinforcement bars 26 are placed between the pair of angles. Also, the connecting reinforcement bars 26 are not limited to U-shaped reinforcement bars, but may also be, for example, C-shaped reinforcement bars or straight reinforcement bars.

[0082] The pair of slits 40 may be provided as needed and can be omitted as appropriate. Similarly, the pair of connecting reinforcing bars 26 may be provided as needed and can be omitted as appropriate.

[0083] (Loading experiment) Next, we will explain the loading experiment on the columnar improved body.

[0084] In this loading experiment, a loading experiment was performed on an experimental model of a columnar improved body 10 in which a core material 12 was embedded, in order to confirm the shear reinforcement effect of the corrugated shear reinforcement bars 24.

[0085] (Experiment Overview) As shown in Figure 10, in this loading experiment, the longitudinal ends of the experimental model were pinned from below by support points S, and a vertical load N, representing earth pressure, was applied to the longitudinal center of the experimental model. The displacement (deflection) of the center of each experimental model was then measured. Figure 10 also shows experimental model M2, which will be described later.

[0086] (Experimental model) Figures 11(A) to 11(C) show experimental models M1 to M3. In each experimental model M1 to M3, multiple rod-shaped steel members 92 are embedded inside a prismatic columnar improved body 90 formed of soil cement. The ends of the multiple rod-shaped steel members 92 are each tied together with positioning stirrups 100. These stirrups 100 are positioned outside the support points S so as not to affect the shear strength of each experimental model M1 to M3.

[0087] In experimental model M1 shown in Figure 11(A), no shear reinforcement is provided. In experimental model M2 shown in Figure 11(B), a pair of rod-shaped steel members 92 facing each other in the vertical direction (direction of earth pressure) are connected by corrugated shear reinforcement bars 94. In experimental model M3 shown in Figure 11(C), multiple rod-shaped steel members 92 are surrounded by strip-shaped shear reinforcement bars (hoop bars) 96.

[0088] (Experimental results) Figure 12 shows the experimental results for experimental models M1 to M3. In the graphs shown in Figure 12, the vertical axis represents the vertical load N applied to the central part of each experimental model M1 to M3, and the horizontal axis represents the deformation amount at the central part of each experimental model M1 to M3.

[0089] As can be seen in Figure 12, in experimental model M1, which did not have shear reinforcement, shear failure occurred prematurely. In contrast, in experimental model M2, which was equipped with corrugated shear reinforcement 94, and experimental model M3, which was equipped with strip shear reinforcement 96, premature shear failure was prevented. This confirms the shear reinforcement effect of corrugated shear reinforcement 94 and strip shear reinforcement 96.

[0090] Furthermore, the shear strength of experimental model M2, which was equipped with corrugated shear reinforcement 94, was slightly lower than that of experimental model M3, which was equipped with strip-shaped shear reinforcement 96, but the result was comparable to that of experimental model M3. This confirms the usefulness of corrugated shear reinforcement 94.

[0091] Although one embodiment of the present invention has been described above, the present invention is not limited to these embodiments, and various modifications may be used in appropriate combinations with one embodiment, and of course, the invention can be implemented in various forms without departing from the spirit of the present invention. [Explanation of Symbols]

[0092] 10 Improved columnar body 12 Core material 20 Wall muscle (first wall muscle, second wall muscle) 22 Steel bars 24. Corrugated shear reinforcement (shear reinforcement) 26 connecting reinforcing bars G Ground

Claims

1. Columnar improved bodies installed in the ground, The core material embedded in the columnar improved body, Equipped with, The aforementioned core material is A first wall-like reinforcement having multiple rod-shaped steel members and shear reinforcement bars connecting the multiple rod-shaped steel members, It comprises a plurality of rod-shaped steel members and shear reinforcement bars connecting the plurality of rod-shaped steel members, and a second wall-shaped reinforcement bar facing the first wall-shaped reinforcement bar, A connecting reinforcing bar is joined to the lower part of the rod-shaped steel material of the first wall-shaped reinforcing bar and to the lower part of the rod-shaped steel material of the second wall-shaped reinforcing bar, connecting the lower parts of each other. Having, Columnar improved body with core material.

2. A columnar improved body provided in the ground, The core material embedded in the columnar improved body, Equipped with, The aforementioned core material is A first wall-like reinforcement having multiple rod-shaped steel members and shear reinforcement bars connecting the multiple rod-shaped steel members, It comprises a plurality of rod-shaped steel members and shear reinforcement bars connecting the plurality of rod-shaped steel members, and a second wall-shaped reinforcement bar facing the first wall-shaped reinforcement bar, A connecting reinforcing bar that connects the lower part of the rod-shaped steel material of the first wall-shaped reinforcing bar and the lower part of the rod-shaped steel material of the second wall-shaped reinforcing bar, It has, The connecting reinforcement is a U-shaped reinforcement with an open upper side. Columnar improved body with core material.

3. The shear reinforcement bars of the first wall-like reinforcement bar and the second wall-like reinforcement bar are wave-shaped shear reinforcement bars. A columnar improved body with a core material according to claim 1 or claim 2.

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