JP6875751B2 - Ground reinforcement steel pipe and ground reinforcement method using this - Google Patents

Description

The present invention relates to a steel pipe for ground reinforcement used for tunnel excavation and the like, and a ground reinforcement method using the same.

In tunnel excavation work, a steel pipe for reinforcement of the ground is inserted into the ground, and after reinforcing the ground by injecting a binder from this steel pipe for reinforcement of the ground, the steel pipe for reinforcement of the ground is inserted. Proceed with excavation of the ground. Every time the end of the ground reinforcing steel pipe is exposed by excavation of the ground, any exposed part of the ground reinforcing steel pipe is hit with a construction machine such as a breaker to separate and remove it.

A steel pipe having a groove for cutting along the circumferential direction of the ground reinforcing steel pipe is known in order to facilitate the separation when the ground reinforcing steel pipe is removed (for example, Patent Documents 1 to 4). ). Patent Document 1 discloses a groove having a quadrangular cross section, and Patent Document 2 discloses a groove having a ∨-shaped cross section. These documents disclose grooves having various shapes. The steel pipes disclosed in Patent Documents 3 and 4 are provided with slits for dividing the steel pipe in the axial direction over at least the entire length of the region partitioned by the adjacent grooves.

Japanese Unexamined Patent Publication No. 2000-314291 Japanese Unexamined Patent Publication No. 2000-145398 Japanese Unexamined Patent Publication No. 2007-146498 Japanese Unexamined Patent Publication No. 2011-153402

However, the conventional steel pipe for reinforcing the ground is often deformed without being separated cleanly in the groove even if it is hit. It took time to remove the deformed ground reinforcement steel pipe.

An object of the present invention is to provide a ground reinforcing steel pipe that can be easily separated when it is hit.

In order to solve the above problems, one aspect of the present invention is a ground reinforcing steel pipe for inserting into the ground and injecting a solidifying agent into the ground, at least one location in the longitudinal direction in the circumferential direction. Along the line, a groove portion for cutting is provided, and a ring-shaped member is arranged in the groove portion.

Another aspect of the present invention is a steel pipe for reinforcing the ground, which is inserted into the ground to inject a solidifying agent into the ground, and is cut at at least one position in the longitudinal direction along the circumferential direction. The groove portion has a groove portion for use, and the groove portion has a notch portion in the depth direction of the groove portion formed at the bottom thereof.

According to the present invention, the ground reinforcing steel pipe can be easily separated when it is hit.

(A) A perspective view of the ground reinforcing steel pipe of the present invention, (B) an enlarged cross section of the ground reinforcing steel pipe along the longitudinal direction, (C) a plan view of the ring 3, and (D) a blow. The figure which shows the force which sometimes acts on the steel pipe for ground reinforcement. (A) to (C) are enlarged views of cross sections showing deformation examples of the groove portions, respectively. (A) A side view of the ground reinforcing steel pipe of the first embodiment, and (B) a side view showing a configuration example of one steel pipe. (A) to (C) are side views which show the ground reinforcement steel pipe of each modification. The graph which shows the result of the bending test about the steel pipe for ground reinforcement of Examples 1 to 3 and the comparative example. A perspective view of the steel pipe for reinforcing the ground of the second embodiment, an enlarged view of a cross section of the pipe, and a view showing a force acting when a striking force is applied. The graph which shows the result of the bending test about the steel pipe for ground reinforcement of Example 4 and the comparative example. FIG. 3 is an enlarged view of (A) a cross section of the ground reinforcing steel pipe of the third embodiment, and (B) a diagram showing a force acting when a hit is applied. The graph which shows the result of the bending test about the steel pipe for ground reinforcement of Example 5 and the comparative example. The figure which shows the reinforcement method of the ground.

[Steel pipe for ground reinforcement]
An embodiment of the ground reinforcing steel pipe of the present invention will be described.

<First Embodiment>
As shown in FIG. 1A, the ground reinforcing steel pipe 10 has a groove portion 2 for cutting along the circumferential direction thereof, and the groove portion 2 has a ring-shaped member 3 (hereinafter referred to as “ring 3”). Have been placed.

The cross-sectional shape of the groove portion 2 is not particularly limited, but is, for example, a quadrangle as shown in FIG. 1 (B). The depth t1 of the groove portion 2 is preferably 20% to 70% with respect to the wall thickness T of the steel pipe. Further, the width of the groove portion 2 has a size such that the ring 3 can be arranged, and is about 1 mm to 10 mm. The cross-sectional shape of the groove portion 2 is not limited to a quadrangle, and may have a V-shape or a U-shape, for example, as shown in FIGS. 2A to 2B. Further, the cross-sectional shape of the groove portion 2 may have a shape in which the above-mentioned shapes are combined. For example, as shown in FIG. 2C, the cross-sectional shape is a shape in which a V-shaped groove is formed at the bottom of the quadrangular groove. There may be.

The ring 3 is in contact with the bottom of the groove 2 at at least one point. There are no particular restrictions on the cross-sectional shape of the ring 3, but it is preferable to make the ring 3 as large as possible according to the width of the groove 2 because the impacted ground reinforcing steel pipe 10 can be more easily separated. Specifically, the cross-sectional shape of the ring 3 may be a quadrangle as in the groove portion 2, or may have various shapes such as a triangle, a circle, and an ellipse as shown in FIGS. Good.

As shown in FIG. 1 (B), the width of the ring 3 is slightly narrower than the width of the groove portion 2, and is preferably 70% or more of the width of the groove portion 2. The dimension t2 of the groove portion 2 of the ring 3 in the depth direction is preferably equal to or less than the depth t1 of the groove portion 2. As a result, the ring 3 is arranged so as not to protrude from the outer peripheral end of the steel pipe 10, so that the peripheral surface of the ground reinforcing steel pipe 10 has no unevenness and the ring 3 is arranged in the groove portion 2. Reinforcing steel pipes can be smoothly inserted into the ground.

The material constituting the ring 3 is, but is not limited to, steel, stainless steel, high-strength resin, and the like. The ring 3 may be arranged in the groove 2 by winding the wire around the groove 2 of the ground reinforcing steel pipe 10, or the ring 3 originally having a ring shape as shown in FIG. 1 (C) is the groove 2. You may fit it.

The rigidity of the ring 3 is equal to or higher than the rigidity of the material constituting the main body of the ground reinforcing steel pipe 10. As a result, it is possible to prevent the ring 3 itself from being deformed even if an impact is applied when the ground reinforcing steel pipe 10 is cut, so that the ground reinforcing steel pipe 10 can be more easily separated.

The ring 3 does not have to be arranged over the entire circumference of the groove portion 2, and the ring 3 is formed on the groove portion 2 with respect to the portion of the groove portion 2 closest to the portion to which the impact D is applied when cutting the ground reinforcing steel pipe 10. It suffices if it is arranged at least on the opposite side in the radial direction. Specifically, the ring 3 is preferably arranged in a range of 200 degrees or more and 360 degrees or less of the groove portion 2 when the circumference of the groove portion 2 is 360 degrees.

When the impact D is applied to the ground reinforcing steel pipe 10, as shown in FIG. 1 (D), the groove 2 contracts on the opposite side of the portion that receives the impact D, and the side surface of the groove 2 and the ring 3 come into contact with each other. Since the portion in contact with the ring 3 and the side surface of the groove portion 2 serves as a fulcrum of the lever principle, a force is applied in the direction of arrow y1 to separate the ground reinforcing steel pipe 10.

As described above, the ground reinforcing steel pipe of the present embodiment can be easily separated because the ring acts as a fulcrum of the lever principle on the opposite side of the impacted portion. As a result, it is possible to reduce the time and burden required for the removal work of the ground reinforcing steel pipe. Further, since the ground reinforcing steel pipe is separated without being deformed, the separated ground reinforcing steel pipe can be reused.

The basic structure of the ground reinforcing steel pipe of the first embodiment has been described above. Hereinafter, a more specific structure will be described.

As shown in FIG. 3, the ground reinforcing steel pipe 10 of the present embodiment is composed of a plurality of steel pipes connected via a connecting portion, and a plurality of grooves are formed in each steel pipe, and a ring is formed in each groove. Is placed. In the illustrated example, in the ground reinforcing steel pipe 10, four steel pipes 101 to 104 are connected via a connecting portion 4.

In the following description, the side to be inserted into the ground is the leading steel pipe 101, and the opposite side, the side to be first exposed when excavating after insertion, is the terminal steel pipe 104. Four groove portions 2 are provided in each of the steel pipes 101 to 104 at predetermined intervals, and a ring 3 is arranged in each groove portion 2. The structure of the groove portion 2 and the ring 3 is the same as the above-described structure.

Hereinafter, the configuration of the connecting portion 4 will be described with reference to the steel pipe 101 because the configurations of the steel pipes 101 to 104 are the same. As shown in FIG. 3B, a female screw portion 4A is formed on the inner circumference on one end side of the steel pipe 101, and a male screw portion 4B is formed on the outer circumference on the other end side. The diameter of the male threaded portion 4B side of the steel pipe 101 is smaller than that of the other portions, and the male threaded portion 4B is screwed in the female threaded portion 4A of the adjacent steel pipe 102 to connect the steel pipe 101 and the steel pipe 102.

According to this configuration, the connecting portion 4 can connect as many steel pipes as necessary according to the depth of excavation. Further, since the groove and the ring are arranged over the entire ground reinforcing steel pipe, the steel pipe can be separated diligently according to the progress of excavation.

<Modification example 1>
The ground reinforcing steel pipe 10 of FIG. 3 has a configuration in which a groove 2 and a ring 3 are provided in all of the plurality of ground reinforcing steel pipes 10, but the ground reinforcing steel pipe 10 is composed of a plurality of steel pipes. In this case, the groove 2 and the ring 3 may be provided at at least one of the plurality of steel pipes at one or more locations. For example, as shown in FIG. 4A, the groove 2 and the ring 3 may be arranged only on the terminal-side steel pipe 104 that is first exposed when the ground is excavated after the ground reinforcing steel pipe 10 is inserted. Good.

<Modification 2>
As shown in FIG. 4B, each steel pipe may be provided with a slit 5 extending in the axial direction. The slits 5 are arranged at positions facing each other in the radial direction with the axial center of the steel pipe interposed therebetween, and it is preferable that the slits 5 adjacent to each other in the longitudinal direction of the steel pipe are arranged so as not to overlap each other by 90 degrees. .. Further, the slit 5 has a length that connects at least the adjacent groove portions 2.

When a force is applied to the slit 5 of the exposed steel pipe when excavating the ground after insertion, the steel pipe can be divided into two in the axial direction. Therefore, even if the binder is stuck or adhered to the inside of the steel pipe, the binder and the steel pipe can be easily separated. By separating the steel pipe from the binder, the separated steel pipe can be reused.

It is more preferable that each slit 5 has a length such that the end portion thereof slightly exceeds the groove portion 2 because the steel pipe can be reliably separated into two. The number of slits is not limited to two provided at opposite positions in the radial direction, and two or more slits may be arranged as long as the steel pipe can be divided in the axial direction. Further, the slit 5 may not be arranged in the region of the steel pipe where the binder is not injected.

By arranging the slit 5, the binder injected into the steel pipe can be evenly discharged to the ground. Instead of providing the slit 5 in the ground reinforcing steel pipe 10, a discharge hole 51 (see FIG. 4 (A)) penetrating in the radial direction of the steel pipe is provided in order to allow the solidifying agent in the steel pipe to flow out toward the ground. It may be provided.

<Modification example 3>
The groove 2 and the ring 3 may be provided in the connecting portion 4 as shown in FIG. 4 (C). At this time, the groove portion 2 is provided on the steel pipe side arranged on the outer peripheral side of the connecting portion 4 among the adjacent steel pipes.

The configurations of the steel pipes 101 to 104 may be different from each other. The female screw portion 4A may not be provided at the tip of the steel pipe 101, or the male screw portion 4B may not be provided at the end of the steel pipe 104. Further, the configuration of the connecting portion 4 connecting the adjacent steel pipes is not limited to the configuration as described above, and the adjacent steel pipes may be connected by welding.

Hereinafter, the bending test performed by the inventors to confirm that the steel pipe 10 for reinforcing the ground of the first embodiment is easily cut when hit is described.

[Preparation of steel pipe]
As the ground reinforcing steel pipes of Examples 1 to 3 and Comparative Example 1, steel pipes having an outer diameter of 114.3 mm and a thickness of 3.5 mm were prepared. The cross-sectional shape of the groove of each steel pipe was quadrangular, and the width was 3.5 mm. A plurality of such steel pipes having different groove depths were prepared. Rings having different cross-sectional shapes or sizes were arranged in the grooves of the steel pipes of Examples 1 to 3, and no rings were arranged in the steel pipes of Comparative Example 1. A ring having a circular cross-sectional shape and a diameter of 2.6 mm was arranged in the ground reinforcing steel pipe of Example 1. A ring having a circular cross-sectional shape and a diameter of 3.2 mm was arranged in the ground reinforcing steel pipe of Example 2. A ring having a quadrangular cross section of 3.4 mm square was arranged in the ground reinforcing steel pipe of Example 3.

[Test method for bending test]
For the ground reinforcing steel pipes of Examples 1 to 3 and Comparative Example 1, one end of the ground reinforcing steel pipe is fixed to the testing machine table by using an Amsler type universal testing machine, and the other end is pushed by a pushing jig. A load was applied and the load (kN) at break was measured. Further, with respect to the ground reinforcing steel pipes of Examples 1 and 2 and Comparative Example 1, the depth of the groove was changed and how the load at the time of fracture changed was measured.

[result]
The horizontal axis of the graph shown in FIG. 5 indicates the residual wall thickness (mm) obtained by subtracting the depth of the groove from the thickness of the steel pipe. The vertical axis of this graph shows the breaking load (kN) when the steel pipe is cut by being pushed. The dotted line in this graph is an approximate straight line of the breaking load value at each residual wall thickness of the ground reinforcing steel pipe of Comparative Example 1.

As shown in this graph, when the residual wall thickness is 1.3 mm, the ground reinforcing steel pipes of Examples 1 and 2 may break with a smaller force than the ground reinforcing steel pipe of Comparative Example 1. all right. Further, it was found that when the residual wall thickness was 1.17 mm, the ground reinforcing steel pipe of Example 3 broke with a smaller force than the ground reinforcing steel pipe of Comparative Example 1. As for the other residual wall thickness, it was found that the ground reinforcing steel pipes of Examples 1 to 3 broke with a smaller force than the ground reinforcing steel pipe of Comparative Example 1. From this result, it was found that the ground reinforcing steel pipe of the first embodiment in which the ring is arranged in the groove can be cut with a smaller force than the ground reinforcing steel pipe in which the ring is not arranged in the groove. It was.

<Second Embodiment>
Hereinafter, the difference between the ground reinforcing steel pipe 10B of the second embodiment and the ground reinforcing steel pipe 10 of the first embodiment will be described. As shown in FIG. 6, the ground reinforcing steel pipe 10B is characterized in that a notch 6 in the depth direction of the groove 2 is formed at the bottom of the groove 2. The shape and depth of the groove portion 2 are the same as those in the first embodiment.

The cutout portion 6 is formed in a direction (that is, along the groove portion 2) orthogonal to the axial direction of the ground reinforcing steel pipe 10 at a substantially central portion of the bottom portion of the groove portion 2. The depth t3 of the notch portion 6 is not limited, but is preferably 1% to 20% of the depth t1 of the groove portion 2 as shown in FIG. 6 (B). As described above, the notch portion 6 is formed at the bottom of the groove portion 2 to the extent that it does not affect the wall thickness of the ground reinforcing steel pipe 10, and is shown in FIGS. 2 (B) and 2 (C). It is different from such a V-shaped groove.

The cutout portion 6 is preferably provided over the entire circumference of the groove portion 2, but may be provided in a range of at least 240 degrees or more and 360 degrees or less of the groove portion 2. A plurality of notches 6 may be provided for one groove 2, or may be discontinuously cut in one groove 2.

When the impact D is applied to the ground reinforcing steel pipe 10B, as shown in FIG. 6C, a tensile force acts on the portion of the notch 6 closest to the portion where the impact D is applied, and the force is applied in the direction of arrow y2. The steel pipe 10B for reinforcing the ground is separated.

As described above, the ground reinforcing steel pipe of the second embodiment can be easily separated because a tensile force acts on the notch when it is hit. Therefore, it is possible to reduce the time and burden required for the removal work of the ground reinforcing steel pipe. Further, since the ground reinforcing steel pipe is separated without being deformed, the separated ground reinforcing steel pipe can be reused.

Hereinafter, the bending test performed by the inventors to confirm that the steel pipe 10B for reinforcing the ground of the second embodiment is easily cut when hit is described.

[Preparation of steel pipe]
As the ground reinforcing steel pipe of Example 4, the ground reinforcing steel pipe of the second embodiment was prepared. The outer diameter of the ground reinforcing steel pipe of Example 4 was 114.3 mm, and the thickness was 3.5 mm. The shape of the groove portion of the ground reinforcing steel pipe of Example 4 was quadrangular, and the width thereof was 3.0 mm. A notch having a depth of 0.2 mm was formed at the bottom of the groove of the steel pipe of Example 4. No ring was placed in the groove of the steel pipe of Example 4. A plurality of such ground reinforcing steel pipes of Example 4 and the above-mentioned ground reinforcing steel pipe of Comparative Example 1 having different depths of grooves were prepared.

[Test method for bending test]
For the ground reinforcing steel pipes of Example 4 and Comparative Example 1, an Amsler type universal testing machine was used, one end of the ground reinforcing steel pipe was fixed to the testing machine table, and the other end was pushed by a pushing jig to apply a load. The load (kN) at the time of application and breakage was measured.

[result]
As shown in FIG. 7, it was found that the ground reinforcing steel pipe of Example 4 was broken with a smaller force than the ground reinforcing steel pipe of Comparative Example 1 regardless of the residual wall thickness. It was. As a result, the ground reinforcing steel pipe of the second embodiment having a notch in the groove can be cut with a smaller force than the ground reinforcing steel pipe having no notch in the groove. I understood.

<Third Embodiment>
In the ground reinforcing steel pipe 10C of the third embodiment, as shown in FIG. 8A, the notch 6 is formed at the bottom of the groove 2, and the ring 3 is arranged in the groove 2. It is a feature.

The configuration and action of the ring 3 are the same as the configuration and action of the ring 3 described in the first embodiment, and the configuration and action of the notch 6 are the same as the configuration and action of the notch 6 described in the second embodiment. is there.

Since the groove portion 2 of the ground reinforcing steel pipe 10C is provided with both the ring 3 and the notch portion 6, as shown in FIG. 8 (B), on the opposite side of the portion of the steel pipe that has been hit by the impact D. The portion in contact with the side surface of the ring 3 and the groove portion 2 serves as a fulcrum of the lever principle, and a force is applied in the direction of arrow y1. work. As a result, the ground reinforcing steel pipe 10C can be separated more easily.

Hereinafter, the bending test performed by the inventors to confirm that the steel pipe 10C for reinforcing the ground of the third embodiment is easily cut when hit is described.

[Preparation of steel pipe]
As the ground reinforcing steel pipe of Example 5, the ground reinforcing steel pipe of the third embodiment was prepared. The outer diameter of the ground reinforcing steel pipe of Example 5 was 114.3 mm, and the thickness was 3.5 mm. The shape of the groove portion of the ground reinforcing steel pipe of Example 5 was quadrangular, and the width thereof was 3.0 mm. A notch having a depth of 0.2 mm was formed at the bottom of the groove of the ground reinforcing steel pipe of Example 5. A quadrangular ring having a cross section of 2.5 mm was arranged in the groove of the ground reinforcing steel pipe of Example 5. As for the ground reinforcing steel pipe of Example 5 and the ground reinforcing steel pipe of Comparative Example 1, a plurality of steel pipes having different groove depths were prepared.

[Test method for bending test]
For the ground reinforcing steel pipes of Example 5 and Comparative Example 1, an Amsler type universal testing machine was used, one end of the ground reinforcing steel pipe was fixed to the testing machine table, and the other end was pushed by a pushing jig to apply a load. The load (kN) at the time of application and breakage was measured.

[result]
As shown in FIG. 9, it was found that the ground reinforcing steel pipe of Example 5 was broken with a smaller force than the ground reinforcing steel pipe of Comparative Example 1 regardless of the residual wall thickness. It was. As a result, the steel pipe for ground reinforcement of the third embodiment, in which the groove is provided with a notch and the groove is provided with a ring, has no notch or ring in the groove to reinforce the ground. It was found that it can be cut with less force than steel pipes.

The above-described embodiments and modifications can be combined within a technically consistent range and are included in the present invention.

[Ground reinforcement method]
Next, a method for reinforcing the ground when excavating a tunnel using the steel pipe for reinforcing the ground of the present invention will be described. Here, a case where the ground reinforcing steel pipe of the first embodiment in which the ring is arranged in the groove is used will be illustrated.

(Step 1)
As shown in FIG. 10 (A), the ground reinforcing steel pipe 10 is inserted into the ground G in the direction of the arrow Y, and the solidifying agent is injected into the ground reinforcing steel pipe 10. A known method can be used as a method for inserting the ground reinforcing steel pipe 10 into the ground G. When the ground reinforcing steel pipe 10 is provided with a discharge hole 51 for discharging the solidifying agent, the injected solidifying agent flows out to the ground from the discharge hole 51 penetrating in the radial direction of the steel pipe. Alternatively, when the slit 5 (FIG. 4 (B)) is provided in the ground reinforcing steel pipe 10, the binder flows out from the slit 5 to the ground. The solidifying agent injected in this way solidifies inside and outside the ground reinforcing steel pipe 10, and the ground is reinforced.

(Step 2)
As shown in FIG. 10B, the ground G is excavated using the excavator E. At the time of excavation, the soil around the steel pipe is removed to expose the steel pipe 104 on the terminal side.

(Step 3)
When the groove 2 is exposed by excavation, as shown in FIG. 10C, when a blow D is applied to the terminal side of the exposed groove 2 with a breaker or the like, the ground reinforcing steel pipe 10 is cut at the groove 2. To. Specifically, since the ring 3 is arranged in the groove portion 2, the groove portion 2 contracts on the opposite side of the portion that has been hit by the impact D, and the side surface of the groove portion 2 and the ring 3 come into contact with each other. The portion in contact with the side surface serves as a fulcrum of the lever principle, and a force is applied in the direction of arrow y1 to separate the ground reinforcing steel pipe 10.

As described above, in the main ground reinforcement method, the ring acts as a fulcrum of the lever principle on the opposite side of the hit portion, so that the ground reinforcement steel pipe can be easily separated. As a result, it is possible to reduce the time and burden required for the removal work of the ground reinforcing steel pipe. Further, since the ground reinforcing steel pipe is separated without being deformed, the separated ground reinforcing steel pipe can be reused.

When the ground reinforcing steel pipe 10 is provided with the slit 5 as shown in FIG. 4 (B), a blow D is applied in step 3 to separate the ground reinforcing steel pipe 10, and then the slit 5 is pushed open. When the ground reinforcing steel pipe 10 is pressed in this way, the ground reinforcing steel pipe 10 is divided in the axial direction. As a result, the solidifying agent and the ground reinforcing steel pipe 10 are separated, so that the ground reinforcing steel pipe 10 can be reused.

When inserting the ground, a steel pipe for reinforcing the ground may be used in which the ring 3 is not arranged in the groove 2. In this case, the step of arranging the ring 3 in the groove 2 is performed after injecting the binder and excavating the ground, and the ring 3 is arranged with respect to the groove 2 for cutting located outside the ground. To. Even when the ring 3 was placed after inserting the ground reinforcing steel pipe into the ground, it was hit in the same manner as when the ring 3 was placed before inserting the ground reinforcing steel pipe into the ground. Since the ring acts as a fulcrum of the lever principle on the opposite side of the location, the ground reinforcing steel pipe can be easily separated.

Although the method of reinforcing the ground when the ring 3 is arranged in the groove portion 2 has been described, when the groove portion 2 is provided with the notch portion 6, the ring 3 can be attached arbitrarily. When the notch 6 is provided in the groove 2, when the striking D is applied to the ground reinforcing steel pipe, a tensile force acts on the portion of the notch 6 closest to the portion to which the striking D is applied, and the ground reinforcing steel pipe is provided. 10 separates. Further, when both the ring 3 and the notch 6 are provided in the groove 2, when the striking D is applied to the steel pipe for reinforcing the ground, the lever force of the ring 3 and the tensile force of the notch 6 act together. The ground reinforcing steel pipe 10 is separated.

As described above, the ground reinforcing steel pipe 10 can be easily separated by the ground reinforcing method of the present invention due to the action of leverage by the ring 3 or the action of tensile force by the notch 6 when hit. Is.

10 ... Steel pipe for ground reinforcement, 101-104 ... Steel pipe, 2 ... Groove, 3 ... Ring (ring-shaped member), 4 ... Connection, 5 ... Slit, 6 ...・ ・ Notch

Claims (10)

A steel pipe for reinforcing the ground that is inserted into the ground and injects a solidifying agent into the ground.
Grooves for cutting are provided along the circumferential direction at at least one position in the longitudinal direction.
A ring-shaped member having a width slightly narrower than the width of the groove and 70% or more of the width of the groove is arranged in the groove.
A steel pipe for ground reinforcement, wherein the rigidity of the ring-shaped member is equal to or higher than the rigidity of the material constituting the steel pipe body. The steel pipe for ground reinforcement according to claim 1.
The ring-shaped member is a steel pipe for reinforcing the ground, which is arranged in a range of 200 degrees or more and 360 degrees or less of the groove when the circumference of the groove is 360 degrees. The steel pipe for ground reinforcement according to claim 1.
The ring-shaped member is a steel pipe for reinforcing a ground, which has a circular, elliptical, or quadrangular cross-sectional shape. The steel pipe for ground reinforcement according to claim 1.
The ring-shaped member is a steel pipe for ground reinforcement, characterized in that the dimension of the groove portion in the depth direction is equal to or less than the depth of the groove portion. The steel pipe for ground reinforcement according to claim 1.
Consists of multiple steel pipes connected via a connection
A steel pipe for reinforcing a ground, characterized in that at least one of the plurality of steel pipes is provided with the groove portion and the ring-shaped member. The steel pipe for ground reinforcement according to claim 5.
A steel pipe for reinforcing a ground, characterized in that at least one of the connecting portions of the plurality of steel pipes is provided with the groove portion and the ring-shaped member. The steel pipe for ground reinforcement according to any one of claims 1 to 6.
The groove portion is a steel pipe for ground reinforcement, characterized in that the cross-sectional shape has a quadrangular shape, a V-shape, a U-shape, or a shape obtained by combining these. The steel pipe for ground reinforcement according to any one of claims 1 to 6.
The groove portion is a steel pipe for ground reinforcement, characterized in that a notch portion in the depth direction of the groove portion is formed at the bottom portion. It is a method of reinforcing the ground by inserting a steel pipe for reinforcing the ground into the ground and injecting a solidifying agent.
Including a step of cutting a part of the ground reinforcing steel pipe outside the ground after injecting the solidifying agent.
The ground reinforcing steel pipe has a groove for cutting along the circumferential direction.
Prior to the cutting step, the rigidity of the cutting groove is equal to or greater than the rigidity of the material constituting the steel pipe body, and the width is slightly narrower than the width of the groove and 70% of the width of the groove. The ground reinforcement method comprising the above-mentioned step of arranging the ring-shaped member. The ground reinforcement method according to claim 9.
The step of arranging the ring-shaped member is performed on a groove located at least rearward in the insertion direction of the ground reinforcing steel pipe before inserting the ground reinforcing steel pipe into the ground. Mountain reinforcement method.

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