JP2022094158A - Extended steel pipe, steel pipe for ground reinforcement, and construction method using the same - Google Patents

Abstract

To provide an extended steel pipe that a joining action of a steel pipe at a site is unnecessary or minimized, thereby significantly reducing a work time and the amount of the work in a ground reinforcement construction of a tunnel and the like.SOLUTION: Steel pipes 1A and 1B having different diameters are combined and an extended steel pipe in which one or more inner steel pipes having a smaller diameter can be nested inside an inner side of a steel pipe having the maximum diameter is made. The extended steel pipe includes a return prevention mechanism 30 inside thereof that locks the steel pipe at a withdrawal position when the steel pipe is withdrawn to be in an extended state.SELECTED DRAWING: Figure 2

Description

The present invention relates to steel pipes used for civil engineering, construction, steel towers, scaffolding, columns and other structures, and particularly to drawn steel pipes capable of combining a plurality of steel pipes into a long steel pipe.

Steel pipes are placed inside the building to support the structure of the building, as scaffolding to be installed around the building when building, maintaining, and inspecting the building, and also as a steel pipe for reinforcing the ground. It is widely used as. The length of the steel pipe required for such an application varies depending on the application, but for a large structure or the like, a long one exceeding 10 meters is also used. However, it is difficult to manufacture such a long steel pipe with high accuracy, that is, with a uniform thickness and without axial deformation. Therefore, in applications where long lengths are required, relatively short steel pipes, for example, about 3 meters, are usually joined together at the site where they are used.

Although the joining differs depending on the application, welding and screwing of steel pipes, joining using a joint member, and the like are performed (Patent Documents 1 and 2). For the work, the centering work is performed after bringing the steel pipes to be joined close to one laid steel pipe, and the joining work is performed. Such work is a heavy burden on the worker, even if the scaffolding is fairly unstable, the work is in bad weather, or there is mechanical support.

In the technique described in Patent Document 1, the workability at the time of screwing is improved by improving the structure of the screw. Further, in the technique described in Patent Document 2, the workability of centering is improved by using a special joint.

Japanese Unexamined Patent Publication No. 2020-105899 JP-A-2017-155469

In the techniques described in Patent Documents 1 and 2 described above, the burden of the joining work is reduced by devising the structure of the joining portion, but the joining work is still necessary, and the joining is still necessary. The work of positioning the other steel pipe with respect to the steel pipe to be made, and the work for centering and joining, although reduced, are indispensable.

It is an object of the present invention to eliminate the need for joining of steel pipes in the field, thereby significantly reducing the working time and the amount of working.

In order to solve the above problems, the present invention provides a drawn steel pipe in which steel pipes having different diameters are arranged in a nested manner. The steel pipe constituting the drawn steel pipe has a first tubular member that slides in the axial direction fitted on the outer periphery of the steel pipe located inside, and the end portion of the steel pipe located on the outer side on the outer peripheral surface of the first tubular member. Is fixed. The first tubular member is configured such that the axial movement is restricted by the second tubular member provided at the end of the inner steel pipe, and the inner steel pipe and the outer steel pipe do not separate from each other.

Further, the drawn steel pipe of the present invention has a return prevention mechanism that locks the reverse movement of the first tubular member by inserting a ring material between the end of the second tubular member and the first tubular member. It can be configured to be provided.

The ground reinforcing steel pipe of the present invention is a drawn steel pipe in which a plurality of steel pipes having different diameters are combined, and an inner steel pipe having a smaller diameter can be stored inside the steel pipe having a larger diameter. Preferably, the plurality of steel pipes are provided with a locking mechanism that prevents the two steel pipes from being separated from each other when one of the two radially adjacent steel pipes is slid with respect to the other. More preferably, the plurality of steel pipes are reversed at a position where the end of one steel pipe and the end of the other steel pipe overlap when one of two radially adjacent steel pipes is slid with respect to the other. It is equipped with a return prevention mechanism that locks the slide in the direction.

In the state before laying, the stretched steel pipe of the present invention is in a state where one or a plurality of inner steel pipes are nested inside the steel pipe having the maximum diameter, and is almost the same length as the steel pipe having the maximum diameter. However, in the state of using it, the outer or inner steel pipe is pulled out and lengthened. At this time, the first tubular member fitted to the inner steel pipe slides on the outer peripheral surface of the inner steel pipe together with the outer steel pipe to be lengthened. Since the movement of the first tubular member is restricted by the second tubular member, the outer steel pipe and the inner steel pipe do not come off.

Further, since the first tubular member is locked at the position where it abuts on the second tubular member by the return prevention mechanism, it becomes long in the application where the drawn steel pipe of the present invention is used in the vertical direction or the diagonal direction. The state does not return to the nested state before use, and a stable structure is maintained.

In the whole view which shows the embodiment of the drawn steel pipe of this invention, (A) shows the stored state, and (B) shows the extended state. FIG. 5 is a cross-sectional view showing a joint portion between steel pipes of the drawn steel pipe of the first embodiment. The figure which shows the main part of the joint part between steel pipes of the drawn steel pipe of Embodiment 1. FIG. The whole view which shows the embodiment of the steel pipe for ground reinforcement of this invention. It is a figure which shows the tip part of the steel pipe for ground reinforcement, (A) shows the case where the leading pipe is a steel pipe with the smallest diameter, and (B) shows the case where the leading pipe is a steel pipe with the largest diameter. The figure explaining the construction method using the steel pipe for ground reinforcement.

<Embodiment 1>
Hereinafter, embodiments of the drawn steel pipe of the present invention will be described with reference to the drawings. In the drawings, the dimensions of the steel pipe and its attached structures, the ratio of the dimensions, etc. are drawn for the sake of explanation, and are not interpreted as a scale of the dimensions of the stretched steel pipe or the structure of the present invention. ..

The drawn steel pipe of the present invention is a combination of a plurality of steel pipes, and in the following embodiment, a drawn steel pipe in which four steel pipes are combined will be described as an example. If the number of steel pipes is 2 or more, the number is not limited to 4, but the maximum diameter and the minimum diameter are selected to satisfy the allowable size and allowable strength according to the application.

The stretched steel pipe 1 shown in FIG. 1 is composed of four steel pipes 1A, 1B, 1C and 1D having different diameters, and steel pipes 1B, 1C and 1D having smaller diameters are sequentially placed inside the steel pipe 1A having the largest diameter. It has a structure that is slidably arranged in the. As shown in FIG. 1A, the drawn steel pipe 1 generally contains the other three steel pipes 1B to 1D inside the steel pipe 1A in the state before being laid, but at the time of laying, FIG. 1 As shown in (B), it is used in a state where it is stretched and lengthened to fix the joints of each steel pipe. Hereinafter, the former is referred to as a stored state, and the latter is referred to as an extended state. Further, in the following description, when explaining the matters common to the four steel pipes, the reference numerals are not distinguished and the steel pipe 10 is used.

The material and size of the steel pipe 10 differ depending on the intended use, but the stretched steel pipe of the present invention is used for structural reinforcement and ground reinforcement, and has strength to withstand it. For example, a steel pipe having a total length of about 3 m, a wall thickness of 3.5 mm to 4.5 mm, and an outer diameter of about 114 mm to about 76 mm can be used in combination. Specifically, it is preferable to use a combination of high tensile strength steel pipes such as STK400, STK490, and STK700.

Of the four steel pipes, a flange portion 15 having an outer diameter larger than the outer diameter of the steel pipe 10 is formed at the end of the steel pipe 10 (1A or 1D) which is the end in the extension structure. Also, this allows the inner steel pipe to be easily pulled out of the storage structure. The flange 15 can also function as a connecting portion with another structure (for example, a base or a beam of a structure).

The connecting portion between the steel pipe having a large diameter and the steel pipe located inside thereof is provided with a mechanism (locking mechanism and locking portion) for firmly connecting the two in the post-casting structure. This mechanism is common to the connecting portion between the steel pipe 1A and the steel pipe 1B, the connecting portion between the steel pipe 1B and the steel pipe 1C, and the connecting portion between the steel pipe 1C and the steel pipe 1D. The details of the mechanism of the connecting portion will be described. In the following description, the end of the steel pipe means the end on the connecting portion side between the steel pipe 1A and the steel pipe 1B unless otherwise specified.

As shown in FIGS. 2 and 3, a thread groove 11 is formed at the end of the inner steel pipe 1B, and a tubular member 21 (second tubular member) is screwed and fixed to the thread groove 11. ing. The outer diameter (D ₂₁ ) of the tubular member 21 is slightly smaller than the inner diameter (D _1A ) of the outer steel pipe 1A, and the steel pipe 1A can slide (slide) on the outer side thereof.

Further, a tubular member 22 (first tubular member) is slidably fitted on the outer periphery of the steel pipe 1B in the axial direction of the steel pipe 1B. The inner peripheral surface of the tubular member 22 is a smooth surface because it slides on the outer peripheral surface of the steel pipe 1B, but a threaded groove 23 is formed on the outer peripheral surface, and the outer steel pipe 1A is formed in the threaded groove 23. The end of the is screwed and fixed. The inner diameter (D ₂₂ ) of the tubular member 22 is smaller than the outer diameter (D ₂₁ ) of the tubular member 21, and when the tubular member 22 slides to the end of the steel pipe 1B, its end face comes into contact with the end face of the tubular member 21. , The movement is stopped. That is, the tubular member 21 and the tubular member 22 function as a locking mechanism, and prevent the steel pipe 1A fixed to the tubular member 22 from being pulled out from the steel pipe 1B. This position is the position where the steel pipe 1A is stretched to the maximum with respect to the steel pipe 1B.

As described above, this connecting portion is the same for the connecting portion between the steel pipe 1B and the steel pipe 1C and the connecting portion between the steel pipe 1C and the steel pipe 1D. ), The length is obtained by subtracting the “lengths of the tubular members 21 and 22” × 3 from the “total length of the steel pipe” × 4. For example, assuming that the total length of the steel pipe is 3.05 m and the length of the tubular member 21 is about 70 mm, a steel pipe having a total length of about 12 m can be obtained. Since both ends of the steel pipes other than the outermost steel pipe 1A and the innermost steel pipe 1D are connecting portions, the tubular member 21 is fixed to one end and the other end is connected to the inner side. The structure is connected to the tubular member 22 fitted to the steel pipe. It is not necessary to fit the tubular member 22 on the outer periphery of the steel pipe 1A, and it is not necessary to provide the tubular member 21 at one end of the steel pipe 1D.

As the material of the tubular member 21 and the tubular member 22, a material having a strength equal to or higher than that of the steel pipe can be used. Further, the length of the tubular member 21 and the tubular member 22 in the steel pipe axial direction may be such that the strength of the bond between the tubular member 21 and the steel pipe 1B and the bond between the tubular member 22 and the steel pipe 1A is maintained, in particular. Although not limited, it may be, for example, about 10 mm to 100 mm. By increasing the length of the tubular members 21 and 22, the strength of the connecting portion can be increased. In the above example, both are connected by screwing, but for example, the tubular member 21 can be integrally formed with the steel pipe 1B, or may be fixed by welding or the like. By screwing the tubular member 22, it becomes possible to easily manufacture the drawn steel pipe in the manufacturing of the drawn steel pipe described later.

Next, a means (return prevention mechanism) for fixing the stretched steel pipe of the present embodiment at the position where the steel pipe 1A and the steel pipe 1B are stretched to the maximum will be described. If the force to return the extended steel pipe to the storage structure is not applied in the place or situation where the drawn steel pipe is placed, the return prevention mechanism is not essential, but the return prevention mechanism should be provided inside the connecting part. As a result, a strong connecting structure can be obtained without using means for fixing the connecting portion from the outside, such as screws, clamps, and welding.

Hereinafter, the structure of the return prevention mechanism of the drawn steel pipe of the present embodiment will be described with reference to FIG. The return prevention mechanism of the present embodiment is provided on the inner peripheral surface of the ring member 30 arranged on the outer periphery of the connecting portion of the steel pipe 1B and the tubular member 22 to which the steel pipe 1A is fixed, and is a recess that engages with the ring member 30. 31 and.

The ring member 30 is formed of a rigid material such as a leaf spring and has a substantially rectangular cross section in a ring shape. As shown in FIG. 3, the ring member 30 has a thread groove 11 of an inner steel pipe 1B. It is fitted in the recess 12 between the outer circumference of the steel pipe and the outer circumference of the steel pipe in which the thread groove is not cut. Both ends of the ring member 30 are not connected and are arranged so as to surround the outer circumference of the steel pipe 1B, and the length thereof is slightly shorter than the outer circumference of the steel pipe 1B, but is preferably 70% or more of the outer circumference.

As shown in FIG. 3, the cross section of the ring member 30 has a substantially quadrangular shape, and is fitted to the steel pipe 1B in a state of being slightly floating from the recess 12 of the steel pipe 1B. On the other hand, in the tubular member 22, a concave portion 31 is formed in an annular shape on the inner peripheral surface near the end portion in contact with the tubular member 21 so that the ring member 30 can be inserted. The distance from the end face of the tubular member 22 to the end of the recess 31 is substantially equal to the distance from the end face of the tubular member 21 to the recess 12 of the steel pipe 1B.

In such a structure, as shown in FIG. 3A, when the steel pipe 1A before connection is slid toward the connection portion together with the tubular member 22, the ring member 30 is reduced to the inner diameter of the steel pipe 1A. When the tubular member 22 further slides and comes into contact with the end face of the tubular member 21, the recess 31 is located directly above the ring member 30, thereby expanding the diameter of the ring member 30. Then, it spreads to the recess 31 of the steel pipe 1A and fits. In this state, the ring member 30 engages the recess 31 with the recess 12. Therefore, even if a force acts in the direction away from the connecting portion (returning direction), the movement of the tubular member 22 is locked by the engagement between the ring member 30 and the recess 31. That is, the steel pipe 1A fixed to the tubular member 22 is locked in the connected state.

The drawn steel pipe of this embodiment can be assembled by the following method. First, a plurality of steel pipes having different diameters constituting the drawn steel pipe are prepared, and for all the steel pipes except the steel pipe having the maximum diameter, a thread groove 11 having a predetermined length and a recess for a ring member adjacent to the thread groove 11 on the outer circumference of one end thereof are prepared. 12 is formed (step 1). Further, for all steel pipes except the minimum diameter steel pipe, a thread groove 11 is formed on the inner peripheral surface of the other end (the end opposite to the end on which the thread groove is formed) (step 2).

On the other hand, a tubular member 21 screwed into the thread groove 11 of each steel pipe and a tubular member 22 having an inner diameter slightly larger than the outer diameter of each steel pipe are prepared, and a thread groove 23 is formed on the outer peripheral surface of the tubular member 22. A recess 31 into which the ring member fits is formed (step 3).

Next, after fitting the tubular member 22 produced in step 3 to the outside of the steel pipe, the tubular member 21 is screwed and fixed in the thread groove 11 of the steel pipe (step 4). For the steel pipe having the smallest diameter, the flange 15 is fixed to the end opposite to the end where the thread groove 11 is formed, if necessary (step 5). The flange 15 may be fixed at any stage of steps 1 to 4.

Finally, the end portion of the steel pipe having an outer diameter slightly larger than that of the steel pipe (the end having the thread groove 13 formed on the inner peripheral surface) is screwed into the tubular member 22 fitted to the outer periphery of the minimum diameter steel pipe. (Step 6). By performing this step 6 in ascending order of diameter, the connection of all the steel pipes constituting the drawn steel pipe is completed.

The above manufacturing method is an example of the drawn steel pipe of the present invention, and does not limit the drawn steel pipe of the present invention.

As described above, the drawn steel pipe of the present embodiment is a drawn steel pipe having a novel structure capable of changing a plurality of steel pipes having different diameters from a storage structure to an extension structure, and the storage structure is changed to an extension structure at the laying place. Therefore, the labor and labor of laying while joining a plurality of steel pipes can be greatly reduced. Further, since the stretched steel pipe of the present embodiment has a structure in which the steel pipe and the tubular member are tripled, the joint portion is stronger and more stable than the joint portion of the steel pipe by normal screwing. Structures can be provided. Further, the stretched steel pipe of the present embodiment is provided with a lock portion, so that it is not necessary to use another fixing means for fixing the movement of the steel pipe in the sliding direction or to apply the same at the time of laying, and it is possible to perform strong fixing.

Although the steel pipe has a circular cross section in the drawings, the drawn steel pipe of the present invention can be similarly applied to a shape other than the circular cross section, for example, a square or polygonal steel pipe.

<Embodiment 2>
In the first embodiment, the drawn steel pipe used for the structure has been described, but in the present embodiment, an embodiment in which the drawn steel pipe of the present invention is used as a ground reinforcing steel pipe will be described.

When a stretched steel pipe is used for a structure, it is conceivable to use it mainly with the axial direction of the steel pipe being vertical or horizontal. It is used to reinforce the ground by driving into. The ground reinforcement that is driven diagonally from the top is called the pre-receiver, and the reinforcement that is driven horizontally from the mirror surface is called the mirror work. The drawn steel pipe of this embodiment can be applied to any of them.

The main structure of the ground reinforcing steel pipe 100 is the same as that of the drawn steel pipe of the first embodiment, and for example, as shown in FIG. 4, it is composed of a combination of four steel pipes 1A to 1D having different diameters. The four steel pipes are called a leading pipe, an intermediate pipe (two), and a terminal pipe in this order, with the side driven into the ground as the head. FIG. 4 shows a case where the steel pipe 1A having the maximum diameter is the leading pipe as an example. The structure for connecting these steel pipes is the same as that of the first embodiment, and the details are omitted, but the tubular member 21 is screwed to the end of the inner steel pipe, and the tubular member 22 is attached to the outer periphery of the inner steel pipe. It is slidably fitted and the outer steel pipe is screwed and fixed to the outer periphery of the tubular member 22, and the ring member 30 is arranged on the inner steel pipe to which the tubular member 21 is screwed to form a lock portion. , And so on.

Further, when used as a steel pipe for reinforcing the ground, a discharge hole or a slit for discharging the fixing material to be injected after the steel pipe is driven into the ground may be formed. As for the shapes and positions of the discharge holes and slits, the same method as known methods can be adopted, and detailed description thereof will be omitted here.

It is possible to use the same material and size of the steel pipe as known steel pipes, but it is particularly preferable to use a high yield strength steel pipe having a thin wall thickness. Further, the material and size may be changed depending on whether it is a leading pipe, an intermediate pipe, or a terminal pipe. Further, as a mode of use, there may be a mode in which steel pipes having a smaller diameter in order from the head pipe are connected, and a mode in which steel pipes having a larger diameter in order from the head pipe are connected as shown in FIG. Table 1 shows an example of a four-piece ground reinforcing steel pipe when the casting length L is 12.5 m.

Example 1 is an example in which the head pipe is made of a steel pipe having the maximum diameter, and Example 2 is an example in which the head pipe is made of a steel pipe having the smallest diameter. Example 3 is an example in which only the terminal tube has a small diameter. Since the terminal pipe is finally cut off from the ground to the outside in the tunnel construction, a pipe thinner than the head pipe is used to facilitate the work.

In either case, in the case of the ground reinforcing steel pipe, a flange 15 is provided at the tip of the steel pipe serving as the terminal pipe, and the flange 15 is used as a rock drill centralizer 82 in the driving process described later. The steel pipe can be pulled out in sequence by hooking it on the pipe and hitting and placing it. In addition, a tool (bit) for excavating the ground is rotatably attached to the tip of the steel pipe, which is the leading pipe.

The bit 50 is a tool in which a cemented carbide tip for placing is formed and the bit 50 is rotated by a drive source to excavate a ground. An adapter 60 is fitted to the tip of a rod 70 connected to the drive source. There is. Conventionally, the rod is used properly according to the size of the steel pipe, but in the present embodiment, the rod 70 can be shared by inserting the inner guide 55 into the opening of the bit 50.

That is, in this embodiment, the bit 50 and the rod 70 are connected by the following structure. The front surface of the bit is open, and the inner peripheral surface thereof is formed with an uneven shape into which the inner guide 55 or the tip of the rod is fitted. The inner guide 55 is an annular member, and an uneven shape that fits with the uneven shape of the bit is formed on the outer peripheral surface thereof. Further, the inner peripheral surface of the inner guide 55 is formed with an uneven shape that fits with the uneven shape of the outer peripheral surface of the adapter 60. The outer peripheral surface of the adapter 60 fitted to the tip of the rod is formed with an uneven shape that engages with the uneven shape of the inner peripheral surface of the inner guide 55 or the uneven shape of the inner peripheral surface of the bit 50.

With such a configuration, when the leading pipe is a steel pipe 1A having the maximum diameter, as shown in FIG. 5 (B), the maximum diameter is attached to the bit 50 fixed to the tip of the steel pipe using the inner guide 55 and the adapter 60. Install the steel pipe bit. Further, even if the leading pipe is a steel pipe having the smallest diameter, as shown in FIG. 5 (A), the rod for the steel pipe having the maximum diameter can be used as it is, and it is fitted to the bid fixed to the leading end of the leading pipe as in the conventional case. Can be made to. By using the inner guide in this way, even if the steel pipes and rods of different sizes are combined, the two can be detachably fitted to each other.

In either case, by rotating the rod 70 with the adapter 60 at the tip of the rod 70 inserted into the inner guide 55 (bit 50 when the inner guide is not used), both uneven shapes are fitted to the rod. 70 is fixed to the bid 50. When the rod 70 is rotated in the reverse direction (counterclockwise rotation), the fitted state of the uneven shape is released, and the rod 70 can be removed from the bit 50. At the time of excavation, the rod 70 is inserted from the end of the terminal pipe of the steel pipe and attached to the bit 50 as described above. After drilling a predetermined length, the bit 50 and the inner guide 55 are left on the ground together with the reinforcing steel pipe, but the adapter 60 and the rod 70 are removed from the bit 50 and pulled out to the outside.

Next, an example of a construction method (casting method) using the ground reinforcing steel pipe having the above-mentioned configuration will be described. Here, a case of a drawn steel pipe composed of four steel pipes having a leading pipe as the maximum diameter will be described with reference to FIG.

First, as a preparatory step, a drawn steel pipe 100 having a bit 50 fixed to the tip of the leading pipe is prepared. This stretched steel pipe is set in the guide shell 81 installed near the casting location in the stored state. The guide shell 81 is a long device equipped with a drifter (bit drive source) 80, and the guide shell 81 has a pair of steel pipe receiving jigs (centralizer / centralizer /) in order to align the core of the steel pipe with the excavation direction. A sub-centralizer) 82 is provided, and a drifter 80 is mounted behind the sub-centralizer) 82. The rod 70 is connected to the drifter 80, the rod 70 is inserted into the drawn steel pipe 100, and the rod 70 is attached to the bit 50 fixed to the leading pipe. It is possible to use a rod 70 having a length similar to that of the casting length, but usually, two or three rods are connected and used. In this case, each rod is about twice as large as the steel pipe constituting the drawn steel pipe.

Next, the guide shell 81 is set so that the bit 50 comes into contact with the target casting position, and the drifter 80 is driven to start excavation by the bit 50 (FIG. 6: Start of casting). The excavation progresses with the rotation of the bit 50, and the rock fragments and soil generated by the excavation are discharged from the inside of the steel pipe. At the same time, the bit 50 and the leading pipe (1A) advance into the ground. At this time, only the leading pipe is pulled out from the drawn steel pipe 100, and the other steel pipes stay at the position of the steel pipe receiving jig 82 in the stored state (FIG. 6: during casting).

The state in which the leading tube is pulled out to the maximum, that is, the tubular member 22 to which the leading tube is fixed abuts on the tubular member 21 of the intermediate tube inside, and the intermediate tube is formed in the recess formed on the inner peripheral surface of the leading tube. When the ring member 30 is fitted, the leading pipe and the intermediate pipe inside the leading pipe are fixed. Here, the second rod is connected to the rear end of the first rod, and the excavation by the bit is continued.

As the excavation progresses, the second intermediate pipe is also pulled out from the inner steel pipe (third steel pipe) and advances into the ground as the leading pipe moves. Even after the second intermediate pipe is pulled out to the maximum and the second intermediate pipe is fixed to the third intermediate pipe, by continuing excavation, the third intermediate pipe also advances to the ground. do. In these series of pull-out operations (steel pipe slides), the flange 15 of the terminal pipe is caught by the steel pipe receiving jig 82, so that a smooth continuous pull-out operation is performed with this as a fulcrum.

After casting, rotating the rod in the reverse direction to remove it from the bit and pulling it out from the steel pipe, and injecting the fixing material for reinforcement from the end of the end pipe are the same as the general casting method, which will be explained here. Is omitted.

As described above, according to the construction method of ground reinforcement using the drawn steel pipe of the present invention, the steel pipe connection work which was indispensable in the past, and the heavy steel pipe necessary for that purpose are sequentially installed in the guide shell 81. It is possible to eliminate various work that imposes a heavy burden on the operator, such as work to be performed, centering work for connection, and screwdriver work. Moreover, since the casting work can be performed continuously, the construction time can be significantly shortened. For example, in the past, it took about 10 minutes to connect steel pipes, but by just connecting rods, it can be shortened to about 3 minutes, and the construction time for one cross section is 25 pieces. If so, it will be shortened by about 2.5 hours and the productivity will be greatly improved.

Further, since the steel pipe for reinforcing the ground of the present invention is a combination of steel pipes having different diameters in the axial direction, higher adhesive force to the ground is expected as compared with the steel pipe having a single diameter.

In the above description, a stretched steel pipe composed of four steel pipes is used, but it is also possible to use a stretched steel pipe composed of two to three steel pipes, and one ordinary steel pipe is used depending on the casting length. Alternatively, it is possible to connect and use a plurality of pipes. For example, after driving one or two ordinary steel pipes, the drawn steel pipes of the present invention are connected and continuously stretched and placed as described above, or after the drawn steel pipes of the present invention are placed, the ordinary steel pipes are placed. It may be connected and placed. In that case, a structure that can be connected to a normal steel pipe, for example, a thread groove, may be formed in the leading pipe or the terminal pipe of the drawn steel pipe. Such a construction method is also included in the construction method using the drawn steel pipe of the present invention.

1: Stretched steel pipe, 1A to 1D: Steel pipe, 11: Thread groove, 12: Recess, 15: Flange, 21: Tubular member (second tubular member), 22: Tubular member (first tubular member), 23: Thread groove, 30: Ring member (return prevention mechanism), 31: Recess, 100: Steel pipe for ground reinforcement, 50: Bit, 55: Inner guide, 60: Adapter, 70: Rod, 80: Drifter, 81: Guide shell , 82: Steel pipe receiving jig (centralizer / sub-centralizer).

Claims (16)

A stretched steel pipe in which a plurality of steel pipes having different diameters are combined and one or more inner steel pipes having a smaller diameter can be nested inside the steel pipe having the maximum diameter.
In the inner steel pipe, a first tubular member slidable along the axial direction of the steel pipe is fitted to the outer peripheral surface, and a second tubular member is fixed to the outer peripheral surface of the end portion.
The outer diameter of the second tubular member is larger than the inner diameter of the first tubular member and smaller than the inner diameter of the steel pipe adjacent to the outside of the inner steel pipe.
The adjacent steel pipe is a stretched steel pipe characterized in that it is fixed to the outer peripheral surface of the first tubular member. The stretched steel pipe according to claim 1.
A stretched steel pipe comprising a return prevention mechanism that locks the movement of the adjacent steel pipe in the sliding direction between the outer peripheral surface of the inner steel pipe and the second tubular member. The stretched steel pipe according to claim 2.
The return prevention mechanism is a ring member that fits into a recess formed at the boundary between the outer peripheral surface of the inner steel pipe and the second tubular member, and the ring member is engaged with the inner peripheral surface of the adjacent steel pipe. A drawn steel pipe characterized in that a matching recess is formed. The stretched steel pipe according to claim 1.
The adjacent steel pipe is a drawn steel pipe having one end fixed to the outer peripheral surface of the first tubular member by screwing. A steel pipe for ground reinforcement, which comprises the stretched steel pipe according to claims 2 to 4. A steel pipe for ground reinforcement that combines two or more steel pipes including a leading pipe and a terminal pipe.
It consists of a stretched steel pipe in which a plurality of steel pipes having different diameters are combined and an inner steel pipe having a smaller diameter is slidably arranged inside the steel pipe having a larger diameter. A steel pipe for ground reinforcement characterized by having a structure that pulls out the steel pipe and changes it to an extended state. The steel pipe for reinforcing the ground according to claim 6.
The plurality of steel pipes are provided with a stop mechanism for preventing the two steel pipes from separating from each other when one of the two pipes adjacent in the radial direction is slid with respect to the other. The steel pipe for reinforcing the ground according to claim 6.
When one of two radially adjacent steel pipes is slid with respect to the other, the plurality of steel pipes slide in the opposite direction at a position where the end of one steel pipe and the end of the other steel pipe overlap. A steel pipe for reinforcing the ground, which is characterized by having a lock-back prevention mechanism. The steel pipe for reinforcing the ground according to claim 6.
The leading pipe is a steel pipe for ground reinforcement, characterized in that it is a steel pipe having the maximum diameter. The steel pipe for reinforcing the ground according to claim 6.
The leading pipe is a steel pipe for ground reinforcement, characterized in that it is a steel pipe having the smallest diameter. The steel pipe for reinforcing the ground according to claim 6.
A steel pipe for reinforcing a ground, which is composed of a plurality of steel pipes and has an outer diameter of a minimum of 60.5 mm to a maximum of 139.8 mm. It is a construction method that reinforces the tunnel peripheral wall using steel pipes.
A construction method comprising using the ground reinforcing steel pipe according to claim 6 as the steel pipe. The construction method according to claim 12.
In a state where a plurality of steel pipes for reinforcing the ground are housed in a nested manner, a bit for driving is fixed to the end of the leading pipe, and a rod for supplying power to the bit is used for reinforcing the ground. A preparatory step of fitting the bit through the inner guide so as to pass through the inside of the steel pipe.
The first step of supplying power to the bit, driving while rotating the bit, and pulling out the leading pipe from the stored state to enter the ground, and further driving are continued, and the leading pipe is continued. A construction method including a second step of sequentially pulling out intermediate pipes and terminal pipes connected to the ground and allowing them to enter the ground, and the first step to the second step are continuously performed. The construction method according to claim 13.
A construction method further comprising a step of pulling out the rod from the steel pipe to the outside at the end of casting, in which the rod is detachably engaged with the inner guide. The construction method according to claim 13.
The construction method is characterized in that the terminal pipe has a flange for fixing the terminal pipe to the rock drill, and the flange is hooked on the rock drill to determine the final position of driving. The construction method according to claim 13.
The rod is a rod for steel pipes having the maximum diameter.
The construction method is characterized in that the preparation step includes a step of connecting an inner guide and an adapter between a bit fixed to the tip tube and the rod.

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