JP6359320B2 - Casing segment connection structure in the micropile method - Google Patents

Description

The present invention, continuous fine granulated about the casing segments in the micro pile method.

The micropile construction method is a generic name for small-sized cast-in-place piles with a diameter of 300 mm or less, for reasons such as being sufficient with compact construction equipment, being able to be constructed in a narrow space, and being able to be constructed without stopping the functions of existing structures. It is used for various purposes including seismic reinforcement of existing structures, ground reinforcement, and stabilization of slopes.
In the micropile method, first, the first rod having a drilling drill attached to the tip is inserted into the first casing segment whose outer periphery is the outer drilling cutter. A step of drilling while rotating the casing segment and the rod and injecting water is performed.
Then, at each predetermined depth, the next casing segment is detachably connected to the end of the casing segment and added, and the next rod is detachably connected to the end of the rod and added to the casing segment. A process of drilling while rotating the rod and injecting water is performed.

Next, when the drilled hole reaches a predetermined depth, a step of pulling out the drill with the rod from the inside of the casing segment is performed.
Next, if necessary, a reinforcing material is disposed inside the casing over the entire length of the casing.
Next, a process of pulling out the casing segment by a predetermined length while filling the grout material is performed.
In such a micropile method, the casing segments are conventionally connected by using a hollow cylindrical casing joint having an outer diameter larger than the outer diameter of the casing segment.
That is, the casing segments are connected by screwing the internal threads of the inner peripheral surfaces at both ends in the longitudinal direction of the casing joint into the external threads of the outer peripheral surfaces of adjacent casing segments.

Patent No. 4010383

Therefore, in the conventional micropile construction method, at the time of drilling, the casing joint protruding from the outer peripheral surface of the casing segment at the connecting portion of the casing segment becomes a resistance, which is disadvantageous in increasing the drilling efficiency.
Also, when pulling out the casing segment after drilling, the casing joint that protrudes from the outer peripheral surface of the casing segment at the connecting portion of the casing segment interferes with the hole wall surface, and the desired hole is obtained because the hole wall surface is destroyed. There are disadvantages in the above, and because the casing joint interferes with the hole wall surface, there is a disadvantage in increasing the drawing efficiency of the casing segment.

Specifically, the length of the casing segment is 1.5 to 3 m. Therefore, for example, in order to drill a depth of 54 m, even if a casing segment having a length of 3 m is used, 18 casing segments are required, and 17 casing joints are required.
Therefore, since the number of casing joints increases as drilling occurs, the resistance of the casing joints occurs at the maximum of 17 locations during drilling, and when the casing segment is pulled out, the casing joints interfere with the drilling wall surface. As a result, a maximum of 17 locations occur and a casing joint resistance occurs at a maximum of 17 locations, and some improvement has been desired.

The present invention has been devised in view of the above circumstances, and an object of the present invention is to increase the efficiency of drilling by the casing segment and to increase the extraction efficiency of the casing segment in the micropile method. to provide a continuous fine granulation of the casing segments in the micro pile method.

In order to achieve the above object, the invention according to claim 1 is a connecting structure of casing segments in the micropile method, wherein a female thread is formed on the inner peripheral surface of the longitudinal end portion of the casing segment, and the outer diameter is the casing. A hollow cylindrical casing joint having an outer diameter of the segment or less is provided, and a drill insertion hole having an inner diameter larger than the diameter of the drilling drill at the tip of the rod inserted into the casing segment passes through the casing joint. A male screw that can be screwed to the female screw is formed on the outer peripheral surface of the casing joint, and an end portion in a longitudinal direction of an adjacent casing segment is screwed into the female screw by the casing joint. removably coupled, said casing joint, a male screw portion to which the male screw is formed, the length of the external thread portion In the state in which the end portions in the longitudinal direction of adjacent casing segments are connected by the casing joint by the male screw being screwed to the female screw. The portion covers the female screw exposed inside the casing segment .
The invention according to claim 2 is a casing segment connection structure in the micropile method, wherein an internal thread is formed on the inner peripheral surface of the longitudinal end portion of the casing segment, and the outer diameter is equal to or smaller than the outer diameter of the casing segment. A hollow cylindrical casing joint is provided, and a drill insertion hole having an inner diameter larger than the diameter of the drilling drill at the tip of the rod inserted into the casing segment is formed through the casing joint. A male screw that can be screwed to the female screw is formed on the outer peripheral surface of the joint, and the end portions of adjacent casing segments in the longitudinal direction are detachably connected by the casing joint by screwing the male screw to the female screw. The longitudinal end of the adjacent casing segment on the inner peripheral surface of the longitudinal end of the casing segment. The drill is covered with the female screw exposed to the inside of the casing segment in contact with the longitudinal end of the casing joint in a state where the male screw is screwed to the female screw and connected by the casing joint. A cylindrical stopper member in which a hole having an inner diameter larger than the inner diameter of the insertion hole is formed is attached .
According to a third aspect of the present invention, the male screw is formed at both ends in the longitudinal direction on the outer peripheral surface of the casing joint, and the outer diameter is between the male screws at both ends in the longitudinal direction on the outer peripheral surface of the casing joint. Is formed with a flange that is larger than the outer diameter of the male screw and smaller than the outer diameter of the casing segment.

According to the present invention, since the inner peripheral surfaces of the end portions of the casing segment are connected by the casing joint inserted into the casing segment, there is no casing joint protruding from the outer peripheral surface of the casing segment as in the prior art. This is advantageous in increasing the drilling efficiency and the casing segment drawing efficiency.
Further , according to the present invention, since the male screw of the casing joint is screwed into the female screw on the inner peripheral surface of the end portion of the casing segment, the end portions of the casing segment can be reliably connected with a simple configuration.
In addition, according to the present invention, the end portions of the casing segments can be reliably connected with a simple configuration, which is advantageous in increasing the drilling efficiency and the casing segment drawing efficiency in the micropile method.
Further , according to the invention of the present invention, the flange can be gripped by a tool, which is advantageous in increasing the efficiency of the work of adding and removing the casing segment.
In addition, according to the present invention, it is possible to prevent the grout from entering the female screw at the end of the casing segment, which is advantageous in increasing the efficiency of the adding and removing work of the casing segment.

(A)-(G) are explanatory drawings of a micropile construction method. It is explanatory drawing of the outer side drilling cutter of the 1st casing segment front-end | tip, and the drilling drill of the front-end | tip of a 1st rod. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the connection structure of the casing segment of 1st Embodiment, (A) is explanatory drawing of the edge part of an adjacent casing segment, and a casing coupling, (B) is the casing coupling between the edge parts of an adjacent casing segment. It is explanatory drawing connected by. FIG. 6A is an explanatory diagram of a casing segment connection structure according to a second embodiment, and FIG. 6A is an explanatory diagram of an end portion of an adjacent casing segment and a casing joint, and FIG. It is explanatory drawing connected by. FIG. 7A is an explanatory diagram of a casing segment connection structure according to a third embodiment, and FIG. 9A is an explanatory diagram of an end portion of an adjacent casing segment and a casing joint, and FIG. It is explanatory drawing connected by. FIG. 4A is an explanatory diagram of a casing segment connection structure according to a fourth embodiment, and FIG. 4A is an explanatory diagram of an end portion of an adjacent casing segment and a casing joint, and FIG. It is explanatory drawing connected by. (A) is explanatory drawing of the edge part of an adjacent casing segment, and a casing coupling, (B) is the casing coupling between the edge parts of an adjacent casing segment. It is explanatory drawing connected by.

  Hereinafter, an embodiment of a method for adding casing segments in a micropile construction method according to the present invention will be described together with a first embodiment of a connecting structure of casing segments with reference to the accompanying drawings.

As shown in FIG. 1 (A) and FIG. 2, the inside of the first elongated hollow cylindrical steel casing segment 14 whose outer peripheral portion is the outer drilling cutter 12 when the micropile method is applied. Then, the first rod 18 having the drilling drill 16 attached to the tip is inserted, and the casing segment 14 and the rod 18 are rotated, and water is injected, and the outer drilling cutter 12 and the drilling are performed. A step of drilling the hole 20 with the hole drill 16 is performed.
Then, as shown in FIGS. 1B and 1C, every time the hole 20 reaches a predetermined depth, the following elongated hollow cylindrical steel casing segment 14 can be attached to and detached from the end of the casing segment 14. And the next rod 18 is detachably connected to the end of the rod 18 to add it, rotate the casing segment 14 and the rod 18, and inject water into the outer hole cutter. The process of drilling the hole 20 with the drill 12 and the drill 16 is performed.

In the present embodiment, as shown in FIGS. 3A and 3B, a drill insertion hole having a size in which the connection of the casing segment 14 is inserted into the casing segment 14 and allows the drilling drill 16 to move. The hollow cylindrical casing joint 22 through which 22A is formed is used, and the inner peripheral surfaces of the end portions of the casing segment 14 are detachably coupled to each other.
Casing C is constituted by connecting a plurality of casing segments 14.
As shown in FIG. 1C, when the drilled hole 20 passes through the soft layer 24 and reaches a predetermined depth of the load support layer 26, the drill 18 and the rod 18 are inserted into the casing C. The process of drawing from is performed.
Next, a reinforcing material such as a reinforcing bar is disposed inside the casing C over the entire length of the casing C as necessary.

Next, as shown in FIG. 1D, the grout material G is filled into the casing C using a tremy tube (not shown).
As the grout material G, cement milk, mortar material, or a concrete material mixed with a small diameter aggregate can be used.
Next, as shown in FIG. 1E, a step of pulling out the casing C is performed while the grout material G is pressurized and injected into the casing C.
It is desirable that the grouting material G be pressed at such a pressure that the grouting material G comes into close contact with the wall surface of the drilled hole 20 and the joining state between the grouting material G and the ground becomes strong.
When the upper end of the lower casing segment 14 is positioned on the ground, the lower casing segment 14 is non-rotatably gripped and the upper casing segment 14 is pulled out. Is operated by rotating and removing the upper casing segment 14 with respect to the lower casing segment 14. In addition, when removing the upper casing segment 14, the casing coupling 22 is also removed.
A plurality of casing segments 14 positioned above are removed together with the casing joint 22, and the lower end of the first casing segment 14 positioned at the lowest position is the uppermost portion of the load support layer 26 as shown in FIG. When it approaches, the extraction of the casing C is completed.

Next, as shown in FIG. 1 (F), a step of pushing the casing C back into the grout material G filled with the grout material G by a predetermined amount is performed, and a portion surrounded by the casing C and the casing A portion having an intermediate structure is created between the portion not surrounded by C.
And the pile body 30 which has 30 A of ground junction parts by the grout material G is obtained because the grout material G is hardened | cured.
Next, as shown in FIG. 1 (G), a steel bearing plate 32 is joined to the upper end of the casing C by welding to form a connection structure for connecting the pile head of the pile body 30 to the structure. Is done.

The connection structure of the casing segment 14 will be described in more detail. As shown in FIGS. 3A and 3B, a female thread 1402 is formed on the inner peripheral surface of the end of the casing segment 14 in the longitudinal direction.
That is, the first casing segment 14 whose outer peripheral portion at the front end in the longitudinal direction is the outer drilling cutter 12 has an internal thread on the inner peripheral surface of the end of the casing segment 14 positioned opposite to the outer drilling cutter 12. 1402 is formed. In the second and subsequent casing segments 14, female threads 1402 are formed on the inner peripheral surfaces at both ends in the longitudinal direction of the casing segment 14.

The casing joint 22 for connecting the casing segments 14 has a hollow cylindrical shape, and has an outer diameter equal to or smaller than the outer diameter of the casing segment 14 and a drill insertion hole 22A having a size allowing the drilling drill 16 to move inside. It is formed through.
A male screw 2202 that can be screwed into the female screw 1402 of the casing segment 14 is formed on the outer peripheral surface of the casing joint 22 over the entire length in the longitudinal direction of the casing joint 22.
The end portions of adjacent casing segments 14 in the longitudinal direction are simply and reliably connected by the casing joint 22 by the male screw 2202 being screwed into the female screw 1402.

In the present embodiment, since the inner peripheral surfaces of the end portions of the casing segment 14 are connected by the casing joint 22, the casing joint 22 is inserted into the casing segment 14 while the casing segment 14 is connected. Become.
After drilling, the drill 16 is pulled with the rod 18 so that the drill 16 has an outer diameter that can pass through the drill insertion hole 22A of the casing joint 22 located inside the casing segment 14. Is used.
That is, conventionally, since the end portions of the casing segment 14 are connected by using the casing joint 22 that is not located inside the casing segment 14 but located on the outer peripheral surface of the casing segment 14, the hole drill 16 is used as the casing segment 14. The thing of the outer diameter which can move the inside of 14 is used.
On the other hand, in the present embodiment, the drilling drill 16 must be dimensioned so that it can pass through the drill insertion hole 22A of the casing joint 22 arranged inside the casing segment 14, so that a conventionally used drilling drill is used. Compared to 16, a drilling drill 16 having a smaller outer diameter is used.

Theoretically, in the conventional micropile construction method, the inner peripheral surface of an annular recess drilled by the outer drilling cutter 12 and the inner peripheral surface of a cylindrical recess drilled by the drill 16 In the meantime, an annular wall corresponding to the thickness of the casing segment 14 remains. The annular wall portion is considered to be collapsed by vibration during drilling or by contact of the side portion of the outer drilling cutter 12 or the side portion of the drilling drill 16. A hole having an inner diameter corresponding to the outer diameter is smoothly drilled.
On the other hand, in the micropile method of the present embodiment, the inner peripheral surface of the annular recess that is drilled by the outer drilling cutter 12 and the inner periphery of the cylindrical recess that is drilled by the drilling drill 16. Between the surfaces, an annular wall portion having a thickness obtained by adding the thickness of the casing segment 14 and the thickness of the casing joint 22 remains. It is considered that this annular wall portion is also collapsed by vibration during drilling or by contact of the side portion of the outer drilling cutter 12 or the side portion of the drilling drill 16 as in the conventional case. The hole 20 having an inner diameter corresponding to the outer diameter of the hole cutter 12 is smoothly cut.
Therefore, in this embodiment, although the drilling drill 16 having a smaller outer diameter than the conventional one is used, the inner diameter hole corresponding to the outer diameter of the outer drilling cutter 12 is smoothly cut as in the conventional case. To be perforated.

According to the present embodiment, since the inner peripheral surfaces of the end portions of the casing segment 14 are connected by the casing joint 22 inserted into the casing segment 14, the outer peripheral surface of the casing segment 14 is conventionally used. The protruding casing joint disappears. Therefore, at the time of drilling, the problem that the casing joint becomes a resistance at the connecting portion of the casing segment 14 is eliminated, which is advantageous in increasing the drilling efficiency.
Similarly, when the casing segment 14 is pulled out after drilling, since there is no casing joint protruding from the outer peripheral surface of the casing segment 14, the casing joint interferes with the wall surface of the hole 20 in which the hole has been drilled and breaks down the wall surface. In addition, the problem that the casing joint interferes with the wall surface of the hole 20 at the time of pulling out and the resistance is eliminated is advantageous in increasing the pulling efficiency of the casing segment 14.
Further, since the male screw 2202 of the casing joint 22 is screwed into the female screw 1402 on the inner peripheral surface of the end portion of the casing segment 14, the ends of the casing segment 14 can be connected to each other with a simple configuration using the casing joint 22. It can be connected reliably.

Specifically, for example, in order to drill a depth of 54 m, even if a casing segment 14 having a length of 3 m is used, 18 casing segments 14 are required, and 17 casing joints 22 are required. Become.
Accordingly, since the number of casing joints 22 increases as the holes are drilled, the conventional problem that the resistance of the casing joint 22 has occurred at the maximum of 17 places at the time of drilling can be solved, and the casing segment 14 is pulled out. Also in this case, the conventional problems that the casing joint 22 interferes with the hole wall surface at 17 places at the maximum and the resistance of the casing joint 22 occurs at the 17 places at the maximum can be solved.
That is, it is advantageous to increase the drilling efficiency by the outer drilling cutter 12 and the drill 16, and is advantageous to increase the extraction efficiency of the casing segment 14, greatly reducing the construction period of the micropile method and reducing the cost. This is advantageous in achieving this.

Next, a second embodiment of the casing segment connection structure will be described with reference to FIG.
In the following embodiments, the same reference numerals are assigned to the same portions as those in the above-described embodiments, and the description thereof is omitted, and portions different from those in the above-described embodiments are mainly described.
In the second embodiment, a flange 2204 is provided on the casing joint 22 of the first embodiment.
That is, the male screws 2202 are formed at both ends in the longitudinal direction on the outer peripheral surface of the casing joint 22, and flanges 2204 are formed to bulge between the male screws 2202 at both ends.
The outer diameter of the flange 2204 is formed with a dimension equal to or smaller than the outer diameter of the casing segment 14 and is formed with an outer diameter equal to or larger than the outer diameter of the male screw 2202. Sometimes the flange 2204 is designed not to interfere with the wall surface of the drilled hole 20 and to resist.
When such a flange 2204 is provided, the flange 2204 can be gripped by a tool, and the casing joint 22 can be rotated more easily when the casing segment 14 is connected or removed.
Therefore, the casing segment 14 can be easily added or removed at the time of drilling, and the casing segment 14 can be easily removed at the time of pulling out, which is advantageous for increasing the drilling efficiency, and advantageous for increasing the pulling efficiency of the casing segment 14. .

Next, a third embodiment will be described with reference to FIG.
In the third embodiment, a chamfer 2206 is provided on the casing joint 22 of the first embodiment.
That is, chamfers 2206 are formed at both axial ends of the inner peripheral surface of the drill insertion hole 22A.
According to the third embodiment, it is advantageous to smoothly pass the drilling drill 16 through the casing joint 22, and therefore the drilled hole 20 reaches a predetermined depth of the load support layer 26. This is advantageous in increasing the efficiency of the drilling operation of the hole drill 16 performed after the drilling.

Next, a fourth embodiment will be described with reference to FIG.
In 4th Embodiment, the collar part 22C which covers the internal thread 1402 is provided in the casing joint 22 of 1st Embodiment.
That is, the casing joint 22 has a male screw portion 22B in which a male screw 2202 is formed, and flange portions 22C formed at both ends in the longitudinal direction of the male screw portion 22B.
The flange portion 22 </ b> C is a female screw that is exposed to the inside of the casing segment 14 in a state where end portions of adjacent casing segments 14 in the longitudinal direction are coupled by the casing joint 22 by screwing the male screw 2202 to the female screw 1402. 1402 is provided to cover.
Note that a chamfer 2206 is formed at the end portion of the inner peripheral surface of the flange portion 22C in the same manner as in the third embodiment, which is advantageous in increasing the efficiency of the drawing operation of the hole drill 16.
According to the fourth embodiment, it is possible to prevent the grout material G from entering the female screw 1402 at the end of the casing segment 14 by the flange portion 22C, which is advantageous in increasing the efficiency of the work of adding and removing the casing segment 14. It becomes.

Next, a fifth embodiment will be described with reference to FIG.
In the fifth embodiment, the stopper member 30 is provided inside the longitudinal end of the casing segment 14.
The stopper member 30 has a cylindrical shape in which a hole 3002 having a dimension equal to or larger than the inner diameter of the drill insertion hole 22A is formed.
The stopper member 30 is in contact with the longitudinal end of the casing joint 22 in a state where the adjacent casing segments 14 are connected by the casing joint 22 by the male thread 2202 being screwed to the female thread 1402. The internal thread 1402 exposed inside is covered.
The stopper member 30 is attached to the inside of the casing segment 14 by various conventionally known means such as an adhesive, welding, and screw connection, or is provided integrally with the casing segment 14.
One end in the longitudinal direction of the stopper member 30 is formed as an abutting portion 3004 that can abut on the end in the longitudinal direction of the casing joint 22, and the other end in the longitudinal direction is chamfered in the same manner as in the third embodiment. 3006 is formed, which is advantageous in increasing the efficiency of the drawing operation of the hole drill 16.
According to the fifth embodiment, similar to the fourth embodiment, the stopper member 30 can prevent the grout material G from entering the internal thread 1402 at the end of the casing segment 14, and the casing segment 14 can be added. This is advantageous in increasing the efficiency of the removal work.

12 …… Cutter for outer side drilling 14 …… Case segment 1402 …… Female thread 16 …… Drilling drill 18 …… Rod 20 …… Drilled hole 22 …… Case joint 22A …… Drill insertion hole 22B …… Male screw Part 22C …… Bridge 2202 …… Male thread 2204 …… Flange 2206 …… Chamfer 2208 …… Bridge 24 …… Soft layer 26 …… Load bearing layer 30 …… Stopper member

Claims (3)

Casing segment connection structure in the micropile method,
A female thread is formed on the inner peripheral surface of the longitudinal end of the casing segment,
A hollow cylindrical casing joint whose outer diameter is equal to or smaller than the outer diameter of the casing segment is provided,
A drill insertion hole having an inner diameter larger than the diameter of the drilling drill at the tip of the rod inserted into the casing segment is formed through the casing joint,
A male screw that can be screwed into the female screw is formed on the outer peripheral surface of the casing joint,
The longitudinal ends of adjacent casing segments are detachably connected by the casing joint by screwing the male screw into the female screw ,
The casing joint has a male screw part in which the male screw is formed, and flanges formed at both ends in the longitudinal direction of the male screw part,
In the state where the end portions of adjacent casing segments in the longitudinal direction are connected by the casing joint by the male screw being screwed to the female screw, the flange portion has the female screw exposed inside the casing segment. cover,
The connecting structure of the casing segment in the micropile method characterized by this. Casing segment connection structure in the micropile method,
A female thread is formed on the inner peripheral surface of the longitudinal end of the casing segment,
A hollow cylindrical casing joint whose outer diameter is equal to or smaller than the outer diameter of the casing segment is provided,
A drill insertion hole having an inner diameter larger than the diameter of the drilling drill at the tip of the rod inserted into the casing segment is formed through the casing joint,
A male screw that can be screwed into the female screw is formed on the outer peripheral surface of the casing joint,
The longitudinal ends of adjacent casing segments are detachably connected by the casing joint by screwing the male screw into the female screw ,
The casing joint is connected to the inner peripheral surface of the longitudinal end portion of the casing segment by connecting the longitudinal end portion of the adjacent casing segment to the internal thread by the male joint being screwed into the internal thread. A cylindrical stopper member is attached which covers the female screw exposed to the inside of the casing segment in contact with the longitudinal end portion of the drill hole and has a hole having an inner diameter larger than the inner diameter of the drill insertion hole. Yes,
The connecting structure of the casing segment in the micropile method characterized by this. The male threads are respectively formed at both ends in the longitudinal direction on the outer peripheral surface of the casing joint.
A flange having an outer diameter equal to or larger than the outer diameter of the male screw and equal to or smaller than the outer diameter of the casing segment is formed between the male screws at both ends in the longitudinal direction on the outer peripheral surface of the casing joint.
The connecting structure of the casing segments in the micropile method according to claim 1 or 2,

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