JP6501940B2 - Addition method and connection structure of casing segment in micro pile method - Google Patents

Description

  The present invention relates to a method of joining casing segments in a micropile method and a connection structure of casing segments.

The micro pile method is a generic term for small diameter cast-in-place piles with a diameter of 300 mm or less, and because it can be built in a narrow space, can be built in a narrow space, and can be built without stopping the functions of existing structures. , It is used for various applications including earthquake-resistant reinforcement and ground reinforcement of existing structures, stabilization of slopes, etc.
In the micropile method, first, the first rod having a drilling drill attached to its tip is inserted into the inside of the first casing segment whose tip outer peripheral portion is the cutter for outer drilling, and those first The steps of drilling while rotating the casing segment and the rod and while injecting water are performed.
Then, at a 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, and the casing segment and The steps of rotating the rod and drilling while injecting water are performed.

Next, when the drilled hole has reached a predetermined depth, the step of pulling the drill with the rod out of the interior 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 step of drawing out the casing segment by a predetermined length is performed while filling the grout material.
In such a micropile method, connection of the casing segments is conventionally performed using a hollow cylindrical casing joint having an outer diameter larger than the outer diameter of the casing segments.
That is, connection of the casing segments is performed by screwing internal threads on the inner peripheral surfaces of both ends in the longitudinal direction of the casing joint with the external threads on the outer peripheral surfaces of the adjacent casing segments.

Patent No. 4010383

Therefore, in the conventional micropile method, at the time of drilling, the casing joint protruding from the outer peripheral surface of the casing segment at the connection portion of the casing segment becomes a resistance, which is disadvantageous in enhancing the drilling efficiency.
In addition, when the casing segment is pulled out after drilling, the casing joint protruding from the outer peripheral surface of the casing segment at the connection portion of the casing segment interferes with the wall surface of the drilling hole and collapses the wall surface. The above is disadvantageous, and the casing joint interferes with the drilled wall surface, which is disadvantageous in enhancing 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, 18 casing segments are required and 17 casing joints are required even if a casing segment having a length of 3 m is used.
Therefore, as the number of casing joints increases as drilling is performed, the resistance of the casing joints is generated at a maximum of 17 places at the time of drilling, and also when the casing segment is pulled out, the casing joints interfere with the drilled wall surface And the resistance of the casing joint occurs at a maximum of 17 points, and some improvement is desired.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to improve the drilling efficiency of the casing segment in the micropile method and to improve the drawing efficiency of the casing segment. It is an object of the present invention to provide a method for connecting casing segments and a connecting structure in a micropile method.

In order to achieve the above object, the invention according to claim 1 is characterized in that the first casing segment whose tip outer peripheral portion is a cutter for outer drilling and the inner side of the casing segment are attached with a drilling drill at the tip. And drill holes while rotating the first casing segment and the rod so that the second casing segment can be detached at the end of the first casing segment along with drilling. While connecting, the second rod is detachably connected to the end of the first rod, and drilling is performed while rotating the casing segment and the rod, and then the casing segment and the rod are sequentially added together with the drilling. After drilling to a predetermined depth, pull out the drill with the rod and fill the grout with the casing segment A micropile method in which a fixed length drawing is performed, and connection of a casing segment is inserted into a casing segment having an outer diameter equal to or less than the outer diameter of the casing segment to allow movement of the drilling drill. Using a hollow cylindrical casing joint through which a drill insertion hole of a certain size is formed, and the casing joint is made by detachably connecting the inner peripheral surfaces of the ends of the casing segments I assume.
In the invention according to claim 2, a female screw is formed on the inner peripheral surface of the end in the longitudinal direction of the casing segment, and a male screw capable of being screwed on the female screw is formed on the outer peripheral surfaces of both ends in the longitudinal direction of the casing joint. The connection of the inner peripheral surfaces of the ends of the casing segments by the casing joint is achieved by screwing the external threads at both ends in the longitudinal direction of the casing joint to the internal threads of the longitudinal ends of the adjacent casing segments. It is characterized by being performed.
The invention according to claim 3 is the connection structure of the casing segments in the micropile method, wherein a female screw is formed on the inner peripheral surface of the end in the longitudinal direction of the casing segment, and the outer diameter is equal to or less than the outer diameter of the casing segment. A hollow cylindrical casing joint, the casing joint being formed with 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 inside of the casing segment; An external thread is formed on the outer peripheral surface of the joint so as to be able to be screwed into the internal thread, and longitudinal end portions of adjacent casing segments are releasably connected by the casing joint by the external thread being screwed into the internal thread. It is characterized by
Further, in the invention according to claim 4, the male screw is formed on both ends in the longitudinal direction on the outer peripheral surface of the casing joint, and an outer diameter is formed between the male screws on both ends in the longitudinal direction on the outer peripheral surface of the casing joint. A flange having a diameter not less than the outer diameter of the male screw and not more than the outer diameter of the casing segment is formed.
The invention of claim 5, wherein the axial ends of the inner circumferential surface of the drill insertion hole, you characterized in that chamfers are formed.

According to the first aspect of 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 inside of the casing segment, it projects from the outer peripheral surface of the casing segment as before. The elimination of the casing joint is advantageous in enhancing the drilling efficiency and the extraction efficiency of the casing segment.
According to the second aspect of the present invention, since the external thread of the casing joint is screwed to the internal thread on the inner peripheral surface of the end of the casing segment, the ends of the casing segments are reliably connected by a simple configuration. it can.
According to the third aspect of the present invention, the ends of the casing segments can be securely connected with a simple configuration, which is advantageous in enhancing the drilling efficiency and the casing segment drawing efficiency in the micropile method.
According to the fourth aspect of the present invention, since the flange can be gripped by the tool, it is advantageous in enhancing the efficiency of the work of adding and removing the casing segment.
According to the invention of claim 5, wherein the drilling drills, that advantageously the Do on to smoothly pass through the casing joint.

(A)-(G) are explanatory drawings of a micro pile method. It is explanatory drawing of the cutter for outer side drilling of the 1st casing segment front-end | tip, and the drilling drill of the front-end | tip of the 1st rod. In the connection structure of the casing segment according to the first embodiment, (A) shows the end of the adjacent casing segment and the casing joint, and (B) shows the end of the adjacent casing segment the casing joint It is explanatory drawing connected by. It is an explanatory view of a connection structure of a casing segment of a 2nd embodiment, and (A) is an explanatory view of an end of an adjacent casing segment and a casing joint, and (B) is an end of the adjacent casing segment a casing joint. It is explanatory drawing connected by. It is an explanatory view of a connection structure of a casing segment of a 3rd embodiment, and (A) is an explanatory view of an end of an adjacent casing segment and a casing joint, and (B) is an end of the adjacent casing segment a casing joint. It is explanatory drawing connected by. In the connection structure of the casing segment of the fourth embodiment (A) shows the end of the adjacent casing segment and the casing joint, (B) shows the end of the adjacent casing segment the casing joint It is explanatory drawing connected by. In the connection structure of the casing segment of the fifth embodiment (A) shows the end of the adjacent casing segment and the casing joint, (B) shows the end of the adjacent casing segment the casing joint It is explanatory drawing connected by.

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

As shown in FIG. 1 (A) and FIG. 2, the inside of the first elongated hollow cylindrical steel casing segment 14 whose outer periphery 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 while rotating the casing segment 14 and the rod 18, and while injecting water, the outer drilling cutter 12 and the drilling A step of drilling the hole 20 with the hole drill 16 is performed.
Then, as shown in FIGS. 1 (B) and 1 (C), the next elongated hollow cylindrical steel casing segment 14 can be attached to and removed from the end of the casing segment 14 whenever the hole 20 has a predetermined depth. And the next rod 18 is detachably connected to the end of the rod 18, and the casing segment 14 and the rod 18 are rotated, and the water is injected while the cutter for the outer hole drilling is performed. A step of drilling the hole 20 by the step 12 and the drilling drill 16 is performed.

In the present embodiment, as shown in FIGS. 3A and 3B, a drill insertion hole having a size that allows connection of the casing segment 14 to be inserted into the interior of the casing segment 14 and allows movement of the drilling drill 16. A hollow cylindrical casing joint 22 is formed through which 22A is formed, and the inner peripheral surfaces of the ends of the casing segment 14 are detachably connected.
A plurality of casing segments 14 are connected to constitute a casing C.
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 along with the rod 18 is inserted into the casing C. A process of pulling out of the apparatus is performed.
Next, if necessary, a reinforcing material such as a reinforcing bar is disposed inside the casing C over the entire length of the casing C.

Next, as shown in FIG. 1D, grout material G is filled in the inside of the casing C using a tremy pipe (not shown).
As the grout material G, cement milk, mortar material, concrete material mixed with small diameter aggregate can be used.
Next, as shown in FIG. 1E, a step of drawing out the casing C while performing pressure injection of the grout material G into the inside of the casing C is performed.
The grout material G is preferably pressurized at such a pressure that the grout material G adheres to the wall surface of the drilled hole 20 and the bonding between the grout material G and the ground becomes strong.
Withdrawal of the casing C holds the lower casing segment 14 in a non-rotatable manner when the upper end of the lower casing segment 14 of the vertically adjacent casing segments 14 is located on the ground, and the upper casing segment 14 , And removing the upper casing segment 14 with respect to the lower casing segment 14. When the upper casing segment 14 is removed, the casing joint 22 is also removed.
The plurality of upper casing segments 14 are removed together with the casing joint 22, and the lower end of the lowermost first casing segment 14 is the top of the load support layer 26 as shown in FIG. The drawing of the casing C is finished when it approaches.

Next, as shown in FIG. 1 (F), the casing C is pushed back by a predetermined amount in the grout material G pressure-filled with the grout material G, and a portion enclosed by the casing C, and the casing Between the part not surrounded by C, a part having an intermediate structure is created.
Then, by hardening the grout material G, the pile body 30 having the ground joint portion 30A with the grout material G is obtained.
Next, as shown in FIG. 1 (G), a steel pressure receiving plate 32 is joined to the upper end of the casing C by welding, and a connection structure is formed to connect the pile head of the pile 30 to the structure. Be done.

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

The casing joint 22 connecting the casing segments 14 has a hollow cylindrical shape, and the outer diameter is equal to or less than the outer diameter of the casing segment 14, and the drill insertion hole 22A having a size permitting movement of the drilling drill 16 inside is It is formed through.
On the outer peripheral surface of the casing joint 22, an external thread 2202 that can be screwed to the internal thread 1402 of the casing segment 14 is formed over the entire length in the longitudinal direction of the casing joint 22.
The longitudinal ends of the adjacent casing segments 14 are simply and reliably connected by the casing joint 22 by screwing the male threads 2202 into the female threads 1402.

In the present embodiment, the casing joint 22 is inserted into the casing segment 14 in a state in which the casing segment 14 is connected in order to connect the inner peripheral surfaces of the ends of the casing segment 14 with the casing joint 22. Become.
Then, after drilling, the drilling 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 because the drilling drill 16 is pulled out together with the rod 18. Is used.
That is, conventionally, since the ends of the casing segment 14 are connected with the casing joint 22 located on the outer peripheral surface of the casing segment 14 without being positioned inside the casing segment 14, the drilling drill 16 An outer diameter that can move inside of 14 is used.
On the other hand, in the present embodiment, since the drilling drill 16 has to have a size that can pass through the drill insertion hole 22A of the casing joint 22 disposed inside the casing segment 14, a conventionally used drilling drill A drilling drill 16 having a smaller outside diameter than that of 16 will be used.

Theoretically, in the conventional micropile method, the inner circumferential surface of an annular recess to be drilled by the outer drilling cutter 12 and the inner circumferential surface of a cylindrical recess to be drilled by the drilling drill 16 In the meantime, an annular wall remains corresponding to the thickness of the casing segment 14. The annular wall portion is considered to be collapsed by the vibration at the time of drilling, or by the contact of the side portion of the outer drilling cutter 12 or the side portion of the drilling drill 16, and the outer drilling cutter 12 The hole of the inside diameter corresponding to the outside diameter of the hole is drilled smoothly.
On the other hand, in the micropile method of the present embodiment, the inner peripheral surface of the annular recess to be drilled by the outer drilling cutter 12 and the inner periphery of the cylindrical recess to be drilled by the drilling drill 16 Between the faces remains an annular wall of a thickness that is the sum of the thickness of the casing segment 14 and the thickness of the casing joint 22. As in the conventional case, 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. The hole 20 having an inner diameter corresponding to the outer diameter of the hole cutter 12 is drilled smoothly.
Therefore, in the present embodiment, although the drilling drill 16 having a smaller outside diameter than the conventional one is used, the bore of the inner diameter corresponding to the outer diameter of the outer drilling cutter 12 is smoothed as in the conventional case. It is pierced.

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 inside of the casing segment 14, from the outer peripheral surface of the casing segment 14 as in the prior art There is no protruding casing joint. Therefore, at the time of drilling, the problem that the casing joint becomes a resistance at the connection portion of the casing segment 14 is eliminated, which is advantageous in enhancing the drilling efficiency.
Similarly, when the casing segment 14 is pulled out after drilling, there is no casing joint projecting from the outer peripheral surface of the casing segment 14, so that the casing joint interferes with the wall surface of the hole 20 bored and the wall surface is broken Also, the problem that the casing joint interferes with the wall surface of the hole 20 at the time of drawing out and becomes resistance is eliminated, which is advantageous in enhancing the drawing efficiency of the casing segment 14.
In addition, since the external thread 2202 of the casing joint 22 is screwed to the internal thread 1402 on the inner circumferential surface of the end of the casing segment 14, the end portions of the casing segment 14 can be connected by a simple configuration using the casing joint 22. It can be connected securely.

Specifically, for example, in order to drill a depth of 54 m, 18 casing segments 14 are required and 17 casing joints 22 are needed even if the casing segment 14 having a length of 3 m is used Become.
Therefore, as the number of casing joints 22 increases as drilling is performed, it is possible to eliminate the conventional problem that the resistance of the casing joints 22 occurred at the maximum at 17 places during drilling, and to pull out the casing segment 14 Also in this case, there are at most 17 places where the casing joint 22 interferes with the wall surface of the drilled hole, and the conventional problem that the resistance of the casing joint 22 occurred at 17 places at the maximum can be resolved.
That is, it is advantageous in enhancing the drilling efficiency by the outer drilling cutter 12 and the drilling drill 16, and advantageous in enhancing the drawing efficiency of the casing segment 14, greatly shortening the construction period of the micropile method, and reducing the cost. It is advantageous in

Next, a second embodiment of the connecting structure of the casing segments will be described with reference to FIG.
In the following embodiments, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and the descriptions thereof will be omitted, and parts different from the above-described embodiment will be 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 respectively formed on both ends in the longitudinal direction on the outer peripheral surface of the casing joint 22, and the flanges 2204 are formed so as to bulge between the male screws 2202 on both ends.
The outer diameter of the flange 2204 is equal to or smaller than the outer diameter of the casing segment 14 and is equal to or larger than the outer diameter of the male screw 2202. Sometimes the flange 2204 does not interfere with the wall surface of the drilled hole 20 and does not resist it.
When such a flange 2204 is provided, the flange 2204 can be gripped by a tool, and the rotation operation of the casing joint 22 when connecting and removing the casing segment 14 can be performed more easily.
Therefore, it is possible to easily add the casing segment 14 at the time of drilling and to remove the casing segment 14 at the time of pulling out, which is advantageous in enhancing the drilling efficiency and advantageous in enhancing the pulling efficiency of the casing segment 14 .

Next, a third embodiment will be described with reference to FIG.
In the third embodiment, the casing joint 22 of the first embodiment is provided with a chamfer 2206.
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 allow the drilling drill 16 to pass smoothly through the casing joint 22, so that the drilled holes 20 reach a predetermined depth of the load support layer 26. It is advantageous in increasing the efficiency of the drawing operation of the drilling drill 16 to be performed later.

Next, a fourth embodiment will be described with reference to FIG.
In the fourth embodiment, the casing joint 22 according to the first embodiment is provided with a collar 22C that covers the female screw 1402.
That is, the casing joint 22 has an external thread portion 22B in which an external thread 2202 is formed, and flange portions 22C formed on both ends in the longitudinal direction of the external thread portion 22B.
The flange 22C is a female screw exposed inside the casing segment 14 in a state where the longitudinal ends of the adjacent casing segments 14 are connected by the casing joint 22 by the male screw 2202 being screwed onto the female screw 1402. It is provided so as to cover 1402.
A chamfer 2206 is formed at the end of the inner peripheral surface of the flange 22C as in the third embodiment, which is advantageous in enhancing the efficiency of the drawing operation of the drilling drill 16.
According to the fourth embodiment, the gutter 22C can prevent the grout material G from entering the internal thread 1402 at the end of the casing segment 14, which is advantageous in increasing the efficiency of the joining and removing operations of 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 tubular 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 abuts on 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 screwing the male screw 2202 to the female screw 1402, and the stopper member 30 is It covers a female screw 1402 exposed to the inside.
The stopper member 30 is attached to the inside of the casing segment 14 by various means known in the prior art such as an adhesive, welding, screw connection, or is provided integrally with the casing segment 14.
One end of the stopper member 30 in the longitudinal direction is formed as an abutting portion 3004 that can abut the end of the casing joint 22 in the longitudinal direction, and the other end in the longitudinal direction is chamfered in the same manner as the third embodiment. 3006 is formed, which is advantageous in increasing the efficiency of the drawing operation of the drilling drill 16.
According to the fifth embodiment, as in 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 joining operation of the casing segment 14 is performed. And it is advantageous in increasing the efficiency of the removal work.

12: Cutter for outer drilling 14: Casing segment 1402: Female screw 16: Drill drill 18: Rod 20: Drilled hole 22: Casing joint 22A: Drill insertion hole 22B: Male screw Section 22C · · · Section 2202 · · · Male thread 2 204 · · · · · · · · · · 2 22 · · · 2 24 · · · 24 soft layer 26

Claims (5)

A first casing segment whose tip outer peripheral portion is an outer drilling cutter, and a first rod which is inserted into the inside of the casing segment and has a drilling drill attached to the tip, and those first casings While rotating the segment and the rod, drilling is performed, and the second casing segment is detachably connected to the end of the first casing segment along with the drilling while the second casing segment is connected to the end of the first rod. The rods are detachably connected, drilling is performed while rotating the casing segment and the rod, and thereafter the casing segment and the rod are sequentially joined together with the drilling,
A micropile method in which, after drilling to a predetermined depth, the drilling drill is withdrawn together with the rod, and the casing segment is pulled out while filling grout material,
A hollow cylindrical shape having an outer diameter equal to or less than the outer diameter of the casing segment and connected with the casing segment, in which a drill insertion hole having a size to allow movement of the drilling drill is inserted. Using a casing joint, the casing joint is formed by detachably connecting the inner peripheral surfaces of the ends of the casing segments,
A method of joining casing segments in a micropile method characterized by An internal thread is formed on the inner peripheral surface of the longitudinal end of the casing segment,
An external thread that can be screwed to the internal thread is formed on the outer peripheral surface of each end of the casing joint in the longitudinal direction,
The connection of the inner peripheral surfaces of the ends of the casing segments by the casing joint is performed by screwing the external threads at both ends in the longitudinal direction of the casing joint to the internal threads of the longitudinal ends of the adjacent casing segments. Be
A method of adding casing segments in the micropile method according to claim 1, characterized in that: Connection structure of casing segments in micro pile method,
An internal thread is formed on the inner peripheral surface of the longitudinal end of the casing segment,
A hollow cylindrical casing joint having an outer diameter equal to or less than the outer diameter of the casing segment;
The casing joint is formed with a drill insertion hole having an inner diameter larger than the diameter of the drilling drill of the tip of the rod inserted into the inside of the casing segment,
An external thread that can be screwed to the internal thread is formed on the outer peripheral surface of the casing joint,
Longitudinal ends of adjacent casing segments are releasably connected by the casing joint by screwing the male screw to the female screw.
Connection structure of casing segments in the micropile method characterized by The male screw is formed on both ends in the longitudinal direction on the outer peripheral surface of the casing joint,
A flange having an outer diameter equal to or greater than the outer diameter of the male screw and equal to or smaller than an 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 connection structure of the casing segment in the micropile method of Claim 3 characterized by the above-mentioned. Chamfers are formed on both axial ends of the inner peripheral surface of the drill insertion hole,
The connection structure of the casing segment in the micropile method of Claim 3 or 4 characterized by the above-mentioned.

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