JP2011026911A - Construction method of rotary penetrating pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To construct a rotary penetrating pile while preventing grout material discharging holes disposed in the circumference wall of the rotary penetrating pile from being blocked by earth and sand. <P>SOLUTION: On the inside of an outer tube having a plurality of grout material discharging holes in the circumference wall, an inner tube with a diameter smaller than an inside diameter of the outer tube is inserted while allowing recovery of the inner tube, and the end of a clearance formed between the outer tube inner wall and the inner tube outer wall is closed. The outer tube and the inner tube are attached to a drilling machine to perform rotary penetrating to the predetermined depth in the underground, and the earth and sand occurring along with the rotary penetrating action are taken into the hollow part of the inner tube. After completing the rotary penetrating action, the inner tube is pulled out from the outer tube, and pressure injection of grout material to the outer tube is carried out so that the grout material is discharged from the grout material discharging holes and the outer tube end part to grout the peripheral ground. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for constructing a rotation penetration type steel pipe pile (rotation penetration pile) that penetrates into the ground while rotating, and in particular, prevents the grout material discharge hole from being blocked by the earth and sand of the ground, It is related with the construction method of the rotation penetration pile which enables grout to the surrounding ground.

  For the purpose of improving soft ground, there are steel pipe piles that rotate and penetrate into the ground. Such a steel pipe pile is a rotary penetration pile that is driven into the ground in a form that rotates and penetrates the steel pipe pile itself without using other drilling means, and can be easily placed on the ground with a relatively inexpensive and small boring machine, There is a merit that there is little noise and earth removal. Fig.11 (a) is explanatory drawing of the rotation penetration pile proposed by this applicant, (b)-(d) is an exploded view (refer patent document 1). The rotary penetrating pile 10 is hollow and is, for example, a steel pipe pile having a total length of 3000 to 6000 mm, a diameter of 114.3 mm, and a thickness of 4.5 mm so that it can be separated into a lower fixing length portion 11, an upper free length portion 12 and an upper blade portion 13. It has become.

The lower fixing length portion 11 has a length of 2000 to 5000 mm, a spiral lower blade portion 11a is formed at the tip, and a circular node protrusion 11b at a first pitch is formed on the outer periphery of the lower fixing length portion 11. A grout material discharge hole 11c with a check valve mechanism is formed at a second pitch on the peripheral wall of the lower fixing length portion 11, and an upper free length portion 12 and the other end portion of the lower fixing length portion 11 are formed. A joint 11d (see FIG. 11B) having a screw configuration for connection is formed.
The upper free length portion 12 has a length of about 1000 mm, and a joint 12a (see FIG. 11 (d)) having a screw structure for connecting to the lower fixing length portion 11 is formed at the lower end. As shown in FIG. 11C, the upper blade portion 13 includes an upper blade 13a and a joint portion 13b, and the lower fixing length portion 11 and the upper free length portion 12 are connected via the joint portion 13b. The upper blade 13a is not always necessary.

  When the grout material is pressurized and injected after the rotation penetration pile 10 is rotated and penetrated into the ground, the grout material is discharged from the plurality of grout material discharge holes 11c into the ground loosened by the lower blade 11a. Specifically, as shown in FIG. 12, a uniform grout column 15 is formed, and a reliable supporting force can be obtained. That is, it is possible to grout with the penetration of the pile while the ground around the pile is uniformly agitated, and to obtain a large load transmission performance by adhering to the uniform grout.

  However, the grout material discharge hole 11c on the tip side of the rotary penetrating pile 10 is actually blocked by earth and sand, and the grout to the ground around the tip becomes insufficient. That is, as described above, the rotary penetrating pile has the advantage of no soil removal or less soil removal, and the excavated soil is hardly discharged to the ground. Further, it is desirable that the resistance to penetrate into the ground by the rotational force is as small as possible. Thus, in the rotary penetration pile 10 with little penetration resistance and little soil discharge, the soil and sand 16 of the ground excavated by the pile body itself enters the inside of the steel pipe of the lower fixing length portion 11 as shown by the dotted line in FIG. The grout material discharge hole 11c formed in the peripheral wall on the side is closed. As a result, the grouting depth outside the pipe is not determined, in particular, the intruded earth and sand is consolidated in the vicinity of the lower end of the steel pipe, and a region where the grout material is not injected is formed at the tip of the rotary penetrating pile 10, and the required tip support force, In other words, the pushing support force and the pulling support force cannot be secured.

  As a conventional technique, there is a screw-in type steel pipe pile that prevents earth and sand from entering the inside of the steel pipe (see Patent Document 2). This screw-type steel pipe pile has an upper steel pipe and a lower steel pipe, and uses the propulsive force of the lower steel pipe in the underground direction to penetrate into the ground to a depth that does not completely embed the upper steel pipe. After penetrating, a solidified material such as concrete is placed in the upper steel pipe, and the upper steel pipe and the lower steel pipe protruding inside are fixed integrally. According to this conventional technology, when the upper steel pipe penetrates, the earth and sand are compressed in the lateral direction outside the pipe, so that the earth and sand do not enter the upper steel pipe, and there is no need to clean the upper steel pipe when placing concrete. become. However, the prior art does not prevent earth and sand from entering the lower steel pipe.

  Patent Document 2 discloses, as another example, a technique in which an auger head is inserted into a lower steel pipe and protruded from a tip to excavate, and a grout material is discharged from a discharge port provided in the auger head. According to this prior art, it is possible to discharge the grout material from the lower end of the lower steel pipe to the ground, but it is not possible to obtain a predetermined fixing length by turning the grout material around the lower steel pipe. In order to obtain a predetermined fixing length, it is necessary to provide a grout material discharge hole in the peripheral wall of the steel pipe. However, the above prior art does not prevent the grout material discharge hole from being blocked by earth and sand. Further, in the prior art, it is necessary to simultaneously perform the lower steel pipe placement and the auger excavation, and there is a problem that the construction becomes complicated.

JP 2008-57113 A JP 2007-77803 A

From the above, an object of the present invention is to prevent the grout material discharge hole provided in the peripheral wall of the rotary penetrating pile from being blocked by earth and sand.
Another object of the present invention is to allow the grout material to be discharged from the tip of the rotary penetrating pile in addition to the grout material discharge hole, and to ensure sufficient indentation support force and pull-out support force.

The present invention is a method for constructing a rotary penetrating pile that is inserted into the ground while being rotated, and an inner pipe having a smaller diameter than the inner diameter of the outer pipe can be collected inside the outer pipe having a plurality of grout material discharge holes on the peripheral wall. Inserting and closing a tip of a gap formed between the inner wall of the outer tube and the outer wall of the inner tube, a step of attaching the outer tube and the inner tube to a drilling machine and rotating and penetrating to a predetermined depth in the ground, The step of taking the earth and sand generated by the rotation penetration operation into the hollow portion of the inner tube, the step of pulling out the inner tube from the outer tube after the completion of the rotation penetration operation, pressurizing and injecting the grout material into the outer tube, A step of discharging from the grout material discharge hole and the outer tube tip to grout the surrounding ground.
The inner pipe is formed by connecting a plurality of single pipes having a predetermined length so that they can be disassembled, and a closing means for closing the gap is provided at the distal end of the inner pipe.

According to the present invention, the double-pipe structure is used, and the tip of the gap formed between the inner wall of the outer tube and the outer wall of the inner tube is closed. The grout discharge hole provided in the peripheral wall of the outer tube is not blocked by earth and sand. As a result, the grout material can be evenly grouted to the ground around the pile by collecting the inner pipe with earth and sand and then injecting the grout material into the outer pipe under pressure, ensuring a large pushing support force and pulling support force. can do.
Moreover, according to this invention, it becomes possible to discharge a grout material not only from a grout material discharge hole but also from the front-end | tip of an outer tube | pipe, and it can ensure a bigger pushing support force and drawing | extracting support force.

It is set condition explanatory drawing of the rotation penetration pile used for the construction method of this invention. It is an exploded view of a lower pile. It is the perspective view seen from the lower cross section and lower diagonal direction of a lower pile. It is an exploded view of the whole rotation penetration pile. It is a connection state explanatory view of each part. It is explanatory drawing which rotationally penetrates a rotation penetration pile to the ground using a rotary drilling machine. It is explanatory drawing of the construction method of a rotation penetration pile. It is attachment explanatory drawing to a drilling machine of a lower pile. It is a construction state explanatory view of the present invention. It is an internal state explanatory drawing of the rotation penetration pile at the time of construction. It is explanatory drawing of the rotation penetration pile which has been proposed. It is ideal construction state explanatory drawing of the rotation penetration pile of FIG. It is actual construction state explanatory drawing of the rotation penetration pile of FIG.

FIG. 1 is an explanatory diagram of a set state of a rotary penetrating pile used in the construction method of the present invention, FIG. 2 is an exploded view of a lower pile, FIG. 3 is a lower cross-sectional view of the lower pile, and a perspective view seen from obliquely below, FIG. Is an exploded view of the entire rotary penetrating pile,
The rotation penetration pile 20 is provided with the lower pile 21 and the upper pile 22, and these piles are connected by screw coupling. The lower pile 21 includes an outer tube 31 and an inner tube 32 arranged in the outer tube.
A spiral blade 31a is formed at the tip of the outer tube 31, a circular node projection 31b is formed at the first pitch in the longitudinal direction on the outer periphery, and a check valve mechanism is provided at the second pitch. A grout material discharge hole 31c is formed, and a joint 31d (see FIG. 2) having a screw structure for connecting to the upper pile 21 is formed at the other end of the outer tube 31. The blade portion 31a is formed by plastic working so that the tip of the outer tube 31 projects outward, and a cut is made in the projecting portion to be bent spirally. The node protrusion 31b is provided for the purpose of improving the load transmission performance of the ground and the pile, and is formed by bead welding.

The inner tube 32 has a smaller diameter than the inner diameter of the outer tube, and is inserted and arranged so that it can be later withdrawn into the outer tube and collected. As shown in FIG. 2, the inner tube is configured by connecting a plurality of (three in the figure) single tubes 32 a _{1 to} 32 a ₃ having a predetermined length and can be disassembled. The distal end outer head of the single pipe 32a ₁ is formed a packing fixing ring RNG for fixing the rubber packing RBP of the closing member 32b is screw to attach the metal crown 32c is formed on the inner, the other end inside the other single A screw for connecting to the tube is formed. The closing member 32 b has an action of closing a gap formed between the outer tube 31 and the inner tube 32. Screws for connecting to other single tubes are formed inside both ends of the intermediate single tube 32a ₂ , and screws for connecting to other single tubes are formed inside one end of the uppermost single tube 32a _3. A screw for connecting a coupling 32d for coupling a boring rod is formed inside the other end.

The cylindrical metal crown 32c includes a bit BT (see FIG. 3B) and has a function of excavating the ground by rotation. The metal crown 32c, attached to the top of the single pipe 32a ₁ through the closing member 32b provided with a rubber packing RBP and O-ring, connecting each single tube 32a ₁ ~32a ₃ professional long coupling 32e for extension , it is possible to form the inner tube 32 by connecting the coupling 32d for boring rod coupled to a single tube 32a ₃ of the top. And if this inner pipe | tube 32 is inserted and set from the upper end part of the outer pipe | tube 31 as shown by the arrow of FIG. 2, the lower pile 21 will be formed. When the inner tube 32 is set in the outer tube 31, as shown in FIG. 3 (a), the gap 33 formed between the outer tube 31 and the inner tube 32 is closed by the closing member 32b. It does not enter this gap. In addition, as shown in FIG.3 (b), earth and sand enter in the inner pipe | tube 32 through the metal crown 32c.

The upper pile 22 has a function as an extended portion of the outer pipe 31 of the lower pile 21, and the circular protrusions 31 b are formed on the outer wall at the first pitch in the longitudinal direction like the outer pipe 31, and A grout material discharge hole 31c with a check valve mechanism is formed at the second pitch, and a joint 31e having a screw structure for connecting to the outer tube 31 is formed at the lower end portion. Further, a joint 31f (FIG. 4) having a screw structure for attaching a drilling machine (auger) 41 is formed at the upper end. A boring rod 35 for transmitting a rotational force to the inner pipe 32 of the lower pile 21 is set inside the upper pile 22.
As shown in FIG. 4, the boring rod 35 includes a rod-shaped main body portion 35 a, a connecting portion 35 b for connecting to the coupling 32 d of the inner tube 32, and a screw connecting portion 35 c for connecting to the drilling machine 41. And a bowl-shaped center riser 35d that is positioned at the center while suppressing the deflection of the boring rod.
As shown in FIG. 4, the lower pile 21 and the upper pile 22 are connected, then the boring rod 35 is connected to the inner pipe 32 of the lower pile through the upper pile 22, and finally the drilling machine 41 is connected to the upper pile 22. 1 and the boring rod 35 are connected to each other to complete the rotary penetrating pile shown in FIG. In addition, although the structure which has a lower pile and an upper pile was shown as the rotation penetration pile 20, an upper pile is not necessarily required by the penetration depth of a rotation penetration pile.

FIG. 5A is an explanatory diagram of the connection between the boring rod 35 and the inner pipe 32 in the lower pile 21. The connecting portion 35b of the boring rod 35 and the coupling 32d of the inner pipe 32 are connected by screws, and the boring rod 35 rotates. Is transmitted to the inner tube 32.
FIG. 5B is an explanatory diagram of a state in which the drilling machine 41 is connected to the upper pile 22 and the boring rod 35, and the tip of the block 41 b fixed to the rotating part 41 a of the drilling machine 41 is the boring rod 35. The block 41c that rotates together with the connecting portion 35c is screwed to the joint 31f of the upper pile 22 and the rotational force of the drilling machine 41 is independent of the upper pile 22 and the boring rod 35, respectively. To be communicated to.

  FIG. 6 is an explanatory view of rotating the rotary penetrating pile into the ground using the rotary drilling machine 41, and shows a state where the rotary penetration into the ground is completed. In the rotary penetration of the rotary penetration pile 20 into the ground, first, the outer pipe and the inner pipe of the lower pile 21 are respectively attached to the drilling machine 41 and rotated to a predetermined depth, and then the upper pile 22 is moved to the lower pile 21. It connects by connecting a boring rod to the inner pipe of a lower pile, attaching this upper pile and a boring rod to the drilling machine 41, respectively, and carrying out rotation penetration.

  Drawing 7 is an explanatory view of the construction method of a rotation penetration pile. First, the lower pile 21 is attached to the drilling machine 41. FIG. 8 is an explanatory view of attaching the lower pile 21 to the drilling machine. With the inner pipe 32 of the lower pile 21 set to the outer pipe 31, the tip of the block 41b of the drilling machine 41 is screwed to the coupling 32d of the inner pipe 32, and the block 41c is connected to the joint 31d of the outer pipe 31. And screw. In this state, the lower pile 21 is rotated and penetrated to a predetermined depth by the drilling machine 41 (FIG. 7 (a)). At the time of this rotation penetration, the earth and sand generated by the excavation of the blade 31a enters the hollow portion of the inner pipe 32.

Thereafter, as described with reference to FIG. 4, the upper pile 22 is connected to the lower pile 21, and the boring rod 35 is connected to the inner pipe 32 of the lower pile through the upper pile. Next, as described in FIG. 5 (b), the upper pile 22 and the boring rod 35 are respectively attached to the drilling machine 41 and are rotated and penetrated, thereby penetrating the rotary penetrating pile 20 into the ground (FIG. 7 (b)). . Even during the rotation penetration, the earth and sand enter the hollow portion of the inner tube 32.
When the penetration of the rotary penetration pile 20 is completed, the boring rod 35 and the inner pipe 32 are pulled out and collected (FIG. 7 (c)). Thereby, earth and sand do not exist in the inside of the rotation penetration pile 20.
After completion of the collection, as shown in FIG. 7 (d), if the mouth of the upper pile 22 is closed with a valve 42 and the grout is injected under pressure from the grout injection device 43, the grout material becomes grout material on the ground where the blades 31a are loosened. A uniform grout column 51 is formed so as to be discharged from the discharge hole 31c and also from the distal end portion of the outer pipe 31, and to surround the distal end over the entire length of the rotary penetrating pile 20, as shown in FIG. Thus, a reliable supporting force can be obtained.

FIG. 10 is an explanatory diagram of the internal state of the rotary penetrating pile 20 during construction. (A) is an internal state at the time of completion of penetration, and earth and sand have entered into the hollow portion of the inner tube 32. However, since the lower end portion of the gap 33 is blocked, the earth and sand do not enter, and the grout material discharge holes 31c formed in the peripheral wall of the outer tube 32 are not blocked by the earth and sand. (B) shows the internal state after the recovery of the inner pipe 32, no earth or sand has entered the outer pipe 32, and the grout material discharge holes 31c formed in the peripheral wall of the outer pipe 32 are blocked by the earth and sand. Not. (C) is a grouting state after the grouting pressurization, so that the grouting material is discharged from the grouting material discharge hole 31c and the tip of the outer pipe 31 to the ground where the blade 31a is loosened, and surrounds the rotary penetrating pile. A uniform grout is made.
The earth and sand taken into the inner pipe can be easily discarded by disassembling the inner pipe after collection, and the inner pipe can be used repeatedly.
Moreover, since it is the structure which collect | recovers an inner pipe | tube, at the time of penetrating to a predetermined depth or at an appropriate time, such as in the middle of penetrating, it is possible to visually check the soil quality and ground condition.

20 Rotating Penetration Pile 21 Lower Pile 22 Upper Pile 31 Outer Pipe 31a Blade Part 31b Node Protrusion 31c Grout Material Discharge Hole 32 Inner Pipe 35 Boring Rod 41 Drilling Machine (Auger)

Claims (3)

In the construction method of the rotation penetration pile that penetrates into the ground while rotating,
An inner tube having a diameter smaller than the inner diameter of the outer tube is removably inserted into the outer tube having a plurality of grout material discharge holes in the peripheral wall, and the tip of a gap formed between the inner wall of the outer tube and the outer wall of the inner tube Block the
Attach the outer and inner pipes to a drilling machine and rotate to a predetermined depth in the ground,
Incorporate the earth and sand generated by the rotation penetration operation into the hollow portion of the inner tube,
Pull out the inner tube from the outer tube after the rotation penetration operation is completed,
Injecting the grout material into the outer tube under pressure, and discharging the grout material from the grout material discharge hole and the outer tube tip to grout the surrounding ground.
The construction method of the rotation penetration pile characterized by this.   The method for constructing a rotary penetrating pile according to claim 1, wherein a plurality of single pipes are connected so as to be disassembled to form the inner pipe.   The construction method for a rotary penetrating pile according to claim 1, wherein a closing means for closing the gap is provided at the tip of the inner pipe.

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