JP2017014869A - Auger screw and ground reinforcement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auger screw and a ground reinforcement method that can achieve boring drilling while suitably reducing a soil removal amount, and thus attain superior workability.SOLUTION: An auger screw A comprises a screw shaft 2 which comprises a drilling bit 1 at a tip part and is supported rotatably on an axis O1, and a screw blade 3 which protrudes outward from an outer peripheral surface of the screw shaft 2 in one body and is provided spirally while twisted to a rear side in a sequential forward rotating direction from a front end side to a rear end side along the axis O1, the screw shaft 2 being formed in stages to be larger in diameter as arranged more on the rear end side than on the front end side along the axis O1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an auger screw and a ground reinforcement method.

  2. Description of the Related Art Conventionally, as a means for drilling and excavating underground, an earth auger excavation method in which an auger screw is rotated and screwed into the ground and excavated soil is excavated while being grounded using a rotational force is frequently used.

  In addition, the auger screw is generally formed in a cylindrical bar shape and has a drilling bit at the tip, and is supported integrally so as to be rotatable around the axis, and integrally protrudes outward from the outer peripheral surface of the screw shaft. The screw shaft is formed in a drill shape with a screw blade spirally provided so as to be twisted backward in the forward rotation direction sequentially from the front end side to the rear end side of the screw shaft.

  As a result, when the screw shaft is screwed into the ground while rotating in the positive direction around the axis, the excavated earth and sand are sequentially conveyed to the ground side by being guided by the spiral screw blade, and drilling and excavating while automatically discharging the soil. be able to.

  On the other hand, in order to promote excavation or to form a soil cement columnar body by mixing with earth and sand (ground improvement: ground reinforcement construction method), a method of excavating while injecting cement milk etc. through the screw shaft is often used. However, in this case, since the cement milk is mixed with the discharged soil transported to the ground, it is necessary to treat the discharged soil as industrial waste.

  On the other hand, an auger screw configured to reduce the amount of soil removal and compress the hole wall to prevent collapse by conveying the soil to the ground side with a screw blade and pressing it against the hole wall has been put into practical use. ing.

  For example, in Patent Document 1, the screw shaft is formed so as to taper toward the tip, and at the time of drilling excavation, the soil that is sequentially conveyed upward is pressed against the hole wall with the screw shaft that gradually increases in diameter. A drilling rig is disclosed.

JP 61-32229 A

  However, since the auger screw of the conventional excavator is simply tapered to the tip of the screw shaft toward the tip, the auger screw is formed in the hole wall between the tip end side and the rear end side of the tapered portion. The amount of soil to be pressed and the pressure are constantly changing, and large excavation resistance tends to occur. For this reason, for example, the soil is conveyed upward, and a large friction is generated between the screw shaft and the hole wall, and there is a possibility that jamming occurs frequently.

  Further, in the conventional ground reinforcement method described above, excavation is performed while cement milk or the like is injected through the screw shaft, and the soil cement columnar body is formed by mixing soil and cement milk. Or by pouring a slurry such as cement milk, the soil with high fluidity overflows on the ground and a lot of industrial waste is generated in many cases.

  Furthermore, with a stirrer that rotates while supporting an auger screw, it is difficult to form a short soil cement pillar by injecting slurry such as cement milk through the screw shaft, and build a small-scale building such as a house. In some cases, it cannot be applied to reinforcement or improvement of the ground.

  Also, in order to make a slurry by mixing cement-based solidifying material and water (on-site kneading), a plant is required, and further, excavation, pouring and agitation are carried out with a single construction machine. There are also inconveniences such as less construction amount.

  In view of the circumstances described above, an object of the present invention is to provide an auger screw and a ground reinforcement method capable of suitably excavating and excavating with a reduced amount of soil and realizing excellent workability.

  In order to achieve the above object, the present invention provides the following means.

  The auger screw according to the present invention has a drilling bit at the tip, is supported so as to be rotatable around the axis, and projects integrally from the outer peripheral surface of the screw shaft to the outside and from the tip in the axial direction. A screw blade provided in a spiral shape that is twisted to the rear side in the forward rotation direction sequentially toward the rear end side, and the diameter of the screw shaft increases from the front end side to the rear end side in the axial direction. It is formed in a multi-stage shape.

  In the present invention, the screw shaft is formed in a multistage shape having a diameter that increases as it is arranged from the front end side to the rear end side in the axial direction, so that the screw shaft rotates positively around the axis line and is excavated by the excavation bit at the front end portion. When the discharged soil is conveyed upward by the spiral screw blade, the amount of discharged soil that is sequentially transferred to the large diameter section and pressed against the hole wall and discharged to the ground can be greatly reduced.

  In addition, since the screw shaft is formed in a multistage shape that increases in diameter as it is arranged from the front end side to the rear end side in the axial direction, and the diameter of each step is constant, the soil pressed against the hole wall in each step The amount and pressure can be constant.

  Thereby, compared with the case where the conventional screw shaft is formed in the taper shape which becomes gradually large as it goes to the rear end side from the front end side, excavation resistance can be reduced. Therefore, it is possible to reliably prevent the occurrence of jamming and appropriately excavate the ground.

  Further, in the auger screw according to the present invention, the screw shaft is connected to each of the connecting portions of the small-diameter side section on the front end side adjacent to the axial direction and the large-diameter side section on the rear end side. It is desirable that the taper portion is formed to have a tapered portion that gradually decreases in diameter from the rear end side and is connected to the rear end side of the small diameter side section.

  In the present invention, the tapered portion is provided in each connecting portion of the small-diameter section on the front end side adjacent to the axial direction of the screw shaft and the large-diameter side section on the rear end side, that is, the step portion of each step. Even when the screw shafts are formed in a multi-stage shape, it becomes possible to smoothly convey and supply the soil from the adjacent small diameter side section on the front end side to the large diameter side section on the rear end side.

  Thereby, it can prevent that big excavation resistance generate | occur | produces in the level | step-difference part of each stage, and excavation resistance can be reduced reliably. In other words, it is possible to more reliably suppress the occurrence of jamming and the like to suitably drill and excavate the ground.

  In addition, since the taper portion is provided in the step portion of each step, the soil discharge can be pressed against the hole wall with a large pressing force when the soil discharge passes through the taper portion. The amount can be reduced.

  Furthermore, in the auger screw of the present invention, it is more preferable that the pitch of the screw blade is formed to be equal to or less than the outer diameter of the excavation bit.

  In this invention, since the pitch of the screw blades is set to be equal to or smaller than the outer diameter of the excavation bit, it is possible to reduce the conveying speed upward of the soil with respect to the rotational speed.

  Thus, even when the screw shaft is formed in a multi-stage shape having a large diameter so as to be arranged from the axial front end side to the rear end side, a large diameter on the rear end side from a small diameter side section on the adjacent front end side. It is possible to prevent the excavation from moving rapidly to the side section and generating large excavation resistance. That is, by setting the screw blade pitch of the screw shaft to be equal to or less than the outer diameter of the excavation bit, the excavation resistance can be further reliably reduced, and the ground is suitably drilled and excavated while suppressing occurrence of jamming and the like. It becomes possible.

  In the auger screw according to the present invention, it is further desirable that the small-diameter section on the front end side adjacent to the axial direction and the large-diameter section on the rear end side are detachably connected.

  In the present invention, it is configured by connecting the small diameter side section on the front end side and the large diameter side section on the rear end side so as to be separable, so that the screw shaft having the number of steps and the diameter as appropriate, and A screw blade (screw shaft part) can be easily formed. Moreover, since the screw shaft part of each step can be manufactured individually, it is possible to reduce the manufacturing cost.

  The ground reinforcement method of the present invention is a method of reinforcing a ground by forming a columnar body in the ground, and drilling and excavating the ground using any of the auger screws described above, and ready mixed concrete is formed in the excavation hole. The columnar body is formed by filling.

  In the present invention, by using the auger screw described above, the hole wall is consolidated, and an excavation hole that does not easily collapse can be formed. Thereby, the auger screw can be pulled out and the inside of the excavation hole can be held in an empty state, and ready mixed concrete can be injected and filled into the excavation hole.

  In the auger screw according to the present invention, the screw shaft is formed in a multistage shape having a large diameter as it is arranged from the axial front end side to the rear end side, so that the screw shaft is sequentially pressed against the hole wall in the large diameter section. The amount of soil discharged to the ground can be greatly reduced.

  In addition, since the screw shaft is formed in a multistage shape that increases in diameter as it is arranged from the front end side to the rear end side in the axial direction, and the diameter of each step is constant, the soil pressed against the hole wall in each step The amount and pressure can be constant.

  Thereby, compared with the case where the conventional screw shaft is formed in the taper shape which becomes gradually large as it goes to the rear end side from the front end side, excavation resistance can be reduced. Accordingly, it is possible to reduce the amount of soil removal and to reliably prevent the occurrence of jamming and to appropriately drill and excavate the ground.

  Moreover, in the ground reinforcement method of this invention, while using said auger screw of this invention, while being able to acquire said effect, the hole wall is consolidated and the excavation hole which cannot fall easily can be formed. Thereby, the auger screw can be pulled out and the inside of the excavation hole can be held in an empty state, and ready mixed concrete can be injected and filled into the excavation hole.

  Therefore, according to the ground reinforcement construction method of the present invention, unlike the conventional ground reinforcement construction method, there is no possibility that it will not be solidified due to the soil or a large amount of industrial waste will be generated. Moreover, a short columnar body can also be formed easily. Furthermore, since the on-site training can be made unnecessary, the plant can be made unnecessary, and since excavation and injection can be performed in separate processes, the construction amount per day can be greatly increased.

It is a figure which shows the auger screw which concerns on one Embodiment of this invention. It is a figure which shows the ground reinforcement construction method which concerns on one Embodiment of this invention.

  Hereinafter, with reference to FIG.1 and FIG.2, the auger screw and the ground reinforcement construction method which concern on one Embodiment of this invention are demonstrated.

  Here, for example, the present embodiment relates to an auger screw and a ground reinforcement method suitable for use in forming a columnar body on a ground for constructing a small-scale building such as a house and performing reinforcement and improvement.

  Specifically, as shown in FIG. 1, the auger screw A of the present embodiment includes a drill bit 1 at the tip, and a screw shaft 2 that is rotatably supported around the axis O <b> 1, and an outer peripheral surface of the screw shaft 2. A screw provided in a spiral shape so as to integrally project outward from the screw shaft 2 and to be twisted backward in the forward rotation direction (direction rotated when drilling) as it goes from the front end side to the rear end side of the screw shaft 2 And a blade 3.

  Moreover, in the auger screw A of this embodiment, it is formed in the multistage shape which becomes large diameter, so that the screw shaft 2 is distribute | arranged from the front end side to the rear end side.

  That is, the screw shaft 2 of a predetermined length section (first section 2a) from the tip where the drilling bit 1 at the tip is provided is formed with the smallest diameter, and the first section 2a on the tip side is directed to the rear end side. The screw shaft 2 of the second section 2b having a predetermined length is formed with a larger diameter than the first section 2a.

  Furthermore, in the present embodiment, the third section 2c is provided, and the screw shaft 2 of the third section 2c is formed with a larger diameter than the second section 2b.

Furthermore, the screw shaft 2 of the present embodiment is gradually increased in diameter from the front end side of the large diameter side section to each connecting portion of the small diameter side section on the front end side adjacent to the direction of the axis O1 and the large diameter side section on the rear end side. Is formed with a tapered portion 2d that is small and is connected to the rear end side of the small-diameter side section.
In addition, what is necessary is just to set the taper angle of each taper part 2d suitably according to the soil quality of a drilling object ground, a drilling depth (auger screw length), an auger screw diameter, a set amount of soiling.

  The screw blade 3 provided in each section 2a, 2b, 2c (and each taper portion 2d) of the screw shaft 2 is formed so that the outer diameter thereof is the same from the excavation bit 1 at the tip to the third section 2c. Has been. Further, in the present embodiment, the excavation bid 1 is firmly supported by providing two screw blades 3 only on the tip end side and connecting the tips of the two screw blades 3.

  Further, the auger screw A of the present embodiment is formed so that the pitch d1 of the screw blade 3 is equal to or less than the outer diameter (outer diameter of the screw blade 3) d2 of the excavation bit 1.

  Furthermore, the screw shaft 2 (auger screw A) of the present embodiment is formed by detachably connecting a small diameter side section on the front end side and a large diameter side section on the rear end side adjacent to each other in the direction of the axis O1. .

  For example, a first screw shaft portion 2e having a minimum diameter, which is formed in a circular tube shape and is provided with a drill bit 1 at its front end and a screw blade 3 of a first section 2a on its outer periphery, extends from the front end to the rear end.

  And the 2nd screw shaft part 2f which provided the taper part 2d in the front-end | tip, was formed in the substantially cylindrical shape larger diameter than the 1st screw shaft part 2e, and the screw blade 3 of the 2nd area 2b was provided in the outer periphery. The first screw shaft portion 2e is inserted through the inside, and the rear end of the screw blade 3 of the first screw shaft portion 2e and the front end of the screw blade 3 of the second screw shaft portion 2f are connected.

  Further, a third screw shaft portion 2g having a tapered portion 2d at the tip and formed in a substantially circular tube having a diameter larger than that of the second screw shaft portion 2f and provided with a screw blade 3 of the third section 2c on the outer periphery, The first screw shaft portion 2e and the second screw shaft portion 2f are inserted through the inside, and the rear end of the screw blade 3 of the second screw shaft portion 2f and the tip of the screw blade 3 of the third screw shaft portion 2g are connected. Arranged.

  In the present embodiment, as described above, the auger screw A is configured to include the first to third screw shaft portions 2e, 2f, and 2g. Of course, the auger screw A may be configured, or the auger screw A may be configured by the first and second screw shaft portions 2e and 2f.

  In the auger screw A of the present embodiment having the above-described configuration, for example, the rear end is connected to an earth auger equipped with a speed reducer and a swivel, and the axis O1 direction is arranged at a predetermined position in the vertical direction. The auger is driven to rotate forward about the axis O1 and are sequentially lowered while excavating the ground with the excavation bit 1.

  As a result, the spiral screw blade 3 provided on the outer periphery of the auger screw A conveys the soil upward with the forward rotation and discharges it to the ground, and the ground is sequentially drilled and excavated.

  In the auger screw A of the present embodiment, the diameter of the screw shaft 2 is gradually increased from the first section 2a on the front end side to the third section 2c on the rear end side. . For this reason, the gap between the hole wall and the outer peripheral surface of the screw shaft 2 is reduced every time the first section 2a on the distal end side is sequentially transported from the second section 2b and the second section 2b to the third section 2c. The soil is sequentially conveyed from the adjacent small-diameter section on the front end side to the large-diameter section on the rear end side and pressed against the hole wall.

  Thereby, the hole wall is consolidated, and the hole wall can be prevented from collapsing, and the amount of soil removal can be reduced for drilling.

  Furthermore, in the auger screw A of the present embodiment, the diameter of the screw shaft 2 is gradually increased from the first section 2a on the front end side to the third section 2c on the rear end side, and the diameter is increased in each section 2a, 2b, 2c. Is made constant. For this reason, compared with the case where the conventional screw shaft is formed in a tapered shape in which the diameter gradually increases from the front end side toward the rear end side, the hole wall in each section (each step) 2a, 2b, 2c The amount of soil to be pressed and the pressure are almost constant. Thereby, excavation resistance decreases.

  Further, when the soil moves from the small-diameter side section to the large-diameter side section, the force that presses the soil against the hole wall increases toward the tip side of each section 2a, 2b, 2c. And in this embodiment, since the taper part 2d is provided in the front-end | tip and rear-end part of each area 2a, 2b, 2c which moves from this small diameter side area to a large diameter side area, each taper part 2d makes it a hole wall. The soil is smoothly moved from the small-diameter side section to the large-diameter side section while pressing the soil.

  In the present embodiment, the pitch d1 of the screw blade 3 is set to be equal to or smaller than the outer diameter of the excavation bit 1 (the outer diameter of the screw blade 1) d2. As a result, the discharging speed (moving speed) of the soil with respect to the rotational speed around the axis O <b> 1 becomes smaller than that of a general auger screw in which the pitch d <b> 1 of the screw blade 3 is larger than the outer diameter d <b> 2 of the excavation bit 1.

  As a result, the diameter of the screw shaft 2 is gradually increased from the first section 2a on the front end side to the third section 2c on the rear end side so that the diameter is constant in each section 2a, 2b, 2c. Even when the soil is moved from the small-diameter side section to the large-diameter side section, it is possible to prevent an excessive pressing force of the soil discharge from acting on the tip / rear end portions of the sections 2a, 2b, and 2c. .

  Therefore, if the ground is drilled and excavated using the auger screw A of the present embodiment, a suitable excavation hole is formed that reduces the amount of soil removal and the hole wall is compacted and hardly collapses.

  On the other hand, in the ground reinforcement method according to the present embodiment, as shown in FIG. 2, ready-mixed concrete (green concrete) is formed in the excavation hole 4 when the suitable excavation hole 4 is formed so that the hole wall is compacted and hardly collapses. 5 is input to form the columnar body 6.

  As a result, drilling and drilling while injecting cement milk from the tip of the auger screw as in the conventional method does not generate waste soil mixed with cement, unlike the method of forming soil cement pillars, so industrial waste is not generated. Significantly less (or disappear).

  Therefore, in the auger screw A of the present embodiment, the screw shaft 2 is formed in a multistage shape having a diameter that increases from the front end side to the rear end side in the direction of the axis O1, so When the excavated soil excavated by the excavating bit 1 at the tip is conveyed upward by the spiral screw blade 3, it is successively transferred to the large diameter section, pressed against the hole wall, and discharged to the ground. The amount of soil discharged can be greatly reduced.

  In addition, since the screw shaft 2 is formed in a multi-stage shape having a larger diameter as the screw shaft 2 is arranged from the front end side to the rear end side in the axis O1 direction, and the diameter of each step is formed constant, The amount of soil and pressure to be pressed can be made constant.

  Thereby, compared with the case where the conventional screw shaft is formed in the taper shape which becomes gradually large as it goes to the rear end side from the front end side, excavation resistance can be reduced. Therefore, it is possible to reliably prevent the occurrence of jamming and appropriately excavate the ground.

  In the auger screw A of the present embodiment, the connecting portion of the small diameter side section on the front end side and the large diameter side section on the rear end side adjacent to each other in the direction of the axis O1 of the screw shaft 2, that is, the step portion of each step. By providing the tapered portion 2d, even when the screw shaft 2 is formed in a multi-stage shape, the soil is smoothly conveyed from the small diameter side section on the adjacent front end side to the large diameter side section on the rear end side. It becomes possible to supply.

  Thereby, it can prevent that big excavation resistance generate | occur | produces in the level | step-difference part of each stage, and excavation resistance can be reduced reliably. That is, it is possible to more reliably suppress the occurrence of jamming and the like and to appropriately drill and excavate the ground.

  Further, since the tapered portion 2d is provided at the step portion of each step, when the soil passes through this tapered portion, the soil can be pressed against the hole wall with a large pressing force, and the soil can be effectively discharged. The amount of soil can be reduced.

  Further, in the auger screw A of the present embodiment, the pitch d1 of the screw blade 3 is set to be equal to or smaller than the outer diameter d2 of the excavation bit 1, thereby reducing the conveying speed of the soil upward relative to the rotational speed. Can do.

  Thereby, even if it is a case where it forms in the multistage shape which becomes large so that the screw shaft 2 may be arranged from the front end side to the rear end side in the axis O1 direction, the rear end side from the small diameter side section on the adjacent front end side. It is possible to prevent the excavation soil from rapidly moving to the large diameter side section and generating a large excavation resistance. That is, by setting the pitch d1 of the screw blade 3 to be equal to or less than the outer diameter of the excavation bit d2, the excavation resistance can be reduced more reliably, and the ground can be suitably excavated while suppressing occurrence of jamming. It becomes possible.

  Moreover, in the auger screw A of this embodiment, the small diameter side section of the adjacent front end side and the large diameter side section of the rear end side are configured to be separably connected to each other as necessary. The number of stages and the diameter of the screw shaft 2 and the screw blade 3 can be easily formed. In addition, since the screw shaft portions 2e, 2f, and 2g of each stage can be manufactured individually, it is possible to reduce the manufacturing cost.

  Moreover, in the ground reinforcement construction method of this embodiment, by using said auger screw A, a hole wall is consolidated and the excavation hole which cannot fall easily can be formed. Thereby, the auger screw A can be pulled out and the inside of the excavation hole 4 can be held in an empty state, and the ready mixed concrete 5 can be injected and filled into the excavation hole 4.

  Therefore, according to the ground reinforcement construction method of this embodiment, unlike the conventional ground reinforcement construction method, there is no possibility that it will not be solidified by the soil or a large amount of industrial waste will be generated. Moreover, the short columnar body 6 can also be formed easily. Furthermore, since the on-site training can be made unnecessary, the plant can be made unnecessary, and since excavation and injection can be performed in separate processes, the construction amount per day can be greatly increased.

  As mentioned above, although one embodiment of the auger screw and the ground reinforcement construction method concerning the present invention was described, the present invention is not limited to the above-mentioned one embodiment, and can be suitably changed in the range which does not deviate from the meaning.

DESCRIPTION OF SYMBOLS 1 Drilling bit 2 Screw shaft 2a 1st area 2b 2nd area 2c 3rd area 2d Taper part 2e 1st screw shaft part 2f 2nd screw shaft part 2g 3rd screw shaft part 3 Screw blade 4 Drilling hole 5 Ready mixed concrete ( Raw kon)
6 Column A Auger screw O1 axis

Claims (5)

A screw shaft provided with a drilling bit at the tip, and supported rotatably around the axis;
A screw blade provided in a spiral shape protruding integrally from the outer peripheral surface of the screw shaft to the outside and sequentially twisted toward the rear side in the positive rotation direction from the front end side in the axial direction toward the rear end side;
An auger screw characterized in that the screw shaft is formed in a multistage shape having a larger diameter as it is arranged from the axial front end side to the rear end side. The auger screw according to claim 1,
The screw shaft gradually decreases in diameter from the distal end side of the large diameter side section to each connecting portion of the small diameter side section on the distal end side adjacent to the axial direction and the large diameter side section on the rear end side. An auger screw formed with a tapered portion connected to the rear end side of the small diameter side section. In the auger screw according to claim 1 or 2,
An auger screw formed such that a pitch of the screw blade is equal to or less than an outer diameter of the excavation bit. In the auger screw as described in any one of Claims 1-3,
An auger screw formed by detachably connecting a small-diameter section on the front end side adjacent to the axial direction and a large-diameter section on the rear end side. A method of reinforcing a ground by forming a columnar body in the ground,
A ground reinforcement comprising drilling and excavating the ground using the auger screw according to any one of claims 1 to 4, and filling the excavated hole with ready-mixed concrete to form the columnar body. Construction method.

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