JP2709382B2 - An auger drill for drilling a spiral groove and a method of constructing a spiral groove on the peripheral wall of an underground hole with this auger drill. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for forming a spiral groove in an underground hall, and a method for drilling a spiral groove with the apparatus.
And an underground pile formed by a spiral groove, specifically, a spiral groove continuously formed on a peripheral wall of an underground hole for increasing the peripheral friction force in the bearing capacity of an embedded pile, and A device that increases the frictional force of the peripheral surface and at the same time enables economical construction, forms a spiral groove compacted in the ground when the auger drill rotates, a method of opening the spiral groove with this device, and a spiral groove It relates to an underground pile that can be formed.

[0002]

2. Description of the Related Art The present invention relates to a so-called SIP (Soil cement Injection) which is particularly frequently used in the conventional embedding pile method.
The present invention presupposes the preceded Pile method), but the conventional SIP method pierces a hole in the ground with an auger drill, injects cement paste into the bottom of this vertical pit, and then inserts the PC pile. It is inserted and lightly piled (flicked), and then a cement paste is poured between the pile and the pit wall to cure.

In the SIP method, the ground vibration and noise are significantly reduced as compared with the method of driving a pile from the beginning by excavating with an auger drill, so that damage to surrounding buildings is reduced and complaints of residents are also reduced. Among the existing pile embedding methods, it can be said that it is a stunning pile intrusion method that is no better than the ground construction method especially in the center of the city.

[0004] However, the peripheral wall of an underground hole (vertical shaft) drilled with an auger drill to apply the SIP method is uniform and monotonous as a whole. For this reason, even if it is constructed by the SIP method, it has been felt that there is a limit in increasing the peripheral frictional force of the pile.

[0005] Therefore, an apparatus or a method of forming a groove in a peripheral wall of an underground hole for increasing the peripheral frictional force of an embedded pile has been proposed from an early stage. For example, Japan Real Kaikai 52-32
904, JP-A-2-54019, JP-A-2-54019
213514 publication. The common feature of these prior arts is that a plurality of annular grooves are cut out at a predetermined height difference on the peripheral wall of a vertical shaft, a pile is inserted, and then cement paste is injected and cured.

[0006]

However, in the above-mentioned prior art method, the grooves are formed in the peripheral wall of the vertical shaft, because the gap between the grooves is large in the underground hole, so that the peripheral frictional force does not increase. In addition, due to the following construction difficulties, considerable research must accompany the practical application.

First, the device for opening the enlarged groove has an attached blade for forming the enlarged groove and an accessory device for opening and closing the blade, so that the structure is complicated, and there is a problem in production and operation. There is a fear that defects will occur during the opening of the grooves, and it is expensive and economically disadvantageous.

Secondly, the workability is poor because the work for opening the enlarged groove after drilling with an auger drill must be separately continued.

[0009] Third, the method of forming a perforated peripheral wall into a cut-out groove disturbs the original ground of an underground hole, which results in a loss of peripheral frictional force and chips (sediment). However, it piles on the bottom of the underground hole and has a bad influence on the bearing capacity of the pile tip.

Fourth, the individual grooves are turbid, which are positioned coaxially with an appropriate height difference, but are cured after being injected between the peripheral wall and the pile. Since the peripheral frictional force of the paste is only an extension that multiplies the circumferential surface area increase by the circumference, it cannot be said that the peripheral surface length is long and does not help separately from the increase in the peripheral surface frictional force.

Accordingly, an object of the present invention is to increase the peripheral frictional force of the cement paste injected and cured between the peripheral wall of the underground hole and the PC pile inserted into the underground hole, and consequently the periphery of the pile. By forming grooves that increase the surface friction force by solidifying the peripheral wall of the underground hole, the contour of the groove is clear, the generation of chips is also reduced, and less piles are collected in the underground hole, so that the supporting force at the tip of the pile does not decrease. Become.

It is another object of the present invention to provide a method for continuously forming a spiral groove by connecting the above grooves together.

It is still another object of the present invention to provide an underground pile in which the cement paste formed by the spiral groove has a peculiar irregular surface shape and has increased peripheral frictional force.

[0014]

In order to solve the above-mentioned problems, the present invention employs the following specific technical means.
The present invention provides an auger drill in which a groove tip for pressing a peripheral wall of an underground hole to form a groove on one outer surface of one of the outermost pits among pits arranged at the lower part of the tip of the auger drill is provided. .

According to the present invention, the ratio of the length to the diameter at the time of piercing the ground, that is, the lower end portion where the auger drill having a large slenderness ratio is the tip portion is placed on the ground, and the upper end portion is pressed down for excavation of the ground. The middle part of the auger drill bends due to complex factors such as centrifugal force and vibration due to the mechanical characteristics that apply the rotating force, and a large frictional resistance between the soil and the auger drill and spiral wing. Even if the drilling is performed to the size of (ds), the displacement amount (δ) is generated in the middle part of the auger drill as much as the margin for swing prevention fixedly installed on the main body, which corresponds to this degree. An additional oversize width (b) is additionally associated with the drilling diameter (d
The hole is pierced in the size of h).

"Study on bearing capacity of pile for SIP construction"
-Soil cement formed when drilling with an auger drill with a pile diameter of 100 mm, as revealed by Lee Myung-Hwan and one other person, Spring Geotechnical Conference 1993, jointly sponsored by the Korea Geotechnical Society and the Korean Architecture Society. Or, the thickness of the wall of the cement paste was examined to be 64-75 mm, and it was found that the thickness of the wall of the cement paste due to the surplus hole was about 25 mm except for a radius of 50 mm of the margin width.

Therefore, when a tip having a size within the extra width (b) is attached to the outer side surface of the pit at the tip of the auger drill during the drilling operation, the tip of the auger drill becomes one in the drilling operation. Since the drilling is started as soon as possible by contacting the ground and receiving the ground reaction force, even if a spiral groove whose diameter is enlarged by the radius of the tip larger than the drill diameter (ds) is formed, the intermediate portion of the subsequent auger drill is formed. Since the displacement amount (δ) forms the surplus width (b), the peripheral wall of the hole to be finally drilled is not formed with a spiral groove, but is drilled to the extent that the peripheral wall is solidified.

Here, the shape of the chip is a hemisphere, a semi-ellipse sphere, or a round shape having no similar corners, and the spherical surface is directed in the centrifugal direction. Is expressed as

On the other hand, the method of attaching the chip is welding to the outer side surface of the pit, or forming the hemisphere of the chip as a head of a normal screw nail, making a hole in the pit itself, and disassembling the chip by screw fastening. The pit has the same life as the pit so that it can be easily manufactured or used as a part of the pit in a manufacturing plant.

In consideration of this point, in the present invention, when drilling, the tip is limited to the excess digging width (b) of the radius of the tip and adheres. Therefore, at the time of drilling, the peripheral wall of the underground hole on the ground is not disturbed so that the auger drill is formed. When removing the underground hole, the surrounding wall of the underground hole becomes a space where the earth can be removed except for the excavated soil remaining on a part of the spiral wing, but the centrifugal force and vibration when the auger drill rotates and The auger drill has an eccentric angle (θ) with an eccentric angle (θ) as much as the marginal space within the swing prevention due to the rotational resistance that is almost negligible, and the pulling drive force that acts upward on the drive unit located at the upper end of the auger drill It comes to rotate.

Therefore, several meters to 10-20 to prevent swinging.
The side surface of the tip of the auger drill separated by about m, that is, the outer part of the pit to which the chip is attached, is pulled out simultaneously with rotation while being eccentric while continuously contacting the peripheral wall of the underground hole, and the hole diameter of the underground hole [ dh: spiral wing diameter of the auger drill (ds) + excavation width (b) × 2], a trace of the enlarged diameter (de) remains due to the turning radius larger by the radius of the tip. This mark is a kind of spiral groove formed by the action of compacting the chip as it passes.

Here, ds: diameter, b: excess width, dh:
Drilling diameter, δ: displacement amount, rt: tip radius, de: expanded diameter, θ: eccentric angle.

In other words, the spiral groove is not formed at the time of drilling, and the portion which becomes the peripheral wall is hardened, and the spiral groove of the size of the chip limited to the size of the extra hole at the time of drawing is continuously formed. Then, a part of the cement paste poured into the peripheral wall of the underground hole and the space around the PC pile is inserted into the spiral groove and is cured, whereby an underground pile having the peripheral surface shape of the spiral groove is formed.

The concrete portion thus solidified increases the peripheral frictional force against the peripheral wall of the underground hole, which is the same as indirectly increasing the peripheral frictional force between the pile and the peripheral wall. This results in increased support for the pile.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings made according to preferred embodiments.

FIG. 1 is a perspective view showing the tip of an auger drill 1 according to the present invention. The auger drill 1 has a spiral wing 2 on its peripheral surface, or one or more pits 3 are attached to the lower part of the tip of the spiral wing 2. Pit 3 is shown in detail in FIGS. In this figure, a cutting tip 4 is attached to the tip of each pit 3 and a groove tip 5 is attached to the outer surface.

Although the groove chip 5 is shown as hemispherical in the drawing, the present invention is not limited to this, but is not limited to this, and has a semi-elliptical spherical shape or a similar round shape without corners, and the spherical surface faces the centrifugal direction. Here, these are included and expressed as “hemispherical”. When the spiral blade 2 integrated with the auger drill 1 rotates, the groove 5 does not cut the peripheral wall of the underground hole, but extrudes the surrounding earth and sand, small stones, etc. through which the auger drill 1 passes in a radial direction and solidifies the groove. Open a groove in a non-reclaimed formula. According to these, the periphery of the groove is formed so as to be hardened to correspond to its volume.

The groove chip 5 reduces the amount of chips when drilling an underground hole, and is formed sharply and smoothly.
Then, the PC pile is inserted into the underground hole where the drilling and the drawing are completed, and the cement paste is poured into the space left between the underground hole and the PC pile, and the cement paste is cured before the cement paste is cured. Part flows into the groove,
Later, when it hardens, it becomes an anchor for the underground hall. This is P through the cement paste layer
This results in an increase in the peripheral bearing capacity for the C pile.

Any of the above-mentioned auxiliary tips 6 can be used as the cutting tips 4
Or the next higher strength special steel. As shown in FIG. 2, in addition to the case of using a general metal having a strength slightly lower than that of the cutting tip 4, as shown in FIG. 3, a special steel auxiliary tip 6 having a very high strength such as tungsten steel is used. It may be attached to the outer end surface of the chip 5.

In this case, the outer end face of the groove chip 5 must be processed into a flat surface so that the auxiliary chip 6 can be attached, or the back surface of the auxiliary chip 6 must be processed accordingly. If the cutting tip 4 and the auxiliary tip 6 are made of the same material, the working life is the same, so that it is convenient because the pit 3 can be temporarily worked when it is replaced.

The method of attaching the groove chip 5 to the pit 3 is a method of welding to the outer surface of the pit 3 and a method of forming a hole in the pit 3 in a form in which the hemisphere of the groove chip 5 is regarded as a normal screw head. A method of manufacturing the groove chip 5 so that it can be easily fixed and disassembled with a screw fastening method, a method of integrally manufacturing the pit 3 and the groove chip 5 at a manufacturing plant, and the like can be adopted. The attachment method is preferably welding.

FIG. 4 is a side view showing a case where an underground hole is drilled by the auger drill according to the present invention, and FIG. 5 illustrates the principle of the occurrence of overdig according to the displacement of the auger drill caused by vibration and driving force at the time of drilling. FIG. 6 is a cross-sectional view, and FIG. 6 is a detailed view of a portion A in FIG.

When drilling the ground, the lower end, which is the tip of the auger drill 1 fixed to the drive unit 9 fixed to the auger drill and capable of driving only in the vertical direction, is placed on the ground and the upper end is used for excavation of the ground. Therefore, since it is necessary to apply a pressing and rotating force from above, the drilling driving force 12 acts downward on the driving device 9 which is the upper end of the auger drill 1, and the lower surface which is in contact with the ground receives a ground contact with the ground. Force 1
1 acts upward to generate an amount of displacement δ in the swing preventing device 10 to the extent of a margin, and a surplus width b of a size corresponding to this extent.
Are additionally drilled with a size of the drilling diameter dh.

Therefore, when the groove tip 5 is attached to the side surface outside the pit 3 which is the tip of the auger drill 1 at the time of the drilling operation, the tip of the auger drill 1 is attached in the drilling process. Is the first contact with the ground and the ground reaction force 1
Therefore, even if a spiral groove 22 having a diameter larger than the drill diameter ds by the radius of the groove tip 5 is formed, a surplus digging width of about the displacement amount δ of the intermediate portion of the subsequent auger drill 1 is formed. (B) is formed, and the spiral groove 22 is not formed in the peripheral wall 21 of the underground hole to be finally drilled, and the drilling operation to harden the peripheral wall 21 is completed.

FIG. 7 is a side view of an underground hole illustrating an example of a spiral groove 22 formed when the auger drill is pulled out after drilling. FIG. 8 is a view showing centrifugal force and vibration when rotating when the auger drill is pulled out. FIG. 9 is a cross-sectional view illustrating the principle of forming the spiral groove of the tip by eccentric rotation of the tip of the auger drill, and FIG. 9 is a detailed view of a portion B in FIG.

According to the present invention, when drilling, the radius r
The size of t is limited within the extra width b, so that the peripheral wall 21 on the ground is not disturbed at the time of drilling, and when the auger drill 1 is pulled out, the earth and sand generated at the time of drilling by the rotation of the auger drill 1 is removed. The operation is continuously performed, and the peripheral wall 21 of the underground hole becomes a space in which the excavated earth and sand remaining on a part of the spiral wing 2 is removed to remove the soil, but when the auger drill 1 rotates. The auger drill 1 has an eccentric angle θ in a state where the auger drill 1 is slightly eccentric so as to have a marginal space width in the anti-swing device 10 due to the centrifugal force and vibration of the auger drill 1 and the rotational resistance which has become almost negligible. The drive unit 9 located at the upper end is rotated by the pull-out driving force 13 acting upward.

Therefore, several meters or one from the anti-swing device 10
The side surface of the tip of the auger drill 1 separated by about 0 to 20 m, that is, the outer portion of the pit 3 to which the groove chip 5 or the auxiliary chip 6 is attached, was eccentric while continuously contacting the peripheral wall 21 of the underground hole. It is pulled out simultaneously with the rotation to the state, and a trace of the expanded diameter de remains due to a rotation radius larger by the radius rt of the groove tip 5 than the underground drilling diameter dh.
The trace is a kind of spiral groove 22 formed by the action of compacting the groove chip 5 while operating.

Here, the depth of the spiral groove 22 is the size of the maximum groove chip 5, but there may be a slight difference depending on the type of ground, the degree of water content, and the like, and the drawing speed of the auger drill 1 is artificial. The pitch of the spiral groove 22 forms a single groove having a substantially regular shape as seen in FIGS. 12 and 13.

In other words, the spiral groove 22 is not formed at the time of drilling, and the portion forming the peripheral wall 21 is solidified. At the time of drawing, the radius rt of the groove chip 5 limited to the groove excess width b or less is set. Spiral grooves 22 are continuously formed,
Part of the cement paste poured into the space around the underground hole and the PC pile is inserted into the spiral groove 22 and cured, and an underground pile having the peripheral shape of the spiral groove 22 is formed.

FIG. 10 illustrates the peripheral wall 21 of the underground hole in which the spiral groove 22 is formed by the above method, and FIG. 11 is an enlarged view of a portion C in FIG. The spiral groove 22 is formed within the volume range of the groove chip 5 or the combination of the groove chip 5 and the auxiliary chip 6 on the underground peripheral wall 21, and the sectional area of the spiral groove 22 is pushed toward the peripheral wall. In other words, the peripheral wall on the side of the spiral groove (22) is hardened at high density with almost no chips.

In the above description, points to be noted when applying the groove chips (including the auxiliary chips) are listed as follows.

First, when the radius rt of the hemispherical groove tip 5 is larger than the surplus width b (rt> b), all the spiral grooves 22 are formed at the time of drilling and drawing, so that the spiral groove 22 is formed. The pitch is too tight, the spiral is irregular, or there is a fear of disturbing the already formed spiral groove.

The second is a method in which a groove is not formed at the time of excavation and a groove is formed only at the time of pulling out, and a method of forming a groove at the time of excavation and not forming a groove at the time of pulling out is sometimes supposed. In all three methods, the excavation equipment becomes complicated and the workability is deteriorated.

Third, the installation of the shaft on the center line of the spherical groove chip 5 so as to form the groove while the groove chip 5 automatically rotates also complicates or coarsens the equipment. I feel sorry.

Spherical groove chips, square groove chips and the like are not dealt with in the present invention because they are disadvantageous from the viewpoint of practicality, economy, workability, and technology in comparison with the hemispherical groove chips 5.

The following points were confirmed as a result of testing the underground pile constructed after test drilling the underground hole at the site using the auger drill of the present invention.

1. Test conditions Ground condition: landfill layer and weathered soil layer and weathered rock layer mainly composed of silty sand Pile type: 400mm diameter PC pile Drilling diameter: pile diameter + 100mm (total diameter 500mm) Drilling depth: 9m Pile length : Approximately 9m Loading test device: Pile Driving Analysis
zer (PDA) -Model PAK, Serial
No. 1218 (Pile Dynamics Inc., USA) Groove tip: hemispherical with a radius of 35 mm

Here, in order to make the radius rt of the groove tip 5 within 25 mm, which was investigated as the maximum surplus hole width, in the case of the used drilling equipment, the pit is compared with the side portion of the spiral blade 2 in the auger drill 1. Considering that the wear on the side surface of the pit 3 is more severe, the expected average wear thickness of the pit side surface (10 mm) is set at the radius of the groove 5 (rt: the same as the remaining width 25 mm).
And the actual groove tip radius was planned to be 35 mm.

2. Test results (1) Shape of perforated surface according to the conventional method and the present invention The peripheral wall of the underground hole of the conventional method is monotonous, while the peripheral wall of the underground hole drilled by the method of the present invention has almost a constant spiral groove. A smooth state was formed at a pitch of.

That is, the underground hole constructed by the conventional method had a monotonically measured diameter of about 160 cm, whereas the underground hole according to the present invention had a spiral groove 22 as shown in FIGS. The projected radius of the formed and measured groove 22 was about 2.2 cm, the pitch was about 13 cm, and the enlarged diameter of the projected portion was about 167 cm, confirming a completely different point from the underground hole by the conventional method.

(2) Results of load test of piles constructed according to the conventional method and the present invention The results of the load tests were divided into peripheral friction force and tip support force, and the support force was compared under the same ground conditions. According to the report, PC was installed in the underground
When the pile was inserted and the cement paste was poured and cured, the peripheral frictional force was increased by about 40-50%, and the overall supporting force was increased by about 20-30%.

[0052]

According to the present invention, the following effects can be obtained based on the above configuration. (1) The present invention mainly focuses on forming a spiral groove in the process of pulling out an auger drill after drilling in the peripheral wall of an underground hole, inserting a PC pile, driving in cement paste, and curing. The increased bearing capacity contributes to the improvement of construction quality, and in order to obtain the same required bearing capacity, the pile length can be reduced under the same conditions to save costs.

(2) If a groove having a simple structure is attached to the outer surface of the pit, the diameter can be naturally expanded when the material is pulled out after the drilling operation, so that additional expanding equipment and additional expanding operation are not required. Good workability and economical construction are possible.

(3) When forming a spiral groove The groove is formed by a so-called non-abrasion type in which the groove is naturally extruded in the centrifugal direction and solidified. The ground around the inner wall of the underground hall is not scraped, and it is spirally drilled without generating any chips without damaging it.Therefore, there is no need for subsequent work to remove the chips separately. There is no risk of chips being piled up on the bottom, so there is no reduction in the bearing capacity of the pile tip. In addition, since the ground in the groove is made firm, the frictional force on the peripheral surface is greatly increased.

(4) The ground chips are hemispherical with no corners, and the ground mixed with pebbles and gravel is also compacted, so that the problem of pebbles and gravel coming out and accumulating on the bottom of the underground hole is remarkable. Be improved.

(5) By forming one spiral groove in which the groove is entirely continuous, the peripheral friction force against the enlarged wall between the peripheral wall of the underground hole and the hardened cement paste is reduced by the diameter and the spiral groove. Diagonal distance of the interval, ie, the width of the increase in the surface area by expanding the diameter to the length of the square root is greatly increased.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of an auger drill used in the present invention.

FIG. 2 is a perspective view of a pit according to an embodiment of the present invention.

FIG. 3 is a perspective view of a pit according to another embodiment of the present invention.

FIG. 4 is a side view of an underground hole drilled by the auger drill of the present invention.

FIG. 5 is a cross-sectional view illustrating the principle of the occurrence of extra excavation accompanying displacement of the auger drill due to the action of vibration and driving force during drilling.

FIG. 6 is a detailed view of a part A in FIG. 4;

FIG. 7 is a side view of an underground hole exemplifying a form in which a spiral groove is formed when an auger drill is pulled out after drilling.

FIG. 8 is a cross-sectional view illustrating the principle of forming a spiral groove of a tip due to eccentric rotation of the tip of the auger drill due to centrifugal force and vibration when rotating when the auger drill is pulled out.

FIG. 9 is a detailed view of a portion B in FIG. 7;

FIG. 10 is a cross-sectional view of a peripheral wall which has been completely drilled with an auger drill.

FIG. 11 is a detailed view of a portion C in FIG. 10;

FIG. 12 is an actual photograph of an underground hole drilled by an auger drill having a tip.

FIG. 13 is a partially enlarged photograph of the underground pile obtained in the underground hall of FIG.

[Explanation of symbols]

1 Auger drill 2 Spiral wing 3 Pit 4 Cutting tip 5 Groove tip 6 Auxiliary tip 11 Ground reaction force 12 Drilling drive force 13 Pulling drive force 21 ‥‥ Surrounding wall 22 ‥‥ Helix b ‥‥ Excavation width de ・ ・ ・ ・ Diameter of hole expansion dh ・ ・ ・ ・ Diameter of drill hole ds ・ ・ ・ ・ Diameter of drill rt ・ ・ ・ ・ ・ ・ Diameter of groove δ ・ ・ ・・ Displacement θ ・ ・ ・ ・ Eccentric angle

Claims (2)

(57) [Claims] 1. An auger drill 1 for inserting a PC pile.
In the case of drilling an underground hole having a diameter dh (ds <dh) by the drill diameter ds of the spiral blade 2 of the above, several pits 3 are integrated with the tip of the lower spiral blade 2 of the auger drill 1. And a hemispherical groove chip 5 or a groove chip 5 having a radius rt almost the same size as the surplus width [b = (dh−ds) / 2] on the outer surface of one pit 3. In the process of attaching the tip 6 and drilling a hole together with the rotation of the rotating shaft of the auger drill 1, the spiral is used to naturally press the peripheral wall in the centrifugal direction by the groove tip 5 or the groove tip 5 and the auxiliary tip 6. The groove 22 is hardly formed, and in the process of pulling out the rotary shaft, the groove tip 5 or the groove tip 5 and the auxiliary tip 6 are pulled out while holding the eccentric angle θ by centrifugal force and vibration when the auger drill 1 rotates. Auger drill, characterized in that the helical groove 22 of Hikezu Narushiki peripheral wall 21 of the underground hole is formed. 2. A semi-elliptical shape having the same or the next tip radius (rt) as an extra excavation width [b = (dh-ds) / 2] on an outer surface of a pit which looks at a peripheral wall side of an underground hole. In the process of drilling an underground hole with an auger drill with a groove tip attached, the above-mentioned groove tip naturally extrudes and solidifies the peripheral wall in the centrifugal direction, so that the groove is not formed as much as possible, and at a constant speed in the process of pulling out the auger drill The centrifugal force and vibration caused by the rotation of the auger drill are used to increase the radius of rotation of the groove tip so that a non-cutting spiral with a predetermined pitch is formed on the peripheral wall of the underground hole. A method of constructing a spiral groove to be hardened in the underground hall to make.