JP2015183395A - Construction method of piles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute piles capable of securing high bearing power, by being supported by its support layer, by forming the support layer capable of securing proper bearing power at a proper depth position of the weak ground.SOLUTION: A process of erecting excavation compaction means 3 at a required position of the ground (g), a ground excavation process of excavating up to the design depth by driving the excavation compaction means 3 for excavation while applying an excavation load by rotational driving means, a pull-up process of pulling up while reversely rotating the excavation compaction means 3, a support layer forming process of firming a support layer 4 capable of securing bearing power of design bearing power or more by compacting excavation sediment in an excavation hole 2 up to the design depth by applying a descent load while reversely rotatingly driving the excavation compaction means 3 and a crushed stone pile forming process of repeating a cycle of compacting this crushed stone thereby up to an upper end opening part of the excavation hole 2 while reversely rotating an excavation blade 3b of the excavation compaction means 3 by inputting the crushed stone in the excavation hole 2, are executed in this order.

Description

  The present invention relates to a method for constructing piles for reinforcing a ground for a soft building or a site for a building.

There are several proposal examples regarding construction methods and tools for piles that reinforce soft ground.
Patent document 1 is an example, and relates to a pile used for various civil engineering or construction work. This is a spiral drilling blade arranged at the lower part of a pile body formed with a tip at the tip, and from the drilling blade around the upper part. It has a narrow pitching blade.

  According to the pile of this patent document 1, when this is screwed into the ground with the rotation drive means, it is possible to dig well into the ground by the action of the spiral excavation blade, and simultaneously with the burying of the pile in the ground It is said that the generated excavated earth and sand can be backfilled by the action of the filling blade.

  Patent Document 2 relates to a foundation pile and a method for installing the foundation pile, in which a spiral excavation blade is configured continuously or intermittently from the lower end to the upper end on the outer periphery of a pile body made of a vertically long steel pipe. In addition, the diameter of the excavating blade is configured to gradually increase toward the upper end.

  In addition, the foundation pile of Patent Document 2 is screwed into the ground with a rotational drive means, and is built by rooting when the lower end reaches the support ground. It is said that the excavating blade can act as an anchor when the excavating blade bites into the ground, and a sufficient supporting force can be obtained by the frictional force.

Patent Document 3 relates to a screwed steel pipe pile,
In screwed steel pipe piles embedded in the ground by screwing using wings attached to steel pipes,
The blade is attached to the outer peripheral surface in the vicinity of the tip of the steel pipe pile in a spiral manner by attaching a fan-shaped steel plate obtained by dividing a doughnut-shaped steel plate whose outer diameter is larger than the outer diameter of the steel pipe, or the tip of the steel pipe pile A lower wing attached to the same height position of the outer peripheral surface near the section in the same direction and inclined at the same angle;
A steel plate having a structure similar to the steel plate of the lower wing is attached to the outer peripheral surface in the vicinity of the intermediate portion in the longitudinal direction of the steel pipe pile in a spiral manner in the same direction as the lower wing, or the intermediate in the longitudinal direction of the steel pipe pile It is a screwed-type steel pipe pile comprised by the upper stage blade | wing inclined and attached to the same height position of the outer peripheral surface of the part at the same direction and the same angle as the said lower stage blade.

  Therefore, according to the screwed steel pipe pile of Patent Document 3, it is possible to mount the upper wing and the lower wing at a low cost, and according to this, even when the ground is screwed into the ground, the lower wing It is possible to intrude at a pitch close to the pitch determined from the dimensional shape of the upper wing, and the periphery of this pile body is not disturbed by the wing, so that it is possible to ensure a large vertical support force.

Patent document 4 relates to a steel pipe pile and a ground reinforcement method using the same, and among them, a ground reinforcement method using a steel pipe pile is:
The excavation having a spiral excavation blade on the outer periphery of a lower end of a steel tube, and compressing the outer periphery in the vicinity of the upper end of the tube downward without moving the earth and sand below the tube. It is a ground reinforcement method using a steel pipe pile embedded in a screwed type, comprising a compacted wing configured in a spiral shape opposite to the wing,
The steel pipe pile is made to stand upright at a required position on the ground and is driven to rotate forward, and the steel pipe pile is driven into the ground by excavating the excavation blade of the steel pipe pile,
From the time when the lowermost part of the consolidated wing of the steel pipe pile reaches the upper surface of the ground, a compressive load is applied to the steel pipe pile in addition to the forward rotation drive, and the steel pipe pile is further lowered until its lower end reaches the design depth. In addition to burying the steel pipe pile, the ground is reinforced by consolidating the earth and sand excavated by the excavating blade and pushed up by the excavating blade.

  According to the ground reinforcement method using steel pipe piles of Patent Document 4, the support capacity of the pile is further enhanced by consolidating and compacting the excavated soil around the pile disturbed by the excavating blade with the upper compacting blade. It is what.

Patent Document 5 relates to a steel pipe pile and a ground reinforcement method using the steel pipe pile.
A steel pipe pile consisting of a steel pipe that is press-fitted into the ground by non-rotating impact or vibration pressurization, with the lower part of the ground facing downward on the outer periphery near the upper end of the pipe. A doughnut-shaped flat compacted wing body disposed in a plane perpendicular to the longitudinal direction of the tubular body, and a skirt plate suspended from the outer periphery thereof. Two compacting blades are arranged, and a plurality of rib-like members for increasing the friction surface which are long in the longitudinal direction of the tubular body are arranged on the outer periphery of the lower part.

Among them, the ground reinforcement method using steel pipe piles is
The above steel pipe pile is made upright at a required position on the ground, and a non-rotating pressure is applied to the upper end of the steel pipe pile by striking or vibration pressurization, and the steel pipe pile is press-fitted into the ground, and the steel pipe pile is From the point when the compacted wing reaches the upper surface of the ground, the steel pipe pile is subjected to a greater non-rotating impact or vibration pressure, and the steel pipe pile is lowered until its lower end reaches the design depth. In this method, the steel pipe pile is buried, and the ground is reinforced by consolidating a portion of the ground located below the consolidation wing.

  According to the steel pipe pile of this patent document 5 and the ground reinforcement method using the same, the surrounding area of the steel pipe pile in the ground is consolidated by the upper compaction blade and compacted to further enhance the bearing capacity of the pile. It is what.

Patent Document 6 relates to an attachment for forming a crushed stone pile and a crushed stone pile forming apparatus including the attachment.
The former is an attachment for forming a crushed stone pile that is inserted into the ground while rotating to form a space and forms a crushed stone pile in the space while rising from the ground,
A cylindrical portion in which a crushed stone injection hole, which is at least one long hole having a long axis in the central axis direction, is formed on a side surface;
An open / close lid that closes the crushed stone injection hole from the outside of the cylindrical portion;
With
The opening / closing lid is an attachment configured to apply a force in a direction of closing the crushed stone introduction hole from the ground by rotation of the cylindrical portion when inserted into the ground.
The latter is a crushed stone pile forming device that forms a crushed stone pile containing crushed stone in the ground,
With the above attachment,
A driving device for driving the attachment by generating a rotational driving force in a forward direction and a reverse direction;
Is a crushed stone pile forming apparatus.

  According to the crushed stone pile forming apparatus provided with the attachment of Patent Document 6, the space for forming the crushed stone pile is excavated and formed in a predetermined ground while rotating it forward, and then turned into the ground while being inverted. The crushed stone is thrown into the bottom of the space and raised while being compacted by the attachment, and this is repeated up to the top of the space to form a crushed stone pile in the space.

Patent Document 7 relates to a tool for forming no-debris crushed stone pile,
A rotating shaft with a spiral drilling blade at the lower end;
A cylindrical casing that surrounds the upper part of the rotary blade excavating blade, and a casing in which two rows of crushed stone inlet ports formed of a plurality of openable inlet ports along the length direction are formed on the peripheral side wall;
Opening and closing means for opening and closing the lower end of the casing;
A rotation transmission means for transmitting a rotational driving force of forward rotation or reverse rotation to the rotating shaft and the casing as required;
It is a no-debris crushed stone pile forming tool.

  According to the non-extruded crushed stone pile forming tool of Patent Document 7, a drilling hole for forming a crushed stone pile on a predetermined ground can be formed by connecting this to the rotation driving means and driving it in the normal direction. However, at this time, the crushed stone pile is formed by pressing the excavated earth and sand against the inner wall of the excavation hole so as not to discharge the soil and consolidating the ground in the radial direction of the excavation hole. It is possible to increase the lateral support force. After completion of the formation of the excavation hole, it is raised while rotating in reverse, the crushed stone introduced from the crushed stone inlet is discharged into the excavation hole from the bottom, and the crushed stone is further compacted with the excavating blade from above, A crushed stone pile is formed by repeating this up to the top of the excavation hole.

Patent Document 8 relates to a method for forming a crushed stone pile and a crushed stone pile forming apparatus used for the method,
A pilot hole creating step of digging the target position of the target ground to the design depth to form a drilling pilot hole;
A cylindrical casing having a diameter larger than the pilot hole, a crushed stone inlet at the peripheral side, and a crushed stone inlet at the lower end, respectively, is provided on the excavation pilot hole formed at the target position of the target ground. A casing installation process to be placed upright;
With the crushed stone inlet at the lower end of the cylindrical casing closed, a continuous impact pressure or vibration pressure is applied to the ground around the excavation pilot hole through the cylindrical casing, A casing press-fitting step of press-fitting the cylindrical casing to a design depth while causing a liquefaction phenomenon in the ground;
Pull up the cylindrical casing by a height corresponding to the amount of crushed stone input for one time, open the crushed stone inlet at the lower end, and then use the crushed stone inlet on the peripheral side of the cylindrical casing to Insert the crushed stone, put the crushed stone into the hole for the pile generated below from the crushed stone inlet at the lower end, and then close the crushed stone inlet at the lower end, and then for the pile through the cylindrical casing Applying continuous impact pressure or vibration pressure to the crushed stone thrown into the hole, further liquefying the surrounding ground, compacting the thrown crushed stone, and when the compaction is completed, one batch Repeat the cycle from lifting of the cylindrical casing by a height corresponding to the amount of crushed stone input to completion of compaction of the input crushed stone until the entire range in the height direction of the pile hole is completed. The consolidation process;
After that, the embedding process of embedding on the surrounding ground submerged by the liquefaction phenomenon,
Is a method for forming crushed stone piles.

  Therefore, according to the method for forming a crushed stone pile in Patent Document 8, the ground around the hole for the pile is caused to liquefy in the process of forming the hole for the pile, and then the crushed stone is put into the hole for the pile. Even in the process of charging and compacting this to form a crushed stone pile, the support force of the crushed stone pile to be formed is further increased by creating a liquefaction phenomenon around it and further compacting it. be able to.

  As described above, according to Patent Documents 1 to 8, for steel pipe piles or crushed stone piles, in the case of the former, a high supporting force exceeding a mere frictional force can be ensured by a helical member or the like configured around the piles. In the case where both the front and rear persons are applied, the surrounding ground is compacted by some means to increase the supporting force. According to Patent Documents 1 to 8, when the lower end of the pile reaches the support layer, expect the support force by the support layer, otherwise, expect the frictional force, and in the latter case In order to obtain the necessary supporting force, it should be said that more piles are required as compared with the case where the supporting layer is reached.

Japanese Patent Publication No. 05-42524 JP 63-161219 A Japanese Patent Laid-Open No. 11-21885 Japanese Patent No. 4819179 Japanese Patent No. 5039229 Japanese Patent No. 4445033 Japanese Patent No. 4849580 Japanese Patent No. 5027958

  The present invention, unlike the techniques disclosed in Patent Documents 1 to 8 regarding the reinforcement of soft ground, ensures the supporting force required by design within the depth range in which the construction of the pile can be performed relatively easily. When a support layer that can be formed is not found, a support layer that can secure a support force corresponding to an appropriate depth position within the depth range of the ground is formed, and various piles supported by the support layer are constructed. It is an object of the present invention to provide a method for constructing piles that can constitute piles that can secure a high bearing capacity.

1 of the present invention excavates the ground in the vertical direction, consolidates the excavated earth and sand in the resulting excavation hole, and forms a support layer that can ensure a support force higher than the design support force in the ground at the design depth,
This is a method for constructing piles in which piles having a lower part supported by the support layer are disposed.

2 of this invention is the construction method of the piles of 1 of this invention,
A support layer forming material containing gravel or crushed stone is added to the excavated soil before or during consolidation, and the support layer forming material is compacted from the top of the support layer forming material to a design depth, and is supported in the ground at the design depth. A support layer capable of securing a supporting force exceeding the force is formed.

3 of the present invention is the construction method of the piles 1 or 2 of the present invention,
As the piles, crushed stone piles, steel pipe piles, concrete piles, or cement-based piles created on site are adopted.

4 of the present invention is an installation process of excavation compaction means for standing upright excavation compaction means composed of a steel pipe with a spiral excavation blade attached to the lower end at a required position of the ground;
A ground excavation step of excavating the steel pipe of the excavation compaction means to a required depth by driving forward rotation while applying a load for excavation by the rotation drive means;
A step of lifting the excavation compaction means for pulling up the excavation compaction means while driving the excavation blade in reverse rotation;
A predetermined descending load is applied while rotating the steel pipe of the excavation compaction means in a reverse rotation or without rotation, and the excavated sediment in the excavation hole or the excavated sediment and the crushed stone thrown thereon are the excavated blades at the bottom of the steel pipe And a support layer forming step of forming a support layer that can be consolidated to the design depth at the lower end of the steel pipe to ensure a support force equal to or greater than the design support force;
The excavation compaction means is pulled up by a height corresponding to the amount of crushed stone input, and the amount of crushed stone is charged into the gap between the peripheral side of the steel pipe and the inner periphery of the drilling hole. While reversely rotating the compaction means, the crushed stone is further introduced to the lower side of the excavation hole through the gap between the spiral excavation blades, and then the crushed stone is reversely rotated by the excavation blade of the excavation compaction means or In a non-rotating state, a crushed stone pile forming step of repeating a compaction cycle to be consolidated at the lower end of the excavation blade and the lower end of the steel pipe until reaching the upper end opening of the excavation hole,
Is a construction method for crushed stone piles.

5 of the present invention is a steel pipe installation step for erecting excavation compaction means consisting of a steel pipe having a spiral excavation blade attached to the lower end at a required position of the ground;
A ground excavation step of excavating the steel pipe of the excavation compaction means to a required depth by driving forward rotation while applying a load for excavation by the rotation drive means;
A step of lifting the excavation compaction means for pulling up the excavation compaction means while driving the excavation blade in reverse rotation;
A predetermined descending load is applied while rotating the steel pipe of the excavation compaction means in a reverse rotation or without rotation, and the excavated sediment in the excavation hole or the excavated sediment and the crushed stone thrown thereon are the excavated blades at the bottom of the steel pipe And a support layer forming step of forming a support layer that can be consolidated to the design depth at the lower end of the steel pipe to ensure a support force equal to or greater than the design support force;
A re-pumping step of the excavation compaction means for pulling up the excavation compaction means;
A steel pipe pile is inserted into the excavation hole, and a lower end of the steel pipe pile is press-embedded (incorporated) into the support layer;
It is a construction method of the steel pipe pile that executes in that order.

  According to the construction method of piles of the present invention 1, in the ground for construction such as a building, when there is no support layer that can secure a support force higher than the design support force in the ground at the design depth, By excavating a predetermined position of the ground in the vertical direction and consolidating the excavated sediment generated in the excavation hole to the design depth, a support layer that can secure a support force exceeding the design support force is formed in the ground at the design depth. By providing piles such as steel pipe piles, crushed stone piles, concrete piles, or cement-based on-site created piles by supporting the lower end of this support layer, sufficiently high bearing capacity can be secured even in soft ground. It is what I did.

  The means for excavating the ground in the vertical direction is not limited to a specific one as long as it can form an excavation hole with a design depth. For example, a steel pipe or the like having a spiral excavation blade fixed to the outer periphery of the lower end or a long excavation spiral member can be employed. Thus, the vertical excavation can be performed by various means. The means for compacting the excavated sediment in the excavation hole is not limited to a specific one as long as the excavated sediment can be compacted to the design depth. For example, the steel pipe or the like having a spiral excavation blade disposed on the outer periphery of the lower end is adopted, and this is placed upright on the excavation earth and sand of the excavation hole and rotated in the opposite direction to the excavation rotation, It is also possible to consolidate with the excavating blade rotating in the reverse direction.

  When the compaction is performed to the design depth, if the compaction means does not descend even if the compaction is performed with a load equal to or greater than the design support force, it can be easily determined that a support layer capable of ensuring the design support force has been formed.

  According to the construction method of piles 2 of the present invention, it is expected that a support layer capable of securing a supporting force exceeding the design supporting force even if the ground is extremely soft and the excavated soil in the excavation hole is consolidated to the design depth is expected. If not, add gravel, crushed stone, or similar support layer forming material on the excavated soil at an appropriate consolidation stage before consolidation starts or after consolidation starts, and then consolidated to the design depth from above. If the support layer that can actually secure the design bearing capacity cannot be formed after being consolidated to the design depth, the top of the consolidated excavated sediment (incomplete support layer) By adding additional support layer forming materials such as crushed stone and gravel to the top) and then re-consolidating from the top to the design depth, a support layer that can reliably secure a support force that exceeds the design support force is formed. can do. In addition, as described above, this support layer can be formed by a very simple process.

  According to the construction method of the piles of 3 of the present invention, various piles such as a crushed stone pile, a steel pipe pile, a concrete pile or a cement-based pile created with a lower end supported by a support layer capable of securing a design support force can be easily obtained. And it can be reliably constructed.

  According to the construction method of the crushed stone pile of 4 of this invention, the crushed stone pile which supported the lower end with the support layer which can ensure design support force can be formed easily.

  According to the construction method of the steel pipe pile of 5 of this invention, the steel pipe pile which supported the lower end with the support layer which can ensure design support force (rooting) can be constructed easily.

(a) is a cross-sectional explanatory view showing a state in which the excavation compaction means having the excavation blades at the lower end is brought upright at a predetermined position of the ground, (b) is a cross-sectional explanatory view showing a state where the ground is slightly dug down by the excavation compaction means (C) is a partially cutaway cross-sectional explanatory view showing a state where the ground is dug down to the design depth by excavation consolidation means. (d) is a partially cutaway cross-sectional explanatory view showing a state in which the excavation blade of the excavation compaction means is placed on the upper surface of the excavated soil in the excavation hole, and (e) is excavated by rotating the excavation compaction means in the direction opposite to that during excavation. Partial cutaway explanatory drawing which shows the state which has consolidated the excavated earth and sand in a hole to the middle. Partial cutaway explanatory drawing which shows the state which formed the support layer which can be consolidated to the design depth by excavation compaction means and can ensure the support force more than a design support force. (a) is a partially cutaway cross-sectional explanatory view of a drilling hole in which a support layer is formed, showing a state in which an amount of crushed stone suitable for the first stage consolidation treatment has been added, and (b) is a reverse rotation of the crushed stone by excavating and compacting means FIG. 6 is a partially cutaway cross-sectional explanatory view showing a state of being compacted. (c) is a partially cutaway cross-sectional explanatory view of the excavation hole forming the support layer, showing a state in which an amount of crushed stone suitable for the second stage consolidation treatment has been thrown in, and (b) is a crushed stone thrown into the second stage. FIG. 6 is a partially cutaway cross-sectional explanatory view showing a state in which the excavation consolidation means is reversely rotated for consolidation. (e) is a partially cutaway cross-sectional explanatory view showing a state in which the crushed stone charged up to the final stage is consolidated by reversely rotating the excavation compaction means, and (f) is an upper surface of the crushed stone that has been charged up to the final stage and has been consolidated and lowered. FIG. 3 is a partially cutaway cross-sectional explanatory view showing a state where the crushed stone is further added to the slab and a compaction plate is placed thereon and further compacted. Partial cutaway explanatory drawing which shows the state where the crushed stone pile was completed. (a) is a partially cutaway cross-sectional explanatory view showing a state where a steel pipe pile is inserted into the uppermost portion of the excavation hole in which the support layer is formed, and (b) is a state where the lower end of the steel pipe pile is lowered until it is press-fitted into the support layer. FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the invention will be described in detail based on examples and with reference to the accompanying drawings.

<Example 1>
The pile construction method of Example 1 is applied to formation of a crushed stone pile. The first stage is a drilling hole drilling process for drilling a drilling hole 2 in the target ground, and the second stage is drilling. The support layer forming step of forming the support layer 4 in the ground at the design depth by consolidating the excavated earth and sand 2a in the established excavation hole 2, and the third stage is supported by filling and consolidating the crushed stone 2b in the excavation hole 2 It is a formation process of the crushed stone pile which forms the crushed stone pile 1 supported by the layer 4, and implements the construction method of the crushed stone pile as a whole.

  In the first embodiment, as shown in FIGS. 1 to 6, the excavation and compacting means 3 is used for drilling the excavation hole 2 that forms the crushed stone pile 1 and for compacting the crushed stone 2 b introduced into the excavation hole 2. Is used. This excavation compaction means 3 is shown in FIGS. 1 (a) to (c), FIG. 2 (d), (e), FIG. 3, FIG. 4 (a), (b), FIG. 5 (c), (d) and As shown in FIGS. 6 (e) and (f), a steel pipe 3a and a spiral excavation blade 3b fixed to the outer periphery of the lower end thereof, and a plurality of spiral shapes fixed at regular intervals in the height direction of the steel pipe 3a. The guide blades 3c, 3c,. The excavating blade 3b has an excavating blade 3bb at the lowermost end. The guide blades 3c, 3c,... Are spiral blades formed in the same direction at substantially the same pitch as the excavation blades 3b. Each lower end side and upper end side are slightly smaller in diameter than the excavation blades 3b, and each is near the center. It is gradually enlarged toward the center and is configured to have the same diameter as the excavating blade 3b in the vicinity of the center. In the first embodiment, the diameters of the guide blades 3c, 3c,... Are configured as described above, but the whole may be configured to have the same diameter as the excavating blade 3b. Or you may employ | adopt the structure of another diameter aspect. The guide blades 3c, 3c,... Of the first embodiment further constitute a compact piece 3d that stands upright along its outer edge. Further, in the first embodiment, the lower end of the steel pipe 3a is closed, and the steel pipe 3a has a pointed end that is pointed downward.

  However, in the first embodiment, when the ground g such as a building site is weak, this is executed. In the first step of drilling the excavation hole, the ground g is placed at a target position. As shown in FIG. 1 (a), the excavation compaction means 3 is placed in an upright state, and then a steel pipe of the excavation compaction means 3 is applied while applying a slight load using a rotary drive device (not shown) such as an earth auger. 3a is driven to rotate forward (excavation rotation), and as shown in FIGS. 1 (a) and 1 (b), the excavation blade 3b is screwed into the ground g for excavation.

  The rotary drive device is connected to the upper end of the steel pipe 3a of the excavating and compacting means 3 and attached to a leader supported by an appropriate construction machine so as to be movable up and down.

  The excavation by the excavation consolidation means 3 is naturally performed up to the design depth as shown in FIG. The excavation by the excavation compaction means 3 is performed by the excavation blade 3b as described above. At this time, a plurality of guide vanes 3c, 3c,. By the consolidation piece 3d fixed to the outer edge of the drilling hole 2, the inner peripheral surface of the excavation hole 2 is slightly consolidated together with a part of the excavation earth and sand 2a generated inside, and is reinforced so as not to easily collapse. Further, the excavated earth and sand 2a in the excavation hole 2 is further excavated by the guide blades 3c, 3c,... There is no.

  The excavation compaction means 3 thus dug down to the design depth is then pulled up above the upper end opening of the excavation hole 2 while rotating in reverse. Naturally, this reverse rotation is performed by reversely driving the rotary drive means having a drive shaft coupled to the upper end of the steel pipe 3a. The reverse rotation is a rotation in the direction opposite to the excavation direction, and is intended to prevent the excavation soil 2a from being pulled up by the excavation blade 3b and the guide blades 3c, 3c,. It is. At this time, the inner peripheral surface of the excavation hole 2 is again slightly consolidated by the consolidation pieces 3d fixed to the outer edges of the plurality of guide blades 3c, 3c... So that they are not easily collapsed. .

  Further, during the excavation by the excavation compaction means 3, particularly when starting excavation, the excavated earth and sand 2a may be discharged onto the ground g from the vicinity of the upper opening of the excavation hole 2. Such excavated earth and sand 2a Backfill in 2. If necessary, the excavation compaction means 3 is pulled up so that the excavated sediment 2a is backfilled in the excavation hole 2.

  In the above, in the process of drilling the excavation hole 2 and the process of pulling up the excavation compaction means 3, very little excavated earth and sand 2 a is formed in the excavation hole 2 by the compaction pieces 3 d fixed to the outer edges of the guide blades 3 c, 3 c. Although it is applied to the inner peripheral surface and is consolidated to the inner peripheral surface, most of the excavated earth and sand 2a remains in the excavated hole 2 and is consolidated to the bottom side of the excavated hole 2 in a later process. Will be.

  On the other hand, instead of the excavation compaction means 3 as described above, most of the excavated earth and sand 2a generated during excavation is consolidated to the inner peripheral surface of the excavation hole 2 so that no excretion can be achieved. There are also soil excavation means, and such means can also be used to implement the method of the present invention. However, when such a means is used, the excavated earth and sand 2a is not discharged on the upper surface of the ground g, and there is no possibility that the groundwater comes out from the inner peripheral surface of the excavation hole 2. Since the amount of the excavated earth and sand 2a remaining in the excavation hole 2 is reduced, it may be difficult to form the support layer 4 that can ensure the design support force depending on the consolidation of the excavated earth and sand 2a alone. . Therefore, in this case, in order to form the support layer 4 capable of securing the design support force by compacting up to the design depth, an appropriate amount of support layer forming material such as crushed stone 2b is added on the excavated soil 2a of the excavation hole 2. It is essential to input.

Thereafter, the second stage support layer forming step is performed. This step is started by placing the excavation compaction means 3 on the upper surface of the excavation earth and sand 2a at the upper opening of the excavation hole 2, as shown in FIG. Naturally, the excavation compaction means 3 is arranged upright in the center of the upper surface of the excavation hole 2. In this state, the rotary drive device is reversely rotated, and the steel pipe 3a of the excavating and compacting means 3 is reversely rotated as shown in FIGS. 2 (d) and 2 (e), and sufficient for the steel pipe 3a. Under load, the excavated earth and sand 2a is consolidated downward. Since the lowermost excavation blade 3b of the excavation compaction means 3 rotates in the opposite direction to that during excavation by the reverse rotation operation of the rotary drive device, the lower excavation soil 2a passes through the gap between the blades. It does not move upward, and as shown in FIG. 2 (e), it is consolidated downward by the load.
This consolidation can be performed entirely or partially without rotating the excavation consolidation means 3. In particular, in the final stage of consolidation reaching the design depth immediately before the design depth, it is appropriate to perform consolidation without rotation.

  Thus, as shown in FIG. 3, the consolidation operation is continued to the design depth. As described above, in this final consolidation stage, the excavation consolidation means 3 is stopped from rotating and a large load is applied to perform a strong consolidation operation. In addition, at the stage where the excavated sediment 2a is consolidated to the design depth, it is confirmed whether or not the support layer 4 capable of ensuring a predetermined support force is applied to the steel pipe 3a of the excavation compaction means 3 by applying an appropriate load greater than the design support force. As described above, if the steel pipe 3a does not descend even when a constant load equal to or greater than the design support force is applied to the steel pipe 3a, the consolidation process is completed. At this stage, it can be determined that the support layer 4 capable of ensuring a support force equal to or greater than the design support force is formed below the bottom surface of the excavation hole 2.

  At this stage, that is, when the load of the design support force is applied at the stage where the consolidation operation is advanced to the design depth, if the excavation compaction means 3 is further lowered, an appropriate amount of the excavation compaction means 3 is provided. The crushed stone (support layer forming material) 2b is pulled up to a height suitable for charging, and the excavation compaction means 3 is rotated in the reverse direction while rotating the excavation compaction means 3 and the steel pipe 3a of the excavation compaction means 3. In the meantime, an appropriate amount of crushed stone 2b is introduced into the bottom side of the drilling hole 2 through the gap between the guide wings 3c, 3c... And the excavating wing 3b. It will be consolidated. In the final stage of compaction immediately before the design depth, as described above, the excavation compaction means 3 is stopped and the compaction operation is performed with a large load. At the stage of consolidation to the design depth, it is checked again whether a load exceeding the design support force is applied, and if so, formation of the support layer 4 is complete, but it must be. In this case, the same cycle is repeated again.

  As described above, when the crushed stone 2b is introduced while the excavation compaction means 3 is rotated in the reverse direction (rotation in the direction opposite to the rotation during excavation), the crushed stone 2b is converted into the guide blades 3c, 3c. Therefore, it does not stay in the middle of the depth direction of the excavation hole 2 and can be charged and lowered to the lowest part. The guide blades 3c, 3c,... Have a consolidation piece 3d fixed to the outer edge of the blade, and as described above, the excavation hole 2 is formed in the excavation hole 2 in the drilling process and the excavation consolidation means 3 in the lifting process. Since the inner peripheral surface is consolidated and the inner peripheral surface is stabilized, the stagnation of the crushed stone 2b that has been thrown in is also prevented.

  Thus, as described above, even if a load greater than the design support force is applied to the excavation compaction means 3, if the excavation compaction means 3 does not descend from this, the support layer forming process is completed. As shown in FIG. 3, the excavation hole 2 in which the support layer 4 capable of ensuring the design support force at the design depth is completed.

Thereafter, as described above, the third step of forming the crushed stone pile is performed.
In this step, as shown in FIG. 4 (a), the excavating and compacting means 3 is pulled up to an appropriate height, and while rotating it reversely, an appropriate amount of crushed stone 2b is excavated from the inner peripheral surface of the excavating hole 2. The guide blades 3c, 3c... And the excavating blade 3b are inserted into the bottom of the excavation hole 2 through the gap between the steel pipe 3a and the excavating vane 3b. As described above, the crushed stone 2b can be smoothly introduced into the bottom of the excavation hole 2 by the action of the guide blades 3c, 3c.

  Thereafter, as shown in FIG. 4 (b), the excavation compaction means 3 is lowered, and the lowermost excavation blade 3b is placed on the crushed stone 2b. Similarly, the crushed stone 2b is reversely rotated (in the reverse direction of excavation rotation). The crushed stone 2b is compacted by pressurizing with a predetermined load while rotating. This compaction can also be performed without rotation of the excavation compaction means 3. When the consolidation operation is performed in this way and the excavation compaction means 3 is not lowered even when a predetermined load is applied, the excavation compaction means 3 is pulled up, as shown in FIG. 5 (c), and as described above. While rotating the excavation compaction means 3 in the reverse direction, the bottom portion of the excavation hole 2 through the gap between the inner peripheral surface of the excavation hole 2 and the steel pipe 3a of the excavation compaction means 3 and the blades of the guide vanes 3c, 3c. An appropriate amount of crushed stone 2b is introduced to the side, and as shown in FIG. 5 (d), the excavation compaction means 3 is lowered, and the excavation blade 3b is placed on the crushed stone 2b. While pressing the crushed stone 2b and rotating it in the same manner, the crushed stone 2b is compacted.

This cycle of charging the predetermined amount of crushed stone 2b and compaction by the excavation compaction means 3 is repeated, and as shown in FIG. 6 (e), the crushed stone 2b is introduced to the uppermost opening of the excavation hole 2, and the excavation consolidation is performed. After compaction by means 3, as shown in FIG. 6 (f), the crushed stone 2b is filled to fill the upper surface of the slightly lowered crushed stone 2b and raised slightly, and a press-fitting plate 5 is placed thereon. On the top, the excavation compaction means 3 performs compaction from above the press-fitting plate 5 without rotation. As shown in FIG. 7, if the upper surface of the crushed stone 2b is consolidated until it reaches the same level as the upper surface of the ground g, the formation of the crushed stone pile 1 is completed, and the execution method of the crushed stone pile is completed as a whole.
The press-fitting plate 5 is a metallic plate material having a predetermined strength.

  Thus, the support layer 4 was formed at the design depth, and the crushed stone pile 1 having a sufficient support force supported by the support layer 4 could be formed.

<Example 2>
The pile construction method of Example 2 is applied to the construction of a steel pipe pile. The first stage is a drilling hole drilling process for drilling the drilling hole 12 in the target ground, and the second stage is drilling. The support layer forming step of forming the support layer 14 at the design depth by consolidating the excavated earth and sand in the excavated hole 12, and the third step is a step of pressing the steel pipe pile into which the steel pipe pile 15 is press-fitted into the excavated hole 12. As a whole, the steel pipe pile construction method is carried out.

  The drilling process of the first stage excavation hole in Example 2 and the support layer formation process in the second stage are different in detail from the construction method of the crushed stone pile in Example 1, but are basically the same. Explanation is omitted, and only the press-fitting process of the third stage steel pipe pile will be explained. The difference in details from Example 1 in the drilling hole drilling process in the first stage and the support layer forming process in the second stage is the diameter of the drilling hole 12, the design depth, and the design support force of the support layer, This naturally corresponds to the corresponding steel pipe pile 15.

  In the second embodiment, as shown in FIGS. 8A and 8B, the steel pipe pile 15 is a cylindrical one having a diameter slightly larger than the diameter of the excavation hole 12. The lower end is configured as a tapered point. The steel pipe pile 15 is made to stand upright in the upper opening of the excavation hole 12 with the mutual axial centers substantially coincided with each other. This can be done using a construction machine, such as a hydraulic excavator, suspended by a hook coupled to the vicinity of the arm tip with the bucket removed.

  Next, a protective cap (not shown) is put on the upper end of the steel pipe pile 15. The protective cap is a metal cylindrical body having an inner diameter that can be smoothly fitted to the upper portion of the steel pipe pile 15, and a non-rotating pressure device such as an impact pressure device or a vibration pressure device is used on the upper portion of the steel pipe pile 15. This is intended to prevent damage to the upper portion of the steel pipe pile 15 during pressurization.

  In the second embodiment, the steel pipe pile 15 is press-fitted into the excavation hole 12 by the pressurization of the breaker, and the hitting pressurization is applied to the upper end of the steel pipe pile 15 via the protective cap. I will do it. Further, as shown in FIG. 8 (b), the impact pressing is performed until the lower end of the steel pipe pile 15 is press-fitted into the support layer 14 formed at the design depth. Needless to say, the steel pipe pile 15 is easily lowered with a small impact pressure until the lower end of the steel pile pile 15 reaches the support layer 14. From the time when the lower end reaches the support layer 14, it is driven with a large striking force. The steel pipe pile 15 is driven at its lower end by a dimension corresponding to its diameter until it is in a press-fitted and embedded (rooted) state in the support layer 14.

  When the steel pipe pile 15 is driven in such a manner that the lower end of the steel pipe pile 15 is pressed into the support layer 14 by an amount corresponding to the diameter thereof, the execution of the steel pipe pile construction method of Example 2 is completed.

  In Example 2, a simple cylindrical steel pipe having a pointed end at the lower end was used as the steel pipe pile 15, but a plurality of ribs were arranged along the length direction on the outer periphery to increase the frictional force. It is also possible to adopt. In addition, various types of steel pipes can be employed, and are not limited to specific ones.

The steel pipe pile 15 of this Example 2 is designed for soft ground, for example, even when it has an N value (standard penetration test value) of about 1 and does not have a sufficient support layer at a predetermined depth. Since the support layer 14 capable of securing a force, for example, about 30 kN / m ² , can be formed and the lower end can be supported by the support layer 14, the target support force can be easily obtained.

  The method for constructing piles of the present invention can be effectively used in the field of civil engineering or construction for constructing piles such as crushed stone piles, steel pipe piles, concrete piles or cement-based on-site created piles.

DESCRIPTION OF SYMBOLS 1 Crushed stone pile 2 Drilling hole 2a Drilling earth and sand 2b Crushed stone 3 Drilling compaction means 3a Steel pipe 3b Drilling blade 3bb Drilling blade 3c Guide blade 3d Consolidation piece 4 Support layer 5 Press-fit plate 12 Drilling hole 14 Support layer 15 Steel pipe pile g Ground

Claims (5)

Excavating the ground in the vertical direction, consolidating the excavated soil in the resulting excavation hole, forming a support layer that can secure a support force higher than the design support force in the ground at the design depth,
A method for constructing piles in which piles having a lower portion supported by the support layer are disposed.   A support layer forming material containing gravel or crushed stone is added to the excavated soil before or during consolidation, and the support layer forming material is compacted from the top of the support layer forming material to the design depth, and the design bearing capacity is in the ground at the design depth. The pile construction method according to claim 1, wherein a support layer capable of securing the above support force is formed.   The construction method of the piles of Claim 1 or 2 which employ | adopted the crushed stone pile, the steel pipe pile, the concrete pile, or the cement system field creation pile as said piles. An installation process of the excavation consolidation means for standing up the excavation consolidation means made of a steel pipe with a spiral excavation blade attached to the lower end at a required position of the ground; and
A ground excavation step of excavating the steel pipe of the excavation compaction means to a required depth by driving forward rotation while applying a load for excavation by the rotation drive means;
A step of lifting the excavation compaction means for pulling up the excavation compaction means while driving the excavation blade in reverse rotation;
A predetermined descending load is applied while rotating the steel pipe of the excavation compaction means in a reverse rotation or without rotation, and the excavated sediment in the excavation hole or the excavated sediment and the crushed stone thrown thereon are the excavated blades at the bottom of the steel pipe And a support layer forming step of forming a support layer that can be consolidated to the design depth at the lower end of the steel pipe to ensure a support force equal to or greater than the design support force;
The excavation compaction means is pulled up by a height corresponding to the amount of crushed stone input, and the amount of crushed stone is charged into the gap between the peripheral side of the steel pipe and the inner periphery of the drilling hole. While reversely rotating the compaction means, the crushed stone is further introduced to the lower side of the excavation hole through the gap between the spiral excavation blades, and then the crushed stone is reversely rotated by the excavation blade of the excavation compaction means or In a non-rotating state, a crushed stone pile forming step of repeating a compaction cycle to be consolidated at the lower end of the excavation blade and the lower end of the steel pipe until reaching the upper end opening of the excavation hole,
A method for constructing crushed stone piles in order. A steel pipe installation process for standing up a drilling and compacting means composed of a steel pipe with a spiral excavation blade attached to the lower end at a required position of the ground; and
A ground excavation step of excavating the steel pipe of the excavation compaction means to a required depth by driving forward rotation while applying a load for excavation by the rotation drive means;
A step of lifting the excavation compaction means for pulling up the excavation compaction means while driving the excavation blade in reverse rotation;
A predetermined descending load is applied while rotating the steel pipe of the excavation compaction means in a reverse rotation or without rotation, and the excavated sediment in the excavation hole or the excavated sediment and the crushed stone thrown thereon are the excavated blades at the bottom of the steel pipe And a support layer forming step of forming a support layer that can be consolidated to the design depth at the lower end of the steel pipe to ensure a support force equal to or greater than the design support force;
A re-pumping step of the excavation compaction means for pulling up the excavation compaction means;
A steel pipe pile is inserted into the excavation hole, and a lower end of the steel pipe pile is press-embedded (incorporated) into the support layer;
A steel pipe pile construction method that performs in that order.

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