JP6147507B2 - Construction method and steel pipe for construction of in-situ tapered concrete piles with knots - Google Patents

Description

The present invention method for constructing a concrete-based pile sections with cast-in-place tapered Concrete piles having a spiral section, particularly an outer peripheral surface constructed by cast-in-place in the ground to support the foundation of buildings, and the construction The present invention relates to a steel pipe for construction of a cast-in-place concrete pile with a knot used in the method.

  When building a building on soft ground, the ground is reinforced by a columnar improvement method, a method of burying small-diameter steel pipe piles, and the like. The columnar improvement method is a method of constructing a columnar improvement pile in which soil is solidified with a solidifying material by mixing and stirring the solidified material in the excavated soil while excavating a pile hole in the ground.

  Moreover, as an alternative to the above columnar improvement method, in Patent Document 1, a pile hole is excavated in the ground with an excavation auger having an excavation claw at the tip, and a hydraulic solidifying material liquid made of cement or the like is filled in the pile hole, Thereafter, a method of constructing a replacement column in which the hydraulic solidifying material liquid is solidified by lifting the excavating auger from the ground has been proposed.

JP 2011-106253 A JP 2010-059603 A

The conventional columnar improvement method has the following problems.
・ Since soil and solidified material are mixed and stirred at the site, the quality of the built-up pillar-shaped piles varies depending on the soil quality at the site and the difference in the installer.
-In order to avoid insufficient strength due to poor solidification or poor stirring, it may be necessary to inject a large amount of solidified material slurry, which places a heavy burden on the environment.
-Depending on the soil, harmful substances such as hexavalent chromium may be eluted. Although it is possible to test whether hexavalent chromium or the like is eluted in advance and confirm that there is no dissolution, this requires cost and time.

The method of burying small diameter steel pipe piles has the following problems.
-Since it is necessary to support the tip of a small-diameter steel pipe pile on a relatively hard ground (generally N value ≧ 10), it may not be applicable depending on the ground.
・ Deterioration due to corrosion of small diameter steel pipe piles. For this reason, it is designed in advance to allow for corrosion.

  The method of Patent Document 1 does not cause the problems of the conventional columnar improvement method because the soil at the site is not mixed with the solidifying material. However, in the method of Patent Document 1, since the outer peripheral surface of the replacement column formed by solidifying the hydraulic solidifying material liquid is cylindrical without a node, the shear resistance between the outer peripheral surface of the replacement column and the surrounding ground is low. The replacement column diameter must be increased accordingly.

  Therefore, the present inventors have proposed a method for constructing a cast-in-place concrete pile as shown in FIG. 6 as a means for solving these problems (Japanese Patent Application No. 2012-188723). This construction method includes a process of preparing a drilling blade mounting steel pipe 30 (see FIG. 6A) in which a tip drilling blade 32 is detachably attached to the lower end of the steel pipe 31, and the drilling blade mounting steel pipe 30 is attached to the steel pipe 31. A process of excavating downward by the tip excavating blade 32 and inserting it into the ground 35 while forming a spiral groove 36 in the soil on the outer periphery of the steel pipe 31 by pushing down while rotating around the central axis in a certain direction (FIG. 6 ( (A), (B)), the process of filling mortar or ready concrete in the steel pipe 31 (FIG. 6C), and the pile hole 37 that becomes the trace of the steel pipe 30 by extracting only the steel pipe 31 from the ground 35. And a process of pouring mortar or ready-mixed concrete in the steel pipe 31 into the spiral groove 36 (FIGS. 6D and 6E).

  According to this construction method, only the steel pipe 31 can be pulled out from the ground 35 without breaking the spiral groove 36. Mortar or ready-mixed concrete is poured into the thus formed pile hole 37 and the spiral groove 36, and the mortar or ready-mixed concrete is hardened, so that a spiral knotted concrete pile is built in place. As a result, unlike conventional columnar improvement methods, there is no need to mix and agitate the soil and solidified material at the site, and there is no need to be affected by the soil condition at the site. Can be built. In addition, there is no concern that harmful substances such as hexavalent chromium will be eluted by the soil.

  Further, the soil around the pile hole 37 is pushed around by the steel pipe 31 and the ground 35 is compacted. Furthermore, since the constructed concrete pile has a spiral node on the outer peripheral surface, the shear resistance of the peripheral surface of the pile is large. From these things, the pile peripheral surface resistance of a concrete pile can be taken large, and a pile diameter can be made small by that much.

  However, in the case of the above proposed example, the steel pipe 31 of the excavating blade mounting steel pipe 30 has a columnar shape with the same diameter in the vertical direction, and the lower part of the pile that does not apply a large force has the same diameter as the upper part. In addition to increasing the number, it is necessary to devise the shape of the tip portion in order to facilitate the insertion of the excavating blade mounting steel pipe 30 into the ground 35. Moreover, the problem that it is not easy to form the spiral groove 36 when the excavating blade mounting steel pipe 30 is inserted into the ground 35 is not easy because the hole wall of the pile hole 37 tends to collapse.

Inventions of the purpose of this is, a stable Concrete piles for the ground reinforcement of quality without being influenced by the state of the field of soil can be constructed in a simple, and pile the peripheral surface of the constructed concrete-based pile It is to provide a method for constructing a cast-in-place concrete pile with knots with high resistance.
Another object of the present invention is to provide a steel pipe for constructing a spot-cast concrete pile that can be used in the above-described method for constructing a spot-cast concrete pile with a knot and improve its workability.

The in-situ taper-shaped concrete pile with a node constructed by the method of the present invention is a pile constructed in the field by mortar, concrete, or cement milk, and a conical trapezoidal pile body whose lower side is narrowed, and a lower part of the pile body And the outer diameter of the spiral node is smaller than the outer diameter of the upper end of the pile body.

  According to this jointed-in-place tapered concrete pile with a knot, the pile body has a conical trapezoidal shape whose bottom is narrowed, and the lower part where a large force is not applied has a small diameter, so that the amount of material can be reduced. Moreover, since it has the spiral node which digged into the ground in the outer periphery of the lower part of a pile main body, the shear resistance of a pile surrounding surface increases and a pile surrounding surface resistance force becomes large. Thereby, the amount of material is small and it can be set as the in-situ cast-in-place concrete pile with a large pile peripheral surface resistance force.

  The method for constructing a field cast-in-place concrete pile with a knot according to the present invention is a construction of a pile in which concrete, mortar or cement milk is poured into the pile construction steel pipe when the pile construction steel pipe is rotated and entered. The pile construction steel pipe has a conical trapezoidal steel pipe whose lower side is narrowed, and a drilling blade provided at the lower end of the steel pipe, and the distance from the steel pipe center to the tip of the drilling blade is By using a steel pipe for construction of a pile shorter than the radius of the upper end of the steel pipe, it has a truncated cone-shaped pile body narrowed on the lower side and a spiral node protruding on the outer periphery of the lower part of the pile body. A pile is constructed in which the outer diameter of the node is smaller than the outer diameter of the upper end of the pile body.

  According to this method for constructing a cast-in-place concrete pile with a knot, the steel pipe of the pile construction steel pipe to be used is a truncated cone shape whose bottom is narrowed, so that the steel pipe can be easily inserted into the ground. Moreover, the hole wall of a pile hole is hard to collapse, and the groove | channel for forming a spiral node in the lower peripheral surface of a pile hole can be formed easily. As a result, it is possible to easily construct a concrete pile for ground reinforcement with stable quality without being affected by the soil condition at the site, and to increase the pile peripheral surface resistance force of the constructed concrete pile. .

  The steel pipe for constructing a cast-in-place concrete pile with a node according to the present invention has a conical trapezoidal steel pipe whose bottom is narrowed, and a drilling blade provided at the lower end of the steel pipe. The distance is shorter than the radius of the upper end of the steel pipe.

  According to this steel pipe for construction of cast-in-place concrete piles with knots, a drilling blade is provided at the lower end of the conical trapezoidal steel pipe that narrows the lower side, so it is easy to penetrate into the ground and spreads the soil, so it can be easily removed without waste It can be constructed and used in the above pile construction method to improve its workability.

  In the steel pipe for construction of a piling-type concrete pile with a knot, the conical trapezoidal steel pipe has an outer diameter at the lower end that is approximately ½ of the outer diameter at the upper end, and has a height protruding from the outer peripheral surface of the steel pipe of the excavating blade. It is good also as 20 mm or more.

  The method for constructing a field cast-in-place concrete pile with a knot according to the present invention is a construction of a pile in which concrete, mortar or cement milk is poured into the pile construction steel pipe when the pile construction steel pipe is rotated and entered. The pile construction steel pipe has a conical trapezoidal steel pipe whose lower side is narrowed, and a drilling blade provided at the lower end of the steel pipe, and the distance from the steel pipe center to the tip of the drilling blade is By using a steel pipe for construction of a pile shorter than the radius of the upper end of the steel pipe, it has a truncated cone-shaped pile body narrowed on the lower side and a spiral node protruding on the outer periphery of the lower part of the pile body. Since the construction of the pile with the outer diameter of the knot smaller than the outer diameter of the upper end of the pile body, it is easy to make a concrete pile for ground reinforcement with stable quality without being affected by the soil condition at the site. It can be constructed, and it is possible to increase the pile circumferential surface resistance of the constructed Concrete piles.

  The steel pipe for constructing a cast-in-place concrete pile with a node according to the present invention has a conical trapezoidal steel pipe whose bottom is narrowed, and a drilling blade provided at the lower end of the steel pipe. Since the distance is shorter than the radius of the upper end of the steel pipe, it can be used in the above-described method for constructing the in-situ cast-in-place concrete pile and its workability can be improved.

It is sectional drawing of the ground by which the pile was constructed | assembled with the construction method of the field cast taper-concrete pile with a node concerning one Embodiment of this invention. It is a side view which shows the whole structure of an example of the construction apparatus which constructs the node cast-in-place taper concrete pile shown in FIG. (A) is a perspective view of an example of the steel pipe for construction of a cast-in-place concrete pile with a node, and (B) is a perspective view of another example of the steel pipe. (A) is a model front view which shows the lower end of an example of the steel pipe for construction of a cast-in-place concrete pile with a node, (B) is a model front view which shows the lower end of the other example of the steel pipe. It is explanatory drawing which shows each process of the construction method of the in-situ cast-in-place concrete pile performed using the steel pipe shown to FIG. 3 (A). It is explanatory drawing of the example of a proposal of the construction method of a cast-in-place concrete pile with a node.

The construction method of the field cast-in-place concrete pile of this invention is demonstrated with FIG. 1 thru | or FIG.
This method for constructing a knotted concrete cast-in-place pile is a method for constructing a knotted concrete cast-in-field pile 20 with a knot shown in FIG. 1 by using a construction apparatus including a steel pipe for pile construction. The built-in-site tapered concrete pile 20 with a knot has a conical trapezoidal pile main body 21 whose lower side is narrowed, and a spiral knot 22 that protrudes from the outer periphery of only the lower portion of the pile main body 21. The outer diameter of the spiral node 22 is set to be smaller than the outer diameter of the upper end of the pile body 21 even at the maximum diameter portion.

  FIG. 2 is a side view showing an overall configuration of an example of a construction apparatus for constructing the above-mentioned knotted tapered concrete pile 20 with a node. The illustrated construction apparatus 1 includes a pile driving device 1a, a mortar supply device 1b, and a steel pipe 10 for pile construction.

  In the pile driving device 1a, a guide column 3 is supported by a work vehicle 2 capable of self-propelling so that the inclination of the pile driving device 2 can be changed, and an upper end of a steel pipe 10 for pile construction is held by an elevating head 4 that can be moved up and down along the guide column 3. The The pile construction steel pipe 10 can be rotated by a rotary motor 5 provided in the elevating head 4. Further, the elevating head 4 is provided with a vibrator 6 that gives vibration to the pile construction steel pipe 10.

  The mortar supply device 1b includes a tank 7 containing mortar and a hose 8 for sending out the mortar in the tank 7. The tank 7 is a separate vehicle from the work vehicle 2.

  As shown in FIG. 3A, the pile construction steel pipe 10 includes a conical trapezoidal steel pipe 11 whose lower side is narrowed, and a drilling blade 12 attached to the lower end portion of the steel pipe 11. The distance r1 from the steel pipe center to the tip of the excavating blade 12 is set to be shorter than the radius r2 of the upper end of the steel pipe 11. Specifically, as shown in FIG. 4A, the conical trapezoidal steel pipe 11 has an outer diameter A at the lower end substantially equal to 1/2 (190.mm) of the outer diameter at the upper end (for example, 190.7 mmφ or 216.3 mmφ). 7/2 mmφ = 95.35 mmφ or 216.3 / 2 mmφ = 108.15 mmφ), and the length B protruding from the steel pipe 11 of the digging blade 12 is 20 mm or more to the outer edge of the upper end of the steel pipe 11 (˜47.7 mm or 54.1 mm) is preferable.

  In addition, as another example of the steel pipe 10 for pile construction, as shown in FIG. 3 (B), the shape of the steel pipe 11 is a cylindrical shape with a uniform upper diameter in the upper and lower sides, and only the lower half is on the lower side. It may be a conical trapezoid that narrows. Moreover, in the example of the pile construction steel pipe 10 shown in FIG. 3, FIG. 4 (A), and FIG. 5, two blade bodies in which the excavation blades 12 are arranged back to back on the outer peripheral surface of the lower end of the steel pipe 11. Although the case where it consists of 12a was shown, you may use the spiral blade body (auger) as shown in FIG. Also in this case, it is preferable to set the outer diameter A of the lower end of the conical trapezoidal steel pipe 11 and the height B protruding from the steel pipe 11 of the excavating blade 12 in the same manner as in the example of FIG.

The construction method of the in-situ concrete pile with a node performed using the steel pipe 10 for pile construction shown to the said FIG. 3 (A) is demonstrated.
First, as shown in FIG. 2, the pile construction steel pipe 10 is prepared by holding the upper end of the steel pipe 11 with the lifting head 4 of the construction apparatus 1. The position of the pile construction steel pipe 10 is adjusted by the work vehicle 2 so that the piled steel pipe 10 is positioned directly above the site-installed tapered concrete-type pile construction site with a node.

  In this state, the rotary motor 5 is driven to rotate the pile construction steel pipe 10 around the central axis of the steel pipe 11 in a predetermined rotation direction (for example, clockwise), while moving the lifting head 4 along the guide pillar 3 at a constant speed. The pile construction steel pipe 10 is pushed down and pushed down. Thus, the pile construction steel pipe 10 is inserted into the ground 15 while excavating downward with the excavation blade 12 at the lower end of the steel pipe 11 and forming the spiral groove 16 in the outer periphery of the steel pipe 11. At this time, when the excavating blade 12 rotates, a downward driving force acts on the entire pile construction steel pipe 10, thereby forming a regular-shaped spiral groove 16 having a constant interval.

  When the above operation is continued and the pile building steel pipe 10 is inserted into the ground 15 to a predetermined depth from the ground surface as shown in FIG. 5A, the driving of the rotary motor 5 and the lowering of the lifting head 4 are stopped. . At this time, since the steel pipe 11 is a conical trapezoid whose bottom is narrowed, the spiral groove formed in the soil on the outer periphery of the steel pipe 11 during the insertion is crushed by the outward pressing force of the steel pipe 11.

  Next, the hose 8 of the mortar supply device 1 b is inserted into the steel pipe 11 of the pile construction steel pipe 10 from the upper end side, and the tip of the hose 8 is extended to the vicinity of the lower end of the steel pipe 11. And the mortar M is discharged from the front-end | tip of the hose 8 (FIG. 2), and the mortar M (refer FIG. 5 (B)) is filled to the upper end in the steel pipe 11. FIG.

  When the filling of the mortar M is completed, the hose 8 of the mortar supply device 1b is extracted from the steel pipe 11, and then the elevating head 4 is raised at a constant speed while driving the rotary motor 5 in the reverse rotation direction. As shown in FIG. 5B, by lifting the pile construction steel pipe 10 while rotating it in the reverse rotation direction (for example, counterclockwise) from the time of lowering, the spiral groove 16 is formed only on the outer periphery of the lower part. Further, by pulling up the pile construction steel pipe 10, only the pile construction steel pipe 10 is pulled out from the ground 15 as shown in FIG. The mortar M in the steel pipe 11 flows into the groove 16. When pulling up the pile construction steel pipe 10, the vibrator 6 (FIG. 2) vibrates the steel pipe 11, so that the mortar M is compacted, and the mortar M is completely removed to the corners of the pile hole 17 and the spiral groove 16. Can be spread.

  After the pile construction steel pipe 10 is completely pulled out as shown in FIG. 5C, the top portion Ma of the mortar M poured into the pile hole 17 and the spiral groove 16 is then smoothed smoothly. This completes the construction. When the mortar M is hardened, it becomes a knotted in-situ tapered concrete pile 20 shown in FIG.

  This jointed-in-place tapered concrete pile 20 with a node has a spiral node 22 on the outer periphery of the lower part of a conical trapezoidal pile body 21 narrowed on the lower side, and this spiral node 22 bites into the ground 15. Further, in the process of inserting the pile construction steel pipe 10 into the ground 15, the soil in the upper half of the portion that becomes the pile hole 17 is pushed around by the steel pipe 11 and the ground 15 is compacted. Therefore, the shear resistance of the pile peripheral surface increases and the pile peripheral surface resistance force can be increased. Moreover, when the pile peripheral surface resistance force is large, the outer diameter of the pile main body 21 can be reduced accordingly, and the outer diameter of the lower portion of the pile main body 21 is further reduced by the effect of biting into the ground 15 of the spiral node 22. can do. As a result, it is possible to reduce the amount of material required for the construction of the in-situ tapered concrete pile 20 with a knot, and the cost can be reduced. Since the lower part of the pile main body 21 is not subjected to a large force, the required strength is ensured even with a small diameter. In addition, since the amount of material can be reduced, the environmental load can be reduced. Moreover, when a pile peripheral surface resistance force is large, it can support also in the place where N value of a pile front-end ground is comparatively small, and a pile length can be shortened.

  This method of constructing on-site cast-in-place concrete piles does not involve mixing and stirring the soil and solidified material, unlike the conventional columnar improvement method, so it is not affected by the soil condition at the site. It is possible to construct an in-situ tapered concrete pile 20 with a knot for stable ground reinforcement. In addition, there is no worry of toxic substances such as hexavalent chromium eluting depending on the soil.

  In the construction method described above, mortar M is used as the material of the in-situ tapered concrete pile 20 with a node, but instead of mortar M, ready-mixed concrete or cement milk (mixture of cement and water) may be used. .

  Moreover, since the steel pipe 11 for pile construction used for the said construction method is a conical trapezoid in which the lower side was narrowed, in order to easily penetrate into the ground and to spread the soil, it is simply constructed without waste soil. be able to.

  The cost required for an example of a nodal on-site tapered concrete pile 20 constructed by the construction method of the above embodiment is the same as that of the nodal on-site concrete pile 40 constructed by the proposed construction method shown in FIG. The results compared with the cost required for an example are shown in Table 1 below.

  In the table, the column at the left end shows each data of the cast-in-place concrete pile 40 (cylinder diameter 190.70 mmφ) with a node constructed by the construction method of the proposed example shown in FIG. The column of the table shows each data of the node cast-in-place tapered concrete pile 20 (upper diameter 190.70 mmφ) constructed by the construction method of the above embodiment. Also, the column on the right next to the column shows data of another on-site cast-in-place concrete pile 40 (cylinder diameter of 216.30 mmφ) constructed by the construction method of the proposed example shown in FIG. The column of the truncated cone shows each data of another node-placed in-situ tapered concrete pile 20 (upper diameter 216.30 mmφ) constructed by the construction method of the above embodiment. As a result, the volume ratio is reduced by about 40%. The dimensions of the joints of the pile have not been examined.

  From this comparison result, it is understood that the material cost can be greatly reduced in the field cast tapered concrete pile 20 with a node according to this embodiment as compared with the case of the proposed example.

DESCRIPTION OF SYMBOLS 10 ... Steel pipe 11 for pile construction | steel 11 ... Steel pipe 12 ... Excavation blade 15 ... Ground 16 ... Spiral groove 17 ... Pile hole 20 ... In-situ tapered concrete pile 21 with a knot ... Pile main body 22 ... Node M ... Mortar

Claims (3)

A pile construction method in which a steel pipe for pile construction is entered while rotating into the ground, and concrete, mortar, or cement milk is poured into the interior when the steel pipe for pile construction is pulled out,
As the steel pipe for pile construction,
A steel pipe for pile construction having a conical trapezoidal steel pipe whose bottom is narrowed, and a drilling blade provided at the lower end of the steel pipe, the distance from the steel pipe center to the tip of the drilling blade being shorter than the radius of the upper end of the steel pipe By using
A pile having a conical trapezoidal pile body whose bottom is narrowed and a spiral node projecting to the outer periphery of the lower portion of the pile body, and the outer diameter of the spiral node is smaller than the outer diameter of the upper end of the pile body It is characterized by building
Construction method of on-site concrete piles with knots.   It has a conical trapezoidal steel pipe whose bottom is narrowed, and a drilling blade provided at the lower end of the steel pipe, and the distance from the steel pipe center to the tip of the drilling blade is shorter than the radius of the upper end of the steel pipe Steel pipe for construction of on-site concrete piles with knots. The steel pipe for construction of a cast-in-place concrete pile with a knot according to claim 2 , wherein the conical trapezoidal steel pipe has an outer diameter of a lower end substantially equal to an outer diameter of the upper end, and an outer peripheral surface of the steel pipe of the excavating blade. Steel pipe for construction of on-site cast-in-place concrete piles with a length of 20mm or more protruding from the ground.

Images