JP5992464B2 - Excavation blade mounting steel pipe for construction of cast-in-place concrete pile and construction method of cast-in-place concrete pile - Google Patents

Description

  The present invention relates to an excavating blade-attached steel pipe for building a cast-in-place concrete pile used for building a concrete-based pile built in-situ in the ground to support the foundation of the building, and a method for building a cast-in-place concrete pile .

  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.

  As an alternative to the above-mentioned columnar improvement method, Patent Document 1 discloses excavation while excavating a pile hole in the ground with an excavation auger having an excavation claw at the tip, and filling the pile hole with a hydraulic solidified liquid made of cement or the like. A method of constructing a replacement column in which a hydraulic solidifying liquid is solidified by pulling out an auger from the ground has been proposed.

  Further, in Patent Document 2, a tip head having a drilling blade is detachably attached to a lower end of a cylindrical casing made of a steel pipe or the like, and the casing and the tip head are rotated and penetrated into the ground. A method of constructing a concrete pile has been proposed by filling cement milk or the like, and then separating the tip head from the casing and pulling out only the casing from the ground.

JP 2011-106253 A JP 2006-77388 A JP 2010-59603 A JP 2004-124398 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 front-end | tip of a small diameter steel pipe pile on comparatively hard ground (generally N value> 10), it may not be applied 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.

  Since the construction method of Patent Document 1 does not mix the soil at the site with the solidification material, each problem of the conventional columnar improvement construction method does not occur. However, in the method of Patent Document 1, a part of the inner peripheral surface of the pile hole collapses when the excavation auger is pulled out from the ground, and soil is mixed into the hydraulic solidification material liquid, so that a good replacement column may not be formed. There is sex.

  In the construction method of Patent Document 2, since the casing is pulled out from the ground after filling the cylindrical casing with cement milk or the like, there is no fear that the inner peripheral surface of the pile hole collapses. In this construction method, the tip head is detachably attached to the casing. When the casing is pulled out from the ground, the tip head is separated from the casing, and the tip head is left at the bottom of the pile hole. For this reason, it is required that the tip head is easily attached to the casing and that the tip head is reliably separated from the casing.

  In Patent Document 2, a specific example of the structure for attaching and detaching the tip head to the casing is shown in paragraphs 0032 to 0036 and FIGS. 1 to 3 of the document. That is, the front end head is attached to and detached from the casing by inserting and withdrawing the convex portion provided on the main body peripheral wall portion of the front end head in the notch formed on the inner peripheral surface of the lower end of the casing. When the casing is rotated in a predetermined direction with the convex portion inserted into the notch, the convex portion is locked to the notch, and the leading end head is swung around the casing. Even if the rotation of the casing is stopped, since the convex portion is received from below by the hook portion of the notch portion, the tip head is not separated from the casing. When the casing is rotated in the reverse direction, the convex portion is detached from the hook portion of the cutout portion, so that the tip head can be separated from the casing.

  In the mounting structure of the above example, when the tip head is mounted on the casing, the tip head is mounted on the casing in a state where the axial centers of the casing and the tip head are aligned and the circumferential phase of the notch and the convex is aligned. Since the relative movement in the axial direction is required, it is troublesome to mount the tip head. In addition, in order to prevent dirt from entering the casing, in the state where the tip head is mounted on the casing, the entire outer periphery of the main body peripheral wall portion of the tip head is fitted to the inner periphery of the casing. Even if it is rotated, the tip head rotates around the casing due to frictional resistance between the inner peripheral surface of the casing and the outer peripheral surface of the main body peripheral wall of the tip head, and the convex portion does not come off from the hook portion of the notch, Even if it comes off, the main body peripheral wall portion of the tip head may not come off from the inner peripheral surface of the casing, and the tip head may not be separated. If the tip head is not separated, the cement milk or the like filled in the casing will be lifted together with the casing.

The purpose of this invention is to build a concrete pile for ground reinforcement with stable quality without being affected by the soil condition at the site, and to construct a concrete pile easily and reliably on site. It is to provide an excavating blade-attached steel pipe for on-site concrete pile construction that can be done.
Another object of the present invention is to enable the construction of a concrete pile for ground reinforcement with stable quality without being affected by the soil condition at the site. It is to provide a construction method of on-site concrete piles that can be built.
Still another object of the present invention is to make it possible to build a cast-in-place concrete pile that is difficult to collapse when the spiral groove is formed in the ground and the node is provided.

An excavating blade mounting steel pipe for building a cast-in-place concrete pile according to the present invention includes a steel pipe and a tip excavating blade which is detachably attached to the tip of the steel pipe and has an excavating blade on the tip surface. protrusions protruding to the inner diameter side to the inner peripheral surface of the distal end is provided Rutotomoni, wherein the tip digging edge, said tip digging edge abuts on the projection when the steel pipe is rotated in the drilling rotation direction determined around the axis A rotation receiving portion for rotating the steel pipe integrally with the steel pipe, and when the steel pipe is pulled up while rotating in a direction opposite to the excavation rotation direction, the tip excavation blade is axially moved with respect to the steel pipe. A separation restricting section that restricts separation is provided .

Construction of a cast-in-place concrete pile using an excavating blade-attached steel pipe for construction of a cast-in-place concrete pile of this configuration is performed as follows.
First, a drilling blade mounting steel pipe is prepared by attaching a tip drilling blade to the tip of the steel pipe. The tip excavating blade is attached to the steel pipe by allowing the rotation receiving portion and the separation restricting portion of the tip excavating blade to enter the steel pipe with the axis of the steel pipe and the tip excavating blade aligned. It is not necessary to match the circumferential position of the steel pipe and the tip excavation blade. For this reason, in order to move the tip head relative to the casing in the axial direction with the axial centers of the casing and the tip head aligned, and with the circumferential phase of the notch and the convex aligned. In comparison, it is easy to install. Note that after the rotation receiving portion and the separation restricting portion enter the steel pipe, the tip excavating blade is rotated in either one of the circumferential directions so that the separation restricting portion is locked to the protrusion of the steel pipe. When the excavating blade mounting steel pipe is supported so that the tip excavating blade is on the lower side, the tip excavating blade can be prevented from dropping from the steel pipe by its own weight.

  The excavator blade-attached steel pipe thus prepared is excavated downward by the tip excavator blade by pushing down while rotating in the predetermined excavation rotation direction with the tip excavator blade being supported downward. While penetrating into the ground. At this time, the rotation receiving portion of the tip excavation blade comes into contact with the protrusion of the steel pipe, so that the rotation of the steel pipe is transmitted to the tip excavation blade. The excavation rotation direction is a direction in which the protrusion of the steel pipe and the regulation separating portion of the tip excavation blade are not locked to each other by rotation. For this reason, the regulation separating portion of the tip excavating blade is not locked to the protrusion of the steel pipe, but the tip excavating blade is pressed against the ground, so that the tip excavating blade is not separated from the steel pipe in the axial direction.

  Next, mortar, ready-mixed concrete, or cement milk is filled into the steel pipe of the excavating blade mounting steel pipe that has penetrated into the ground. After that, the steel pipe is pulled up while rotating in the same direction as when penetrating. Since the restriction separating portion of the tip excavation blade is not locked to the protrusion of the steel pipe, the tip excavation blade is separated from the steel pipe and left as it is, and only the steel pipe is pulled out. Since the protrusion and the separation restricting portion are constantly kept from being locked to each other from the penetration of the steel pipe to the drawing, the tip excavation blade is reliably separated from the steel pipe. By pulling out only the steel pipe from the ground, the mortar, ready-mixed concrete, or cement milk in the steel pipe flows into the pile hole that becomes the trace of the steel pipe. By hardening mortar or ready-mixed concrete or cement milk, concrete piles are built on site.

  When building a cast-in-place concrete pile using this excavated blade-attached steel pipe, the soil and solidified material are not mixed and agitated unlike the conventional columnar improvement method. Therefore, it is possible to build concrete piles for ground reinforcement with stable quality at all times. In addition, there is no worry of toxic substances such as hexavalent chromium eluting depending on the soil.

  When the penetration work is stopped for some reason during the penetration of the steel pipe attached to the drilling blade, the direction opposite to the direction of the excavation rotation at the time of penetration is different from the case where the steel pipe is pulled out by normal concrete pile construction work. Pull out while rotating the steel pipe. By rotating the steel pipe in the direction opposite to the excavation rotation direction, the separation regulating portion of the tip excavation blade is locked to the protrusion of the steel pipe, and the tip excavation blade is also lifted together with the steel pipe. As a result, the tip excavating blade can be reused.

The front Symbol tip digging edge, in contact with the inner peripheral surface of the steel pipe in a state in which the tip digging edge in the steel tube is attached, the tip digging edge of out cylindrical core to center with respect to the steel pipe Is provided.
When the centering portion is provided, the tip excavation blade can be centered with respect to the steel pipe, and rattling of the tip excavation blade can be prevented by the centering portion coming into contact with the inner peripheral surface of the steel pipe. If the centering portion is cylindrical, the gap between the steel pipe and the tip excavation blade is closed, so that soil can be prevented from entering the steel pipe, and a good on-site concrete pile can be built.

The lower end of the front Symbol steel, spiral groove forming blade protruding on the outer circumferential side are provided from the outer peripheral surface of the steel pipe.
When the blade for forming a spiral groove is provided, a spiral groove is formed on the outer periphery of the pile hole when only the steel pipe is extracted after excavating the pile hole with the excavating blade-attached steel pipe. When the excavating blade mounting steel pipe is penetrated into the ground, the spiral groove forming blade body forms a spiral groove opposite to the spiral groove, but the reverse spiral groove is When the steel pipe is pulled out, it is broken and the spiral groove is formed instead. When penetrating the excavating blade mounting steel pipe into the ground, the soil around the pile hole is pushed around by the steel pipe and the ground is compacted. The groove is difficult to collapse.
Thus, by forming a spiral groove on the outer periphery of the pile hole, the mortar or ready concrete or cement milk filled in the steel pipe is not only in the pile hole but also in the spiral groove. Alternatively, cement milk is poured into a spiral knotted concrete pile. When the concrete pile has a spiral knot, the shear resistance of the pile peripheral surface is large. Therefore, the pile peripheral surface resistance force of the concrete pile can be further increased. Large pile surface resistance has the following advantages.
-It is possible to reduce the pile diameter and reduce material costs.
-Less material is required for concrete piles, and environmental load can be reduced.
-Since the tip of the pile can be supported by the ground having a relatively small N value, the pile length can be shortened.
The separation restricting portion extends in a circumferential direction from the rotation receiving portion, and the rotation receiving portion and the separation restricting portion form a hook-like body,
The rotation receiving portion has a trapezoidal cross-sectional shape in which the side surfaces on both sides facing the circumferential direction are hypotenuses, and the both side surfaces face a direction in which the both sides face straightly without being inclined with respect to the surface of the projection of the steel pipe.

Construction method of onsite Concrete system piles of this invention, the digging edge mounting steel pipe, the state in which the tip digging edge is supported so as to be lower, the separation regulating portion protrudes in the rotating receiving part A process of inserting it into the ground while excavating downward with the tip excavating blade, by pushing down while rotating in the excavation rotation direction, which is the direction in which the projection abuts against the surface opposite to the surface on which the mortar or The process of filling the ready-mixed concrete or cement milk, the steel pipe is pulled up while rotating in the excavation rotation direction, the tip excavation blade is separated from the steel pipe, and then the steel pipe is cut by the spiral groove forming blade body. By forming only the steel pipe from the ground while forming a spiral groove in the outer soil, the pile hole that becomes the trace of the steel pipe and the spiral groove And a process of pouring a mortar or ready-mixed concrete or cement milk in the tube.
In this way, when the spiral groove is formed when the steel pipe is drawn, when the drilling blade mounting steel pipe penetrates the ground, the soil around the pile hole is pushed around by the steel pipe and the ground is compacted. The formed spiral groove is difficult to collapse. In the case of this in-situ concrete pile construction method, mortar, ready-mixed concrete or cement milk flows into the spiral groove formed by the spiral groove forming blade body in addition to the pile hole that becomes the trace of the steel pipe. A concrete pile with a knot is built on site.

The excavation blade mounting steel pipe for building a cast-in-place concrete pile with a node according to the present invention includes a steel pipe and a tip excavation blade which is detachably attached to the tip of the steel pipe and has an excavation blade body on the tip surface, Rutotomoni projection is provided which projects the inner diameter side to the inner circumferential surface of the front end of the steel tube, the tip digging edge, said tip abuts on said projection when said steel pipe is rotated in the drilling rotation direction determined around the axis A rotation receiving portion that rotates the excavation blade integrally with the steel pipe, and the tip excavation blade is pivoted with respect to the steel pipe when the steel pipe is pulled up while rotating in the direction opposite to the excavation rotation direction. a separation regulating portion is provided for regulating the separating direction, the tip digging edge, in contact with the inner peripheral surface of the steel pipe in a state in which the tip digging edge in the steel pipe is attached, to the steel pipe Center the tip excavation blade A cylindrical centering portion is provided, and a lower end of the steel pipe is provided with a spiral groove forming blade body projecting outward from the outer peripheral surface of the steel pipe, and the separation restricting portion is the rotation receiving portion. The rotation receiving portion and the separation regulating portion form a hook-like body extending in the circumferential direction from the rotation receiving portion, and the rotation receiving portion has a trapezoidal cross-sectional shape in which both sides facing the circumferential direction are hypotenuses, to construction of the order to face the direction of striking straight without tilting with respect to the surface of the protrusion, the quality without being affected by the state of the site soil stable concrete piles for soil reinforcement of the side surfaces is the steel pipe It is possible to construct concrete piles easily and reliably on site.

Construction method of onsite Concrete system piles of this invention, the digging edge mounting steel pipe, the state in which the tip digging edge is supported so as to be lower, the separation regulating portion protrudes in the rotating receiving part A process of inserting it into the ground while excavating downward with the tip excavating blade, by pushing down while rotating in the excavation rotation direction, which is the direction in which the projection abuts against the surface opposite to the surface on which the mortar or The process of filling the ready-mixed concrete or cement milk, the steel pipe is pulled up while rotating in the excavation rotation direction, the tip excavation blade is separated from the steel pipe, and then the steel pipe is cut by the spiral groove forming blade body. By forming only the steel pipe from the ground while forming a spiral groove in the outer soil, the pile hole that becomes the trace of the steel pipe and the spiral groove It includes the process of pouring mortar or ready-mixed concrete or cement milk in the pipe, so that it is possible to build a knotted concrete pile for ground reinforcement with stable quality without being affected by the soil condition at the site, and concrete It is difficult to collapse the spiral groove of the ground that becomes the node of the system pile, and it is easy to construct on the site, and it is possible to build a concrete system pile with a node reliably.

It is a front view of the excavation blade attachment steel pipe for field casting concrete pile construction concerning one embodiment of this invention. (A) is sectional drawing of the front-end | tip part of the steel pipe of the excavation blade attachment steel pipe, (B) is the side view. (A) is the top view of the front-end | tip excavation blade of the excavation blade attachment steel pipe, (B) is the front view, (C) is the bottom view. It is a perspective view of the tip excavation blade. (A) is the horizontal sectional view which shows one state of the attachment part of the steel pipe of the excavation blade attachment steel pipe and a front-end excavation blade, (B) is VB-VB sectional drawing of FIG. 5 (A). (A) is a horizontal sectional view which shows the state from which the steel pipe of the same excavation blade attachment steel pipe and the attachment part of a front-end excavation blade differ, (B) is VIB-VIB sectional drawing of FIG. 6 (A). It is explanatory drawing of each process of the construction method of the cast-in-place concrete-type pile performed using the excavation blade attachment steel pipe shown in FIG. 1 thru | or FIG. It is explanatory drawing which shows each process of the initial stage when rotating and penetrating the same excavation blade attachment steel pipe into the ground.

  An excavating blade mounting steel pipe for building a cast-in-place concrete pile according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the excavating blade-attached steel pipe 1 includes a steel pipe 10 and a distal excavating blade 20 that is detachably attached to the distal end (lower end in FIG. 1) of the steel pipe 10.

  As shown in FIG. 2, a plurality of (for example, two) or one spiral groove forming blade body 11 projecting from the outer peripheral surface of the steel pipe 10 to the outer peripheral side is provided at the tip of the steel pipe 10. Yes. The spiral groove forming blade 11 has, for example, a cylindrical shape. Block-shaped projections 13 projecting toward the inner diameter side are provided at a plurality of locations (for example, two locations) in the circumferential direction on the inner circumferential surface of the steel pipe 10. Both side surfaces F1 and F2 in the circumferential direction of the block-shaped protrusion 13 are parallel to the axis O1 of the steel pipe 10. In the illustrated example, the axial position of the block-shaped protrusion 13 is substantially the same as that of the spiral groove forming blade 11.

  As shown in FIG. 3 and FIG. 4, the tip excavation blade 20 is composed of an integrally formed product made of steel by casting or forging. The tip digging blade 20 has a digging blade main body 21 having an outer diameter dimension substantially the same as that of the steel pipe 10 and having a cylindrical centering portion 21a that can be fitted into the tip portion of the steel pipe 10 on the opposite end side. The height of the centering part 21a is, for example, about 1 cm. In a state in which the centering portion 21a is fitted in the distal end portion of the steel pipe 10, the distal end surface 14 of the steel pipe 10 is adjacent to the centering portion 21a of the excavating blade body 21 as shown in FIGS. 5 (B) and 6 (B). It contacts the stepped surface 21b. As described above, the centering portion 21a of the tip excavating blade 20 enters and is connected to the steel pipe 10 so that the tip excavating blade 20 is centered with respect to the steel pipe 10, and the steel pipe 10 and the tip excavating blade 20 are aligned. The gap between is closed.

  3 (B) and 3 (C), the distal end surface of the excavating blade body 21 is a conical surface 21c, and two excavating blade bodies 22 are provided on the conical surface 21c. The two digging blade bodies 22 are provided in parallel with the diameter line L adjacent to both sides of the diameter line L passing through the axis O2 of the tip excavation blade 20 respectively. Specifically, one excavation blade body 22 extends from a position on one outer peripheral side in the diametric line direction to an intermediate position between the axis O2 and the other outer peripheral position over the axis O2. ing. The other excavation blade body 22 extends from the position on the other outer peripheral side in the diameter line direction to the intermediate position between the axis O2 and the position on the one outer peripheral side over the axis O2. Yes.

  The outer peripheral side end in the diameter line direction of each excavation blade body 22 is an outer blade portion 22a that protrudes toward the distal end side, and the other end is an inner blade portion 22b that protrudes further toward the distal end side than the outer blade portion 22a. The outer diameter 22a of the outer cutter 22a and the outer outer surface 22ba of the inner cutter 22b are both along the axis O2. Therefore, the front-end | tip of the outer blade part 22a and the inner blade part 22b is formed in an acute angle by front view, and it is easy to bite into the ground. Each digging blade 22 has a certain width in the direction perpendicular to the diameter line L, and the height relative to the digging blade body 20 is the same at any location in the direction perpendicular to the diameter line L.

  Further, as shown in FIGS. 3A, 3B, and 4, the excavation blade main body 21 includes a plurality of (for example, two) hook-like bodies 23 that protrude further toward the tip than the centering portion 21a. Is provided. The hook-like body 23 includes a rotation receiving portion 23a extending from a position on the inner peripheral side of the centering portion 21a of the excavating blade main body 21 to the farther end side than the centering portion 21a, and an opposite end side end of the rotation receiving portion 23a. And a separation restricting portion 23b bent in the circumferential direction. The bending direction of the separation restricting portion 23b is opposite to the excavation rotation direction (A direction) of the steel pipe 10 described later.

  The circumferential side surfaces F3 and F4 of the rotation receiving portion 23a are surfaces facing the circumferential side surfaces F1 and F2 of the projection 13 in a state where the distal excavation blade 20 is attached to the steel pipe 10, respectively. It is parallel to the axis O2 of the excavating blade 20. The cross-sectional shape of the rotation receiving portion 23a is a trapezoid having an inner diameter surface as an upper side and the side surfaces F3 and F4 as hypotenuses, respectively. Further, the surface on the distal end side of the separation restricting portion 23b is a locking surface F5, and this locking surface F5 is on the opposite end side of the protrusion 13 of the steel pipe 20 in a state where the distal excavation blade 20 is attached to the steel pipe 10. Opposite the surface. The side surface F4 and the locking surface 5 of the rotation receiving portion 23a form an obtuse angle. The angle formed by both surfaces F4 and F5 is, for example, about 95 ° (the elevation angle of the locking surface 5 with respect to the surface perpendicular to the axis O2 is about 5 °).

  5 and 6 are cross-sectional views showing different states of the attachment portions of the steel pipe 10 and the tip excavation blade 20 respectively. The tip excavation blade 20 is attached to the steel pipe 10 as follows. That is, the hook-like body 23 of the tip excavating blade 20 is placed in the steel pipe 10 in a state where the tip excavating blade 20 is disposed on the tip side of the steel pipe 10 and the axial centers O1 and O2 of the steel pipe 10 and the tip excavating blade 20 are aligned. This is done by letting It is not necessary to match the circumferential position of the steel pipe 10 and the tip excavation blade 20. For this reason, in order to move the tip head relative to the casing in the axial direction with the axial centers of the casing and the tip head aligned, and with the circumferential phase of the notch and the convex aligned. In comparison, it is easy to install. After the hook-like body 23 has entered the steel pipe 10, the tip excavation blade 20 is rotated around the axis O2 with respect to the steel pipe 10 in a fixed position, and the protrusion 13 of the steel pipe 10 is formed as shown in FIG. If the separation restricting portion 23b is locked, when the excavating blade mounting steel pipe 1 is supported later so that the tip excavating blade 20 is on the lower side, the tip excavating blade 20 is dropped from the steel pipe 10 by its own weight. I can prevent it.

  A method for constructing an in-situ concrete pile using the excavating blade-attached steel pipe 1 for constructing the in-situ concrete pile having this configuration will be described with reference to FIGS.

  First, as shown in FIG. 7 (A), the excavating blade mounting steel pipe 1 is placed on the pile driving device 3 with a rotating mechanism mounted on a work vehicle 2 or the like capable of self-propelling so that the tip excavating blade 20 is on the lower side. Support. The steel pipe 10 of the excavating blade mounting steel pipe 1 may be attached with its upper end fixed to the lifting head 4 of the pile driving device 3. In that case, every time an in-situ concrete pile is built, the tip excavation blade 20 is attached to the tip of the steel pipe 10 in a state of being lifted by the pile driving device 3 by the attaching operation.

  Next, as shown in FIG. 7 (B), the steel pipe 10 is pushed down while rotating in a predetermined excavation rotation direction (A direction), thereby being penetrated into the ground 30 while excavating downward by the tip excavation blade 20 and being pile holes. 31 is formed. At this time, as shown in FIG. 5, the side surface F <b> 1 of the protrusion 13 of the steel pipe 10 contacts the side surface F <b> 3 of the rotation receiving portion 23 a of the tip excavation blade 20, whereby the rotation of the steel pipe 10 is transmitted to the tip excavation blade 20. Since the side surface F1 of the protrusion 13 and the side surface F3 of the rotation receiving portion 23a are parallel to the rotation axes O1 and O2 of the steel pipe 10 and the tip excavation blade 20, the rotation of the steel pipe 10 is smoothly transmitted to the tip excavation blade 20. The Although the regulation separating portion 23b of the tip excavating blade 20 is not locked to the protrusion 13 of the steel pipe 10, the tip excavating blade 20 is pressed against the ground 30, so that the tip excavating blade 20 is separated from the steel pipe 10 in the axial direction. There is nothing. Moreover, since the centering part 21a is provided in the tip excavation blade 20, the tip excavation blade 20 can be centered with respect to the steel pipe 10, and the centering part 21a contacts the inner peripheral surface of the steel pipe 10. Thus, rattling of the tip excavation blade 20 can be prevented. Since the centering portion 21 a is cylindrical, the gap between the steel pipe 10 and the tip excavation blade 20 is closed, and soil does not enter the steel pipe 10.

  When excavating the ground 30 with the respective excavating blades 22, the inner blade portion 22b first bites into the ground 30 as shown in FIGS. 8A and 8B, and then as shown in FIG. 8C. The outer blade 22a bites into the ground 30. Thus, since the inner blade part 22b near the axial center O2 of the tip excavating blade 20 bites into the ground 30 first, the force for swinging the tip part of the excavating blade-attached steel pipe 1 to the side is small. When the outer blade portion 22a bites into the ground 30, a force that swings the tip portion of the excavating blade mounting steel pipe 1 to the side acts, but the diametrical outer surface 22ba along the axis O2 of the inner blade portion 22b has a ground surface. It is firmly engaged with the 30 excavated peripheral surface H1 in the horizontal direction, and this engaging action prevents the swinging movement of the distal end portion of the excavating blade mounting steel pipe 1. Further, since the outer surface 22aa in the diameter line direction of the outer blade portion 22a is also a surface along the axis O2, the outer blade portion once the outer blade surface 22a bites into the ground 30 as shown in FIG. 8D. The outer surface 22aa in the diameter line direction of 22a is engaged with the excavated peripheral surface H2, and the tip of the excavating blade mounting steel pipe 1 is prevented from swinging sideways. In this way, at the initial stage of rotational penetration of the excavating blade-attached steel pipe 1, the tip of the excavating blade-attached steel pipe 1 is prevented from swinging sideways, and the excavating blade-attached steel pipe 1 can be stably penetrated into the ground 30. it can.

  Moreover, in this embodiment, since the front end surface of the excavation blade main body 21 is the conical surface 21c, the excavated soil is guided to the outer peripheral side of the front end excavation blade 20 along the conical surface 21c. Thereby, the excavation blade attachment steel pipe 1 is smoothly penetrated into the ground 30 by rotation penetration. Moreover, the soil excavated by the excavating blade body 22 is guided to the outer peripheral side of the tip excavating blade 20 so that the outer peripheral side of the steel pipe 1 with the excavating blade is densely compressed at the outer peripheral portion of the steel pipe 1 with the excavating blade. As a result, the ground 30 is compacted.

  Next, as shown in FIG. 7C, cement milk S is filled into the steel pipe 20 of the excavating blade-attached steel pipe 1 that has penetrated into the ground 30. Instead of cement milk S, mortar or ready concrete may be filled.

  When the filling of the cement milk S is completed, the steel pipe 10 is pulled out while rotating in the same excavation rotation direction (A direction) as that during penetration. Since the regulation separating portion 23b of the tip excavating blade 20 is not locked to the protrusion 13 of the steel pipe 10, the tip excavating blade 20 is separated from the steel pipe 10 and is left as it is at the bottom of the pile hole 31, and only the steel pipe 10 is pulled out. . Since the protrusion 13 and the separation restricting portion 23b are constantly kept from being locked to each other from the penetration of the steel pipe 10 to the withdrawal, the tip excavation blade 20 is reliably separated from the steel pipe 10.

  When only the steel pipe 10 is pulled out, a spiral groove 32 is formed on the outer periphery of the pile hole 31 by the spiral groove forming blade 11 provided on the outer periphery of the steel pipe 10. When the excavating blade mounting steel pipe 1 penetrates into the ground 30, the spiral groove forming blade body 11 forms a spiral groove opposite to the spiral groove 32. The groove is broken when the steel pipe 10 is pulled out, and the spiral groove 32 is formed instead. When the excavating blade-attached steel pipe 1 is penetrated, the soil corresponding to the volume of the excavating blade-attached steel pipe 1 is pushed around and the ground 30 is compacted. Therefore, when the spiral groove 32 is formed when the steel pipe 10 is pulled out, it is formed. The spiral groove 32 is difficult to collapse.

  As shown in FIG. 7D, by extracting only the steel pipe 10 from the ground 30, the cement milk S in the steel pipe 10 flows into the pile hole 31 and the spiral groove 32 that are traces of the steel pipe 10. The cement milk S in the pile hole 31 may be compacted using a vibrator or the like. If the steel pipe 10 is completely pulled out, the pile head Sa of the cement milk S is smoothed out. This completes the construction. When the cement milk S is hardened, the cast-in-place concrete pile 33 with a node is formed.

  The cast-in-place concrete pile 33 has a spiral node on the outer periphery of the columnar pile body, and the spiral node bites into the ground 30. Moreover, since the ground 30 is compacted at the time of penetration of the excavation blade attachment steel pipe 1, the shear resistance of a pile surrounding surface is large.

When the pile peripheral surface resistance of the in-situ concrete pile 33 is large, the following advantages are obtained.
-It is possible to reduce the pile diameter and reduce material costs.
-The material for the on-site concrete pile 33 can be reduced, and the environmental load can be reduced.
-Since the tip of the pile can be supported by the ground having a relatively small N value, the pile length can be shortened.

  The construction method of the cast-in-place concrete pile using this excavating blade-attached steel pipe 1 does not mix and agitate the soil and solidified material in the field unlike the conventional columnar improvement method. Therefore, it is possible to build concrete piles for ground reinforcement with stable quality at all times. In addition, there is no worry of toxic substances such as hexavalent chromium eluting depending on the soil. Furthermore, since the soil around the pile hole is pushed around by the steel pipe and the ground is compacted, the pile surface resistance force of the concrete pile can be increased.

  When the penetration work is stopped for some reason during the penetration of the excavating blade-attached steel pipe 1 into the ground 30, unlike the case where the steel pipe 10 is pulled out by a normal concrete pile construction work, the anti-excavation rotation direction (anti-A The steel pipe 10 is pulled out while rotating in the direction). By rotating the steel pipe 10 in the direction opposite to the excavation rotation direction, the separation restricting portion 23b of the tip excavation blade 20 is engaged with the protrusion 13 of the steel pipe 10, and the tip excavation blade 20 is pulled up together with the steel pipe 10. Thereby, the tip excavation blade 20 can be reused. During reverse rotation, the side surface F4 of the rotation receiving portion 23a of the tip excavating blade 20 is in contact with the side surface F2 of the protrusion 13 of the steel pipe 10 as shown in FIG.

In summary, the excavating blade-attached steel pipe 1 has the following effects when the tip excavating blade 20 having the above configuration is detachably attached to the tip of the steel pipe 10.
A predetermined pile diameter can be secured by the tip excavation blade 20.
-The tip support force can be secured by the tip excavation blade 20.
The tip excavation blade 20 can be smoothly attached to and detached from the steel pipe 10 without matching the circumferential positions of the steel pipe 10 and the tip excavation blade 20.
-By providing the tip excavating blade 20 with the centering part 21a fitted to the tip of the steel pipe 10, it is possible to prevent the soil from entering the steel pipe 10 during the rotation penetration.
-By providing the centering part 21a, the tip excavation blade 20 can be stably attached to the steel pipe 10.
The tip excavating blade 20 can be pulled up together with the steel pipe 10 and the tip excavating blade 20 can be collected by rotating the excavating blade-attached steel pipe 1 in the direction opposite to that during rotation penetration.

DESCRIPTION OF SYMBOLS 1 ... Excavation blade attachment steel pipe 10 ... Steel pipe 11 ... Spiral groove forming blade 13 ... Protrusion 20 ... Tip excavation blade 21a ... Centering part 22 ... Excavation blade 23 ... Hook-like body 23a ... Rotation receiving part 23b ... Separation Restriction part 30 ... Ground 31 ... Pile hole 32 ... Spiral groove 33 ... In-situ concrete pile S ... Cement milk

Claims (2)

And steel pipes, detachably attached to the tip of the steel pipe becomes at the tip digging edge having an excavating blade to the tip surface, the projections projecting into the inner diameter side is provided on the inner peripheral surface of the distal end of said steel tube Rutotomoni The tip excavating blade has a rotation receiving portion for rotating the tip excavating blade integrally with the steel pipe in contact with the protrusion when the steel pipe rotates in the excavation rotation direction defined around the axis; and A separation restricting portion is provided that locks on the protrusion when pulling up while rotating in the direction opposite to the excavation rotation direction and restricts the tip excavation blade from separating in the axial direction from the steel pipe,
The tip excavating blade is provided with a cylindrical centering portion that abuts the inner peripheral surface of the steel pipe in a state where the tip excavating blade is attached to the steel pipe and centers the tip excavating blade with respect to the steel pipe. And
The lower end of the steel pipe is provided with a spiral groove forming blade body projecting to the outer peripheral side from the outer peripheral surface of the steel pipe,
The separation restricting portion extends in a circumferential direction from the rotation receiving portion, and the rotation receiving portion and the separation restricting portion form a hook-like body,
The rotation receiving portion has a trapezoidal cross-sectional shape in which both side surfaces facing the circumferential direction are hypotenuses, and the both side surfaces are directed in a straight direction without being inclined with respect to the surface of the projection of the steel pipe. Excavation blade mounting steel pipe for construction of steel piles. A construction method of a cast-in-place concrete pile using the excavation blade mounting steel pipe for concrete pile construction according to claim 1 ,
In a state in which the excavation blade mounting steel pipe is supported so that the tip excavation blade is on the lower side, the projection comes into contact with the surface of the rotation receiving portion opposite to the side on which the separation restricting portion protrudes. The process of inserting into the ground while excavating downward by the tip excavation blade by pushing down while rotating in a certain excavation rotation direction;
Filling the steel pipe with mortar, ready-mixed concrete, or cement milk, and pulling up the steel pipe while rotating in the excavation rotation direction to separate the tip excavation blade from the steel pipe, and then forming the spiral groove While forming a spiral groove in the soil around the outer periphery of the steel pipe with a blade body, by pulling out only the steel pipe from the ground, a mortar in the steel pipe is formed in the pile hole and the spiral groove that are traces of the steel pipe Or the process of pouring ready-mixed concrete or cement milk,
On-site concrete piles including

Images