JP2014062363A - Steel pipe pile and construction method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel pipe pile that can have the base protected to sufficient strength and secure high reliability in a clay layer and a gravel layer, and a construction method thereof.SOLUTION: A cap (13) having an insertion hole (13A) is fixed to a rear end opening of a hollow steel pipe, a plurality of belt-like leg parts (12A) in a diameter-increased attitude having mutually intervals increased toward tips are formed at a tip part, and the belt-like leg parts are reduced in diameter into a diameter-decreased attitude having the mutual intervals made narrower toward the tips as compared with the diameter-increased attitude and externally fitted with a sleeve (14) to be held in the diameter-decreased attitude. A shock reception part (15) is fixed to the sleeve, and when a shock is given to the shock reception part, the sleeve is detached from the belt-like leg parts, which restore themselves into the diameter-increased attitude with elastic restoring force thereof.

Description

  The present invention relates to a steel pipe pile and a construction method thereof, and more particularly, to a pile and a method capable of solidifying with sufficient strength and ensuring high reliability even in a clay layer and a gravel layer.

  When building a building structure, a steel pipe pile is driven into the ground, and a steel pipe pile is used as a foundation of a building structure by fixing a reinforcing bar to the steel pipe pile.

  In the steel pipe pile mentioned above, a pile hole is excavated in the ground with an auger screw etc., the diameter of the bottom of the pile hole is expanded, and the expanded diameter part is filled with cement milk, and a hollow steel pipe is inserted into the cement and integrated. A cement filling method is known (Patent Document 1).

Japanese Patent Laid-Open No. 2001-234531

  However, in the steel pipe pile described in Patent Document 1, the tip of the steel pipe is simply inserted and hardened into the cement enlarged portion, so that the cement enlarged portion is small, and the cement enlarged portion and the steel pipe tip are Bonding is not sufficient and sufficient strength cannot be solidified, especially in the case of clay and gravel layers, the reliability of steel pipe piles may be low.

  In view of such problems, the present invention is to provide a steel pipe pile that can be solidified with sufficient strength and that can guarantee high reliability even in a clay layer or a gravel layer, and a construction method thereof. And

  Therefore, the steel pipe pile according to the present invention has a plurality of strip-shaped legs in which a cap having an insertion hole is fixed to the rear end opening of the hollow steel pipe, and the distal end portion has a diameter-expanding posture in which a mutual interval is widened toward the front end. The band-shaped leg portions are held in the above-mentioned reduced diameter posture by being contracted to a reduced diameter posture in which the distance between them is narrowed toward the tip as compared with the enlarged diameter posture, and the sleeve is externally fitted. An impact receiving portion is fixed to the sleeve, and when the impact is applied to the impact receiving portion, the sleeve is detached from the belt-like leg portion, and the belt-like leg portion is expanded by its elastic restoring force. It is characterized by being restored.

  One of the features of the present invention is that the rear end opening of the hollow steel pipe is sealed with a cap to form a plurality of strip-shaped leg portions having an enlarged diameter at the tip portion, the plurality of strip-shaped leg portions are reduced in diameter, and the sleeve is externally fitted. When the sleeve is removed and the sleeve is detached, the plurality of belt-like leg portions are restored to the diameter-expanded posture.

  As a result, an enlarged diameter portion is formed at the bottom of the pile hole, and when the steel pipe pile is inserted and the sleeve is detached, the belt-like leg portion is enlarged, and when the cement milk is press-fitted into the steel pipe pile from the insertion hole of the cap, When the diameter of the leg portion is further expanded by the pressure of the cement milk and the cement milk is solidified in this state, it can be combined with the belt-like leg portion of the steel pipe pile to form a cement expanded diameter root portion.

  Since this band-shaped leg is in a state where the diameter-expanding posture is further expanded by the pressure of cement milk, a large cement-expanded root can be formed, and the band-shaped leg is coupled to the cement-expanded root and strengthened, The pile can be sufficiently solidified. For example, in a clay layer or a gravel layer, even if an upward pulling force or a shaking force to the left and right is applied, high reliability of the steel pipe pile can be ensured.

  The steel pipe pile needs to form a strip-shaped leg portion having an expanded posture having an elastic restoring force at the tip portion of the hollow steel pipe, but it is difficult to form the strip-shaped leg portion having such a shape by cutting or the like. Therefore, a plurality of slits are formed at the tip of the steel pipe to form strip-shaped leg portions, these strip-shaped leg portions are bent into a diameter-expanded posture, held in that posture with a jig, etc., depending on the material of the steel pipe When heat treatment (quenching and tempering) under the above conditions is performed, the belt-like leg portion can be held in an expanded posture, and elasticity can be imparted to the belt-like leg portion.

  Moreover, in order to perform the above heat treatment on a long steel pipe, a large heat treatment furnace is required. Therefore, the hollow steel pipe is composed of a hollow steel pipe main body and a hollow tip steel pipe fixed to the hollow steel pipe body, and the strip-like leg portion of the tip steel pipe is bent into a diameter-expanded posture and is heat-treated to be held in the diameter-expanded posture. By doing so, heat treatment can be performed in a small heat treatment furnace.

  According to the present invention, a cap having an insertion hole is fixed to the rear end opening of a hollow steel pipe, and a plurality of strip-shaped leg portions having a diameter-enlarging posture in which the distance between the caps is widened toward the distal end are formed. The legs are held in the reduced diameter posture by reducing the diameter of the legs to a reduced diameter posture in which the distance between the legs is narrowed toward the tip compared to the enlarged diameter posture, and the impact receiving portion is fixed to the sleeve. The steel pipe pile is used to excavate a pile hole in the ground with an excavator, and an enlarged diameter part is formed at the bottom of the pile hole, and the steel pipe pile is inserted into the pile hole to reach the bottom of the pile hole. Before, by applying a downward impact to the impact receiving portion of the steel pipe pile, the sleeve is detached from the belt-like leg portion, and the belt-like leg portion is restored to an expanded posture by its elastic restoring force, and the insertion of the cap Cement milk is pressed into the hollow steel pipe from the hole. The strip-shaped leg portion in the above-mentioned diameter-expanding posture is further expanded in diameter, and cement milk is solidified in that state to form a cement-expanded root portion coupled with the strip-shaped leg portion of the hollow steel pipe. The construction method of a steel pipe pile can be provided.

  Here, the downward impact to the impact receiving portion may be performed by dropping a metal ball set in the hollow steel pipe, and the downward impact to the impact receiving portion is given by a push rod inserted from the insertion hole of the cap. You may do it.

It is a figure which shows the whole structure in the preferable embodiment of the steel pipe pile which concerns on this invention, a front-end | tip steel pipe, and an impact receiving part. It is a figure which shows typically the construction method of the said steel pipe pile. It is a figure which shows the steel pipe pile constructed by the said construction method. It is a figure which shows 2nd Embodiment typically.

  1 to 3 show a preferred embodiment of a steel pipe pile according to the present invention. In the figure, a steel pipe pile 10 is composed of a hollow steel pipe main body 11 and a hollow tip steel pipe 12. A cap 13 is fixed to the rear end (upper end) opening of the steel pipe main body 11 by welding, and is inserted into the center of the cap 13. A hole 13A is formed, and a metal ball 19 is suspended and set in the rear end portion of the steel pipe main body 11 by a wire 19A.

  The tip steel pipe 12 has a groove 12B formed at the rear end thereof, and is fixed by being abutted against the groove at the tip of the steel pipe main body 11 and being welded (in the figure, 17 is a welded portion). The plurality of slit-like legs 12A are formed by forming the plurality of slits 12C at equal intervals with substantially the same width from the tip toward the rear.

  As shown in FIG. 1B, the plurality of strip-shaped leg portions 12A are bent into a diameter-enlarged posture in which the distance between the strip-shaped leg portions 12A is increased toward the tip, and are subjected to quenching and tempering to obtain a diameter-expanded posture. While being held, springiness is imparted. The quenching and tempering conditions are selected according to the material of the tip steel pipe 12.

  Further, the plurality of belt-like leg portions 12 are deformed from a diameter-expanded posture to a reduced-diameter posture in which the mutual distance becomes narrower toward the tip or equal to each other than the enlarged-diameter attitude, and is cylindrical. The sleeve 14 is externally fitted to maintain the reduced diameter posture. A groove is formed at the tip of the sleeve 14 and is fixed by being abutted and welded to the impact receiving portion 15 (in the figure, 18 is a welded portion). The belt-shaped leg portion 12 </ b> A having a reduced diameter is formed between the sleeve 14 and the pressing portion 15 </ b> A.

  When the steel pipe pile 10 is driven into the ground 50, as shown in FIG. 2 (a), when the pile hole 51 is excavated by the auger screw 20 and reaches a predetermined depth, it is shown in FIG. 2 (b). As described above, for example, water is sprayed around the tip of the auger screw 20 to form the enlarged diameter portion 52.

  Next, the auger screw 20 is pulled out from the pile hole 51, and the steel pipe pile 10 of this example is inserted into the pile hole 51 as shown in FIG. When a predetermined distance is reached from the bottom surface, the wire 19A is loosened and the metal ball 19 is dropped to collide with the holding portion 15A of the impact receiving portion 15, and a downward impact is applied to the impact receiving portion 15 to reduce the sleeve 14 in a reduced diameter posture. 2A, the belt-like leg portion 12A is restored from the reduced diameter posture to the enlarged diameter posture by its elastic restoring force as shown in FIG. 2 (d).

  Therefore, when the cement milk 30 is press-fitted from the insertion hole 13A of the cap 13, the belt-like leg portion 12A receives the pressure of the cement milk and is further expanded from the expanded posture, and when the cement milk solidifies in this state, FIG. As shown, a large-diameter enlarged root 31 is formed at the base of the steel pipe pile 10.

  The solidified cement is firmly bonded to the strip-shaped leg portion 12A of the steel pipe pile 10 having a large diameter, and can form a large cement-expanded root portion 31 to firmly solidify the steel pipe pile 10. For example, a clay layer Even in the gravel layer or the gravel layer, even if an upward pulling force or a shaking force to the left and right is applied, the high reliability of the steel pipe pile 10 can be guaranteed.

  FIG. 4 shows a second embodiment, in which the same reference numerals as those in FIGS. 1 to 3 denote the same or corresponding parts. In this example, the push rod 40 is pushed in from the insertion hole 13A of the cap 13 in place of the metal ball, while the backing 41 is welded to the welded portion 17 between the steel pipe main body 11 and the tip steel pipe 12, and the impact receiving portion 15 is used. Is formed in a hemispherical shape.

  In the steel pipe pile of this example, as in the first embodiment, after excavating the pile hole and inserting the steel pipe pile, the push rod 40 is inserted from the insertion hole 13A of the cap 13 and the impact receiving portion 15 is given a downward impact. Then, the sleeve 14 is detached from the belt-like leg portion 12 </ b> A, the push rod 40 is pulled out, and cement milk may be press-fitted from the insertion hole 13 </ b> A of the cap 13.

DESCRIPTION OF SYMBOLS 10 Steel pipe pile 11 Steel pipe main body 12 Tip rear end 12A Band-shaped leg part 13 Cap 13A Insertion hole 14 Sleeve 15 Impact receiving part 19 Metal ball 30 Cement milk 31 Cement expanded root part 40 Push rod 50 Ground 51 Pile hole

Claims (6)

A cap (13) having an insertion hole (13A) is fixed to the rear end opening of the hollow steel pipe, and a plurality of strip-shaped leg portions (12A) having a diameter-enlarging posture in which the distance between the ends is increased toward the tip. The belt-like leg portion (12A) is reduced in diameter to a reduced diameter posture in which the distance between the leg portions (12A) is narrowed toward the tip as compared with the enlarged diameter posture, and the sleeve (14) is externally fitted to reduce the above-mentioned contraction. It is held in a radial posture, and an impact receiving portion (15) is fixed to the sleeve (14),
When the impact is applied to the impact receiving portion (15), the sleeve (14) is detached from the belt-like leg portion (12A), and the belt-like leg portion (12A) is restored to an expanded posture by its elastic restoring force. A steel pipe pile characterized by that.   The said hollow steel pipe is comprised from the hollow steel pipe main body (11) and the hollow front-end | tip steel pipe (12) fixed to this, The diameter expansion attitude | position which extended the mutual space | interval toward this front-end | tip steel pipe (12) toward the front-end | tip. The steel pipe pile according to claim 1, wherein a plurality of belt-like legs (12A) are formed.   The steel pipe pile according to claim 1, wherein the belt-like leg portion (12A) of the tip steel pipe (12) is held in an expanded posture by being bent and heat-treated in an expanded posture. A cap (13) having an insertion hole (13A) is fixed to the rear end opening of the hollow steel pipe, and a plurality of belt-like leg portions (12A) are formed at the distal end portion so as to have a diameter-enlarging posture with the mutual distance being expanded toward the distal end. Then, the belt-like leg portion (12A) is reduced in diameter to a reduced diameter posture in which the distance between the strip legs (12A) is narrowed toward the tip, and the sleeve (14) is externally fitted to the reduced diameter posture. Using a steel pipe pile (10) formed by holding and fixing the impact receiving portion (15) to the sleeve (14),
While excavating the pile hole (51) vertically in the ground (50) with the excavator (20), forming the enlarged diameter part (52) at the bottom of the pile hole (51),
Insert the steel pipe pile (10) into the pile hole (51),
Before reaching the bottom of the pile hole (51), the sleeve (14) is detached from the belt-like leg (12A) by applying a downward impact to the impact receiving part (15) of the steel pipe pile (10). The belt-like leg (12A) is restored to its expanded posture by its elastic restoring force,
Cement milk (30) is press-fitted into the hollow steel pipe from the insertion hole (13A) of the cap (13) to further expand the diameter of the strip-shaped leg portion (12A) in the expanded diameter posture. ) Is solidified to form a cement expanded diameter root portion (31) combined with the hollow steel pipe.   The construction method of a steel pipe pile according to claim 2, wherein the downward impact to the impact receiving portion (15) is performed by dropping a metal ball (19) set in the hollow steel pipe.   The construction method of a steel pipe pile according to claim 2, wherein a downward impact on the impact receiving portion (15) is given by a push rod (40) inserted from an insertion hole of a cap.

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