JP3510988B2 - Steel pipe pile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foundation pile for a building, and more particularly to a steel pipe pile most suitable for a structure requiring a horizontal force or a pulling force.

[0002]

2. Description of the Related Art Conventionally, the method of burying foundation piles is a hammering method in which a pile is driven into the ground by a hammer using a diesel hammer or the like, but today, from the viewpoint of environmental conservation, generation of noise and vibration is suppressed. the method of construction, namely Chuho method utilizing the inner diameter of the pile, construction method was a combination of cormorant _Wow ter jet method,
Alternatively, a cement milk method or the like in which a liquid material such as cement or bentonite is injected into a hole excavated by an earth auger and a pile is inserted into the liquid material and fixed therein is used.

[0003]

The loads acting on a pile include a vertical load, a horizontal load, and a pull-out load. And the sum of the peripheral frictional forces of the piles. Among them, the function of the pile peripheral friction force greatly exceeds the pile tip supporting force. In other words, it is not an exaggeration to say that the support performance of the pile is based on the peripheral frictional force of the pile.

[0004] Among the above-mentioned supporting forces, the tip supporting force does not vary according to the material of the pile used, but the frictional force on the peripheral surface of the pile largely depends on the material. The frictional force at the contacting part is small, and it tends to be inferior to the frictional force of cast-in-place concrete piles even when viewed as a whole pile.

[0005] Therefore, in steel pipe piles, a method has been devised in which the soil around the pile surface is soiled using cement milk or the like to enhance the frictional force on the pile peripheral surface. At present, it is impossible to break this wall due to frictional factors caused by the material as compared with cast-in-place concrete piles. In addition, the properties of the ground subject to construction are gravel,
It is usually formed by each layer of clay, silt, etc., and even when the whole ground is formed of sand, the hardness, softness and strength are never uniform due to the difference in properties of the sand having a plurality of layers. As described above, the fact that the ground is not uniform means that the degree of expression of the frictional force in each layer is different, and the frictional force of the pile installed in such a place greatly varies, so that the effective ground on the pile peripheral surface is effective. The load cannot be transmitted.

[0006] Therefore, the cement milk method is used. One method is to inject cement milk into the soil to soil the ground, form an improved body, and bury the pile there. The other is to excavate and discharge the soil, then inject and replace the cement milk to form a cement milk column (improved body), bury the pile there, and uniformly transmit the load acting on the pile to the ground. The method has been adopted. However, even if the quality of the improved body is uniform, if a load such as vertical, horizontal or pulling acts on the hardened pile of the improved body, the amount of elastic displacement due to the difference in physical properties between the pile and the improved body Due to the change in stress, the stress from the load concentrates on the improved body, the improved body is greatly deformed, the uniform load is not transmitted to the pile surrounding ground, and the true force originally held by the ground is sufficiently Was not fully utilized.

In view of the above problems, an object of the present invention is to provide a steel pipe pile which can exert a large vertical supporting force, a horizontal force, and a pulling force.

[0008]

In order to achieve the above object, the present invention relates to a steel pipe pile having a through-hole at a tip end face and inserted into a drilling hole filled with an improved body to form a composite pile. A spiral excavating wing having approximately one half of the outer circumference of the hollow metal cylinder as one unit is provided at a position facing each other at a position of approximately 25 degrees with respect to the axial direction of the metal cylinder. In the overlapped state, the phases are shifted with respect to the rotation direction, and the edge portions are provided in two-stage overlap so that projections in the axial direction form a perfect circle without interruption. multiple set only with a predetermined interval along the entire length of approximately 10% and the result together with a diameter of the excavation wingspan said metal tube
The opening ratio of the through hole to the tip end surface is 10 to 20%.
And said that the content was.

[0009]

[0010]

Since the Great Hanshin-Awaji Earthquake, piles have been required to have strong seismic resistance. The mechanism of the frictional resistance of the pile surface is based on the load acting on the pile and the adhesive force between the pile and the improved body. As the load increases, it acts as a shearing force between the soil and the soil via the improved body, and this acts as a frictional force around the pile surface. Therefore, in order to surely obtain a large pile peripheral friction force, the relationship between the adhesive force and the shear force must be firmly linked. In this regard, the configuration in which the pile of the present invention is provided with multiple and multiple ring-shaped excavating wings plays a role of this connection. FIGS. 8A and 8B are explanatory diagrams showing such a stress relationship. FIG. 8A shows a frictional force against a vertical load, FIG. 8B shows a frictional force against a pull-out load, FIG. 8C shows a frictional force against a horizontal load, and FIG. The transition from the adhesive force or the pulling force to the shearing force is shown, 1 is a steel pipe pile, and 4 is a drilling wing.

[0012] For example, an improved body which has been soild by injecting a ground hardening material such as cement milk, or an improved body obtained by replacing soil with cement milk is constrained by excavating wings at a plurality of upper and lower locations, thereby forming a pile and Due to the large adhesive force generated between the improved body and the improved body, the improved body does not peel off, and is reliably transmitted as a shear force to the ground around the improved body. In addition, even when the construction is carried out on ground with uneven properties, the effect of restraining the improved body with the excavating wing can increase the adhesion of the improved body, so the load on the pile is surely applied to the ground around the pile. As a result, the natural shear force of the soil can be obtained to the maximum and the uniform and strong pile circumferential friction can be exerted. The steel pipe pile of the present invention has strong earthquake resistance and sufficiently satisfies the above requirements.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a side view and a perspective explanatory view of a steel pipe pile according to the present invention, FIG. 2 is an exploded view of the tip, and FIG. 3 is a sectional view taken along the line AA of FIG.

The metal tube 1a, which is the main body of the steel pipe pile 1, is provided with a cover plate 3 having a through hole 3a formed at the center thereof, and a semi-ring shape having a unit corresponding to a substantially half circumference. Are spirally provided at positions opposing each other as a set of two pieces with a phase shift with respect to the rotation direction of the metal cylinder 1a. The span T of each excavation wing 4 is approximately 1 of the metal cylinder diameter D.
0%, and is formed so as to protrude in a direction orthogonal to the axial direction of the metal cylinder 1a. The mounting of the excavation wings 4 can be performed by, for example, arc welding. The opposing excavating wings overlap each other by about 25 degrees with respect to the axial direction of the metal cylinder 1a, and are provided in two vertical stages, and the projection in the axial direction is a perfect circle without any break. The set of excavating wings 4 is attached at a constant interval over the entire length of the metal cylinder 1a, for example, at an interval of about twice the cylinder diameter.

The through hole 3a of the cover plate 3 is formed in a size that allows the improved body to enter from below, as described later. Further, the width and the overlap angle of the excavation wing 4 need not be 10% or 25 degrees of the cylinder diameter, but if the width is about 10%, the metal cylinder 1
a, for example, even if the diameter of the entire steel pipe pile is φ60 cm, the main body can be made as thick as φ50 cm, the rigidity of the steel pipe pile can be kept high, and the excavating wing having a width of 5 cm is strong with the improved body. To join. In addition, by providing the overlap at about 25 degrees, the screwing into the excavation hole can be performed smoothly, and the ground solidification material can be stirred. Further, when projected in the axial direction, the set of excavating wings can be regarded as one ring body, so that the solidified improved body can be securely restrained.

Next, a method of burying the steel pipe pile 1 will be described with reference to FIG. FIG. 4 is an explanatory view showing the embedding procedure. First, as shown in FIG. 4A, excavation is performed until the soil reaches the support ground 9 while discharging cement milk as a ground solidifying material from the tip of the screw 7 of the earth auger 6. After reaching the support ground, the screw 7 is moved up and down several times near the support ground to sufficiently knead the support ground and the cement milk. The excavated hole is filled with cement milk kneaded with soil, i.e., the improved body 10. Alternatively, it is filled with the improved body 10 injected with cement milk after being excavated and discharged by the earth auger 6. This state is (b).

Thereafter, before the improved body 10 is hardened, the steel pipe pile 1 is inserted while rotating (shown in FIG. 1C). In this step, the improved body 10 tends to move upward while being further kneaded by the rotating operation of the excavating wing 4, but as shown in the cross-sectional view of the tip of the steel pipe pile 1 in FIG. Through 3a, it also flows into the inside of the steel pipe pile 1. As a result, the improved body 10 before hardening does not overflow to the ground, and is filled into the pile peripheral surface and the inside of the pile with the insertion of the steel pipe pile 1, thereby further increasing the rigidity of the steel pipe pile 1.

Then, it cures over time, and (d)
As shown in the figure, the improved body 10 is firmly integrated with the steel pipe pile 1,
It can be seen that a composite pile having a steel pipe pile as a core material was formed. FIG. 6 is an image diagram showing a state in which the improved body 10 and the steel pipe pile 1 are integrated, and the improved body 12 solidified as shown in this figure is more firmly formed by the ring-shaped partition walls 13 formed by the excavating wings 4. Is blocked by the improved body 12
Are tightly coupled with the steel pipe pile 1 and integrated.

As described above, by providing the spiral and ring-shaped sets of excavating wings 4 in multiple stages, when the steel pipe pile 1 is rotated, the mixing action is performed, and the soil on the pile peripheral surface and the cement milk are removed. Can be sufficiently kneaded, and at the end of the burial of the pile, a composite pile having a diameter consisting of a layer formed of a steel pipe pile plus an improved body of good quality and uniform thickness can be formed. This load is reliably transmitted to the ground surrounding the pile, and while obtaining the original shear force of the soil to the maximum, it is possible to exert a uniform and strong pile peripheral frictional force, Horizontal force and pull-out force can be exerted greatly. Still further, the excavation wing just serves as a spacer, so that when the pile is inserted, the pile can be accurately positioned.

In this embodiment, it is described that the steel pipe pile 1 is inserted while rotating it. However, it is possible to insert the steel pipe pile 1 without rotating it as long as the improved body is a liquid. Any construction method may be adopted as long as it is installed in a state as shown in FIG. In addition, the shape of the through hole of the pile tip cover plate 3 is not only formed at the center of the cover plate as shown in FIG. 7A, but also provided with a plurality of circular through holes 15 as shown in FIG. Alternatively, as shown in FIG. 7 (c), the shape may be such that an oval hole 16 is provided in accordance with the rotation direction.
If the opening ratio is about 10 to 20% of the pile tip diameter, pile characteristics equivalent to those of a completely closed pile can be obtained.

Further, in the above-described embodiment, a cover plate having a through-hole is merely provided at the end portion, but a bit capable of excavation may be provided at a position where the through-hole is not closed. Further, with respect to the adjustment of the curing speed of the improved body, a fluidization accelerator, a solidification retarder, or the like may be mixed in accordance with the change in the excavation depth or ground properties.

[0022]

As described above in detail, according to the first aspect of the present invention, a plurality of sets of excavating wings which are spirally formed on the side and have a width of about 10% of the cylinder diameter are provided. Therefore, if it is buried in the excavation hole into which the ground hardening material such as cement milk has been injected and hardened, the excavation wing acts as a connecting material to restrain the hardened material and acts like an integrated pile as a whole. I do. Therefore, the stress such as the load applied to the steel pipe pile is transmitted to the ground around the pile, and a strong pile peripheral friction force can be exerted, so that the vertical support force, the horizontal force, and the pulling force can be largely exerted. In addition, since the amount of protrusion of the excavation wing is relatively small, approximately 10% of the diameter of the cylinder, the thickness of the metal cylinder can be made sufficiently large with respect to the diameter of the borehole, and the rigidity of the steel pipe pile can be maintained high. Can be. Furthermore, the excavating wings provided at a plurality of locations just serve as spacers, and when the pile is inserted into the excavation hole, the pile can be accurately positioned. In addition, since the overlap angle of the excavation wing is set to about 25 degrees, it is possible to smoothly screw into the excavation hole and to agitate the ground solidified material. Further, when it reaches the bottom in the axial direction, the set of excavation wings can be regarded as one ring body, so that the solidified improved body can be securely restrained. Sa
In addition, a through-hole with an opening ratio of 10 to 20% is provided
Excavation of steel pipe piles by injecting ground consolidation material
When buried in the hole, the ground hardening material passes through the
It also flows inside. Therefore, at the time of burial,
Without spilling over the ground, burying steel pipe piles and pile surroundings and piles
Filled inside to further increase the rigidity of the steel pipe pile
You. Further, the opening ratio of the through hole to the tip surface is 10 to 2
Because it is 0%, obtain pile characteristics equivalent to a completely closed pile
Can be.

[0023]

[0024]

[Brief description of the drawings]

FIG. 1 shows an example of an embodiment of a steel pipe pile according to the present invention, in which (a) is a side view, and (b) is an enlarged perspective view of a part.

FIG. 2 is an exploded explanatory view of a distal end portion of FIG.

FIG. 3 is a sectional view taken along the line AA of FIG. 1;

4A and 4B are side views for explaining a burial step of the steel pipe pile of FIG. 1, wherein FIG. 4A is a digging step, FIG. 4B is a state of a hole filled with a ground solidification material after digging, and FIG. Inserting,
(D) has shown the state after steel pipe pile insertion.

FIG. 5 is an explanatory cross-sectional view showing the state of the tip of the steel pipe pile in the state of FIG. 4 (c).

6 is an image diagram of a composite pile newly formed by the process of FIG. 4;

FIG. 7 is a view showing the shape of a lid plate at the tip of a steel pipe pile.

8A and 8B are explanatory diagrams of stress applied to a load acting on the steel pipe pile shown in FIG. 1, wherein FIG. 8A is a friction force applied to a vertical load, FIG. 8B is a friction force applied to a pull-out load, FIG. (D) shows the transition from the adhesive force or the pulling force to the shearing force.

[Explanation of symbols]

1 .... steel pipe pile, 1a ... metal cylinder (body), 3 .... lid plate,
3a: Through hole, 4: Drilling wing.

Claims (1)

(57) [Claims] Claims 1. A steel pipe pile having a through hole formed in a tip end face and inserted into a drilling hole filled with an improved body to form a composite pile, wherein approximately half the circumference of the hollow metal cylinder is provided around the outer circumference of the hollow metal cylinder. The spiral excavating wings as one unit are shifted in phase with respect to the rotation direction in a state where two sets of the spiral excavating wings overlap each other at approximately 25 degrees with respect to the axial direction of the metal cylinder. and an edge portions provided at two-tiered so that circularity unbroken projection with respect to the axial direction, a plurality set only the set of the excavation blade with a predetermined interval along the entire length of the metal tube, the The excavation wing width is set to approximately 10% of the diameter of the metal cylinder ,
A steel pipe pile having an opening ratio with respect to the tip end surface of the through hole of 10 to 20% .