JP2002061173A - Precast pile with enlarged head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deformed precast pile with an enlarged head having a small-diameter lower pile body integrally connected to the upper end of a large-diameter upper pile body, particularly assuring firm junction of these and achieving economical mass production with no waste and a lighter weight. SOLUTION: The precast pile with the enlarged head comprises a joint steel material 4 having a downward taper 8 on the lower outer periphery with its lower end 13 rounded and having a thickness (a) at a portion to be in contact with the small-diameter lower pile body 3, laid between the large-diameter upper pile body 2 and the small-diameter lower pile body 3, and ring notched grooves 9 provided in the outer periphery junction parts thereof, the ring notched groves 9 being subjected to welding 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is economical without increasing the number of piles or increasing the diameter of piles even when a large horizontal force or bending moment acts on the pile head from the upper structure. The upper part which can correspond is related to the enlarged prefabricated pile with the upper part having a large diameter and the lower part having a small diameter. In particular, the large-diameter upper pile body and the small-diameter lower pile body are interconnected via a joint steel material having a predetermined thickness. This is related to the expanded prefabricated pile.

[0002]

2. Description of the Related Art Conventionally, known techniques relating to a head expansion pile are disclosed in, for example, Japanese Utility Model Publication No. Sho 63-2509 (first known technique), Japanese Patent Laid-Open Publication No. 52-7109 (second known technique), and Japanese Patent Laid-Open Publication No. 58-58.
-27366 (third known technology) and JP-A-2000-2000
-73365 (fourth known technology) or
No. 181759 (fifth known technology) is known.

[0003] The first publicly known technique relates to a different concrete pile formed by connecting a large diameter upper concrete pile and a small diameter lower concrete pile to each other via a tapered joint member whose outer diameter gradually decreases toward the bottom. It is.

The second known technique relates to a driving method of a steel pipe pile having a different diameter, and uses a joint and driving fitting in which a small-diameter lower cylinder pipe is connected to a lower end of a large-diameter upper cylinder, and the small-diameter lower cylinder is used. A method in which a pipe is inserted into the upper end hollow portion of a small-diameter lower pile, and a large-diameter upper pile is inserted into the large-diameter upper cylindrical pipe, and in this state, the steel pipe piles at the upper and lower parts are connected to each other in the ground while driving. Technology.

According to the third known technique, a head of a small-diameter lower steel pipe pile is inserted into a lower end portion of a large-diameter upper steel pipe pile, and these are connected to each other through several connecting pieces to form a large-diameter upper steel pipe pile. The present invention relates to a technique relating to a device in which a mud-stirring excavator in which a small-diameter screw auger is connected to a lower end of a screw auger is inserted into the upper and lower steel pipe piles to perform excavation work.

The fourth known technique relates to a screw-in type steel pipe pile and a method for constructing the same. A small-diameter lower steel pipe is fitted into a lower end of a large-diameter upper steel pipe, and the steel pipe pile is connected by welding the two. The present invention also relates to a construction method in which an auger for agitating and excavating is inserted into a different-diameter pile having the above-described structure, and the auger is rotated and constructed.

[0007] The fifth known technique is a structure of a deformed steel pipe pile in which a small diameter lower steel pipe is connected to a lower end of a large diameter upper steel pipe by welding via a steel plate ring-shaped member. In particular, the upper and lower steel pipes are integrally connected coaxially, the upper steel pipe and the ring-shaped member are welded and fixed on the outer peripheral surfaces of both, and the lower steel pipe and the ring-shaped member are connected to the lower surface (the back surface) of the ring-shaped member. )
And the upper edge of the lower steel pipe are fixed to each other by welding.

[0008]

However, the first prior art requires a tapered joint member having a very special shape, which raises costs and is not economical. . Since the second known technique uses a joint and driving fitting composed of a large-diameter upper cylindrical pipe and a small-diameter lower cylindrical pipe,
Although effective when driving piles underground, it was difficult to reliably connect the upper and lower piles to form an expanded prefabricated pile.

In the third known technique, a head of a small diameter lower steel pipe pile is inserted into a lower end of a large diameter upper steel pipe pile and these are connected to each other by several connecting pieces. However, there were problems such as that the joining of the piles was unstable and that welding work at the time of joining was difficult.

The fourth known technique is a method in which a small-diameter lower steel pipe is fitted into the lower end of a large-diameter upper steel pipe and the two are welded to each other. There was a problem that joining was unstable and welding work at the time of joining was difficult. In addition, although an example of using a ring-shaped connecting member at the time of joining is also illustrated as a part of the fourth known technique, in this case, the welding surface is small and unstable, and an upward welding operation is required. Therefore, there has been a problem that connecting work on site is extremely difficult.

Further, the fifth known technique has a structure in which a large-diameter upper steel pipe and a small-diameter lower steel pipe are connected by a ring-shaped member as described above. This technique is a part of the fourth known technique. This is a technique already described, and has a problem that it is extremely difficult to connect on site because the welding surface is small and unstable, and an upward welding operation is required.

The prefabricated prefabricated pile according to the present invention is a completely new technology developed in view of the above-mentioned many problems. In particular, a joint steel material having a predetermined plate thickness is formed by combining a lower end of a large-diameter upper pile body and a small-diameter lower part. Provided is a technique for constructing an expanded prefabricated pile by firmly connecting the upper and lower pile bodies to each other by interposing the upper and lower pile bodies between the upper end of the pile body and welding these upper and lower pile bodies to a joint steel material. Things.

[0013]

In the prior art described above, when a large horizontal force or bending moment acts on the pile head from the upper structure, the vertical force acting on the pile and the horizontal force / bending moment are reduced. Depending on the combination, the number of piles has been increased or the diameter of the piles has been increased. On the other hand, in the present invention, the number of piles can be increased by forming the large-diameter upper pile body and the small-diameter lower pile body by welding each other via a joint steel material having a predetermined plate thickness. This technology enables economical design without increasing the pile diameter.

In particular, a construction method in which cement milk is injected into a bag attached to the tip of the pile to achieve high bearing capacity, or a method in which the ground at the tip of the pile is enlarged and excavated to provide a higher bearing capacity than the conventional construction method compared to the pile diameter It is effective for the construction method of expressing In the most effective case, the long-term vertical stress is 100 kg.
/ Cm ² or more is effective.

The prefabricated prefabricated pile according to the present invention is an invention which fundamentally improves each of the problems of the above-mentioned many known techniques, and the gist of the first invention is that the pile at the lower end of the large-diameter upper pile body is provided. In an enlarged prefabricated pile formed by connecting small diameter lower piles, the large diameter upper pile and the small diameter lower pile are welded to each other via a joint steel material having a predetermined plate thickness. This is an enlarged prefabricated pile with the following features.

In the first aspect of the present invention, the large-diameter upper pile and the small-diameter lower pile constituting the head pile are welded to each other via a joint steel material having a predetermined thickness. With this configuration, the overall configuration is extremely simple, and the upper and lower piles can be firmly connected in a stable state.

The gist of the second invention of the expanded ready-made pile of the present invention is as follows.
Plate thickness a of the portion of the joint steel material that comes into contact with the small diameter lower pile body
The dimensions of

(Equation 1)

A prefabricated head pile according to the first aspect of the present invention, which is a numerical value satisfying the following.

In the second aspect of the present invention, as described above, the thickness of the portion of the joint steel material abutting on the small-diameter lower pile body is set to a numerical value satisfying the above-described equation, and the joint steel material is manufactured. With this configuration, the upper and lower piles can be strongly and integrally connected using a joint steel material having desired strength and economical dimensions without waste.

The gist of the third invention of the expanded prefabricated pile of the present invention is as follows.
The expanded prefabricated pile according to the first invention or the second invention, wherein a downward taper is provided on a lower outer peripheral wall of the joint steel material.

In the third aspect of the present invention, as described above, since the lower outer peripheral wall of the joint steel is provided with a downward taper, unnecessary portions of the joint steel are eliminated, and the joint steel is made compact and compact. It can be made lightweight. In addition, by joining the large-diameter upper pile body and the small-diameter lower pile body using the joint steel material configured in this way, a prefabricated prefabricated pile that is smart, has good appearance, and can be smoothly driven into the ground is constructed. You can do it. Further, welding between the joint steel material and the small diameter lower pile body is facilitated.

The gist of the fourth invention of the prefabricated pile of the present invention is as follows.
By providing a ring-shaped notch along the joint between the joint steel material and the large-diameter upper pile or the joint between the joint steel and the small-diameter lower pile, and welding the ring-shaped notch by welding. An enlarged prefabricated pile according to any one of the first to third inventions, characterized in that a large diameter upper pile body or a small diameter lower pile body is connected to a joint steel material.

In the fourth aspect of the invention, as described above, the ring-shaped notch groove is provided along the joint between the joint steel material and the upper and lower piles joined thereto, so that the ring-shaped notch is provided. By welding the notch groove, the two can be firmly joined. In particular, by providing the ring-shaped notch groove along the joint, it is possible to increase the welding area of both, and to prevent the trace of welding from protruding largely outside the joint.

[0024]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing the appearance of an enlarged prefabricated pile according to the present invention; FIG. FIG. 3 is a cross-sectional explanatory view of a main part of the pre-expanded prefabricated pile, FIG. 3 is a cross-sectional explanatory view of a further enlarged main part of the pre-expanded prefabricated pile of FIG. 2, and FIG. .

In FIG. 1 to FIG. 3, reference numeral 1 denotes a head-expanded ready-made pile according to the present invention, which is a large-diameter upper pile 2 and a small-diameter lower pile 3, which are described later, and a joint steel member 4 for interconnecting them. It is composed of The large-diameter upper pile 2 is constituted by a concrete pile (SC pile) with an outer shell steel pipe.

The small-diameter lower pile 3 has a smaller diameter than the large-diameter upper pile 2, and is composed of SC piles. An end plate 5 is integrally fixed to an upper end edge of the small diameter lower pile body 3 by welding 6 in advance.

The joint steel member 4 is formed of a ring-shaped steel plate. The joint steel member 4 has a cutout recess 7 formed at the upper center edge thereof, and the lower outer peripheral wall of the joint steel member 4 has a downward taper 8. Are formed.

The notch recess 7 and the downward taper 8 are intended to be economical and light in weight by eliminating unnecessary portions of the joint steel material 4, respectively. Further, the downward taper 8 is configured so that the shape of the joint portion of the pre-expanded prefabricated pile 1 can be made smart thereon, and the pre-expanded prefabricated pile 1 can be smoothly driven into the ground. Further, welding of the joint steel material 4 and the small diameter lower pile 3 is facilitated by the downward taper 8.

Next, the above-mentioned joint steel material 4 used in the present invention can firmly connect the large-diameter upper pile body 2 and the small-diameter lower pile body 3 as will be described later, and the material is wasted. It is configured so that the weight of the entire vehicle can be reduced.

Accordingly, in order to achieve this object, the thickness of the joint steel material 4 at a predetermined location, that is, the thickness a of the portion contacting the outer peripheral surface of the small diameter lower pile 3 satisfies the following expression. It is configured to be a number.

[0031]

(Equation 1)

Using the above equations, the pile steel pipe thickness t, the large diameter upper pile body diameter D ₁ , the small diameter lower pile body diameter D, the yield stress degree σsy1 of the large diameter upper pile body steel pipe, the yield stress degree of the joint steel material σsy2
When the calculation was performed by inserting specific numerical values into the above, the following results were obtained.

[0033]

(Equation 2)

From the above calculations, the pile steel pipe thickness was set to 0.9 cm, the large diameter upper pile body diameter was set to 70 cm, the small diameter upper pile body diameter was set to 60 cm, the yield stress of the large diameter upper pile steel pipe, and the joint steel material. Is 2,400 kg / cm ² , the plate thickness a of the portion of the joint steel material 4 that is in contact with the outer peripheral surface of the small diameter lower pile 3 is 2.6 cm to 7.8 cm. It became clear that we needed to do that. In addition, as shown in FIG. 3 in particular, by providing a radius (curved portion) at the lower end 13 of the downward tapered portion, the dimension of the plate thickness α can be reduced.

In welding the large-diameter upper pile body 2 and the small-diameter lower pile body 3 to the joint steel member 4 having the above-described structure, respectively, as shown in FIG. A ring-shaped notch groove (groove groove) 9 having a V-shaped cross section is provided along the outer peripheral joint portion between the large-diameter upper pile body 2 and the small-diameter lower pile body 3. Are welded to each other so that they are firmly connected to each other.

In particular, by applying a downward taper 8 to the lower outer peripheral wall of the joint steel member 4, the lower edge of the joint steel member 4 and the outer peripheral surface of the small-diameter lower pile 3 can be substantially flush with each other. Both welding operations 10 can be performed sideways, facilitating the welding operation. In the above embodiment, the configuration in which the small-diameter lower pile body 3 is connected to the large-diameter upper pile body 2 has been described. However, the configuration in which the small-diameter central pile body (not shown) is connected to the large-diameter upper pile body 2. Can be configured in exactly the same way.

As described above, the joint steel 4 and the large-diameter upper pile 2
When the ring-shaped notch groove 9 is provided along the outer peripheral joint with the small diameter lower pile 3, the joint steel 4 and the large diameter upper pile 2
In addition, it is possible to increase the welding area of each of the small-diameter lower pile body 3 and the small-diameter lower pile body 3, thereby enabling a strong and reliable welding to both. Further, since the weld 10 is formed in the ring-shaped notch groove 9, it is possible to prevent the weld 10 from protruding largely outside the outer peripheral surface of the joint steel 4.

In the above-described embodiment, the joint steel member 4 having the notch recess 7 at the upper center edge has been described.
As shown in (a), it is also possible to configure the joint steel material 11 with a flat-plate ring-shaped steel plate in which the notch recess 7 is not provided. Further, as shown in FIG. 4 (b), the joint steel material is formed by joining two ring-shaped steel plates 12a and 12b having different diameters.
A stepped joint steel material 12 can also be used.

[0039]

According to the present invention, the large-diameter upper pile body and the small-diameter lower pile body are welded to each other via a joint steel material having a predetermined thickness, so that the construction is simple. Moreover, there is an effect that the upper and lower piles can be stably connected and mass-produced economically.

In the case where the plate thickness of the predetermined portion of the joint steel is determined by a predetermined mathematical formula, the upper and lower piles are integrally formed by using a joint steel having a desired strength and light weight and having no waste. Has the effect of being able to be configured by being connected to.

When a downward taper is provided on the lower outer peripheral wall of the joint steel, a compact and lightweight joint steel can be formed, and the welding work between the joint steel and the small diameter lower pile body can be facilitated. I can do it. Further, since no step is formed at the joint between the upper and lower piles, the expanded prefabricated pile can be driven into the ground. In particular, when a radius is provided at the lower end of the downward tapered portion, the thickness of the joint steel material can be reduced.

Further, when a ring-shaped notch groove is provided at the joint between the joint steel material and the upper and lower piles and the ring-shaped notch groove is welded, a large welding area can be obtained and the welding can be performed at the joint. It has the effect of being able to prevent large protrusions.

[Brief description of the drawings]

FIG. 1 is a side view showing the appearance of a head-expanded ready-made pile according to the present invention.

FIG. 2 is an explanatory sectional view of a main part of the prefabricated pile of FIG.

FIG. 3 is an explanatory sectional view showing a further enlarged main part of the prefabricated pile of FIG. 2;

FIGS. 4A and 4B are cross-sectional explanatory views of main parts of a head-expanded ready-made pile of another example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Expanded ready-made pile 2 Large diameter upper pile body 3 Small diameter lower pile body 4 Joint steel material 5 End plate 6 Welding 7 Notch recess 8 Downward taper 9 Ring notch groove 10 Welding 11 Joint steel material 12 Joint steel material 12a, 12b Ring steel plate 13 Taper lower end

Claims (4)

[Claims] An enlarged prefabricated pile constructed by connecting a small-diameter lower pile body to a lower end of a large-diameter upper pile body, wherein the large-diameter upper pile body and the small-diameter lower pile body have a predetermined thickness. An enlarged prefabricated pile, characterized by being mutually welded via a joint steel material having the same. 2. The dimension of the thickness a of the portion of the joint steel material that is in contact with the small diameter lower pile body is expressed by the following equation. The prefabricated expanded pile according to claim 1, wherein the value satisfies the following. 3. The expanded prefabricated pile according to claim 1, wherein a downward taper is provided on a lower outer peripheral wall of the joint steel material. 4. A ring-shaped notch groove is provided along a joint between the joint steel material and the large diameter upper pile body or a joint between the joint steel material and the small diameter lower pile body. 4. The prefabricated prefabricated pile according to claim 1, wherein a large diameter upper pile body or a small diameter lower pile body is joined to the joint steel by welding.