JPH0892956A - Square type post steel pipe pile with multi-stage spiral blade - Google Patents

Abstract

PURPOSE: To provide a steel pipe pile with a spiral blade having a large support force which can be easily constructed in a small construction site. CONSTITUTION: A plurality of large-sized spiral blades 5a to 5d are installed with a spacing to the outer peripheral part of a square post-shaped pile main body 1 provided with a base plate 2 and excavation blades 3 and 4 on the lower end while the outside diameter of the spiral blades is enlarged at a definite ratio as it rises upward. Prior to the execution of work, a rotary pushing device is mounted to a proper location between the upper and lower parts of the pile main body 1 and pushed in while it is being rotated. As a result, the spiral blade 4 cuts in the round while the excavated earth and sand at the tip of the pile is being pushed sideways and sinks downward by the rotary forward motion, thereby burying the pile without discharging the earth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a square column steel pipe pile with multi-stage blades, which has a large bearing capacity and can be economically constructed as a foundation pile for a structure constructed in an urban area.

[0002]

2. Description of the Related Art The construction of a basement has been approved as out-of-volume while the construction of a basement has been increased due to the effective use of the site due to the relaxation of building regulations in the city. The number of underground structures, such as rooms, has increased, and in buildings that are not supported by foundation piles, proximity excavation has increased, changes in the groundwater level, and problems such as ground loosening and ground subsidence due to the underground excavation earth retaining method have increased year by year. , A few years after the construction of a building, it is easily expected that a building will be adversely affected on a small site in the central area of the alluvial plain, and measures have to be taken in advance.

[0003] In addition, most large cities in Japan are concentrated in the alluvial plains developed around rivers, and the ground surface has many extremely soft layers that have not been particularly consolidated. Due to consolidation, there is an alluvium that is not a pile support layer but is a little stronger than the ground surface. The support layer that supports alluvial piles extends to more than 60 m deep and was built in the alluvial plain. Accidents that cause building problems due to subsidence and deformation due to unequal subsidence of the ground over the years, as the foundation of medium- and low-rise buildings in the city is economical, but long support piles are impossible Are particularly frequent in alluvial cities.

As a method for improving the soft ground on such a small site, a pile foundation such as deformed friction piles, soil cement improved piles and small diameter concrete piles, and a floating foundation method commonly referred to as a solid foundation are adopted. .

[0005]

However, these pile foundation methods are mainly used for constructions having a large road width and a large construction site, and construction machinery and equipment and pile materials are used for narrow roads and narrow sites. Since it cannot be carried in and there is no suitable construction method, construction with conventional technology is extremely difficult.

[0006] In addition, the ground surface of the ground on the narrow roads and narrow sites of the city developed in the alluvial plain is unconsolidated and contracts due to the change of the water level and the building load on the upper part with the passage of time. In such a soft ground of a big city, it is difficult to relocate from the familiar surrounding environment to other areas, and the height of the building is limited due to the increase of families, the need for a spacious living space, and the demand for effective use of the site. Along with the abolition, a 3-4 story building,
Although the construction of the basement has been approved as out-of-volume, the demand for construction of underground structures such as basements or underground heat storage rooms is increasing, but a construction method that can easily be carried in and constructed on narrow roads and small sites. The reality is that the development of a foundation pile method that does not generate residual soil is awaited.

The present invention improves the drawbacks of the conventional construction method, and in particular, it has a multi-stage spiral blade that exhibits a reliable support force without vibration, noise, and soil removal as a foundation pile on a small site of alluvial ground in a city. It is intended to provide a steel square pillar foundation pile.

[0008]

The structure of the present invention for achieving the above object will be described with reference to the drawings corresponding to the embodiments. The steel pipe pile of claim 1 is formed of a square steel pipe. The bottom plate 2 and the excavating blades 3 and 4 are provided at the lower end of the pile main body 1, and the outer peripheral surface of the pile main body 1 is spaced at substantially equal intervals in the length direction thereof and is at least twice the length of one side of the pile main body. Spiral wing 5a for screwing piles, which has a diameter of
5d is provided in a protruding manner, and the outer diameters of the spiral blades 5a to 5d are made large at a constant ratio as they go upward.

A steel pipe pile according to a second aspect of the present invention is the steel pipe pile according to the first aspect, wherein the lower end of the pile main body 1 is opened, and the excavating blades 4, 4 protruding laterally and downwardly of the pile main body 1 are provided at the lower end. It is characterized by being provided.

A steel pipe pile according to a third aspect of the present invention is the steel pipe pile according to the second aspect, characterized in that an inner spiral blade 8 extending substantially one turn is provided in the lower end portion of the pile body 1.

[0011]

In burying the steel pipe pile of the present invention, a rotary pushing device (not shown) is attached to the upper portion of the pile main body 1, and the pile main body 1 is rotated by being driven so as to be pressed against the ground. As a result, the excavating blades 3 and 4 at the lower end excavate and soften the soil at the tip of the pile, and the screw-in spiral blades 5a to 5d protruding from the outer peripheral surface of the pile bite into the ground and rotate the soil composition as a reaction force. Propulsion is not carried out, the earth and sand are not discharged, and the steel pipe pile is screwed in to a predetermined depth and buried.

At this time, in the steel pipe pile according to the first aspect, the earth and sand excavated and softened at the tip of the pile is pushed out to the side of the pile to consolidate the surrounding ground. Further, in the steel pipe piles according to claims 2 and 3, part of the excavated earth and sand flows into the pile body 1. Particularly, in the steel pipe pile of claim 3, due to the presence of the internal spiral blades, the sand and sand that have entered the pile main body 1 are transported, and at the end of the construction, the internal spiral blades 8a and 8b and the sand and sand make the lower part of the pile main body 1 Will be blocked.

[0013]

Embodiments of the steel pipe pile of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a bottom view of the same, and FIG. 3 is a side sectional view of the same part.

In the figure, reference numeral 1 denotes a pile main body, which is formed of a rectangular steel pipe having a quadrangular cross section to a required length. A bottom plate 2 is provided at the lower end of the pile body 1 by welding, and the bottom plate 2 is projected on the side surface of the lower end portion of the pile body 1 and on the side surface of the pile body 1 protruding downward. The inclined excavating blades 4 and 4 are provided by welding.

Further, a plurality of spiral blades 5a to 5d are formed on the outer periphery of the pile main body 1 from the lower end thereof to the upper side at substantially equal intervals and continuously formed over almost one turn. The outer diameter of each of the spiral blades 5a to 5d is twice or more the length D of one side of the pile body 1. Moreover, the pitch P of each spiral blade 5a-5d is the same. Further, the spiral blades 5a to 5d are successively increased in diameter at a constant ratio according to the lowermost spiral blade 5a to the upper spiral blades 5b to 5d, and connect the outer ends of the spiral blades 5a to 5d. The line a has an inverted conical shape. In addition, the interval between the spiral blades 5a to 5d is preferably set to a length that is a multiple of the pitch P of the spiral blades.

In the illustrated embodiment, one pile body 1 is provided with four spiral blades 5a to 5d, but the number of spiral blades can be appropriately increased or decreased. When the burying depth of a steel pipe pile becomes long, another pile is connected to this steel pipe pile before use.

When constructing the above-mentioned steel pipe pile, a rotary pushing device (not shown) is attached at an upper end portion of the pile body 1 or at an appropriate position between the upper and lower sides, and the pile body 1 is rotated while being pushed by the drive to drive the ground pile. Buried inside. In this case, since the pile main body 1 has a rectangular cross section, the rotational force can be easily transmitted even in the middle portion of the pile main body 1.

If the pile main body 1 is pushed in while being rotated, the tip ground of the pile is excavated by the action of the excavating blades 3 and 4 at the lower end.
It is softened and fluidized, making it easy for the piles to sink. And
First, the spiral blade 5a protruding from the bottom of the pile main body 1 bites into the ground and is rotationally propelled by using the ground bearing strength of the ground as a reaction force. At that time, the excavated and softened earth and sand is pushed out to the side surface of the pile and is consolidated. As a result, the pile will be twisted into the ground without soil. In this case, the propelling length per one rotation of the pile is substantially equal to the length of the pitch P of the spiral blade 5a.

As the steel pipe pile is propelled and settled down, the spiral blades 5b to 5d provided above also bite into the ground one after another and are similarly rotated and propelled. In this case, as shown in FIG. 9, since the spiral blades 5b to 5d are on the spiral locus b which is continuous with the spiral blade 5a at the lower end, the bite into the ground is good and the spiral blades 5b to 5d are easily performed. .

Therefore, in the steel pipe pile of the present invention, since the pile is settled by the rotational propelling of the spiral blades 5a to 5d, the pile is buried without waste and the ground around the pile is compacted. Become. In the buried steel pipe pile, since the spiral blades 5a to 5d that are spaced apart are gradually increasing in diameter as they become the upper ones, a conical spiral blade that spreads upwards is formed as a whole. The spiral wing 5a
Not only the vertical bearing force due to ~ 5d but also the wedge effect due to the conical shape works, and the bearing force in the diagonal direction is also added, so that a large supporting force can be obtained.

As described above, according to the present invention, when the burying depth of the steel pipe pile becomes long, other piles, for example, a steel pipe upper pile 6 without a blade, which is commonly used, are used for this steel pipe pile. To continue burying. In order to further enhance the effect, the steel pipe pile of the present invention can avoid the end-consolidated ground in which each of its conical wings is close to the surface of the ground, and bury it in a stable deep stratum having a strength of a certain value or more. desirable. By doing so, due to the large spiral wings 5a to 5d,
In addition to the pressure bearing effect of the blades, the conical wedge effect of each of the spiral blades 5a to 5d acts on the formation, and a greater frictional force and composite effect due to the wedge effect and supporting force can be obtained. Further, in the steel pipe pile of the present invention, since the pile main body 1 has a square shape, if it is buried according to the position of the prism of the building, it can be easily connected to the prism.

FIG. 4 shows another embodiment of the present invention in which the bottom plate 2 in the previous embodiment is excluded and the pile body 1 is
The lower end of is open 7. In the case of this embodiment, when the tip of the pile hits the hard ground, the excavated earth and sand enter the pile main body 1 through the opening 6, so that the penetration resistance is small and the solid ground is sure and easy. Can be submerged in

FIGS. 5 and 6 show still another embodiment of the present invention, in which the inner spiral blade 8 projects almost one turn on the inner peripheral surface of the lower end portion of the pile body 1 which is opened. It is set up. In the case of this embodiment, a part of the excavated earth and sand flows into the pile body 1 and is sent upward by the internal spiral blade 8. Therefore, it is possible to easily perform construction on hard ground that does not require consolidation of the ground on the side of the pile.

7 and 8 are different in the structure of the internal spiral blade 8. That is, the above spiral wing 8
Similarly to the above, two inner spiral blades 8a and 8b are provided so as to project almost one turn on the inner peripheral surface of the lower end portion of the pile body 1. The spiral blades 8a, 8b are arranged so that their lower end positions are different from each other by about half a turn so as to face the peripheral surface, and are protruded so as to intersect in an X shape when viewed from the side. In this case, since the lower ends of the both internal spiral blades 8a and 8b bite into the earth and sand that have flowed into the pile main body 1 at the same time on the circumferential surface, the effect of conveying the earth and sand that has flowed in is improved, and The effect of blocking the tip of the pile is also greater.

[0025]

As described above, the steel pipe pile according to the present invention is provided on the outer periphery of the steel pipe pile main body with the drilling blade provided at the lower end at substantially equal intervals in the length direction of the pile main body. A configuration in which screw-threaded spiral blades having a diameter of at least twice the diameter are provided in a projecting manner, and the outer diameters of the spiral blades separated from each other are increased at a constant ratio as they go upward. As a result, the pile is twisted into the ground by the rotary pushing drive, and it is easy to bury and can be constructed efficiently and inexpensively, and the bearing pressure of each spiral blade and the wedge effect in the ground due to the conical shape of each spiral is very effective. In addition, since the structure is simple, it can be manufactured at low cost.

Moreover, the burial can be carried out by simply rotating and pressing the steel pipe pile directly into the ground, and can be carried out to a deep depth without noise, vibration, and soil removal, especially on soft ground. It is excellent as a foundation pile for houses, etc.

Since the pile body has a prismatic shape,
Rotational force can be easily transmitted even in the middle position of the pile body, so it is possible to perform construction using a construction machine with a low pile tower, and it is also easy to construct piles in narrow premises or buildings. You can

Particularly, in the steel pipe pile according to claim 1, since the excavated earth and sand at the tip of the pile is pushed out to the side surface of the pile to consolidate the surrounding ground, it is suitable for the construction on the soft ground and the improvement of the soft ground. It also helps. Further, in the steel pipe pile according to the second aspect, since a part of the excavated earth and sand flows into the pile body, the construction on the hard ground can be surely and easily performed. Further, in the steel pipe pile according to claim 3, since the internal spiral blade is provided, a part of the excavated sediment can be transported into the pile body, and the soil and sand that have entered the pile body and the internal spiral blade are combined. As a result, the effect of blocking the tip of the pile is exerted, and a decrease in supporting force due to the opening of the lower end of the pile can be suppressed.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a bottom view of the same.

FIG. 3 is a vertical sectional view of the lower portion.

FIG. 4 is a vertical cross-sectional view of a lower portion showing another embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of a lower portion showing still another embodiment of the present invention.

FIG. 6 is a bottom view of the same.

FIG. 7 is a vertical cross-sectional view showing another example.

FIG. 8 is a bottom view of the same.

FIG. 9 is an explanatory view of a buried state of the steel pipe pile of the present invention.

[Explanation of symbols]

 1 Pile main body 2 Bottom plate 3,4 Excavation blade 5a-5d Spiral blade 6 Upper pile 7 Open part 8,8a, 8b Internal spiral blade

Claims (3)

[Claims] 1. A bottom plate and a drilling blade are provided at a lower end of a pile body formed of a rectangular steel pipe, and a length of one side of the pile body is provided on the outer peripheral surface of the pile body at substantially equal intervals in the length direction. The spiral blades for screwing piles, which have a diameter of more than twice the diameter, for almost one turn are projected, and the outer diameters of these spiral blades are made larger at a constant ratio as they go upward. A square column steel pipe pile with multi-stage spiral blades. 2. The prismatic column with multi-stage spiral blades according to claim 1, wherein a lower end of the pile main body is opened, and a drilling blade protruding laterally and downward of the pile main body is provided at the lower end. Steel pipe pile. 3. The square column steel pipe pile with multi-stage spiral blades according to claim 2, wherein an internal spiral blade extending over almost one turn is provided in the lower end portion of the pile body.