JP6810231B2 - Ready-made pile - Google Patents

Description

The present invention relates to a prefabricated pile, and more particularly to a prefabricated pile capable of ensuring a length as designed at a construction site.

When constructing a structure, it is necessary to construct a foundation structure to support the weight of the structure, and especially for large-scale structures, pile foundations that reach the support layer in the ground have come to be constructed. ing. There are various forms of such pile foundations, but they can be roughly classified into cast-in-place piles and ready-made piles. In recent urban development, noise regulation and vibration regulation are enforced because existing structures such as office buildings and condominiums exist in the surrounding area. Therefore, in areas where noise regulation and vibration regulation are enforced, the pre-boring method using ready-made piles is often adopted as a method for constructing pile foundations with low noise and low vibration.

The pre-boring method using ready-made piles is, for example, a method of excavating the ground to be constructed using an earth auger and injecting a rooting liquid or a pile fixing liquid into the excavation hole to lay the ready-made piles. In addition, the ground structure is grasped by conducting survey boring at the construction site, and the design is such that the tip of the existing pile, which is the foundation structure, reaches the support layer.

Conventionally, various techniques have been proposed for surely reaching the tip of the pile to the support layer (see, for example, Patent Document 1 and Patent Document 2). In the technique described in Patent Document 1, a steel pipe pile is composed of a pile body and an insert pile, and the pile body is rotated by a pile driver to excavate the ground with spiral blades and penetrate the pile body into the ground. It is designed to let you. In this method, if the spiral blade hits a hard intermediate layer shallower than the target support layer and the pile body cannot be penetrated, an insert pile is inserted into the pile body and the tip has a sharp shape. By abutting the part against the intermediate layer and hitting the upper end of the insert pile, the ground is dug with the spiral blade and the hard intermediate layer is destroyed. After that, the pile body is rotated to excavate the intermediate layer so that the tip of the pile body reaches the support layer, which is the final destination.

The technique described in Patent Document 2 relates to a connection structure for connecting a steel pile to an upper part of a concrete pile. This technique fixes the fitting to the top of the concrete pile and the base plate to the bottom of the steel pile. Further, a screw hole is formed in the connector, and a hole is formed in the base plate at a position facing the screw hole. Then, the steel pile is connected to the upper part of the concrete pile via a connecting bolt that is screwed into the screw hole and the hole portion.

Japanese Unexamined Patent Publication No. 2012-162947 JP-A-2009-299412

By the way, the ready-made piles are manufactured at a factory so as to reach the support layer by grasping the depth of the support layer by survey boring or the like before construction, and are carried to the construction site. However, the ground to be constructed is not always uniform, and even if the depth of the support layer is actually measured by survey boring or the like, an error may occur in the depth prediction of the support layer. In particular, when the actual support layer is lower than the predicted depth, the tip of the prefabricated pile prepared based on the prediction may not reach the support layer.

In this case, it is necessary to reorder the ready-made piles that match the depth of the support layer, which not only delays the construction period but also increases the construction cost. In order to construct a structure that matches the structural design, it is natural that the soundness of the foundation structure is required, and there is room for further ingenuity in the management of existing piles. If the length of the prepared prefabricated pile does not match the depth of the support layer, a steel pile or the like may be added to the upper part of the prefabricated pile or a footing may be formed to reach the lower end of the pile to the support layer. It is also possible to make it.

However, at the lower end of the pile, it is only necessary to consider the axial force (tip bearing force) for supporting the load of the structure, but at the upper part of the pile, the bending moment due to the shaking of the structure due to seismic motion etc. is considered. Must. Therefore, when adding steel piles or the like to the upper part of the existing piles prepared based on the structural calculation already performed, it is necessary to perform the structural calculation again to ensure the soundness of the structure. It is also conceivable to make the lower end of the prefabricated pile, which is insufficient in length, reach the support layer and provide footing to connect the prefabricated pile and the structure, but the superstructure is provided by the amount of the newly provided footing. The weight of the structure increases, and structural calculations must be performed again to ensure the soundness of the structure. Therefore, when the lower end of the pile does not reach the support layer, it is preferable to add a member for adjusting the length to the lower end of the pile.

The present invention has been proposed in view of the above circumstances, and can be constructed in accordance with the depth of the support layer in the ground to be constructed, and can be easily rotationally penetrated into the lowermost end portion and exhibits tip bearing capacity. It is an object of the present invention to provide a prefabricated pile that can surely reach the support layer according to the current state of the ground to be constructed, for the prefabricated pile having a mechanism for the construction.

The ready-made pile of the present invention has the following features in order to achieve the above-mentioned object. That is, the prefabricated pile of the present invention can be constructed in correspondence with the depth of the support layer in the ground to be constructed, and has a mechanism for easily rotating and penetrating the lowermost end portion and expressing the tip bearing capacity. From multiple types of prefabricated piles, each with a different length to adjust the length of the prefabricated pile, and the pile body, which has a length determined by design to correspond to the predicted depth of the support layer. Therefore, it is characterized by having an auxiliary pile that can be connected to the lower end of the pile main body and a connecting portion provided between the pile main body and the auxiliary pile.

Then, the mechanism and the pile body can be separated at the portion where only the axial force acts on the pile body, and when the support layer is lower than the predicted depth, the auxiliary pile having a plurality of types of lengths. Select an auxiliary pile with a length that allows the lower end to reach the support layer by connecting to the pile body from the inside, and with the mechanism and the pile body separated, select the auxiliary pile for the lower end of the pile body. It is designed to be connected in one piece.

Further, the prefabricated pile and the mechanism can be separated from the tip of the prefabricated pile in a region of 3 to 5 times the pile diameter D. Further, the auxiliary pile has connecting portions at both ends, and a plurality of auxiliary piles can be continuously connected in the length direction.

The prefabricated pile of the present invention can be constructed in accordance with the depth of the support layer in the ground to be constructed, and has a mechanism for easily rotating and penetrating the lowermost end and expressing the tip bearing capacity. Even if the pile is a pile and the support layer is below the predicted depth, an auxiliary pile can be connected to the lower end of the pile body to form a ready-made pile with the designed length. It is possible to ensure that the lower end of the existing pile reaches the support layer according to the current state of the ground to be constructed.

In addition, the mechanism and the pile body are separated at the part where only the axial force acts on the pile body, and the selected auxiliary pile is integrally connected to the lower end of the pile body so that only the axial force is taken into consideration. Since the structure is such that the auxiliary pile is connected to the lower end of the ready-made pile, it is not necessary to perform structural calculation again, and the soundness of the structure can be ensured by the basic structure as designed.

An exploded perspective view of a ready-made pile according to an embodiment of the present invention. The side view of the state which connected the pile main body and the auxiliary pile which concerns on embodiment of this invention. Explanatory drawing which shows the construction example of the prefabricated pile by the pre-boring method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 show the prefabricated pile according to the embodiment of the present invention, FIG. 1 is an exploded perspective view of the prefabricated pile, FIG. 2 is a side view of a pile main body and an auxiliary pile connected, and FIG. Is an explanatory diagram of a construction example of a ready-made pile by the pre-boring method.

<Applicable object of the present invention>
The prefabricated pile according to the present invention is a technique that can be applied to all prefabricated piles without depending on the mechanism for expressing the tip bearing capacity and the construction method. That is, in the following description, the prefabricated piles constructed by the pre-boring method will be described as an example, but the prefabricated piles according to the present invention are not limited to the prefabricated piles constructed by the pre-boring method, but the prefabricated piles constructed by other construction methods. It is a technology that can also be applied to.

<Pre-boring method>
The prefabricated pile according to the present invention is a technique suitable for a pre-boring method in which, for example, an excavation hole reaching to the supporting ground is formed and a prefabricated pile made of concrete or the like is sunk in the excavation hole. In the pre-boring method using this prefabricated pile, as shown in FIG. 3, a hole is drilled in the ground to be constructed using an earth auger 20 or the like until it reaches the support layer (a, b). Then, the earth auger 20 is pulled up, and the filler 40 made of the root hardening liquid or the pile fixing liquid is injected into the excavation hole 30 (c). After that, the prefabricated pile 10 is sunk in the excavation hole 30, the tip of the prefabricated pile 10 is fixed to the support layer with a root hardening liquid, and the gap between the peripheral surface of the prefabricated pile 10 and the inner wall of the excavation hole 30 is filled. Fill with material 40 (d). Although not shown, a diameter-expanded portion having a larger diameter than the upper portion may be formed at the lower end portion of the excavation hole 30.

<Prepared pile>
The ready-made pile 10 according to the embodiment of the present invention can be constructed according to the depth of the support layer in the ground to be constructed, and as shown in FIGS. 1 and 2, the pile body 11 and the pile body 11 An auxiliary pile 12 that can be connected to the lower end portion of the pile body 12 and a connecting portion 13 that connects the pile main body 11 and the auxiliary pile 12 are provided.

<Pile body>
The pile body 11 has a length determined by design. That is, in order to construct the ready-made pile 10, the depth of the support layer is predicted by conducting a survey boring or the like in advance, and the ready-made pile 10 having a length reaching the support layer is manufactured at the factory and transported to the construction site. The ready-made pile 10 having the length determined by this design is the pile body 11. If the depth of the support layer is as expected, the carried-in pile body 11 is used as it is as the ready-made pile 10.

On the other hand, if the depth of the support layer is located lower than expected, the length of the ready-made pile 10 carried in is not sufficient, and the tip of the pile body 11 does not reach the support layer, FIGS. 1 and 2 show. As shown, the auxiliary pile 12 is connected to the lower end of the pile main body 11 and adjusted so that the lower end of the auxiliary pile 12 reaches the support layer.

<Auxiliary pile>
The auxiliary pile 12 is a member having the same outer diameter as the pile main body 11, and has a length for adjusting the length of the ready-made pile 10. As shown in FIG. 2, the lengths of the auxiliary piles 12 are, for example, about 30 cm, 50 cm, and 100 cm, and by combining the auxiliary piles 12 having these lengths, the ready-made pile 10 integrated with the pile main body 11 is formed. The lower end of the prefabricated pile 10 is made to reach the support layer.

<Connection>
The connecting portion 13 is a portion for connecting the pile main body 11 and the auxiliary pile 12, for example, as shown in FIG. 1, a quick provided between the lower end portion of the pile main body 11 and the upper end portion of the auxiliary pile 12. It consists of joints and the like. Further, it is preferable that the auxiliary stake 12 is also provided with a connecting portion 13 for connecting the auxiliary stakes 12 to each other. The shape of the connecting portion 13 is not limited to that shown in FIG. 1, and may have any structure as long as the pile main body 11 and the auxiliary pile 12 or the auxiliary pile 12 can be connected to each other. For example, a female. Any connection structure may be used, such as a threaded portion and a male threaded portion, a cotter joint, a slide cotter joint, a victic joint, a one-touch coupler joint, and welding via a metal fixture.

In addition, in the ready-made pile 10 provided with a mechanism for easily performing rotational penetration at the most advanced portion (lowermost end portion) such as a wing pile or a mechanism for expressing the tip bearing capacity, these mechanisms are used. Instead of connecting the auxiliary pile 12 to the lower part, the auxiliary pile 12 may be connected to a portion above these mechanisms where only the axial force acts. That is, in the blade pile, the blade-shaped portion and the pile main body 11 are separable, and the auxiliary pile 12 is connected to the upper portion of the blade-shaped portion where only the axial force acts. In this case, for example, the auxiliary pile 12 may be connected from the tip of the ready-made pile 10 to a region about 3 to 5 times the pile diameter D.

<Adjusting the length of ready-made piles>
The prefabricated pile 10 of the present embodiment has the above-described configuration, and when the depth of the support layer is located lower than expected and the prefabricated pile 10 carried in is not long enough, one is placed at the lower end of the pile body 11. By connecting one or a plurality of auxiliary piles 12, the lower end portion of the ready-made pile 10 in which the pile main body 11 and the auxiliary piles 12 are integrated reaches the support layer. At this time, auxiliary piles 12 having an appropriate length are used alone or in combination according to the insufficient length of the pile main body 11.

<Other embodiments>
In the embodiment shown in FIG. 1, the description is made assuming a cylindrical concrete pile, but the ready-made pile 10 of the present invention is not limited to the one shown in FIG. 1, and an auxiliary pile is provided at the lower end of the pile body 11. Pile of any material and shape may be used as long as 12 can be connected.

10 Ready-made pile 11 Pile body 12 Auxiliary pile 13 Connection part 20 Earth auger 30 Drilling hole 40 Filler

Claims (3)

It is a ready-made pile that can be constructed according to the depth of the support layer in the ground to be constructed, has a mechanism for easily rotating and penetrating into the lowermost end, and has a mechanism for developing tip bearing capacity.
A pile body with a length designed to correspond to the predicted depth of the support layer,
In order to adjust the length of the ready-made pile, there are multiple types of piles with different lengths, and an auxiliary pile that can be connected to the lower end of the pile body.
A connecting portion provided between the pile body and the auxiliary pile,
With
The mechanism and the pile body can be separated at a portion where only axial force acts on the pile body.
When the support layer is lower than the predicted depth, select an auxiliary pile having a length that the lower end reaches the support layer by connecting to the pile body from the auxiliary piles having a plurality of types of lengths. Then, in a state where the mechanism and the pile main body are separated, the selected auxiliary pile is integrally connected to the lower end portion of the pile main body.
A prefabricated pile characterized by that. The prefabricated pile and the mechanism are separated from the tip of the prefabricated pile in a region of 3 to 5 times the pile diameter D.
The ready-made pile according to claim 1, characterized in that. The auxiliary pile has the connecting portions at both ends, and a plurality of the auxiliary piles can be continuously connected in the length direction.
The ready-made pile according to claim 1 or 2, characterized in that.

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