JP2007285019A - Foundation pile structure and sc pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foundation pile structure capable of soundly and smoothly transmitting a load, when connecting a steel pipe pile and an SC pile. <P>SOLUTION: This SC pile 2 having bending yield strength larger than the steel pipe pile 1, is joined as an upper pile to an upper part of the steel pipe pile 1 as a lower pile. One stage or a plurality of stages of projections 2c are arranged in an inner peripheral surface lower part of a steel pipe 2a constituting the SC pile 2. A vertical load transmitted by being shared by a concrete 2b part of the SC pile 2, is gradually transferred to the steel pipe 2a side via the projections 2c in the vicinity of a joining part of the steel pipe pile 1 and the SC pile 2 suddenly changing in a cross section, and is stably transmitted to the steel pipe pile 1 as the lower pile. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a foundation pile structure using a steel pipe pile and an SC pile (a steel-concrete composite pile made of steel pipe and concrete integrated on the inner surface side of the steel pipe), and an SC pile usable for the foundation pile structure. Is.

  With the recent increase in bearing capacity of foundation piles and the increase in design seismic force, steel pipe piles, which have been considered to have excellent bending performance in the past, can be applied to horizontal forces from buildings during earthquakes and in underground areas. In some cases, the proof strength is insufficient for a large load generated by ground displacement, and an expensive steel pipe pile having a considerably large thickness is required to obtain the required proof strength.

  In such a case, after placing the steel pipe pile, concrete is placed in the hollow portion of the steel pipe pile, and a method such as improving the bending strength by adopting a steel pipe-concrete structure has been adopted. This method has the following problems.

  (1) Since a hollow part is secured in the steel pipe and the inner peripheral surface of the steel pipe is required to be in a clean state without deposits, when earth and sand or cement milk is left in the steel pipe, The removal and cleaning of the surface of the steel pipe are required, which makes it difficult or difficult to implement. For this reason, there are large application restrictions depending on the construction method of the pile.

  (2) After the construction of piles is completed, the process of dropping to a predetermined depth, installing a lid, and placing concrete increases, so the field work and construction period increase.

  (3) There is a limit to the strength and quality that can be obtained due to the concrete placement on site and, in some cases, the need to cast concrete in water and mud.

  Therefore, in the present invention, among foundation piles mainly composed of steel pipe piles, SC piles having a greater bending strength than steel pipe piles are applied to required parts such as the ground surface where a large horizontal force acts during an earthquake. It was decided to propose a foundation pile structure in which steel pipe piles and SC piles were joined together.

  SC piles are prefabricated piles that are manufactured in advance by integrating high-strength concrete on the inner peripheral surface of the steel pipe at the factory. Therefore, it is not necessary to place concrete in a separate process after pile construction. The case problem is solved.

  In addition, SC piles are manufactured at the factory, so it is possible to apply concrete with much higher strength than on-site casting, as well as to obtain stable quality and to combine steel pipes with appropriate strength and thickness and concrete strength. By selecting, it is possible to produce a product having a required bending strength.

  Conventionally, a structure in which different kinds of pre-made piles, that is, pre-made concrete piles (PC piles, PHC piles), steel-concrete composite piles (SC piles), steel pipe piles, or the like are connected together is known.

  However, as described in, for example, Patent Document 1 and Patent Document 2, these steel pipe piles are connected to a required portion of a foundation pile mainly made of ready-made concrete piles, that is, near the ground surface where a large horizontal force acts during an earthquake. Instead of ready-made concrete piles, steel pipe piles with higher bending strength are to be applied to such parts.

  In addition, for the same reason, a structure in which SC piles of the same diameter are connected to the upper piles of ready-made concrete piles has also been put into practical use. It was not intended to apply piles.

  On the other hand, there is also a problem in joining when connecting ready-made piles, and in the case of ready-made concrete piles, butt welding is often performed on the site using end plates, so far the quality and strength aspects The issues in have been pointed out. Furthermore, when steel pipe piles and SC piles are joined together, the vertical contact acting on the pile foundation does not result in surface contact at the end plates as in the case of joining pre-made concrete piles, but the cross section changes rapidly at the joint. Consideration is necessary from the viewpoint of smooth and sound transmission of load and horizontal load.

  As a means for solving such a problem in joining different kinds of ready-made piles, a method disclosed in Patent Document 3 is disclosed. This provides a means for joining SC piles and other ready-made piles, and by projecting the end of the steel pipe of SC pile as it is from the end of the concrete as it is, the inside of the protruding part of the steel pipe In this method, a recess is formed in the recess, and the end of the other pile is inserted into the recess.

  However, this method has the following problems from the viewpoint of joining the steel pipe pile and the SC pile.

  (1) The vertical load must be transmitted by the contact between the steel pipe pile end face and the SC pile end plate, and it is difficult to transmit the indentation load from the structure smoothly and soundly. In order to transmit the indentation load stably, at least the end surface accuracy of both ends and vertical accuracy at the time of pile connection are required to avoid point contact between the steel tube end surface and the end plate. It is necessary to take measures such as rib reinforcement. Furthermore, regarding the transmission of the load in the drawing direction, the steel pipe pile end face and the SC pile end plate can be separated from each other, so that the load becomes further unstable.

  (2) Since the steel pipe pile is inserted into the recessed part formed inside the protruding steel pipe of the SC pile, the inner diameter of the steel pipe of the SC pile and the outer diameter of the steel pipe pile to be joined to this need to be substantially equal. However, considering the dimensional accuracy of steel pipes, the accuracy of construction on site, and the environment, joining steel pipe piles and SC piles by this method is not easy.

Japanese Patent Publication No. 05-047685 JP 2003-232033 A Japanese Patent No. 3724933

  The present invention has been made in order to solve the problems of insufficient horizontal strength due to high bearing capacity of steel pipe piles and large scale of design earthquake motion, and is a steel pipe pile and an SC pile having a larger bending strength than that. The foundation pile structure which can transmit each load of pushing, pulling out, and bending (horizontal) in a healthy and smooth manner, and the SC pile usable for the foundation pile structure are provided.

  The foundation pile structure according to claim 1 of the present application is formed by joining an SC pile having a higher bending strength than the steel pipe pile as an upper pile or a part of the upper pile on the upper portion of the steel pipe pile. One or a plurality of projections are provided at the lower part of the inner peripheral surface of the steel pipe to be formed.

  The SC pile is used for the upper pile, and it is intended to apply a pile with a greater bending strength than the steel pipe pile to the vicinity of the ground surface where a large horizontal force acts during an earthquake. There is a problem of stress transmission due to sudden change in cross section.

  According to the present invention, by providing a protrusion on the lower part of the inner peripheral surface of the steel pipe constituting the SC pile, the load shared and transmitted by the concrete part of the SC pile is transferred to the lower part of the inner peripheral surface of the steel pipe of the SC pile. It moves to the steel pipe side gradually through the protrusion which is located, and a vertical load can be stably transmitted to the steel pipe pile as a lower pile.

  The foundation pile structure according to claim 2 of the present application is formed by joining an SC pile having a higher bending strength than the steel pipe pile as an upper pile or a part of the upper pile on the upper part of the steel pipe pile. The outer diameter is smaller than the outer diameter of the SC pile, larger than the diameter of the hollow portion of the SC pile, and the upper end of the steel pipe pile and the end plate provided at the concrete end of the SC pile are joined by welding. It is characterized by being.

  The basic idea is the same as that of the invention according to claim 1 and solves the problem of stress transmission due to a sudden change in the cross section at the joint when the SC pile is used as the upper pile, but the invention according to claim 2 Since the steel pipe pile is joined between the outer edge and the inner edge of the end plate of the SC pile, the bending transmitted from the end plate to the vicinity of the end of the steel pipe pile cancels out from both directions, and the steel pipe pile is perpendicular to the steel pipe pile. The load can be transmitted stably and a smooth vertical load can be transmitted.

  The foundation pile structure according to claim 3 of the present application is formed by joining an SC pile having a bending strength larger than that of the steel pipe pile as an upper pile or a part of the upper pile at the upper portion of the steel pipe pile. The inner surface side steel pipe is integrated with the inner surface side of the concrete, the lower part of the inner surface side steel pipe protrudes the required length from the end portion of the concrete, and the lower end portion of the inner surface side steel pipe is joined to the upper end portion of the steel pipe pile. It is characterized by.

  The foundation pile structure according to claim 3 is the same as that of claims 1 and 2 in that it solves the problem of stress transmission due to a sudden change in the cross section at the joint when SC pile is used for the upper pile. In the upper part, the load shared and transmitted by the steel pipe and concrete is gradually transmitted to the inner surface side steel pipe, and the vertical load can be stably transmitted to the steel pipe pile as the lower pile.

  In addition, the invention which concerns on the above Claims 1-3 exists in the relationship which can be used together in one foundation pile structure depending on embodiment.

  The SC pile according to claim 4 is an SC pile in which concrete is integrated with the inner peripheral surface of the steel pipe, and one or more continuous or discontinuous protrusions are provided on the inner peripheral surface of the end portion of the steel pipe. It is characterized by this.

  The SC pile according to claim 4 can be applied to the foundation pile structure according to claim 1 as it is.

  A fifth aspect of the present invention is the SC pile according to the fourth aspect, wherein the projection is formed by a weld bead.

  In the invention of the present application, when the projection provided on the inner peripheral surface of the steel pipe constituting the SC pile is applied to the foundation pile structure, the lower part, the SC pile as a product, may be formed at the end thereof, and Due to the relationship with the height of the protrusion (about 5 mm to 15 mm) necessary for stress transmission in the vicinity of the suddenly changing section, it is efficient to form with a weld bead and the manufacturing cost is also low.

  The SC pile according to claim 6 is a hollow SC pile in which concrete is integrated on the inner peripheral surface of the steel pipe, and an inner surface side steel pipe is integrated on the concrete inner surface side of the SC pile, At least one end protrudes from the end of the concrete for a required length.

  The SC pile according to claim 6 can be applied to the foundation pile structure according to claim 3 as it is.

  In the SC pile according to claim 6, when one or more continuous or discontinuous protrusions are provided on the inner peripheral surface of the end of the steel pipe and / or the outer peripheral surface of the inner steel pipe. Is limited.

  The protrusion increases the adhesion between the steel pipe and the concrete. In the present invention, such a protrusion is provided on the inner peripheral surface of the end of the steel pipe on the outer side of the SC pile, thereby joining to another pile such as a steel pipe pile. In this case, smooth stress transmission can be achieved at the sudden change section.

  On the other hand, as for the inner surface side steel pipe itself, it is intended to smoothly transmit stress at the section where the cross section is suddenly changed, and the position of the protrusion is not particularly limited.

  In the SC pile according to claim 6 or 7, the case where a part or all of the protrusion is formed by a weld bead is limited.

  The reason why the projection formed on the inner peripheral surface of the end of the steel pipe outside the SC pile is formed by the weld bead is the same reason as in the fifth aspect. In consideration of stress transmission with concrete and workability, the outer peripheral surface of the inner surface side steel pipe is also relatively efficient to be formed by a weld bead, and the manufacturing cost is also low.

  However, only one of them may be formed with a weld bead, and the other may be used in combination with other types of protrusions, for example, using a protrusion of a striped steel plate.

  According to the foundation pile structure according to claim 1 of the present application, a large horizontal force acts during an earthquake by joining an SC pile having a bending strength larger than that of the steel pipe pile as the upper pile to the upper part of the steel pipe pile as the lower pile. By providing a protrusion on the lower part of the inner peripheral surface of the steel pipe that constitutes the SC pile, the load that is shared and transmitted by the concrete part of the SC pile can be transferred to the inside of the steel pipe of the SC pile. It moves to the steel pipe side gradually through the protrusion located in the lower peripheral surface, and the vertical load can be stably transmitted to the steel pipe pile as the lower pile.

  According to the foundation pile structure according to claim 2 of the present application, a large horizontal force acts at the time of an earthquake by joining an SC pile having a bending strength larger than that of the steel pipe pile as the upper pile to the upper part of the steel pipe pile as the lower pile. Since the steel pipe pile is joined between the outer edge and the inner edge of the end plate of the SC pile, the bending transmitted from the end plate to the vicinity of the end of the steel pipe pile from both directions can be secured. It becomes a form that cancels out, and the vertical load is stably transmitted to the steel pipe pile, and smooth transmission of the vertical load can be realized.

  According to the foundation pile structure according to claim 3 of the present application, a large horizontal force acts during an earthquake by joining an SC pile having a bending strength larger than that of the steel pipe pile as the upper pile to the upper part of the steel pipe pile as the lower pile. The load that is shared and transmitted by the steel pipe and concrete at the upper part of the SC pile is gradually transmitted to the inner steel pipe, and the vertical load is stably transmitted to the steel pipe pile as the lower pile. Can do.

  The SC pile according to claims 4 to 8 can exert the above-described effects by being applied to the foundation pile structure according to claim 1, 2, or 3. In addition, if the protrusion for facilitating the stress transmission in the suddenly changing section is formed with a weld bead, it is efficient and the manufacturing cost is low.

  FIG. 1 shows one embodiment when the foundation pile structure according to claim 1 is configured using the SC pile according to claim 4 or 5, and in the upper part of the steel pipe pile 1 as a lower pile, The SC pile 2 as an upper pile is joined.

  A plurality of projections 2 c are provided at the lower part of the inner peripheral surface of the steel pipe 2 a constituting the SC pile 2, and end plates 2 d for joining are provided at both ends of the SC pile 2.

  In this foundation pile structure, the steel pipe pile 1 and the SC pile 2 can be joined together by welding at the site in the same manner as a longitudinal connection between ordinary pre-made piles. Alternatively, the steel pipe pile 1 and SC pile 2 having a predetermined length may be joined in advance by factory welding or the like, and then carried into the site, and the longitudinal joint on the site may be formed by joining common steel pipe piles.

  In the present invention, the SC pile 2 having a larger bending strength under the acting axial force than the bending strength of the steel pipe pile 1 to be joined is used. Since the strength of the SC pile 2 varies depending on the material and thickness of the steel pipe 2a used on the outer periphery of the SC pile 2, and the strength of the concrete 2b on the inner circumference side, these combinations are selected so that the required strength can be obtained. do it.

  For example, it is conceivable that the thickness of the steel pipe 2a constituting the SC pile 2 is equal to or greater than the thickness of the steel pipe pile 1 connected thereto. Moreover, when using SC pile 2 having a diameter larger than that of steel pipe pile 1, it is easy to configure SC pile 2 having a bending strength greater than that of steel pipe pile 1, and the combination of the material and thickness of steel pipe 2a and the strength of concrete 2b is also possible. Considering it, it is possible to significantly increase the bending strength compared to the steel pipe pile 1.

  2 (a) and 2 (b) show a joint portion of a lower pile and an upper pile in another embodiment of the invention according to claim 1 using the SC pile according to claim 4 or 5, and FIG. (c) shows a comparative example.

  The steel pipe pile 1 and the SC pile 2 are joined together by welding the end plate 2d of the SC pile 2 and the steel pipe pile 1 as shown in FIG. (Fig. 2 (c) as a comparative example), and the steel pipe 2a of the SC pile 2 is projected from the concrete 2b by a predetermined length as shown in Fig. 2 (a). In addition, a method of joining the steel pipe pile 1 by welding using this portion can be employed.

  Moreover, when making the steel pipe 2a of SC pile 2 project, the mechanical coupling 4 can also be used for joining with the steel pipe pile 1 like FIG.2 (b).

  In the case of the method of joining the steel pipe 2a of the SC pile 2 and the steel pipe pile 1, the end plate at the bottom of the SC pile 2 can be omitted, or rationalization such as making the minimum simple end plate necessary for manufacturing. Is also possible.

  On the other hand, in the case of the method of joining with the steel pipe pile 1 using the end plate 2a of the SC pile 2 as shown in FIG. 1, the joining with the steel pipe pile 1 is easy, and the load transmission to the steel pipe pile 1 is possible. It is also possible to use a dedicated plate that is devised in shape so as to be more stable.

  In the present invention, the optimum structure is selected in consideration of various conditions such as the proof stress necessary for the SC pile 2, the construction method of the pile, the joining method of the SC pile 2 and the steel pipe pile 1, and the restrictions on the manufacture and transportation of the SC pile 2. can do.

  3 (a) and 3 (b) are explanatory views of the load transmission mechanism in the invention according to claim 1, and FIG. 3 (c) is an explanatory view of the load transmission mechanism in the comparative example.

  As shown in Fig. 1 and Fig. 2 (a) and (b), the SC pile 2 using a steel pipe having a predetermined number of protrusions 2c on the inner peripheral surface is used, and this is connected to the steel pipe pile 1. As a result, the vertical load can be smoothly transmitted as shown in FIGS.

  That is, among the loads transferred and shared by the steel pipe 2a and the concrete 2b at the upper part of the SC pile 2, the load shared by the concrete 2b gradually moves to the steel pipe 2a of the SC pile 2 through the protrusion 2c, and the steel pipe pile In the joint portion with 1, the shared load of the concrete 2 b becomes a very small state close to zero, so that the vertical load can be stably transmitted to the steel pipe pile 1.

  Note that the end plate 2d at the lower end of the SC pile 2 is not necessarily required from a structural point of view if a sufficient number of protrusions for transferring the shared load of the concrete 2b to the steel pipe 2a of the SC pile 2 is secured. 2 (a) and 2 (b) and the corresponding configuration shown in FIG. 3 (b) may be configured without the end plate 2d. Alternatively, even if the end plate 2d cannot be omitted due to manufacturing reasons or the like, the shape and material can be rationalized by using a minimum required simple end plate.

  FIG. 2 (c) shows a case where the protrusion 2 c is provided on the entire inner peripheral surface of the steel pipe 2 a constituting the SC pile 2 as a comparative example. In this case, it is conceivable to use a striped steel plate or the like as the material of the steel pipe 2a. However, the steel pipe 2a of the SC pile 2 is gradually subjected to the shared load of the concrete 2b with respect to the sudden change in the cross section at the joint between the SC pile 2 and the steel pipe pile 1. It is not effective in terms of migrating to and is wasteful.

  The SC pile 2 as shown in FIGS. 2 and 3 can be manufactured by placing and curing the concrete 2b using the steel pipe 2a provided with the protrusion 2c in advance, and the protrusion 2c on the inner peripheral surface of the steel pipe 2a is at least What is necessary is just to install the number of steps required in order to transmit a load between the concrete 2b of the SC pile 2, and the steel pipe 2a in one edge part. In this case, the protrusions 2c may be continuous or discontinuous, and the protrusions 2c do not have to be strictly separated for each step, and may be in a moderately dispersed state.

  In addition, as shown in Fig. 2 (a) and (b), the steel pipe is extended and protruded from the concrete part of the SC pile, and as described above, this projecting part is used as the lower pile. It can also be set as the structure joined to the steel pipe pile 1. FIG.

  2 (a) and 2 (b) show the case where there is no lower end plate 2d, but even if there is a lower end plate 2d, the end plate 2d is similar to FIG. 2 (c) as a comparative example. If the outer peripheral portion of the steel tube 2a is in contact with the inner peripheral surface of the steel pipe 2a, the steel pipe 2a can be similarly protruded from the concrete 2b by a predetermined length.

  The steel pipe pile 1 and the SC pile 2 are joined in such a manner that the pipe piles 1 are sequentially cast in the field as described above, and the steel pipe pile 1 having a predetermined length is joined to the lower portion of the SC pile 2 in advance at the factory. A method of bringing the steel pipes into the field as a single piece, and welding the steel pipes together in the same manner as a normal longitudinal connection of the steel pipe pile 1, and a method of using a mechanical joint 4 as shown in FIG. 2 (b) Various methods are possible, and an appropriate method may be selected according to the construction method of the pile, the length of the SC pile 2, and the like.

  FIG. 3 (c) as a comparative example shows a configuration in which a normal SC pile 2 and a steel pipe pile 1 having no protrusion on the inner peripheral surface are connected. In this case, the SC pile 2 and the steel pipe pile 1 are The cross section suddenly changes at the joint, and the cross section of the steel pipe pile 1 immediately below the joint tends to be a structural weak point.

  That is, in the SC pile 2 part, the load shared and transmitted by the steel pipe 2a and the concrete 2b is concentrated on the cross section of the steel pipe pile 1 at the joint, but at this time, only a simple axial force is present near the end of the steel pipe pile 1 In addition, the bending from the end plate 2d of the SC pile 2 may be a structural weak point.

  Therefore, in consideration of this, the steel pipe pile 1 has a plate thickness larger than the plate thickness necessary for transmitting the axial force, or requires structural measures such as arrangement of stiffeners. .

  3 (a) and 3 (b), in the lower part of the SC pile 2, the steel pipe 2a of the SC pile 2 shares all or most of the vertical load, in particular FIG. In consideration of the fact that the steel pipes 2a of the SC pile 2 are welded together in the configuration of b), it is desirable that the steel pipe 2a of the SC pile 2 is equal to or greater than the thickness of the steel pipe pile 1 to be joined thereto.

  The protrusion 2c can be formed by welding flat steel or steel bar, and the material is not particularly limited as long as it can transmit the load between the concrete 2b and the steel pipe 2a, but as shown in FIG. It is also possible to apply a weld molding projection in which the projection 2c is formed directly by a weld bead (corresponding to claim 8).

Preferred and dimensions example in FIG. 4, as the thickness t of the SC piles 2 of the steel pipe 2a at least 9 mm, projection width B ₀ is 6 to 10 mm, the projection height t ₀ is 8 to 12 mm.

Considering the concrete covering thickness of the SC pile 2 and the concrete filling property at the time of manufacture, the projection 2c having a very high height is not preferable, and the projection height t ₀ is desirably about 15 mm. Considering this fact, projection molding using a weld bead is suitable, and the projection material can be omitted, the manufacturing process can be shortened, and the cost can be reduced.

  In addition, it is also possible to apply a steel pipe with an internal protrusion, which is made of a steel plate provided with protrusions by rolling, thereby eliminating the need for protrusion welding.

  FIG. 5 shows an embodiment of the invention according to claim 2, wherein the outer diameter is larger than the outer diameter of the steel pipe pile 1 as the upper pile on the steel pipe pile 1 as the lower pile, and the diameter of the hollow portion. However, the SC pile 2 smaller than the outer diameter of the steel pipe pile 1 is connected.

  The point which uses the thing larger than the bending yield strength of the steel pipe pile 1 to which the bending yield strength under action axial force is joined as SC pile 2 is the same as that of the case of FIG. It is possible to select the optimum structure in consideration of various conditions such as the proof stress necessary for the SC pile 2 part, the pile construction method, the joining method of the SC pile 2 and the steel pipe pile 1, and the restrictions on the manufacture and transportation of the SC pile 2 it can.

  In this case as well, the steel pipe pile 1 and the SC pile 2 can be joined by welding in the same manner as in the case of a normal joint between normal piles. Alternatively, the SC pile 2 and the steel pipe pile 1 having a predetermined length may be joined in advance by factory welding or the like, and then carried into the site, and the longitudinal joint on the site may be formed by joining common steel pipe piles.

  Since the proof stress of the SC pile 2 varies depending on the material of the steel pipe 2a to be used, the plate thickness, and the strength of the concrete 2b, these combinations may be selected so that the required proof strength can be obtained.

  Further, in claim 2, since the SC pile 2 having a larger outer diameter than that of the steel pipe pile 1 is used, the SC pile 2 having a bending strength larger than that of the steel pipe pile 1 can be easily formed, and the material / sheet thickness of the steel pipe 2a, concrete 2b If the combination of strength is also taken into consideration, the bending strength can be greatly increased as compared with the steel pipe pile 1.

  Moreover, FIG. 6 is a case where the SC pile 2 in which the protrusion 2c is provided on the lower inner peripheral surface of the steel pipe 2a is applied in the invention according to claim 2, and corresponds to the embodiment of the invention according to claim 1. The SC pile 2 itself corresponds to the SC pile according to claim 4 or 5.

  FIG. 7 is an explanatory view of a load transmission mechanism in the invention according to claim 2.

  As shown in FIG. 5, when the SC pile 2 having an outer diameter larger than the diameter of the steel pipe pile 1 and a hollow portion smaller than the outer diameter of the steel pipe pile 1 is used, the cross section rapidly changes at the joint. However, since the steel pipe pile 1 is joined between the outer edge and the inner edge of the end plate 2d of the SC pile 2 as shown in FIG. 7, the bending transmitted from the end plate 2d to the vicinity of the end of the steel pipe pile 1 is bi-directional. Therefore, the vertical load can be stably transmitted to the steel pipe pile 1. That is, by adjusting the thickness and shape of the end plate 2d and the joining position of the steel pipe pile 1, smooth transmission of the vertical load can be realized.

  FIG. 8 shows an example (one side only) of the cross-sectional shape of the end plate 2d regarding the welding of the steel pipe pile 1 as the lower pile and the SC pile 2 as the upper pile in the invention according to claim 2. A projection 5 for guiding and backing is also provided at the place where the joints are joined.

  Further, the projecting portion 5 serves as a stiffener for increasing the rigidity of the end plate 2d and preventing deformation in vertical load transmission, and contributes to smooth load transmission to the steel pipe pile 1. It has become.

  FIG. 9 shows a steel pipe pile 1 as a lower pile and an SC as an upper pile in an embodiment of a foundation pile structure according to claim 3 (the whole structure is the same as in FIG. 1 or FIG. 5 and is omitted). The joint part of the pile 2 (corresponding to claim 6 or 7) is shown.

  In this example, the steel pipe 2e is integrated also on the inner surface side of the concrete 2b of the SC pile 2, and further, a protrusion 2f is provided on a portion of the outer peripheral surface of the inner surface side steel pipe 2e in contact with the concrete 2b, and one end is from the end of the concrete 2b. It has a configuration that protrudes a predetermined length. By connecting the steel pipe piles 1 having the same diameter as the protruding inner steel pipe 2e by welding 3 or the like, a foundation pile having an enlarged head is built.

  As the projection 2f of the inner surface side steel pipe 2e, for example, a projection formed by welding a flat bar or a steel bar, like the projection 2c on the inner peripheral surface of the steel pipe 2a of the SC pile 2 shown in FIG. 1, can be used. The material is not particularly limited as long as the load can be transmitted between the concrete 2b and the inner surface side steel pipe 2e. Moreover, the protrusion (welding molding protrusion) by the weld bead shown in FIG. 4 can also be applied.

  10 (a) to 10 (c) show another embodiment of the SC pile 2 (corresponding to claim 6 or 7) used in the foundation pile structure according to claim 3. FIG.

  FIG. 10 (a) shows an example in which a steel pipe provided with protrusions 2f on the outer peripheral surface is used for the inner steel pipe 2e. The steel pipe 2a on the outer peripheral surface side of the SC pile 2 has no protrusions. In FIG. 10 (a), a vertical pushing load can be transmitted from the SC pile 2 to the inner surface side steel pipe 2e by the outer peripheral surface projection 2f of the inner surface side steel pipe 2e, and the end plate 2d at the lower end of the SC pile 2 is omitted. Has been.

  In the case where there is no load in the drawing direction, the end plate 2d can be omitted as in this example, or the end plate 2d can be simplified as it only serves as a formwork for placing the concrete 2b during production.

  FIG.10 (b) is a case where the outer surface striped steel pipe shape | molded from a striped steel plate is used as the inner surface side steel pipe 2e instead of the inner surface side steel pipe 2e which provided the protrusion 2f in the SC pile 2 of FIG.

  By providing the protrusions 2c and 2f on the steel pipes 2a and 2e on both sides, it is possible to more stably transmit the push-in load in the vertical direction, and to smoothly transmit the load in the pull-out direction. . In this structure as well, the foundation pile with the head expanded can be constructed by connecting the steel pipe piles having the same diameter as the protruding inner steel pipe 2e as in the case of FIG.

  In the example of FIG. 10 (c), the end plate 2d at the lower end of the SC pile 2 and the inner surface side steel pipe 2e are fixed by welding 3 or the like, or an end plate having sufficient rigidity is used even if not fixed. The structure is such that the load can be stably transmitted even with respect to the load in the drawing direction.

  In addition, although the example of the structure which provided the end plate 2g in the head of the inner surface side steel pipe 2e is shown in FIG.10 (c), this utilizes the concrete 12 with which a hollow part head is filled at the time of a pile head process. Thus, the role of transmitting the vertical load to the concrete inner side steel pipe 2e is expected.

  11 (a) and 11 (b) show a load transmission mechanism when the SC pile 2 shown in FIGS. 10 (a) and 10 (b) is used.

  In the structure using the SC pile 2 of FIG. 10 (a) shown in FIG. 11 (a), the load transferred by the steel pipe 2a and the concrete 2b, which is shared by the steel pipe 2a and the concrete 2b, is gradually passed through 2f on the SC pile 2e. On the lower surface of the concrete 2b, the shared load of the concrete becomes zero, and everything is transmitted to the inner surface side steel pipe 2e and further to the steel pipe pile 1.

  In the structure using the SC pile 2 of FIG. 10 (b) shown in FIG. 11 (b), the transmission of the load becomes clearer and more stable. That is, among the loads transmitted and shared by the steel pipe 2a and the concrete 2b at the upper part of the SC pile 2, the shared load on the steel pipe 2a is transmitted to the concrete 2b by the inner peripheral surface projection 2c of the steel pipe 2a of the SC pile 2, And the shared load of the concrete 2b portion is transmitted to the inner surface side steel pipe 2e via the protrusion 2f on the outer peripheral surface, and further transmitted to the steel pipe pile 1.

  Further, in the structure of FIG. 11 (b), load transmission can be stably performed even with respect to the load in the drawing direction. In this case, the end plate 2d at the lower end of the SC pile 2 is not necessarily required from a structural point of view if a sufficient number of protrusions are secured on the steel pipes 2a, 2e on both sides, as in FIG. 11 (a). It is possible to rationalize such as omitting the end plate or using a simple end plate.

It is sectional drawing which shows one Embodiment of the invention which concerns on Claim 1. (a), (b) is sectional drawing which shows the junction part of the lower pile and upper pile in other embodiment of the invention which concerns on Claim 1, (c) shows the junction part of the lower pile and upper pile in a comparative example It is sectional drawing. (a), (b) is explanatory drawing of the load transmission mechanism in the invention which concerns on Claim 1, (c) is explanatory drawing of the load transmission mechanism in a comparative example. It is explanatory drawing of the processus | protrusion by a weld bead. It is sectional drawing which shows one Embodiment of the invention which concerns on Claim 2. It is sectional drawing which shows the junction part of the lower pile and upper pile in other embodiment of the invention which concerns on Claim 2. It is explanatory drawing of the load transmission mechanism in the invention which concerns on Claim 2. It is explanatory drawing of the junction part by welding of the lower pile and the upper pile in the invention which concerns on Claim 2. It is sectional drawing which shows the junction part of the lower pile and upper pile in one Embodiment of the invention which concerns on Claim 3. (a)-(c) is sectional drawing which shows other embodiment of the SC pile used by the invention which concerns on Claim 3. FIG. (a), (b) is explanatory drawing of the load transmission mechanism in the invention which concerns on Claim 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steel pipe pile, 2 ... SC pile, 2a ... Steel pipe, 2b ... Concrete, 2c ... Protrusion, 2d ... End plate, 2e ... Inner surface side steel pipe, 2f ... Protrusion, 2g ... End plate, 3 ... Welding, 4 ... Mechanical type Fittings,
11 ... Footing, 12 ... Concrete,
21 ... Upper part of the ground, 22 ... Supporting ground

Claims (8)

  As an upper pile or a part of the upper pile, an SC pile having a bending strength greater than that of the steel pipe pile is joined to the upper portion of the steel pipe pile, and one or more steps are provided at the lower part of the inner peripheral surface of the steel pipe constituting the SC pile. A foundation pile structure characterized by a step projection.   As an upper pile or as a part of the upper pile, an SC pile having a bending strength greater than that of the steel pipe pile is joined to the upper portion of the steel pipe pile, and the outer diameter of the steel pipe pile is smaller than the outer diameter of the SC pile. The foundation pile structure characterized by being larger than the diameter of the hollow part of this SC pile, and joining the upper end part of this steel pipe pile, and the end plate provided in the concrete edge part of the said SC pile by welding.   As an upper pile or as a part of the upper pile, an SC pile having a bending strength greater than that of the steel pipe pile is joined to the upper portion of the steel pipe pile, and the inner surface side steel pipe is integrated on the concrete inner surface side of the SC pile. And a lower portion of the inner surface side steel pipe projects a required length from an end portion of the concrete, and a lower end portion of the inner surface side steel pipe is joined to an upper end portion of the steel pipe pile.   An SC pile in which concrete is integrated with an inner peripheral surface of a steel pipe, wherein one or more continuous or discontinuous protrusions are provided on an inner peripheral surface of the end portion of the steel pipe.   The SC pile according to claim 4, wherein the protrusion is formed by a weld bead.   In a hollow SC pile in which concrete is integrated on the inner peripheral surface of the steel pipe, an inner surface side steel pipe is integrated on the concrete inner surface side of the SC pile, and at least one end of the inner surface side steel pipe is required from the end of the concrete. SC pile characterized by long protrusion.   The SC pile according to claim 6, wherein one or a plurality of steps of continuous or discontinuous protrusions are provided on the inner peripheral surface of the end of the steel pipe and / or the outer peripheral surface of the inner surface side steel pipe.   The SC pile according to claim 6 or 7, wherein a part or all of the protrusion is formed by a weld bead.

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