Pile foundation design method, pile foundation construction method, and pile foundation design system

Abstract

To provide a pile foundation design method, a pile foundation construction method, and a pile foundation design system which allow reduced variations of pile hole diameters and improved workability of the pile foundation.SOLUTION: A pile foundation design method is provided with a specification determination process for determining specifications of a plurality of pile holes in a pile foundation construction site and specifications of precast piles placed in the plurality of pile holes, respectively, to allocate pile holes with a same diameter of the pile hole to a plurality of the precast piles with different pile diameters.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a pile foundation design method, a pile foundation construction method, and a pile foundation design system. [Background technology]

[0002] Conventionally, a method for constructing a pile foundation has been known in which pile diameters are fixed or two or three types are used, while the pile hole diameter is set for each pile according to the tip bearing capacity (see, for example, Patent Document 1). According to the construction method disclosed in Patent Document 1, by reducing the number of pile types, the effort and cost of preparing piles with different diameters is eliminated, and workability is improved. Meanwhile, in this method, the obtained tip bearing capacity is changed by setting the ratio D2 / D1 of the pile hole diameter D2 to the pile diameter D1 in the range of 1.3 to 2.5. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-183510 A Summary of the Invention [Problem to be solved by the invention]

[0004] As disclosed in Patent Document 1, if the pile hole diameter is changed for each pile to change the tip bearing capacity, the number of types of pile holes will increase. If the number of types of pile holes increases, it will be time-consuming to change the setup, such as replacing the excavator or drill. In this case, the number of types of equipment and materials, such as the excavator and drill, will also increase, making the arrangement and management of the equipment and materials complicated. For this reason, if the pile hole diameter is changed for each pile, the workability will actually decrease. In view of the above-mentioned circumstances, an object of the present invention is to provide a pile foundation design method, a pile foundation construction method, and a pile foundation design system that reduce the number of pile hole diameter types and improve the workability of the pile foundation. [Means for solving the problem]

[0005] (1) A pile foundation design method according to at least one embodiment of the present invention includes: A specification setting process for setting specifications of a plurality of pile holes at a pile foundation construction site and specifications of prefabricated piles to be placed in the plurality of pile holes, In the specification setting step, pile holes having the same pile hole diameter are assigned to the precast piles having different pile diameters.

[0006] According to the above configuration (1), by allocating pile holes of the same pile hole diameter to a plurality of prefabricated piles with different pile diameters, i.e., by arranging prefabricated piles of different diameters for pile holes of the same pile hole diameter, the number of types of pile hole diameters can be reduced. As a result, according to the above configuration (1), the number of setup changes required to change the pile hole diameter is reduced, and the number of types of equipment and materials such as excavators and drills is reduced, making it easier to arrange and manage them, and improving the workability of the pile foundation.

[0007] (2) A pile foundation construction method according to at least one embodiment of the present invention includes: A pile hole excavation process of excavating a plurality of pile holes at one pile foundation construction site; A pile placing process for placing prefabricated piles in the pile holes, In the pile placing step, prefabricated piles having different pile diameters among the prefabricated piles are placed in pile holes having the same pile hole diameter among the plurality of pile holes. According to the above configuration (2), by arranging prefabricated piles of different diameters for pile holes of the same diameter, the number of types of pile hole diameters can be reduced. As a result, according to the above configuration (2), the number of setup changes required to change the pile hole diameter is reduced, and the number of types of equipment and materials such as excavators and drills is reduced, making it easier to arrange and manage them, and improving the workability of the pile foundation.

[0008] (3) A pile foundation design system according to at least one embodiment of the present invention, A specification setting unit for setting specifications of a plurality of pile holes at a pile foundation construction site and specifications of prefabricated piles to be placed in the plurality of pile holes, A database capable of registering a plurality of pile diameters of prefabricated piles that can be placed in a pile hole of a certain pile hole diameter in association with the pile hole diameter; The specification setting unit includes: The pile hole diameter set by the designer is used as the search value. Refer to the above database A plurality of pile diameters associated with the one pile hole diameter can be extracted by the above method, and the designer can select from the plurality of pile diameters extracted. said plurality of pile holes Among the pile holes of the same diameter The prefabricated piles are arranged in the Pile diameter It is configured to be selectable.

[0009] According to the above configuration (3), by referring to the database, multiple pile diameters can be extracted for one pile hole diameter, and the designer can easily select an appropriate pile diameter from the multiple extracted pile diameters. Therefore, the designer can easily design a pile foundation with good workability by reducing the number of types of pile hole diameters by placing prefabricated piles of different pile diameters in pile holes of the same pile hole diameter.

[0010] (4) In some embodiments, in the above configuration (3), The pile hole diameters of the plurality of pile holes at the one pile foundation construction site are configured to be the same. According to the above configuration (4), it is possible to easily design a pile foundation in which the pile holes at one pile foundation construction site have only one pile hole diameter, so that it is possible to easily design a pile foundation with better workability.

[0011] (5) In some embodiments, in the above configuration (3) or (4), At the one pile foundation construction site, an expansion ratio corresponding to the ratio of the pile hole diameter of the pile hole in which the precast pile is placed to the pile diameter of the precast pile is configured to be 1.0 or more and 2.0 or less. According to the above configuration (5), by setting the expansion ratio corresponding to the ratio of the pile hole diameter to the pile diameter to be 1.0 or more and 2.0 or less, the range of pile diameter options is wide even for the same pile hole diameter, and the vertical bearing capacity and horizontal bearing capacity obtained by combining each pile hole and precast pile can be appropriately changed.

[0012] (6) In some embodiments, in any one of the above configurations (3) to (5), As a specification of the prefabricated pile, a nodular pile having a shaft portion and a nodular portion provided on the shaft portion can be selected. According to the above configuration (6), by selecting a nodal pile as a precast pile, the vertical bearing capacity obtained by the combination of each pile hole and a precast pile can be increased, and even if the pile hole diameter is the same, the setting range of the vertical bearing capacity can be widened. Effect of the Invention

[0013] According to the present invention, there are provided a pile foundation design method, a pile foundation construction method, and a pile foundation design system that reduce the number of pile hole diameter types and improve the workability of the pile foundation. [Brief description of the drawings]

[0014] [Figure 1] 1 is a flowchart showing a schematic procedure of a pile foundation design method according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view showing a schematic part of the configuration of a pile foundation designed and constructed by the pile foundation design method of FIG. 1. [Diagram 3] 2 is a cross-sectional view showing a schematic part of the configuration of another pile foundation designed and constructed by the pile foundation design method of FIG. 1. [Figure 4] 2 is a cross-sectional view showing a schematic part of the configuration of another pile foundation designed and constructed by the pile foundation design method of FIG. 1. [Diagram 5] 1 is a flowchart showing a schematic procedure of a pile foundation construction method according to one embodiment of the present invention. [Figure 6] 1 is a diagram showing a schematic configuration of a pile foundation design system according to one embodiment of the present invention. [Figure 7] 7 is a table showing an example of a data set registered in a database of the pile foundation design system of FIG. 6. [Figure 8] 7 is a table showing another example of a data set registered in the database of the pile foundation design system of FIG. 6. [Figure 9] 7 is a table showing another example of a data set registered in the database of the pile foundation design system of FIG. 6. [Figure 10] FIG. 7 is a diagram roughly illustrating an example of a specification setting screen displayed by the pile foundation design system of FIG. 6, and is a diagram illustrating the specification setting screen in an initial state. [Figure 11] FIG. 7 is a diagram showing an example of a specification setting screen displayed by the pile foundation design system of FIG. 6, showing the specification setting screen in a state after the pile hole diameter in the first line is input. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0016] Fig. 1 is a flow chart showing a schematic procedure of a pile foundation design method according to an embodiment of the present invention (hereinafter, also simply referred to as a pile foundation design method). As shown in Fig. 1, the pile foundation design method includes a specification setting process S1 and a verification process S2. In the specification setting process S1, the specifications of a plurality of pile holes at one pile foundation construction site and the specifications of prefabricated piles to be placed in the plurality of pile holes, respectively, are set.

[0017] The specifications of a pile hole are the arrangement of multiple pile holes and the shape of each pile hole, and the shape of a pile hole is the diameter and length of the pile hole. In terms of shape, there are straight holes, enlarged holes, enlarged head holes, enlarged head holes, etc., and as for the shape of a pile hole, in the case of an enlarged head hole, the diameter and length of the enlarged part (bottom of the pile hole) and the diameter and length of the shaft part (part above the enlarged part) are set, in the case of an enlarged head hole, the diameter and length of the enlarged head part (top of the pile hole) and the diameter and length of the shaft part (part below the enlarged head part) are set, and in the case of an enlarged head hole, the diameter and length of the enlarged part, the diameter and length of the enlarged head part, and the diameter and length of the shaft part (part between the enlarged head part and the enlarged head part) are set.

[0018] The specifications of precast piles include the type, outer diameter and length of the precast pile, and in the case of joint piles, the type, outer diameter and length of each precast pile (e.g., upper pile, middle pile, lower pile). Types of precast piles, in terms of material, include steel pipe piles, SC piles (concrete piles with steel pipes), PC piles (prestressed concrete piles), PHC piles (high-strength prestressed concrete piles), PRC piles (high-strength prestressed reinforced concrete piles), etc., and in terms of shape, include straight piles (shank only), nodal piles (having a shaft and nodal parts), enlarged head piles (having a shaft and enlarged head part), enlarged base piles (having a shaft and enlarged base part), etc. Therefore, the outer diameter and length of a precast pile include the outer diameter and length of the shaft, nodal part, enlarged head part, and enlarged base part, respectively.

[0019] In the verification step S2, it is judged whether or not the combination of each pile hole and precast pile has a predetermined performance. The predetermined performance is, for example, vertical bearing capacity (tip bearing capacity and peripheral friction force) and horizontal resistance. If the judgment result shows that the combination of each pile hole and precast pile has the predetermined performance, the design is completed. On the other hand, if the judgment result shows that the combination of each pile hole and precast pile does not have the predetermined performance, the specification setting step S1 is executed again to set the specifications of the multiple pile holes at one pile foundation construction site and the specifications of the precast piles to be placed in each of the multiple pile holes. In other words, the specification setting step S1 is repeated until specifications having the predetermined performance are found.

[0020] Here, Fig. 2 is a cross-sectional view showing a schematic diagram of a part of the structure of a pile foundation designed and constructed by the pile foundation design method. In the pile foundation, a plurality of precast piles 1a, 1b are arranged in corresponding pile holes 3a, 3b. A base fixing liquid is poured into the bottom of the pile holes 3a, 3b, and the lower ends of the precast piles 1a, 1b are surrounded by a base fixing part 5 formed by the base fixing liquid and the hardened excavated soil. A pile circumferential liquid is poured above the base fixing part 5, and the part of the precast piles 1a, 1b above the base fixing part 5 is surrounded by a pile circumferential part 7 formed by the hardened pile circumferential liquid and the hardened excavated soil.

[0021] As can be seen from FIG. 2, in the pile foundation design method, in the specification setting process S1, pile holes 3a, 3b having the same pile hole diameter Dh are assigned to a plurality of precast piles 1a, 1b having different pile diameters Dp (Dpa, Dpb).

[0022] According to the pile foundation design method of the above configuration, by allocating pile holes 3a, 3b of the same pile hole diameter Dh to multiple prefabricated piles 1a, 1b of different pile diameters Dp, that is, by arranging prefabricated piles 1a, 1b of different pile diameters Dp to pile holes 3a, 3b of the same pile hole diameter Dh, the number of types of pile hole diameters Dh can be reduced. As a result, according to the pile foundation design method of the above configuration, the changeover work of excavators, excavation drills, etc. for changing the pile hole diameter Dh is reduced, and the arrangement and management of equipment and materials such as excavators and excavation drills is facilitated, improving the workability of the pile foundation.

[0023] On the other hand, when the pile diameters Dp are not uniform and there are many types, managing prefabricated piles with different pile diameters Dp becomes a problem. However, currently, prefabricated piles are assigned symbols indicating their specifications, and by using the symbols, they can be properly managed even if the pile diameters Dp of the prefabricated piles placed in each pile hole are different. It is preferable that the pile hole diameters Dh of all pile holes at one pile foundation construction site are the same, but as long as the number of pile diameter types is reduced and the work of changing over the excavator, drilling drill, etc. is reduced, it is sufficient that the pile hole diameters Dh of at least some of the pile holes are the same.

[0024] FIG. 3 is a cross-sectional view that illustrates a schematic diagram of a part of the configuration of another pile foundation designed and constructed by the pile foundation design method according to one embodiment of the present invention. The pile holes 3a and 3b in FIG. 2 are straight holes, but the pile holes 3c and 3d in FIG. 3 are enlarged holes. In this case, the pile holes 3c and 3d have an enlarged bottom portion 9 and a shaft portion 11 above the enlarged bottom portion 9, and the pile hole diameter Dh is the diameter of the enlarged bottom portion 9 or the base fixing portion 5 (base fixing portion diameter Dhe) and the diameter of the shaft portion 11 or the pile peripheral portion 7 (shaft diameter Dha). In this case, the pile hole diameter Dh being the same means that at least the shaft diameter Dha is the same, and preferably, the base fixing portion diameter Dhe is also the same. If at least the shaft diameter Dha is the same, the shaft portion 11 can be excavated by the same excavator and drill. Although not shown in the figure, even when the pile hole is an enlarged head hole or an enlarged bottom hole, the pile hole diameter being the same means that at least the shaft diameter is the same, and preferably the diameters of the enlarged bottom and head are also the same.

[0025] FIG. 4 is a cross-sectional view that shows a schematic view of a part of the configuration of another pile foundation designed and constructed by the pile foundation design method according to one embodiment of the present invention. The precast piles 1a and 1b in Figures 2 and 3 are straight piles, while the precast pile 1c in Figure 4 is a joint pile consisting of a nodal pile 13 as the lower pile, an enlarged head pile 15 as the middle pile, and a straight pile 17 as the upper pile.

[0026] 5 is a flowchart showing a schematic procedure of a pile foundation construction method according to one embodiment of the present invention (hereinafter, also simply referred to as a pile foundation construction method). The pile foundation construction method is for constructing a pile foundation designed by the above-mentioned pile foundation design method.

[0027] As shown in FIG. 5, the pile foundation construction method includes a pile hole excavation step S10, a foot protection liquid / pile surrounding liquid injection step S12, and a pile arrangement step S14. In the pile hole excavation step S10, a plurality of pile holes are excavated at one pile foundation construction site. In the step S12 of injecting the root hardening liquid and pile surrounding liquid, the root hardening liquid and pile surrounding liquid are injected into the pile hole. Usually, the root hardening liquid is injected after the pile surrounding liquid is injected, but the order may be reversed. In the pile placing step S14, precast piles are placed in the plurality of pile holes, respectively. Then, in the pile placing step S14, precast piles having different pile diameters are placed in the plurality of pile holes having the same pile hole diameter.

[0028] According to the pile foundation construction method configured as above, by placing prefabricated piles of different diameters in pile holes of the same pile hole diameter, the number of types of hole diameters can be reduced. This reduces the need for changeover work to change the pile hole diameter, and makes it easier to arrange and manage equipment and materials, improving the workability of the pile foundation. Incidentally, the above-mentioned pile foundation construction method is premised on the use of the pre-boring method among the embedding methods, but it goes without saying that the core excavation method may also be used.

[0029] 6 is a diagram showing a schematic configuration of a pile foundation design system according to one embodiment of the present invention (hereinafter, also simply referred to as a pile foundation design system). The pile foundation design system is suitable for use in the above-mentioned pile foundation design method. Specifically, as shown in FIG. 6, the pile foundation design system includes a specification setting unit 20, a verification unit 22, and a database 24.

[0030] The specification setting unit 20 is a functional unit realized by the computer 26 executing a program, and the computer 26 has a general configuration, i.e., a CPU (Central Processing Unit), a memory, an external storage device, etc. The specification setting unit 20 is used by a pile foundation designer to operate the computer 26 via a user interface to set the specifications of a plurality of pile holes at one pile foundation construction site and the specifications of prefabricated piles to be placed in each of the plurality of pile holes.

[0031] The verification unit 22 is also a functional unit realized by the computer 26 executing a program, and judges whether or not the pile foundation has a predetermined performance (vertical bearing capacity and horizontal bearing capacity) based on the specifications of the pile holes set by the specification setting unit 20 and the specifications of the prefabricated piles to be placed in the pile holes, respectively. The verification unit 22 may verify the performance of the pile foundation by the pile foundation designer operating the computer 26 via a user interface, but may also be configured to perform the verification semi-automatically or fully automatically.

[0032] The database 24 may be stored in an external storage device of the computer 26, but in this embodiment, it is stored in an external storage device 28 that is communicatively connected to the computer 26, and the computer 26 can read and process the contents of the database 24. The database 24 is composed of a plurality of data sets, and in each data set, a pile hole diameter is associated (linked) with a plurality of pile diameters of precast piles that can be placed in a pile hole of the same diameter. The specification setting unit 20 is configured to be able to refer to the database 24 and extract a plurality of pile diameters associated with the pile hole diameter set by the designer as a search value. The designer can select an appropriate pile diameter from the extracted plurality of pile diameters.

[0033] According to the pile foundation design system configured as above, by referring to the database 24, multiple pile diameters can be extracted for one pile hole diameter, and the designer can easily select an appropriate pile diameter from the multiple extracted pile diameters. Therefore, the designer can easily design a pile foundation with good workability by reducing the number of types of pile hole diameters by placing prefabricated piles of different pile diameters in pile holes of the same pile hole diameter. In addition, when implementing the pile foundation design method of Figure 1 using the pile foundation design system configured as described above, if the necessary dataset is not registered in the database 24, a dataset registration step can be performed to register the dataset in advance in the database 24 before implementing the specification setting step S1.

[0034] 7 to 9 are tables that show a schematic representation of part of the contents of the data set in the database 24. In each of the tables, the hole shape is an enlarged hole, the precast pile is a nodular pile, and the diameter Dhe of the base portion is added to the shaft diameter Dha by 100 mm, 200 mm, and 300 mm, respectively. In addition, in the tables, only the diameter Dhe of the base portion and the diameter Dpn of the nodular portion linked to the shaft diameter Dha are shown as the pile hole diameter Dh, but it goes without saying that the diameter of the enlarged head of the pile hole may be registered as the pile hole diameter Dh, and the shaft diameter Dpa and the diameter of the enlarged head of the precast pile may be registered as the pile diameter Dp.

[0035] 7 to 9 show, for reference, the range of the expansion ratio corresponding to the ratio Dh / Dp of the pile hole diameter Dh to the pile diameter Dp of a precast pile that can be placed in the pile hole of the pile hole diameter Dh. In this embodiment, however, Dh / (Dp+50) is adopted as the expansion ratio approximately equivalent to the ratio Dh / Dp, but the ratio Dh / Dp itself may be used.

[0036] In some embodiments, in the pile foundation design system having the above configuration, the expansion ratio Dh / (Dp+50) at one pile foundation construction site is configured to be 1.0 or more and 2.0 or less. For this purpose, each data set in the database 24 is linked to one pile hole diameter Dh and multiple pile diameters Dp so that the expansion ratio Dh / (Dp+50) is 1.0 or more and 2.0 or less, as illustrated in Figs. 7 to 9.

[0037] According to the pile foundation design system configured as above, by setting the expansion ratio Dh / (Dp+50), which corresponds to the ratio of the pile hole diameter Dh to the pile diameter Dp, to be 1.0 or more and 2.0 or less, the range of pile diameter options is wide even for the same pile hole diameter, and the vertical bearing capacity and horizontal resistance capacity obtained by combining each pile hole and precast pile can be appropriately changed. In each data set in Figures 7 to 9, the minimum pile diameter Dp associated with each pile hole diameter Dh is set so that the expansion ratio Dh / (Dp+50) does not exceed 2.0, but the minimum pile diameter Dp may also be set so that the difference between the minimum pile diameter Dp and the pile hole shaft diameter Dha does not exceed 500 mm or 400 mm.

[0038] In some embodiments, in the pile foundation design system of the above configuration, the specification setting unit 20 is configured to preferentially select pile hole diameters that are linked to at least three or more, preferably four or more, and more preferably five or more pile diameters. According to the above configuration, at least three or more, preferably four or more, and more preferably five or more pile diameters can be selected, so that the number of pile hole diameter types can be reduced as much as possible, and the work of changing over the excavator and drill can be reduced as much as possible.

[0039] 7 to 9, the ratio of the diameter Dhe of the base protection portion to the diameter Dha of the shaft portion (hole enlargement ratio) Dhe / Dha is shown for each pile hole diameter Dh for reference. In some embodiments, the pile foundation design system having the above-mentioned configuration is configured to exclude combinations of pile hole diameters and pile diameters in which the expansion ratio Dhe / Dha exceeds a predetermined value, for example, 1.4. For this purpose, the relevant data set may be removed from the database 24, or the specification setting unit 20 may calculate the expansion ratio Dhe / Dha to exclude such combinations from being set. According to the above configuration, by limiting the hole expansion ratio Dhe / Dha to a predetermined value or less, the difference in drilling diameter between the shaft diameter and the expanded bottom diameter is suppressed, so that it is possible to reliably drill the shaft and expanded bottom of the pile hole continuously using a single mechanical expansion drill.

[0040] 10 and 11 are schematic diagrams showing an example of a specification setting screen displayed on the monitor by the specification setting unit 20. Fig. 10 shows the initial state, and Fig. 11 shows the state when the joint diameter is being input after the pile hole diameter and the foot protection part diameter of the first line of data are input. The specification setting screen has input fields for the pile hole diameter, the type of precast pile, and the pile diameter.

[0041] In some embodiments, the specification setting unit 20 is configured so that when the pile diameter of one pile hole is set, the pile diameters of the other pile holes are set to the same value. For example, as shown in Fig. 11, when the designer inputs the pile hole diameter and the foot protection part diameter of the first row on the specification setting screen, the pile hole diameters and the foot protection part diameters of the remaining rows are automatically set to the same value. This saves the designer the trouble of inputting the pile hole diameters and the foot protection part diameters of the remaining rows one by one. The automatically set pile hole diameter and foot protection part diameter may be changed later by the designer. In other words, as long as the number of pile hole diameter types is reduced and the changeover work of the excavator and the excavation drill is reduced, it is not necessary for all pile holes to have the same pile hole diameter.

[0042] 11, the specification setting unit 20 can display, for example, a pull-down menu 30 on the setting input screen as a means (option display means) for extracting pile diameters of precast piles that can be placed in pile holes of the input pile hole diameter and displaying them as options. By selecting an appropriate pile diameter from the options displayed in the pull-down menu 30, the designer can easily select and set pile diameters of precast piles that can be placed in pile holes of any pile hole diameter without having to check each one. In addition, the specification setting screens in Figures 10 and 11 are provided with input fields for the shaft diameter and base protection section diameter as the pile hole diameter, and the shaft diameter and node diameter as the pile diameter of a precast pile, but it goes without saying that input fields for the pile hole and the enlarged head diameter of a precast pile may also be provided.

[0043] In some embodiments, the pile foundation design system having the above-mentioned configuration is configured so that the pile hole diameters of a plurality of pile holes at one pile foundation construction site are the same. For this purpose, for example, a check box 32 may be provided on the specification setting screen of the pile foundation design system as a means for the designer to select whether or not to fix the pile hole diameter. The designer can make the pile hole diameters of a plurality of pile holes the same by clicking the check box 32. According to the above configuration, it is possible to easily design a pile foundation in which the pile holes at one pile foundation construction site have only one pile hole diameter, so that a pile foundation with even better workability can be easily designed.

[0044] In some embodiments, in the pile foundation design system configured as described above, a nodular pile having a shaft portion and a nodular portion provided on the shaft portion can be selected as a specification of a prefabricated pile. According to the above configuration, by selecting a nodular pile as the precast pile, the outer peripheral surface of the precast pile becomes larger and the unity between the base fixing portion 5 and the pile peripheral portion 7 on the outer peripheral surface of the precast pile is increased, so that when evaluating the vertical bearing capacity, it becomes possible to take into consideration the frictional resistance of the outer peripheral surfaces of the base fixing portion 5 and the pile peripheral portion 7 to a greater extent. As a result, the vertical bearing capacity of the precast pile can be increased, and the setting range of the vertical bearing capacity can be widened even if the pile hole diameter is the same. In addition, nodular piles include not only PHC piles and the like with nodular sections, but also steel pipe piles and SC piles with metal ribs.

[0045] Finally, the present invention is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications. [Explanation of symbols]

[0046] 1a, 1b, 1c Prefabricated piles 3a,3b,3c,3d Pile hole 5 Root protection section 7 Pile circumference 9. Enlarged base 11 Shaft 13 section stake 15 Expanded pile 17 Straight Stakes 20 Specification Setting Section 22 Inspection Department 24 Database 26 Computers 28 Storage device 30 Drop-down Menu 32 Checkboxes

Claims

1. A specification setting process for setting specifications of a plurality of pile holes at a pile foundation construction site and specifications of prefabricated piles to be placed in the plurality of pile holes, In the specification setting step, the pile holes having the same pile hole diameter are assigned to the plurality of prefabricated piles having different pile diameters. A pile foundation design method comprising the steps of:

2. A pile hole excavation process of excavating a plurality of pile holes at one pile foundation construction site; A pile placing process of placing prefabricated piles in the plurality of pile holes, In the pile arrangement step, prefabricated piles having different pile diameters are arranged in pile holes having the same pile hole diameter among the plurality of pile holes. A pile foundation construction method characterized by the above.

3. A specification setting unit for setting specifications of a plurality of pile holes at a pile foundation construction site and specifications of prefabricated piles to be placed in the plurality of pile holes, A database capable of registering a plurality of pile diameters of prefabricated piles that can be placed in a pile hole of a certain pile hole diameter in association with the pile hole diameter; The specification setting unit is configured to be able to extract a plurality of pile diameters associated with a certain pile hole diameter set by a designer by referring to the database as a search value, and to be able to select pile diameters of the prefabricated piles to be placed in the pile holes having the same pile hole diameter among the plurality of pile holes from the extracted pile diameters. A pile foundation design system characterized by the above.

4. The pile foundation design system according to claim 3, characterized in that the pile holes at the one pile foundation construction site are configured to have the same pile hole diameter.

5. The pile foundation design system according to claim 3 or 4, characterized in that, at the one pile foundation construction site, an expansion ratio corresponding to the ratio of the pile hole diameter of the pile hole in which the precast pile is placed to the pile diameter of the precast pile is configured to be 1.0 or more and 2.0 or less.

6. The pile foundation design system according to any one of claims 3 to 5, characterized in that a nodular pile having a shaft portion and a nodular portion provided on the shaft portion can be selected as a specification of the precast pile.

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