Construction method of cast-in-site concrete pile

Abstract

To provide a construction method of a cast-in-site concrete pile capable of suppressing deterioration of a concrete state upon construction of the cast-in-site concrete pile.SOLUTION: A construction method of a cast-in-site concrete pile comprises: a first tremie pipe pulling-up process stopping supply of concrete in the first tremie pipe 20 and pulling up a first tremie pipe 20 to separate an upper end side of the first tremie pipe 20 as filling concrete into a pile hole 10 through a second tremie pipe 30; and a second tremie pipe pulling-up process stopping supply of concrete in the second tremie pipe 30 and pulling up the second tremie pipe 30 to separate an upper end side of the second tremie pipe 30 as filling concrete into a pile hole 10 through the first tremie pipe 20, in which concrete is filled into the pile hole 10 through the first tremie pipe 20 and the second tremie pipe 30 inserted in the pile hole 10.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for constructing a cast-in-place concrete pile. [Background technology]

[0002] BACKGROUND ART When constructing a seabed foundation, an underwater concrete pouring method is known in which concrete is poured underwater (see, for example, Patent Document 1).

[0003] Also, a construction method for cast-in-place concrete piles is known in which concrete is poured into a pile hole filled with a stabilizing liquid using a tremie pipe (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 06-322764 [Patent Document 2] Japanese Patent Application Publication No. 08-184035 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, if the insertion length of the lower end of the tremie pipe into the concrete poured in the pile hole becomes too long, the flow resistance of the concrete poured from the lower end of the tremie pipe increases, and there is a possibility that the tremie pipe may become clogged, for example. Therefore, the tremie pipes are pulled up in order so that the insertion length of the lower end into the concrete does not exceed a predetermined value (upper limit). At this time, the supply of concrete to the tremie pipe is stopped, and the upper end of the pulled-up tremie pipe is cut off.

[0006] However, if pouring concrete into the pile hole is interrupted every time the tremie pipe is pulled up and its upper end is severed, the construction time will be extended and there is a possibility that the concrete properties such as slump will deteriorate.

[0007] In consideration of the above, the present invention aims to suppress deterioration of concrete properties during construction of cast-in-place concrete piles. [Means for solving the problem]

[0008] The method for constructing a cast-in-place concrete pile according to claim 1 is a method for constructing a cast-in-place concrete pile in which concrete is poured into a pile hole using a first tremie pipe and a second tremie pipe inserted into the pile hole, and comprises: a first tremie pipe pulling-up step in which the supply of concrete to the first tremie pipe is stopped, and concrete is poured into the pile hole via the second tremie pipe while pulling up the first tremie pipe to sever the upper end of the first tremie pipe; and a second tremie pipe pulling-up step in which the supply of concrete to the second tremie pipe is stopped, and concrete is poured into the pile hole via the first tremie pipe while pulling up the second tremie pipe to sever the upper end of the second tremie pipe.

[0009] According to the construction method for a cast-in-place concrete pile of claim 1, first, in the first tremie pipe pulling-up process, while pouring concrete into the pile hole through the second tremie pipe, the supply of concrete to the first tremie pipe is stopped, and the first tremie pipe is pulled up to cut off the upper end side of the first tremie pipe.

[0010] Next, in the second tremie pipe pulling-up process, while pouring concrete into the pile hole through the first tremie pipe, the supply of concrete to the second tremie pipe is stopped, and the second tremie pipe is pulled up to cut off the upper end side of the second tremie pipe.

[0011] In this way, in the present invention, the first and second tremie pipes are successively pulled up and their upper ends severed without interrupting the pouring of concrete into the pile hole. This shortens the construction time compared to a construction method in which pouring of concrete into the pile hole is interrupted every time the tremie pipes are pulled up and their upper ends severed. This makes it possible to suppress deterioration of concrete properties such as slump.

[0012] The method for constructing a cast-in-place concrete pile according to claim 2 is the method for constructing a cast-in-place concrete pile according to claim 1, wherein the first tremie pipe and the second tremie pipe are connected to a concrete supply pipe via an open-close branch pipe, and in the first tremie pipe pulling-up step, the supply of concrete to the first tremie pipe is stopped by closing the first tremie pipe side of the open-close branch pipe, and in the second tremie pipe pulling-up step, the supply of concrete to the second tremie pipe is stopped by closing the second tremie pipe side of the open-close branch pipe.

[0013] According to the cast-in-place concrete pile construction method of claim 2, in the first tremie pipe pulling up step, the first tremie pipe side of the openable branch pipe is closed to stop the supply of concrete to the first tremie pipe. Also, in the second tremie pipe pulling up step, the second tremie pipe side of the openable branch pipe is closed to stop the supply of concrete to the second tremie pipe.

[0014] In this way, in the present invention, by operating the open / close branch pipe, the tremie pipe for pouring concrete can be easily switched between the first tremie pipe and the second tremie pipe.

[0015] The method for constructing a cast-in-place concrete pile according to claim 3 is the method for constructing a cast-in-place concrete pile according to claim 1 or claim 2, further comprising a parallel pouring step of pouring concrete into the pile hole using the first tremie pipe and the second tremie pipe.

[0016] According to the cast-in-place concrete pile construction method of claim 3, in the parallel pouring step, concrete is poured into the pile hole via the first tremie pipe and the second tremie pipe. As a result, in the present invention, compared to pouring concrete into the pile hole via either the first tremie pipe or the second tremie pipe, it is possible to suppress unevenness of the concrete poured into the pile hole and improve the filling ability of the concrete into gaps in, for example, reinforcing bar cages.

[0017] The method for constructing a cast-in-place concrete pile according to claim 4 is a method for constructing a cast-in-place concrete pile in which concrete is poured into a pile hole using a first tremie pipe and a second tremie pipe inserted into the pile hole, wherein the first tremie pipe and the second tremie pipe each have a plurality of pipes that are connected in an axially separable manner, and the first tremie pipe and the second tremie pipe have portions where the connecting portions of the pipes are offset in the axial direction while one ends of the pipes are aligned, and the method comprises a first tremie pipe pulling-up step of stopping the supply of concrete to the first tremie pipe and pulling up the first tremie pipe to sever the upper end side of the first tremie pipe at the connecting portion of the pipes while pouring concrete into the pile hole via the second tremie pipe, and a second tremie pipe pulling-up step of stopping the supply of concrete to the second tremie pipe and pulling up the second tremie pipe to sever the upper end side of the second tremie pipe at the connecting portion of the pipes while pouring concrete into the pile hole via the first tremie pipe.

[0018] According to the cast-in-place concrete pile construction method of claim 4, the first tremie pipe and the second tremie pipe each have a plurality of pipes that are connected in an axially separable manner. Also, the first tremie pipe and the second tremie pipe have a portion where the connecting portion of the pipes is shifted in the axial direction when one end of each pipe is aligned.

[0019] First, in the first tremie pipe pulling-up process, while pouring concrete into the pile hole through the second tremie pipe, the supply of concrete to the first tremie pipe is stopped, and the first tremie pipe is pulled up to sever the upper end side of the first tremie pipe at the piping connection portion.

[0020] Next, in the second tremie pipe pulling-up process, while pouring concrete into the pile hole through the first tremie pipe, the supply of concrete to the second tremie pipe is stopped, and the second tremie pipe is pulled up to sever the upper end side of the second tremie pipe at the piping connection part.

[0021] In this way, in the present invention, the first and second tremie pipes are successively pulled up without interrupting the pouring of concrete into the pile hole, and their upper ends are severed at the pipe joints. This shortens the construction time compared to a construction method in which pouring of concrete into the pile hole is interrupted every time the tremie pipes are pulled up and their upper ends are severed at the pipe joints. This makes it possible to suppress deterioration of concrete properties such as slump.

[0022] Furthermore, as described above, the first and second tremie pipes have a portion where the connecting portion of the pipe is misaligned in the axial direction when one end of each pipe is aligned. This allows the amount of lifting (pulling length) of the first and second tremie pipes to be changed, thereby improving workability. [Effects of the Invention]

[0023] As described above, according to the present invention, deterioration of concrete properties can be suppressed during construction of a cast-in-place concrete pile. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 2 is an elevation view showing a first tremie pipe and a second tremie pipe used in a construction method for a cast-in-place concrete pile according to one embodiment. [Figure 2] 1 is a vertical cross-sectional view showing a construction process of a construction method for a cast-in-place concrete pile according to one embodiment. FIG. [Figure 3] 1 is a vertical cross-sectional view showing a construction process of a construction method for a cast-in-place concrete pile according to one embodiment. FIG. [Figure 4] 1 is a vertical cross-sectional view showing a construction process of a construction method for a cast-in-place concrete pile according to one embodiment. FIG. [Figure 5] 1 is a vertical cross-sectional view showing a construction process of a construction method for a cast-in-place concrete pile according to one embodiment. FIG. [Figure 6] 1 is a vertical cross-sectional view showing a construction process of a construction method for a cast-in-place concrete pile according to one embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment will be described with reference to the drawings.

[0026] (tremie tube) As shown in Fig. 1, the method for constructing a cast-in-place concrete pile according to this embodiment uses two tremie pipes: a first tremie pipe 20 and a second tremie pipe 30. The first tremie pipe 20 and the second tremie pipe 30 have, as an example, the same axial length (total length). The first tremie pipe 20 and the second tremie pipe 30 have, as an example, the same diameter.

[0027] The axial lengths (total lengths) of the first tremie tube 20 and the second tremie tube 30 do not have to be the same and may be different. Furthermore, the diameters of the first tremie tube 20 and the second tremie tube 30 do not have to be the same and may be different.

[0028] The first tremie pipe 20 and the second tremie pipe 30 each have a plurality of pipes 40, 42 that are connected in an axially separable manner. Specifically, the first tremie pipe 20 and the second tremie pipe 30 each have two types of pipes 40, 42 with different lengths. Furthermore, each of the first tremie pipe 20 and the second tremie pipe 30 has two pipes 40 and three pipes 42.

[0029] The pipes 40, 42 that make up the first tremie pipe 20 are an example of first pipes, and the pipes 40, 42 that make up the second tremie pipe 30 are an example of second pipes.

[0030] Each of the pipes 40, 42 is formed in a cylindrical shape with the same diameter, and both axial ends are formed as connecting portions J such as threaded portions. These connecting portions J allow adjacent pipes 40 to be connected to each other, adjacent pipes 42 to each other, or adjacent pipes 40 and 42 to be connected in a detachable manner.

[0031] The pipe 40 is a short pipe having an axial length shorter than that of the pipe 42. In other words, the pipe 42 is a long pipe having an axial length longer than that of the pipe 40. In the present embodiment, as an example, the axial length of the pipe 42 is approximately three times the axial length of the pipe 40.

[0032] Here, the arrangement of the pipes 40, 42 differs between the first tremie pipe 20 and the second tremie pipe 30 depending on the lifting order, which will be described later. As a result, when one end (lower end) of the first tremie pipe 20 and the second tremie pipe 30 is aligned with each other, the connecting portion J of the pipes 40, 42 has a portion that is rubbed in the axial direction.

[0033] Specifically, the first tremie pipe 20 is arranged in the following order from top to bottom: pipe 40, two pipes 42, pipe 40, and pipe 42. On the other hand, the second tremie pipe 30 is arranged in the following order from top to bottom: two pipes 40 and three pipes 42. As a result, the positions of the third connecting portion J (separating portion) from the top of the first tremie pipe 20 and the second tremie pipe 30 are offset in the axial direction.

[0034] 2 shows the initial state of the first tremie pipe 20 and the second tremie pipe 30 inserted into the pile hole 10 formed in the ground G. The first tremie pipe 20 and the second tremie pipe 30 are arranged in the pile hole 10 with a predetermined distance between them. In addition, in the initial state, the lower ends of the first tremie pipe 20 and the second tremie pipe 30 are located at approximately the same depth.

[0035] (Open and close branch piping) A concrete supply pipe (concrete pressure pipe) 52 is connected to the upper end of each of the first tremie pipe 20 and the second tremie pipe 30 via an open / close branch pipe 50. A concrete pump or the like (not shown) is connected to the concrete supply pipe 52, and concrete (ready-mixed concrete) is supplied to the open / close branch pipe 50 via the concrete supply pipe 52 by operating the concrete pump or the like.

[0036] The open / close branch piping 50 has a main pipe section 50A, a first branch pipe section 50B1, and a second branch pipe section 50B2. A concrete supply pipe 52 is connected to the main pipe section 50A. A first branch pipe section 50B1 and a second branch pipe section 50B2 branch off from this main pipe section 50A. A first tremie pipe 20 is connected to the first branch pipe section 50B1 via a connecting hose 54, and a second tremie pipe 30 is connected to the second branch pipe section 50B2 via a connecting hose 54.

[0037] The first branch pipe section 50B1 is provided with a first shutter (shutter valve) 60 that opens and closes the first branch pipe section 50B1. Closing the first branch pipe section 50B1 with this first shutter 60 stops the concrete (ready-mixed concrete) from being supplied from the concrete supply pipe 52 to the first tremie pipe 20. On the other hand, opening the first branch pipe section 50B1 with the first shutter 60 allows concrete to be supplied from the concrete supply pipe 52 to the first tremie pipe 20.

[0038] Similarly, the second branch pipe section 50B2 is provided with a second shutter (shutter valve) 62 that opens and closes the second branch pipe section 50B2. Closing the second branch pipe section 50B2 with this second shutter 62 stops the concrete (ready-mixed concrete) from being supplied from the concrete supply pipe 52 to the second tremie pipe 30. On the other hand, opening the second branch pipe section 50B2 with the second shutter 62 allows concrete to be supplied from the concrete supply pipe 52 to the second tremie pipe 30.

[0039] (Cast-in-place concrete pile construction method) Next, an example of a construction method for a cast-in-place concrete pile according to this embodiment will be described.

[0040] As described above, FIG. 2 shows the initial state of the first tremie pipe 20 and the second tremie pipe 30 inserted into the pile hole 10.

[0041] A standpipe 12 is inserted into the upper end of the pile hole 10. The standpipe 12 is formed in a cylindrical shape and is inserted into the upper end of the pile hole 10 with its upper end protruding upward from the pile hole 10. A reinforcing bar cage 14 is inserted into the pile hole 10. The reinforcing bar cage 14 is formed in a cylindrical shape and is arranged below the standpipe 12.

[0042] The pile hole 10 is filled with a stabilizing solution (not shown). The stabilizing solution, the standpipe 12, and the reinforcing bar cage 14 may be provided as needed, and may be omitted as appropriate.

[0043] (Parallel pouring process) First, the parallel pouring process will be described. In the parallel pouring process, as shown in Figure 2, from the initial state of the first tremie pipe 20 and the second tremie pipe 30, the first shutter 60 and the second shutter 62 of the open / close type branch pipe 50 are opened, and a concrete pump (not shown) and the like are operated.

[0044] As a result, concrete is supplied to the first tremie pipe 20 and the second tremie pipe 30 from the concrete supply pipe 52 via the open / close branch pipe 50, and concrete (hereinafter referred to as "placed concrete") 16 is poured (discharged) from the lower ends of the first tremie pipe 20 and the second tremie pipe 30 to the bottom of the pile hole 10. Then, as the poured concrete 16 gradually pours up from the bottom of the pile hole 10, the lower ends of the first tremie pipe 20 and the second tremie pipe 30 are buried (inserted) in the poured concrete 16.

[0045] As a result, in this embodiment, compared to when concrete is poured into the pile hole 10 from either the first tremie pipe 20 or the second tremie pipe 30, the bias of the poured concrete 16 poured into the pile hole 10 is suppressed, and the filling ability of the poured concrete 16 into the gaps in the reinforcing bar cage 14 is improved.

[0046] In this embodiment, as an example, the amounts of concrete poured into the pile hole 10 from the first tremie pipe 20 and the second tremie pipe 30 are set to be the same (1:1).

[0047] Here, if the insertion length L of the lower ends of the first tremie pipe 20 and the second tremie pipe 30 into the poured concrete 16 becomes shorter, for example, the concrete ejected from the lower ends of the first tremie pipe 20 and the second tremie pipe 30 may rise along the outer surfaces of the first tremie pipe 20 and the second tremie pipe 30 and spread from the pouring surface 16S of the poured concrete 16.

[0048] On the other hand, if the insertion length L of the lower ends of the first tremie pipe 20 and the second tremie pipe 30 into the poured concrete 16 becomes longer, the flow resistance of the concrete poured from the lower ends of the first tremie pipe 20 and the second tremie pipe 30 increases, and there is a possibility that the first tremie pipe 20 and the second tremie pipe 30 may become clogged, for example.

[0049] Therefore, in this embodiment, concrete is poured into the pile hole 10 while the first tremie pipe 20 and the second tremie pipe 30 are pulled up in sequence so that the insertion length L of the lower ends of the first tremie pipe 20 and the second tremie pipe 30 into the poured concrete 16 is not less than a lower limit value and not more than an upper limit value.

[0050] The lower limit of the insertion length L of the lower end of the first tremie pipe 20 and the second tremie pipe 30 is, for example, 2 mm, and the upper limit is, for example, 9 mm. The amount of concrete supplied from the concrete supply pipe 52 to the open / close branch pipe 50 is, for example, constant.

[0051] (First tremie tube pulling process) Next, the first tremie pipe pulling-up step will be described. In the first tremie pipe pulling-up step, as described above, the first tremie pipe 20 is pulled up and the upper end side of the first tremie pipe 20 is severed while concrete is being poured into the pile hole 10 by the second tremie pipe 30 so that the insertion length L of the lower ends of the first tremie pipe 20 and the second tremie pipe 30 into the poured concrete 16 is not less than a lower limit value and not more than an upper limit value.

[0052] Specifically, as shown in Figure 3, first, the first branch pipe section 50B1 on the first tremie pipe 20 side of the open / close branch piping 50, i.e., the first shutter 60, is used to close the first branch pipe section 50B1, thereby stopping the supply of concrete from the concrete supply pipe 52 to the first tremie pipe 20. At this time, the second shutter 62 leaves the second branch pipe section 50B2 open. As a result, concrete is supplied from the concrete supply pipe 52 to the second tremie pipe 30, and concrete is continuously poured into the pile hole 10 via the second tremie pipe 30.

[0053] In this state, the connecting hose 54 is removed from the upper end of the first tremie pipe 20, and the first tremie pipe 20 is pulled up using a crane or the like (not shown). At this time, the first tremie pipe 20 is pulled up by the length of one piece of piping 40, and one piece of piping 40 is severed from the upper end side of the first tremie pipe 20 at the connecting part J. Then, the first branch pipe part 50B1 is connected via the connecting hose 54 to the upper end of the first tremie pipe 20, whose overall length has been shortened.

[0054] As a result, in this embodiment, the first tremie pipe 20 can be pulled up and the upper end side of the first tremie pipe 20 can be severed at the connection part J of the pipes 40, 42 without interrupting the pouring of concrete into the pile hole 10.

[0055] (Second tremie tube pulling process) Next, the second tremie pipe pulling-up step will be described. In the second tremie pipe pulling-up step, concrete is poured into the pile hole 10 using the first tremie pipe 20, and the second tremie pipe 30 is pulled up to cut off the upper end side of the second tremie pipe 30, so that the insertion length L of the lower ends of the first tremie pipe 20 and the second tremie pipe 30 into the poured concrete 16 is equal to or greater than a lower limit value and equal to or less than an upper limit value.

[0056] 4, first, the first branch pipe section 50B1 on the first tremie pipe 20 side of the open / close branch piping 50, i.e., the first shutter 60 is used to open the opening, thereby supplying concrete from the concrete supply pipe 52 to the first tremie pipe 20. As a result, concrete is supplied from the concrete supply pipe 52 to the first tremie pipe 20, and the concrete is poured into the pile hole 10 via the first tremie pipe 20.

[0057] In addition, by closing the second branch pipe section 50B2 on the second tremie pipe 30 side of the open / close branch piping 50, i.e., by using the second shutter 62, the supply of concrete from the concrete supply pipe 52 to the second tremie pipe 30 is stopped.

[0058] In this state, the connecting hose 54 is removed from the upper end of the second tremie pipe 30, and the second tremie pipe 30 is pulled up using a lifting machine or the like (not shown). At this time, the second tremie pipe 30 is pulled up by a length equivalent to two pieces of pipe 40, and two pieces of pipe 40 are separated from the upper end side of the second tremie pipe 30 at the connecting part J. In other words, the amount (pulling length) of the second tremie pipe 30 is greater than the amount of the first tremie pipe 20. As a result, the lower end of the second tremie pipe 30 is positioned higher than the lower end of the first tremie pipe 20.

[0059] Then, the second branch pipe section 50B2 is connected to the upper end of the second tremie pipe 30, whose overall length has been shortened, via the connecting hose 54. As a result, in this embodiment, the second tremie pipe 30 can be pulled up and the upper end side of the second tremie pipe 30 can be severed at the connecting section J of the piping 40, 42 without interrupting the pouring of concrete into the pile hole 10.

[0060] In this embodiment, the first branch pipe section 50B1 is opened by the first shutter 60 of the open / close type branch pipe 50, and then the second branch pipe section 50B2 is closed by the second shutter 62 of the open / close type branch pipe 50. However, the first shutter 60 and the second shutter 62 of the open / close type branch pipe 50 may be operated simultaneously or in parallel to open the first branch pipe section 50B1 and close the second branch pipe section 50B2. Alternatively, the second branch pipe section 50B2 may be closed by the second shutter 62 of the open / close type branch pipe 50, and then the first branch pipe section 50B1 may be opened by the first shutter 60 of the open / close type branch pipe 50. In this case, it is desirable to quickly open the first branch pipe section 50B1 by the first shutter 60 of the open / close type branch pipe 50 so as not to require the concrete pump or the like to be stopped.

[0061] (Parallel pouring process) Next, the parallel pouring step will be described. In the parallel pouring step, as shown in Fig. 5, with the lower end of the second tremie pipe 30 positioned higher than the lower end of the first tremie pipe 20, the second branch pipe section 50B2 is opened by the second shutter 62 of the open / close branch piping 50, thereby supplying concrete from the concrete supply pipe 52 to the second tremie pipe 30. As a result, concrete is supplied from the concrete supply pipe 52 to the second tremie pipe 30, and the concrete is poured into the pile hole 10 via the second tremie pipe 30.

[0062] At this time, the first shutter 60 keeps the first branch pipe section 50B1 open. As a result, concrete is supplied from the concrete supply pipe 52 to the first tremie pipe 20, and concrete is continuously poured into the pile hole 10 via the first tremie pipe 20. In other words, concrete is poured into the pile hole 10 from the concrete supply pipe 52 via the first tremie pipe 20 and the second tremie pipe 30.

[0063] As a result, in this embodiment, compared to when concrete is poured into the pile hole 10 from either the first tremie pipe 20 or the second tremie pipe 30, the bias of the poured concrete 16 poured into the pile hole 10 is suppressed, and the filling ability of the poured concrete 16 into the gaps in the reinforcing bar cage 14 is improved.

[0064] (First tremie tube pulling process) Next, the first tremie pipe pulling-up step will be described. As shown in Figure 6, in the first tremie pipe pulling-up step, as described above, the first tremie pipe 20 is pulled up and the upper end side of the first tremie pipe 20 is severed at the connecting part J of the piping 42 while pouring concrete into the pile hole 10 using the second tremie pipe 30 so that the insertion length L of the lower ends of the first tremie pipe 20 and second tremie pipe 30 into the poured concrete 16 is not less than a lower limit value and not more than an upper limit value.

[0065] As a result, the lower end of the first tremie tube 20 is positioned higher than the lower end of the second tremie tube 30. The amount by which the first tremie tube 20 is pulled up is set to be approximately the same as the amount by which the second tremie tube 30 is pulled up.

[0066] In this manner, in this embodiment, the first tremie pipe 20 is pulled up and the upper end side of the first tremie pipe 20 is severed at the connection part J of the piping 42 without interrupting the pouring of concrete into the pile hole 10.

[0067] The above procedure is repeated as appropriate, and the first tremie pipe 20 and the second tremie pipe 30 are alternately pulled up while concrete is continuously poured into the pile hole 10. In this way, a cast-in-place concrete pile is constructed.

[0068] (action) Next, the operation of this embodiment will be described.

[0069] According to the construction method for a cast-in-place concrete pile of this embodiment, as described above, concrete is poured into the pile hole 10 via the first tremie pipe 20 and the second tremie pipe 30 in the parallel pouring process.

[0070] As a result, in this embodiment, compared to when concrete is poured into the pile hole 10 through either the first tremie pipe 20 or the second tremie pipe 30, it is possible to suppress unevenness in the poured concrete 16 poured into the pile hole 10, and it is also possible to improve, for example, the filling ability of the concrete into the gaps in the reinforcing bar cage 14.

[0071] In addition, in the first tremie pipe pulling-up process, the supply of concrete to the first tremie pipe 20 is stopped, and while concrete is poured into the pile hole 10 through the second tremie pipe 30, the first tremie pipe 20 is pulled up and the upper end side of the first tremie pipe 20 is severed at the connection part J of the piping 40, 42.

[0072] Next, in the second tremie pipe pulling-up process, the supply of concrete to the second tremie pipe 30 is stopped, and while concrete is poured into the pile hole 10 through the first tremie pipe 20, the second tremie pipe 30 is pulled up and the upper end side of the second tremie pipe 30 is severed at the connection part J of the piping 40, 42.

[0073] In this way, in this embodiment, the first tremie pipe 20 and the second tremie pipe 30 are pulled up in order and their upper ends are severed without interrupting the pouring of concrete into the pile hole 10. As a result, in this embodiment, the construction time can be shortened compared to when pouring of concrete into the pile hole 10 is interrupted every time the tremie pipes are pulled up and their upper ends are severed. Therefore, deterioration of concrete properties such as slump can be suppressed.

[0074] Furthermore, in this embodiment, in the first tremie pipe pulling up step, the supply of concrete to the first tremie pipe 20 is stopped by closing the first tremie pipe 20 side of the open / close type branch piping 50, i.e., the first branch pipe section 50B1 with the first shutter 60. Furthermore, in the second tremie pipe pulling up step, the supply of concrete to the second tremie pipe 30 is stopped by closing the second tremie pipe 30 side of the open / close type branch piping 50, i.e., the second branch pipe section 50B2 with the second shutter 62.

[0075] In this way, in this embodiment, by operating the first shutter 60 and the second shutter 62 of the open / close branch pipe 50, the tremie pipe for pouring concrete can be easily switched between the first tremie pipe 20 and the second tremie pipe 30.

[0076] Furthermore, in this embodiment, the upper ends of the first tremie pipe 20 and the second tremie pipe 30 are separated at the connecting portion J of the piping 40, 42. This makes it possible to easily separate the upper ends of the first tremie pipe 20 and the second tremie pipe 30, thereby improving workability.

[0077] Furthermore, the first tremie pipe 20 and the second tremie pipe 30 have a portion where the connecting portion J of the piping 40, 42 is misaligned in the axial direction when one end (lower end) of each pipe is aligned. This makes it possible to change the amount of lifting of the first tremie pipe 20 and the second tremie pipe 30 while separating the upper end sides of the first tremie pipe 20 and the second tremie pipe 30 at the connecting portion J of the piping 40, 42. This further improves workability.

[0078] (Variation) Next, a modification of the above embodiment will be described.

[0079] The order of the parallel concrete pouring step, the first tremie pipe pulling up step, and the second tremie pipe pulling up step in the above embodiment can be changed as appropriate. Furthermore, the parallel concrete pouring step may be performed as needed and can be omitted as appropriate.

[0080] Furthermore, in the above embodiment, the tremie pipe into which concrete is poured is switched between the first tremie pipe 20 and the second tremie pipe 30 by the first shutter 60 and the second shutter 62 of the open / close type branch pipe 50. However, the switching of the tremie pipe into which concrete is poured is not limited to the first shutter 60 and the second shutter 62, and may also be done by, for example, a switching valve that switches between the first branch pipe section 50B1 and the second branch pipe section 50B2. Furthermore, the structure of the open / close type branch pipe 50 can be modified as appropriate.

[0081] Furthermore, in the above embodiment, the first tremie pipe 20 and the second tremie pipe 30 are connected to pipes 40, 42 with different axial lengths. However, the first tremie pipe 20 and the second tremie pipe 30 may be connected to a plurality of pipes with the same axial length. In this case, it is preferable to shorten the axial length of the pipes and increase the number of pipe connections. This is because, for example, it becomes possible to select a connection portion that separates the upper end sides of the first tremie pipe 20 and the second tremie pipe 30 from the plurality of pipe connection portions depending on the rising speed of the poured concrete 16 in the pile hole 10, etc.

[0082] Furthermore, in the above embodiment, the upper end sides of the first tremie pipe 20 and the second tremie pipe 30 are separated at the connecting part J of the pipes 40, 42. However, the upper end sides of the first tremie pipe 20 and the second tremie pipe 30 are not limited to being separated at the connecting part J of the pipes 40, 42, and it is also possible to separate them by cutting them midway through the pipes 40 or 42, for example.

[0083] In the above embodiment, concrete is poured into the pile hole 10 using two tremie pipes, the first tremie pipe 20 and the second tremie pipe 30. However, concrete may be poured into the pile hole 10 using three or more tremie pipes. In this case, for example, the supply of concrete to some of the tremie pipes is stopped, and concrete is poured into the pile hole 10 using the other tremie pipes, while some of the tremie pipes are pulled up and their upper ends are cut off.

[0084] Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and one embodiment and various modified examples may be used in appropriate combination, and it goes without saying that the present invention can be implemented in various forms as long as it does not deviate from the gist of the present invention. [Explanation of symbols]

[0085] 10 Pileholes 16 Cast concrete (concrete) 20 First tremie tube 30 Second tremie tube 40 Piping 42 Piping J Pipe connection 50 Openable branch piping G Ground

Claims

1. A method for constructing a cast-in-place concrete pile in which concrete is poured into a pile hole using a first tremie pipe and a second tremie pipe inserted into the pile hole, a first tremie pipe pulling-up process in which the supply of concrete to the first tremie pipe is stopped, and concrete is poured into the pile hole through the second tremie pipe while the first tremie pipe is pulled up and an upper end side of the first tremie pipe is severed; a second tremie pipe pulling-up process in which the supply of concrete to the second tremie pipe is stopped, and the second tremie pipe is pulled up to cut off an upper end side of the second tremie pipe while pouring concrete into the pile hole through the first tremie pipe; A method for constructing cast-in-place concrete piles comprising:

2. the first tremie pipe and the second tremie pipe are connected to a concrete supply pipe via an open / close branch pipe; in the first tremie pipe pulling-up step, the supply of concrete to the first tremie pipe is stopped by closing the first tremie pipe side of the open / close type branch pipe, In the second tremie pipe pulling-up step, the second tremie pipe side of the open / close type branch pipe is closed to stop the supply of concrete to the second tremie pipe. A method for constructing a cast-in-place concrete pile according to claim 1.

3. A parallel pouring step of pouring concrete into the pile hole using the first tremie pipe and the second tremie pipe is provided. A method for constructing a cast-in-place concrete pile according to claim 1 or 2.

4. A method for constructing a cast-in-place concrete pile in which concrete is poured into a pile hole using a first tremie pipe and a second tremie pipe inserted into the pile hole, the first tremie pipe and the second tremie pipe each have a plurality of pipes that are axially separably connected, the first tremie pipe and the second tremie pipe have a portion where a connecting portion of the pipe is shifted in the axial direction when one ends of the first tremie pipe and the second tremie pipe are aligned with each other, a first tremie pipe pulling-up process in which the supply of concrete to the first tremie pipe is stopped, and concrete is poured into the pile hole through the second tremie pipe while the first tremie pipe is pulled up and the upper end side of the first tremie pipe is severed at the connecting portion of the piping; a second tremie pipe pulling-up process in which the supply of concrete to the second tremie pipe is stopped, and while pouring concrete into the pile hole through the first tremie pipe, the second tremie pipe is pulled up and the upper end side of the second tremie pipe is severed at the connecting portion of the piping; A method for constructing cast-in-place concrete piles comprising:

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