First tube

Abstract

To provide a casing tube which can improve the possibility of forming a pile having a designed diameter regardless of fluidity of concrete, to ensure a covering thickness of a reinforcing cage, and to ensure soundness of a reinforced concrete pile in an all-casing construction method.SOLUTION: A first tube (2) comprises a tube main body (21) and a drilling bit (22). The tube main body (21) has a predetermined thickness (m) that is not zero. An inner diameter (21b) of the tube main body (21) is smaller than a design diameter (K) of a pile to be constructed, and is such that a distance (L) from an inner surface (21d) of the tube main body (21) to the design diameter (K) is less than 55 mm. An outer diameter (21a) of the tube main body (21) is smaller than the design diameter (K) and is such that a distance from an outer surface (21c) of the tube main body (21) to the design diameter (K) is less than 10 mm, or is equal to or greater than the design diameter (K).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a first tube used in the all-casing construction method. [Background technology]

[0002] The all-casing method is a conventional method for forming cast-in-place reinforced concrete piles. In this all-casing method, multiple intermediate casing tubes are connected to a first tube equipped with multiple drilling bits at its lower end, and a pile hole is formed by rotating and pressing the tubes in using a full-rotation rotary machine. After erecting a reinforcing bar cage in the pile hole, the casing tubes are pulled out while concrete is poured using a tremie pipe. This completes the formation of a reinforced concrete pile.

[0003] However, with this all-casing method, it is known that the diameter of the reinforced concrete pile formed does not always match the designed diameter. Furthermore, if the pile diameter does not reach the designed value, the thickness of the reinforcing cage and concrete cover will not be as designed. There are several causes for this problem. For example, when the casing tube is pulled out, the ground moves toward the pile hole. Another factor is that the poor fluidity of concrete prevents the pile from expanding sufficiently to the designed diameter even when the casing tube is pulled out.

[0004] In this regard, for example, a technology such as that described in Patent Document 1 is known. The technology described in Patent Document 1 improves the soil near the ground where the lateral pressure of the concrete is particularly lower than the earth pressure of the surrounding ground, so that the ground does not move toward the pile hole even when the casing tube is pulled out. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-014000 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the technology described in Reference 1, if the fluidity of the concrete is poor, the pile diameter will not be as designed, and therefore the covering thickness of the reinforcing bar cage will not be as designed.

[0007] In view of the above problems, the present invention aims to provide a casing tube that improves the possibility of forming piles with the designed diameter regardless of the fluidity of the concrete, thereby ensuring the covering thickness of the reinforcing bar cage and thereby ensuring the soundness of reinforced concrete piles using the all-casing construction method. [Means for solving the problem]

[0008] The above object of the present invention can be achieved by the following means: Note that the parentheses indicate reference symbols of embodiments to be described later, but the present invention is not limited to these.

[0009] The first tube (2) according to claim 1 is A first tube (2) used in the all-casing construction method, The first tube (2) includes a tube body (21) and a drilling bit (22), The tube body (21) has a predetermined thickness (m) that is not 0, The inner diameter (21b) of the tube body (21) is shorter than the design diameter (K) of the pile to be constructed, and the distance (L) from the inner surface (21d) of the tube body (21) to the design diameter (K) is less than 55 mm, The outer diameter (21a) of the tube body (21) is shorter than the design diameter (K) and has a length such that the distance from the outer surface (21c) of the tube body (21) to the design diameter (K) is less than 10 mm, or the length is equal to or greater than the design diameter (K), The drilling bit (22) is characterized in that it is arranged on the drilling tip side of the tube body (21) so that the cutting edge outer diameter is larger than the design diameter (K).

[0010] The first tube (2) according to claim 2 is the first tube (2) according to claim 1, The first tube (2) further includes a joint (a conventional joint Jj), The joint (conventional joint Jj) is characterized in that it connects an intermediate casing tube (Jm) having a tube body portion with an outer diameter (Ja) shorter than the outer diameter (21a) of the tube body portion (21).

[0011] The first tube (2) according to claim 3 is the first tube (2) according to claim 1, The first tube (2) further comprises a joint (4), The joint (4) is characterized in that it connects an intermediate casing tube (3) having a tube body portion with an outer diameter (31a) having the same length as the outer diameter (21a) of the tube body portion (21).

[0012] The intermediate casing tube (3) recited in claim 4 is characterized in that it is an intermediate casing tube (3) connected to the first tube (2) recited in claim 3. [Effects of the Invention]

[0013] Next, the effects of the present invention will be described with reference to the drawings. Note that the reference symbols in parentheses are those of the embodiments described below, but the present invention is not limited to these.

[0014] According to the invention of claim 1, the inner diameter (21b) is set so that the distance from the inner surface (21d) of the tube body (21) to the design diameter (K) of the pile to be constructed (see distance L in Fig. 2(b)) is shorter than the conventional industry standard of 55 mm (see Figs. 1(b), 2(b), and 4(a)). Therefore, when the casing tube (1) is pulled out, the concrete inside the casing tube (1) flows only a shorter distance (L) before reaching the design diameter (K). Therefore, even if the fluidity of the concrete is low, there is a high possibility that a pile with the designed diameter (K) can be formed.

[0015] In addition, the inner diameter (21b) of the tube body (21) is shorter than the design diameter (K) of the pile to be constructed (see Figure 2(b)). This eliminates the risk that the concrete will already have spread over an area larger than the design diameter (K) of the pile to be constructed before the casing tube (1) is pulled out, preventing the pile from being formed with the designed diameter (K).

[0016] Furthermore, the outer diameter (21a) of the tube body (21) is longer than the conventional industry standard, and the drilling bit (22) is positioned so that the cutting edge outer diameter is larger than the design diameter (K). This means that there is no need to thin the thickness (m) of the tube body (21) when shortening the distance from the inner surface (21d) of the tube body (21) to the design diameter (K) of the pile to be constructed (see distance L in Figure 2(b)) below the conventional industry standard of 55 mm (see Figures 2(b) and 4(a)). This allows for maintaining strength.

[0017] Therefore, according to the present invention, the possibility of forming a pile with the designed pile diameter (K) is improved regardless of the fluidity of the concrete, thereby ensuring the covering thickness of the reinforcing bar cage, thereby ensuring the soundness of reinforced concrete piles using the all-casing construction method.

[0018] According to the invention of claim 2, the joint (Jj) provided on the first tube (2) further connects an intermediate casing tube (Jm) having a diameter smaller than the outer diameter (21a) of the tube body (21) of the first tube (2) (see FIG. 2(a)). This makes it possible to use a conventional intermediate casing tube (Jm) having a shorter outer diameter (21a) than the first tube (2). Therefore, there is no need to newly manufacture an intermediate casing tube (3) having a diameter equal to the outer diameter (21a) of the tube body (21) of the first tube (2), thereby reducing costs.

[0019] According to the invention of claim 3, the joint 4 provided on the first tube 2 connects to the intermediate casing tube 3 having a diameter 31a equal to the outer diameter 21a of the tube body 21 of the first tube 2 (see FIG. 3(a)). This allows the first tube 2 and the intermediate casing tube 3 to be connected flush. Therefore, when the casing tube 1A is pulled out, it is less likely to get caught on the surrounding ground, making it easier to pull out.

[0020] According to the invention of claim 4, the intermediate casing tube (3) has a diameter (31a) that is the same as the outer diameter (21a) of the tube main body (21) of the first tube (2), so it can be connected flush with the first tube (2). [Brief explanation of the drawings]

[0021] [Figure 1] 1(a) is a front view of a casing tube in which a conventional first tube and a conventional intermediate casing tube are connected, and FIG. 1(b) is an enlarged view of the lower right portion of the first tube shown in FIG. [Figure 2] 1A is a front view of a casing tube in which a first tube according to one embodiment of the present invention is connected to a conventional intermediate casing tube, and FIG. 1B is an enlarged view of the lower right portion of the first tube shown in FIG. 1A. [Figure 3]FIG. 10 is a front view of a casing tube in which a first tube according to one embodiment of the present invention and an intermediate casing tube according to a modified example are connected. [Figure 4] (a) is a table showing the specifications of a first tube and a conventional intermediate casing tube according to conventional industry standards, and (b) and (c) are tables showing the specifications of a first tube and an intermediate casing tube according to one embodiment of the present invention. The unit is "mm." DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of a casing tube according to the present invention will be described in detail with reference to the drawings. In the following description, when directions such as up, down, left, and right are indicated, they refer to up, down, left, and right when viewed from the front of the illustration.

[0023] <Outline of the casing tube> First, a conventional intermediate casing tube Jm and a conventional first tube Jf will be described with reference to Fig. 1. Next, a first tube 2 according to this embodiment to which the conventional intermediate casing tube Jm (see Fig. 1(a)) is connected will be described with reference to Fig. 2.

[0024] <Explanation of conventional casing tube> As shown in FIG. 1(a), both the conventional intermediate casing tube Jm and the first tube Jf include a tube body J1 with an outer diameter Ja and an inner diameter Jb. According to the conventional industry standard (see FIG. 4(a)), this tube body J1 has a thickness of 45 mm as shown in FIG. 1(b) (the difference between the outer diameter Ja and the inner diameter Jb shown in FIG. 4(a) / 2). Furthermore, a plurality of drilling bits Je are provided on the drilling tip side of the first tube Jf (below the tube body J1 shown in FIG. 1). According to the industry standard, these drilling bits Je are arranged to protrude by a length of 10 mm (the difference between the outer diameter Ja and the outer cutting edge dimension shown in FIG. 4(a) / 2) from the outer surface Jc of the tube body J1, as shown in FIG. 1(b).

[0025] The inner diameter Jb of the tube body J1 shown in Figure 1(a) is determined by subtracting 55 mm from the design diameter K of the pile to be constructed. This 55 mm is the sum of the thickness of the tube body J1 (45 mm) (see Figure 1(b)) and the length of the drill bit extending from the outer surface Jc (10 mm) (see Figure 1(b)). Therefore, according to industry standards, if the design diameter K of the pile to be constructed is 1000 mm, the inner diameter Jb is 890 mm (1000 mm - 55 mm * 2) (see Figure 4(a)). Similarly, if the design diameter K of the pile to be constructed is 1500 mm, the inner diameter Jb is 1390 mm, and if the design diameter K of the pile to be constructed is 2000 mm, the inner diameter Jb is 1890 mm (see Figure 4(a)).

[0026] The outer diameter Ja of the tube body J1 shown in Figure 1(a) is determined by subtracting 10 mm from the design diameter K of the pile to be constructed. The reason for subtracting 10 mm is to ensure that the drill bit Je overhangs 10 mm (see Figure 1(b)) between the outer surface Jc (see Figure 1(a)) and the design diameter K of the pile to be constructed (see Figure 1(b)). Therefore, according to industry standards, if the design diameter K of the pile to be constructed is 1000 mm, the outer diameter Ja is 980 mm (1000 mm - 10 mm * 2) (see Figure 4(a)). Similarly, if the design diameter K of the pile to be constructed is 1500 mm, the outer diameter Ja is 1480 mm, and if the design diameter K of the pile to be constructed is 2000 mm, the outer diameter Ja is 1980 mm (see Figure 4(a)).

[0027] Furthermore, in the conventional first tube Jf shown in Figure 1(a), the drilling bit Je (see Figure 1(b)) is attached to the entire circumference of the cutting tip side so that it protrudes by 10 mm from the outer surface Jc (see Figure 1(a)) of the tube body J1 (see Figure 1(b)). Therefore, the cutting edge outer diameter (cutter diameter) of the conventional first tube Jf is equal to the design diameter K of the pile to be constructed (see Figure 4(a)). As a result, the conventional intermediate casing tube Jm and the conventional first tube Jf, which are manufactured based on the industry standard shown in Figure 4(a), can excavate a pile hole with the design diameter K of the pile to be constructed.

[0028] In the all-casing method, concrete is poured into the casing tube J shown in Figure 1(a) using a tremie pipe. When the casing tube J is pulled out, the poured concrete flows a predetermined distance from the inner surface Jd (see Figure 1(b)) of the tube body J1 (see Figure 1(a)) to the design diameter K (see Figure 1(b)). This flow distance is obtained by dividing the difference between the design diameter K and the inner diameter Jb of the pile to be constructed by 2. Therefore, according to conventional industry standards, this distance is 55 mm (see Figure 1(b) and Figure 4(a)).

[0029] <First Tube Explanation> Next, the first tube 2 according to this embodiment will be described. Here, the first tube 2 will be described when the design diameter K of the pile to be constructed is 1000 mm. As shown in FIG. 2(a), the first tube 2 comprises a tube main body 21, a drilling bit 22, and a conventional joint Jj. The first tube 2 is connected to a conventional intermediate casing tube Jm via the conventional joint Jj. This conventional intermediate casing tube Jm is the same as that shown in FIG. 1, and therefore its description will be omitted.

[0030] <Explanation of the tube body and drilling bit> The tube main body 21 shown in FIG. 2(a) has a predetermined thickness m, as shown in FIG. 2(a). This thickness m may be 45 mm, which is the same as the conventional industry standard. Furthermore, as shown in FIG. 2(a), a plurality of drilling bits 22 are provided on the drilling tip side of the tube main body 21 (the lower side of the tube main body 21 shown in FIG. 2(a)). As shown in FIG. 2(b), these drilling bits 22 are provided so as to protrude a predetermined length from the outer surface 21c of the tube main body 21. This length may be 10 mm, which is the same as the conventional industry standard.

[0031] Next, the inner diameter 21b of the tube main body 21 shown in FIG. 2(a) is set to be shorter than the design diameter K of the pile to be installed, and the distance L (see FIG. 2(b)) from the inner surface 21d of the tube main body 21 to the design diameter K is set to be less than 55 mm. More specifically, the inner diameter 21b (see FIG. 2(a)) is set to be longer than the inner diameter Jb of the conventional first tube Jf (see the inner diameter Jb in FIG. 1(a) and the inner diameter Jb in FIG. 2(a)). As a result, as shown in FIG. 2(b), the inner surface 21d is closer to the design diameter K than the inner surface Jd of the conventional first tube Jf (shown by the two-dot chain line in FIG. 2(b)). As a result, the distance L from the inner surface 21d of the tube main body 21 to the design diameter K of the pile to be installed becomes shorter by a length LS (see FIG. 2(b)) than the conventional 55 mm (see FIG. 2(b)).

[0032] An example of a method for setting the inner diameter 21b is as follows. For example, as shown in FIG. 4(b), the inner diameter 21b may be set to 900 mm, which is 10 mm longer than the industry standard of 890 mm (see FIG. 4(a)). In this case, the difference between the design diameter K of the pile to be installed and the inner diameter Jb is 100 mm, and the distance L (see FIG. 2(b)) from the inner surface 21d to the design diameter K is 50 mm, which is 100 mm divided by 2. Therefore, the distance L (see FIG. 2(b)) from the inner surface 21d to the design diameter K is 5 mm (see length LS in FIG. 2(b)) shorter than the industry standard distance of 55 mm (see FIG. 2(b)).

[0033] Similarly, as shown in Figure 4(b), if the inner diameter 21b is set to "910 mm", which is 20 mm longer, the distance L (see Figure 2(b)) will be 10 mm shorter, that is, 45 mm; if the inner diameter 21b is set to "920 mm", which is 30 mm longer, the distance L (see Figure 2(b)) will be 15 mm shorter, that is, 40 mm; and if the inner diameter 21b is set to "930 mm", which is 40 mm longer, the distance L (see Figure 2(b)) will be 20 mm shorter, that is, 35 mm. In this way, if the inner diameter 21b (see Figure 2(a)) is set to be longer than the inner diameter Jb of the conventional first tube Jf (see inner diameter Jb in Figure 1(a) and inner diameter Jb in Figure 2(a)), the distance L (see Figure 2(b)) from the inner surface 21d to the designed diameter K will be shorter by a length LS (see Figure 2(b)) than the conventional 55 mm (see Figure 2(b)).

[0034] In this way, the inner diameter 21b is set (see FIG. 2(b)) so that the distance L (see FIG. 2(b)) from the inner surface 21d of the tube body 21 of the first tube 2 (see FIG. 2(a)) to the design diameter K of the pile to be constructed is shorter than the conventional industry standard of 55 mm. Therefore, when the casing tube 1 (see FIG. 2(a)) is pulled out, the concrete trapped inside the first tube 2 only needs to flow the shorter distance L (see FIG. 2(b)) to reach the design diameter K (see FIG. 2(b)). Therefore, even if the fluidity of the concrete is low, there is a high possibility that a pile with the designed diameter K can be formed.

[0035] The length of the inner diameter 21b (see FIG. 2(a)) is not limited to the example shown in FIG. 4(b). If the inner diameter 21b (see FIG. 2(a)) is set longer than the conventional industry standard, the distance L (see FIG. 2(b)) from the inner surface 21d to the design diameter K will be shorter by that amount, LS, than the conventional 55 mm (see FIG. 2(b)). Therefore, when the casing tube 1 is pulled out, the concrete in the first tube 2 will reach the design diameter K (see FIG. 2(b)) by flowing only the shorter distance L (see FIG. 2(b)).

[0036] 2(b), the inner diameter 21b of the tube main body 21 is shorter than the designed diameter K of the pile to be constructed. This eliminates the risk that the concrete will already have spread over an area larger than the designed diameter K of the pile to be constructed before the casing tube 1 (see FIG. 2(a)) is pulled out, preventing the pile from being formed with the designed diameter K.

[0037] In this embodiment, the inner diameter 21b of the tube main body 21 is made longer than the conventional industry standard, and accordingly, the outer diameter 21a (see FIG. 2(a)) is also made longer than the conventional industry standard. An example of a method for setting such outer diameter 21a is as follows. For example, as shown in FIG. 4(b), if the inner diameter 21b is set to "900 mm", which is 10 mm longer than the industry standard of 890 mm (see FIG. 4(a)), the outer diameter 21a can also be set to "990 mm", which is 10 mm longer than the industry standard (see FIG. 4(a)). Similarly, if the inner diameter 21b is set to 910 mm, which is 20 mm longer, the outer diameter 21a can also be set to 1000 mm, which is 20 mm longer; if the inner diameter 21b is set to 920 mm, which is 30 mm longer, the outer diameter 21a can also be set to 1010 mm, which is 30 mm longer; and if the inner diameter 21b is set to 930 mm, which is 40 mm longer, the outer diameter 21a can also be set to 1040 mm, which is 40 mm longer (see Figure 4(b)).

[0038] Furthermore, by making the outer diameter 21a longer than the conventional industry standard, it is not possible to ensure the length (see "10 mm" in Figure 1(a)) that the drilling bit 22 overhangs between the outer surface 21c of the tube main body 21 and the design diameter K of the pile to be constructed. Therefore, the drilling bit 22 is positioned so that the cutting edge outer diameter is larger than the design diameter K (see Figures 2(b) and 4(b)).

[0039] In this way, the outer diameter 21a (see FIG. 2(a)) is set and the drilling bit 22 (see FIG. 2(a)) is positioned. As a result, when setting the inner diameter 21b so that the distance L (see FIG. 2(b)) from the inner surface 21d of the tube main body 21 to the design diameter K of the pile to be constructed is shorter than the conventional industry standard of 55 mm, there is no need to thin the thickness m (see FIG. 2(a)) of the tube main body 21. Therefore, strength can be maintained.

[0040] Note that the outer diameter 21a (see FIG. 2(a)) need not necessarily be longer by the same amount as the inner diameter 21b (see FIG. 2(a)) being longer than the inner diameter Jb (see FIG. 1(a)). In other words, the outer diameter 21a (see FIG. 2(a)) may be longer than the outer diameter Ja (see FIG. 1(a)). Conventionally, the outer diameter Ja is determined by subtracting 10 mm from the design diameter K of the pile to be constructed (see FIG. 1(b)). Therefore, to make the outer diameter 21a (see FIG. 2(a)) longer than the outer diameter Ja (see FIG. 1(a)), the outer diameter 21a (see FIG. 2(a)) may be set to a length shorter than the design diameter K of the pile to be constructed so that the distance to the design diameter K is less than 10 mm, or to a length equal to or greater than the design diameter K of the pile to be constructed. Even in this case, there is no need to reduce the thickness m (see FIG. 2(a)) of the tube main body 21, thereby maintaining its strength.

[0041] As shown in Figure 2(b), the outer diameter of the cutting edge of the first tube 2 is larger than the design diameter K (see also Figure 4(b)). Therefore, as shown in Figure 2(b), the borehole excavated by the first tube 2 is larger than the design diameter K by a distance S (see Figure 2(b)). However, when the casing tube 1 (see Figure 2(a)) is pulled out, the ground around the borehole moves toward the concrete (pile) due to earth pressure, so the distance S (see Figure 2(b)) is filled up.

[0042] The shapes and manufacturing methods of the tube body 21 and the drilling bit 22 are well known and therefore will not be described here.

[0043] <Joint explanation> As shown in FIG. 2(a), a conventional joint Jj is provided at the upper end 23 of the tube main body 21 on the side opposite to the excavation tip side (the upper side of the tube main body 21 shown in FIG. 2(a)).

[0044] As shown in Figure 2(a), this conventional joint Jj has the same outer diameter Ja as the conventional intermediate casing tube Jm, and is compatible in size with the conventional intermediate casing tube Jm. This allows the conventional intermediate casing tube Jm to be connected to the first tube 2. Therefore, there is no need to manufacture a new intermediate casing tube, which reduces costs.

[0045] As shown in FIG. 2(a), the upper end 23 of the tube body 21 of the first tube 2 is tapered to reduce its diameter to the same outer diameter Ja as the conventional joint Jj, and the conventional joint Jj is attached to it.

[0046] However, any joint that can connect a conventional intermediate casing tube Jm need not be the conventional joint Jj. Furthermore, when providing such a joint or a conventional joint Jj to the first tube 2, it is not necessary to tape the upper end 23, and it may be provided by any suitable method.

[0047] The shape and manufacturing method of this conventional joint Jj are well known and therefore will not be described here.

[0048] According to the present embodiment described above, the inner diameter 21b (see FIG. 2(b)) is set so that the distance L (see FIG. 2(b)) from the inner surface 21d of the tube main body 21 to the design diameter K of the pile to be constructed is shorter than the conventional industry standard of 55 mm (see FIGS. 2(b) and 4(a)). Therefore, when the casing tube 1 (see FIG. 2(a)) is pulled out, the concrete in the first tube 2 (see FIG. 2(a)) only needs to flow the shorter distance L (see FIG. 2(b)) to reach the design diameter K. Therefore, even if the fluidity of the concrete is low, it is more likely that a pile with the designed diameter K can be formed.

[0049] Furthermore, according to this embodiment, the inner diameter 21b of the first tube 2 is shorter than the design diameter K of the pile to be constructed (see FIG. 2(b)). This eliminates the risk that the pile cannot be formed as designed because the concrete has already spread over an area larger than the design diameter K of the pile to be constructed before the casing tube 1 (see FIG. 2(a)) is pulled out.

[0050] Furthermore, the outer diameter 21a of the tube body 21 is also made longer than the conventional industry standard, and the drilling bit 22 is positioned so that the cutting edge outer diameter is larger than the design diameter K. As a result, there is no need to thin the thickness m of the tube body 21 when setting the inner diameter 21b so that the distance L (see Figure 2(b)) from the inner surface 21d of the tube body 21 to the design diameter K of the pile to be constructed is shorter than the conventional industry standard of 55 mm. Therefore, strength can be maintained.

[0051] As described above, according to this embodiment, regardless of the fluidity of the concrete, the possibility of forming a pile with the pile diameter K as designed is improved, and therefore the covering thickness of the reinforcing bar cage is ensured, thereby ensuring the soundness of reinforced concrete piles using the all-casing construction method.

[0052] <Description of Modifications> The first tube shown in this embodiment is merely an example, and various modifications and alterations are possible within the scope of the gist of the present invention as described in the claims. For example, in this embodiment, as shown in FIG. 2(a), a conventional intermediate casing tube Jm is connected to the first tube 2, but this is not limited to this. For example, as shown in FIG. 3, an intermediate casing tube 3 having a tube main body 31 with an outer diameter 31a identical to the outer diameter 21a of the first tube 2 may be newly manufactured and connected to the first tube 2 using a joint 4 having an outer diameter 4a identical to the outer diameter 21a. By using such an intermediate casing tube 3, the first tube 2 and the intermediate casing tube 3 are connected flush with each other, as shown in FIG. 3, and therefore, when the casing tube 1A (see FIG. 3) is pulled out, it is less likely to get caught on the surrounding ground, making it easier to pull out.

[0053] As shown in Fig. 3, the intermediate casing tube 3 has an outer diameter 31a that is the same as the outer diameter 21a of the first tube 2, so that the first tube 2 and the intermediate casing tube 3 are connected flush with each other. Therefore, the intermediate casing tube 3 may have an inner diameter 31b and a thickness m that are different from those of the first tube 2. On the other hand, if the intermediate casing tube 3 is made of steel with the same thickness m as the first tube 2, the inner diameter 31b and the outer diameter 31a may be set as shown in Fig. 4(b). In addition, the modified examples of the first tube 2 in this embodiment described below can also be applied to the intermediate casing tube 3.

[0054] The outer diameter 21a and inner diameter 21b of the first tube 2 in the embodiment can be any length within the scope of the gist of the present invention as described in the claims. For example, the outer diameter Ja and inner diameter Jb (see FIG. 2(a)) of a conventional casing tube may be 30 mm or more longer for the following reasons.

[0055] In other words, the Ministry of Land, Infrastructure, Transport and Tourism stipulates that even if the diameter of a manufactured pile is smaller than the design diameter K of the pile to be constructed, it meets the construction management standards as long as the error is within 30 mm (p. I-27, 3-2-4-5 "Cast-in-place Pile Construction" of "Civil Engineering Construction Management Standards and Specification Values ​​(Draft) March 2024"). On the other hand, based on the inventor's experience, there are almost no piles that do not meet the construction management standards. Therefore, even with conventional concrete with poor fluidity, 40 mm (55 mm - 30 mm / 2) of the 55 mm distance (see Figure 1(b)) from the inner surface Jd (see Figure 1(b)) of the conventional first tube Jf (see Figure 1(a)) to the design diameter K is considered to flow.

[0056] Therefore, the first tube 2 according to the present invention may have an inner diameter 21b (see FIG. 2(a)) that is 30 mm or more longer than the industry standard, such as "920 mm" as shown in FIG. 4(b). In this way, the distance L (see FIG. 2(b)) from the inner surface 21d of the first tube 2 (see FIG. 2(a)) to the design diameter K is 40 mm or less. This distance allows even poorly fluid concrete to flow.

[0057] In this way, if the inner diameter 21b (see Figure 2(a)) is set to "920 mm" or more, it is possible to more reliably improve the possibility of forming a pile with the designed pile diameter K, regardless of the fluidity of the concrete.

[0058] In this embodiment, the first tube 2 used when the design diameter K of the pile to be constructed is 1000 mm has been described. Here, the first tube used when the design diameter K of the pile to be constructed is 1500 mm or 2000 mm will be described. The first tube used when the design diameter K of the pile to be constructed is 1500 mm or 2000 mm has also been conventionally configured using the same thickness (45 mm shown in FIG. 1(b)) and overhang length of the drilling bit 22 (10 mm shown in FIG. 1(b)) as the first tube 2 when the design diameter K of the pile to be constructed is 1000 mm. Therefore, as shown in FIG. 4(a), the distance from the inner surface Jd to the design diameter K of the pile to be constructed is 55 mm. Therefore, if the first tube used when the design diameter K of the pile to be constructed is 1500 mm or 2000 mm has an inner diameter 21b (see Figure 2(a)) longer than the conventional inner diameter Jb of 1390 mm or 1890 mm (see Figure 4(a)), the distance L (see Figure 2(b)) from the inner surface to the design diameter K of the pile to be constructed will be shorter than 55 mm. As an example, as shown in Figure 4(c), when the design diameter K of the pile to be constructed is 1500 mm, the inner diameter 21b and outer diameter 21a can be made 30 mm longer than the inner diameter Jb and outer diameter Ja (see Figure 4(a)), to be 1420 mm and 1510 mm, and the drilling bit 22 can be positioned so that the cutting edge outer diameter is 1530 mm. Furthermore, if the design diameter K of the pile to be constructed is 2000 mm, the inner diameter 21b and outer diameter 21a can be made 30 mm longer than the inner diameter Jb and outer diameter Ja (see Figure 4(a)), to be 1920 mm and 2010 mm, and the drilling bit 22 can be positioned so that the cutting edge outer diameter is 2030 mm. In this way, as shown in Figure 4(c), the distance L (see Figure 2(b)) from the inner surface 21d to the design diameter K of the pile to be constructed is 40 mm, which is 15 mm shorter than the conventional 55 mm (see Figure 2(b)) (see length LS in Figure 2(b)).

[0059] As with the case of 1000 mm, the length of the inner diameter 21b (see FIG. 2(a)) of the first tube used when the design diameter K of the pile to be constructed is 1500 mm or 2000 mm is not limited to the example shown in FIG. 4(c). Furthermore, the design diameter K of the pile to be constructed exemplified in this specification is merely an example. Therefore, the present invention can also be applied to first tubes used to excavate design diameters K of lengths other than these examples, within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0060] 1. 1A casing tube 2. First Tube 21 Tube body 21a Outer diameter 21b Inner diameter 22 Drilling Bit Jm Conventional intermediate casing tube Jj Conventional joint Ja Conventional casing tube outer diameter Jb Inner diameter of conventional casing tube 3 Intermediate casing tube 31 Tube body 31a Outer diameter 31b Inner diameter 4 Joint K Design diameter of the pile to be constructed

Claims

1. A first tube used in the all-casing construction method, The first tube includes a tube body and a drilling bit. the tube body has a predetermined non-zero thickness; The inner diameter of the tube body is shorter than the design diameter of the pile to be constructed, and the distance from the inner surface of the tube body to the design diameter is less than 55 mm, The outer diameter of the tube main body is shorter than the design diameter and has a length such that the distance from the outer surface of the tube main body to the design diameter is less than 10 mm, or the length is equal to or greater than the design diameter, The drilling bit is arranged on the drilling tip side of the tube body so that the cutting edge outer diameter is larger than the design diameter. First tube.

2. The first tube further comprises a joint; The joint connects an intermediate casing tube having a tube body portion with an outer diameter smaller than the outer diameter of the tube body portion. The first tube according to claim 1 .

3. The first tube further comprises a joint; The joint connects an intermediate casing tube having a tube body portion with an outer diameter having the same length as the outer diameter of the tube body portion. The first tube according to claim 1 .

4. An intermediate casing tube connected to the first tube according to claim 3.

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