Central push tube set

Abstract

To surely seal between the inside and the outside of a standard pipe in an inner pushing method.SOLUTION: The center push inner pipe front cylinder part 22 is constituted by connecting a center push inner pipe first cylinder part 22A on the rear side and a center push inner pipe second cylinder part 22B on the front side, and an outer diameter of the center push inner pipe second cylinder part 22B is set smaller than that of the center push inner pipe first cylinder part. Therefore, in FIG. 2, a step is formed on the outer surface of the front cylinder part 22 of the middle push inner tube so that the outer diameter becomes smaller on the front side. A sealing member 26 is mounted on the 22A of the first cylindrical portion of the inner push tube, and a sealing member 27 is mounted on the 22B of the second cylindrical portion of the inner push tube. In a state in which the inner pushing outer tube and the inner pushing inner tube 20 are combined with each other, the sealing member 26 seals between the inner pushing outer tube first cylindrical portion and the inner pushing inner tube first cylindrical portion 22A, and the sealing member 27 seals between the inner pushing outer tube second cylindrical portion and the inner pushing inner tube second cylindrical portion 22B.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to the structure of a center thrust pipe set consisting of two types of center thrust pipes used in combination in the center thrust method used in thrust pipe laying work, and a sealing member that seals the space between them. [Background technology]

[0002] Cylindrical Hume pipes (jacking pipes) made of reinforced concrete or other materials are installed underground, with many of them connected along the central axis. When constructing a structure in which many jacking pipes are connected horizontally from the side of a vertical shaft formed underground, it is necessary to advance the leading jacking pipes forward one after another. This can be done using a jack or other tool, but it is often difficult to install all of the necessary mechanisms within the limited space of the vertical shaft.

[0003] For this reason, a center thrust method is known in which a jack or the like is placed inside a propulsion pipe or the like that has already been installed underground outside the shaft, and this is used to advance the leading propulsion pipe to a predetermined position, after which the used jack or the like is removed and the propulsion pipe further back is connected, and this process is repeated.

[0004] The center thrust method uses a center thrust pipe, which has a different structure from a normal jacking pipe (standard pipe), and applies pressure to the standard pipe indirectly by using a jack. Specifically, jacking pipes are broadly divided into standard pipes, which form the main structure after construction, and center thrust pipes used for jacking work. There are two types of center thrust pipes, as described below. Since the center thrust pipe remains attached to the standard pipe after construction is completed, it is shaped so as not to interfere with the use of the standard pipe. Furthermore, when advancing the jacking pipe as described above, the internal spaces of the standard pipe and the center thrust pipe are sealed from the outside to prevent water or mud from entering the inside of the pipe. Since the center thrust pipe remains as described above even after construction is completed, this sealed state must be maintained permanently. Specific examples of structures for this purpose are described in Patent Documents 1 and 2, for example.

[0005] Figure 5 is a schematic diagram showing the overall configuration of the center thrust method. In the figure, multiple standard pipes 80 are connected and extend from a vertical shaft S formed in the ground G toward the left side of the ground. The structure of the standard pipes 80 is shown in a simplified form. The standard pipes 80 are approximately cylindrical, and each standard pipe 80 is connected along its central axis. Figure 5 shows a cross section along the central axis X. The leading (left) standard pipe 80A has a cutting edge 85 attached to its tip, which can be advanced by applying pressure to the left side of the figure. For this purpose, a center thrust mechanism 90 is installed between the standard pipes 80B and 80C in the figure. The center thrust mechanism 90 is fixed to the rear standard pipe 80C and applies pressure to the front standard pipe 80B, thereby advancing the leading standard pipe 80A underground. Although not shown in Figure 5, a base thrust mechanism is also installed within the vertical shaft S, which pushes the leading standard pipe 80A from the shaft S side.

[0006] Specifically, the center push mechanism 90 is composed of a front center push outer tube (S-shaped tube), a rear center push inner tube (T-shaped tube), and a jack sandwiched between them. When the jack extends or retracts, the center push outer tube and the center push inner tube slide against each other along the central axis X, and this movement advances the front standard tube. Figure 6 is a detailed cross-sectional view of the standard tube 80 in Figure 5, and Figures 7 and 8 are detailed cross-sectional views corresponding to Figure 5, taken along the central axis X, of the center push outer tube 110 and the center push inner tube 120, respectively. Figures 7 and 8 show a state in which an elastic member, described later, is attached.

[0007] In FIG. 6 , a standard pipe 80 includes a standard pipe body 81 made of approximately cylindrical concrete (reinforced concrete) and a metal collar 82 attached to the rear of the body so as to protrude rearward. The outer diameters of the standard pipe body 81 and the collar 82 are set to be equal. The leading end of the standard pipe body 81 is formed as a small-diameter section 81A, which is slightly smaller in diameter so as to fit within the collar 82 of the standard pipe 80 in front of it. This allows standard pipes 80 to be connected using the collar 82 and secured from the inside (toward the central axis X). Although not shown, a sealing member (sealing member) is attached to the small-diameter section 81A to seal the gap between the outer surface of the small-diameter section 81A and the collar 82 of the standard pipe 80 in front of it. This prevents soil and moisture from entering the interior of the standard pipe 80 after it is connected underground.

[0008] In the inner pusher outer tube 110 shown in Figure 7, the rear side (right side in the figure) is provided with a cylindrical inner pusher outer tube rear tubular portion 111 that corresponds to and has the same outer diameter as the collar 82, and the front side is provided with a cylindrical inner pusher outer tube front tubular portion 112 that corresponds to the small diameter portion 81A of the propulsion tube main body 81. Furthermore, the front side (left side in the figure) of the inner pusher outer tube front tubular portion 112 is provided with an inner pusher outer tube front support portion 113 that extends toward the central axis X. When viewed from the front, the inner pusher outer tube front support portion 113 is formed in an annular shape centered on the central axis X. Similarly, the rear side (right side in the figure) is provided with an annular inner pusher outer tube rear support portion 114. The inner pusher outer tube front tubular portion 112 and the inner pusher outer tube rear tubular portion 111 are connected via the inner pusher outer tube rear support portion 114. For this reason, the inner tube rear tubular portion 111, the inner tube front tubular portion 112, the inner tube front support portion 113, and the inner tube rear support portion 114 are integrally formed of metal. In addition, the space between the inner tube front support portion 113 and the inner tube rear support portion 114 is filled with concrete or the like as a filling portion 115.

[0009] Additionally, a sealing member (front sealing member) 116 is attached to the outer surface of the inner tube front cylinder portion 112 of the inner tube 80, as will be described later.

[0010] Similar to the inner pusher outer pipe 110, the inner pusher pipe 120 in Figure 8 is also formed of metal, with an inner pusher pipe rear tubular section 121, an inner pusher pipe front tubular section 122, an inner pusher pipe front support section 123, and an inner pusher pipe rear support section 124 integrated together. In addition, a filling section 125 made of concrete or the like is formed between the inner pusher pipe front support section 123 and the inner pusher pipe rear support section 124.

[0011] As will be described later, a sealing member 126 is attached to the outer surface of the inner tube front tubular portion 122 of the inner pusher tube, sealing the gap between the inner surface of the inner tube rear tubular portion 111 of the inner pusher outer tube 110 at the front. Two sealing members 126 are provided along the direction of the central axis X, and a lubricant injection hole 125A for injecting lubricant from the inside to the outside is formed between them, penetrating the filling section 125 and the inner tube front tubular portion 122 of the inner pusher tube. Note that in Figure 8, all holes except the lubricant injection hole 125A are uniformly provided around the central axis X, but in reality, only the lubricant injection hole 125A is provided in multiple holes dispersed in the circumferential direction.

[0012] Figure 9 shows a specific configuration for actually advancing the standard tube 80 using the above-mentioned inner pusher tube 110 and inner pusher tube 120. Here, only the parts corresponding to the upper parts in Figures 6 to 8 are shown, and the small diameter part 81A of the standard tube 80 is omitted.

[0013] In Figure 9, the structural changes at the above-mentioned points are shown in chronological order from top to bottom. First, as shown in Figure 9(1), the standard tube 80 to be advanced is set in its initial position, and then, as shown in Figure 9(2), the inner tube 110 and the inner tube 120 are inserted and attached from the rear. In reality, the rear standard tube 80 is fixed behind the inner tube 120 with its small diameter portion 81A housed in the inner tube rear cylindrical portion 121, and further behind this, another standard tube 80 is fixed as described above, but these are not relevant to the present invention and are not shown here.

[0014] Here, the inner tube outer support portion 113 of the inner tube outer 110 abuts against the standard tube body 81 of the front standard tube 80, and a jack (pressure tool) 200 and a backing ring 210 are sandwiched between the inner tube outer support portion 114 of the outer tube 110 and the inner tube front support portion 123 of the inner tube inner 120. Here, while a simplified cross section is shown in Figure 9, the backing ring 210 has a circular ring shape similar to the inner tube front support portion 123, and multiple jacks 200 (e.g., 16) are actually provided, evenly distributed in the circumferential direction. The jacks 200 expand and contract in the direction of the central axis X, and are shown in their most contracted state in Figure 9 (2).

[0015] In this state, by fixing the rear end of the rear inner tube 120 and extending the jack 200, the front standard tube 80 (more precisely, the leading standard tube 80A in FIG. 5) can be advanced as shown in FIG. 9(3). After that, by retracting the jack 200 and advancing the inner tube 120 as shown in FIG. 9(4), the entire structure of FIG. 9(2) will be advanced by the amount of extension of the jack 200. After that, the operations of FIG. 9(3) and (4) are repeated again as shown in FIG. 9(5) and (6), and the standard tube 80 can be advanced further. In other words, by repeating the operations of FIG. 9(3) and (4), the standard tube 80 can be advanced to the desired position.

[0016] 9(7), the jack 200 and the backing ring 210 are removed, and the inner tube 120 is advanced as shown in FIG. 9(8), so that the inner tube front support 123 of the inner tube 120 abuts against the outer tube rear support 114 of the outer tube 110. Then, the outer tube 110, the collar 81 of the standard tube 80 in front of it, the inner tube 120, and the outer tube 110 can be fixed by welding or the like. Also, as described above, the rear side of the standard tube 80 is fixed to the inner tube 120, so that the front standard tube 80, the outer tube 110, the inner tube 120, and the rear standard tube 80 are fixed in place.

[0017] Therefore, according to the construction method of Figure 9, the standard pipe 80 can be advanced to a predetermined position underground using the outer pipe 110, the inner pipe 120, the jack 200, etc. Note that Figure 9 only describes advancing the standard pipe 80 at the front end using the outer pipe 110 and the inner pipe 120, but in reality, in the state of Figure 9 (2), the standard pipe 80 connected at the rear end as described above is advanced to a predetermined position via the rear standard pipe 80 using the base pushing mechanism in the vertical shaft S. After that, when it becomes difficult to advance further using the base pushing mechanism, the process from Figure 9 (3) (advancement by jack 200) onwards is carried out. 9 and the advancement by the base push mechanism are actually used in combination, but the issue in the present invention is the matter relating to the change in the relative positional relationship between the leading standard tube 80, the outer center push tube 110, and the inner center push tube 120. Since these relative positions do not change when the base push mechanism is operated, the following will not describe the operation of the base push mechanism. Ultimately, the outer center push tube 110, the inner center push tube 120, etc. can be used as part of a structure in which multiple standard tubes 80 are connected together, together with the standard tubes 80 before and after, without being removed even after construction is completed.

[0018] As described above, during the construction work, sealing member 116 is attached to outer pipe 110, and sealing member 126 is attached to inner pipe 120 to prevent soil and moisture from entering the interior of pipe 80 (the space on the central axis X side). In the state shown in Figure 9, sealing member 116 seals the gap between the outer surface of outer pipe front tubular portion 112 and the inner surface of collar 82 of pipe 80, while sealing member 126 seals the gap between the outer surface of inner pipe front tubular portion 122 and the inner surface of outer pipe rear tubular portion 111 of pipe 110. These sealing members are made of elastic material, and their elastic force seals the gap between the surfaces they abut, preventing soil and moisture from entering. This sealing of the space on the central axis X side by sealing member 116 and sealing member 126 is maintained even after the construction work is completed, as shown in Figure 9 (8). As shown in Figures 7 and 8, these sealing members are attached in advance before the outer and inner tubes 110 and 120 are installed.

[0019] 9, in addition to a force compressing each sealing member in the vertical direction in the figure (direction perpendicular to the central axis X), a force acts in the horizontal direction (direction along the central axis X) when the standard tube 80, the outer inner tube 110, and the inner inner tube 120 move. For this reason, although not shown in the figure, a structure that acts as a stopper to suppress lateral movement of the sealing members is also formed on the surfaces on which these sealing members are attached. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-70479 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-246678 Summary of the Invention [Problem to be solved by the invention]

[0021] In Figure 9, arrows are shown indicating the direction of the force applied to the sealing member in the horizontal direction (along the central axis X) as seen from the sealing member side when performing each step (the relative movement direction of the surface where the sealing member abuts on the upper side). In Figure 9 (2), the outer tube 110 and the inner tube 120 are inserted from the rear (right side), so a force acts on both the sealing member 116 and the sealing member 126 toward the rear (right side), as indicated by arrow A1 and arrow B1, respectively. From Figure 9 (3) onwards, the positional relationship between the outer tube 110 and the standard tube 80 (collar 81) remains unchanged, so no horizontal force is applied to the sealing member 116.

[0022] On the other hand, in (3) of Figure 9, as the jack 200 extends, a force acts on the sealing member 126 toward the front (left) as indicated by arrow B2, and then in (4), a force acts on the sealing member 126 toward the rear (right) as indicated by arrow B3. Figures 9 (5) and (6) are similar to Figures 9 (3) and (4). Furthermore, in (8) of Figure 9, which is the final configuration, a force acts on the sealing member 126 toward the rear (right) as indicated by arrow B4.

[0023] That is, in the above process, a backward force is applied only once to sealing member 116, whereas a backward and forward force is repeatedly applied to sealing member 126. In particular, as described above, the operations (3) and (4) in Figure 9 are repeated multiple times, so this cycle is repeated many times. For this reason, the effect of wear on sealing member 116 is very small, while the effect of wear on sealing member 126 is large, causing durability issues.

[0024] 10(a) and 10(b) are simplified, enlarged cross-sectional views along the front-rear direction showing the sealing member 116, the sealing member 126, and the surrounding structure shown in FIGS. 7 and 8. The stopper structure is omitted here. As described above, a rearward (rightward) force is applied to the sealing member 116 only once. In such a case, as shown in FIG. 10(a), a sealing member 116 made of an elastic material with an asymmetrical configuration can be used, including multiple inclined portions 116A that are inclined rearward and away from the surface to which it is attached (the outer surface of the outer tube front tubular portion 112). This facilitates attachment of the outer tube 110 to the collar 82, as shown in FIG. 9(2), and the elastic force acting on the inclined portions 116A strengthens the seal.

[0025] On the other hand, as mentioned above, because horizontal forces are applied to the sealing member 126 multiple times with alternating directions, the sealing member 126 cannot be formed in the same shape as the sealing member 116. For this reason, the sealing member 126 is formed to have a bilaterally symmetrical shape as shown in FIG. 10(b). Two sealing members 126 are provided in the horizontal direction, and a lubricant injection hole 125A is provided between the two sealing members 126. In particular, in steps (3) and (4) of FIG. 9, a lubricant is injected from the inside of the inner pusher tube 120 to smooth the sliding of the sealing member 126, making it easier to perform the steps of FIG. 9 and suppressing deterioration of the sealing member 126.

[0026] In this case, the sealing member 126 seals the gap between the outer surface of the inner tube inner circumferential portion 122 of the inner tube and the inner surface of the outer tube outer circumferential portion 111 of the outer tube 110 by the elastic force acting on its upper and lower surfaces, but the sealing effect of the sealing member 126 having such a shape is smaller than that of the sealing member 116. Furthermore, as described above, the number of cycles in which force is applied to the sealing member 126 may exceed 1,000 in some cases. In this case, even if the above-mentioned lubricant is used, the sealing member 126 may deteriorate due to wear, and its sealing ability may decrease.

[0027] The gap between the inner tube front tubular portion 122 and the outer tube rear tubular portion 111 must be permanently sealed not only during construction as shown in Figure 9, but also after construction. Therefore, after the configuration shown in Figure 9 (8) was achieved, it became necessary to seal the gap between the inner tube front tubular portion 122 and the outer tube rear tubular portion 111 by welding them in all directions around the central axis X, taking into consideration the deterioration of the sealing member 126 at this point.

[0028] For this reason, there was a demand for technology that could reliably seal the space between the inside and outside of the thrust pipe in the thrust method.

[0029] The present invention has been made in view of the above circumstances, and aims to solve the above problems. [Means for solving the problem]

[0030] The inner pusher tube set of the present invention is used in an inner pusher method for advancing a cylindrical standard pipe having a central axis along the front-to-rear direction underground, and comprises an outer inner pusher tube arranged behind the standard pipe to advance the standard pipe, and an inner inner pusher tube arranged behind the outer inner pusher tube and movable along the central axis relative to the outer inner pusher tube to advance the outer inner pusher tube and the standard pipe, both of which have cylindrical structures coaxial with the standard pipe. The inner inner pusher tube has a front cylindrical portion at the front that is cylindrical and coaxial with the standard pipe, and the outer inner pusher tube has a rear cylindrical portion at the rear that is cylindrical and coaxial with the standard pipe, and the front cylindrical portion of the inner inner pusher tube is movable inside the rear cylindrical portion of the outer inner pusher tube. the front cylindrical portion of the inner tube comprises a first cylindrical portion of the inner tube provided at the rear side and a second cylindrical portion of the inner tube provided at the front side and having an outer diameter smaller than that of the first cylindrical portion of the inner tube; the rear cylindrical portion of the outer tube comprises a first cylindrical portion of the outer tube provided at the rear side and having an inner diameter larger than that of the first cylindrical portion of the inner tube; and a second cylindrical portion of the outer tube provided at the front side and having an inner diameter smaller than that of the first cylindrical portion of the outer tube and larger than that of the second cylindrical portion of the inner tube; and a first sealing member sealing the gap between the outer surface of the first cylindrical portion of the inner tube and the inner surface of the first cylindrical portion of the outer tube; and a second sealing member sealing the gap between the outer surface of the second cylindrical portion of the inner tube and the inner surface of the second cylindrical portion of the outer tube. The center pusher tube set of the present invention is configured to advance the standard tube by pressurizing the center pusher outer tube and the center pusher inner tube using a pressure device installed between the center pusher outer tube and the center pusher inner tube, and the first sealing member is attached to the outer surface of the first tubular portion of the center pusher inner tube, and the second sealing member is attached to the outer surface of the second tubular portion of the center pusher inner tube, and when the standard tube is advanced, the outer surface of the first tubular portion of the center pusher inner tube at the location where the first sealing member is attached and the outer surface of the second tubular portion of the center pusher inner tube at the location where the second sealing member is attached face the inner surface of the first tubular portion of the center pusher outer tube. The inner tube set of the present invention is characterized in that when the outer surface of the first cylindrical portion of the inner tube at the location where the first sealing member is attached and the outer surface of the second cylindrical portion of the inner tube at the location where the second sealing member is attached face the inner surface of the first cylindrical portion of the outer tube, the first sealing member abuts against the inner surface of the first cylindrical portion of the outer tube, and the second sealing member does not abut against the inner surface of the first cylindrical portion of the outer tube. In the center pusher tube set of the present invention, the center pusher outer tube has a center pusher outer tube rear support portion which has a surface extending in a direction perpendicular to the central axis and is pressurized from the rear side, the center pusher outer tube second tubular portion is formed by connecting to the center pusher outer tube rear support portion at the front and the center pusher outer tube first tubular portion at the rear, the center pusher inner tube has a center pusher inner tube front support portion which has a surface extending in a direction perpendicular to the central axis and is pressurized from the front side, the center pusher inner tube second tubular portion is formed by connecting to the center pusher inner tube front support portion at the front and the center pusher inner tube first tubular portion at the rear, and the pressure device is configured to be provided between the center pusher outer tube rear support portion and the center pusher inner tube front support portion. The middle push tube set of the present invention is characterized in that when the middle push outer tube rear support portion of the middle push outer tube and the middle push inner tube front support portion of the middle push inner tube are abutted, the outer surface of the second tubular portion of the middle push inner tube at the point where the second sealing member is attached faces the inner surface of the second tubular portion of the middle push outer tube, and the outer surface of the second tubular portion of the middle push inner tube and the inner surface of the second tubular portion of the middle push outer tube are sealed by the second sealing member. In the inner push tube set of the present invention, the second sealing member is characterized by having an inclined portion that is inclined toward the rear when viewed from the center axis side so as to move away from the outer surface of the inner push tube second cylindrical portion. In the inner tube set of the present invention, the second sealing member is made of an elastic material and is characterized by having a rear sealing portion located rearward of the inclined portion, on the opposite side to the outer surface of the second cylindrical portion of the inner tube, which has an arc-shaped surface in cross-section along the fore-and-aft direction when no force is applied. [Effects of the Invention]

[0031] According to the present invention, in the thrust method, the space between the inside and outside of the thrust pipe can be reliably sealed. [Brief explanation of the drawings]

[0032] [Figure 1] A cross-sectional view along the central axis showing the structure of the inner tube outer tube in the inner tube set according to an embodiment of the present invention. [Figure 2] A cross-sectional view along the central axis showing the structure of the inner tube in the inner tube set according to an embodiment of the present invention. [Figure 3] This is a process cross-sectional view showing the form during thrust construction work in which an internal thrust pipe set according to an embodiment of the present invention is used. [Figure 4] A cross-sectional view showing the structure of a modified example of the second sealing member used in the inner push tube set according to the embodiment of the present invention. [Figure 5] FIG. 1 is a diagram showing an overview of the thrust method for advancing a thrust pipe underground. [Figure 6] FIG. 2 is a cross-sectional view taken along the central axis showing the structure of the propulsion tube. [Figure 7] A cross-sectional view along the central axis showing the structure of an outer inner tube in a conventional inner tube set. [Figure 8] A cross-sectional view along the central axis showing the structure of a center pusher inner tube in a conventional center pusher tube set. [Figure 9] This is a cross-sectional process view showing the form during thrust construction using a conventional inner thrust pipe set. [Figure 10] 1A to 1C are cross-sectional views showing two types of shapes of the sealing member. DETAILED DESCRIPTION OF THE INVENTION

[0033] The center thrust pipe set according to the embodiment of the present invention comprises an outer center thrust pipe (S-shaped pipe) positioned behind the standard pipe to be advanced in the center thrust method, an inner center thrust pipe (T-shaped pipe) positioned behind the outer center thrust pipe, and a sealing material (sealing member) that seals the space between them. When the jack installed between the outer center thrust pipe and the inner center thrust pipe extends or retracts, the outer center thrust pipe and the inner center thrust pipe slide against each other along the central axis X, and this movement allows the standard pipe in front to advance. This center thrust pipe set remains even after the jacking work is completed, and becomes part of the structure to which the standard pipes are connected. The above points are the same as when using the conventional outer center thrust pipe 110, inner center thrust pipe 120, etc.

[0034] However, the structures of the inner pipe and the outer pipe in the inner pipe set according to the embodiment of the present invention are different from the outer pipe 110 and the inner pipe 120, and accordingly, the configuration of the sealing material (elastic member) used is also different. As a result, the internal space of the standard pipe etc. is tightly sealed from the outside consistently from the start to the end of the jacking work.

[0035] Figures 1 and 2 are cross-sectional views of the outer tube (S-shaped tube) 10 and the inner tube (T-shaped tube) 20 along the central axis X, respectively, and correspond to Figures 7 and 8, respectively, and show the state in which the elastic member is attached. The structure of the standard tube 80 to be advanced here is as shown in Figure 6.

[0036] The outer tube 10 in Figure 1 also has a rearward tube section 11 and a forward tube section 12, both of which are cylindrical and have a central axis X. Furthermore, the outer tube support section 13 is provided on the forward side (left side in the figure) of the forward tube section 12, and the outer tube support section 14 is provided on the rearward side (right side in the figure), both of which are annular and centered on the central axis X. The outer tube rearward tube section 11, the outer tube front section 12, the outer tube front support section 13, and the outer tube rear support section 14 are also integrally formed from metal. Furthermore, the space between the outer tube front support section 13 and the outer tube rear support section 14 is filled with concrete or the like.

[0037] Additionally, a sealing member (front sealing member) 16 is attached to the outer surface of the inner tube front tubular portion 12 of the inner tube 80, as will be described later, to seal the gap between the inner surface of the collar 82 of the front standard tube 80. The sealing member 16 has the same shape as the sealing member 116 (Fig. 10(a)).

[0038] Like the inner push tube 120, the inner push tube 20 in Figure 2 is also formed of metal, with the inner push tube rear tubular section 21, the inner push tube front tubular section 22, the inner push tube front support section 23, and the inner push tube rear support section 24 integrated together. In addition, a filling section 25 made of concrete or the like is formed between the inner push tube front support section 23 and the inner push tube rear support section 24. As with the inner push tube 120 and the outer push tube 110 described above, the inner push tube front tubular section 22 in the inner push tube 20 moves inside the outer push tube rear tubular section 11 in the outer push tube 10 during jacking work.

[0039] Here, the center pusher inner tube front tubular section 22 is configured by connecting a center pusher inner tube first tubular section 22A on the rear side and a center pusher inner tube second tubular section 22B on the front side, and the outer diameter of the center pusher inner tube second tubular section 22B is set smaller than that of the center pusher inner tube first tubular section 22A. For this reason, in Figure 2, a step is formed on the outer surface of the center pusher inner tube front tubular section 22 so that the outer diameter becomes smaller on the front side.

[0040] Corresponding to the structure of the inner tube front tubular portion 22, the inner tube rear tubular portion 11 in the outer tube 10 of Fig. 1 is also configured by connecting the inner tube first tubular portion 11A on the rear side and the inner tube second tubular portion 11B on the front side, and the inner diameter of the outer tube second tubular portion 11B is set smaller than the inner tube first tubular portion 11A. For this reason, in Fig. 1, a step is formed on the inner surface of the outer tube rear tubular portion 11 of the inner tube so that the inner diameter becomes smaller on the front side.

[0041] As shown in Figure 2, while a single type of sealing member 126 was attached to the front cylindrical portion 122 of the inner pusher tube 120, in the inner pusher tube 20, a sealing member (first sealing member) 26 is attached to the first cylindrical portion 22A of the inner pusher tube, and a sealing member (second sealing member) 27 is attached to the second cylindrical portion 22B of the inner pusher tube, corresponding to the structure of the front cylindrical portion 22. In Figure 2, two sealing members 26 are formed, and a lubricant injection hole 25A is provided between the two sealing members 26, similar to the inner pusher tube 120. Here, the sealing member 26 has the same shape as the sealing member 126 (Figure 10(b)), while the sealing member 27 has the same shape as the sealing member 116 or the sealing member 16 (Figure 10(a)).

[0042] In this case, when the inner tube 10 and the outer tube 20 are assembled, the sealing member 26 seals the gap between the outer tube 11A and the inner tube 11A, and the sealing member 27 seals the gap between the outer tube 11A and the inner tube 22B. However, the gap between the outer tube 11A and the inner tube 22 is not sealed by the sealing member 27. In particular, during jacking work, the outer surface of the inner tube 22B, to which the sealing member 27 is attached, may come into contact with the inner surface of the outer tube 11A, but in this case, the gap between these surfaces is not sealed by the sealing member 27.

[0043] With this configuration, the internal space of the standard pipe 80 and each inner push pipe is sealed by the sealing member 26 during the jacking work, and after the jacking work is completed, this space is further sealed by the sealing member 27.

[0044] FIG. 3 corresponds to FIG. 9 and shows the situation when the standard tube 80 is advanced using the outer tube 10 and the inner tube 20. As shown in FIG. 3(1), the standard tube 80 to be advanced is placed in its initial position. Then, as shown in FIG. 3(2), the outer tube 10 and the inner tube 20 are inserted from the rear and attached. Here, the outer tube support 13 of the outer tube 10 abuts against the standard tube body 81 of the front standard tube 80, and the jack 200 and the backing ring 210 are clamped between the outer tube support 14 of the outer tube 10 and the inner tube support 23 of the inner tube 20. In FIG. 3(2), the jack 200 is in its most retracted state. As with FIG. 9, the description of the rear standard tube 80 and the operation of the base push mechanism are omitted.

[0045] In this state, by fixing the rear end of the rear inner pusher tube 20 and extending the jack 200, the front propulsion tube 80 can be advanced as shown in Figure 3(3). After that, by retracting the jack 200 and advancing the inner pusher tube 20 as shown in Figure 3(4), the entire structure of Figure 3(2) will be advanced by the amount of extension of the jack 200. After that, by repeating the operations of Figure 3(3) and (4) again, the propulsion tube 80 can be advanced further by Figure 3(5) and (6), and by repeating the operations of Figure 3(3) and (4), the propulsion tube 80 can be advanced to a predetermined position. Then, in the state shown in Figure 3 (7) where the propulsion tube 80 has been advanced to the predetermined position, the jack 200 and the backing wheel 210 are removed and the inner push tube 20 is advanced, and the inner push tube front support portion 23 of the inner push tube 20 is brought into contact with the outer push tube rear support portion 14 of the outer push tube 10 as shown in Figure 3 (8), and the outer push tube 10 and the collar 81 of the propulsion tube 80 in front of it, the inner push tube 20 and the outer push tube 10 can be fixed by welding or the like.

[0046] 3, the direction of the horizontal force applied to each sealing member is indicated by an arrow, as in Fig. 9. As with sealing member 116 in Fig. 9, a rearward force acts on sealing member 16 only once, as indicated by arrow A1.

[0047] 3(2) to (7), when the jack 200 and the backing ring 210 are installed, the first cylindrical portion 22A and the second cylindrical portion 22B of the inner tube front portion 22 of the inner tube 20 face the first cylindrical portion 11A of the outer tube rear portion 11. Therefore, the gap between them is sealed only by the sealing member 26, and as shown in the figure, the outer diameter of the second cylindrical portion 22B of the inner tube is small, so the sealing member 27 does not come into contact with the first cylindrical portion 11A of the outer tube (rear portion 11).

[0048] In the states (2) to (7) of FIG. 3, the forces acting on the sealing member 26 are in the directions of arrows B1 to B4, similar to the sealing member 126 in FIG. 9. That is, the sealing member 26 is subjected to horizontal forces that alternately change direction multiple times. Therefore, similar to the sealing member 126 described above, the sealing member 26 may deteriorate due to wear during this time. Furthermore, because forces that alternate in direction are applied in this manner, the shape of the sealing member 26 is as shown in FIG. 10(b), as described above. Meanwhile, the sealing member 27 does not come into contact with the inner push outer tube rear tubular portion 11 in the states (2) to (7) of FIG. 3, and therefore no deterioration due to wear occurs.

[0049] On the other hand, in the state of (8) in FIG. 3, regarding the point where the first cylinder part 22A of the forward cylinder part 22 of the middle push inner tube 20 in the middle push inner tube 20 faces the first cylinder part 11A of the rearward cylinder part 11 of the middle push outer tube, it is the same as the above case. However, in front of that, the second cylinder part 22B of the middle push inner tube is set to face the second cylinder part 11B of the middle push outer tube, and the space between them is sealed by the sealing member 27. In this case, the direction of the force acting on the sealing member 27 is backward as shown by C1. In FIG. 3, the force acts on the sealing member 27 in the horizontal direction only once. Therefore, the sealing member 27 has the same shape as the above sealing member 116 or sealing member 16 (FIG. 10(a)), and a similar inclined part is provided. Thereby, the space between the second cylinder part 22B of the middle push inner tube and the second cylinder part 11B of the middle push outer tube is strongly sealed, and it is also easy to form the state of (8) in FIG. 3. At this time, in the sealing member 27, different from the sealing member 26, deterioration due to wear has not occurred.

[0050] Therefore, even if the space between the first cylinder part 22A of the middle push inner tube and the first cylinder part 11A of the middle push outer tube is not sufficiently sealed by the sealing member 26 in the state of (8) in FIG. 3, the space on the central axis X side is surely sealed by the front sealing member 27. For this reason, for example, subsequent welding operations (such as welding over the entire circumference) for sealing between the forward cylinder part of the middle push inner tube and the rearward cylinder part of the middle push outer tube become unnecessary. This point is the same as the joining between the standard tubes 80 and between the standard tube 80 and the middle push tube.

[0051] FIG. 4 is a diagram showing the shape of a sealing member 28 which is a modified example of the sealing member (second sealing member) 27 corresponding to FIG. 10. This sealing member 28 is composed of an elastic body, and here the shape when no force is applied (not in contact with the middle push outer tube 10 side) is shown. Even in this case, the directionality is considered in the same way as the above sealing member 116, etc., and two inclined parts 28A are provided. At this time, on the lower side (the side of the second cylinder part 22B of the middle push inner tube), a cavity 28B is formed in order to facilitate the deformation near the inclined part 28A at the stage of (8) in FIG. 3 where the middle push inner tube 20 is fixed to the middle push outer tube 10.

[0052] To further secure the seal between the outer tube 11B and the inner tube 22B after installation, a rear sealing portion 28C is provided at the rear, with an approximately arc-shaped upper surface (opposite the inner tube 22B) in the cross section of FIG. 4 . When inserting the inner tube 22B into the outer tube 11B, the rear sealing portion 28C abuts the inner surface of the outer tube 11B after the inclined portion 28A. Therefore, even if foreign matter is present on the inner surface of the outer tube 11B, it is removed by the inclined portion 28A, thereby preventing the rear sealing portion 28C from being affected. Therefore, the sealing member 28 can further securely and firmly seal the outer tube 10 and the inner tube after installation. A similar sealing member may also be used to connect standard tubes 80 together.

[0053] The steps in the process of Figure 3 are essentially the same as those in the process of Figure 9 using a conventional thrust pipe, except that the outer thrust pipe and inner thrust pipe used are changed. This makes it possible to easily carry out the above-mentioned thrust work.

[0054] In Figure 3, the sealing member 27 does not contact the inner surface of the inner tube first tubular section 11A in states (2) to (7). However, they may be configured so that they lightly contact each other to the extent that deterioration due to wear does not occur. Even in this case, the internal space is still sealed by the sealing member 26. Furthermore, in this case, if the sealing member 26 deteriorates during the jacking operation, the sealing member 27 can prevent moisture and other substances from penetrating forward. Even if the sealing member 27 also deteriorates due to wear, the two-stage structure of the inner tube front tubular section 22 described above makes the gap between the outer surface of the inner tube second tubular section 22B and the inner surface of the inner tube first tubular section 11A wider than the gap between the outer surface of the inner tube first tubular section 22A and the inner surface of the inner tube first tubular section 11A, making this deterioration negligible compared to the gap between the sealing member 26 and the sealing member 26.

[0055] Furthermore, in the above example, the standard tube, the inner tube, the outer tube, and the inner tube are assumed to be approximately cylindrical (the cross-sectional shape perpendicular to the central axis X is circular), but as long as they can be combined in the same manner as above, their cross-sectional shapes are arbitrary, and even in this case, it is clear that the same positional relationship between the inner and outer surfaces can be achieved and similar sealing members can be used.

[0056] In the above example, the pressure applied to the outer and inner pipes during jacking work was applied by a jack or the like between the rear support part of the outer pipe and the front support part of the inner pipe, but the structure for this purpose can be appropriately set for the outer and inner pipes. Also, the rear support part of the outer pipe and the front support part of the inner pipe were assumed to be annular when viewed from the front to back, but these shapes can be appropriately set as long as they have surfaces perpendicular to the central axis so that the process shown in Figure 3 can be realized and they can be formed integrally with other parts.

[0057] The present invention has been described above based on an embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0058] 10, 110 Medium extrusion tube (S type tube) 11, 111 Rear cylindrical part of inner push-out tube 11A Inner push outer tube 1st cylindrical part 11B Middle extrusion outer tube 2nd cylinder part 12, 112 Front cylinder part of inner extrusion tube 13, 113 Front support part of inner push outer tube 14, 114 Rear support part of inner push outer tube 15, 25, 115, 125 Filling section 16, 116 Sealing member (front sealing member) 20, 120 Medium push inner tube (T type tube) 21, 121 Rear cylinder part of inner inner tube 22, 122 Front section of inner tube 22A Inside inner tube 1st cylinder part 22B Inner inner tube 2nd cylindrical part 23, 123 Front support part of inner inner tube 24, 124 Middle push inner tube rear support part 25A, 125A Lubricant injection hole 26 Sealing member (first sealing member) 28 Sealing member (second sealing member) 28A Slope 28B Cavity 28C Rear sealing part 80, 80A~80C standard tube 81 Standard tube body 81A Small diameter section 82 Color 85 Blade mouth 90 Middle push mechanism 116A Inclined section 200 Jack (pressure device) 210 Backing Ring G Ground S shaft X center axis

Claims

1. A center pusher pipe set used in a center pusher method for advancing a cylindrical standard pipe having a central axis along the front-to-rear direction underground, the center pusher pipe set comprising: an outer center pusher pipe arranged behind the standard pipe to advance the standard pipe; and an inner center pusher pipe arranged behind the outer center pusher pipe, movable along the central axis relative to the outer center pusher pipe, to advance the outer center pusher pipe and the standard pipe, both of which have cylindrical structures coaxial with the standard pipe; The inner tube has a front cylindrical portion at the front that is cylindrical and coaxial with the standard tube, and the outer tube has a rear cylindrical portion at the rear that is cylindrical and coaxial with the standard tube, the inner tube front cylindrical portion is movable inside the outer tube rear cylindrical portion, the inner tube front cylindrical portion includes an inner tube first cylindrical portion provided on the rear side, and an inner tube second cylindrical portion provided on the front side and having an outer diameter smaller than that of the inner tube first cylindrical portion, The inner tube rear cylindrical portion of the inner tube is provided with: an inner tube first cylindrical portion located at the rear side, the inner diameter of which is larger than the outer diameter of the inner tube first cylindrical portion; and an inner tube second cylindrical portion located at the front side, the inner diameter of which is smaller than the inner tube first cylindrical portion and larger than the outer diameter of the inner tube second cylindrical portion. A center push tube set characterized by being provided with a first sealing member that seals the gap between the outer surface of the first cylindrical portion of the center push inner tube and the inner surface of the first cylindrical portion of the center push outer tube, and a second sealing member that seals the gap between the outer surface of the second cylindrical portion of the center push inner tube and the inner surface of the second cylindrical portion of the center push outer tube.

2. The standard tube is advanced by applying pressure to the outer and inner tubes using a pressure device provided between the outer and inner tubes. the first sealing member is attached to the outer surface of the first cylindrical portion of the inner push tube, and the second sealing member is attached to the outer surface of the second cylindrical portion of the inner push tube, A center pusher tube set as described in claim 1, characterized in that when the standard tube is advanced, the outer surface of the first cylindrical portion of the center pusher inner tube at the location where the first sealing member is attached and the outer surface of the second cylindrical portion of the center pusher inner tube at the location where the second sealing member is attached face the inner surface of the first cylindrical portion of the center pusher outer tube.

3. When the outer surface of the first cylindrical portion of the inner tube where the first sealing member is attached and the outer surface of the second cylindrical portion of the inner tube where the second sealing member is attached face the inner surface of the first cylindrical portion of the outer tube, The inner tube set according to claim 2, characterized in that the first sealing member abuts against the inner surface of the first cylindrical portion of the outer tube, and the second sealing member is configured not to abut against the inner surface of the first cylindrical portion of the outer tube.

4. the outer tube includes a rear support portion for the outer tube, the rear support portion having a surface extending in a direction perpendicular to the central axis and being pressurized from the rear side; The second cylindrical portion of the inner tube is connected to the rear support portion of the outer tube at the front and to the first cylindrical portion of the outer tube at the rear, the inner tube includes an inner tube front support portion that has a surface extending in a direction perpendicular to the central axis and is pressurized from the front side; the second cylindrical portion of the inner push tube is connected to the front support portion of the inner push tube and to the first cylindrical portion of the inner push tube at its rear, 4. The inner push tube set according to claim 2, wherein the pressure device is configured to be provided between the outer push tube rear support portion and the inner push tube front support portion.

5. A center pusher tube set as described in claim 4, characterized in that when the center pusher outer tube rear support portion and the center pusher inner tube front support portion of the center pusher inner tube are abutted together, the outer surface of the center pusher inner tube second tubular portion at the point where the second sealing member is attached faces the inner surface of the center pusher outer tube second tubular portion, and the outer surface of the center pusher inner tube second tubular portion and the inner surface of the center pusher outer tube second tubular portion are sealed by the second sealing member.

6. The center push tube set according to claim 2 or 3, characterized in that the second sealing member has an inclined portion that is inclined toward the rear when viewed from the center axis side so as to move away from the outer surface of the center push inner tube second cylindrical portion.

7. The second sealing member is made of an elastic material and is provided rearward of the inclined portion. A center push tube set as described in claim 6, characterized in that it is provided with a rear sealing portion on the opposite side of the outer surface of the center push inner tube second cylindrical portion, which has a surface that is arc-shaped in cross-section along the front-to-back direction when no force is applied.

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