Center push tube set

Abstract

To reliably seal between the inside and outside of a standard tube in a center thrust method. [Solution] The center push inner tube front tubular portion 22 is formed by connecting the center push inner tube first tubular portion 22A on the rear side and the center push inner tube second tubular portion 22B on the front side, and the outer diameter of the center push inner tube second tubular portion 22B is set to be smaller than that of the center push inner tube first tubular portion. For this reason, in FIG. 2, a step is formed on the outer surface of the center push inner tube front tubular portion 22 so that the outer diameter becomes smaller on the front side. A sealing member 26 is attached to the center push inner tube first tubular portion 22A, and a sealing member 27 is attached to the center push inner tube second tubular portion 22B. When the center push outer tube and the center push inner tube 20 are combined, the sealing member 26 seals the gap between the center push outer tube first tubular portion and the center push inner tube first tubular portion 22A, and the sealing member 27 seals the gap between the center push outer tube second tubular portion and the center push inner tube second tubular portion 22B.

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 in thrusting work for laying thrust pipes, and a sealing member that seals the space between them. [Background technology]

[0002] Cylindrical Hume pipes (jacking pipes) made of reinforced concrete or the like are used by being installed underground, etc., with many of them connected in the central axial direction. In this case, when constructing a structure in which many jacking pipes are connected horizontally from the side of a shaft formed underground, it is necessary to advance the tip of the jacking pipe forward one by one. For this purpose, a jack or the like can be used, but it is often difficult to install all the mechanisms for this purpose within the limited space of the shaft.

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

[0004] The center thrust method uses a center thrust pipe with a structure different from that of a normal jacking pipe (standard pipe), and pressurizes the center thrust pipe with a jack to indirectly pressurize the standard pipe. That is, jacking pipes are roughly divided into a standard pipe that becomes the main body after construction, and a center thrust pipe that is used for jacking construction, and there are two types of center thrust pipes, which will be described later. The center thrust pipe remains attached to the standard pipe after construction is completed, so it is shaped so as not to be an obstacle when the standard pipe is used. In addition, when the work of advancing the jacking pipe is performed as described above, the space inside the standard pipe or the center thrust pipe is configured to be sealed from the outside so that water or mud does not enter the inside of the pipe. Since the center thrust pipe remains as described above even after construction is completed, this sealed state needs to be permanently maintained even after construction is completed. Examples of specific structures for this purpose are described in Patent Documents 1 and 2, for example.

[0005] FIG. 5 is a diagram showing a schematic diagram of the overall configuration of the center push method. In the figure, a plurality of standard pipes 80 are connected and extended 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 here in a simplified form. The standard pipes 80 have an approximately cylindrical shape, and each standard pipe 80 is connected in the direction of the central axis, and FIG. 5 shows a cross section along the central axis X. Here, a cutting edge 85 is attached to the tip of the leading (left) standard pipe 80A, and it can be advanced by applying pressure to the left side in the figure. For this purpose, a center push mechanism 90 is provided between the standard pipes 80B and 80C in the figure. The center push mechanism 90 is fixed to the rear standard pipe 80C and applies pressure to the front standard pipe 80B forward, thereby advancing the leading standard pipe 80A underground. Although not shown in FIG. 5, a base push mechanism that advances from the vertical shaft S side is also provided in the vertical shaft S.

[0006] Specifically, the center push mechanism 90 is composed of a center push outer tube (S-shaped tube) on the front side, a center push inner tube (T-shaped tube) on the rear side, 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 of the center push outer tube 110 and the center push inner tube 120, corresponding to Figure 5, taken along the central axis X. Figures 7 and 8 show a state in which an elastic member, which will be described later, is attached.

[0007] In FIG. 6, the standard pipe 80 comprises a standard pipe body 81 made of concrete (reinforced concrete) having a substantially cylindrical shape, and a metal collar 82 attached to the rear of the body so as to protrude rearward. The outer diameter of the standard pipe body 81 and the outer diameter of the collar 82 are set to be equal. The leading end of the standard pipe body 81 is a small diameter portion 81A that is slightly smaller in diameter so as to be accommodated in the collar 82 of the standard pipe 80 in front of it, and this allows the standard pipes 80 to be connected to each other using the collar 82 and fixed from the inside (the central axis X side). Although not shown in the figure, a seal member (sealing member) is attached to the small diameter portion 81A to seal the gap between the outer surface of the small diameter portion 81A and the collar 82 of the standard pipe 80 in front of it, but the description of this member is omitted. This prevents soil and moisture from entering the inside of the standard pipe 80 after the connection underground.

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

[0009] In addition, 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 82 of the standard tube 80 at the front, as described below.

[0010] 8, like the inner pusher outer tube 110, the inner pusher inner tube rear tubular portion 121, the inner pusher inner tube front tubular portion 122, the inner pusher inner tube front support portion 123, and the inner pusher inner tube rear support portion 124 are integrally formed of metal. In addition, a filling portion 125 made of concrete or the like is formed between the inner pusher inner tube front support portion 123 and the inner pusher inner tube rear support portion 124.

[0011] A sealing member 126 is attached to the outer surface of the inner push inner tube front cylinder portion 122 to seal the gap between the inner surface of the inner push outer tube rear cylinder portion 111 of the front inner push outer tube 110 as described below. Here, two sealing members 126 are provided along the central axis X direction, and between them, a lubricant injection hole 125A for injecting lubricant from the inside to the outside is formed penetrating the filling portion 125 and the inner push inner tube front cylinder portion 122. In FIG. 8, the lubricant injection holes other than 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 a plurality of holes distributed in the circumferential direction.

[0012] Fig. 9 shows a specific configuration for actually moving the standard tube 80 forward using the above-mentioned inner pusher tube 110 and inner pusher tube 120. Here, only the portion corresponding to the upper portion in Figs. 6 to 8 is shown, and the small diameter portion 81A of the standard tube 80 is omitted.

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

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

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

[0016] After that, in the state of Fig. 9 (7) where the standard tube 80 has been advanced to the target position, the jack 200 and the backing wheel 210 are removed, and the inner push tube 120 is advanced as shown in Fig. 9 (8) so that the inner push tube front support part 123 of the inner push tube 120 abuts against the inner push tube rear support part 114 of the outer push tube 110, and the outer push tube 110 and the collar 81 of the standard tube 80 in front of it, the inner push tube 120 and the outer push 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 push tube 120, so that the front standard tube 80, the outer push tube 110, the inner push tube 120 and the rear standard tube 80 are fixed.

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

[0018] As described above, during the above construction, in order to prevent soil and moisture from entering the inside of the standard pipe 80 (the space on the central axis X side), the sealing member 116 is attached to the inner pipe 110 side and the sealing member 126 is attached to the inner pipe 120 side. In the state shown in FIG. 9, the sealing member 116 seals between the outer surface of the outer pipe front tube 112 and the inner surface of the collar 82 of the standard pipe 80, and the sealing member 126 seals between the outer surface of the inner pipe front tube 122 and the inner surface of the inner pipe rear tube 111 of the outer pipe 110. These sealing members are made of elastic material, and their elastic force seals between the surfaces they abut, suppressing the intrusion of soil and moisture. The state in which the space on the central axis X side is sealed by the sealing members 116 and 126 is maintained even in the state shown in FIG. 9 (8) after the jacking construction is completed. As shown in Figures 7 and 8, these sealing members are attached in advance before the installation of the inner tube 110 and the outer tube 120.

[0019] 9, in addition to a force compressing each sealing member in the up-down 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 inner tube 110, and the 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] JP 2014-70479 A [Patent Document 2] JP 2012-246678 A Summary of the Invention [Problem to be solved by the invention]

[0021] In Fig. 9, arrows are shown indicating the direction of the force applied to the sealing member along the horizontal direction (direction along the central axis X) as seen from the sealing member side (the relative movement direction of the surface that the sealing member abuts on the upper side) when performing each process. In Fig. 9(2), the inner tube 110 and the inner tube 120 are inserted from the rear side (right side), so a force acts on the sealing member 116 toward the rear side (right side) as shown by arrow A1 and on the sealing member 126 toward the rear side (right side). From Fig. 9(3) onwards, the positional relationship between the outer tube 110 and the standard tube 80 (collar 81) does not change, so from this point onwards, no force is applied to the sealing member 116 along the horizontal direction.

[0022] On the other hand, in (3) of Fig. 9, as the jack 200 extends, a force acts on the sealing member 126 toward the front (left side) as indicated by arrow B2, and thereafter, in (4), a force acts on the sealing member 126 toward the rear (right side) as indicated by arrow B3. Fig. 9 (5) and (6) are similar to Fig. 9 (3) and (4). In addition, in the final form, shown in Fig. 9 (8), a force acts on the sealing member 126 toward the rear (right side) as indicated by arrow B4.

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

[0024] 10(a) and 10(b) are cross-sectional views along the front-rear direction, showing the sealing member 116, the sealing member 126 and the surrounding structure in Figs. 7 and 8 in simplified and enlarged form. Here, the description of the structure serving as the stopper is omitted. As described above, the force toward the rear (to the right) 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 body having a left-right asymmetric shape can be used, which is provided with a plurality of inclined portions 116A inclined toward the rear side so as to move away from the surface to which it is attached (the outer surface of the inner push outer tube front tubular portion 112). This makes it easier to attach the inner push 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 sealing caused by the inclined portions 116A.

[0025] On the other hand, as described above, the sealing member 126 is subjected to horizontal forces that alternately change direction multiple times, and therefore 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 in a 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) in FIG. 9, a lubricant is injected from the inside of the inner pusher tube 120 to facilitate the sliding of the sealing member 126, making it possible to easily perform the steps in FIG. 9 and to suppress deterioration of the sealing member 126.

[0026] In this case, the sealing member 126 seals between the outer surface of the inner tube inner periphery 122 and the inner surface of the outer tube outer periphery 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, the number of cycles in which the force is applied to the sealing member 126 as described above may exceed 1000 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 part 122 and the outer tube rear part 111 must be permanently sealed not only during construction as shown in Fig. 9, but also after that. For this reason, after the configuration shown in Fig. 9(8) was achieved, it became necessary to seal the gap between the inner tube front part 122 and the outer tube rear part 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 has an object to solve the above problems. [Means for solving the problem]

[0030] The inner push tube set of the present invention is used in a inner push tube construction method in which a cylindrical standard tube having a central axis along the front-to-rear direction is advanced underground, and includes an outer inner push tube arranged behind the standard tube to advance the standard tube, and an inner inner push tube arranged behind the outer inner push tube and movable along the central axis relative to the outer inner push tube to advance the outer inner push tube and the standard tube, both of which have a cylindrical structure coaxial with the standard tube, the inner inner push tube has a front cylindrical portion at the front that is cylindrical and coaxial with the standard tube, and the outer inner push tube has a rear cylindrical portion at the rear that is cylindrical and coaxial with the standard tube, a pressure device provided between a center push inner tube front support portion provided in front of the center push inner tube front tubular portion in the center push inner tube and a center push outer tube rear support portion provided in front of the center push outer tube rear tubular portion in the center push outer tube, the center push outer tube is pressurized forward and the center push inner tube is pressurized rearward, respectively, so that the center push outer tube front support portion provided in front of the center push outer tube rear support portion in the center push outer tube is formed to move the standard tube forward, and the center push inner tube is movable in the front-back direction relative to the center push outer tube with the center push inner tube front tubular portion inside the center push outer tube rear tubular portion, The middle press inner tube front tubular portion comprises a middle press inner tube first tubular portion provided on the rear side, and a middle press inner tube second tubular portion provided on the front side and having an outer diameter smaller than that of the middle press inner tube first tubular portion, and the middle press outer tube rear tubular portion comprises a middle press outer tube first tubular portion provided on the rear side and having an inner diameter larger than the outer diameter of the middle press inner tube first tubular portion, and a middle press outer tube second tubular portion provided on the front side, having an inner diameter smaller than that of the middle press outer tube first tubular portion and an inner diameter larger than the outer diameter of the middle press inner tube second tubular portion, A first sealing member is attached to the outer surface of the first cylindrical portion of the middle press inner tube, and a second sealing member is attached to the outer surface of the second cylindrical portion of the middle press inner tube. When the middle press outer tube moves in the front-to-rear direction relative to the middle press inner tube, the inner surface of the first cylindrical portion of the middle press outer tube faces the location where the first sealing member is attached on the outer surface of the first cylindrical portion of the middle press inner tube and the location where the second sealing member is attached on the outer surface of the second cylindrical portion of the middle press inner tube. and a second state in which the inner surface of the middle press outer tube second cylindrical portion faces a portion of the outer surface of the middle press inner tube second cylindrical portion to which the second sealing member is attached. In the first state, the inner surface of the middle press outer tube first cylindrical portion and the outer surface of the middle press inner tube first cylindrical portion are sealed by the first sealing member, and the inner surface of the middle press outer tube first cylindrical portion and the outer surface of the middle press inner tube second cylindrical portion are not sealed by the second sealing member. In the second state, the inner surface of the middle press outer tube second cylindrical portion and the outer surface of the middle press inner tube second cylindrical portion are sealed by the second sealing member. Characterized by 。 The inner push tube set of the present invention is In the first state, The first sealing member is set to come into contact with the inner surface of the first cylindrical portion of the inner tube, and the second sealing member is set not to come into contact with the inner surface of the first cylindrical portion of the inner tube. 。 The inner tube set of the present invention is a rear part of the inner tube in the outer tube. Support part When the inner tube front support portion of the inner tube is brought into contact with the inner tube front support portion of the inner tube, The second state is established. It is characterized by: In the inner push tube set of the present invention, the second sealing member is On the surface opposite to the side where the central axis is located, from the front to the rear It is characterized in that it has an inclined portion that is inclined so as to be away from the outer surface of the second cylindrical portion of the inner pusher inner tube. In the inner push tube set of the present invention, the second sealing member is made of an elastic material, and is disposed behind the inclined portion and on the outer surface of the second cylindrical portion of the inner push tube. The side withOn the opposite side to the rear sealing portion, the rear sealing portion has a surface that is arc-shaped in cross section along the front-rear direction when no force is applied. Effect 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 description of the drawings]

[0032] [Figure 1] A cross-sectional view along the central axis showing the structure of an inner tube in an inner tube set according to an embodiment of the present invention. [Diagram 2] A cross-sectional view along the central axis showing the structure of a center pusher inner tube in a center pusher tube set according to an embodiment of the present invention. [Diagram 3] This is a process cross-sectional view showing the form during thrust construction work in which a center thrust pipe set in accordance with an embodiment of the present invention is used. [Figure 4] A cross-sectional view showing the structure of a modified second sealing member used in an inner push tube set according to an embodiment of the present invention. [Diagram 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] This is a cross-sectional view along the central axis showing the structure of an outer inner tube in a conventional inner tube set. [Figure 8] This is 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 process cross-sectional view showing the form during tunneling work in which a conventional thrust pipe set is used. [Figure 10] 1A to 1C are cross-sectional views showing two types of shapes of a sealing member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0034] However, the structure of the inner pipe and the outer pipe in the inner pipe set according to the embodiment of the present invention is different from the outer pipe 110 and the inner pipe 120, and the configuration of the sealing material (elastic member) used is also different. This ensures that the internal space of the standard pipe, etc. is tightly sealed from the outside from the start to the end of the tunneling work.

[0035] Figures 1 and 2 are cross-sectional views along the central axis X of the inner tube (S-shaped tube) 10 and the inner tube (T-shaped tube) 20, 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] In the inner pipe 10 of FIG. 1, the inner pipe rear tubular portion 11 on the rear side and the inner pipe front tubular portion 12 on the front side are provided, both of which are cylindrical with the central axis X as their central axis, and further, the inner pipe front support portion 13 on the front side (left side in the figure) of the inner pipe front tubular portion 12 and the inner pipe rear support portion 14 on the rear side (right side in the figure), both of which are annular with the central axis X as their center, are provided. The inner pipe rear tubular portion 11, the inner pipe front tubular portion 12, the inner pipe front support portion 13, and the inner pipe rear support portion 14 are also integrally formed of metal. In addition, the space between the inner pipe front support portion 13 and the inner pipe rear support portion 14 is filled with concrete or the like as a filling portion 15.

[0037] In addition, a sealing member (front sealing member) 16 is attached to the outer surface of the inner tube front cylinder portion 12, as described below, to seal the gap with 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 described above (Figure 10(a)).

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

[0039] Here, the center push inner tube front tubular portion 22 is configured by connecting the center push inner tube first tubular portion 22A on the rear side and the center push inner tube second tubular portion 22B on the front side, and the outer diameter of the center push inner tube second tubular portion 22B is set smaller than the center push inner tube first tubular portion 22A. For this reason, in Fig. 2, a step is formed on the outer surface of the center push inner tube front tubular portion 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 inner tube outer tube 10 in 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 inner 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 inner tube rear tubular portion 11 in the inner tube outer tube such that the inner diameter becomes smaller on the front side.

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

[0042] In this case, when the inner tube 10 and the inner tube 20 are assembled, the sealing member 26 seals between the first cylindrical portion 11A of the outer tube and the first cylindrical portion 22A of the inner tube, and the sealing member 27 seals between the second cylindrical portion 11B of the outer tube and the second cylindrical portion 22B of the inner tube. However, the sealing member 27 is not configured to seal between the first cylindrical portion 11A of the outer tube and the front cylindrical portion 22 of the inner tube. In particular, during the jacking work, the outer surface of the second cylindrical portion 22B of the inner tube to which the sealing member 27 is attached may face the inner surface of the first cylindrical portion 11A of the outer tube, but in this case, the sealing member 27 is not configured to seal between these surfaces.

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

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

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

[0046] In Fig. 3, the direction of the horizontal force applied to each sealing member is indicated by an arrow, similar to 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] Here, as shown in (2) to (7) of Figure 3, when the jack 200 and the backing wheel 210 are installed, the first cylinder portion 22A of the middle push inner tube and the second cylinder portion 22B of the middle push inner tube of the front cylinder portion 22 of the middle push inner tube 20 face the first cylinder portion 11A of the middle push outer tube of the rear cylinder portion 11. Therefore, the gap between them is only sealed by the sealing member 26, and as shown in the figure, the outer diameter of the second cylinder portion 22B of the middle push inner tube is small, so the sealing member 27 does not come into contact with the first cylinder portion 11A of the middle push outer tube (rear cylinder portion 11 of the middle push outer tube).

[0048] In the states (2) to (7) of FIG. 3, the forces acting on the sealing member 26 are in the directions of the 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 many times. Therefore, similar to the sealing member 126 described above, the sealing member 26 may deteriorate due to wear during this time. In addition, because forces that change direction alternately are applied in this way, the shape of the sealing member 26 is as shown in FIG. 10(b) as described above. On the other hand, 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, the first cylinder 22A of the inner tube front part 22 of the inner tube 20 faces the first cylinder 11A of the outer tube rear part 11 of the inner tube, as in the above case, but the second cylinder 22B of the inner tube is set to face the second cylinder 11B of the outer tube, and the gap between them is sealed by the sealing member 27. In this case, the direction of the force acting on the sealing member 27 is toward the rear, as shown by C1. In FIG. 3, the force acts on the sealing member 27 in the horizontal direction only once. For this reason, the sealing member 27 has the same shape (FIG. 10(a)) as the sealing member 116 or the sealing member 16, and has the same inclined portion. This strongly seals the gap between the second cylinder 22B of the inner tube and the second cylinder 11B of the outer tube, and also makes it easy to form the shape of FIG. 3(8). At this time, unlike the sealing member 26, the sealing member 27 does not experience deterioration due to wear.

[0050] 3(8) in the state where the sealing member 26 does not adequately seal the gap between the first cylindrical portion 22A of the inner tube and the first cylindrical portion 11A of the outer tube, the space on the central axis X side is reliably sealed by the sealing member 27 in front of it. This eliminates the need for welding work (e.g., welding over the entire circumference) to seal the gap between the front cylindrical portion of the inner tube and the rear cylindrical portion of the outer tube. This is the same as for the joining of standard tubes 80 together and between a standard tube 80 and a middle tube.

[0051] 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, in correspondence with FIG. 10. This sealing member 28 is made of an elastic body, and the shape shown here is when no force is applied (no contact with the inner push outer tube 10). In this case, too, directionality is taken into consideration, as with the sealing member 116 and the like, and two inclined portions 28A are provided. At this time, a cavity 28B is formed on the lower side (the inner push inner tube second cylindrical portion 22B side) to facilitate deformation near the inclined portion 28A at the stage of FIG. 3 (8) when the inner push inner tube 20 is fixed to the inner push outer tube 10.

[0052] In addition, in order to further firmly seal between the second cylinder part 11B of the inner tube and the second cylinder part 22B of the inner tube after fixing, a rear sealing part 28C is provided at the rear, whose upper side (opposite the second cylinder part 22B of the inner tube) has a substantially arcuate surface in the cross section of FIG. 4. When the second cylinder part 22B of the inner tube is inserted into the second cylinder part 11B of the inner tube, the rear sealing part 28C abuts against the inner surface of the second cylinder part 11B of the inner tube after the inclined part 28A. Therefore, even if there is a foreign object on the inner surface of the second cylinder part 11B of the inner tube, it is removed by the inclined part 28A in front of it, thereby preventing the rear sealing part 28C from being affected. Therefore, the sealing member 28 can further reliably and firmly seal between the outer tube 10 and the inner tube after construction. A similar sealing member may be used to connect standard tubes 80 together.

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

[0054] In FIG. 3, the sealing member 27 does not come into contact with the inner surface of the first cylindrical portion 11A of the inner tube in the states (2) to (7), but they may be configured to come into light contact 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. In addition, in this case, if the sealing member 26 deteriorates during the jacking work, the sealing member 27 can stop moisture and the like that has invaded the front. Even if the sealing member 27 also deteriorates due to wear at this time, the two-stage structure of the inner tube front portion 22 of the inner tube inner pipe as described above makes the gap between the outer surface of the second cylindrical portion 22B of the inner tube inner pipe and the inner surface of the first cylindrical portion 11A of the inner tube inner pipe wider than the gap between the outer surface of the first cylindrical portion 22A of the inner tube inner pipe and the inner surface of the first cylindrical portion 11A of the inner tube inner pipe, so that this deterioration can be made negligible compared to the sealing member 26.

[0055] In addition, in the above example, the standard tube, the inner tube, the outer tube, the inner tube, etc. are assumed to be approximately cylindrical in shape (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 a similar positional relationship between the inner and outer surfaces can be realized and a similar sealing member can be used.

[0056] In the above example, the pressure was applied to the outer and inner tubes during the tunneling work by using jacks between the rear support part of the outer tube and the front support part of the inner tube, but the structure for this can be set appropriately in the outer and inner tubes. The rear support part of the outer tube and the front support part of the inner tube are annular when viewed from the front-rear direction, but the shapes of these can be set appropriately as long as they have surfaces perpendicular to the central axis so that the process of Figure 3 can be realized and 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 Back Ring G. Ground S Shaft X center axis

Claims

1. A center push tube set used in a center push tube construction method in which a cylindrical standard tube having a central axis along a front-to-rear direction is advanced underground, the center push tube set having an outer center push tube arranged behind the standard tube to advance the standard tube, and an inner center push tube arranged behind the outer center push tube, movable along the central axis relative to the outer center push tube, and advancing the outer center push tube and the standard tube, both of which have a cylindrical structure coaxial with the standard tube, The inner tube has a front tube portion at the front, the front tube portion being cylindrical and coaxial with the standard tube, and the outer tube has a rear tube portion at the rear, the rear tube portion being cylindrical and coaxial with the standard tube, The inner tube is pressurized forward and the inner tube is pressurized backward by a pressure device provided between the inner tube front support portion provided in front of the inner tube front tubular portion of the inner tube and the outer tube rear support portion provided in front of the outer tube rear tubular portion of the outer tube, so that the outer tube is pressed forward and the inner tube is pressed backward, respectively, so that the outer tube front support portion provided forward of the outer tube rear support portion of the outer tube is formed to move the standard tube forward, the inner pusher tube is movable in a front-rear direction relative to the outer pusher tube with the inner pusher tube front tubular portion being inside the outer pusher tube rear tubular portion, The inner tube front tubular portion includes a first inner tube portion provided on the rear side, and a second inner tube portion provided on the front side and having an outer diameter smaller than that of the first inner tube portion, The inner tube rear tubular portion includes an inner tube first tubular portion provided at the rear side and having an inner diameter larger than the outer diameter of the inner tube first tubular portion, and an inner tube second tubular portion provided at the front side and having an inner diameter smaller than the inner tube first tubular portion and an inner diameter larger than the outer diameter of the inner tube second tubular portion, A first sealing member attached to an outer surface of the first cylindrical portion of the inner push tube; A second sealing member attached to an outer surface of the second cylindrical portion of the inner push tube; was established, When the outer tube moves forward and backward relative to the inner tube, a first state in which the inner surface of the first cylindrical portion of the inner tube faces a portion of the outer surface of the first cylindrical portion of the inner tube where the first sealing member is attached and a portion of the outer surface of the second cylindrical portion of the inner tube where the second sealing member is attached; a second state in which the inner surface of the first cylindrical portion of the inner press outer tube faces the portion of the outer surface of the first cylindrical portion of the inner press inner tube where the first sealing member is attached, and the inner surface of the second cylindrical portion of the inner press outer tube faces the portion of the outer surface of the second cylindrical portion of the inner press inner tube where the second sealing member is attached; Take In the first state, the inner surface of the first cylindrical portion of the inner tube outer tube and the outer surface of the first cylindrical portion of the inner tube inner tube are sealed by the first sealing member, and the inner surface of the first cylindrical portion of the inner tube outer tube and the outer surface of the second cylindrical portion of the inner tube inner tube are not sealed by the second sealing member, A center push tube set characterized in that in the second state, the inner surface of the center push outer tube second cylindrical portion and the outer surface of the center push inner tube second cylindrical portion are sealed by the second sealing member.

2. The inner tube set described in claim 1, characterized in that in the first state, the first sealing member abuts against the inner surface of the inner tube first tubular portion, and the second sealing member is set not to abut against the inner surface of the inner tube first tubular portion.

3. A center push tube set as described in claim 1 or 2, characterized in that the second state is achieved when the center push outer tube rear support portion of the center push outer tube and the center push inner tube front support portion of the center push inner tube are abutted against each other.

4. A center push tube set as described in claim 1 or 2, characterized in that the second sealing member has an inclined portion on the surface opposite to the side where the central axis is located, which is inclined so as to move away from the outer surface of the center push inner tube second cylindrical portion as it moves from the front to the rear.

5. The second sealing member is made of an elastic material and is provided behind the inclined portion. A center push tube set as described in claim 4, characterized in that it is provided with a rear sealing portion on the side opposite to the side where the outer surface of the center push inner tube second cylindrical portion is located, the rear sealing portion having a surface that is arc-shaped in cross-sectional shape along the front-to-rear direction when no force is applied.

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