Sheath connection method and sheath connection structure

Abstract

The present invention provides a sheath connection method and sheath connection structure that can efficiently connect sheaths in the gaps between precast panels used to construct a floor slab. [Solution] A sheath connection method for connecting sheaths 9 for inserting PC steel materials 7 between multiple panels 3 that constitute a floor slab 1 comprises a panel installation step of installing a panel 3A having a sheath 9A and a panel 3B adjacent to panel 3A and having a sheath 9B, with a gap of the size of a joint between them, at the installation positions of panels 3A and 3B at the construction site of the floor slab 1, and a core sheath moving step of moving a core sheath 30 that was previously housed in the sheath 9A toward the sheath 9B in the direction of the pipe axis H, and connecting the sheath 9A and the sheath 9B via the core sheath 30.

Description

Technical Field

[0001] The present invention relates to a sheath connection method and a sheath connection part structure.

Background Art

[0002] Conventionally, as a technology in this field, a concrete segment described in Patent Document 1 below is known. By applying prestress by the post-tensioning method to this concrete segment, a strong joint between the concrete segments is achieved. For this reason, a sheath for inserting PC steel materials is embedded in the concrete segment.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] This type of concrete segment is applied, for example, to the floor slab of a bridge. In this case, the concrete segments may be installed with a gap between them corresponding to the joint, and the joint may be formed by filling this gap with concrete or the like. In this case, the sheaths of the mutual concrete segments need to be continuously connected, and while absorbing construction errors and product manufacturing errors, it is necessary to add a core sheath for connecting the sheaths before filling. However, the work of installing the core sheath to connect the sheaths needs to be carried out within the gap between the segments. For example, it needs to be carried out by, for example, an operator putting his hand into the gap. Therefore, especially when the gap between the segments is small, the workability is not necessarily good, and it may be difficult to install the core sheath efficiently.

[0005] Therefore, the present invention aims to provide a sheath connection method and a sheath connection structure that can efficiently connect sheaths in the gaps between precast panels used to construct a floor slab. [Means for solving the problem]

[0006] The gist of this invention is found in the following [1] to [6].

[0007] [1] A sheath connection method for connecting sheaths for inserting PC steel members between a plurality of precast panels for forming a floor slab, comprising: a panel installation step of installing a first panel having a first sheath and a second panel adjacent to the first panel and having a second sheath, with a gap of the magnitude of a joint between them, at the installation positions of the first and second panels at the construction site of the floor slab; and a core sheath moving step of moving a core sheath that was previously housed in the first sheath toward the second sheath in the pipe axis direction, thereby connecting the first sheath and the second sheath via the core sheath.

[0008] [2] The sheath connection method according to [1], wherein the core sheath, which was previously housed in the first sheath, is engaged with the inner circumferential surface of the first sheath in an engaged state in which rotation around the pipe axis is converted into movement in the direction of the pipe axis, and in the core sheath moving step, the core sheath is moved in the direction of the pipe axis by rotating it around the pipe axis.

[0009] [3] The sheath connection method according to [2], wherein a cord-like material is wrapped around the outer surface of the core sheath that was previously housed in the first sheath, and in the core sheath moving step, the core sheath is rotated around the pipe axis by pulling the cord-like material.

[0010] [4] The sheath connection method according to [3], wherein the cable-like material is spirally wound around the outer surface of the core sheath.

[0011] [5] The sheath connection method according to any one of [1] to [4], wherein a spirally extending recess is formed on the inner circumferential surface of the first sheath, and the core sheath has a tubular portion through which the PC steel material is inserted, and a water-sealing material provided on the outer circumferential surface of the tubular portion and sandwiched between the outer circumferential surface and the inner circumferential surface of the first sheath.

[0012] [6] A sheath connection structure for a precast floor slab panel having a sheath for inserting PC steel members, comprising a core sheath housed within the sheath and interposed in the connection between the sheath and the other sheath, wherein the core sheath is engaged with the inner circumferential surface of the sheath in an engaged state in which rotation around the pipe axis is converted into movement in the direction of the pipe axis, a cable-like material is wrapped around the outer circumferential surface of the core sheath, and the end of the cable-like material is pulled out from the sheath to the outside. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a sheath connection method and a sheath connection structure that can efficiently connect sheaths in the gaps between precast panels that constitute a floor slab. [Brief explanation of the drawing]

[0014] [Figure 1] This is a plan view of the bridge deck to which the sheath connection method and sheath connection structure of this embodiment are applied. [Figure 2] This is a cross-sectional view of the panel. [Figure 3] This is a side view of the core sheath. [Figure 4] This is a close-up cross-sectional view showing the vicinity of the opposing ends of two panels immediately after the panel installation process. [Figure 5] This is a cross-sectional view showing the state immediately after the core sheath movement process. [Figure 6] (a) to (c) are cross-sectional views illustrating the specific steps involved in moving the core sheath. [Figure 7]It is a cross-sectional view showing a state where a caulking material is placed between panels and the joint is completed. [Figure 8] It is a plan view showing a modified example of the floor slab. [Figure 9] It is a plan view showing an enlarged view of the vicinity of the gap G in the floor slab of FIG. 8.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of a sheath connection method and a sheath connection part structure according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of a floor slab 1 of a bridge to which the sheath connection method and the sheath connection part structure of the present embodiment are applied. FIG. 2 is a cross-sectional view of a panel 3 constituting the floor slab 1. The floor slab 1 includes a large number of panels 3 arranged in the bridge axis direction and the direction perpendicular to the bridge axis. Joints 5 and 6 are formed between the panels 3. The joint 5 is a joint between the panels 3 adjacent in the bridge axis direction, and the joint 6 is a joint between the panels 3 adjacent in the direction perpendicular to the bridge axis. An example of the dimensions of the panel 3 is, for example, a length (in the bridge axis direction) of about 2 m, a width (in the direction perpendicular to the bridge axis) of about 5 m, and a thickness of about 150 mm. The width of the joints 5 and 6 is, for example, about 50 mm. The panel 3 is a precast floor slab manufactured in a factory in advance.

[0016] A plurality of panels 3 arranged in the bridge axis direction are firmly joined to each other by applying prestress by the post-tensioning method. Specifically, a sheath 9 extending in the bridge axis direction is embedded in each panel 3, and the PC steel material 7 is continuously inserted into each sheath 9 across a plurality of panels 3. Then, by fixing and tensioning the PC steel material 7 at the panels 3 at both ends, prestress in the bridge axis direction is applied to each panel 3. In FIG. 1, only three PC steel materials 7 are schematically shown for one set of a plurality of panels 3 arranged in the direction perpendicular to the bridge axis, but actually, a larger number of PC steel materials 7 are installed in parallel.

[0017] As described above, in order for the PC steel members 7 to continuously insert each sheath 9 across multiple panels 3, it is necessary that all the sheaths 9 in each panel 3 are continuously connected in the direction of the bridge axis. For this reason, in two adjacent panels 3, 3 in the direction of the bridge axis, the sheaths 9, 9 of each panel must be connected at the joint 5. Below, we will describe the sheath connection method and the structure of the sheath connection part for connecting the sheaths 9, 9 of each panel at the joint 5 between two adjacent panels 3, 3 in the direction of the bridge axis. In the following description, when terms such as "left end / right end" and "left / right" are used, they correspond to the left and right directions in each figure.

[0018] First, the details of the configuration of panel 3 in this embodiment will be described. The sheath connection structure 10 of this embodiment is constructed mainly at the right end of panel 3. As shown in Figure 2, panel 3 comprises a concrete section 4 made of ultra-high-strength fiber-reinforced concrete (UFC) and a sheath 9 embedded in the concrete section 4. By using high-strength UFC, the panel 3 can be made thinner and the deck slab 1 can be made lighter. The sheath 9 is located approximately in the center of the thickness direction of panel 3 and extends in the bridge axis direction over almost the entire length of panel 3. The sheath 9 comprises a sheath body 11, a core receiving pipe 12, and a core housing pipe 13, which are located coaxially with each other. The sheath body 11, the core receiving pipe 12, and the core housing pipe 13 are made of polyethylene spiral sheath pipes, and spirally extending irregularities are formed on the pipe walls of each pipe. These irregularities on the pipe walls ensure good adhesion between the concrete section 4 and the sheath 9. The core receiving pipe 12, the sheath body 11, and the core housing pipe 13 are arranged in this order along the bridge axis. In the figure, the symbol H represents the pipe axis of the sheath 9, and axis H is parallel to the bridge axis. Note that the sheath body 11, the core receiving pipe 12, and the core housing pipe 13 are not limited to being made of polyethylene; they may be steel sheaths or made of other materials.

[0019] The dimension of the neutron storage tube 13 in the bridge axis direction is longer than that of the neutron receiving tube 12. The neutron receiving tube 12 and the neutron storage tube 13 are each composed of a spiral sheath tube with the same diameter. The sheath body 11 is composed of a spiral sheath tube with a slightly smaller diameter than the neutron receiving tube 12 and the neutron storage tube 13. The inner diameter of the spiral sheath tube constituting the neutron receiving tube 12 and the neutron storage tube 13 is, for example, about 55 mm, and the inner diameter of the spiral sheath tube constituting the sheath body 11 is, for example, about 45 mm. The dimension of the neutron receiving tube 12 in the bridge axis direction is, for example, about 90 mm, and the dimension of the neutron storage tube 13 in the bridge axis direction is, for example, about 255 mm.

[0020] The right end of the neutron receiving tube 12 is fitted onto the outer circumference of the left end of the sheath body 11, and the neutron receiving tube 12 and the sheath body 11 are fixed by a vinyl tape 15 wound around the outer circumferential surfaces of the neutron receiving tube 12 and the sheath body 11. Similarly, the left end of the neutron storage tube 13 is fitted onto the outer circumference of the right end of the sheath body 11, and the neutron storage tube 13 and the sheath body 11 are fixed by a vinyl tape 15 wound around the outer circumferential surfaces of the neutron storage tube 13 and the sheath body 11. A waterstop material 17 is sandwiched in the gap between the inner circumferential surface of the right end of the neutron receiving tube 12 and the outer circumferential surface of the left end of the sheath body 11. Similarly, a waterstop material 17 is sandwiched in the gap between the inner circumferential surface of the left end of the neutron storage tube 13 and the outer circumferential surface of the right end of the sheath body 11. The waterstop material 17 is composed of, for example, a water-expandable non-woven fabric wound and adhered multiple times around the outer circumferential surface of the sheath body 11. By this waterstop material 17, the gaps between the sheath body 11 and the neutron receiving tube 12 and between the sheath body 11 and the neutron storage tube 13 are each sealed watertightly.

[0021] The left end of the neutron receiving tube 12 is exposed to the outside from the left end of the panel 3 through the recess 22 at the left end of the panel 3. The right end of the neutron storage tube 13 is exposed to the outside from the right end of the panel 3 through the recess 23 at the right end of the panel 3. With the above configuration, the sheath 9, together with the recesses 22 and 23, forms a through hole 8 penetrating the panel 3 in the bridge axis direction.

[0022] As also shown in Figure 3, the core sheath 30 is housed almost coaxially within the core housing tube 13. The lengths of the core sheath 30 and the core housing tube 13 are set so that the entire length of the core sheath 30 fits almost entirely within the core housing tube 13. In other words, the dimension of the core housing tube 13 in the bridge axis direction is longer than the core sheath 30, allowing the core sheath 30 to be temporarily housed inside the core housing tube 13 in a state where its entire length fits inside. The core sheath 30 comprises a core body 31 (tubular part), a water-sealing material 32 provided on the outer circumferential surface of the left end of the core body 31, and a water-sealing material 33 provided on the outer circumferential surface of the right end of the core body 31. The core body 31 is made of, for example, a polyethylene spiral sheath tube with the same diameter as the sheath body 11, and spirally extending irregularities are formed on the tube wall of the core body 31. The dimensions of the core body 31 in the bridge axis direction are, for example, 216 mm, and the lengths of the portions where the water-stopping materials 32 and 33 are provided are, for example, 40 mm each.

[0023] The waterproofing materials 32 and 33 are, for example, made of a water-swellable nonwoven fabric that is wrapped in multiple layers around and attached to the outer surface of the core body 31. When the core sheath 30 is housed in the core storage tube 13, the waterproofing materials 32 and 33 are compressed to some extent to conform to the uneven shape of the core body 31 and the pipe wall of the core storage tube 13. Since the waterproofing materials 32 and 33 of the core sheath 30 catch to some extent on the unevenness of the pipe wall of the core storage tube 13, the core sheath 30 is held in place so that it does not easily fall out of the core storage tube 13 due to its own weight or the like.

[0024] Furthermore, a cord 35 (rope-like material) is wrapped around the outer surface of the core sheath 30. The cord 35 is wound spirally along approximately the entire length of the core sheath 30. For example, in the example shown in Figure 3, the cord 35 is wound so that it fits into and is guided by the spiral recess of the core body 31. This configuration makes it easier to wrap the cord 35 spirally around the core body 31. One end of the cord 35 is fastened to the left end of the core sheath 30 (for example, the left end of the core body 31), and the other end of the cord 35 extends from near the right end of the core sheath 30. When the core sheath 30 is housed in the core storage tube 13, the other end of the cord 35 is pulled out from the core storage tube 13 and temporarily secured to the top surface of the panel 3 with, for example, tape. By using a cord 35 in a color that is easily visible at night, work efficiency during nighttime construction is improved. In addition, thread, wire, or the like may be used instead of string 35, and the material of string, thread, wire, etc. is not particularly limited.

[0025] The sheath connection method of this embodiment is performed when constructing the deck slab 1 (Figure 1) using the panel 3, and comprises the panel installation process and the core sheath movement process, which will be described below. Figure 4 is an enlarged cross-sectional view showing the vicinity of the opposing ends of two adjacent panels 3,3 in the bridge axis direction, and shows the state immediately after the panel installation process. In the following, when distinguishing between the two panels 3,3, the panel 3 on the left in Figure 4 will be called "panel 3A," and the panel 3 on the right will be called "panel 3B." Furthermore, the sheath 9, sheath body 11, core receiving tube 12, and core housing tube 13 of panel 3A shall be referred to as "sheath 9A," "sheath body 11A," "core receiving tube 12A," and "core housing tube 13A," respectively, and the sheath 9, sheath body 11, core receiving tube 12, and core housing tube 13 of panel 3B shall be referred to as "sheath 9B," "sheath body 11B," "core receiving tube 12B," and "core housing tube 13B," respectively.

[0026] [Panel installation process] In the panel installation process, as shown in Figure 4, panels 3A and 3B are installed at their respective installation positions at the construction site of the floor slab 1. At this time, a gap G equal to the width of the joint 5 is left between panels 3A and 3B. Inside the core storage tube 13A of panel 3A, the core sheath 30, with the string 35 wound around it, is pre-installed and stored before this panel installation process. Note that the process of installing the core sheath 30 inside the core storage tube 13A as described above may be performed at the factory during the manufacturing of panel 3, or it may be performed at the construction site of the floor slab 1 (Figure 1) before the panel installation process. In the process of installing the core sheath 30, as shown in Figure 3, the core sheath 30 may be pushed linearly in the direction of axis H into the core storage tube 13A, or the core sheath 30 may be inserted into the core storage tube 13A while rotating around axis H. In this way, when the panel installation process is executed, the core sheath 30 is temporarily stored inside the core storage tube 13 of panel 3. Therefore, when installing panel 3 at the installation location, interference between the core sheath 30 and other adjacent panels 3 that have already been installed can be avoided.

[0027] [Core sheath movement process] In the core sheath movement process, the core sheath 30, which was previously installed inside the core housing tube 13A, is moved in the axial direction H toward the core receiving tube 12B of panel 3B. As a result, the core housing tube 13A and the core receiving tube 12B are connected via the core sheath 30, as shown in Figure 5. Figure 5 is a cross-sectional view showing the state immediately after the core sheath movement process.

[0028] The specific procedure for moving the core sheath 30 as described above is as follows. Figures 6(a) to 6(c) are cross-sectional views illustrating this specific procedure. In Figure 6, to avoid making the diagram too complex, detailed depictions are omitted, and the cross-sections of panels 3A and 3B are schematically shown. As shown in Figure 6(a), the worker detaches the end of the string 35 that is temporarily fixed to the upper surface of panel 3A, and as shown in Figure 6(b), pulls the string 35 upward. As a result, the core sheath 30, around which the string 35 is wrapped, rotates around its own axis (around axis H) within the core storage tube 13A. A loop 35a is formed at the end of the string 35 to facilitate the worker's pulling operation.

[0029] Here, the waterproofing material 32 (Figure 3) of the core sheath 30 is sandwiched in the gap between the core body 31 and the core storage tube 13A to provide waterproofing. Therefore, the inner surface of the core storage tube 13A, which has a spiral-shaped uneven surface, is somewhat embedded in the outer surface of the waterproofing material 32. Similarly, the inner surface of the core storage tube 13A is also somewhat embedded in the outer surface of the waterproofing material 33 (Figure 3). In other words, there is a spirally extending recess 14 (Figure 2) on the inner surface of the core storage tube 13A, and it can be said that a part of the outer surfaces of the waterproofing materials 32 and 33 is raised so as to fit into the recess 14. Given this contact state between the inner surface of the core storage tube 13A and the outer surfaces of the waterproofing materials 32 and 33, it can be said that the core storage tube 13A and the waterproofing materials 32 and 33 function to some extent like female and male threads, albeit imperfectly, and are screwed together. Therefore, it can be said that the core sheath 30 housed in the core housing tube 13A is engaged with the inner circumferential surface of the core housing tube 13A in such an engagement state that rotation around its own axis (rotation around axis H) is converted into movement in the direction of axis H.

[0030] As a result of this engagement, as shown in Figure 6(b), the string 35 is pulled and the core sheath 30 rotates around its axis, causing the core sheath 30 to move in the direction of axis H toward the panel 3B while rotating, and gradually disengaging from the core storage tube 13A. Then, as shown in Figure 6(c), when the right end of the core sheath 30 reaches the core receiving tube 12B, the water-sealing material 33, which functions like a male thread, is screwed into the core receiving tube 12B, which functions like a female thread, thereby connecting the two. Then, as shown in Figure 5, when the right end face of the core body 31 abuts against the left end face of the sheath body 11B of the panel 3B, the movement of the core sheath 30 is completed. The pulled-out string 35 can be cut at the appropriate position. In this way, as shown in Figure 5, the core storage tube 13A and the core receiving tube 12B are connected via the core sheath 30, and the core sheath movement process is completed.

[0031] As shown in Figure 5, the dimensions of the core sheath 30 in the bridge axis direction are designed so that both ends of the core sheath 30 are inserted into the core storage tube 13A and the core receiving tube 12B, respectively, and the core sheath 30 is interposed in the connection between the two. Furthermore, as mentioned above, the female / male thread function of the core storage tube 13A and the waterproofing materials 32 and 33 is not perfect. Therefore, when the core sheath 30 is rotated by pulling the string 35, the core sheath 30 does not necessarily move in the axis H direction by a distance equivalent to the rotation, for example, by spinning freely. Accordingly, it is preferable that the length of the string 35 that is pre-wound around the core sheath 30 is made to be longer than the required movement distance of the core sheath 30. Also, naturally, the winding direction, number of turns, spiral pitch, length, etc. of the string 35 wound around the core sheath 30 are appropriately determined based on the relationship between the rotation of the core sheath 30 around axis H and the movement in the axis H direction.

[0032] After the core sheath movement process is completed, as shown in Figure 7, a filler material 40 is poured into the gap G between panel 3A and panel 3B to embed the core sheath 30, completing the joint 5. The filler material 40 may be, for example, a super-high performance fiber-reinforced cement composite material (UHPFRC). Subsequently, PC steel members 7 (Figure 1) are inserted through the through-holes 8 of the sheath 9, which are continuously connected in the bridge axis direction across multiple panels 3, and tensioned. By applying prestress in this post-tensioning manner, multiple panels 3 aligned in the bridge axis direction are firmly joined to each other.

[0033] The sheath connection structure 10 of this embodiment, which enables the sheath connection method described above, is a sheath connection structure for connecting a sheath 9B of another panel 3B in a precast floor slab panel 3A having a sheath 9A through which a PC steel material 7 is inserted. This sheath connection structure 10 is housed within the sheath 9A and includes a core sheath 30 for intervening in the connection between the sheath 9A and the other sheath 9B. The core sheath 30 is engaged with the inner circumferential surface of the sheath 9A in an engaged state in which rotation around axis H is converted into movement in the direction of axis H. A string 35 is wrapped around the outer circumferential surface of the core sheath 30, and the end of the string 35 is pulled out from the sheath 9A to the outside.

[0034] The effects and benefits of the sheath connection method and sheath connection structure of this embodiment, as described above, will now be explained.

[0035] In the sheath connection method and sheath connection structure of this embodiment, adjacent panels 3A (first panel) and 3B (second panel) are installed at the installation positions of panels 3A and 3B at the construction site of the floor slab 1, with a gap G equal to the joint 5 between them (panel installation process). Subsequently, the core sheath 30, which was pre-installed inside the sheath 9A (first sheath), is moved in the axial direction H toward the sheath 9B (second sheath), and the sheaths 9A and 9B are connected via the core sheath 30 (core sheath movement process).

[0036] Here, since the core sheath 30 is longer than the distance between the sheaths 9A and 9B, it is not easy to bring the core sheath 30 into the gap G from the outside and attach both ends to the sheaths 9A and 9B. In contrast, with the above configuration of this embodiment, the core sheath 30, which is already inside the sheath 9A, can be pulled out in the direction of axis H and moved in the direction of axis H. Therefore, the work is simplified compared to inserting the core sheath 30 into the gap G from the outside or performing the attachment operation of the core sheath 30 inside the gap G. Consequently, the sheaths 9A and 9B can be efficiently connected in the gap G between the panels 3A and 3B, and the work time can be shortened. Furthermore, since the work is simplified as described above, the gap G required for the work can be designed to be narrower. This reduces the amount of filler material 40 required and the effort involved in the filler work.

[0037] Furthermore, in the sheath connection method and sheath connection structure of this embodiment, the core sheath 30 inside the sheath 9A is engaged with the inner circumferential surface of the sheath 9A in an engaged state in which rotation around axis H is converted into movement in the direction of axis H. In the core sheath movement process, the core sheath 30 can be rotated around axis H to achieve the aforementioned movement in the direction of axis H. In other words, movement of the core sheath 30 in the direction of axis H can be achieved by a relatively simple operation such as rotating the core sheath 30. Therefore, the operation is simplified compared to, for example, an operation to extend the core sheath 30 in the direction of axis H. Also, the operation of rotating the core sheath 30 is easier to perform even when the gap G is narrow, compared to an operation to extend it in the direction of axis H.

[0038] Furthermore, in the sheath connection method and sheath connection structure of this embodiment, a string 35 is wrapped around the outer surface of the core sheath 30 inside the sheath 9A, and in the core sheath movement process, the core sheath is rotated around the axis H by pulling the string 35. With this configuration, instead of inserting hands or tools into the gap G, the worker can perform a simple operation such as pulling the string 35 from outside the gap G. Therefore, work efficiency is improved and working time can be shortened. In addition, since there is less need to consider inserting the worker's hands or tools into the gap G, the gap G can be designed to be narrower, and the required amount of gap-filling material 40 and the effort of gap-filling work are reduced.

[0039] Furthermore, the string 35 is spirally wound around the outer surface of the core sheath 30. With this configuration, while the core sheath 30 is moving in the axis H direction due to the pulling operation of the string 35, the position where the string 35 unravels from the core sheath 30 does not change significantly in the axis H direction, so the operator does not need to significantly change the position or direction in which they pull the string 35. In order to efficiently obtain this effect, it is preferable that the spiral pitch of the wound string 35 and the spiral pitch of the irregularities of the core housing tube 13A are close, and it is even preferable that they are the same. If the string 35 is wound so as to be guided into the spiral recess on the outer surface of the core body 31 as shown in Figure 3, it is preferable that the spiral pitch of the irregularities of the core body 31 and the spiral pitch of the irregularities of the core housing tube 13A are close, and it is even preferable that they are the same.

[0040] Furthermore, in the sheath connection method and sheath connection structure of this embodiment, a spirally extending recess 14 is formed on the inner circumferential surface of the sheath 9A, and the core sheath 30 has a core body 31 (tubular portion) through which the PC steel material is inserted, and water-sealing materials 32 and 33 provided on the outer circumferential surface of the core body 31 and sandwiched between the outer circumferential surface and the inner circumferential surface of the sheath 9A. With this configuration, as described above, the inner circumferential surface of the core housing pipe 13A having the recess 14 bites into the outer circumferential surface of the water-sealing materials 32 and 33 to a certain extent, thereby achieving an engagement state in which the rotation of the core sheath 30 around the axis H is converted into movement in the direction of axis H.

[0041] The present invention can be implemented in various forms, including the embodiments described above, by making various changes and improvements based on the knowledge of those skilled in the art. Furthermore, it is possible to construct modified versions by utilizing the technical matters described in the embodiments described above. The configurations of each embodiment may also be used in appropriate combinations.

[0042] In the embodiments described, the case in which the deck slab 1 (Figure 1) and panel 3 are rectangular in plan view was used as an example. However, the present invention is also applicable when the deck slab 1 and panel 3 are parallelograms, for example, as shown in Figure 8. In this case, as shown in the plan view of Figure 9, the gap G between the panels 3 extends diagonally with respect to the bridge axis direction, and the core sheath 30 crosses the gap G diagonally. Therefore, compared to the deck slab 1 and panel 3 in Figure 1, it is even more difficult to insert the core sheath 30 into the gap G from the outside or to install the core sheath 30 inside the gap G. Thus, when the deck slab 1 and panel 3 are parallelograms, as shown in Figure 8, the present invention is particularly suitable for avoiding the above-mentioned operations.

[0043] Furthermore, given the positional relationship between the gap G and the core sheath 30 as shown in Figure 8, it is not easy to perform tasks such as inserting a tool like a pipe wrench from outside the gap G to grasp the core sheath 30 and rotating the tool around axis H to rotate the core sheath 30. In other words, because the gap G extends diagonally with respect to the rotation axis direction (axis H direction) of the core sheath 30, the tool used to rotate it is likely to interfere with the concrete portion 4 of the panel 3. Consequently, the range of rotation of the tool becomes small, resulting in inefficient rotation. In contrast, the aforementioned method of pulling a string 35 pre-wrapped around the core sheath 30 allows the core sheath 30 to be rotated efficiently, almost independently of the direction in which the gap G extends. Therefore, when the floor slab 1 and panel 3 are parallelograms as shown in Figure 8, the aforementioned method of pulling a string 35 pre-wrapped around the core sheath 30 is particularly suitable for application.

[0044] Furthermore, in the deck slab 1, multiple panels 3 arranged perpendicular to the bridge axis may be firmly joined to each other by applying prestress using a post-tensioning method. In this case, the same sheath connection method and sheath connection structure as for joint 5 may be applied to the sheath connection method and sheath connection structure in joint 6 (Figures 1 and 8). [Explanation of Symbols]

[0045] 1...Floor slab, 3,3A,3B...Panel, 5,6...Joint, 7...PC steel, 9,9A,9B...Sheath, 7...PC steel, 10...Sheath connection structure, 14...Recess, 30...Core sheath, 31...Core body (tubular part), 32,33...Waterproofing material, 35...String (rope-like material), H...Pipe axis.

Claims

1. A sheath connection method for connecting sheaths for inserting PC steel members between multiple precast panels that constitute a floor slab, A panel installation process involves installing a first panel having a first sheath and a second panel adjacent to the first panel and having a second sheath, with a gap of the length of a joint between them, at the respective installation positions of the first and second panels at the construction site of the floor slab. A sheath connection method comprising: a core sheath moving step of moving a core sheath, which was previously housed in the first sheath, toward the second sheath in the axial direction of the pipe, thereby connecting the first sheath and the second sheath via the core sheath.

2. The core sheath, which was previously housed within the first sheath, is engaged with the inner circumferential surface of the first sheath in an engaged state in which rotation around the pipe axis is converted into movement in the direction of the pipe axis. The sheath connection method according to claim 1, wherein in the core sheath moving step, the core sheath is moved in the direction of the pipe axis by rotating it around the pipe axis.

3. A cable-like material is wrapped around the outer surface of the core sheath that was previously housed within the first sheath. The sheath connection method according to claim 2, wherein in the core sheath movement step, the core sheath is rotated around the pipe axis by pulling the cable-like material.

4. The sheath connection method according to claim 3, wherein the cable-like material is spirally wound around the outer surface of the core sheath.

5. A spirally extending recess is formed on the inner circumferential surface of the first sheath. The sheath connection method according to any one of claims 1 to 4, wherein the core sheath has a tubular portion through which the PC steel material is inserted, and a water-sealing material provided on the outer surface of the tubular portion and sandwiched between the outer surface and the inner surface of the first sheath.

6. A sheath connection structure for a precast floor slab panel having a sheath for inserting PC steel members, wherein the sheath connection is for connecting to other sheaths of other panels, The sheath is housed within the aforementioned sheath and comprises a core sheath for interposing in the connection between the aforementioned sheath and the other sheaths, The core sheath is engaged with the inner circumferential surface of the sheath in an engaged state in which rotation around the pipe axis is converted into movement in the direction of the pipe axis, A sheath connection structure in which a cable-like material is wrapped around the outer surface of the core sheath, and the end of the cable-like material is pulled out from the sheath to the outside.

Images