Internal scaffolding installation structure

Abstract

To provide an attachment structure of an inner scaffolding capable of improving workability for detachment of the inner scaffold.SOLUTION: An attachment structure of an inner scaffolding according to the present invention is configured to advance a shaft part 25 of a projected part 23 arranged on the inner scaffold 2 so as to be engaged with a step part 14 of an engaged part 13 arranged inside of a caisson skeleton 1, and then to attach the inner scaffold 2 on the caisson skeleton 1. This allows the inner scaffold 2 to be directly attached on the caisson scaffold 1 so that attachment work of the inner scaffold 2 on the caisson skeleton 1 can be easily performed.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an attachment structure for an inner scaffolding used for press-in installation of a split-assembly type earth retaining wall (caisson). [Background technology]

[0002] A known conventional mounting structure for an internal scaffold is, for example, that described in Patent Document 1 below.

[0003] To give an overview, in the mounting structure for the internal scaffolding described in Patent Document 1, a bracket is attached to the inside of the caisson body after press-fitting using anchor bolts, and the internal scaffolding is installed on the top surface of this bracket.

[0004] Specifically, a bracket installation scaffold is installed inside the caisson body after press-fitting, and workers climb onto the installed bracket installation scaffold and install the bracket inside the caisson body using multiple anchor bolts. After that, the inner scaffold is lifted by a crane and hoisted inside the caisson body, and then lowered and placed on the bracket, completing the installation of the inner scaffold on the caisson body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-189267 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional internal scaffolding mounting structure, the internal scaffolding is installed on the caisson body via the bracket. Therefore, to install the internal scaffolding, it is necessary to first install the bracket mounting scaffolding to attach the internal scaffolding to the caisson body, then use this bracket mounting scaffolding to attach the bracket to the caisson body, and then remove the bracket mounting scaffolding. This makes the internal scaffolding installation work complicated, and there is room for improvement.

[0007] Furthermore, because the conventional mounting structure for the internal scaffolding is a structure in which the internal scaffolding is installed via the bracket, when removing the internal scaffolding after the caisson body is assembled, it is necessary to first lift and remove the internal scaffolding with a crane, then install the bracket mounting scaffolding, use this bracket mounting scaffolding to remove the bracket from the caisson body, and then remove the bracket mounting scaffolding, repeating these steps. This makes not only the installation work of the internal scaffolding but also the removal work of the internal scaffolding cumbersome, and there has been a demand for a mounting structure for the internal scaffolding that allows the internal scaffolding to be easily attached and detached.

[0008] The present invention was devised with an eye on such technical issues, and aims to provide an inner scaffolding mounting structure that can improve the workability involved in attaching and detaching the inner scaffolding. [Means for solving the problem]

[0009] In one aspect, the mounting structure for an internal scaffolding of the present invention is an internal scaffolding mounting structure that can be raised and lowered vertically by a crane and can be attached to the inside of a caisson body in a self-supporting manner, and is characterized in that it comprises an engaging portion that is recessed or stepped and provided on the inside of the caisson body, and a protrusion that is provided on the internal scaffolding so that it can freely move in and out in a radial direction perpendicular to the vertical direction and that engages with the engaging portion.

[0010] In this way, according to the present invention, the inner scaffolding can be attached to the caisson body by extending the protrusions provided on the inner scaffolding in the radial direction and engaging them with the engaging parts provided on the inside of the caisson body. This makes it possible to attach the inner scaffolding directly to the caisson body, compared to the conventional inner scaffolding attachment structure that requires brackets to be attached to the caisson body in advance, making it easier to attach the inner scaffolding to the caisson body.

[0011] Furthermore, according to the present invention, when removing the inner scaffolding, the inner scaffolding can be detached from the caisson body simply by retracting the protrusion to release the engagement of the protrusion with the engaged portion.

[0012] In addition, as another aspect of the mounting structure of the inner scaffolding, it is desirable that the protrusion portion has a plurality of bearing portions provided along the radial direction on the upper surface of the inner scaffolding, a shaft portion that is supported by the bearing portions so as to be able to slide in the radial direction and engages with the engaged portion while protruding outward from the outer peripheral edge of the inner scaffolding, and a stopper portion that is provided integrally with or separately from the shaft portion and engages with the bearing portions to restrict the sliding of the shaft portion.

[0013] According to this aspect, the stopper portion is engaged with the bearing portion, thereby restricting the sliding of the shaft portion. By mechanically restricting the sliding of the shaft portion with the stopper portion, it is possible to reliably prevent the shaft portion from unintentionally retracting and falling off the engaged portion when the internal scaffolding is attached to the caisson body, thereby improving the safety of the installation of the internal scaffolding.

[0014] In yet another aspect of the mounting structure for the internal scaffolding, the shaft portion is arranged to be freely rotatable around the axis of the shaft portion when supported by the bearing portion, and at least one of the multiple bearing portions has an open groove formed to communicate the inside and outside of the bearing portion at a specific phase in the rotational direction of the shaft portion and to allow the stopper portion to pass through, and the stopper portion is arranged integrally with the shaft portion, and allows the shaft portion to slide by passing through the open groove at the specific phase, and restricts the sliding of the shaft portion by engaging with the bearing portion at other phases except for the specific phase.

[0015] According to this aspect, the locking state of the stopper part with respect to the bearing part can be released by rotating the shaft part and aligning the stopper part with a specific phase. This eliminates the risk of the locking state of the stopper part with respect to the bearing part being unintentionally released, and more effectively improves the installation safety of the internal scaffolding.

[0016] In addition, as yet another aspect of the mounting structure for the inner scaffolding, it is desirable that the mounting structure comprises a fixed portion provided on the upper surface of the inner scaffolding at a position more inward than the bearing portion in the radial direction, and an expandable elastic member having one end fixed to the fixed portion and the other end hooked to the stopper portion, and which exerts a contraction force when the shaft portion protrudes from the inner scaffolding, and that when the inner scaffolding is removed, the elastic member exerts the contraction force when the other end is hooked to the stopper portion, causing the shaft portion to retract until the tip of the shaft portion is positioned more inward than the outer edge of the inner scaffolding.

[0017] According to this aspect, when the inner scaffolding is removed, the shaft can be automatically retracted by the contraction force of the elastic member. This makes it possible to omit the work of releasing the engagement of the protrusion with the engaged part, which is performed by retracting the shaft when removing the inner scaffolding, making it even easier to remove the inner scaffolding.

[0018] Furthermore, as yet another aspect of the mounting structure of the inner scaffolding, it is desirable that the contraction force of the elastic member be set to be smaller than the friction force acting between the engaging portion and the shaft portion, and when the inner scaffolding is lifted by the crane and the shaft portion is separated from the engaging portion in the vertical direction, the contraction force causes the shaft portion to retract until the tip of the shaft portion is positioned inside the outer edge of the inner scaffolding.

[0019] According to this aspect, the shaft does not slide due to the contraction force of the elastic member when friction between the shaft and the locked portion is acting, but retracts due to the contraction force of the elastic member when the friction between the shaft and the locked portion is released. As a result, the shaft remains locked to the locked portion due to the friction between the shaft and the locked portion before the inner scaffolding is lifted, which not only makes it possible to remove the inner scaffolding more safely, but also makes it possible to retract the shaft with a relatively small contraction force, allowing the use of an elastic member with a relatively small elasticity and facilitating the installation work of the elastic member that hooks the elastic member to the stopper portion against the elastic force of the elastic member. As a result, the removal work of the inner scaffolding can be made even easier.

[0020] Furthermore, as yet another aspect of the mounting structure of the internal scaffolding, it is desirable that the shaft portion has an insertion hole that opens in the radial direction, and the stopper portion is composed of a locking member that is separate from the shaft portion and is detachably attached to the insertion hole, so that the locking member allows the shaft portion to slide when it is detached from the insertion hole, and the locking member locks onto the bearing portion when it is inserted into the insertion hole to restrict the sliding of the shaft portion.

[0021] According to this aspect, the locking member provided separately from the shaft is disengaged from the insertion hole to allow the shaft to slide, and when the locking member is inserted into the insertion hole, it is locked to the bearing portion to restrict the sliding of the shaft. In other words, when the locking member is inserted into the insertion hole, sliding of the shaft can be restricted regardless of the phase of the shaft. This eliminates the risk of the locking state of the stopper portion relative to the bearing portion being unintentionally released, and more effectively improves the safety of the internal scaffolding installation.

[0022] Furthermore, according to this aspect, the sliding of the shaft portion can be restricted simply by inserting the locking member into the insertion hole, which has the advantage that the sliding of the shaft portion can be restricted without performing any special operation, such as rotating the shaft portion to align it with a specific phase.

[0023] Furthermore, as yet another aspect of the mounting structure for the inner scaffolding, there is provided a lever portion provided integrally with the shaft portion, a fixed portion provided on the upper surface of the inner scaffolding at a position more inward than the bearing portion in the radial direction, and an expandable elastic member having one end fixed to the fixed portion and the other end hooked to the lever portion, and which exerts a contraction force when the shaft portion protrudes from the inner scaffolding, wherein the bearing portion supports the shaft portion by means of an elongated shaft hole extending in the vertical direction, and the shaft hole has widening portions on both sides of the lower end in the vertical direction that expand the shaft hole in a direction perpendicular to the vertical direction to allow the stopper portion to pass through, and when the shaft portion is engaged with the engaged portion, the shaft portion is positioned above the shaft hole in the vertical direction, When the stopper portion engages with the end face of the bearing portion, while the shaft portion is separated from the engaged portion, the shaft portion is positioned below the shaft hole in the vertical direction, allowing the stopper portion to pass through the widening portion, and when the inner scaffolding is removed, the other end of the elastic member is hooked onto the lever portion with the stopper portion engaged with the end face of the bearing portion, and when the inner scaffolding is lifted by the crane, the stopper portion moves below the shaft hole due to its own weight, and the widening portion exerts the contraction force, causing the shaft portion to retract until the tip of the shaft portion is positioned inside the outer edge of the inner scaffolding.

[0024] According to this aspect, when the inner scaffolding is removed, the shaft can be automatically retracted by the contraction force of the elastic member. This makes it possible to omit the work of releasing the engagement of the protrusion with the engaged part, which is performed by retracting the shaft when removing the inner scaffolding, making it even easier to remove the inner scaffolding.

[0025] According to the above aspect, when the shaft is engaged with the engaging portion, the shaft is positioned above the shaft hole and the stopper engages with the end face of the bearing portion, and when the shaft is separated from the engaging portion, the shaft is positioned below the shaft hole and allows the stopper to pass through the widened portion. Therefore, without attaching or detaching the stopper, when the shaft is engaged with the engaging portion and sliding restriction of the shaft is required, the stopper restricts sliding of the shaft, and when the shaft is separated from the engaging portion and sliding restriction of the shaft is not required, sliding of the shaft is permitted. In this way, the ability to automatically restrict or release sliding of the shaft as needed makes it even easier to attach and detach the internal scaffolding.

[0026] In particular, by combining the mechanism for automating the restriction of the sliding of the shaft with the mechanism for automating the storage of the shaft using the elastic member, these two mechanisms are organically linked, and when removing the inner scaffolding, simply by hooking the elastic member onto the lever, the locking state by the locking member can be released and the shaft can be stored automatically using the elastic member. This significantly reduces the amount of work required for removing the inner scaffolding, making the removal of the inner scaffolding even easier.

[0027] In yet another aspect of the mounting structure of the inner scaffolding, the inner scaffolding has a receiving groove cut out in the outer peripheral edge portion, the receiving groove being provided on the inside in the radial direction and having a bottomed portion whose vertical lower end is closed by a bottom wall, and being provided on the outside in the radial direction and having an open portion penetrating in the vertical direction, the protrusion portion is generally linear, and is provided so that its middle portion is supported by the open portion of the receiving groove and can rotate around the middle portion as a fulcrum, and is displaced between a horizontal phase that is generally parallel to the horizontal direction and a vertical phase that is generally parallel to the vertical direction, and in the horizontal phase It is desirable that one end portion facing inward in the radial direction abuts the upper surface of the bottom wall, restricting the rotation of the protrusion portion, and the other end portion facing outward in the radial direction protrudes outward from the outer peripheral edge of the inner scaffolding and engages with the engaging portion, thereby holding the inner scaffolding in a self-supporting state, while in the vertical phase, both ends of the protrusion portion at the open portion are oriented in the vertical direction of the inner scaffolding, and both ends of the protrusion portion are located inside the outer peripheral edge of the inner scaffolding in the radial direction, thereby allowing the inner scaffolding to rise and fall.

[0028] According to this aspect, simply by changing the rotational phase of the protrusion, it is possible to switch between the state of engagement of the protrusion with the locked portion and the state of release of the engagement. This makes it relatively easy to switch the state of engagement of the protrusion with the locked portion compared to an aspect in which the shaft is slid to switch the state of engagement of the protrusion with the locked portion, and makes it even easier and more efficient to attach and detach the internal scaffolding to the caisson body.

[0029] Furthermore, as yet another aspect of the mounting structure of the inner scaffolding, when the inner scaffolding is mounted, it is desirable that when the protrusion portion protrudes outward from the outer peripheral edge of the inner scaffolding and is in an inclined phase between the horizontal phase and the vertical phase, as the inner scaffolding moves downward, the other end portion abuts against the engaged portion, causing the one end portion to rotate in a direction approaching the bottom wall and automatically displace to the horizontal phase.

[0030] According to this aspect, when installing the inner scaffolding, simply lowering the inner scaffolding causes the protrusion, which is in the inclined phase, to abut against the locked part, thereby automatically rotating and displacing the protrusion to the horizontal phase. As a result, even if the protrusion is not in a completely horizontal phase beforehand when installing the inner scaffolding, the protrusion can be automatically displaced to the horizontal phase, ensuring the locking state between the protrusion and the locked part, making the installation work of the inner scaffolding even easier.

[0031] Furthermore, as another aspect of the mounting structure of the inner scaffolding, when the inner scaffolding is removed, it is desirable that the other end of the protrusion, which protrudes outward from the outer edge of the inner scaffolding as the inner scaffolding moves upward, abuts against the caisson body stacked vertically above the inner scaffolding, causing the one end to rotate in a direction away from the bottom wall and automatically displace to the vertical phase.

[0032] According to this aspect, when removing the inner scaffolding, simply by raising the inner scaffolding, the protrusions in the horizontal phase will abut against the upper caisson body, automatically rotating and displacing the protrusions into the vertical phase. As a result, when removing the inner scaffolding, the protrusions can be automatically stored in the inner scaffolding without the worker having to do anything to the protrusions, making the removal of the inner scaffolding even easier. [Effects of the Invention]

[0033] According to the present invention, the inner scaffolding can be attached to the caisson body by extending the protrusions provided on the inner scaffolding in the radial direction and engaging with the engaging parts provided on the inside of the caisson body. Therefore, compared to the conventional inner scaffolding attachment structure that requires brackets to be attached to the caisson body in advance to place the inner scaffolding, it is possible to attach the inner scaffolding directly to the caisson body. As a result, the attachment work of the inner scaffolding to the caisson body is simplified, and the attachment work of the inner scaffolding can be easily performed.

[0034] Furthermore, according to the present invention, when removing the inner scaffolding, it is possible to detach the inner scaffolding from the caisson body simply by retracting the protruding portion to release the protruding portion from the locked portion. Therefore, not only the installation work but also the removal work of the inner scaffolding can be easily performed. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 is a perspective view showing the installation state of the inner scaffolding according to the first embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of the inner scaffolding shown in FIG. 1. [Figure 3] FIG. 3 is a plan view of the inner scaffolding shown in FIG. 2, showing the state in which the protrusions are protruded. [Figure 4] FIG. 3 is a plan view of the inner scaffolding shown in FIG. 2, showing a state in which the protrusions are stored. [Figure 5] 1A and 1B are diagrams showing the installation state of the internal scaffolding according to the first embodiment of the present invention, in which (a) is a plan view and (b) is a cross-sectional view taken along line AA in FIG. 1A. [Figure 6] 1 is a cross-sectional view showing a method of installing an internal scaffolding according to a first embodiment of the present invention. FIG. [Figure 7] 1 is a cross-sectional view showing a method for removing an inner scaffolding according to a first embodiment of the present invention. FIG. [Figure 8] This is an enlarged plan view showing the main parts of the internal scaffolding according to the second embodiment of the present invention. [Figure 9] FIG. 9 is a cross-sectional view taken along line BB in FIG. 8. [Figure 10] 10 is a cross-sectional view showing a method for removing an inner scaffolding according to a second embodiment of the present invention. FIG. [Figure 11] 10A and 10B are enlarged views of the main parts of the internal scaffolding according to the third embodiment of the present invention, showing the protruding portion in a protruding state, with (a) being a perspective view and (b) being a plan view. [Figure 12] 10A and 10B are enlarged views of the main parts of the internal scaffolding according to the third embodiment of the present invention, showing the state in which the protrusions are stored, with (a) being a perspective view and (b) being a plan view. [Figure 13]This is an enlarged view of the main part of the inner scaffolding according to the fourth embodiment of the present invention, showing the protruding portion, where (a) is a cross-sectional view of the inner scaffolding, and (b) is a cross-sectional view taken along line CC of the same figure (a). [Figure 14] 10A and 10B are enlarged views of the main parts of the inner scaffolding according to the fourth embodiment of the present invention, showing the state in which the protrusions are stored, where (a) is a cross-sectional view of the inner scaffolding and (b) is a cross-sectional view along line DD in FIG. 10A. [Figure 15] This is an oblique view showing an enlarged view of the main parts of the inner scaffolding according to the fifth embodiment of the present invention, showing the state in which the protrusions are protruded. [Figure 16] FIG. 10 is an enlarged perspective view of the main parts of the inner scaffolding according to the fifth embodiment of the present invention, showing the state in which the protrusions are stored. [Figure 17] 10A and 10B are diagrams showing the installation state of an internal scaffolding according to a fifth embodiment of the present invention, in which (a) is a plan view and (b) is a cross-sectional view taken along the line EE in FIG. [Figure 18] A cross-sectional view showing a method of installing an inner scaffolding according to a fifth embodiment of the present invention. [Figure 19] 10 is a cross-sectional view showing a method for removing an inner scaffolding according to a fifth embodiment of the present invention. FIG. [Figure 20] FIG. 10 is a perspective view showing the installation state of an inner scaffolding according to a modified example of the present invention. [Figure 21] FIG. 1 is a cross-sectional view showing a conventional method for installing an internal scaffolding. [Figure 22] FIG. 1 is a cross-sectional view showing a conventional method for removing inner scaffolding. DETAILED DESCRIPTION OF THE INVENTION

[0036] Hereinafter, embodiments of the mounting structure for internal scaffolding according to the present invention will be described in detail with reference to the drawings. Note that in each of the following embodiments, the present invention will be exemplified as being applied to the press-in installation of a caisson body as a submerged earth retaining wall made of assembled RC segments. In the following explanation, the direction perpendicular to the press-in direction of the caisson body 1 will be referred to as the "radial direction," and the direction around the press-in direction of the caisson body 1 will be referred to as the "circumferential direction."

[0037] [First embodiment] 1 to 7 show an attachment structure for an inner scaffolding according to a first embodiment of the present invention. For convenience, the following description will be divided into sections on the attachment structure for the inner scaffolding, the method for attaching and detaching the inner scaffolding, and the effects of this embodiment.

[0038] (Inner scaffolding mounting structure) As shown in Figure 1, in the open caisson method, a generally cylindrical caisson body 1, which is a cylindrical, segmented, assembled earth retaining wall, is pressed into a vertical shaft drilled in the ground G and sunk. The caisson body 1 is made up of a plurality of ring pieces 11 connected in the horizontal and vertical directions and formed by dividing the caisson body 1 into roughly arc-shaped pieces (five pieces in this embodiment). The caisson body 1 is formed by assembling generally cylindrical unit earth retaining walls 10, each made up of ring pieces 11 connected in the circumferential direction, in a vertical stack on a cutting edge ring 12 installed at the bottom of the pit.

[0039] At this time, the ring pieces 11 that make up this unit earth-retaining wall 10 are fastened together with bolts and nuts (not shown) using joint plates or the like (not shown). The work of connecting (fastening) each ring piece 11 is carried out by workers standing on the inner scaffolding 2 installed inside the caisson body 1. In this way, the caisson body 1 is assembled by changing the inner scaffolding 2 vertically upward at predetermined intervals according to the height of the unit earth-retaining walls 10, for example, every three layers of unit earth-retaining walls 10.

[0040] The inner scaffolding 2 has a plate-shaped base member 21 attached to the inside of the caisson body 1, and a scaffolding member 22 (see, for example, Figure 6) fixed onto this base member 21. The base member 21 is formed in a shape corresponding to the internal space of the caisson body 1, and in this embodiment, in the shape of a disk that is roughly circular in plan view. The base member 21 has a plurality of protrusions 23 arranged radially at arbitrary intervals on its outer periphery and provided so as to be able to protrude and retract in the radial direction.

[0041] In this embodiment, a disk-shaped base member 21 that is circular in plan view is exemplified because it is applied to a cylindrical caisson body 1, but the shape of the base member 21 can be any shape that corresponds to the interior space of the caisson body 1. In other words, the shape of the base member 21 is not limited to the circular shape disclosed in this embodiment, and for example, for a rectangular cylindrical caisson body 1, a base member 21 having a polygonal shape that corresponds to the interior space of the rectangular cylinder can be used. Furthermore, the base member 21 can be divided appropriately (divided into two in this embodiment) depending on the transportation means, such as the size of the loading platform of the transportation vehicle that transports the base member 21.

[0042] The inner scaffolding 2 is attached to the inside of the caisson body 1 by engaging the multiple protrusions 23 provided on the base member 21 with multiple engaging portions 13 provided in recessed or stepped shapes on the inside of the caisson body 1. In the case of a caisson body 1 made of RC segments, the inner circumferential surface is usually formed to be roughly flat, so in the caisson body 1 according to this embodiment, as shown in Figure 1, for example, the multiple engaging portions 13 capable of engaging the multiple protrusions 23 are formed in advance in recessed shapes on the inner circumferential edge on the upper end side at circumferential positions corresponding to the multiple protrusions 23.

[0043] 5, the engaged part 13 is a recessed cutout on the inner peripheral edge of the upper end of the caisson body 1, and opens vertically upward and radially inward. That is, the engaged part 13 is formed by locally recessing the inner surface of the caisson body 1, and forms a step 14 that widens in diameter in a stepped manner toward the vertically upward direction. As a result, as the inner scaffolding 2 descends, the protrusion 23 entering from the vertically upward direction comes into contact with the step 14 of the engaged part 13, and the protrusion 23 engages with the engaged part 13, and the inner scaffolding 2 is supported by the caisson body 1.

[0044] The locked portion 13 according to this embodiment has a pair of side walls 151, 152 facing each other on both sides in the circumferential direction, and the protruding portion 23 also restricts circumferential movement of the protruding portion 23 when the protruding portion 23 abuts against the side walls 151, 152. The pair of side walls 151, 152 formed on the locked portion 13 not only restricts circumferential movement of the protruding portion 23, but also functions as a guide that guides vertical movement of the protruding portion 23.

[0045] 2, 3, and 4, the protrusion 23 has a plurality of bearing portions 24 (four in this embodiment) arranged in series along the radial direction on the outer periphery of the upper surface of the base member 21, a shaft portion 25 supported by these bearing portions 24 so as to be slidable in the radial direction, and a stopper portion 26 formed integrally with the shaft portion 25 and which restricts the sliding of the shaft portion 25 by engaging with the bearing portions 24. In other words, the protrusion 23 supports the base member 21 inside the caisson body 1 by engaging the shaft portions 25, which protrude outward from the outer periphery of the base member 21, with the engaged portions 13 of the caisson body 1.

[0046] The bearing portion 24 has a first bearing portion 241 disposed at the innermost position in the radial direction, a second bearing portion 242 disposed at the outermost position in the radial direction, and a third bearing portion 243 and a fourth bearing portion 244 disposed between the first bearing portion 241 and the second bearing portion 242. The first bearing portion 241, the second bearing portion 242, the third bearing portion 243, and the fourth bearing portion 244 are fixed to the upper surface of the base member 21 by any fixing means such as welding.

[0047] The first bearing portion 241 and the second bearing portion 242 have circular first and second shaft holes 241a and 242a, respectively, through which the shaft portion 25 can pass, and support the shaft portion 25 inserted into the first and second shaft holes 241a and 242a in a state in which the shaft portion 25 is surrounded all around. The first and second shaft holes 241a and 242a have inner diameters that are slightly larger than the outer diameter of the shaft portion 25, and in a state in which the shaft portion 25 is supported by the first and second bearing portions 241 and 242, the shaft portion 25 is allowed to slide in the direction of the axis X and is also allowed to rotate about the axis X.

[0048] The third bearing portion 243 and the fourth bearing portion 244 have circular third shaft holes 243a and fourth shaft holes 244a, respectively, through which the shaft portion 25 can pass. The third shaft holes 243a and fourth shaft holes 244a each have an inner diameter slightly larger than that of the shaft portion 25, and similarly to the first shaft hole 241a and the second shaft hole 242a, allow the shaft portion 25 to slide in the direction of the axis X while also allowing the shaft portion 25 to rotate about the axis X in a state where it is journaled by the third bearing portion 243 and the fourth bearing portion 244. In addition, the third shaft hole 243a and the fourth shaft hole 244a are each provided with open grooves 243b and 244b formed by cutting out a portion in the circumferential direction.

[0049] The open grooves 243b, 244b communicate with the inside and outside of the third shaft hole 243a and the fourth shaft hole 244a at a specific phase in the circumferential direction of the third bearing portion 243 and the fourth bearing portion 244 (directly above the vertical position, which is the 12 o'clock position in this embodiment). That is, the open grooves 243b, 244b have a groove width slightly larger than the maximum width of the stopper portion 26, and allow the stopper portion 26 to pass through at the specific phase when the shaft portion 25 slides in the radial direction. Note that the phase of each open groove 243b, 244b only needs to be set to be the same (common) for the third bearing portion 243 and the fourth bearing portion 244, and the specific phase of both can be set at any circumferential position.

[0050] In this way, in the protrusion 23, the stopper portion 26 passes through the open grooves 243b and 244b, so that the stopper portion 26 can advance until it abuts against the first bearing portion 241 and can retreat until it abuts against the second bearing portion 242. In other words, in the protrusion 23, the stopper portion 26 moves between the first bearing portion 241 and the second bearing portion 242, and the shaft portion 25 can slide within the range in which the stopper portion 26 can move.

[0051] 3, when stopper portion 26 is positioned between second bearing portion 242 and fourth bearing portion 244, the tip of shaft portion 25 is positioned outside the outer periphery of base member 21, and shaft portion 25 protrudes from base member 21. On the other hand, when stopper portion 26 is positioned between first bearing portion 241 and third bearing portion 243, the tip of shaft portion 25 is positioned inside the outer periphery of base member 21, and shaft portion 25 is stored in base member 21.

[0052] The shaft portion 25 has a round bar shape with a circular cross section and a constant outer diameter in the direction of the axis X. A round bar-shaped stopper portion 26 extending radially of the shaft portion 25 is provided on the outer periphery of the shaft portion 25. The stopper portion 26 is fixed to the outer periphery of the shaft portion 25 by any fixing means, such as welding. Although the shape of the stopper portion 26 is exemplified as a round bar in this embodiment, it is sufficient that the stopper portion 26 is configured to be able to pass through each of the open grooves 243b, 244b. For example, any shape, such as a rectangular column shape, can be adopted depending on the configuration of the inner scaffolding 2 in relation to each of the open grooves 243b, 244b.

[0053] (Inner scaffolding installation method) The method for attaching the inner scaffolding 2 will be described below with reference to FIG.

[0054] When installing the inner scaffolding 2, first, as shown in Figure 6(a), with the tip of the shaft 25 of the protrusion 23 protruding outward beyond the outer periphery of the base member 21, the inner scaffolding 2, with the scaffolding member 22 fixed to the upper surface of the base member 21, is lifted by a crane (not shown) and hoisted inside the caisson body 1. At this time, to prevent the shaft 25 from unintentionally retracting, it is desirable to align the stopper 26 with a phase other than the specific phase and engage the stopper 26 with the outer end face of the fourth bearing 244 (see Figure 5(a)).

[0055] Then, the inner scaffolding 2 is lowered with the circumferential position of the protrusions 23 of the inner scaffolding 2 aligned with the circumferential position of the locked portion 13 of the caisson body 1, and as shown in Figure 6(b), the tip of the shaft 25 that protrudes outward from the outer periphery of the base member 21 is brought into contact with the step 14 of the locked portion 13, thereby locking the tip of the shaft 25 into the step 14. As a result, the base member 21 that constitutes the inner scaffolding 2 is supported on the inside of the caisson body 1 via the protrusions 23, and attachment of the inner scaffolding 2 to the caisson body 1 is completed.

[0056] (How to remove the internal scaffolding) A method for removing the inner scaffolding 2 will be described below with reference to FIG.

[0057] When removing the inner scaffolding 2, first, as shown in Figure 7(a), a wire rope W connected to a crane (not shown) is hung on the scaffolding member 22 of the inner scaffolding 2. Then, the inner scaffolding 2 is slightly lifted up by the crane (not shown) to move the shaft 25 of the protrusion 23, which is engaged with the engaged part 13 of the caisson body 1, away from the step 14 of the engaged part 13.

[0058] Next, with respect to the protrusion 23, the shaft 25 is rotated about the axis X to align the stopper 26 with the specific phase, thereby releasing the lock (engaged state) of the stopper 26 (see FIG. 3). Then, the stopper 26 is moved between the first bearing 241 and the third bearing 243 through the release grooves 243b and 244b, and the shaft 25 is retracted until the tip of the shaft 25 is positioned inside the outer circumferential edge of the base member 21, as shown in FIG. 7(b), thereby storing the shaft 25 in the base member 21.

[0059] Thereafter, although not specifically shown in the drawings, the stopper portion 26 is set to a phase other than the specific phase to prevent the shaft portion 25 from unintentionally protruding from the outer peripheral edge of the base member 21, and the stopper portion 26 is engaged with the inner end face of the third bearing portion 243, and then the inner scaffolding 2 is lifted and raised by a crane (not shown), as shown in Figure 7(c). This completes the removal of the inner scaffolding 2 from the caisson body 1.

[0060] (Operation and effect of the first embodiment) Below, we will specifically explain the characteristic functions and effects of the internal scaffolding mounting structure related to this embodiment.

[0061] In the conventional internal scaffolding installation structure, when installing the internal scaffolding 2 inside the caisson body 1, first, as shown in FIG. 21(a), a bracket installation scaffolding 20 for installing a bracket BKT (described later) is installed so as to be suspended inside the caisson body 1. Next, as shown in FIG. 21(b), a worker climbs onto the installed bracket installation scaffolding 20 and installs the bracket BKT inside the caisson body 1 using multiple anchor bolts AB (see FIG. 21(c)), and then removes the bracket installation scaffolding 20. This process is repeated until the brackets BKT are installed at predetermined locations inside the caisson body 1. Then, after all the brackets BKT have been installed, the internal scaffolding 2, with the scaffolding members 22 fixed to the upper surface of the base member 21, is lifted by a crane (not shown) and suspended inside the caisson body 1, as shown in FIG. 21(c). Then, as shown in FIG. 21(d), the inner scaffolding 2 is placed on the bracket BKT, completing the attachment of the inner scaffolding 2 to the caisson body 1.

[0062] As described above, the conventional mounting structure for the internal scaffolding is configured so that the internal scaffolding 2 is installed on the caisson body 1 via multiple brackets BKT. For this reason, in order to install the internal scaffolding 2, it is necessary to first mount the bracket mounting scaffolding 20 on the caisson body 1, then use this bracket mounting scaffolding 20 to mount the bracket BKT on the caisson body 1, and then remove the bracket mounting scaffolding 20, repeating this process. This makes the installation work for the internal scaffolding 2 cumbersome, and leaves room for improvement.

[0063] Furthermore, because the conventional mounting structure for the inner scaffolding installs the inner scaffolding 2 via the bracket BKT, after assembling the caisson body 1, the inner scaffolding 2 is lifted and removed by a crane as shown in Fig. 22(a), and then the bracket mounting scaffolding 20 is installed as shown in Fig. 22(b). Then, as shown in Fig. 22(c), the bracket is removed from the caisson body 1 using the bracket mounting scaffolding 20, and then the bracket mounting scaffolding 20 is removed as shown in Fig. 22(d). This requires repeating such operations. As a result, not only the installation work of the inner scaffolding 2 but also the removal work of the inner scaffolding 2 is complicated, and there has been a demand for a mounting structure for the inner scaffolding that allows the inner scaffolding 2 to be easily attached and detached.

[0064] In contrast, in this embodiment, the mounting structure for the inner scaffolding 2 is arranged so that it can be raised and lowered vertically by a lifting machine (a crane not shown) and is attached so that it can stand on its own inside the caisson body 1, and is equipped with an engaging portion 13 that is provided in a recessed or stepped shape on the inside of the caisson body 1, and a protrusion 23 (shaft 25) that is arranged on the inner scaffolding 2 so that it can freely move in and out in a radial direction perpendicular to the vertical direction and engages with the engaging portion 13.

[0065] In this way, in this embodiment, the inner scaffolding 2 can be attached to the caisson body 1 by extending the protrusions 23 (shafts 25) provided on the inner scaffolding 2 in the radial direction and engaging them with the engaging portions 13 provided on the inside of the caisson body 1. Therefore, compared to the conventional inner scaffolding attachment structure described above, which requires that brackets BKT for placing the inner scaffolding 2 be attached to the caisson body 1 in advance, the inner scaffolding 2 can be attached directly to the caisson body 1, making it easier to attach the inner scaffolding 2 to the caisson body 1.

[0066] Furthermore, in the case of this embodiment, when removing the inner scaffolding 2, the inner scaffolding 2 can be detached from the caisson body 1 simply by retracting the protrusion 23 (shaft 25) to release the engagement of the protrusion 23 with the engaged part 13. This makes it easy to remove the inner scaffolding 2 from the caisson body 1.

[0067] In addition, in this embodiment, the protrusion portion 23 has a plurality of bearing portions (first bearing portion 241, second bearing portion 242, third bearing portion 243 and fourth bearing portion 244) arranged on the upper surface of the inner scaffolding 2 along the radial direction, a shaft portion 25 that is supported by the bearing portions (first bearing portion 241, second bearing portion 242, third bearing portion 243 and fourth bearing portion 244) so ​​as to be able to slide in the radial direction and engages with the engaging portion 13 while protruding outward from the outer peripheral edge of the inner scaffolding 2, and a stopper portion 26 that is arranged integrally with or separately from the shaft portion 25 and engages with the bearing portions (in this embodiment, the third bearing portion 243 and the fourth bearing portion 244) to regulate the sliding of the shaft portion 25.

[0068] In this way, in this embodiment, it is possible to restrict the sliding of the shaft portion 25 by engaging the stopper portion 26 with the third bearing portion 243 and the fourth bearing portion 244. By mechanically restricting the sliding of the shaft portion 25 by the stopper portion 26 in this way, it is possible to reliably prevent the shaft portion 25 from unintentionally moving backward and falling off the engaged portion 13 when the inner scaffolding 2 is attached to the caisson body 1, thereby improving the safety of attaching the inner scaffolding 2.

[0069] In addition, in this embodiment, the shaft portion 25 is provided so as to be rotatable around the axis X of the shaft portion 25 in a bearing state by the bearing portions (first bearing portion 241, second bearing portion 242, third bearing portion 243, and fourth bearing portion 244), and at least one bearing portion (the third bearing portion 243 and the fourth bearing portion 244 in this embodiment) among the plurality of bearing portions (the first bearing portion 241, the second bearing portion 242, the third bearing portion 243, and the fourth bearing portion 244) rotates in a specific phase in the rotation direction of the shaft portion 25. The stopper portion 26 has open grooves 243b, 244b that communicate the inside and outside of the shaft portion 25 and allow the stopper portion 26 to pass through, and the stopper portion 26 is integrally formed with the shaft portion 25 and allows the shaft portion 25 to slide by passing through the open grooves 243b, 244b in the specific phase, and restricts the sliding of the shaft portion 25 by engaging with the bearing portions (in this embodiment, the third bearing portion 243 and the fourth bearing portion 244) in other phases except the specific phase.

[0070] In this way, in this embodiment, by rotating the shaft portion 25 and aligning the stopper portion 26 with the specific phase, it is possible to release the locked state of the stopper portion 26 with the third bearing portion 243 and the fourth bearing portion 244. This eliminates the risk of the locked state of the stopper portion 26 with the third bearing portion 243 and the fourth bearing portion 244 being unintentionally released, and the mounting safety of the inner scaffolding 2 can be more effectively improved.

[0071] Second Embodiment 8 to 10 show a second embodiment of the mounting structure for internal scaffolding according to the present invention, in which the storage means for the shaft 25 of the protrusion 23 in the first embodiment is changed. Note that the basic configuration other than this change is the same as that of the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted.

[0072] As shown in Figures 6 and 7, the mounting structure of the inner scaffolding in this embodiment includes, in addition to the configuration of the first embodiment, an anchor bolt AB, which is a fixed part, provided on the upper surface of the inner scaffolding 2 at a position more inward than the first bearing part 241 in the radial direction, and a rubber-string-like elastic member 3, which is provided between the anchor bolt AB and the stopper part 26 and exerts a contractile force when the shaft part 25 protrudes from the inner scaffolding 2.

[0073] That is, in this embodiment, the anchor bolt AB is provided on the top surface of the inner scaffolding 2, inside the first bearing portion 241 on the axis X, and one end 31 of the elastic member 3 is fixed to the anchor bolt AB, and the other end 32 of the elastic member 3 is hooked onto the stopper portion 26 when the inner scaffolding 2 is removed. As a result, when the inner scaffolding 2 is removed, the elastic member 3 is configured to use the contractile force to retract the shaft portion 25 until the tip of the shaft portion 25 is positioned inside the outer circumferential edge of the base member 21.

[0074] (How to remove the internal scaffolding) As described above, in this embodiment, the shaft 25 is stored using the contractile force of the elastic member 3, and the elastic member 3 is used when removing the inner scaffolding 2, so the method of attaching the inner scaffolding 2 is the same as in the first embodiment. Therefore, only the method of removing the inner scaffolding 2 will be explained below with reference to Figure 10.

[0075] When removing the inner scaffolding 2, first, as shown in FIG. 10(a), a wire rope W connected to a crane (not shown) is hung on the scaffolding member 22 of the inner scaffolding 2. Next, the shaft 25 of the protrusion 23 is rotated about the axis X to align the stopper 26 with the specific phase, thereby releasing the lock (engaged state) of the stopper 26. Then, the other end 32 of the elastic member 3, one end 31 of which is fixed to the anchor bolt AB, is hooked onto the unlocked stopper 26. At this point, the protrusion 23 is engaged with the locked portion 13, and static friction is acting between the step 14 of the locked portion 13 and the shaft 25. This static friction force resists the contraction force of the elastic member 3, maintaining the engaged state of the shaft 25 with the step 14 of the locked portion 13.

[0076] Next, the inner scaffolding 2 is slightly lifted by the crane (not shown), and the shaft 25 of the protrusion 23, which is engaged with the engaged portion 13 of the caisson body 1, is separated from the step 14 of the engaged portion 13. Then, the static friction force between the step 14 of the engaged portion 13 and the shaft 25 is released, and as shown in FIG. 10(b), the contraction force of the elastic member 3 pulls the stopper portion 26 toward the first bearing portion 241, and the stopper portion 26 automatically moves between the first bearing portion 241 and the third bearing portion 243 through the release grooves 243b and 244b. As a result, the shaft 25 retracts until the tip of the shaft 25 is positioned inside the outer periphery of the base member 21, and the shaft 25 is stored in the base member 21.

[0077] 10(c), the inner scaffolding 2 is raised by a crane (not shown). This completes the removal of the inner scaffolding 2 from the caisson body 1.

[0078] (Operation and effect of the second embodiment) As described above, in this embodiment, the inner scaffolding 2 is provided with a fixed portion (anchor bolt AB) provided on the upper surface thereof at a position more inward than the bearing portion (first bearing portion 241) in the radial direction, and an expandable elastic member 3 having one end 31 fixed to the fixed portion (anchor bolt AB) and the other end 32 hooked to the stopper portion 26, and exerting a contraction force when the shaft portion 25 protrudes from the inner scaffolding 2; when the inner scaffolding 2 is removed, the elastic member 3 exerts the contraction force when the other end 32 is hooked to the stopper portion 26, and the shaft portion 25 is retracted until the tip of the shaft portion 25 is positioned more inward than the outer edge of the inner scaffolding 2.

[0079] In this way, in this embodiment, when removing the inner scaffolding 2, the shaft 25 can be automatically retracted by the contraction force of the elastic member 3. This makes it possible to omit the work of releasing the locked state of the protrusion 23 with the locked portion 13, which is performed by retracting the shaft 25 when removing the inner scaffolding 2, making it even easier to remove the inner scaffolding 2.

[0080] In addition, in this embodiment, the contraction force of the elastic member 3 is set to be smaller than the friction force acting between the interlocking portion 13 (step portion 14) and the shaft portion 25, and when the inner scaffolding 2 is lifted by a lifting machine (crane not shown) and the shaft portion 25 is separated from the interlocking portion 13 (step portion 14) in the vertical direction, the contraction force of the elastic member 3 causes the shaft portion 25 to retract until the tip of the shaft portion 25 is positioned inside the outer edge of the inner scaffolding 2.

[0081] According to this aspect, the shaft 25 does not slide due to the contraction force of the elastic member 3 when friction between the shaft 25 and the locked portion 13 is acting, but retracts due to the contraction force of the elastic member 3 when the friction between the shaft 25 and the locked portion 13 is released. As a result, before the inner scaffolding 2 is lifted, the engagement state of the shaft 25 with the step 14 of the locked portion 13 is maintained due to friction between the shaft 25 and the step 14. This not only makes it possible to remove the inner scaffolding 2 more safely, but also makes it possible to retract the shaft 25 with a relatively small contraction force, allowing the use of an elastic member 3 with a relatively small elastic force, facilitating the installation work of the elastic member 3, which hooks the elastic member 3 onto the stopper portion 26 against the elastic force of the elastic member 3. As a result, the removal work of the inner scaffolding 2 can be performed even more easily.

[0082] Third Embodiment 11 and 12 show a third embodiment of the mounting structure for internal scaffolding according to the present invention, in which the specific configuration of the stopper portion 26 in the first embodiment is changed. Note that the basic configuration other than this change is the same as that of the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted.

[0083] 11 and 12, the mounting structure for the internal scaffolding according to this embodiment has an insertion hole 250 that opens radially through the shaft 25, and a locking pin 27 is inserted into this insertion hole 250, thereby replacing the slide lock mechanism of the shaft 25 by the stopper part 26 according to the first embodiment. The locking pin 27 is formed by, for example, a well-known bolt 271, and is fixed to the insertion hole 250 by screwing a lock nut 272 into the tip of the bolt 271.

[0084] As described above, in this embodiment, stopper portion 26 is configured by locking pin 27 formed separately from shaft portion 25, and the bolt 271 and lock nut 272 constituting locking pin 27 are locked with third bearing portion 243 or fourth bearing portion 244, thereby restricting sliding (retraction) of shaft portion 25 in the storage direction. In other words, unlike the first embodiment in which the locked state of stopper portion 26 is released through release grooves 243b, 244b, this embodiment is configured such that, when locking pin 27 is inserted into insertion hole 250, sliding (retraction) of shaft portion 25 in the storage direction is restricted regardless of the phase of shaft portion 25.

[0085] In this embodiment, as in the first embodiment, a stopper portion 26 is integrally formed on the shaft portion 25, but the stopper portion 26 in this embodiment is not intended to restrict the sliding of the shaft portion 25, but rather functions as a grip portion (handle) when sliding the shaft portion 25.

[0086] (Operation and effect of the third embodiment) As described above, in this embodiment, the shaft portion 25 has an insertion hole 250 that opens radially, and the stopper portion 26 is composed of a locking member (locking pin 27) that is separate from the shaft portion 25 and is detachably attached to the insertion hole 250, and allows the shaft portion 25 to slide when the locking member (locking pin 27) is removed from the insertion hole 250, and when the locking member (locking pin 27) is inserted into the insertion hole 250, it locks with the bearing portion (third bearing portion 243 or fourth bearing portion 244) to restrict the sliding of the shaft portion 25.

[0087] According to this aspect, when the locking pin 27, which is provided separately from the shaft 25, is disengaged from the insertion hole 250, the shaft 25 is allowed to slide, and when the locking pin 27 is inserted into the insertion hole 250, the locking pin 27 is locked with the third bearing portion 243 or the fourth bearing portion, restricting the sliding of the shaft 25. In other words, when the locking pin 27 is inserted into the insertion hole 250, the sliding of the shaft 25 can be restricted regardless of the phase of the shaft 25. This eliminates the risk of the locking pin 27 being unintentionally released from the locked state with the third bearing portion 243 or the fourth bearing portion, and the safety of the installation of the inner scaffolding 2 can be more effectively improved.

[0088] Furthermore, according to this aspect, the sliding of the shaft portion 25 can be restricted simply by inserting the locking pin 27 into the insertion hole 250. This has the advantage that the sliding of the shaft portion 25 can be restricted without performing any special operation, such as rotating the shaft portion 25 to align it with a specific phase as in the first embodiment, for example.

[0089] [Fourth embodiment] 13 and 14 show a fourth embodiment of the mounting structure for internal scaffolding according to the present invention, and this embodiment is mainly a combination of the third embodiment and the automatic storage structure of the shaft portion 25 using the elastic member 3 disclosed in the second embodiment. Note that the basic configuration other than these changes is basically the same as that of the third embodiment. Therefore, the same components as those of the third embodiment are denoted by the same reference numerals, and a description thereof will be omitted.

[0090] 13 and 14, the mounting structure for the internal scaffolding according to this embodiment has a lever portion 28 extending radially from the outer periphery of the shaft portion 25, the lever portion 28 moving between the outer surface of the first bearing portion 241 and the inner surface of the second bearing portion 242. The lever portion 28 has a cylindrical shape extending in a direction generally perpendicular to the shaft portion 25, and is formed integrally with the shaft portion 25.

[0091] Furthermore, in this embodiment, the third bearing portion 243 or the fourth bearing portion 244 in the third embodiment is eliminated, and instead a guide rail GL is provided between the first bearing portion 241 and the second bearing portion 242 to guide the movement of the lever portion 28 moving back and forth between the first bearing portion 241 and the second bearing portion 242.

[0092] The guide rail GL is composed of a pair of rail constituent members GL1, GL2 that are suspended in parallel between the outer surface of the first bearing portion 241 and the inner surface of the second bearing portion 242. Each of the pair of rail constituent members GL1, GL2 is cylindrical with a circular cross section, and is in line contact with the lever portion 28, thereby reducing the sliding resistance of the lever portion 28.

[0093] In this embodiment, the second shaft hole 242a of the second bearing portion 242 is formed as an elongated hole extending in the vertical direction, and widened portions 242b are formed on both sides of the lower end of the second shaft hole 242a by cutting out the second shaft hole 242a in a concave shape along a direction perpendicular to the vertical direction. The widened portions 242b are formed as elongated holes through which the locking pin 27 attached so as to pass through the shaft portion 25 can pass.

[0094] With this configuration, when shaft portion 25 of protrusion 23 is locked to step portion 14 of locked portion 13, shaft portion 25 is lifted vertically upward and is positioned above second shaft hole 242a, and locking pin 27 is locked to the outer surface of second bearing portion 242, restricting sliding of shaft portion 25. On the other hand, when base member 21 is lifted and shaft portion 25 of protrusion 23 is separated from step portion 14 of locked portion 13, shaft portion 25 moves vertically downward due to its own weight and is positioned below second shaft hole 242a, and widened portion 242b allows locking pin 27 to pass through, allowing shaft portion 25 to slide.

[0095] Furthermore, in this embodiment, as in the second embodiment, an anchor bolt AB, which serves as a fixed part, is provided on the upper surface of the inner scaffolding 2 at a position on the axis X and inside the first bearing part 241 in the radial direction, and a rubber-string-like elastic member 3, which exerts a contractile force when the shank 25 protrudes from the inner scaffolding 2, is interposed between this anchor bolt AB and the lever part 28. As in the second embodiment, when the inner scaffolding 2 is removed, one end 31 of the elastic member 3 is fixed to the anchor bolt AB and the other end 32 is hooked onto the lever part 28, so that when the inner scaffolding 2 is removed, the contractile force causes the shank 25 to retract via the lever part 28 until the tip of the shank 25 is positioned inside the outer circumferential edge of the base member 21.

[0096] (Operation and effect of the fourth embodiment) As described above, in this embodiment, the scaffolding includes the lever portion 28 provided integrally with the shaft portion 25, the fixed portion (anchor bolt AB) provided on the upper surface of the inner scaffolding 2 at a position more inward than the bearing portion (second bearing portion 242) in the radial direction, and the stretchable elastic member 3, one end 31 of which is fixed to the fixed portion (anchor bolt AB) and the other end 32 of which is hooked onto the lever portion 28, and which exerts a contractile force when the shaft portion 25 protrudes from the inner scaffolding 2. The receiving portion 242 supports the shaft portion 25 by means of a long hole-shaped shaft hole (second shaft hole 242a) extending in the vertical direction, and the shaft hole (second shaft hole 242a) has widened portions 242b on both sides of the lower end portion in the vertical direction that expand the shaft hole (second shaft hole 242a) in a direction perpendicular to the vertical direction to allow the stopper portion (locking pin 27) to pass through, and when the shaft portion 25 is locked to the locked portion 13, the shaft portion 25 is located above the shaft hole (second shaft hole 242a) in the vertical direction. The stopper portion (locking pin 27) is locked to the end face of the bearing portion (second bearing portion 242), while the shaft portion 25 is separated from the locked portion 13, the shaft portion 25 is positioned below the shaft hole (second shaft hole 242a) in the vertical direction, thereby allowing the stopper portion (locking pin 27) to pass through the widened portion 242b. When the inner scaffolding 2 is removed, the elastic member 3 is in a state where the stopper portion (locking pin 27) is locked to the outer surface of the bearing portion (second bearing portion 242), and the other end 32 of the lever The inner scaffolding 2 is lifted by a lifting machine (crane not shown), the stopper portion (locking pin 27) moves downward into the shaft hole (second shaft hole 242a) due to its own weight, and the widening portion 242b releases the locking state between the stopper portion (locking pin 27) and the end face of the bearing portion (second bearing portion 242), and the contraction force of the elastic member 3 causes the shaft portion 25 to retract until the tip of the shaft portion 25 is positioned inside the outer edge of the inner scaffolding 2.

[0097] According to this aspect, when removing the inner scaffolding 2, the shaft 25 can be automatically retracted by the contraction force of the elastic member 3. This makes it possible to omit the work of releasing the locked state of the protrusion 23 with the locked portion 13, which is performed by retracting the shaft 25 when removing the inner scaffolding 2, making it even easier to remove the inner scaffolding 2.

[0098] Moreover, in this embodiment, when the shaft portion 25 of the protrusion portion 23 is engaged with the engaging portion 13, the shaft portion 25 is positioned above the second shaft hole 242a and the engaging pin 27 is engaged with the end face of the second bearing portion 242, and when the shaft portion 25 of the protrusion portion 23 is spaced away from the step portion 14 of the engaging portion 13, the shaft portion 25 is positioned below the second shaft hole 242a and allows the engaging pin 27 to pass through the widened portion 242b. Therefore, when the shaft 25 of the protruding portion 23 is engaged with the step 14 of the engaged portion 13 and it is necessary to restrict the sliding of the shaft 25, the locking pin 27 restricts the sliding of the shaft 25, and when the shaft 25 of the protruding portion 23 is separated from the step 14 of the engaged portion 13 and it is not necessary to restrict the sliding of the shaft 25, the widened portion 242b allows the shaft 25 to slide. In this way, by automatically restricting or releasing the sliding of the shaft 25 as needed, it is possible to improve not only the ease of removing the inner scaffolding 2 but also the ease of installing the inner scaffolding 2, and it is possible to further facilitate the work of installing and removing the inner scaffolding 2.

[0099] In particular, by combining the configuration that automates the sliding restriction of the shaft 25 with the configuration that automates the storage of the shaft 25 by the elastic member 3, these two configurations are organically related, and when removing the inner scaffolding 2, simply by hooking the elastic member 3 onto the lever 28, the locked state by the locking pin 27 can be released and the shaft 25 can be stored by the elastic member 3 automatically. This significantly reduces the number of steps required for the removal of the inner scaffolding 2, making the removal of the inner scaffolding 2 even easier.

[0100] Fifth Embodiment 15 to 19 show a fifth embodiment of the mounting structure for internal scaffolding according to the present invention, in which the specific configuration of the protrusion 23 in the first embodiment is changed. Note that the basic configuration other than these changes is the same as that of the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted.

[0101] 15, 16 and 17, the mounting structure for the inner scaffolding according to this embodiment has a receiving groove 210 cut out in the outer peripheral edge of the base member 21 of the inner scaffolding 2, the receiving groove 210 opening outward in the radial direction (diameter direction), and a rotating pin 29 constituting the protrusion 23 is rotatably supported in this receiving groove 210. That is, in this embodiment, the rotating pin 29 is configured to rotate so that it is displaced between a horizontal phase in which it is roughly parallel to the horizontal direction and a vertical phase in which it is roughly parallel to the vertical direction, and in the horizontal phase, one end of the rotating pin 29 protrudes outward from the outer peripheral edge of the base member 21, while in the vertical phase, both ends of the rotating pin 29 are located inside the outer peripheral edge of the base member 21.

[0102] Receiving groove 210 has bottomed portion 210a provided on the inside in the radial direction and having a vertical lower end closed by bottom wall 210c, and open portion 210b provided on the outside in the radial direction and penetrating in the vertical direction. That is, this receiving groove 210 has bottomed portion 210a on the inside, which is open only on the vertically upper side, and is closed on the vertically lower side by bottom wall 210c, while the outside is open portion 210b, which is open on both vertical sides.

[0103] The bottomed portion 210a has a bottom wall 210c that closes the vertically lower side, and a pair of side walls 210d, 210e that rise vertically from both sides of the bottom wall 210c to the vertically upper side and face both circumferential sides of the base member 21. The bottomed portion 210a has a depth (the vertical distance from the upper surface of the base member 21 to the bottom wall 210c) that is equal to or greater than the thickness T of the rotation pin 29. As a result, the other end of the rotation pin 29 is accommodated in an accommodation space formed by the bottom wall 210c and the pair of side walls 210d, 210e, thereby enabling the horizontal phase of the rotation pin 29.

[0104] The open portion 210b has a pair of side walls 210d, 210e that are continuous from the bottom portion 210a and are arranged facing each other on both sides in the circumferential direction, and is open on both vertical sides and radially outward. Furthermore, the open portion 210b has a radial width that is equal to or slightly larger than the thickness T of the rotation pin 29, which will be described later, and the pair of side walls 210d, 210e are recessed to form concave supported portions 130a, 130b that can bear a pair of support portions 293a, 293b that protrude from both sides of the rotation pin 29. As a result, in the open portion 210b, both ends of the rotation pin 29 protrude in the vertical direction, allowing the rotation pin 29 to be vertically rotated.

[0105] The rotation pin 29 has a general portion 290 formed in a rectangular column shape with a constant thickness T and width W, a first end portion 291 provided at one end of the general portion 290 and accommodated in the bottomed portion 210a of the receiving groove 210 in the horizontal phase, and a second end portion 292 provided at the other end of the general portion 290 and engaged with the step portion 14 of the engaged portion 13 of the caisson body 1 in the horizontal phase. The first end portion 291 and the second end portion 292 are each formed in a roughly arc shape with a thickness T gradually decreasing toward the tip. As a result, even when the rotation pin 29 is in an inclined state, when the second end portion 292 abuts against the step portion 14 during installation of the inner scaffolding 2, a moment is generated that lifts the second end portion 292 against the rotation pin 29, allowing it to automatically displace to the horizontal phase.

[0106] The general portion 290 has a pair of support portions 293a, 293b protruding on both sides in the width direction, and the pair of support portions 293a, 293b respectively rotatably engage with the supported portions 130a, 130b in the open portion 210b of the receiving groove 210. As a result, the pair of support portions 293a, 293b engage with the supported portions 130a, 130b of the receiving groove 210, and the rotation pin 29 is rotatably supported by the supported portions 130a, 130b of the receiving groove 210 via the pair of support portions 293a, 293b.

[0107] With the above-described configuration, the first end 291 of the rotating pin 29 abuts against the bottom wall 210c of the receiving groove 210, and the second end 292 abuts against the step 14 of the locked portion 13 of the caisson body 1, and the moment in the direction of arrow D1 generated by the second end 292 abutting against the step 14 is supported by the bottom wall 210c, thereby maintaining the horizontal phase and maintaining the attached state of the inner scaffolding 2 to the caisson body 1. Meanwhile, by rotating the rotating pin 29 from this horizontal phase in the direction of arrow D2, at the open portion 210b, the first end 291 protrudes vertically upward and the second end 292 of the rotating pin 29 protrudes vertically downward, thereby maintaining the vertical phase of the rotating pin 29.

[0108] (Inner scaffolding installation method) The method for attaching the inner scaffolding 2 will be described below with reference to FIG.

[0109] 18(a), the inner scaffolding 2, with the second end 292 of the rotating pin 29 of the protrusion 23 protruding outward from the outer periphery of the base member 21 (for example, in a horizontal phase), is then lifted by a crane (not shown) and hoisted inside the caisson body 1. Note that when the inner scaffolding 2 is hoisted inside the caisson body 1, the rotating pin 29 does not necessarily have to be in a horizontal phase, as long as the first end 291 is tilted inward (towards the bottomed portion 210a).

[0110] 18(b), the inner scaffolding 2 is lowered with the circumferential position of the protrusion 23 of the inner scaffolding 2 aligned with the circumferential position of the locked portion 13 of the caisson body 1, and the second end 292 of the rotating pin 29, which protrudes outward from the outer periphery of the base member 21, abuts against the step 14 of the locked portion 13. Then, due to the moment generated by the abutment of the second end 292 of the rotating pin 29 with the step 14, the first end 291 abuts against the bottom wall 210c of the bottomed portion 210a, and the rotating pin 29 is locked to the step 14. As a result, the base member 21 constituting the inner scaffolding 2 is supported inside the caisson body 1 via the protrusion 23, and attachment of the inner scaffolding 2 to the caisson body 1 is completed.

[0111] (How to remove the internal scaffolding) A method for removing the inner scaffolding 2 will be described below with reference to FIG.

[0112] When removing the inner scaffolding 2, first, as shown in Figure 19(a), a wire rope W connected to a crane (not shown) is hung on the scaffolding member 22 of the inner scaffolding 2. Thereafter, the inner scaffolding 2 is lifted up by the crane (not shown).

[0113] 19(b), as the inner scaffolding 2 rises, the second end 292 of the rotating pin 29 comes into contact with the lower end of the caisson body 1x that is stacked vertically above the inner scaffolding 2, and a moment acts to push the second end 292 vertically downward, causing the rotating pin 29 to assume a vertical phase. As a result, both the first end 291 and the second end 292 of the rotating pin 29 are positioned inside the outer periphery of the base member 21, and the rotating pin 29 is stored in the base member 21.

[0114] Then, with the rotation pin 29 maintained in the vertical position, the inner scaffolding 2 is raised by a crane (not shown), as shown in Figure 19(c), thereby completing the removal of the inner scaffolding 2 from the caisson body 1.

[0115] (Operation and effect of the fifth embodiment) As described above, in this embodiment, the inner scaffolding 2 has a receiving groove 210 cut out in the outer peripheral edge portion, and the receiving groove 210 is provided on the inside in the radial direction and has a bottomed portion 210a whose vertical lower end is closed by a bottom wall 210c, and is provided on the outside in the radial direction and has an open portion 210b that penetrates in the vertical direction, and the protrusion portion 23 is generally linear, and is provided so as to be rotatable about the middle portion (general portion 290) as a fulcrum by having the middle portion (general portion 290) supported by the open portion 210b of the receiving groove 210, and is displaced between a horizontal phase that is generally parallel to the horizontal direction and a vertical phase that is generally parallel to the vertical direction, and is In the horizontal phase, one end (first end 291) facing inward in the radial direction abuts the upper surface of the bottom wall 210c, restricting the rotation of the protrusion 23, and the other end (second end 292) facing outward in the radial direction protrudes outward from the outer peripheral edge of the inner scaffolding 2 and engages with the engaging portion 13, thereby holding the inner scaffolding 2 in a self-supporting state, while in the vertical phase, both ends of the protrusion 23 at the open portion 210b are facing in the vertical direction of the inner scaffolding 2, and both ends of the protrusion 23 are positioned inside the outer peripheral edge of the inner scaffolding 2 in the radial direction, allowing the inner scaffolding 2 to rise and fall.

[0116] According to this aspect, it is possible to switch between an engaged state of the protrusion 23 with respect to the locked portion 13 and a released state of the protrusion 23 simply by changing the phase in the rotational direction of the rotation pin 29 that constitutes the protrusion 23. This makes it relatively easy to switch the engaged state of the protrusion 23 with respect to the locked portion 13, compared to the aspect in which the shaft 25 is slid to switch the engaged state of the protrusion 23 with respect to the locked portion 13, and makes it even easier and more efficient to attach and detach the inner scaffolding 2 to and from the caisson body 1.

[0117] Furthermore, in this embodiment, when the inner scaffolding 2 is installed, the protrusion 23 (rotation pin 29) protrudes outward from the outer peripheral edge of the inner scaffolding 2, and when it is in an inclined phase between the horizontal phase and the vertical phase, as the inner scaffolding 2 moves downward, the other end (second end 292) abuts against the engaging portion 13, causing one end (first end 291) to rotate in a direction approaching the bottom wall 210c and automatically displace to the horizontal phase.

[0118] According to this aspect, when installing the inner scaffolding 2, simply by lowering the inner scaffolding 2, the rotating pin 29, which is in the inclined phase, will abut against the locked portion 13, causing it to automatically rotate and displacing the rotating pin 29 to the horizontal phase. As a result, even if the rotating pin 29 is not in a completely horizontal phase beforehand when installing the inner scaffolding 2, it is possible to automatically displace the rotating pin 29 to the horizontal phase and ensure that the rotating pin 29 and the locked portion 13 are locked together, making the installation work of the inner scaffolding 2 even easier.

[0119] In addition, in this embodiment, when the inner scaffolding 2 is removed, the other end (second end 292) of the protrusion 23 (rotation pin 29) protrudes outward from the outer peripheral edge of the inner scaffolding 2 as the inner scaffolding 2 moves upward, and comes into contact with the caisson body 1x stacked vertically above the inner scaffolding 2, causing one end (first end 291) to rotate in a direction away from the bottom wall 210c and automatically displace to the vertical phase.

[0120] According to this aspect, when removing the inner scaffolding 2, simply by raising the inner scaffolding 2, the rotation pin 29, which is in the horizontal phase, abuts against the upper caisson body 1x, and automatically rotates, making it possible to displace the rotation pin 29 to the vertical phase. As a result, when removing the inner scaffolding 2, the rotation pin 29 can be automatically stored in the inner scaffolding 2 without the worker having to do anything to it, making the removal work of the inner scaffolding 2 even easier.

[0121] The present invention is not limited to the configurations exemplified in the above-described embodiments, and can be freely modified according to the specifications of the target object within the scope of the present invention.

[0122] In particular, in each of the above-described embodiments, an example is given in which the mounting structure for internal scaffolding according to the present invention is applied to a caisson skeleton 1 formed by assembling ring pieces 11 made of reinforced concrete segments. However, the mounting structure for internal scaffolding according to the present invention is not limited to the ring pieces 11 made of reinforced concrete segments, and it goes without saying that it can also be applied to a caisson skeleton 1' formed by assembling ring pieces 11' made of steel segments, which are often used in the well-known Urban Ring Construction Method, as shown in Figure 20. Note that for this caisson skeleton 1' made of steel segments, the internal scaffolding 2 can be attached to the inside of the caisson skeleton 1' by engaging the protrusions 23 with the step portions 150 formed by ribs 15 protruding from the inside of the caisson skeleton 1'. [Explanation of symbols]

[0123] 1...Caisson body 1x...caisson body 1´…Caisson body 10...Unit earth retaining wall 11...Ring piece 11´…Ring piece 12...Cutting edge ring 13…Locked part 14...Double part 15...Rib (retained portion) 150...Step 2...Inner scaffolding 21...Base member 210...receptive groove 210a…bottomed part 210b...Open part 210c…Bottom wall 210d,210e…side wall 22...Scaffolding material 23...Protrusion 24...Bearing part 241...First bearing part (bearing part) 241a...1st shaft hole (shaft hole) 242…Second bearing part (bearing part) 242a...Second shaft hole (shaft hole) 242b... Widened section 243...Third bearing part (bearing part) 243a...Third shaft hole (shaft hole) 243b…Open groove 244...Fourth bearing part (bearing part) 244a...Fourth shaft hole (shaft hole) 244b…Open groove 25...shaft (protrusion) 250...insertion hole 26...Stopper part 27...Latching pin (locking member) 271...Bolt 272...Lock nut 28...Lever section 29...Rotation pin (protrusion) 291...First end (one end) 292...Second end (other end) 3...Elastic member AB...Anchor bolt (fixed part) X…Axis line

Claims

1. An internal scaffolding mounting structure that can be raised and lowered vertically by a lifting machine and attached independently to the inside of a caisson body, A recessed or stepped engaging portion provided on the inside of the caisson body; a protrusion provided on the inner scaffolding so as to be able to protrude and retract in a radial direction perpendicular to the vertical direction and which engages with the engaged portion, the protrusion having: a plurality of bearing portions provided on the upper surface of the inner scaffolding along the radial direction; a shaft portion which is supported by the bearing portions so as to be able to slide in the radial direction and which engages with the engaged portion in a state where it protrudes outward from the outer periphery of the inner scaffolding; and a stopper portion which is provided integrally with or separately from the shaft portion and which engages with the bearing portion to restrict sliding of the shaft portion; A fixing portion provided on the upper surface of the inner scaffolding at a position more inward than the bearing portion in the radial direction; An expandable elastic member having one end fixed to the fixing portion and the other end hooked to the stopper portion, and exerting a contraction force in a state where the shaft portion protrudes from the inner scaffold; Equipped with the shaft portion is provided so as to be rotatable about an axis of the shaft portion in a state where the shaft portion is supported by the bearing portion, At least one of the bearing portions has an open groove formed to communicate the inside and outside of the bearing portion at a specific phase in the rotation direction of the shaft portion and to allow the stopper portion to pass through, the stopper portion is provided integrally with the shaft portion, and passes through the open groove in the specific phase to allow the shaft portion to slide, and is engaged with the bearing portion in other phases except for the specific phase to restrict the sliding of the shaft portion, The elastic member exerts the contraction force by hooking the other end onto the stopper portion when the inner scaffolding is removed, The contraction force of the elastic member is set to be smaller than the friction force acting between the locked portion and the shank when the shank is pressed against the locked portion by the weight of the inner scaffolding when the shank is locked to the locked portion, When the shaft portion is locked to the locked portion, the frictional force acting between the locked portion and the shaft portion restricts sliding of the shaft portion. When the shaft portion is separated from the locked portion, the frictional force is released, allowing the shaft portion to slide. When the inner scaffolding is removed, the elastic member releases the engagement of the stopper portion with the bearing portion and lifts the inner scaffolding by the crane, thereby releasing the friction between the engaged portion and the shaft portion, and causes the tip of the shaft portion to retract to a position more inward than the outer edge of the inner scaffolding based on the contraction force. An internal scaffolding mounting structure.

2. An internal scaffolding mounting structure that can be raised and lowered vertically by a lifting machine and attached independently to the inside of a caisson body, A recessed or stepped engaging portion provided on the inside of the caisson body; a protrusion provided on the inner scaffolding so as to be able to protrude and retract in a radial direction perpendicular to the vertical direction and which engages with the engaged portion, the protrusion having: a plurality of bearing portions provided on the upper surface of the inner scaffolding along the radial direction; a shaft portion which is supported by the bearing portions so as to be able to slide in the radial direction and which engages with the engaged portion in a state where it protrudes outward from the outer periphery of the inner scaffolding; and a stopper portion which is provided integrally with or separately from the shaft portion and which engages with the bearing portion to restrict sliding of the shaft portion; a lever portion integrally provided with the shaft portion; A fixing portion provided on the upper surface of the inner scaffolding at a position more inward than the bearing portion in the radial direction; An expandable elastic member having one end fixed to the fixing portion and the other end hooked to the lever portion, the elastic member exerting a contraction force in a state where the shaft portion protrudes from the inner footing; Equipped with the bearing portion supports the shaft portion by means of a long hole-shaped shaft hole extending in the vertical direction, The shaft hole has widened portions on both sides of a lower end portion in the vertical direction that widen the shaft hole in a direction perpendicular to the vertical direction to allow the stopper portion to pass through, When the shaft portion is locked to the locked portion, the shaft portion is lifted vertically upward, and the stopper portion locks onto the end surface of the bearing portion, restricting the sliding of the shaft portion. When the shaft portion is separated from the locked portion, the shaft portion moves vertically downward due to its own weight, thereby allowing the stopper portion to pass through the widened portion and allowing the shaft portion to slide, When the inner scaffolding is removed, the other end of the elastic member is hooked onto the lever portion with the stopper portion engaged with the end face of the bearing portion, and when the inner scaffolding is lifted by the crane and the engaged state between the stopper portion and the bearing portion is released, the tip of the shaft portion is retracted based on the contraction force to a position inside the outer edge of the inner scaffolding. An internal scaffolding mounting structure.

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