JP6032530B2 - Seismic joint structure of cable protection tube - Google Patents

Description

  The present invention relates to a seismic joint structure for a cable protection tube.

  The cable protection tube is installed for the purpose of accommodating and protecting a power cable, a communication cable, and the like. As the material, FRP, FRPM, vinyl chloride or the like is adopted. For example, FRP cable protection pipes are used for the road bridge framing parts, and FRPM pipes are used for the buried parts, depending on the application.

  The diameter of the cable protection pipe adopted for the road bridge pier is defined from φ100 to φ300, but φ125 to φ150 is often adopted as a general-purpose size. One or more cable protection tubes are installed together according to the condition of the cables to be accommodated, and they are supported at regular intervals by brackets installed on the main girder of the bridge girder of the road bridge.

  In addition, the abutments and piers arranged at both ends of the span are the fulcrum portions of the bridge, and in the vicinity of the fulcrum portions, expansion joints that allow expansion and contraction in the tube axis direction of the cable protection tube are often installed. . The purpose of such an expansion joint is to mitigate an increase in stress by causing the cable protection tube to follow the expansion and contraction in response to a minute expansion and contraction in the tube axis direction accompanying the temperature change of the main girder. For this reason, it cannot be said that itself has sufficient seismic performance.

  However, for example, in the policy generally applied as seismic reinforcement for road bridges, road bridges do not necessarily have to maintain normal soundness for large-scale earthquakes. Minimal damage is allowed. For this reason, the technique of not only improving the intensity | strength of a structural member but accepting a big displacement and reducing the external force by an earthquake is taken.

  As a result of these, the assumed displacement of the superstructure and substructure (abutments, piers) at the time of the earthquake reaches several tens of centimeters in both the direction of the bridge axis and the direction perpendicular to the bridge axis. . This is different from the conventionally accepted displacement amount in which the temperature expansion and contraction of the main girder is considered only in the bridge axis direction.

  As described above, a large relative displacement occurs between the bridge superstructure and the substructure in the bridge axis direction and the direction perpendicular to the bridge axis during the earthquake. Since the general attachment part (support point other than the fulcrum part) is supported by the bracket installed on the main girder, it is not necessary to consider these displacements. However, at the fulcrum where the displacement is concentrated, in order to maintain the soundness of the pipe line, the bridge axis direction and the bridge axis between the pipe body fixed to the abutment and the supporting pipe supported by the main girder. It is necessary to provide a function capable of following a displacement assumed in a perpendicular direction.

  In addition, it follows the displacement assumed in the pipe axis direction (bridge axis direction) and the pipe axis perpendicular direction (bridge axis perpendicular direction) between the pipe body fixed to the abutment and the ground and the pipe connected to it. As a cable protection tube that can be used, for example, there is one described in Patent Document 1.

Japanese Utility Model Publication No. 7-29391

However, in the technique described in the above-mentioned Patent Document 1, a member for exhibiting a water stop function and a member for exhibiting a retaining function are separately provided in the sliding portion of the stretchable portion. . For this reason, the structure tends to be complicated. The complexity of the structure leads to an increase in cost, so a more simplified and inexpensive structure is required.
In the technique described in Patent Document 1, many types of dedicated members are prepared for each of an expandable portion that allows expansion and contraction in the tube axis direction and a bending portion that allows bending in the tube axis direction. There is a problem that must be done. Furthermore, the technique described in Patent Document 1 has a problem that the construction is complicated.

  Therefore, the first object of the present invention is to make the structure simple and inexpensive in the earthquake-proof joint structure of the cable protection tube having the bent portion and the stretchable portion. Reducing it is a second problem, and facilitating construction is a third problem.

  In order to solve the above problems, the present invention includes at least two bent portions that allow bending in the tube axis direction, and includes an expandable portion that allows expansion and contraction in the tube axis direction between the two bent portions. The telescopic portion includes a sliding portion in which an inner tube portion and an outer tube portion slide in the tube axis direction, and a rubber ring is provided at an end portion of the inner tube portion or the outer tube portion of the sliding portion. In addition, a seismic joint structure for a cable protection tube is adopted in which the rubber ring has a water stopping function and a retaining function for the sliding portion.

  According to this configuration, since the rubber ring exhibits both the water stopping function and the retaining function for the sliding portion, the cost can be reduced by simplifying the structure.

  Further, in this configuration, the sliding portion is provided at an end portion on one bent portion side of the telescopic portion and an end portion on the other bent portion side, and the both sliding portions are continuous one. The structure provided in the both ends of a straight pipe of a book is employable.

According to this structure, since a general straight pipe can be used as a member which comprises an expansion-contraction part, the kind of component to be used can be reduced.
That is, a tubular body used for a seismic joint structure of a cable protection tube having this configuration, which is used for the sliding portion of the expansion / contraction portion, and is connected to both ends of one continuous straight tube, respectively. It is possible to employ a tube body that can be provided with a sliding portion that allows relative movement in the tube axis direction.

  Further, as another configuration, at least two bent portions that allow bending in the tube axis direction are provided, and an extended portion that allows expansion and contraction in the tube axis direction is provided between the two bent portions, A cover that includes a sliding portion in which the tube portion and the outer tube portion slide in the tube axis direction, and prevents a gap between the inner tube portion and the outer tube portion of both the sliding portions from being exposed to the outside. It is possible to adopt a seismic joint structure for a cable protection tube, which is characterized by being provided.

  In the seismic joint structure of a cable protection tube, if foreign matter adheres to the pipe body, it causes problems in appearance and also shortens the life of the pipe body. In particular, the adhesion of foreign matter to the stretchable part may cause a situation in which the stretchable part does not function properly during an earthquake in addition to the appearance and life problems. Therefore, by providing a cover that covers the sliding portion, such a situation can be prevented and the stability of the piping structure can be improved.

  Further, as another configuration, at least two bent portions that allow bending in the tube axis direction are provided, and an extension portion that allows expansion and contraction in the tube axis direction is provided between the two bent portions, and the two bent portions are provided. The joint is provided with a detachment prevention joint on the outer side in the tube axis direction, and the detachment prevention joint can be fixed by relatively rotating the bent part side pipe body and the opposite side pipe body around the pipe axis. It is possible to adopt a seismic joint structure for cable protection tubes characterized by

  According to this configuration, it is possible to connect a pair of tubular bodies constituting the detachment preventing joint to other tubular bodies adjacent to each other in the tube axis direction simply by rotating around the tube axis. The other tubular body adjacent in the tube axis direction can be, for example, a tubular body fixed to an abutment constituting a fulcrum portion of the cable protection tube. For this reason, construction is easy.

  This invention can improve the stability of the piping structure in the seismic joint structure of the cable protection pipe provided with the bent portion and the expansion / contraction portion, reduce the types of parts to be used, and Can be easily.

Front view showing an embodiment of the present invention 1 is an enlarged view of the main part of FIG. (A)-(d) is explanatory drawing which shows the effect | action of the same embodiment Detailed view of bent part (rotating part) Detailed view of telescopic part It is a detailed view of a detachment prevention joint part, (a) is a front view, (b) is a side view. Detailed view of telescopic part (A)-(e) is explanatory drawing which shows the construction method of a cable protection pipe

  Embodiments of the present invention will be described with reference to the drawings. This embodiment is a seismic joint structure for a cable protection tube that is supported at regular intervals by brackets installed on a main girder of a bridge girder. In order to maintain the soundness of the pipe during an earthquake, it is installed between the fulcrum part, that is, between the abutment A and the bracket B provided at the end of the girder, and follows the pipe axis direction (bridge axis direction) and eccentricity. It is set as the structure which has.

  This cable-protection tube earthquake-resistant joint structure (hereinafter simply referred to as “earthquake-resistant joint structure”) functions only in the event of a large-scale earthquake. Therefore, it is necessary to maintain a state in which performance can be exhibited when necessary. is there. Moreover, it is desirable that the structure does not affect the adjacent general pipe line due to the reaction force of expansion and contraction and eccentricity. An image of the earthquake-resistant joint structure is shown in FIG.

The required performance for the target seismic joint structure is as follows.
Diameter: φ125
Material: NFRP (flame retardant, flame proof grade 3, JIS A 1322)
Number of installations: 10 (5 rows x 2 rows)
Cable type: 400sq (occupancy rate 85%)
Cable weight: 165 N / m (16.8 kgf / m)
Watertight performance: Deformation performance not considered: Stretching performance ± 214mm
Eccentricity 163mm
Other: Compliant with FRP pipe specifications for electric power

  The main part of the structure of the earthquake-resistant joint structure based on the above points is shown in FIG. This seismic joint structure is a structure that follows expansion and contraction by the expansion / contraction part 20 provided at the center part of the abutment A and the bracket B at the end, and eccentricity by the two bending parts 10 provided at both ends in the tube axis direction. It is. Images at the time of deformation of the stretchable part 20 and the bent part 10 are shown in FIGS.

  That is, the expansion / contraction part 20 allows the sliding part 25 to expand and contract in the tube axis direction, and the bending part 10 allows bending in the direction perpendicular to the tube axis. In this embodiment, the bent portion 10 is configured to allow bending between the adjacent tubular bodies 3 and 4 by sliding the spherical surfaces 13 and 14 that are in surface contact with each other. This is referred to as a rotating unit 10.

  Moreover, the separation prevention joint 40 was installed in the both ends of the earthquake-resistant joint so that these displacements might be borne by the earthquake-resistant joint. In addition, in this configuration, since there is no restriction on rotation and expansion / contraction, it becomes difficult for the pipe line to maintain linearity at normal times. Therefore, foreign matter adheres to the sliding portion 25 as time passes. Then, considering that the performance is impaired, a rubber displacement restraining cover 30 is installed.

  The structure of the rotating unit 10 is shown in FIG. In this structure, the joint is made spherical to allow rotation and absorb angular displacement. The inner tube portion 11 and the outer tube portion 12 constituting the rotating portion 10 slide along the spherical surfaces 13 and 14 to rotate along the spherical surface.

  Reference numeral 12 a in the figure is a flange of the outer tube portion 12 constituted by the second member 4, and reference symbol 12 b is an end fixing ring for preventing the inner tube portion 11 constituted by the first member 3 from coming off. The allowable rotation angle is 12 ° (no directivity), and sealing is performed by the O-ring 12c in consideration of simple waterproofing. In addition, the inner surface shape is devised so that the protrusion does not come out and the cable is not damaged during angular displacement.

  The structure of the stretchable part 20 is shown in FIG. This structure is a slidable double tube structure, and the inner and outer tube bodies 4 and 5 move relative to each other in the tube axis direction to absorb axial displacement. That is, the sliding portion 25 is configured by sliding the inner tube portion 21 (third member 5) and the outer tube portion 22 (second member 4) constituting the expandable portion 20 in the tube axis direction.

  The sliding portion 25 is provided at the end portion on the one bent portion 10 side of the stretchable portion 20 and the end portion on the other bent portion 10 side, respectively. The inner tube portion 21 of both sliding portions 25 is composed of a single continuous straight tube 5 (the third member 5). That is, both ends of the straight pipe 5 correspond to the inner pipe portions 21 of the respective sliding portions 25.

  In the figure, reference numeral 22a denotes a flange of the outer pipe portion 22 constituted by the second member 4, and reference numeral 22b denotes an end for retaining the inner pipe portion 21 constituted by the third member 5 (the straight pipe 5). It is a part fixing ring. In consideration of simple waterproofing, sealing is performed by an O-ring 22c.

  A rubber ring 23 is provided at the end of the inner tube portion 21 of the sliding portion 25. The rubber ring 23 also serves to prevent separation from the end fixing ring 22b. That is, the rubber ring 23 has a water stopping function and a retaining function for the sliding portion 25.

  The straight pipe 5 is obtained by processing a general-purpose straight pipe of φ125. As a result, it is possible to reduce the number of special parts, thereby shortening the delivery time and reducing the cost. Moreover, each 2nd member 4 arrange | positioned at both sides is a common component, The reduction of the number of special components is aimed at also in this point.

  The structure of the separation preventing joint 40 is shown in FIG. This structure occurs between the bridge superstructure and the substructure by connecting the joint part with the FRP (FRPM) pipe of the general support section and the abutment concrete winding section (Abutment A) to the separation preventing joint 40. The structure can follow the relative displacement effectively. The details are shown in FIG.

  In the figure, reference numeral 42 a is an engagement groove of the outer tube portion 42 constituted by the fixed pipe 2, and reference numeral 42 b is a circumferential groove for accommodating the O-ring 43. The engagement grooves 42a are provided with a predetermined length in the circumferential direction, and a total of four locations are provided along the circumferential direction. Further, reference numeral 42c is an access groove provided to open at the pipe end in a part of the entire circumferential length of the engagement groove 42a.

  For joining the inner tube portion 41 constituted by the first member 3 and the outer tube portion 42 constituted by the fixed tube 2, four protrusions 41 a provided on the inner tube portion 41 in the circumferential direction are formed by the access grooves. After the insertion into the engagement groove 42a from 42c, the inner tube portion 41 is rotated by 45 ° around the tube axis, whereby the protrusion 41a moves to the inner circumferential portion of the engagement groove 42a (the portion corresponding to the direction other than the entrance / exit groove 42c). Therefore, the ability to prevent separation in the tube axis direction can be exhibited. In addition, after installation, the inner tube portion 41 and the outer tube portion 42 do not rotate and fall off during operation by inserting the pins 45 in a total of four locations along the circumferential direction from the outside toward the inside in the radial direction. Consideration is taken. In this embodiment, the pins 45 are provided at a total of four locations, but the pins 45 may be provided at least at one location.

  In this embodiment, a displacement restraining cover 30 is provided on the outer peripheral side of the stretchable part 20 including both sliding parts 25 for the purpose of preventing shape deterioration due to shape retention and foreign matter adhesion. The structure of the cover 30 is shown in FIG.

This cover 30 is a rubber cylindrical member, and inwardly-shaped annular projections 30a provided at both ends of the cylinder axis direction are fitted into the end of the flange 22a and fixed by a fixing jig 31 addressed to the outer peripheral side. , And is fixed to the flange 22a. Note that the fixing jig 31 can be omitted as necessary.
The cover 30 normally suppresses unnecessary displacement due to its own weight and vibration of the bridge due to the elasticity of the rubber. Further, when a large displacement occurs due to the earthquake, the cover 30 is broken and the original displacement tracking performance is exhibited. In addition, since the gap between the inner tube portion 21 and the outer tube portion 22 of both the sliding portions 25 is not exposed to the outside by the cover 30, entry of foreign matter into the sliding portion 25 is prevented.

  FIG. 8 shows the installation procedure of the earthquake-resistant joint structure composed of these structures. The fixed pipe 2 is assembled by laminating and joining the receiving ports of the separation preventing joints 40 at both ends to a straight pipe at the factory. The fixed tube 2 is fixed to the abutment A. Moreover, the earthquake-proof joint provided with the rotation part 10 and the expansion-contraction part 20 is assembled in a factory (refer Fig.8 (a) (b)).

  The installation of the seismic joint on site is as shown in the procedure shown in FIGS. Thus, no special work is required for installation of the earthquake-resistant joint structure, and construction can be performed with a simple tool.

  In addition, the earthquake-resistant joint structure which consists of these structures can be employ | adopted also in the underground embed | buried part besides the bridge attachment part shown to this embodiment.

1 Cable protective tube 2 Fixed tube 3 First member 4 Second member 5 Third member (straight tube)
10 Bent part (rotating part)
DESCRIPTION OF SYMBOLS 11 Inner pipe part 12 Outer pipe part 20 Expansion-contraction part 21 Inner pipe part 22 Outer pipe part 23 Rubber wheel 30 Cover 40 Detachment prevention joint 41 Inner pipe part 42 Outer pipe part

Claims (1)

The cable protection tube attached to the bridge has at least two bent portions (10) that allow bending in the tube axis direction, and the expansion and contraction that allows expansion and contraction in the tube axis direction between the two bent portions (10). Part (20), and the expansion / contraction part (20) includes a sliding part (25) in which the inner pipe part (21) and the outer pipe part (22) slide in the pipe axis direction. 25) A rubber ring (23) is provided at an end of the inner pipe part (21) or the outer pipe part (22), and the rubber ring (23) is connected to the sliding part (25). It has a water stopping function and a retaining function, and includes a detachment preventing joint (40) on the outer side in the tube axis direction of each of the two bent portions (10),
The separation preventing joint (40) includes a fixed pipe (2) fixed to the abutment (A) or the bracket (B) of the bridge girder and a first member (3) connected to the fixed pipe (2), The fixed pipe (2) is provided to open to the pipe end at a part of the engagement groove (42a) provided in a predetermined length in the circumferential direction and the circumferential length of the engagement groove (42a). An inlet / outlet groove (42c), and the first member (3) is inserted into the engaging groove (42a) from the inlet / outlet groove (42c), and the first member (3) and the fixed tube (2) Is provided with a protrusion (41a) that reaches the inner circumferential direction of the engagement groove (42a) by relatively rotating around the tube axis, and the engagement between the protrusion (41a) and the engagement groove (42a) said fixed pipe (2) the first member (3) and seismic joint structure of the cable protection tube, which is a fixable .

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