Pipe rehabilitation method

In a pipe rehabilitation method, segments are linked in the circumferential and pipe-length directions to install a rehabilitation pipe inside an existing pipe. Nuts are secured to the segments along the circumferential direction thereof. Linking members each configured to be screwed into one of the secured nuts are inserted into each segment. Each linking member is temporarily locked to the segment to prevent the inserted linking member from falling out of the segment. The segment into which the linking members are inserted and temporarily locked and one of the segments to which the nuts are secured are aligned relative one another, and the linking members are screwed into the respective nuts to fasten both segments together and link them in the pipe-length direction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pipe rehabilitation method for installing a rehabilitation pipe inside an existing pipe using segments each of which comprises an inner surface plate constituting an inner circumferential surface, and side plates and end plates provided upright on peripheral edges of the inner surface plate, these plates being formed integrally from a plastic material and linked in the circumferential direction and in the pipe-length direction.

2. Description of the Related Art

In cases in which a sewage pipe or another pipeline buried underground has deteriorated through aging, a pipe lining method has been proposed and practiced in which a lining is provided to the inner circumferential surface thereof to repair the pipeline without excavating it from the ground.

In this pipe lining method, a pipe lining material made of a tubular resin absorbent material impregnated with an uncured thermosetting resin is everted and inserted into a pipeline using fluid pressure, and is pressed by fluid pressure against the inner peripheral wall of the pipeline. The lining material is then heated using a desired method to cure the thermosetting resin therein and form a plastic pipe, thereby repairing the pipeline.

There is also known a lining method using segments each comprising an inner surface plate constituting an inner circumferential surface, side plates and end plates provided upright on the peripheral edges of the inner surface plate, these plates being integrally formed from a plastic material. The segments are linked in the circumferential direction to assemble short pipe units, which are then linked in the pipe-length direction to construct a rehabilitation pipe inside an existing pipe (for example, JP-A 2011-12803). Such a pipe rehabilitation method is used for large-diameter existing pipes. In this method, after assembling a rehabilitation pipe inside the existing pipe, grout or another filler material is injected into a space between the existing pipe and the rehabilitation pipe and hardened to construct a composite pipe.

In the rehabilitation pipe described in JP-A 2011-12803, segments are successively carried into a manhole and coupled in the circumferential direction to assemble a pipe unit. A plurality of nuts are secured to each segment of the assembled pipe unit, and the pipe units with the nuts secured thereto are brought into contact with each other. A bolt is inserted into the segment of one pipe unit and screwed into the nut secured to the segment of the other pipe unit to fasten both segments together, thus linking both pipe units in the pipe-length direction.

However, the bolts are inserted into the segment and tightened at a dark site by an operator. This makes the rehabilitation operation more complex and inefficient, necessitating time and labor.

It is therefore an object of the present invention to provide a pipe rehabilitation method that is capable of easily linking the segments in the pipe-length direction to reduce labor during pipe rehabilitation operations.

SUMMARY OF THE INVENTION

The present invention provides a pipe rehabilitation method in which segments are linked in the circumferential and pipe length directions to install a rehabilitating pipe inside an existing pipe. Each of the segments comprises an inner surface plate, side plates provided upright on both sides extending in the circumferential direction of the inner surface plate, and inner plates provided upright between the side plates. In the method, a plurality of nuts is secured to the segments along the circumferential direction thereof. A linking member that can be screwed into the nut is prepared and inserted into a segment. The segment into which the linking member is inserted and the segment to which the nut is secured are aligned, and the linking member is screwed into the nut to fasten both the segments together and link them in the pipe length direction. A temporary lock is mounted on the segment to temporarily lock the linking member to the segment and prevent the inserted linking member from falling out therefrom.

According to the present invention, the linking member for linking the segments in the pipe-length direction is temporarily locked to the segment using a temporary lock so as not to fall out therefrom. Therefore, the temporarily locked linking member is simply pushed and screwed into the nut to link both the segments in the pipe-length direction. Thus, the segments are easily linked in the pipe-length direction, saving labor during pipe rehabilitation operations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with references to embodiments illustrated in the accompanying drawings. The present invention is suitable for rehabilitating or repairing sewage pipes, water supply pipes, tunnels, agricultural irrigation channels, and other existing large-diameter pipes. In the present embodiment, the rehabilitation pipes are described as having a circular cross-section profile orthogonal to the pipe-length direction. However, it shall be apparent that the present invention can be applied to a rehabilitation pipe having a square or another non-circular cross-section. Also, in addition to structures in which the cross-section profile is closed as a pipe, a structure having a horseshoe-shaped, semi-circular, U-shaped, or another cross-section profile in which one side is open can also be considered to be a pipe, and the present invention can also be applied thereto.

In the present specifications, the pipe-length direction refers to the direction indicated by arrow X extending in the longitudinal direction of a pipe unit10inFIG. 3, the radial direction refers to the direction indicated by the radial arrow R pointing towards the center axis of the pipe unit10, and the circumferential direction refers to the direction of the circumference of the circle forming the pipe unit10.

FIG. 1shows the structure of a segment 1 for pipe rehabilitation (hereafter simply referred to as “segment”), which represents an assembly unit member of a rehabilitation pipe for rehabilitating an existing pipe. The segment 1 is an integrally formed block-shaped member made from a plastic material, comprising an inner surface plate101constituting an inner circumferential surface of the rehabilitation pipe, side plates102,103provided vertically upright on both sides extending in the circumferential direction of the inner surface plate101, and end plates104,105provided vertically upright on both ends extending in the pipe-length direction of the inner surface plate101.

In the present embodiment, the segment 1 has a shape that is curved as an arc representing a predetermined angle that equally divides the circumference, e.g., a 60° arc that divides the circumference into sixths. However, the segment is not limited to that having an arc or a fan shape. The segment may be shaped as, e.g., a cuboid or a shape that is bent so as to have a curved right angle depending on the cross-section profile or the size of the existing pipe or the location of the existing pipe to be repaired.

A plurality (four in the present embodiment) of inner plates106,107having a shape similar to that of the side plates are provided upright at equal intervals and parallel to the side plates102,103on the upper surface of the inner surface plate101and on the inside relative to the side plates102,103in order to reinforce the mechanical strength of the segment 1. One or both of the inner plates106,107can be omitted if the segment 1 has sufficient strength.

A plurality of holes102afor admitting insertion of a linking member for linking the segment 1 in the pipe-length direction are provided at equal intervals along the circumference on the lower section102eof the side plate102. The holes102ain the side plate102and holes103ain the side plate103are located at coinciding positions along the circumferential direction, allowing the linking member to be inserted through the holes102aand103ain the side plates102and103.

Openings102b,103b, used for a linking operation of the segments in the circumferential direction, are provided to the side plates102,103at both ends in the vicinity of the end plates104,105. When the segments are connected in the circumferential direction, a bolt, a nut, or another linking member is, e.g., positioned or tightened through the openings102b,103b.

The end plates104,105are disposed between the side plate102and the side plate103. The height of the end plates104,105from the outer surface of the inner surface plate101is slightly lower than that of the side plates102,103. Provided on the end plates104,105are circular insertion holes104a,105afor admitting insertion of a bolt or another linking member for linking the segment 1 in the circumferential direction.

The inner plate106is a thin-plate member having a profile substantially identical to the side plates102,103. Circular insertion holes106afor admitting insertion of linking members for linking the segments in the pipe-length direction are provided at equal intervals on the inner plate106. The positions of the insertion holes106ain the circumferential direction coincide with those of the insertion holes102aof the side plate102in the circumferential direction.

The inner plate107is a thin-plate member having a profile substantially identical to the side plates102,103, and a plurality of notches107aare provided thereon. The notches107ahave a half-moon shape in which the lower portions thereof function to admit insertion of linking members. The positions of the notches107ain the circumferential direction coincide with those of the insertion holes102a,103a,106aof the side plates102,103and the inner plate106in the circumferential direction.

The inner surface plate101, the side plates102,103, the end plates104,105, and the inner plates106,107are all made from an identical transparent, semi-transparent or opaque plastic material, and are integrally formed using a known molding technique.

FIGS. 2aand2bshow a method for linking the segments 1 in the circumferential direction. Two segments 1, 1 are held so that the end plate105of one of the segments and the end plate104of the other segment are aligned in contact with each other. A wrench or another tool, or a technician's finger, is inserted from the opening102bin the side plate102of the segment, and a bolt6is inserted into the insertion holes104a,105a. A nut7is then threadedly engaged to the bolt6, thereby fastening both end plates104,105together and linking the two segments 1, 1 in the circumferential direction.

Bolting as described above is performed in two locations, i.e., between the side plate102and the adjacent inner plate106, and between the side plate103and the adjacent inner plate106. In an instance in which the linking in two locations as described above results in insufficient linking strength, a linking member is also positioned in other insertion holes104a,105a, from above the segment, between the inner plates106,107to strengthen the linking in the circumferential direction.

By sequentially linking the segments 1 in the circumferential direction around the full circumference, it is possible to assemble a closed ring-shaped short pipe assembly10(hereafter referred to as “pipe unit”) having a predetermined small length in the pipe-length direction X as shown inFIG. 3. The pipe unit10has a shape that can be obtained when a circular pipe is sliced at a predetermined width D perpendicularly to the pipe-length direction X. The outside diameter of the pipe unit10is slightly smaller than the inside diameter of the existing pipe to be rehabilitated. The segment 1 corresponds to a member obtained by dividing the pipe unit10into a plurality of (preferably equal) portions along a cutting surface parallel to the radial direction R.

InFIG. 3, the inner surface plate101, the side plates102,103, and the end plates104,105, which are the principal structural members of the segment 1, are shown. In order to prevent the drawing from becoming complicated, the inner plates106,107and other reinforcement structures are not shown.

Each of the segments in the pipe unit10of such description is linked to a segment of another pipe unit using a linking member (tightening member)11extending in the pipe-length direction and a nut12, as shown inFIGS. 4 and 5, for extension in the pipe-length direction.

The linking member11is, as shown inFIG. 6, a metallic bolt that has at one end a screw part11ascrewed into the nut12, and at the other end a hexagonal part14with a flange14a. The linking member11is circular in cross section and has such a diameter as to be capable of passing through the insertion holes102a,103a,106a, and the notches107aof the segment. The diameter of insertion holes102a,103ais larger than that of the insertion holes106aand the notches107a, and the flange14ais shaped so as to be capable of passing through the insertion holes102a,103aof the side plates102,103, but not through the insertion holes106aand the notches107ain the internal plates106,107.

When the segments are linked in the pipe-length direction, the nut12is secured to the segment at a plurality of locations in the circumferential direction. As shown inFIG. 5a, the nut12is passed through the insertion hole102ain the side plate102of one segment 1a and brought into contact with the first inner plate106, i.e., the inner plate106positioned nearest to the side plate102. A bolt13having a screw part13aand a flange13bis inserted into the insertion hole106aof the inner plate106from the other side and threaded into the nut12. The nut12is thus fastened against the inner plate106and secured against it, as shown inFIG. 5b.

The nut12may be secured to the segment 1 after the segments are linked in the circumferential direction as shown inFIG. 3, or the segments may be linked in the circumferential direction so as to constitute the pipe unit10after the nut12is first secured to the segment 1.

As shown inFIGS. 5cand6, the linking member11is inserted into the segment 1b that is to be linked to the segment 1a to which the nut12is secured. The linking member11is temporarily locked to the segment 1b using a temporary lock50(temporary lock member) in order to prevent the inserted linking ember11from falling out from the segment 1b.

The temporary lock50is comprised of an elastic flexible sheet of plastics such as PET, polypropylene or the like. The temporary lock50comprises an integral upper sheet51and side sheets52,53that are perpendicularly provided at both ends of the upper sheet51. The width d of the upper sheet51in the pipe-length direction is substantially the same as the distance between the inner plates106,107and the height h of the side sheets52,53is substantially the same as the height H of the inner plates106,107.

Openings52a,53ahaving a diameter slightly smaller than that of the linking member11are formed at the central portion of the side sheets52,53. One or a plurality of breaks52b,53bextending radially from the center of the openings52a,53aare formed on the side sheets52,53so that the linking member11can be easily pushed and inserted into the openings52a,53a. Furthermore, notches52c,53cthat extend downwardly from the openings52a,53aare formed in the side sheets52,53. The notches52c,53care shaped so as to allow the linking member11to pass vertically therethrough for insertion into the openings52a,53aof the temporary lock50.

With such a configuration, the linking member11is inserted into the insertion holes102a,106aand the notches107aof the side plate102and the inner plates106,107of the segment 1b, and moved in the pipe-length direction until the distal end of the screw part11aof the linking member11comes near the side plate103, as shown inFIG. 5c.

In this state, the temporary lock50is brought down toward the linking member11that is located between the inner plates106,107. When the temporary lock50is brought down until the linking member11passes through the notches52c,53cand fits into the openings52a,53a, the temporary lock50is sandwiched between the inner plates106,107and remains in a state where it cannot be moved in the pipe-length direction. Since the diameter of the linking member11is larger than that of the openings52a,53a, the break portions52b,53bshift in the pipe-length direction and the openings52a,53aare so widened in diameter that the side sheets52,53come into frictional contact with the circumferential surface of the linking member11. The frictional resistance due to the frictional contact depends on the diameter of the openings52a,53aand the number of the breaks52b,53bof the temporary lock50. Accordingly, the diameter of the openings52a,53aand/or the number of the breaks52b,53bare so set that a frictional resistance is produced between the linking member11and the temporary lock50for preventing the linking member11from removing from the openings52a,53aand dropping out of the segment by its own weight.

InFIG. 6, the linking member11is first inserted into the segment and then the temporary lock50is mounted between the inner plates106,107. Alternatively, the temporary lock50may be first disposed between the inner plates106,107and then the linking member11may be inserted into the openings52a,53aof the temporary lock50to temporarily lock the linking member11to the segment.

InFIGS. 5cand6, the temporary lock50is mounted between the inner plates106,107. However, as shown inFIG. 4, the temporary lock50may be mounted between the side plate103and the inner plate106or between the inner plates107,107for temporary lock of the linking member to the segment.

As illustrated inFIG. 7, temporary locking may be performed using a temporary lock60comprised of one sheet. The temporary lock60is made from the same material as the temporary lock50, and is the same in shape as the side sheets52,53with its height h substantially the same as the height H of the inner plates106,107. The temporary lock60is provided at its center with an opening60ahaving the same shape and size as the openings52a,53aof the temporary lock50, and one or a plurality of breaks60bsimilar to the breaks52b,53bof the temporary lock50is formed, extending radially from the center of the opening60a. The temporary lock60is further provided with a vertically extending notch60csimilar to the notches52c,53c. The temporary lock60is bent at the upper portion at a right angle, and its upper portion is adhesively secured to the upper portion of the inner plate106, or the temporary lock60is fixed to the inner plate106using an adhesive sheet.

The temporary lock60has the same configuration and function as the side sheet52or53of the temporary lock50, and provides the same advantages as the side sheet52or53. The temporary lock60may be mounted not only on one inner plate, but also on another inner plate or side plate to provide an enhanced temporary lock function.

Once the linking member11has been temporarily locked to the segment 1b, the segments 1a, 1b are, as shown inFIG. 5c, aligned to each other so that the linking member11can be screwed into the nut12secured to the segment 1a. The nut12of the segment 1a is then inserted into the insertion hole103ain the side plate103of the segment 1b to place the segments 1a, 1b against each other, as shown inFIG. 5d.

The frictional resistance produced between the linking member11and the temporary lock50temporarily locks the linking member11. However, using tools or human power allows the linking member11to be moved in the pipe-length direction against the frictional resistance until it comes into contact with the nut12. Electric tools are then used to screw the linking member11into the nut12until the flange14aof the linking member11presses against the leftmost inner plate106of the segment 1b, thereby fastening and fixing the two segments 1a, 1b as shown inFIG. 5e.

FIG. 4shows a state in which the linking members11each of which is temporarily locked by the temporary lock50are screwed into the nuts12to link the segments in the pipe-length direction.

A plurality of the nuts12are fixed along the circumferential direction to each segment, the nuts12being fixed to every second hole102a, or at less regular intervals, depending on the required strength. In the example shown inFIG. 4, the segments are linked in the pipe-length direction with the nut positions in each segment being displaced in the circumferential direction relative to the nut positions in the segment adjacent to the segment in question. For example, the positions of the nuts12in the segment 1a in the center are displaced relative to the positions of the nuts12in the segments 1b, 1c adjacent to the segment 1a by an amount corresponding to the intervals between the holes102ain the side plate102as viewed in the circumferential direction. Such a linking enhances the strength of the rehabilitation pipe.

A description will now be given for a method for rehabilitating an existing pipe using the segments configured as described above.

First, as shown inFIG. 8, the segment 1 is carried through a manhole20into an existing pipe21, and as shown inFIGS. 2a,2band3, the segments are sequentially linked in the circumferential direction to assemble the pipe unit10. The nut12may be secured to the segment 1 before or after the segment 1 is carried into the manhole20, or may be secured thereto after the pipe unit10has been assembled in the manhole20.

The linking members11are temporarily locked to the segments using the temporary locks50,60that are mounted at locations at which the nuts12are secured to the segments to be linked. Such a temporary locking operation is performed before factory shipment or at a construction site on the ground, or before or after assembly of the pipe unit inside the manhole. As described above, the linking member is first inserted into the segment and then the temporary lock is mounted thereto, or the temporary lock is first mounted and then the linking member is inserted into the segment.

The pipe units with the linking members temporarily locked are successively transported into the existing pipe and linked to the pipe units already disposed in the existing pipe. Such a linking operation is performed as shown inFIGS. 4 and 5, as described above.

Thus, the pipe units10are sequentially linked in the pipe-length direction to install the rehabilitation pipe40inside the existing pipe21, as shown inFIGS. 8 and 9. InFIGS. 8 and 9, the linking members11and similar elements are not shown, and the segments are shown in a simplified manner. The temporary locks remain in the segments because it is unnecessary to remove them after installation of the rehabilitation pipe.

Next, as shown inFIG. 9, a filler material30such as a grout material or the like is injected into a space S between the rehabilitation pipe40and the existing pipe21, and the filler material is hardened. For injection of the filler material, an injection hole is formed in, e.g., the inner surface plate101, and the filler material30is injected therefrom. The injected filler material30allows the existing pipe21and the rehabilitation pipe40to be solidly bound when it is hardened, and it becomes possible to create a composite pipe comprising the existing pipe, the filler material, and the rehabilitation pipe.