Abstract:
A pipe unit for a rehabilitation pipe is used to rehabilitate an existing pipe. The pipe unit has segments mutually linked in a circumferential direction of the pipe unit, and at least one diameter expander for enlarging an inner diameter of the pipe unit. The diameter expander has a thickness in the circumferential direction of the pipe unit and is inserted between an adjacent pair of the mutually linked segments so as to be completely separated from each other by the diameter expander in the circumferential direction and by an amount corresponding to the thickness of the diameter expander.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a rehabilitation pipe for repairing pipeline facilities using segments each comprising 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, wherein the inner surface plate, the side plates, and the end plates are formed integrally from a plastic material and the segments are linked in the circumferential direction and in the pipe-length direction to construct a rehabilitation pipe inside an existing pipe. The present invention also relates to a pipe rehabilitation method using the rehabilitation pipe. 
     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 2005-264635). 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. 
     When a rehabilitation pipe is to be installed in a construction site, there may be instances in which the diameter of the rehabilitation pipe must be made slightly larger than the rated size in order to compensate errors that have arose in constructing the existing pipe or to match other structures. However, a metal mold must be newly manufactured when the size thereof is slightly modified in a method according to JP-A 2005-264635 in which the plastic segments are linked to assemble the rehabilitation pipe. This disadvantageously extends the period of the construction time and increases construction costs. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide a rehabilitation pipe and a method for rehabilitating an existing pipe in which the inside diameter of the rehabilitation pipe is made larger than the rated size speedy and cost-effectively. 
     The present invention provides a rehabilitation pipe for rehabilitating an existing pipe. The rehabilitation pipe comprises a plurality of segments each comprising an inner surface plate, and side plates and end plates provided upright on a peripheral edge of the inner surface plate, the inner surface plate, the side plates, and the end plates being formed integrally from a plastic material. The segments are linked in a circumferential direction to assemble a closed ring-shaped pipe unit and are liked in a pipe-length direction to rehabilitate the existing pipe. A diameter expander is inserted between the segments when they are linked in the circumferential direction to enlarge the diameter of the pipe unit. 
     The present invention also provides a method for rehabilitating an existing pipe. A plurality of segments is first prepared each comprising an inner surface plate, and side plates and end plates provided upright on a peripheral edge of the inner surface plate, the inner surface plate, the side plates, and the end plates being formed integrally from a plastic material. The segments are linked in a circumferential direction with a diameter expander inserted between the adjacent segments to assemble a closed ring-shaped diameter-enlarged pipe unit. The diameter-enlarged pipe units are sequentially linked in the pipe-length direction to install a segmental rehabilitation pipe inside the existing pipe. 
     According to the present invention, when the segments are linked in the circumferential direction, a diameter expander in a panel shape is provided between the segments that are adjacent in the circumferential direction, so that the rehabilitation pipe having the inside diameter larger than the rated size can be assembled speedy and cost-effectively. 
     In the invention, the end plate is provided with an opening for allowing a filler material to flow in or out that is injected into the gap between the rehabilitation pipe and the existing pipe, and the diameter expander is also provided at a position corresponding to the position of the end plate with an opening for allowing the filler material to flow in or out. This allows the filler material injected into the gap to flow in or out in the circumferential direction in a smooth manner and improves the efficiency of the linking operation and the injection operation. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and following detailed description of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing the structure of a segment used in assembling the rehabilitation pipe; 
         FIG. 2   a  is a front view of a side plate of a segment; 
         FIG. 2   b  is a cross-sectional view along line B-B in  FIG. 2   a;    
         FIG. 2   c  is a detailed view of an end plate of the segment viewed from the direction of line A-A in  FIG. 2   a;    
         FIG. 3   a  is a front view of an inner plate of the segment; 
         FIG. 3   b  is a cross-sectional view along line C-C in  FIG. 3   a;    
         FIG. 4  is a front view of another inner plate of the segment; 
         FIG. 5   a  is a cross-sectional view showing the segments linked in the circumferential direction with a bolt and a nut using a diameter expander; 
         FIG. 5   b  is a cross-sectional view showing the segments linked in the circumferential direction using a diameter expander; 
         FIG. 5   c  is a front view showing the segments linked in the circumferential direction using a diameter expander; 
         FIG. 6  is a perspective view showing a state in which the segments are linked in the circumferential direction using a diameter expander to assemble a diameter-expanded pipe unit; 
         FIG. 7  is a front view showing a state in which the segments are linked in the circumferential direction using a diameter expander to assemble a diameter-expanded pipe unit; 
         FIG. 8  is an illustrative view showing a state in which the segments of the pipe units are linked in the pipe-length direction using linking members; 
         FIG. 9   a  is a front view of a diameter expander; 
         FIG. 9   b  is a side view of a diameter expander; 
         FIG. 9   c  is a plan view of a diameter expander; 
         FIG. 10  is an illustrative view showing a state in which the pipe units are linked and the rehabilitation pipe is installed in the existing pipe; and 
         FIG. 11  is a perspective view showing a state in which the pipe units are linked and the rehabilitation pipe is installed in the existing pipe. 
         FIG. 12  is a front view showing a state in which the segments are linked in the circumferential direction using a diameter expander to assemble a diameter-expanded pipe unit having a square cross-section; 
     
    
    
     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 unit  10  in  FIG. 6 , the radial direction refers to the direction indicated by the radial arrow R pointing towards the center axis of the pipe unit  10 , and the circumferential direction refers to the direction of the circumference of the circle forming the pipe unit  10 . 
       FIG. 1  shows 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 plate  101  constituting an inner circumferential surface of the rehabilitation pipe, side plates  102 ,  103  provided vertically upright on both sides extending in the circumferential direction of the inner surface plate  101 , and end plates  104 ,  105  provided vertically upright on both ends extending in the pipe-length direction of the inner surface plate  101 . 
     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 plates  106 ,  107  having a shape similar to that of the side plates are provided upright at equal intervals and parallel to the side plates  102 ,  103  on the upper surface of the inner surface plate  101  and on the inside relative to the side plates  102 ,  103  in order to reinforce the mechanical strength of the segment  1 . One or both of the inner plates  106 ,  107  can be omitted if the segment  1  has sufficient strength. 
     The inner surface plate  101 , the side plates  102 ,  103 , the end plates  104 ,  105 , and the inner plates  106 ,  107  are all made from an identical transparent, semi-transparent or opaque plastic material, and are integrally formed using a known molding technique. 
       FIG. 2   a  is a detailed view of the side plates  102 ,  103 , and  FIG. 2   b  is a cross-sectional view along the line B-B in  FIG. 2   a . The following descriptions are given in relation to the side plate  102 , but the side plate  103  has a configuration similar to that of the side plate  102 . 
     The side plate  102  is an arc-shaped thin-plate member, and an upper section  102   d  has a smaller plate thickness than that of a lower section  102   e . This is in order to form a gap on the upper part of the two side plates  102 ,  103  when one segment is liked to another segment adjacent in the pipe-length direction, and to guide and accommodate earth and other material entering from the exterior. 
     A plurality of holes  102   a  for 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 section  102   e  of the side plate  102 . The holes  102   a  in the side plate  102  and holes  103   a  in the side plate  103  are located at coinciding positions along the circumferential direction, allowing the linking member to be inserted through the holes  102   a  and  103   a  in the side plates  102  and  103 . 
     An opening  102   b , used for a linking operation of the segments in the circumferential direction, is provided to the side plate  102  in the vicinity of both ends in the circumferential direction, i.e., at both ends in the vicinity of the end plates  104 ,  105 . Each of the openings  102   b  has a rectangular shape in which corners are chamfered. A lower edge of the opening  102   b  substantially coincides with a lower edge of the side plate  102 , and an upper edge of the opening  102   b  is somewhat lower than an upper edge of the side plate  102 . 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 opening  102   b  (see also  FIG. 5   c ). 
     The opening  102   b  is configured so that a filler material injected into a space between the existing pipe and the segmental rehabilitation pipe can flow in or out through the opening  102   b , and so that during injection, the filler material can pass through the opening  102   b  in a smooth and speedy manner. It is also possible to provide the openings  102   b ,  103   b  to the vicinity of the end plate  104  only or to the vicinity of the end plate  105  only. 
     Notches  102   c  for allowing the filler material to flow in or out and pass therethrough are provided to an upper section of the side plate  102 . The notches  102   c  have a half-moon shape in which the upper end is open. The notches  102   c  are positioned in the circumferential direction so as to be displaced from the positions of the holes  102   a  in the circumferential direction. More specifically, a notch  102   c  is provided between the hole  102   a  nearest to the end plates  104 ,  105  and the next hole  102   a , and then provided every two holes  102   a . Thus, a total of seven notches  102   c  are provided to the side plate  102 . 
       FIG. 2   c  is a detailed view of the end plate  105  as viewed from line A-A in  FIG. 2   a . The following descriptions are given in relation to the end plate  105 , but the end plate  104  has a configuration similar to that of the end plate  105 . 
     The end plate  105  is a rectangular thin-plate member arranged between the side plate  102  and the side plate  103 . The height of the end plate  105  from the outer surface of the inner surface plate  101  is slightly lower than that of the side plates  102 ,  103 . Circular insertion holes  105   a  for admitting insertion of a bolt or another linking member for linking the segment  1  in the circumferential direction are provided on the end plate  105  between the side plate  102  and an inner plate  106 , between the inner plate  106  and an inner plate  107 , between the two inner plates  107 , between the inner plate  107  and an inner plate  106 , and between the inner plate  106  and the side plate  103 . 
     A concave section  101   a  and a convex section  101   b  are provided to the inner surface plate  101  along the entire length of the circumferential direction on one end thereof in the pipe-length direction (right end in  FIG. 2   c ). A convex section  101   c  and a concave section  101   d  are provided on the other end so that the convex/concave relationship is inverted. As a result, when the segments are linked in the pipe-length direction, the concave and convex sections of segments that are adjacent in the pipe-length direction engage with each other and fulfill the function of guiding or positioning of the segments. This facilitates the operation of linking the segments in the pipe-length direction. 
     A rectangular opening  105   d  for allowing the filler material to flow in or out and pass therethrough is provided to both sides of the inner plates  107 , both sides of the inner plates  106 , and the inside of the side plates  102 ,  103  at the lower end of the end plate  105 . 
     A convex section  105   c  is provided on the end plate  105  at a position at which it intersects the inner plate  107 , and is fitted into a concave section  104   c  provided to the corresponding position on the end plate  104  that is adjacent in the circumferential direction (see also  FIG. 5   b ). 
       FIG. 3   a  is a detailed view of the inner plate  106 , and  FIG. 3   b  is a cross-sectional view along the line C-C in  FIG. 3   a . Each of the inner plates  106  is a thin-plate member having a profile substantially identical to the side plates  102 ,  103 . Circular holes  106   a  for admitting insertion of linking members for linking the segments in the pipe-length direction are provided at equal intervals to a lower section of the inner plate  106 . The positions of the holes  106   a  in the circumferential direction coincide with those of the holes  102   a  of the side plate  102 . As shown in  FIG. 3   b , the diameter of each of the holes  106   a  increases from the vicinity of the center of the plate thickness of the inner plate  106  towards the outside (i.e., the side towards the side plate). 
     Notches  106   b  for allowing the filler material to flow in or out and pass therethrough are provided to the upper section of the inner plate  106 . The notches  106   b  have a half-moon shape in which the upper end is open. The positions of the notches  106   b  are different in the circumferential direction from those of the holes  102   a ,  106   a . More specifically, a notch  106   b  is provided further towards the end plate than the hole  106   a  nearest to the end plates  104 ,  105 , and are provided every two holes  106   a . Thus, a total of eight notches  106   b  are provided. Therefore, the positions of the notches  106   b  in the circumferential direction are displaced from those of the notches  102   c  of the side plate  102  by an amount equivalent to the intervals between the holes  106   a  in the circumferential direction. The notches  106   b  and the notches  102   c  are thus in a staggered arrangement when the segment is viewed from above. This also applies to the notches  103   c  provided to the side plate  103  for passing the filler material, and to the notches  106   b  formed on the inner plate  106  adjacent to the side plate  103 . 
       FIG. 4  is a detailed view of the inner plate  107 . The inner plate  107  is a thin-plate member having a profile that substantially coincides with the side plates  102 ,  103 . A plurality of notches  107   a  is provided from the vicinity of the lower end towards the upper end of the inner plate  107 . The positions of the notches  107   a  in the circumferential direction coincide at the lower section thereof with those of the holes  102   a  in the side plate  102  and the holes  106   a  in the inner plate  106 . The notch  107   a  at the center of the segment  1  is perpendicular to the inner surface plate  101 , and the other notches  107   a  are oriented so as to be parallel to the notch  107   a  in the center. Such an arrangement facilitates removal from the mold when the segment is integrally formed. 
       FIGS. 5   a ,  5   b , and  5   c  show a method for linking the segments  1  in the circumferential direction. Two segments  1 ,  1  are held so that the end plate  105  of one of the segments and the end plate  104  of the other segment are positioned with a diameter expander  120  inserted therebetween. A wrench or another tool, or a technician&#39;s finger, is inserted from the opening  102   b  in the side plate  102  of the segment, and a bolt  6  is inserted into the insertion holes  104   a ,  105   a . A nut  7  is then threadedly engaged to the bolt  6 , thereby tightening both end plates  104 ,  105  and the diameter expander  120  and linking the two segments  1 ,  1  in the circumferential direction with the diameter expander  120  therebetween. The concave section  104   c  and convex section  105   c  that fit into the concave section  104   c  are formed on the end plate  104  and the end plate  105  at a position at which they intersect with the inner plate  107 . As shown in  FIG. 9   b , the diameter expander  120  has a convex section  120   c  that fits into the concave section  104   c  of the end plate  104 , and has a concave section  120   b  into which the convex section  105   c  of the end plate  105  fits (see  FIG. 5   b ). 
     A concave section  104   e  and a convex section  104   f  are formed along the entire length in the pipe-length direction on a lower end of the end plate  104 . A convex section  105   f  and a concave section  105   e  that fit with the concave section  104   e  and the convex section  104   f  are formed along the entire length in the pipe-length direction on a lower end of the end plate  105 . These convexes and concaves are configured so as to fit concaves  120   e  and  120   h  and convexes  120   f  and  120   g  that are formed at the lower end of the diameter expander  120  (see  FIG. 9   b ). Such an arrangement facilitates the task of positioning the two segments  1  and bringing the two segments in close contact with the diameter expander  120  when the segments are linked in the circumferential direction. Also, applying a sealing material (not shown) to the fitting section makes it possible to enhance the water-tightness of the linking section. Bolting as described above is performed in two locations, i.e., between the side plate  102  and the adjacent inner plate  106 , and between the side plate  103  and the adjacent inner plate  106 . 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 holes  104   a ,  105   a ,  120   a  from above the segment, between the inner plates  106 ,  107  to strengthen the linking in the circumferential direction. 
     In  FIG. 5   a , one bolt/nut set is used per location. However, in an instance in which the end plates  104 ,  105  have a large height because of segments used for large-diameter existing pipes, the segments can be linked in the circumferential direction using two or more bolt/nut sets per location. 
     The segments are thus linked in the circumferential direction through the openings  102   b ,  103   b  provided to the side plates  102 ,  103 . When the segments are linked in the pipe-length direction so that the opening  102   b  of the segment is in alignment with the opening  103   b  of the adjacent segment and both the segments come in close contact with each other, each set of the openings  102   b ,  103   b  forms a single integral opening. Therefore, when the filler material is injected into the spacing between the existing pipe and the rehabilitation pipe after installation of the rehabilitation pipe, the filler flows in or out through the integrated openings  102   b ,  103   b  without flowing downwards towards the interior of the rehabilitation pipe. Therefore, there is no need to block the openings  102   b ,  103   b , and linking in the circumferential direction can be performed in a simpler manner compared to an instance in which an opening is provided to the inner surface plate  101 . 
     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 assembly  10  (hereafter referred to as “pipe unit”) having a predetermined small length in the pipe-length direction X as shown in  FIG. 6 . The pipe unit  10  has 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 unit  10  is 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 unit  10  into a plurality of (preferably equal) portions along a cutting surface parallel to the radial direction R. 
     The diameter expander  120  is inserted between the segments  1 , so that the inside diameter of the pipe unit  10  is enlarged by an amount of thickness of the expander  120 . For example, assuming that the thickness of the diameter expander  120  be 8 mm, the inside diameter of the pipe unit  10  is made 8×6/π=15 mm larger than without the diameter expander. In  FIG. 6 , the diameter expanders  120  are used at all the liking locations in the circumferential direction, but it may be acceptable that they are used only at some locations. 
     In  FIG. 6 , the inner surface plate  101 , the side plates  102 ,  103 , and the end plates  104 ,  105 , which are the principal structural members of the segment  1 , are shown. In order to prevent the drawing from becoming complicated, the inner plates  106 ,  107  and other reinforcement structures are not shown. 
       FIG. 7  is a front view showing a state in which the segments are linked in the circumferential direction using a diameter expander to assemble a diameter-expanded pipe unit. The pipe unit is substantially circular in cross-section and slightly bent at locations at which the diameter expanders  120  are inserted, but no practical problems arise because the diameter expander  120  is sufficiently smaller in length in the circumferential direction than the segments  1 . 
     Each of the segments in the pipe unit  10  of such description is linked to a segment of another pipe unit using a linking member (tightening member)  11  and a nut  12  as shown in  FIG. 8  for extension in the pipe-length direction. 
     The nut  12  is passed through a hole  102   a  in the side plate  102  of one segment  1   a  and brought into contact with the first inner plate  106 , i.e., the inner plate  106  positioned nearest to the side plate  102 . A bolt  13  is threaded into the nut  12 , and the nut  12  is tightened against the inner plate  106  and fixed against it. 
     The length of the nut  12  in the pipe-length direction is slightly greater than the spacing between the side plate  102  and the inner plate  106 , and is such that the nut  12  protrudes outwards from the side plate  102  of the segment  1   a  when positioned as above. The amount of protrusion is equivalent to or greater than the thickness of the side plate  103  of the other segment  1   b . Therefore, the nut  12  is passed through the hole  103   a  in the side plate  103  of the other segment  1   b , and the two segments  1   a ,  1   b  are placed against each other. 
     In this state, a linking member  11  is passed through a hole  102   a  in the side plate  102 , a hole  106   a  in the inner plate  106 , and a notch  107   a  in the inner plate  107  of the segment  1   b , and a threaded section  11   b  of the linking member  11  is threaded into the nut  12  to link the linking member  11  and the nut  12 . The linking member  11  is further threaded into the nut  12  until a flange section  14   a  of a head section  14  presses against the leftmost inner plate  106  of the segment  1   b  to tighten and fix the two segments  1   a ,  1   b.    
     A plurality of the nuts  12  are fixed along the circumferential direction to each segment, the nuts  12  being fixed to every second hole  102   a , or at less regular intervals, depending on the required strength. 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, in the example shown in  FIG. 8 , the positions of the nuts  12  in the segment  1   a  in the center is displaced relative to the positions of the nuts  12  in the segment  1   c  adjacent to the right side of the segment  1   a  by an amount corresponding to the intervals between the holes  102   a  in the side plate  102  as viewed in the circumferential direction. 
     Thus, the segments of the pipe unit are linked in the pipe-length direction to the segments of another pipe unit, whereby it is possible to link the pipe units in the pipe-length direction to a desired length, and to create a rehabilitation pipe comprising the pipe units or the segments. 
       FIGS. 9   a - 9   c  are front, side and plan views of the diameter expander  120 . The diameter expander  120  is made from the same plastic material as the segment  1 , and is formed similarly thereto using a known molding technique. 
     The diameter expander  120  has a height indicated by h in  FIG. 9   a , and is sufficiently smaller in thickness b than the circumferential length of the pipe unit  10 . 
     The diameter expander  120  is provided at its upper portion with protrusions  122 ,  126 ,  127  and  123 , whose position respectively coincides with that of the side plate  102 , the inner plates  106 ,  107 , and the side plate  103  in the pipe-length direction, and whose thickness is the same as that of the side plate  102 , the inner plates  106 ,  107 , and the side plate  103 , respectively (also see  FIG. 8 ). 
     The diameter expander  120  is also provided at its upper portion with five circular insertion holes  120   a  and at its lower portion with ten rectangular openings  120   d . The diameter expander  120  is set between two segments so that the positions of the holes  120   a  respectively coincide with those of the holes  104   a ,  105   a  of the end plates  104 ,  105 , and the positions of the openings  120   d  with those of the openings  104   d ,  105   d.    
     The diameter expander  120  has two concave sections  120   b  formed at the position of the protrusion  127  and at a surface at which the end plate  105  contacts therewith when the diameter expander  120  is set, and also has two convex sections  120   c  at a surface at which the end plate  104  contacts. The diameter expander  120  also has a concave section  120   e  and a convex section  120   f  at its lower portion and at a surface at which the end plate  105  contacts therewith when the diameter expander  120  is set, and has a convex section  120   g  and a concave section  120   h  at a surface at which the end plate  104  contacts. The concave and convex sections of the diameter expander  120  are configured so as to be similar to those of the concave and convex sections of the end plates  104 ,  105  (also see  FIG. 5 ). 
     A description will now be given for a method for rehabilitating an existing pipe using the segments configured as described above. 
     First, as shown in  FIG. 10 , the segment  1  is carried through a manhole  20  into an existing pipe  21 , and as shown in  FIGS. 5 and 6 , the segments  1  are sequentially linked in the circumferential direction to assemble the diameter-enlarged pipe unit  10 . 
     Next, the pipe units  10  are sequentially linked in the pipe-length direction via the linking members  11  using the method shown in  FIG. 8 , and as shown in  FIGS. 10 and 11 , the diameter-enlarged rehabilitation pipe  40  is installed in the existing pipe  21 . In  FIGS. 10 and 11 , the linking members  11  and similar elements are not shown, and the segments are shown in a simplified manner. 
     If the diameter of the rehabilitation pipe is large, the segments  1  that have been carried in can be transported to the location of actual installation, and the segments are linked in the circumferential direction and the pipe-length direction at this location. In such an instance, there may be instances in which the gap between the outside of the segments and the existing pipe is narrow when linking the segments in the circumferential direction. This may obstruct the mounting of bolt-and-nut sets from the outside of the segment; the benefit of providing the side plates with openings for linking the segments in the circumferential direction is particularly high. 
     Next, as shown in  FIG. 11 , a grout material or another filler material  30  is injected into a space S between the rehabilitation pipe  40  and the existing pipe  21 , and the filler material is hardened. Both end sections of the space S are blocked using a resin pate, mortar, or another sealing agent. For injection of the filler material, an injection hole is formed in, e.g., the inner surface plate  101 , and the filler material  30  is injected therefrom. Injection is performed until the filler material  30  has reached the entirety of the rehabilitation pipe and has started to flow out from the side plates of segments on both ends in the pipe-length direction. During injection, the filler material  30  don&#39;t flow out from the openings  102   b ,  103   b  of the side plates  102 ,  103  into the inside of the rehabilitation pipe  40 . Such openings, therefore, improve the efficiency of the linking operation and the injection operation. 
     Since the notches  102   c ,  103   c ,  106   b  are respectively provided to the side plates  102 ,  103  and the inner plate  106  of the segment  1 , the filler material can flow smoothly in the pipe-length direction even if the space S is small or if an obstacle is present in the space S. Also, since the notches  102   c ,  103   c  formed in the side plate  102  or  103  and the notches  106   b  formed in the adjacent inner plate  106  are staggered when the segment is viewed from above (outside), the filler material is injected in a zigzag shape, thus allowing the filler material to be injected in a uniform manner. 
     The height of the end plates  104 ,  105  and the diameter expander  120  is smaller than the height of the side plates  102 ,  103  and the inner plates  106 ,  107 , as shown in  FIG. 5   c , and there is a significant gap between the upper end of the end plates  104 ,  105  and the existing pipe  21 ; therefore, the filler material can also flow smoothly in the circumferential direction. 
     The openings  104   d ,  105   d ,  120   d  provided to the lower section of the end plates  104 ,  105  and the diameter expander  120  not only allow the filler material to flow in or flow out and pass through because they are all in alignment, but also function as a passage for air between the existing pipe  21  and the inner surface plate  101  pushed out when injecting the filler material, therefore allowing the filler material to flow in an even smoother manner. 
     The injected filler material  30  allows the existing pipe  21  and the diameter-enlarged rehabilitation pipe  40  to 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. 
     Next, another embodiment will be described in which the invention is applied to a pipeline of a square cross-section.  FIG. 12  is a front view showing a state in which the segments are linked in the circumferential direction using a diameter expander to assemble a diameter-expanded pipe unit  20  of a square cross-section. The pipe unit  20  comprises four L-shaped segments  2  and four straight segments  3 . Eight diameter expanders  130  are inserted between the segments  2 ,  3  to make the diameter of the pipe unit  20  larger than without the diameter expander  130 . In this embodiment, the segments  2 ,  3  are linked via the diameter expanders  130  straightforwardly in the circumferential direction, so that no distortion arises in a cross-sectional shape. Therefore, a ratio of the thickness of the diameter expander to the circumferential length is made larger than in the first embodiment. 
     The segments  2 ,  3  have a structure similar to that of the segment  1  and is made from the same material as the segment  1 , so that detailed explanation will be omitted. The diameter expander  130  corresponds in shape to the end plates of the segments  2 ,  3 , as is the case with the diameter expander  120  as shown in  FIGS. 9   a - 9   c.