Abstract:
Segments are successively coupled in the circumferential direction and the vertical direction to provide a rehabilitating pipe that rehabilitates an exiting pipe such as a manhole extending in the vertical direction. The segments are coupled in the vertical direction by stacking segments on previously assembled segments. A gap between the existing pipe and the rehabilitating pipe is filled with a filler after completion of the assembly as a rehabilitating pipe. The filler is hardened to integrate the rehabilitating pipe with the existing pipe as a compound pipe. With such an arrangement, the rehabilitating pipe can be laid by a simple method because the segments can be stacked on previously assembled segments using the segments&#39; own weight.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a method for rehabilitating an existing pipe, and more specifically to a method for rehabilitating an existing pipe, wherein segments are coupled in circumferential and vertical directions, and laid as a rehabilitating pipe inside the vertically extending existing pipe, such as a manhole. 
   2. Description of the Prior Art 
   A method of rehabilitating a vertically extending existing pipe, such as a manhole, is known from Japanese Patent Laid Open Publication No. 1996-150659. This discloses a method that rehabilitates a manhole by lining the inner circumferential surface of the manhole by inserting into the manhole a lining material comprising a pipe shaped flexible resin absorbing material impregnated with a liquid setting resin. The lining material is pressed against the inner circumferential surface of the manhole by the pressure of a fluid, such as water, so that it takes a shape identical to the inner circumferential surface of the manhole. The setting resin is then cured to provide a rehabilitating pipe for the manhole. 
   In such a method, the lining material is inserted into the manhole, extending across the entire length thereof and the inner surface of the manhole is lined all at once; therefore, although the lining can be completed in a short period of time, there is a disadvantage in that the rehabilitation work cannot be carried out while viewing the appearance of the inner wall surface of the manhole and repetitively performing partial repairs. 
   Japanese Patent Laid Open Publication No. 2003-286742 discloses a method that rehabilitates an existing pipe by successively coupling segments in the circumferential direction and in the pipe longitudinal direction. One segment comprises two side plates and two end plates that are integrally provided upright at a prescribed height on an inner plate. In this method, the entirety can be repaired while performing partial repairs, but there is the disadvantage in that all segments must be coupled during assembly in the circumferential direction and in the pipe longitudinal direction using a coupling means, thereby complicating the pipe laying. 
   It is therefore an object of the present invention to provide a method for rehabilitating a vertically extending existing pipe such as a manhole, enabling, with a simple constitution, the successive repair of the existing pipe while viewing the state of an inner wall surface thereof. 
   SUMMARY OF THE INVENTION 
   According to the present invention, a method for rehabilitating an existing pipe that extends in the vertical direction, comprises preparing segments each of which is integrally formed of plastic from an inner plate having an inner surface that is flat or curved with a prescribed curvature, two side plates provided upright on each side edge of the inner plate, and two end plates provided upright on each end edge of the inner plate; successively coupling the segments in the circumferential direction and in the vertical direction, the segments being coupled in the vertical direction by stacking a segment on an underlying segment; and filling, after assembly as a rehabilitating pipe, a gap between the existing pipe and the rehabilitating pipe with a filler for integration with the existing pipe. 
   The present invention can assemble a rehabilitating pipe by using the weight of the segments themselves and stacking each segment on an already assembled segment, and can therefore reliably rehabilitate an existing pipe with a simple method. 
   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 partially and schematically showing a parallelepipedic segment 
       FIG. 2  is a perspective view partially and schematically showing a bent segment. 
       FIG. 3  is a longitudinal cross-sectional view showing the vicinity of the manhole when segments are coupled in the circumferential direction. 
       FIG. 4  is a cross-sectional view taken along the line  4 — 4  in  FIG. 3 . 
       FIG. 5  is a cross-sectional view along the circumferential direction of the coupling portion that shows a state wherein the segments are mutually coupled in the circumferential direction. 
       FIG. 6  is a perspective view that depicts a pipe unit obtained when the segments are coupled in the circumferential direction. 
       FIG. 7  is a cross-sectional view along the vertical direction that depicts a state wherein the segments are mutually coupled in the vertical direction by coupling members. 
       FIG. 8  is a cross-sectional view along the vertical direction that depicts a state wherein the segments are mutually positioned by the positioning members and coupled in the vertical direction. 
       FIG. 9  is a longitudinal cross-sectional view showing the vicinity of the manhole when the segments are coupled as the rehabilitating pipe. 
       FIG. 10  is a cross-sectional view taken along the line  10 — 10  in  FIG. 9 . 
       FIG. 11  is a cross-sectional view taken along the line  11 — 11  in  FIG. 9 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention will be described based on preferred embodiments, referring to the attached drawings. 
   Although a method that repairs or rehabilitates a manhole is explained herein, the present invention is not limited to a manhole, and can also be applied in cases wherein a pipe extends in a direction perpendicular (vertical direction) to the ground. In addition, although the explanation is for a case wherein the cross-sectional shape orthogonal to the vertical direction of the manhole is rectangular, it is understood that the present invention can also be applied to a manhole having a circular cross-sectional shape. 
   The manhole is rehabilitated by coupling segments in the circumferential direction (direction level with the ground) and in the vertical direction orthogonal to the circumferential direction One segment is as shown in  FIG. 1  and  FIG. 2  and serves as a rehabilitating or repairing member. 
   The segment  1  shown in  FIG. 1  is formed as a rectangular parallelepiped block, wherein an inner plate  101 , side plates  102 ,  103 , end plates  104 ,  105 , and a plurality of reinforcing plates  106  are integrally molded from a transparent, semitransparent, or opaque plastic. Vinyl chloride, ABS, DuraStar polymer (trade name), and the like are used as the transparent plastic. PVC, polyethylene, and the like are used as the semitransparent plastic. PVC, polyester, ABS, polyethylene, polypropylene, and the like are used as the opaque plastic. 
   The inner plate  101  is formed as a flat plate having a flat inner surface of a prescribed width and a prescribed length, and the inner surface thereof forms the inner wall surface of the rehabilitating pipe assembled. A plurality of rectangular openings  101   a  is formed respectively on each of both end parts of the inner plate  101  for performing from the inside the work in order to mutually couple the segments  1  in the circumferential direction. 
   The side plates  102 ,  103  are provided upright at a prescribed height on both side edge parts of the upper surface of the inner plate  101 . A plurality of through holes  102   a ,  103   a  (herein,  14 ) is formed respectively in the side plates  102 ,  103  at a prescribed interval for passing therethrough coupling members to couple the segments in the vertical direction (pipe longitudinal direction), as is discussed later. 
   The end plates  104 ,  105  are provided upright at both end edge parts on the upper surface of the inner plate  101  at a height the same as the side plates. Through holes  104   a ,  105   a  are respectively formed at a plurality of locations in the end plates  104 ,  105  for inserting therethrough bolts that mutually couple the segments  1  in the circumferential direction. 
   The reinforcing plates  106  reinforce the mechanical strength of the entire segment  1 , and extend at a prescribed height in a direction orthogonal to the surface of the inner plate  101  on the inner side of the side plates  102 ,  103 . The length of each reinforcing plate  106  is the same as the height of the side plates and the end plates, but some reinforcing plates can be made shorter than that. In addition, a plurality of through holes  106   a  is formed in the reinforcing plates  106 , for inserting the coupling members therethrough in the vertical direction, at a position corresponding to each of the aligned through holes  102   a ,  103   a  of the respective side plates  102 ,  103 . In addition, although not illustrated in  FIG. 1 , a plurality of protruding plates having a rib structure that protrudes in the lateral direction is formed on the inner surfaces of the side plates  102 ,  103  and on both side surfaces of the reinforcing plates  106  to enhance the strength of the segment  1 . 
     FIG. 2  shows a segment  2  that is arranged at a corner of the manhole. The basic constitution is the same as the segment  1  in  FIG. 1 , comprising an inner plate  201 , side plates  202 ,  203 , end plates  204 ,  205 , and a plurality of reinforcing plates  206  respectively corresponding to the inner plate  101 , the side plates  102 ,  103 , the end plates  104 ,  105 , and the reinforcing plates  106  of the segment  1 ; further, the respective inner plate, all of the side plates, all of the end plates, and all of the reinforcing plates are integrally formed, and are of the same material as the segment  1 . 
   In contrast to the segment  1 , which is a block that extends linearly, the segment  2  is a block that is bent at an angle of 90°, e.g., a side plate  202  has a long linear part  202   b , is then bent at approximately 45° at a bent part  202   c , continues as a linear part  202   d , is then bent at approximately 45° in the same direction at a bent part  202   e , and then continues as a short linear part  202   f . Accordingly, the angle formed by the directions in which the linear parts  202   b  and  202   f  extend is a right angle. Another side plate  203 , the inner plate  201 , and the reinforcing plates  206  are also bent corresponding thereto, and their entirety forms a bent structure. Openings  201   a  for performing the work of respectively coupling the segments in the circumferential direction are formed at both end parts of the inner plate  201 , and through holes  202   a ,  203   a  for inserting therethrough coupling members in the vertical direction are formed in the respective side plates  202 ,  203 ; in addition, through holes  204   a ,  205   a  for inserting therethrough bolts that couple the segments in the circumferential direction are respectively formed in the end plates  204 ,  205 , the same as the segment  1 . 
   The segment positioned at the corner of the manhole can also be an arcuately shaped member, instead of the shape shown in  FIG. 2 . Such a segment is obtained when a circular pipe is sliced at a prescribed width perpendicular to the pipe longitudinal direction, and the sliced pipe is then partitioned in the circumferential direction in equal parts. 
   When the segments  1  and  2  are successively coupled in the circumferential direction in end-to-end relation with the end plates of the segments mutually aligned and the inner surfaces of every inner plate aligned, a short pipe unit can be assembled having a prescribed length, closed in the circumferential direction. The segments are further coupled successively in the pipe longitudinal direction to assemble a rehabilitating pipe with its inner wall surface uniform without any gap. 
   The following explains a method of rehabilitating a manhole, using the abovementioned segments. 
   As shown in  FIG. 3  and  FIG. 4 , the segments  1 ,  2  are carried via a vertical hole  4  into a manhole  5  that communicates with main pipes  6 ,  6 ′ and whose horizontal cross sectional shape is rectangular. Inside the manhole  5 , the segments are coupled in the circumferential direction. At this time, the bent segments  2  are arranged at the four corners of the manhole  5 , and each of the bent segments  2  is coupled with a parallelepipedic segment  1 . 
   This circumferential coupling is performed by, as shown in  FIG. 5 , tightly sealing the outer surfaces of the two end plates  104  and  204  of the respective segments  1  and  2 ; positioning so that the inner surfaces of the inner plates  101  and  102  form the same surface and so that the outer surfaces of all the side plates  102 ,  103  and  202 ,  203  align; inserting bolts  16  into the through holes  104   a ,  204   a  from the openings  101   a  in the inner plate  101  of the segment  1 ; screwing on nuts  17  inserted from the openings  201   a  in the inner plate  201  of the segment  2 ; and tightening both end plates  104 ,  204 . When this coupling is completed, each of the openings  101   a ,  201   a  is tightly sealed by a cover (not shown) and the like. 
   The segments are thus coupled in the circumferential direction without any gaps to provide a closed short pipe unit. The thus assembled pipe unit has a shape sliced perpendicular to the vertical direction, as shown in  FIG. 6 . 
   The closed pipe unit as shown in  FIG. 6  constitutes the lowest level of the rehabilitating pipe, and segments are coupled in the vertical direction by successively stacking segments on top of it to form the rehabilitating pipe. If the pipe unit existing at this lowest level is not horizontal, then it can be leveled using a spacer and the like. 
   For vertical direction assembly, there are a method that uses coupling members, a method that stacks all of the segments using positioning members, and a method that uses both of these methods. 
   The method of using the coupling members is performed by using coupling members  11  made of metal and that each integrally joins a rod  11   b with both ends, one end comprising a screw part  11   a , and the other end comprising a nut part  11   c  wherein a screw hole  11   d  is formed into which the screw part  11   a  is screwed, as shown in  FIG. 7 . 
   In  FIG. 7 , the lower coupling member  11  is already joined to another coupling member  12 , and is fixed to the lower segment  1 . In this state, to couple another upper segment  1  to this lower segment  1  in the vertical direction, the surfaces of the side plates  102  and  103  of both segments  1 ,  1  are first tightly sealed with the inner surfaces of all the inner plates  101  aligned so that they are continuous and form a uniform surface. The nut part  11   c  protruding from the side plates  102  of the lower segment  1  is inserted into through holes  103   a  in the side plates  103  of the upper segment  1 . An upper coupling member  11  is then inserted through from the through hole  102   a  of the side plate  102  of the upper segment  1 , and the screw part  11   a  thereof is screwed into the screw hole  11   d  of the nut part  11   c  of the lower coupling member  11 . When the nut part  11   c  of the upper coupling member  11  makes contact with the reinforcing plate  106  of the upper segment  1 , the upper coupling member  11  clamps the upper segment  1  against the lower segment  1 , thereby causing the upper and lower segments to be fixedly coupled. Because the coupling of every segment is performed using four coupling members per segment, the upper and lower segments are coupled rigidly in the vertical direction. 
   Furthermore, if the lower segment  1  is the lowest one in  FIG. 7 , then, as shown by a virtual line  12 , the screw part that screws to the screw part  11   a  of the coupling member is fixed beforehand to the side plate  103  by some method. 
   Such circumferential and vertical coupling of the segments inside the manhole  5  is repeated until the coupled segments constitute a rehabilitating pipe of a desired height in the manhole  5 . 
   As shown in  FIG. 8 , a segment can also be stacked, utilizing its own weight, in the vertical direction on a segment using positioning members. A positioning member  13  used in this method is made of plastic and comprises a cylinder part  13   a  and a conical cylinder part  13   b  continuous thereto; the cylinder part  13   a  has a diameter slightly less than a through hole  102   a  of the side plate  102  so that it is inserted thereto and tightly interfitted; and the length of the entire positioning member is such that the upper part of the cylinder part  13   a  and the conical cylinder part  13   b  protrude from the side plate  102  when the positioning member  13  is inserted until it contacts the reinforcing plate  106 . 
   The coupling in the vertical direction is performed by first installing the positioning member  13  by inserting the positioning member  13  into the through hole  102   a  of the side plate  102  of the already installed lower (underlying) segment  1 . Thus, a plurality of positioning members  13 , preferably two to four, is used per segment. Assuming that the lower segment  1  shown in  FIG. 8  is a segment already installed as a pipe in the manhole, the positioning members  13  are installed in this segment  1 , and the upper and lower segments are mutually positioned so that the conical cylinder parts  13   b  protruding from the side plate  102  of the lower segment are inserted into the aligned through holes  103   a  of the lower side plate  103  of the other upper (overlying) segment  1 . 
   Thus, the segments can be successively stacked on the lower level segments to provide the next pipe unit lying on the lowest pipe unit. Such processes are repeated until a rehabilitating pipe with a desired height is laid. This enables a rehabilitating pipe to be constructed with a low cost in a short period of time because no coupling member as shown in  FIG. 7  is needed to couple the segments in the vertical direction. 
   Furthermore, it is also acceptable to make the positioning member so that it is integrally formed with the segment and not separate from the segment; in that case, it can be constituted so that, e.g., a positioning member having a shape that protrudes from the side plate  102  is integrally formed with the side plate. 
   In addition, instead of just simply stacking the segments, it is also acceptable to make it so that, after stacking, a stacked segment is coupled to the segment therebelow using a coupling member of the type shown in  FIG. 7 ; in addition, it is also acceptable, after stacking a segment, to couple that segment to an assembled segment in the circumferential direction via a coupling means, such as a bolt and nut, as shown in  FIG. 5 . Such coupling of the segments in the circumferential direction and/or the vertical direction using the coupling member as shown in  FIG. 5  and  FIG.7  does not need to be performed for all the segments, and it may depend on the degree of damage of the inner wall surface of the manhole, or how it is damaged. Thus, by coupling assembled segments according to the state of the inner wall surface of the manhole in the circumferential direction and/or the vertical direction using coupling means as shown in  FIG. 5  and  FIG. 7 , it is possible to increase the strength of the portion of the rehabilitating pipe corresponding to the inner wall surface of the manhole where the degree of damage is high. 
   The rehabilitating pipe thus assembled inside the manhole is illustrated in  FIG. 9 ,  FIG. 10  and  FIG. 11 . In these figures, the pipe unit shown in  FIG. 6  is assembled in a state rotated by 90° about the pipe axis with respect to the underlying pipe unit, i.e., in a state wherein the end surfaces of all of the end plates are offset, but assembly can also be performed so that the end surfaces of all of the end plates of all of the segments are aligned. In that case, the same segments are stacked on the segments  1  ( 2 ) so that the surfaces of all the end plates align. 
   When the rehabilitating pipe is laid to the prescribed height, the upper part is covered with a cover sheet  22 . This cover sheet  22  comprises, for example, a thermosetting reinforced plastic made of reinforced fibers impregnated with a thermosetting resin and a setting agent, and is constituted so that it is inserted via a gap above the interior of the laid rehabilitating pipe  3 . For example, strip-shaped long cover sheets are lined up successively above the rehabilitating pipe, hardened, and joined mutually as well as to the rehabilitating pipe, thereby covering the entire upper part of the rehabilitating pipe. In that case, a hole  22   a  equivalent to the portion corresponding to the hole  4  is formed beforehand. 
   Thus, after completing the covering of the upper part of the rehabilitating pipe  3 , a well-known method is used to fill the gap between the manhole  5  and the rehabilitating pipe (all of the segments) with a filler like grout, and harden the filler material to integrate the rehabilitating pipe with the manhole  5  as a compound pipe.