Abstract:
A segment is coupled to another segment in the circumferential and longitudinal directions to assemble a rehabilitating pipe for rehabilitating an existing pipe. The segment is provided with a recessed part in a coupling surface in the longitudinal direction at a portion that is brought into contact with the bottom surface of the existing pipe when the rehabilitating pipe is laid inside the existing pipe. When the segments are coupled in the longitudinal direction of the rehabilitating pipe, the recessed part forms a gap between the coupling surfaces to provide a space for accommodating waste existing on the bottom surface of the existing pipe, thus enabling the coupling work in the longitudinal direction to be performed simply and in a short period of time because it is unnecessary to remove the waste.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a segment adapted for use for a rehabilitating pipe that is assembled to rehabilitate an existing pipe, such as a sewer pipe.  
         [0003]     2. Description of the Prior Art  
         [0004]     A method of rehabilitating an existing pipe is known from Japanese Patent Laid Open Publication No. 2003-286742 and the like, wherein a compound pipe is constructed to rehabilitate an existing pipe, such as a sewer pipe, as shown in  FIG. 5 , by assembling and laying inside an existing pipe  4  a rehabilitating pipe  3  whose outer diameter is slightly less than the inner diameter of the existing pipe, and then filling and hardening a filler in the gap between the outer circumference of the rehabilitating pipe  3  and the inner wall surface of the existing pipe  4 . If the rehabilitating pipe  3  is a circular pipe whose diameter is approximately 1,000-1,800 mm, the rehabilitating pipe  3  is assembled by forming short rings by coupling a plurality of segments  1  in the circumferential direction of the rehabilitating pipe  3 , and then successively and mutually coupling the rings in the longitudinal direction of the rehabilitating pipe  3  (ring assembly). Since ring assembly is problematic for the case wherein the rehabilitating pipe  3  has a large diameter of approximately 2,000 mm or greater or is a rectangular pipe, the rehabilitating pipe  3  is assembled by successively coupling the segments  1  in units, one by one, in the circumferential direction and the longitudinal direction of the rehabilitating pipe  3  (unit assembly).  
         [0005]     In the construction work of laying the rehabilitating pipe, it is common to position the rehabilitating pipe so that the outer circumference of a lower end part thereof contacts the bottom of the existing pipe. Consequently, particularly in the case of ring assembly, a segment  1 ′ is moved, as shown in  FIG. 7 , so that the outer circumference of the lower end part thereof rubs against the pipe bottom  4   a  of the existing pipe when it is coupled in the longitudinal direction to a segment  1  that is already coupled to the rehabilitating pipe and lies in contact with a pipe bottom  4   a.    
         [0006]     The segments  1  and  1 ′ are usually provided with side plates  102  and  103  on both sides in the longitudinal direction, whose outer surface forms a coupling surface and whose outer entire surface is formed planarly. Consequently, as shown in  FIG. 7 , it is often the case that waste, sand, and the like get caught on the pipe bottom  4   a  of the existing pipe between the outer surfaces of the mutual side plates  102  and  103  of the segments  1  and  1 ′, thereby creating a gap and making it impossible to mutually tightly seal the outer surfaces of the side plates  102  and  103 . In such a case, the waste that has gotten caught must be eliminated, which is unfortunately time consuming, and increases the time it takes to perform the coupling work. This problem is remarkable particularly in the case of ring assembly. In addition, if coupling is performed as is without eliminating the waste that has gotten caught, then the above mentioned outer surfaces will not be mutually tightly sealed, creating the problem wherein the watertightness in the coupling portion in the longitudinal direction can no longer be ensured.  
         [0007]     It is therefore an object of the present invention to provide a segment for a rehabilitating pipe enabling the coupling work in the longitudinal direction to be performed more simply and in a shorter period of time and enabling the watertightness of the coupling portion in the longitudinal direction to be improved.  
       SUMMARY OF THE INVENTION  
       [0008]     A segment for a rehabilitating pipe according to the invention is coupled to another segment in the circumferential and longitudinal directions to assemble the rehabilitating pipe for rehabilitating an existing pipe. The segment is provided with a recessed part in a coupling surface in the longitudinal direction to form a gap between the coupling surfaces when the segments are coupled in the longitudinal direction of the rehabilitating pipe. The recessed part is formed at that portion of the segment that is brought into contact with the bottom surface of the existing pipe when the rehabilitating pipe is laid inside the existing pipe.  
         [0009]     The recessed part is formed such that the coupling surface is made flexible at the recessed part, and preferably extends in the coupling surface across the entire length of the circumferential direction of the segment. Such a recessed part is preferably formed at both coupling surfaces of the segment in the longitudinal direction of the rehabilitating pipe.  
         [0010]     According to the invention, the recessed parts in the coupling surfaces form a gap when the segments are coupled in the longitudinal direction. Therefore, even if waste and the like exists on the bottom of the existing pipe and is caught between the coupling surfaces of the segments, the mutual coupling surfaces can be tightly sealed to one another and the segments can thereby be mutually coupled in the longitudinal direction without eliminating that waste and the like as long as the gap has a space to accommodate the waste. Such an arrangement enables the coupling work in the longitudinal direction to be performed more simply and in a shorter time than conventionally and also improves the watertightness of the coupling portions of the segments in the longitudinal direction.  
         [0011]     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  
       [0012]      FIG. 1  is a partially broken perspective view showing a segment according to the present invention.  
         [0013]      FIG. 2  is a perspective view showing how the segments are coupled in the circumferential direction and in the longitudinal direction.  
         [0014]      FIG. 3  is a longitudinal cross sectional view showing a state wherein the segments are mutually coupled in the circumferential direction.  
         [0015]      FIG. 4  is a radial cross sectional view showing a state wherein the segments are mutually coupled in the longitudinal direction.  
         [0016]      FIG. 5  is a partially broken perspective view showing a state wherein the segments are coupled to assemble a rehabilitating pipe inside the existing pipe.  
         [0017]      FIG. 6  is an explanatory view showing how waste is caught on the bottom of the existing pipe when the segments are coupled in the longitudinal direction in the invention.  
         [0018]      FIG. 7  is an explanatory diagram showing how waste is caught on the bottom of the existing pipe when the segments are coupled in the longitudinal direction in the conventional method. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     The invention will be described based on the preferred embodiments, referring to the attached drawings.  
         [0020]     A segment  1  is used to assemble a rehabilitating pipe to rehabilitate an existing pipe, and formed as a unitary block. As shown in  FIG. 1 , the segment  1  comprises an inner plate  101 , side plates  102  and  103 , end plates  104  and  105 , and respectively two each of reinforcing plates  106  and  107 . These plates  101  through  107  are integrally molded to provide a plastic segment using 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.  
         [0021]     The inner plate  101  is formed as a plate having a prescribed width and is arcuately curved at a prescribed angle that divides the circumference into a plurality of equal parts, e.g., 72° (five parts). The bottom surface of the inner plate  101  corresponds to the inner circumferential surface of the rehabilitating pipe with the circumferential direction of the arc corresponding to the circumferential direction of the rehabilitating pipe and the latitudinal direction of the arc to the longitudinal direction thereof. A plurality of rectangular openings  101   a  is formed respectively on both end parts of the inner plate  101  for performing from the inside the work to mutually couple the segments  1  in the circumferential direction.  
         [0022]     The side plates  102  and  103  are formed at both side edges across the entire length along the circumferential direction of the inner plate  101 , and are provided upright outwardly at a prescribed height on the top surface of the inner plate  101 . A plurality of through holes  102   a  and  103   a  (herein, 14) is formed in each of the side plates  102  and  103  at a prescribed interval in the circumferential direction for passing therethrough coupling members in the longitudinal direction, as discussed later. In addition, although not shown in  FIG. 1 , a protruding part (protruding line)  102   c  and a recessed part (recessed line)  103   c , having shapes that substantially conform to one another, are formed at the lower end part of the outer surface of the respective side plates  102  and  103  across the entire lengths thereof, as shown in  FIG. 4 .  
         [0023]     In addition, as shown in  FIG. 4  and  FIG. 6 , in the outer surfaces of the respective side plates  102  and  103  at the outer end parts in the radial direction of the rehabilitating pipe (the upper end part in  FIG. 4 , and the lower end part in  FIG. 6 ), recessed parts  102   d  and  103   d  are formed extending across the entire length of the side plates  102  and  103  along the circumferential direction of the segment  1 . The depth of the recessed parts  102   d  and  103   d  in the lateral direction in  FIG. 4  and  FIG. 6  is preferably approximately half the thickness of the side plates  102  and  103 , e.g., a depth of approximately 3 mm for a side plate of a thickness of approximately 6 mm; and the dimension in the vertical direction in  FIG. 4  and  FIG. 6  is preferably, for example, approximately 10 mm or greater. However, it will be understood that the present invention is not particularly limited to these dimensions.  
         [0024]     The end plates  104  and  105  are formed at both end edges of the inner plate  101  across the entire length along the longitudinal direction thereof, and are provided upright outwardly on the top surface of the inner plate  101  at a height the same as each of the side plates. Through holes  104   a  and  105   a  are formed at a plurality of locations in the end plates  104  and  105  for passing therethrough bolts that mutually couple the segments  1  in the circumferential direction (refer also to  FIG. 3 ). In addition, although not shown in  FIG. 1 , recessed parts  104   b  and  104   c  and protruding parts  105   b  and  105   c , having shapes that substantially conform to one another, are formed at the middle part and the lower end part of the outer surfaces of the respective end plates  104  and  105  across the entire length thereof, as shown in  FIG. 3 .  
         [0025]     The reinforcing plates  106  and  107  reinforce the mechanical strength of the entire segment  1 , and are provided upright at a prescribed height outwardly on the inner plate  101  on the inner sides of the side plates  102  and  103 . In the reinforcing plates  106  and  107  are formed a plurality of through holes  106   a  and notched parts  107   a  for inserting therethrough the coupling members in the longitudinal direction at a position corresponding respectively to the through holes  102   a  and  103   a  of the side plates  102  and  103 .  
         [0026]     In addition, laterally projecting, small, right triangular protruding plates  103   b ,  106   b  and  107   b  (the protruding plates of the side plate  102  are not shown) are formed at a plurality of locations on the inside surfaces of the side plates  102  and  103  and both side surfaces of the reinforcing plates  106  and  107  to prevent deformation respectively thereof, thereby forming a rib structure that enhances the strength of the segment  1 .  
         [0027]     When the existing pipe to be repaired is circular in cross sectional shape, the segment  1  corresponds to one block obtained when a circular pipe with outer and inner circumference curvatures respectively adapted to that of the existing pipe is cut off in slices at a prescribed width and the thus sliced pipe is divided for segmentation in the circumferential direction into parts (preferably into equal parts).  
         [0028]     The number of reinforcing plates or the number of protruding plates can be varied in accordance with the required strength of the segment; if strong, then some or all can be omitted. In addition, the segment functions as a rehabilitating or repairing unit, so that it is not limited to an arcuate type or fan type as shown in  FIG. 1 , and can be made a parallelepiped in accordance with the cross sectional shape or size of the existing pipe or the repair location of the existing pipe, and can also be made a shape bent into a rounded right angle.  
         [0029]     The segments are successively coupled in the circumferential direction with the outer surfaces of every end plate of each segment mutually aligned and also the inner surfaces of every inner plate thereof mutually aligned. The segments are also successively coupled in the longitudinal direction so that the outer surfaces of every side plate of each segment are mutually aligned and the inner surfaces of each inner plate are mutually aligned. Such processes allow a rehabilitating pipe to be assembled with the inner entire surface thereof being uniform without any gap between the segments.  
         [0030]     The following explains the details of a method for laying a rehabilitating pipe inside an existing pipe using the segments.  
         [0031]     First, the segments  1  are carried inside the existing pipe, and successively coupled in the circumferential direction, as shown in  FIG. 2 . This coupling is performed, as shown in detail in  FIG. 3 , by interfitting the recessed parts  104   b  and  104   c  and the protruding parts  105   b  and  105   c  of all the segments  1  to position the inner surfaces of all the inner plates  101  so that they form the same surface and to position the outer surfaces of all the side plates  102  so that they form the same surface and the outer surfaces of all the side plates  103  so that they form the same surface; mutually, tightly sealing the outer surfaces of the end plates  104  and  105  of all the segments  1 ; inserting bolts  6  into the through holes  104   a  and  105   a  from the opening  101   a  of the inner plate  101 ; screwing on nuts  7 ; and tightening both end plates  104  and  105 . By coating the interfitted recessed parts  104   b  and  104   c  with a sealing material (not shown) prior to this coupling, the watertightness of the coupled part can be enhanced. When the coupling is completed, a cover (not shown) and the like tightly seals each opening  101   a . At this time, the inner surface of the cover is continuous with the inner surface of each inner plate, thus forming a uniform inner surface.  
         [0032]     After the segments are coupled so as to form a ring shape or after a prescribed number of segments are coupled in the circumferential direction C, another segment  1 ′ is coupled in the longitudinal direction L to the segment already coupled in the circumferential direction, as shown in  FIG. 2 .  
         [0033]     The coupling in the longitudinal direction is performed, as shown in  FIG. 4 , by using a rod shaped coupling member  11  made of metal and that integrally joins a rod  11   b  with one end thereof formed as a screw part  11   a , and the other end as a nut part  11   c . A screw hole  11   d  is formed in the nut part  11   c  to receive the screw part  11   a  of the rod of another coupling member.  
         [0034]     In  FIG. 4 , the coupling member  11  on the right side is already joined to the nut part  11   c  of another coupling member, shown by the chain line, and fixed to the segment  1 . To couple another segment  1 ′ to this segment  1 , both segments  1  and  1 ′ are first positioned so that the inner surfaces of the inner plates  101  thereof align and form a uniform surface. The outer surfaces of the side plates  102  and  103  of both the segments are then brought into tightly contact with each other with the nut part  11   c  protruding from the side plate  102  of the segment  1  interfitted with a through hole  103   a  of the side plate  103  of the segment  1 ′ and with the protruding part  102   c  of the segment  1  interfitted with the recessed part  103   c  of the segment member  1 ′. In this case, by coating the recessed part  103   c  with a sealing material (not shown) beforehand, watertightness can be enhanced.  
         [0035]     A coupling member  11 ′ is then inserted through from the through hole  102   a  of the side plate  102  of the 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 coupling member  11 . At this time, the screw part  11   a ′ and a rod  1   b ′ are inserted from the through hole  102   a  through the through hole  106   a , two notched parts  107   a , and the through hole  106   a , and screwed in.  
         [0036]     When the screw part  11   a ′ is screwed into the screw hole  11   d  until a nut part  11   c  of the coupling member  11 ′ hits against the reinforcing plate  106  of the segment  1 ′, the coupling member  11 ′ clamps the segment  1 ′ against the segment  1  to thereby couple both segments  1  and  1 ′. Because the coupling of every segment is performed using, for example, four coupling members per segment, both segments  1  and  1 ′ are coupled rigidly in the longitudinal direction.  
         [0037]     When the segment  1  in  FIG. 4  is the initial segment in the longitudinal direction, the coupling member as shown in  FIG. 4  cannot be used, and therefore a fixing member having a structure the same as the nut part  11   c  that can fix the segment  1  is used as the coupling member.  
         [0038]     During assembly in the longitudinal direction, as shown in  FIG. 6 , the segment  1 ′ to be coupled is moved toward the segments that are coupled as a ring and lie in contact with the pipe bottom  4   a  of the existing pipe, so that the outer circumference of its lower end part of the segment  1 ′ rubs against the pipe bottom  4   a  of the existing pipe. In this situation, if waste  20  is present on the pipe bottom  4   a , then the waste is pressed to the side plate  103  of the segment  1 ′, and is caught between the outer surfaces of the lower end parts of the side plates  102  and  103  of the segments  1  and  1 ′.  
         [0039]     However, the side plates  102  and  103  are provided with the recessed parts  102   d  and  103   d  at the lower end parts of the outer surfaces thereof, so that a gap is formed between the side plates  102  and  103  when both the segments  1  and  1 ′ are mutually coupled in the longitudinal direction. The gap thus formed can accommodate the waste  20 , even if the waste is not removed, as long as it is not a large amount, or its particles are not large, as shown on an enlarged scale in  FIG. 6 .  
         [0040]     Furthermore, the recessed parts  102   d  and  103   d  make the lower end parts of the side plates  102  and  103  thin walled, so that they are elastically deformable in the longitudinal direction. Consequently, if the amount of waste  20  that is caught is large, or if the particles of the waste  20  are large, then this can be handled to some extent because the lower end parts of the side plates  102  and  103  are pressed by the waste  20 , and elastically deform in one direction of the longitudinal direction and the reverse direction thereof so that they become mutually spaced apart, as shown by the arrow in the enlarged view on the lower side of  FIG. 6 , thereby enlarging the space of the gap that can accommodate the waste. Thus, even if waste is caught to some extent, the outer surfaces of the side plates  102  and  103  can be mutually tightly sealed, and the segments  1  and  1 ′ can be mutually coupled in the longitudinal direction.  
         [0041]     As described above, the rehabilitating pipe  3  can be assemble and laid, as shown in  FIG. 5 , by successively and mutually coupling segments  1  in the circumferential direction and the longitudinal direction inside the existing pipe  4 . After completion of the pipe laying, the gap between the existing pipe  4  and each of the segments  1  of the rehabilitating pipe  3  is filled with grout (not shown), which is hardened to integrate with the existing pipe  4  as a compound pipe. The coupled segments  1  are schematically depicted in  FIG. 5  as a simple block shape, and only one reinforcing plate is shown for the segments  1 . In  FIG. 5  the coupling members  11  are also illustrated with some of them depicted by dashed lines. Furthermore, although all of the segments  1  in  FIG. 5  are coupled with their end plates aligned in the longitudinal direction, they can also be coupled with their end plate positions offset. In addition, it is understood that the number of coupling members  11  inserted per segment  1  is not limited to four.  
         [0042]     In the above embodiment, the segments are successively coupled at only one side of the existing pipe in the longitudinal direction (single sided coupling), but it is also possible to successively couple the segments at both sides in the longitudinal direction (bilateral coupling). In this case, the pipe laying time can be reduced because the segments can be coupled from both sides.  
         [0043]     Furthermore, in the embodiment explained above, the segments are used for a circular rehabilitating pipe assembly; however, a segment according to the invention can also be used for assembly of a rehabilitating pipe whose cross-sectional shape is, e.g., a rectangular shape, a U shape, a semicircular shape, and the like.