Abstract:
In a method for repairing a drainage pipe, a resin pipe can be placed in an existing drainage pipe connected between connection bodies such as manholes while being buried in the ground, without causing an elongation. The method involves supplying a corrugated resin pipe  5 , which is made by forming, spirally or in a ring shape, ridge portions  5   c  of a hard resin on the outer wall of a soft resin pipe  5   d,    5   e  in which a reinforcement material  5   f  that restricts an elongation in the pipe axis direction has been embedded, into the existing drainage pipe through the upper opening of either of the connection bodies; inserting the head of the corrugated resin pipe  5  thus supplied from a drainage pipe opening connected to either of the connection bodies; pulling the corrugated resin pipe  5  thus inserted into the drainage pipe from the other side of the connection body; and laying the corrugated resin pipe  5  over the entire length of the drainage pipe.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates to a method for repairing drainage pipes such as an obsolete sewer pipe. 
   2. Background Art 
   If a sewer pipe buried in the ground for a long time becomes obsolete to cause its load resistance or waterproofness to be degraded, then there will exist a problem in that a road may sink or a flow-down ability of the pipe may become insufficient. 
   As a method to solve such a problem, there has been proposed and performed a drainage pipe repairing method in which a resin pipe is placed in an obsolete sewer pipe by utilizing the sewer pipe as a supporting body to produce a new sewer pipe. 
   Among the various existing methods of repairing the above-mentioned drainage pipe, for example, there is a pipe manufacturing method in which a band-shaped rigid PVC material is supplied in a manhole, and then inserted into an existing pipe while being formed into a pipe shape at the inlet portion of the existing pipe by a pipe manufacturing machine. 
   Further, there is also known a so-called sheath pipe technique in which instead of the band-shaped rigid PVC material, a short pipe that is shorter in length and smaller in pipe diameter than those of the existing pipe is carried in from a manhole, and then inserted into the existing pipe while being successively connected. 
   However, the above-mentioned pipe manufacturing technique requires a work facility dedicated for the pipe manufacturing machine and the like, and also skilled workers to perform the technique. On the other hand, the above-mentioned sheath pipe technique requires no pipe manufacturing machine, but the sheath pipe has been manufactured as a pipe, so that the pipe is not easily handled within a narrow manhole. 
   Moreover, both the techniques require a connecting operation to form a pipe shell within an existing pipe, so that there also exists a problem in that substantial working time must be spent to improve the sealing of the connection portions. 
   Therefore, for example, Japanese Patent Application Laid-Open No. 2002-38581 discloses a method as a recent technique capable of simply forming a pipe shell within an existing pipe without requiring a dedicated work facility. In this technique, as shown in  FIG. 9 , a flexible resin pipe  50  is supplied from a rotating drum  51 , inserted through a manhole  52  from one side of an existing pipe  53  by utilizing the flexibility of the resin pipe  50 , and then taken up from the other side of the existing pipe  53  by means of a winch  54 . 
   Further, in the figure, reference numeral  55  designates a cap mounted onto a head of the resin pipe  50 , and reference numeral  56  designates a wire connected to the cap  55 . 
   However, although the technique described in the above-mentioned Patent Publication uses the resin pipe  50  that is integrally made by forming, spirally or in a ring shape, corrugated portions having convex portions and concave portions (the convex portions are independent from each other) in the pipe axis direction thereof, or the resin pipe  50  that is integrally formed by making the surface thereof flat without convex portions and concave portions, priority is given to the flexibility over the tensile strength by taking the workability into account, so that there exists a problem in that when the resin pipe  50  is pulled roughly by the winch  54 , an elongation of the pipe that exceeds the original length of the resin pipe may occur and cause the load resistance to be degraded. 
   Also, when an attempt is made to construct the resin pipe  50  inserted into a lengthy existing pipe as seamless pipe, there exists another problem in that the resin pipe  50  also becomes lengthy and thus the rotating drum  51  for winding up the lengthy resin pipe  50  becomes larger in size. 
   The present invention is made to consider problems in a conventional drainage pipe repairing method as described above; a first object of the invention is to provide a drainage pipe repairing method in which a resin pipe can be pulled in an existing drainage pipe without developing an elongation, and a second object thereof is to provide a drainage pipe repairing method in which a resin pipe inserted into an existing pipe can achieve a compact design. 
   SUMMARY OF THE INVENTION 
   The present invention for achieving the above-mentioned objects is a method for repairing a drainage pipe which is connected between connection bodies such as manholes while being buried in the ground, and guides sewage, rainwater and the like to the connection bodies, comprising steps of: carrying in a corrugated resin pipe, which is made by forming, spirally or in a ring shape, ridge portions of a hard resin on the outer wall of a soft resin pipe in which a reinforcement material that restricts an elongation in the pipe axis direction has been embedded, from the upper opening of either of the connection bodies; inserting the head of the corrugated resin pipe thus carried in from a drainage pipe opening connected to either of the connection bodies; pulling the corrugated resin pipe thus inserted into the drainage pipe from the other side of the connection body; and laying the corrugated resin pipe over the entire length of the drainage pipe. 
   According to the present invention, a reinforcement material that restricts an elongation in the pipe axis direction has been embedded in a soft resin pipe comprising a corrugated resin pipe and improved the tensile strength, so that when the corrugated resin pipe is pulled in an existing drainage pipe, can be arranged without developing an elongation therein. 
   In the present invention, the above-mentioned soft resin pipe has a lower wound soft resin layer and an upper wound soft resin layer, and a reticulated reinforcement material as the reinforcement material can be placed between these resin layers. 
   The above-mentioned reticulated reinforcement material can be formed by being knitted into reticulated shape when a plurality of resin fibers is wound onto the lower wound soft resin layer. The reinforcement material can also be formed by winding spirally a resin reticulated band formed into a band shape having a mesh on the lower wound soft resin layer. 
   In the present invention, in a case where the above-mentioned corrugated resin pipe is composed so that it can be contracted in the pipe axis direction thereof, the corrugated resin pipe is arranged above a connection body while being contracted, and when the corrugated resin pipe is carried in the connection body, or when the pipe is carried in the connection body while being contracted and then inserted through a drainage pipe opening, the corrugated resin pipe can be extended successively from the head thereof. 
   In the present invention, the corrugated resin pipe can be contracted by being formed so as to provide a sag in the soft resin pipe and in the reticulated reinforcement material between the above-mentioned ridge portions. 
   In the present invention, when the corrugated resin pipe is laid over the entire length of the above-mentioned drainage pipe, and then a filler is injected between the inner wall of the drainage pipe and the outer wall of the corrugated resin pipe, the drainage pipe and the corrugated resin pipe can be integrated due to the hardening of the filler. In this case, when the outer peripheral side of the above-mentioned ridge portion is formed more widely than the base side thereof, the filler can be hardened while being placed around the base side, thereby providing an anchor effect on the ridge portion. 
   According to the present invention, when a new corrugated resin pipe is pulled into an obsolete existing pipe, no elongation develops in the corrugated resin pipe, so that the corrugated resin pipe can be arranged without degrading the load resistance thereof. 
   Further, using a corrugated resin pipe capable of being contracted in the pipe axis direction, allows the corrugated resin pipe inserted into an existing pipe to become compact, whereby an advantage is obtained in that the handling in transferring and executing becomes easy. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross sectional view showing a sewer pipe construction to which the present invention is applied. 
       FIG. 2  is a cross sectional view illustrating a drainage pipe repairing method in connection with a first embodiment of the present invention. 
       FIG. 3  is an enlarged view of the corrugated resin pipe shown in  FIG. 2 . 
       FIG. 4  ( a ) is an enlarged view of a ridge portion of the corrugated resin pipe shown in  FIG. 3 ;  FIG. 4  ( b ) and  FIG. 4  ( c ) are explanatory views showing variations of the ridge portion. 
       FIG. 5  is a cross sectional view showing a construction completion state according to the first embodiment. 
       FIGS. 6(   a ) and ( b ) show a corrugated resin pipe used in a second embodiment of the present invention.  FIG. 6  ( a ) is a side view showing a contracted state, and  FIG. 6  ( b ) is a side view showing an extended state. 
       FIG. 7  is an enlarged view of the corrugated resin pipe shown in  FIGS. 6(   a ) and ( b ). 
       FIG. 8  ( a ) is an explanatory view showing a state before the corrugated resin pipe according to the second embodiment is supplied into a drainage pipe, and  FIG. 8  ( b ) is an explanatory views showing a state in which the corrugated resin pipe is pulled into the drainage pipe. 
       FIG. 9  is a cross sectional view showing a conventional drainage pipe repairing method. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Hereinafter, the present invention will be explained based on the embodiments shown in the drawings. 
     FIG. 1  shows a drainage pipe construction to which the drainage pipe repairing method of the present invention is applied. 
   In  FIG. 1 , a plurality of drainage pipes  1  buried in the ground is normally composed of concrete pipes, and each drainage pipe  1  is connected to both openings  2   a  and  3   a  provided under respective manholes (connection bodies)  2  and  3  disposed in a drainage route. 
   When checking the drainage pipe  1 , first, a camera is inserted within the pipe to examine whether a crack exists or not. As a result of the examination, if a crack exists and a repairing is required, then as a preparatory repairing, the inside of the drainage pipe  1  is washed with a high-pressure washing water. Reference numeral  4  designates a water stop plug for preventing the washing water from entering into another drainage pipe. 
   Then, the drainage pipe repairing method of the present invention is applied to the washed drainage pipe. 
     FIG. 2  shows the first embodiment in connection with the drainage pipe repairing method. 
   In a drainage pipe construction in which one end of the drainage pipe  1  is connected to the left side manhole  2 , while the other end is connected to the right side manhole  3 , a rotating drum  6  onto which a corrugated resin pipe  5  has been wound is arranged at one of the manholes, near the upper opening  2   b  of the left side manhole  2  in this embodiment. 
   The corrugated resin pipe  5  released from the rotating drum  6  is inserted through the upper opening  2   b  into the left-side manhole  2 , and the head  5   a  thereof is mounted with a lead-in jig  7 . 
   On the other hand, arranged near an upper opening  3   b  of the right-side manhole  3  is a winch  8 , and a wire  9  released from the winch  8  is connected with the above-mentioned lead-in jig  7 . Therefore, driving the winch  8  in the wind-up direction causes the corrugated resin pipe  5  to be pulled by the wire  9  in the arrow A direction. 
   Further, in the drawings, reference numerals  10  and  11  designate arch-shape guides for guiding the corrugated resin pipe  5  into the left-side manhole  2 , and provided on the lower portion of the arch-shape guides are respective guide rollers  10   a  and  11   a  for smoothly conveying the corrugated resin pipe  5 . 
   Moreover, reference numerals  12  and  13  designate arch-shape guides provided on the outlet side of the drainage pipe  1 , and respective guide rollers  12   a  and  13   a  are provided on the portion on which the corrugated resin pipe  5  slides. 
     FIG. 3  shows an enlarged view of the above-mentioned corrugated resin pipe  5 . 
   The corrugated resin pipe  5  has a straight-pipe portion  5   b  and a ridge portion  5   c  formed spirally on the outer wall of the straight-pipe portion  5   b , and the above-mentioned straight-pipe portion  5   b  consists of a lower wound soft resin layer  5   d , an upper wound soft resin layer  5   e , and a reticulated reinforcement material  5   f  provided between both the resin layers. 
   The lower and upper soft resin layers  5   d  and  5   e  can be formed of a thermoplastic resin having a higher chemical resistance, for example, polyvinyl chloride and polyolefin resin, or of a thermoplastic elastomer, for example, those based on olefin and on styrene, and when both the lower wound soft resin layer  5   d  and the upper wound soft resin layer  5   e  are formed into pipes, the reticulated reinforcement material  5   f  is sandwiched between the resin layers  5   d  and  5   e.    
   The reticulated reinforcement material  5   f  is designed to be formed into a reticulated shape when reinforcing yarns supplied from a plurality of bobbins on a yarn supply board (not shown) are wound onto the lower wound soft resin layer  5   d , and the reinforcing yarns of the reticulated reinforcement material  5   f  thus formed are connected from one end of the corrugated resin pipe  5  to the other end thereof, so that the reinforcing yarns are designed to counteract the tension in the pipe axis direction. 
   Further, although the above-mentioned reinforcing yarns can use resin fibers such as those of polyester, nylon and polyamide, the yarns are not limited to them, and can also use yarns, for example, those of carbon fibers and the like. 
   Moreover, the ridge portion  5   c  can be composed of a thermoplastic resin having a higher chemical resistance, for example, polyvinyl chloride, polyolefin resin and the like. 
   Although the above-mentioned ridge portion  5   c , as shown in  FIG. 4  ( a ), can be formed into a trapezoid shape in the outward direction from the outer face of the straight pipe portion  5   b , when providing an anchor effect thereon, the ridge portion can be formed into a shape as shown in  FIG. 4  ( b ) or as shown in  FIG. 4  ( c ). 
   A ridge portion  5   g  shown in  FIG. 4  ( b ) is formed on a thin wall portion  5   h  on both the left and right sides of the base of the rectangular ridge portion  5   g.    
   With such a thin wall portion  5   h  provided, when the corrugated resin pipe  5  is pulled into the drainage pipe  1 , and then a grout (a mortar) is injected into an annular gap between the inner wall of the drainage pipe  1  and the outer wall of the corrugated resin pipe  5  thus pulled in, the grout becomes hardened while biting into the thin wall portion  5   h , so that the ridge portion  5   g  can have an anchor effect. 
   Moreover, a ridge portion  5   i  shown in  FIG. 4  ( c ) is formed so as to be tapered toward the pipe center side. Thus, providing inclined faces  5   j  exhibiting a taper on both the left and right sides of the ridge portion  5   i  allows also the ridge portion  5   i  to have an anchor effect. 
   Then, with reference again to  FIG. 2 , the drainage pipe repairing method will be explained. 
   The method comprises steps of: 
   releasing the corrugated resin pipe  5  wound onto the rotating drum  6 , and inserting the head  5   a  thereof into the manhole  2  through the top opening  2   b  of one manhole  2  of the manholes  2  and  3  adjacent to each other in the disposed route; 
   mounting the lead-in jig  7  an one end of the corrugated resin pipe  5  thus carried in, with the lead-in jig  7  in turn being connected to the wire  9  pulled from the other manhole  3 ; and 
   driving the winch  8  causes the wire  9  to be wound up, thereby pulling the corrugated resin pipe  5  into the drainage pipe  1 . 
   Further, although the corrugated resin pipe  5 , when pulled into the drainage pipe  1 , is pulled while coming in contact with the inner wall of the drainage pipe  1 , the outer diameter of the corrugated resin pipe  5  is selected so as to be smaller than the inside diameter of the drainage pipe  1 , so that the sliding resistance when pulled is small. 
   Moreover, although when the corrugated resin pipe  5  is pulled by the wire  9 , a tensile load is concentrated onto the straight pipe portion  5   b  (see  FIG. 3 ) of soft resin layers, the straight pipe portion  5   b  is provided with the reticulated reinforcement material  5   f  to counteract the tensile load, so that the corrugated resin pipe  5  does not elongate to a length more than that specified in the product specification (i.e. does not elongate beyond a product length). 
   When the corrugated resin pipe  5  is penetrated into the drainage pipe  1 , as shown in  FIG. 5 , a grout  14  is injected in an annular gap S between the inner wall of the drainage pipe  1  and the outer wall of the corrugated resin pipe  5 . 
   The grout  14  is produced by mixing a mortar and a chemical, and filled into the annular gap S in order to provide water stoppage and integration. 
   If the ridge portion  5   c  of the corrugated resin pipe  5  has an anchor effect as shown in  FIG. 4  ( b ) or  FIG. 4  ( c ), then when the hardening of the grout  14  thus filled has completed, the corrugated resin pipe  5  is integrated through the grout  14  with the drainage pipe  1 , thereby preventing the resin pipe from being separated from the grout  14 . 
   Further, a filler for integrating the corrugated resin pipe  5  with the drainage pipe  1  is not limited to the above-mentioned grout  14 , and may be a plastic foam, for example, a polyurethane foam obtained by mixing a base material having isocyanate as a major ingredient with a hardening agent having polyol as a major ingredient. 
     FIGS. 6(   a ) and ( b ) and  FIG. 7  show a second embodiment of the drainage pipe repairing method of the present invention. 
   First,  FIGS. 6(   a ) and ( b ) show the composition of a corrugated resin pipe  20  used in the second embodiment, in which the corrugated resin pipe  20  is designed to be deformed into a contracted state shown in  FIG. 6  ( a ) by being compressed in the pipe axis direction, and deformed into an extended state shown in  FIG. 6  ( b ) by being pulled in the pipe axis direction, whereby the resin pipe when contracted can be shrunk into a length of about one third the pipe length L when extended. 
   This expansible corrugated resin pipe  20 , as shown in the enlarged view of  FIG. 7 , consists of a straight-pipe portion  20   a  and a ridge portion  20   b  formed spirally on the outer face of the straight-pipe portion  20   a.    
   The straight-pipe portion  20   a  consists of a lower wound soft resin layer  20   c , an upper wound soft resin layer  20   d , and a reticulated reinforcement material  20   e  provided between both the resin layers. 
   The straight-pipe portion  20   a  is formed into a state in which the portion  20   a  is curved somewhat toward the pipe center between the ridge portions  20   b  adjacent thereto. Providing a deflection forcedly in this manner allows the corrugated resin pipe  20   a  to be compressed in the pipe axis direction and shrunk into a bellows shape. 
   The lower and upper soft resin layers  20   c  and  20   d  can be formed of a thermoplastic resin having a higher chemical resistance, for example, polyvinyl chloride and polyolefin resin, or of a thermoplastic elastomer, for example, those based on olefin and on styrene. 
   The reticulated reinforcement material  20   e  is obtained by forming a resin such as polyester, nylon and polyamide into a band shape having a mesh, and formed by winding spirally a reticulated band of a width W onto the outer face of the lower wound soft resin layer  20   c  in a process in which the lower wound soft resin layer  20   c  is formed into a pipe. 
   The reticulated reinforcement material  20   e  has a flexibility such that the material can be deformed following up a condition in which the straight-pipe portion  20   a  is folded into a bellows shape when the corrugated resin pipe  20  is contracted, so that the material has also a predetermined tensile strength such that the straight-pipe portion  5   a  does not extend so as to exceed a condition in which the portion is pulled in a straight line when pulled in the pipe axis direction. 
   Moreover, the ridge portion  20   b  can be formed of a thermoplastic resin having a higher chemical resistance, for example, polyvinyl chloride and polyolefin resin, and can be formed into a shape shown in  FIG. 4  ( b ) or  FIG. 4  ( c ) in order to enhance an anchor effect. 
   Then, the drainage pipe repairing method by using the above-mentioned expansible corrugated resin pipe  20  will be explained with reference to  FIGS. 8(   a ) and ( b ). Further, in the figure, the same constituents as  FIG. 2  are designated by the same reference numerals to omit their explanations. 
     FIG. 8  ( a ) shows a state in which the corrugated resin pipe  20  made compact by being contracted in the pipe axis direction is loaded on the deck of a truck  21 , and is forcedly introduced through the manhole  2 .  FIG. 8  ( b ) shows a state in which the truck  21  is stopped near the manhole  2 , and the corrugated resin pipe  20  loaded on the deck is sequentially extended from the head and inserted into the manhole  2 . 
   The corrugated resin pipe  20  to be extended is lowered downward from the position of the guide roller  11   a , faced in the horizontal direction at the position of the guide roller  22  provided near the opening  2   a  under the manhole  2 , and then introduced into the drainage pipe  1 . 
   The corrugated resin pipe  20  thus introduced into the drainage pipe  1  is pulled in the direction of the arrow A by the wire  9 , and then pulled out through the manhole  3  on the other side. 
   Further, the position at which the corrugated resin pipe  20  starts to extend may be on the deck of the truck  21 , or may be in the opening  2   a  of the manhole  2 . 
   In this way, in the drainage pipe repairing method using the expansible corrugated resin pipe  20 , the corrugated resin pipe  20  before being carried in the manhole  2  can be made compact, so that the corrugated resin pipe  20  is very easily handled without being bulky when transported. In addition, a large rotating drum is not required to be installed, so that a large-diameter corrugated resin pipe  20  without being limited by the bore size can be used to repair the drainage pipe  1 . 
   Further, in the above-mentioned first embodiment, the reticulated reinforcement material  5   f  used for the corrugated resin pipe  5  can be used for the corrugated resin pipe  20  of the second embodiment, and conversely, the reticulated reinforcement material  20   e  used for the corrugated resin pipe  20  can be used as a reinforcement material of the corrugated resin pipe  5  in connection with the first embodiment. 
   Moreover, although the ridge portions of the above-mentioned embodiments are spirally formed, the ridge portions are not limited to the shape, and can be formed into a ring shape. 
   INDUSTRIAL APPLICABILITY 
   The present invention relates to a method for repairing a drainage pipe applicable to the repairing of sewer pipes and the like, and is suitable for a sewer pipe that becomes obsolete to cause the load resistance and water stoppage ability to be degraded, and for the installation of a new drainage pipe performed inside the sewer pipe used as a supporting body.