Piping structure and method for rehabilitating pipe conduit in existing piping

Abstract

To provide a piping structure in which rehabilitation is performed for existing piping that is difficult to replace by excavation due to its on-site installation state, and a method for rehabilitating existing piping.SOLUTION: A piping structure according to the present invention is a piping structure in which existing piping is rehabilitated, and which is housed inside the existing piping and comprises a rehabilitation pipe conduit in which a plurality of resin pipes is joined together via a fusion part, where an SDR value, which is a ratio of an outer diameter D to a wall thickness T of the resin pipes, is 13.5 or less. An ellipticity of the resin pipes is preferably 5 mm or less, and a deflection rate of the resin pipes is preferably 5% or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a piping structure and a method for rehabilitating an existing piping. [Background technology]

[0002] When updating existing pipes such as water pipes or gas pipes buried underground, it may not be possible to replace the existing pipes because excavation work cannot be carried out in the surrounding area due to the surrounding road conditions or the circumstances of the installation location. In such cases, a technology is known in which a deformable polyethylene resin pipe or the like is inserted inside the existing pipe while leaving it in place to rehabilitate it. The following Patent Document 1 discloses a method for lining the inside of an existing pipe by inserting a polyethylene resin pipe into the inside of the existing pipe, applying pressure to the inside of the resin pipe while heating it to the softening temperature of polyethylene or higher after insertion, and expanding the diameter of the polyethylene resin pipe. According to the technology described in Patent Document 1, it is described that a polyethylene resin film having a thickness that fits along the inner wall of the existing pipe can be formed, thereby forming an inside pipe lining. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-170367 Summary of the Invention [Problem to be solved by the invention]

[0004] As mentioned above, when it is not possible to replace the existing piping, the existing piping is left in place and a thin plastic pipe with a small diameter is inserted into the existing piping to create an internal lining, which is then carried out on-site. For example, a polyethylene pipe material, the cross-sectional shape of which has been reduced in diameter in advance to a circular or heart shape, is inserted while being heated to a temperature above its softening point and below its melting point, and then pressure is applied from the inside to expand the diameter and form it into a tubular shape that fits along the existing piping, creating a rehabilitated pipeline. However, what has been done so far has mainly been with thin-walled piping such as sewer pipes, which have relatively low internal pressure, and there has been a problem in that it is not easy to rehabilitate existing piping that is subject to internal pressure, such as gas pipes and drinking water pipes, while leaving the existing piping in place.

[0005] In view of the above-mentioned circumstances, the present invention aims to provide a piping structure and a method for rehabilitating an existing pipe that can be applied when a plastic pipe is inserted inside the existing pipe while leaving it in place to create a regenerated pipeline. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention proposes the following aspects. <1> A piping structure according to one embodiment of the present invention is a piping structure for rehabilitating an existing piping, which is housed inside the existing piping and includes a rehabilitating pipeline formed by joining a plurality of plastic pipes together via fusion joints, and is characterized in that an SDR value, which is a ratio of an outer diameter D to a wall thickness T of the plastic pipes, is 13.5 or less.

[0007] A new pipeline can be formed inside an existing pipe by providing a rehabilitating pipeline made of plastic pipes joined together via fusion joints inside the existing pipe. If the SDR value, which is the ratio of the outer diameter D and wall thickness T of the plastic pipe, is 13.5 or less, it can be made into a self-supporting pipe with sufficient pipe thickness, and can be applied without any problems even if the existing pipe is a pipe that is subject to internal pressure, such as a drinking water pipe or gas pipe. Of course, it can also be applied without any problems to existing pipes that are not subject to large internal pressure, such as a sewer pipe.

[0008] <2> The above <1> In the piping structure according to the present invention, it is preferable that the ellipticity of the resin pipe is 5 mm or less.

[0009] Conventionally, when rehabilitating existing pipes, the polyethylene resin film used for the internal lining of the pipe is used in the rehabilitation structure, and the polyethylene resin film conforms to the inner surface of the existing pipe. Therefore, if the existing pipe is deformed into an ellipse, the rehabilitated pipe is likely to be deformed into an ellipse as well. In this case, the combined strength of the existing pipe and the constituent pipes is required to withstand earth pressure and internal pressure. In contrast, the ellipticity of the resin pipes that make up the rehabilitated pipeline is 5 mm or less, and combined with the SDR value of 13.5 or less, the rehabilitated pipeline alone can be strong enough to withstand earth pressure and water pressure.

[0010] <3> The above <1> In the piping structure according to the present invention, it is preferable that the resin pipe has a deflection rate of 5% or less.

[0011] Conventionally, when rehabilitating existing pipes, the polyethylene resin film used for the internal lining of the pipe is used in the rehabilitation structure, and the polyethylene resin film conforms to the inner surface of the existing pipe. Therefore, if the existing pipe is deformed into an ellipse, the rehabilitated pipe is likely to be deformed into an ellipse as well. In this case, the combined strength of the existing pipe and the constituent pipes is required to withstand earth pressure and internal pressure. In contrast, the deflection rate of the resin pipes that make up the rehabilitated pipeline is 5% or less, and combined with the SDR value of 13.5 or less, it is possible to create a piping structure with sufficient strength to withstand earth pressure and water pressure with just the rehabilitated pipeline.

[0012] <4> The above <1> In the piping structure according to the present invention, the resin pipe is preferably made of a polyolefin resin.

[0013] Resin pipes made of polyolefin resins including polyethylene are desirable as materials for constructing rehabilitated pipelines from the viewpoints of earthquake resistance, durability, and not adversely affecting water quality, etc. For example, when the existing piping is for drinking water, high-density polyethylene can be used.

[0014] <5> The above <1> In the piping structure according to the present invention, the fusion portion is preferably a butt fusion portion or a fusion portion formed by an electric fusion joint.

[0015] A butt fusion joint is a joint formed by heating plastic pipes to a softening temperature below the melting point and butting them together, while an electric fusion joint has a fusion joint formed by mutually fusing the contact parts of an electric fusion joint and a plastic pipe. The fusion joint may be a butt fusion joint or a fusion joint using an electric fusion joint. Butt fusion parts and fusion parts using electric fusion joints are widely used to join plastic pipes, and either type of fusion part is excellent for piping connections and can be suitably applied to any application, such as drinking water pipes, gas pipes, and sewer pipes.

[0016] <6> One embodiment of the present invention relates to a method for rehabilitating an existing piping, which rehabilitates an existing piping installed underground or under a structure, and is characterized in that it includes forming an outlet side vertical hole and an inlet side vertical hole at respective spaced positions along the existing piping, connecting the aboveground and the existing piping below, forming an inlet side work port in the existing piping so as to communicate with the inlet side vertical hole, forming an outlet side work port in the existing piping so as to communicate with the outlet side vertical hole, then inserting a plurality of plastic pipes of a predetermined length into the interior of the existing piping through the inlet side vertical hole and the inlet side work port, extending the plurality of plastic pipes inserted into the existing piping through fusion portions, and moving the pipes toward the outlet side work port to form a rehabilitated pipeline.

[0017] When rehabilitating existing pipes installed underground or under a structure, it may be difficult to excavate around the existing pipes depending on the conditions around them. In such cases, it is necessary to build a new rehabilitation pipeline while leaving the existing pipes in place. Therefore, multiple resin pipes that can be inserted into the existing piping are inserted from the inlet side work port, and multiple adjacent resin pipes are joined inside the existing piping by fusion while multiple resin pipes are inserted into the existing piping. By sequentially joining the resin pipes, a new rehabilitated pipeline is formed inside the existing piping, and the existing pipeline can be regenerated.

[0018] <7> The above <6> In the method for rehabilitating existing piping relating to the above, it is preferable to extend a plurality of the plastic pipes extending from within the existing piping below the inlet side vertical hole toward within the existing piping below the outlet side vertical hole, reach below the outlet side vertical hole, form an additional inlet side vertical hole along the existing piping starting from the inlet side vertical hole at a position a predetermined distance away from the side on the opposite side to the side on which the outlet side vertical hole was formed, form an additional inlet side work port in the existing piping below that which communicates with the additional inlet side vertical hole, insert a plurality of plastic pipes into the existing piping from the additional inlet side vertical hole and the additional inlet side work port, extend the required number of plastic pipes, extend the tips of the extended plastic pipes to reach below the inlet side vertical hole that was the starting point, and fuse the tips of the extended plastic pipes to the plastic pipe present below the inlet side vertical hole that was the starting point.

[0019] In the pipeline rehabilitation of existing piping, after the pipeline rehabilitation of the existing piping between the inlet side vertical hole and the outlet side vertical hole, it is sometimes necessary to continue and rehabilitate the existing piping in other positions continuing between the inlet side vertical hole and the outlet side vertical hole. In this case, an additional inlet side shaft and inlet side work opening are formed on the side of the existing piping that has not been rehabilitated, i.e., at a position away from the inlet side shaft that was the starting point previously. Then, multiple plastic pipes are introduced into the existing piping through these, and multiple plastic pipes are added through fusion sections. By fusing the tip side of the added plastic pipe to the plastic pipe existing on the inlet side work opening side that was the starting point previously, a new pipeline can be rehabilitated so that it continues to the area that was previously rehabilitated. By repeatedly forming additional inlet side vertical holes and inlet side work ports along the existing piping and repeatedly fusing multiple plastic pipes, it is possible to rehabilitate the entire length of the existing piping, even if it is long. Even if the installation conditions of the existing pipe make it impossible to perform excavation on site, if it is possible to form an inlet vertical hole and an inlet work port along the length of the existing pipe, the pipeline can be reliably rehabilitated over the entire length of the existing pipe.

[0020] <8> The above <6> or <7> In the method for restoring existing piping according to the above aspect, it is preferable that the SDR value, which is the ratio of the outer diameter D to the wall thickness T of the resin pipe, is 13.5 or less. <9> The above <6> or <7> In the method for restoring existing piping according to the above aspect, the fusion portion is preferably a butt fusion portion or a fusion portion formed by an electric fusion joint.

[0021] <10> The above <6> or <7> In the method for rehabilitating an existing piping relating to the above, when inserting the plastic pipe along the existing piping, it is preferable to insert a tip side of the plastic pipe into the existing piping, position a rear end side of the plastic pipe inside the inlet side vertical shaft, attach a pulley member to a part of the existing piping located inside the inlet side vertical shaft or to the inner wall of the inlet side vertical shaft surrounding the part, attach one end side of a cord body wound around the pulley member to the rear end side of the plastic pipe, and pull up the other end side of the cord body from outside the inlet side vertical shaft with a lifting means to insert the plastic pipe into the existing piping.

[0022] The pulling direction of the cable is changed to horizontal by using a pulling means installed outside the inlet shaft to pull the cable upwards, and the cable pulls the rear end of the plastic pipe toward the inside of the existing piping, allowing the plastic pipe to be inserted inside the existing piping.

[0023] <11> The above <10> In the method for rehabilitating an existing pipe according to the above, it is preferable to wrap a belt member around the end of the existing pipe located inside the inlet side vertical hole, and attach the pulley member to the belt member.

[0024] When attaching the pulley member to the existing pipe, if the end of the existing pipe is located inside the inlet side vertical hole, a belt member can be wrapped around the end of the existing pipe and the pulley member can be attached to the belt member. The cable is wound around the pulley supported by the belt member, and the cable is pulled up by a lifting means, allowing the resin pipe to be inserted into the existing pipe.

[0025] <12> The above <10> In the method for rehabilitating an existing piping according to the above aspect, it is preferable to attach a mounting member to a rear end of the resin pipe and to attach one end of the cable body to the mounting member.

[0026] By attaching one end of the cable to the mounting member attached to the rear end of the plastic pipe, when the cable is pulled, the plastic pipe can be pushed inward through the mounting member into the existing piping. Also, by pulling the plastic pipe with the cable through the mounting member, the plastic pipe can be pushed inward without damaging the rear end of the plastic pipe. Effect of the Invention

[0027] According to the piping structure of the present invention, a new pipeline can be formed inside an existing pipe by providing a rehabilitation pipeline made of a resin pipe joined to the inside of the existing pipe via a fusion joint. Furthermore, if the SDR value, which is the ratio of the outer diameter D to the wall thickness T of the resin pipe, is set to 13.5 or less, sufficient pipe thickness can be ensured, and the method can be applied without problems even if the existing piping is subject to internal pressure, such as drinking water pipes or gas pipes. Of course, the method can also be applied without problems to existing piping that is not subject to large internal pressure, such as sewer pipes. [Brief description of the drawings]

[0028] [Figure 1] 1 is a partial cross-sectional view showing a piping structure of a first embodiment according to the present invention. [Diagram 2] 2 is a partial cross-sectional view showing the state in which an inlet side vertical hole and an outlet side vertical hole have been formed to create the piping structure shown in FIG. 1. [Diagram 3] FIG. 2 is a partial cross-sectional view showing a state in which multiple plastic pipes are inserted into an existing piping from an inlet side vertical hole to create the piping structure shown in FIG. 1. [Figure 4] 2 is a side view showing a state in which resin pipes are butted together via a heater in butt fusion for realizing the piping structure shown in FIG. 1. FIG. [Diagram 5] FIG. 13 is a side view showing a state in which the resin pipes are butted together and heated by a heater in the butt welding process. [Figure 6] 13 is a side view showing a state in which the heater has been removed from between the heated resin pipes in the butt welding process of FIG. [Figure 7] FIG. 13 is a side view showing the state in which the ends of the heated resin pipes are crimped and fused together in the butt welding process. [Figure 8]FIG. 2 is a partial cross-sectional view showing the state in which a plastic pipe that has been extended inside an existing piping is moved to the outlet shaft side in order to realize the piping structure shown in FIG. 1. [Figure 9] 2 is a cross-sectional view showing the process of moving an additional plastic pipe inside an existing piping to realize the piping structure shown in FIG. 1. [Figure 10] FIG. 2 is a cross-sectional view showing the state in which a plastic pipe extended inside an existing piping is fused to a plastic pipe located below the outlet-side vertical hole in order to realize the piping structure shown in FIG. [Figure 11] 1 is a side view showing a state in which a plastic pipe is attached to an electric fusion joint when the electric fusion joint is used in a piping structure according to the present invention; FIG. [Figure 12] FIG. 11 is a side view showing a state in which an electric fusion joint is energized from a controller when an electric fusion joint is used in the piping structure according to the present invention. [Figure 13] FIG. 11 is a side view showing a state in which plastic pipes are fused to each other using an electric fusion joint in the piping structure according to the present invention. [Figure 14] FIG. 1 is a cross-sectional view showing an example of an electric fusion joint useful for implementing the present invention. [Figure 15] FIG. 1 is a perspective view showing an example of a state in which work is being performed using a jig that can be applied to a pipeline rehabilitation method according to the present invention. [Figure 16] FIG. 4 is a perspective view showing the state in which the jig is attached to an existing pipe. [Figure 17] FIG. 4 is a partial cross-sectional view showing the state in which the cable is pulled by a lifting machine using the same jig. [Figure 18] FIG. 11 is a side view showing another example of a jig applicable to the pipeline rehabilitation method according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, a piping structure and a method for rehabilitating an existing piping according to a first embodiment of the present invention will be described with reference to Figs. "First embodiment" FIG. 1 shows a cross section of an existing pipe 1 buried underground, and also shows a state in which a new rehabilitating pipeline (newly installed pipe section) 2 has been formed inside the existing pipe 1 along its length. In the area where the rehabilitated pipeline 2 is formed in Fig. 1, an inlet side pit 3 and an outlet side pit 4 are formed by excavating the ground at a predetermined interval. Also, in an area other than the area between the inlet side pit 3 and the outlet side pit 4, an additional inlet side pit 5 is formed to the side of the inlet side pit 3 shown in Fig. 1.

[0030] 1 is a cross-sectional view of the existing pipe 1 at the time when the rehabilitated pipeline 2 has been formed, and the rehabilitation work can be completed by backfilling the inlet side vertical hole 3, the outlet side vertical hole 4, and the additional inlet side vertical hole 5 from the state shown in Fig. 1. After forming the rehabilitated pipeline 2 inside the existing pipe 1, a filler such as mortar may be filled in the gaps between the inner peripheral surface of the existing pipe 1 and the outer peripheral surface of the rehabilitated pipeline 2, or the inlet side vertical hole 3, the outlet side vertical hole 4, and the additional inlet side vertical hole 5 may be backfilled without filling the gaps from the state shown in Fig. 1 to complete the rehabilitation work. The rehabilitated pipeline 2 is constructed by joining together a number of straight plastic pipes 6. In the joined plastic pipes 6, 6 shown in the first embodiment, their ends 6a are joined together by butt fusion parts 7. The butt fusion parts 7 will be described later, but before that, the plastic pipes 6 will be described in detail.

[0031] The resin pipe 6 is preferably made of a thermoplastic resin such as a polyolefin resin. The resin pipe 6 made of a polyolefin resin has a higher tensile breaking elongation measured according to JIS K 6815-1 and JIS K 6815-3 than a rigid polyvinyl chloride pipe. The tensile breaking elongation of a rigid polyvinyl chloride pipe is 50 to 150%, whereas the tensile breaking elongation of a polyolefin resin pipe is 350% or more. In particular, a high density polyethylene pipe of PE100 has a tensile breaking elongation of 500% or more by the extrapolation method specified in ISO / TR9080, and therefore can be more effectively prevented from being damaged by an earthquake.

[0032] The polyolefin resin is not particularly limited, but suitable examples include polyethylene, polypropylene, polybutene, atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, poly-α-olefin, etc. Among these, it is preferable to adopt polyethylene from the viewpoint of strength, etc. When selecting polyethylene, it is preferable to appropriately select one of low density polyethylene, medium density polyethylene, high density polyethylene, etc. according to the required durability desired for the resin pipe 6. A resin pipe 6 made of polyethylene resin can be used from the viewpoint of not affecting earthquake resistance, durability, water quality, etc. In particular, when the resin pipe 6 is used as a drinking water pipe, a resin pipe made of high density polyethylene is preferable.

[0033] The specific gravity of the thermoplastic resin is not particularly limited, but is, for example, 942 to 953 kg / m 3 The specific heat of the thermoplastic resin is not particularly limited, but is, for example, 1.9 to 2.3 kJ / kg·[K]. The thermal conductivity of the thermoplastic resin is not particularly limited, but is, for example, 0.46 to 0.5 W / m·K. The melt mass flow rate (MFR) of the thermoplastic resin is, for example, preferably 0.1 to 25 g / 10 min, more preferably 0.1 to 10 g / 10 min, and even more preferably 0.29 to 0.45 g / 10 min. When the MFR is equal to or higher than the lower limit, molding becomes easy. When the MFR is equal to or lower than the upper limit, thermal stability can be further improved. MFR can be measured in accordance with JIS K 7210:1999 at a test temperature of 220°C and a test load of 10 kg. The melting point of the thermoplastic resin (ie, the melting temperature of the resin pipe 6) is not particularly limited, but is preferably 150°C to 260°C, and more preferably 180°C to 240°C. The resin material forming the resin pipe 6 may contain, in addition to thermoplastic resin, known additives such as pigments, ultraviolet absorbers, antioxidants, lubricants, and fillers. The resin pipe 6 may be a multi-layer pipe having three or more layers including a metal layer as an intermediate layer. Suitable metal materials for forming the metal layer include, for example, iron, brass, copper, stainless steel, aluminum, titanium, and silver alloy.

[0034] The resin pipe 6 may have a multi-layer structure having a surface layer on at least one of the outer circumferential surface and the inner circumferential surface. For example, by having a surface layer containing ethylene-vinyl alcohol copolymer resin, the resin pipe 6 may be a pipe for any purpose, such as a drinking water pipe, a gas pipe, or a sewer pipe. This is because the surface layer containing ethylene-vinyl alcohol copolymer resin makes it difficult for gases such as hydrogen, oxygen, propane, and butane, and hydrocarbons such as gasoline and benzene to permeate.

[0035] The surface layer may include at least one of inorganic fibers and organic fibers. Examples of inorganic fibers include glass fibers, carbon fibers, silicon-titanium-carbon composite fibers, boron fibers, and metal fibers. Examples of organic fibers include aramid fibers, vinylon fibers, polyester fibers, and polyamide fibers. When the surface layer includes these fibers, the tensile strength of the resin pipe 6 can be increased and thermal expansion can be further suppressed. The surface layer may also include a fluororesin. When the surface layer includes fluorine, resistance (chemical resistance) to acids, alkalis, and the like can be increased. A layer similar to the above surface layer may also be provided inside the wall of the resin pipe 6.

[0036] The SDR value, which is the ratio of the outer diameter D to the wall thickness T of the resin pipe 6, is preferably 13.5 or less. If the SDR value exceeds 13.5, the pipe thickness becomes too thin and there is a risk that the pipe cannot withstand the internal pressure of the fluid when the fluid flows inside. If the SDR value is too low, the pipe thickness becomes too thick and there is a risk that a sufficient flow rate cannot be ensured. For this reason, the lower limit of the SDR value is preferably 6 or more, and more preferably 7.4 or more.

[0037] Generally, in pipe thickness design, for a pipe through which water flows, the relationship between the tensile circumferential stress generated in the pipe due to the internal water pressure (the tensile stress generated in the circumferential direction in the cross section of the pipe) follows the Naday equation shown in equation (1) below. σ=P(Dt) / 2t …(1) formula In equation (1), σ is the tensile circumferential stress generated in the pipe (MPa), P is the internal water pressure (MPa), D is the outer diameter of the pipe (mm), and t is the thickness of the pipe (mm).

[0038] Based on the above-mentioned Naday formula, it is preferable to design the pipe thickness so that the stress generated at the design internal pressure (maximum allowable stress) has a safety factor of 2 for the 50-year creep strength of polyethylene water distribution pipes. For example, this relationship can be expressed by the following formula (2). σ 50 / S1=P d (Dt) / 2t …(2) formula However, in formula (2), σ 50 : 50-year creep strength of polyethylene water distribution pipe (10MPa), S1: σ 50 Safety factor for (here assumed to be 2), P d : Maximum allowable pressure (static pressure 0.75 x water hammer pressure 0.25 = 1.0 PMa) By modifying the above formula (2), the SDR (Standard Dimension Ratio) value can be calculated using the following formula (3). SDR = D / t = 1 + (2σ 50 ) / P d ·S1=1+(2×10) / (1×2)=11…(3) formula

[0039] According to the pipe thickness design for water pipes, which was calculated with a safety factor of 2 as mentioned above, it is found that an SDR value of 11 is favorable, but if the pipe is to be rehabilitated such as polyethylene sewer pipes, where the internal pressure of the pipe can be estimated to be low, an SDR value of 13.5 or less is desirable. Note that if the standard SDR value for polyethylene water pipes is 11, the SDR value when the flow rate drops by 40% (commonly calculated with a flow velocity coefficient of 140 and a hydraulic gradient of 3%) is less than SDR6, so an SDR value of 6 or more is preferable.

[0040] The plastic pipe 6 is a pipe housed inside the existing piping 1, but is a self-supporting pipe, unlike the thin, non-self-supporting pipes used in the prior art with inner pipe linings. Moreover, it is preferable that the plastic pipe 6 be a plastic pipe with little deformation, with an ovality of 5 mm or less. It is preferable that the method of measuring the ovality of the resin pipe 6 conform to the Japan Water Works Association standard: JWWAK144 (polyethylene pipe for water distribution). Measure each dimension with a measuring device such as a vernier caliper at 23±2°C 24 hours or more after the manufacture of the resin pipe, and condition the pipe for 4 hours or more before measuring. In addition, if the temperature measurement is outside of 23±2°C, such as when measuring dimensions outdoors, it is preferable to convert the measured values ​​to dimensions at 23°C based on the following formula (4).

[0041] L 23 ={1+α×(23-t)}×L t …(4) formula In equation (4), L 23 : Dimensions at 23°C (converted value), α: Linear expansion coefficient (1 / °C) (polyethylene pipe for water supply: 12.0×10 -5 ), t: Temperature at time of measurement (℃), L t : Dimensions (measured value) at t℃ For example, in formula (4), if the outer diameter of a straight pipe with a nominal diameter of 100 is measured at an air temperature of 35°C (the resin pipe temperature is also 35°C) and the measured value is 125.9 mm, the converted value at 23°C will be 125.7 mm, as calculated by the following formula. D 23 ={1+12.0×10 -5 ×(23-35)}×125.9=125.7mm

[0042] The resin pipe 6 applied to this embodiment preferably has a flexure rate of 5% or less. The flexure rate is preferably measured in accordance with the Japan Water Works Association standard: JWWA K144 (polyethylene pipe for water distribution).

[0043] In the structure shown in Fig. 1, since the rehabilitating pipeline 2 is constructed inside the existing pipe 1, the outer pipe diameter of the plastic pipe 6 (rehabilitating pipeline 2) needs to be smaller than the inner pipe diameter of the existing pipe 1. It is desirable that the outer pipe diameter (mm) of the rehabilitating pipeline 2 and the inner pipe diameter (mm) of the existing pipe 1 have the relationship shown in Table 1 below. Furthermore, when applying this embodiment, the outer pipe diameter is not particularly limited, but it is preferable to apply it to a rehabilitating pipe with an outer diameter of 315 mm or less. With the outer pipe diameter in this range, fusion is possible with a small amount of heat and the fusion equipment can be made compact, making it easy to install. The inner diameter of the rehabilitated pipeline 2 (plastic pipe 6) is inevitably smaller than the inner diameter of the existing pipe 1. However, considering the current situation at the site where the existing pipe 1 is to be rehabilitated, the existing pipe 1 is a pipe that has been in place for 30 to 50 years, and in Japan, the current population is overwhelmingly smaller than the current population 30 to 50 years ago. Considering this, it is generally considered that there will be no problem in applying the rehabilitated pipeline 2, even if the flow rate is somewhat reduced due to the smaller inner diameter of the rehabilitated pipeline 2.

[0044] [Table 1]

[0045] The nominal diameter (nominal diameter of the resin pipe 6), outer diameter: D, and thickness: t of the rehabilitated pipeline 2 can be selected from the sizes shown in Table 2 below. In Table 2, PTC K 03 indicates the Association standard for polyethylene pipe systems for water distribution (Politec Association standard), and PWA 001 indicates the Association standard for polyethylene pipe systems for building facilities.

[0046] [Table 2]

[0047] The resin pipe 6 preferably has a tensile yield strength of 20 MPa or more, and a tensile elongation at break of 350% or more. The resin pipe 6 preferably has a tensile modulus of 800 to 1100 MPa. The flexural modulus of 1000 to 1200 MPa, and a water pressure breaking strength of 4.0 MPa or more. These specific values ​​can be measured in accordance with the above-mentioned Japan Water Works Association standard: JWWA K144 (polyethylene pipe for water distribution). As will be described later in the rehabilitation method for an existing pipe, since the plastic pipe 6 is pulled and moved a predetermined distance along the length of the existing pipe 1 inside the existing pipe 1 during construction, it is preferable to provide a protective layer on the outer circumferential surface of the plastic pipe 6 to prevent scratches or the like from being caused on the outer circumferential surface of the plastic pipe 6. The protective layer may be provided separately on the outer circumferential surface of the plastic pipe 6, may be integrated therewith, or may be provided separately by a method such as wrapping.

[0048] In the extended resin pipe 6, the butt fused portion 7 at which the ends 6a are fused to each other is formed, for example, according to the procedure shown in Figs. As a preparation process for the butt fusion portion 7, it is preferable to adjust the end surface shape of the end 6a of one plastic pipe 6 to be joined and the end 6a of the other plastic pipe 6 as shown in Figure 4 by a method such as cutting as necessary, and then clean it.

[0049] After cleaning, the end faces of the ends 6a are placed face to face, and a plate-shaped heater (heating body) 8 is sandwiched between the ends 6a, 6a as shown in FIG. 4. Next, electricity is applied to the heater 8 to heat the ends 6a, 6a to a temperature higher than the softening point and lower than the melting temperature for a predetermined time, and the temperature is maintained. After this, the heater 8 is removed from between the ends 6a, 6a as shown in FIG. 6. Then, the ends 6a, 6a in the high temperature state are directly butted together as shown in FIG. 7, and cooled for a predetermined time while maintaining the necessary butting force. The butted parts of the ends 6a, 6a in the high temperature state are deformed into a shape having a bead (build-up part) 6b ​​as shown in FIG. 7, and the end faces are fused together. The bead 6b refers to a part that spreads in a flange shape around the outer periphery of the resin pipe 6 as a result of pressing the ends 6a of the resin pipe 6 against each other while maintaining a high temperature. The portion fused together with the beads 6b, 6b by the butt fusion described based on Figures 4 to 7 can be described as the butt fusion portion 7. Therefore, it can be described as a structure in which the resin pipes 6, 6 are fusion-connected by extension via the butt fusion portion 7 as shown in Figure 7.

[0050] In the piping structure shown in Fig. 1, a rehabilitated pipeline 2 is formed from a plurality of resin pipes 6 that are joined and fusion-connected via these butt fusion sections 7. This rehabilitated pipeline 2 is then installed inside the existing pipeline 1, and the pipeline of the existing pipeline 1 is rehabilitated. The butt fused portions 7 shown in FIG. 1 are all formed by the method for forming the butt fused portions 7 previously described with reference to FIGS.

[0051] (Pipe rehabilitation method) A method for rehabilitating an existing pipe 1 by forming a rehabilitation pipeline 2 shown in FIG. 1 will be described below. Although the explanation will vary slightly depending on whether the existing pipe 1 is a water pipe, a gas pipe, or a sewer pipe, the following will take as an example a case where the existing pipe 1 is buried underground. Fig. 2 shows a state in which only a portion of an existing pipe 1 has already been rehabilitated with a plastic pipe 6. Fig. 2 is drawn to explain the process of forming a rehabilitated pipeline 2 along the entire existing pipe 1 by sequentially joining other plastic pipes 6 to the partially rehabilitated plastic pipe 6.

[0052] As shown in FIG. 2, an inlet side pit 3 and an outlet side pit 4 are formed at a predetermined interval along an existing pipe 1 buried at a predetermined depth in a ground 11 below ground 10. Regarding the installation environment of the existing pipe 1, it is difficult to excavate a wide area along the existing pipe 1. However, if the environment allows the formation of an inlet side vertical hole 3 and an outlet side vertical hole 4 that reach the ground at intervals along the existing pipe 1 into the ground 11 as shown in Figure 2, the pipeline rehabilitation method described below can be applied. In addition, when the existing piping 1 is a sewer pipe, among a plurality of manholes formed at predetermined intervals along the sewer pipe, adjacent manholes may be used as the inlet shaft 3 or the outlet shaft 4.

[0053] As shown in Fig. 2, the outlet side shaft 4 is formed to include the plastic pipe 6 located at the end of the area already rehabilitated with the plastic pipe 6. As an example, when the end 6a of the rehabilitated plastic pipe 6 is viewed in plan, the end 6a is formed to reach the existing piping 1 from the ground 10 so that it is located a sufficient length inside the outlet side shaft 4. In addition, an outlet side access port 1a is formed in the existing piping 1 below the outlet side shaft 4 so as to communicate with the outlet side shaft 4 and the inside of the existing piping 1. By forming the outlet side access port 1a in the peripheral wall of the existing piping 1, the outlet side shaft 4 and the inside of the existing piping 1 are communicated with each other. Also, an inlet side shaft 3 is formed at a position along the existing piping 1 at a predetermined distance from the outlet side shaft 4. The inlet side shaft 3 is formed so as to reach the existing piping 1 below from the ground 10. It is preferable that the inner diameter of the inlet side shaft 3 is approximately the same as that of the outlet side shaft 4 or slightly larger. Once the inlet side shaft 3 is formed, an inlet side working port 1b of the same diameter as the inlet side shaft 3 is formed in the existing piping 1 below it so as to communicate with the inlet side shaft 3 and the inside of the existing piping 1. By forming the inlet side working port 1b in the peripheral wall of the existing piping 1, the inlet side shaft 3 and the inside of the existing piping 1 are communicated with each other. The inner diameter of the inlet side vertical hole 3 can be slightly larger than the length of one of the resin pipes 6. If there is sufficient free space at the position where the inlet side vertical hole 3 is to be formed in the installation environment of the existing piping 1, the inner diameter of the inlet side vertical hole 3 may be formed larger.

[0054] After the inlet side vertical hole 3 is formed, a plurality of, for example, two plastic pipes 6 are inserted into the existing piping 1 through the inlet side vertical hole 3. The length of the plastic pipes 6 used here is a length that allows them to be inserted into the existing piping 1 through the inlet side vertical hole 3 and the inlet side working port 1b. When inserting two plastic pipes 6 into the existing piping 1, it is preferable to adjust the position of the plastic pipes 6 along the internal space of the existing piping 1 as shown in FIG. 3, and accommodate the ends 6a of the two plastic pipes 6 so that they are located at the center of the inlet-side vertical hole 3. After the ends 6a of the two plastic pipes 6 are aligned, the ends 6a of the two plastic pipes 6 are positioned facing each other using a support 13 such as a stand required for butt fusion as shown in FIG. 3. After this, the two plastic pipes 6 are butt fused according to the butt fusion procedure previously described with reference to FIGS. 4 to 7. By butt fusion, the two plastic pipes 6 are joined in a state of being extended via beads 6b, 6b as shown in FIG. 7.

[0055] When butt welding of the two plastic pipes 6 is completed, the two plastic pipes 6 are slid from the inlet side vertical hole 3 side to the outlet side vertical hole 4 side. The leading plastic pipe 6 is moved to a position close to the outlet side vertical hole 4, and the two plastic pipes 6 are slid along the existing piping 1 so that the end (rear end) 6c ​​of the rear plastic pipe 6 is positioned toward the center of the inlet side vertical hole 3.

[0056] After this, a new plastic pipe 6 is again introduced into the existing piping 1 through the inlet side vertical hole 3. Then, the newly introduced plastic pipe 6 is butt fused to the rear end of the rear end side plastic pipe 6 that has previously been butt fused, according to the butt fusion procedure previously described with reference to Figures 4 to 7. As a result, for example, three plastic pipes 6 are introduced and joined into the existing piping 1, as shown in Figure 9. In the manner described above, new plastic pipes 6 are successively introduced from the inlet side vertical hole 3 into the interior of the existing piping 1, and the butt fused plastic pipes 6 are successively fed out toward the outlet side vertical hole 4. Each time a new plastic pipe 6 is butt fused below the inlet side vertical hole 3, a plurality of butt fused plastic pipes 6 can be continuously installed inside the existing piping 1 from the outlet side vertical hole 4 to the inlet side vertical hole 3. This allows a structure in which a plurality of plastic pipes 6 are inserted into the interior of the existing piping 1 and joined together.

[0057] FIG. 8 shows a drawing device H suitable for use when sliding a plurality of joined resin pipes 6 within an existing piping 1. In FIG. The lead-in device H shown in Fig. 8 includes a winch device 20 housed in the outlet-side vertical hole 4 and a lead-in wire (wire) 22 of a predetermined length wound around a winding drum 21 of the winch device 20. The tip side of the lead-in wire 22 is connected to the leading resin pipe 6 of the resin pipes 6 which are joined together by butt welding. In the rehabilitation work of the existing pipe 1, for example, after the outlet side vertical hole 4 and the inlet side vertical hole 3 are formed, the winch device 20 is installed on the bottom side of the outlet side vertical hole 4. Then, the lead-in wire 22 of the winch device 20 is pulled out from the winding drum 21 so that the tip of the lead-in wire 22 reaches the lower side of the inlet side vertical hole 3, and the tip of the lead-in wire 22 is attached to the leading plastic pipe 6 to be connected in a multiple-extension manner. When connecting multiple plastic pipes 6 in a multiple-extension manner, the leading plastic pipe 6 is pulled by the lead-in wire 22 of the winch device 20 while sliding it within the existing pipe 1, whereby the extended plastic pipe 6 can be easily moved along the existing pipe 1.

[0058] When the leading resin pipe 6 that has been butt-welded first reaches the resin pipe 6 present in the outlet-side pit 4 as shown in Fig. 10, the ends 6a of the two adjacent resin pipes 6 are made to face each other. In this state, the ends 6a of the two resin pipes 6 located below the outlet-side pit 4 are positioned to face each other using the support tool 13 required for butt fusion previously shown in Fig. 3. Thereafter, the two adjacent resin pipes 6 below the outlet-side pit 4 can be butt-welded according to the procedure for butt fusion previously described with reference to Figs. 4 to 7. By the above-mentioned work, the pipe renewal work using a plurality of resin pipes 6 for the existing piping 1 between the inlet side vertical hole 3 and the outlet side vertical hole 4 can be completed.

[0059] After completing the pipeline rehabilitation work of the existing piping 1 by extending and connecting a plurality of plastic pipes 6 from the position of the outlet side vertical hole 4 to the position of the inlet side vertical hole 3, the pipeline rehabilitation work of the remaining area is carried out. That is, the pipeline rehabilitation work of the area to the right of the inlet side vertical hole 3 shown in FIG. 10 is carried out. To achieve this, an additional entrance side vertical hole 5 and an additional entrance side work opening 1c are formed not between the exit side vertical hole 4 and the entrance side vertical hole 3, but at a position spaced apart on the opposite side of the exit side vertical hole 4 (to the side in Figure 10) from the entrance side vertical hole 3. The work so far has involved introducing a plastic pipe 6 starting from the inlet vertical hole 3 toward the outlet vertical hole 4, thereby rehabilitating the existing piping 1. In the next stage, an additional entrance side pit 5 is formed at a position opposite to the side facing the exit side pit 4 from the entrance side pit 3 previously used as the starting point, and at a predetermined distance from the entrance side pit 3 used as the starting point.

[0060] 2 shown above shows a state in which an additional inlet-side pit 5 has been formed in advance at a position separated from the inlet-side pit 3 in the early stages of rehabilitation work. The additional inlet-side pit 5 may be formed in the early stages of rehabilitation work, or after all the plastic pipes 6 have been laid between the inlet-side pit 3 and the outlet-side pit 4 as shown in FIG. 10, or during the intermediate stage of extending and connecting the plastic pipes 6 between the inlet-side pit 3 and the outlet-side pit 4. In the work up to this point, the plastic pipe 6 has been installed by sequentially extending it from the inlet side vertical hole 3 toward the outlet side vertical hole 4, but in the work from here on, it will be necessary to install a plastic pipe 6 between the additional inlet side vertical hole 5 and the inlet side vertical hole 3 that was previously used as the starting point.

[0061] In the work from this point, the inlet side vertical hole 3 that was previously used as the starting point is regarded as the outlet side vertical hole, and multiple plastic pipes 6 are sequentially introduced into the existing piping 1 from the additional inlet side vertical hole 5. Then, multiple plastic pipes 6 are extended and connected by butt welding below the additional inlet side vertical hole 5, and are sequentially sent to the inlet side vertical hole 3 side. When the head of the extended plastic pipe 6 reaches the plastic pipe 6 below the inlet side vertical hole 3, the ends of the plastic pipes 6, 6 that have reached and are facing each other are butt fused to each other as described above with reference to Figure 10. By these operations, multiple plastic pipes 6 can be arranged between the bottom of the additional inlet side vertical hole 5 and the inlet side vertical hole 3, and the pipeline rehabilitation of the existing piping 1 in this area is completed. As described above, by forming additional inlet side vertical holes 5 successively and intermittently along the length of the existing pipe 1, the entire pipe line can be rehabilitated for the corresponding length of the existing pipe 1.

[0062] In the example described with reference to Figures 1 to 10, the existing pipe 1 is long. However, when the existing pipe 1 is relatively short, it can be dealt with by providing an outlet side vertical hole 4 at one end in the length direction of the existing pipe 1 to be rehabilitated, and providing an inlet side vertical hole 3 at the other end in the length direction. In this case, the plastic pipe 6 is sequentially introduced from the inlet side vertical hole 3 to extend and connect the plastic pipe 6, and when the tip of the extended plastic pipe 6 reaches the outlet side vertical hole 4, the rehabilitation work of the existing pipe 1 is completed. In addition, in the case of sewer pipes, there may be a structure in which the direction of the sewer pipe changes at the location of a manhole. In this case, it is possible to deal with this by forming an outlet side vertical hole 4 or an inlet side vertical hole 3 at the location of one manhole, and forming an inlet side vertical hole 3 or an outlet side vertical hole 4 at the location of another manhole. Therefore, the rehabilitation work of existing piping described above can also be applied to the rehabilitation of existing piping that has a bent route through a manhole.

[0063] In the first embodiment described above, the resin pipes 6 are connected in the required number via the butt fusion portions 7 and used to rehabilitate the existing piping 1 . When the resin pipe 6 is extended and connected, it may be extended and connected via a fusion part using an electric fusion joint, instead of the butt fusion part 7. As an example, an electric fusion joint 30 has a single-tube resin pipe main body 31 made of the same resin as that constituting the resin pipe 6, and an electric heating wire (not shown in Fig. 11) arranged in a spiral shape on the inner peripheral surface of the resin pipe main body 31. The resin pipe main body 31 has a length and inner diameter that allow the end of the resin pipe 6 to be joined to be inserted by a required length. The end of the electric heating wire arranged in a spiral shape on the inner peripheral surface of the resin pipe main body 31 is connected to a terminal 32 protruding on the outer peripheral side of the resin pipe main body 31.

[0064] As shown in FIG. 11, the ends 6a of the resin pipes 6, 6 are inserted into one and the other of the resin pipe main body 31 in the length direction, and as shown in FIG. 12, the connection wire 34 of the controller 33 for current supply is connected to the terminal 32. After this, the controller 33 supplies electricity to the heating wire to generate heat. After a predetermined time with the required amount of electricity is supplied, the electricity supply is stopped and the wire is cooled, and the resin pipes 6, 6 can be joined by adding them together through the fusion part generated by the electric fusion joint 30 as shown in FIG. 13. By supplying electricity to the heating wire, the inner surface of the resin pipe main body 31 and the outer surface of the resin pipe 6 are mutually fused, so that the resin pipes 6, 6 can be fused together as if they were being added together. Since the inside of the resin pipe main body 31 cannot be shown in FIG. 13, the position of the fusion part 35 formed between the resin pipe main body 31 and the resin pipe 6 is shown by a chain line. The fusion part 35 is formed with a predetermined width all around the contact part between the outer surface of the resin pipe 6 and the inner surface of the resin pipe main body 31.

[0065] In the second embodiment, a joining structure in which plastic pipes 6 are fused to each other by a fusion portion 35 using an electric fusion joint 30 is adopted, instead of the joining structure using the butt fusion portion 7 in the previous first embodiment. The piping structure and pipeline rehabilitation method of the second embodiment can be realized by replacing all of the butt fusion sections 7 previously shown in FIGS.

[0066] In fusion joining of the plastic pipes 6, 6 using the electric fusion joint 30, a controller 33 shown in Fig. 12 is used to accurately input a specified amount of power to the heating wire, generating a specified amount of heat and enabling fusion joining. Therefore, if a fusion section 35 using the electric fusion joint 30 is used instead of the butt fusion section 7 shown in Figs. 1 to 10, a worker performing fusion work inside the entrance side vertical hole 3 or the exit side vertical hole 4, which have limited space, can perform fusion joining reliably without causing fusion defects.

[0067] FIG. 14 shows an example of the structure of an electric fusion joint that can be applied to the above-mentioned second embodiment. The electric fusion joint 30 shown in Fig. 14 has a fusion part on the inner circumferential surface of a resin pipe body made of thermoplastic resin into which a connecting resin pipe is inserted. The fusion part is formed by inserting an electric heating wire into a spiral notched groove formed on the inner circumferential surface of the resin pipe body. Specifically, the electric fusion joint 30 includes a plastic tube body 50, a first heating portion 51, first terminals 52, 53, a first indicator 55, a second heating portion 56, second terminals 57, 58, and a second indicator 59.

[0068] The resin pipe body 50 made of a thermoplastic resin is formed into a hollow cylindrical shape. As the thermoplastic resin constituting the resin pipe body 50, it is preferable to use a polyolefin resin similar to that of the resin pipe 6 described above.

[0069] Examples of methods for molding the resin pipe body 50 include extrusion molding and injection molding. In particular, extrusion molding makes it easy to mold the resin pipe body 50 into a long shape or with a large diameter. The resin pipe body 50 is formed to have the same inner diameter and the same outer diameter from one end to the other end in the length direction. An end 6a of one of the resin pipes 6 to be connected is inserted into one end of the resin pipe body 50, and an end 6a of the other of the resin pipes 6 to be connected is inserted into the other end of the resin pipe body 50.

[0070] (First heating part) A first heating portion 51 is provided on the inner circumferential surface of the resin pipe main body 50 at one end in the longitudinal direction. The first heating portion 51 has a first heating wire 61 inserted into a first notched groove formed in a spiral shape on the inner peripheral surface side of the plastic pipe body 50. The opening portion of the first notched groove may have a spiral shape with the pipe axis O of the plastic pipe body 50 as the central axis and the distance from the central axis to the inner peripheral surface as the radius, for example.

[0071] The first terminals 52, 53 are provided on the peripheral surface of one end of the resin pipe main body 50 at a distance from each other in the circumferential direction. The first terminals 52, 53 are provided to pass electricity through the first heating wire 61 when electrically fusing the connecting resin pipe 6 to the first heating part 51. For simplicity of illustration in Fig. 14, the wire withdrawal hole and the first terminals 52, 53, etc. are shown in the same positions.

[0072] The first indicator 55 is embedded in a first recess 54 provided on the outer circumferential surface of the plastic pipe main body 50. The first indicator 55 protrudes radially outward from the first recess 54 during electrical fusion in which power is supplied to the first heating wire 61 via the first terminals 52, 53. The protrusion of the first indicator 55 makes it possible to confirm that the first heating portion 51 has been electrically fused to the plastic pipe 6 to be connected. The first indicator 55 may be molded integrally with the resin pipe main body 50 using the same material, or may be formed using a material different from that of the resin pipe main body 50 and assembled to the resin pipe main body 50.

[0073] (Second heating part) A second heating portion 56 is provided on the inner circumferential surface of the resin pipe main body 50 at the other end in the longitudinal direction. The second heating portion 56 has a second heating wire 62 inserted into a second notched groove formed in a spiral shape on the inner peripheral surface side of the plastic pipe body 50. The opening portion of the second notched groove may have a spiral shape with the pipe axis O of the plastic pipe body 50 as the central axis and the distance from the central axis to the inner peripheral surface as the radius, for example.

[0074] The second heat generating portion 56 is configured in substantially the same manner as the first heat generating portion 51 . In this embodiment, the winding direction and the number of turns of the spiral formed by the first heating wire 61 and the second heating wire 62 are not particularly limited.

[0075] The second terminals 57, 58 are provided on the peripheral surface of the other end of the resin pipe body 50 at a distance from each other in the circumferential direction. The second terminals 57, 58 are provided to pass electricity through the second heating wire 62 when electrically fusing the connected resin pipe 6 to the second heating portion 56. For simplicity of illustration in Fig. 14, the wire withdrawal hole and the second terminals 57, 58, etc. are shown in the same positions. The second indicator 59 is embedded in a second recess 60 provided on the outer circumferential surface of the plastic pipe main body 50. The second indicator 59 protrudes radially outward from the second recess 60 during electrical fusion in which power is supplied to the second heating wire 62 via the second terminals 57, 58. The protrusion of the second indicator 59 makes it possible to confirm that the second heating portion 56 has been electrically fused to the plastic pipe 6 to be connected. As described above, the second heat generating portion 56 is configured in substantially the same manner as the first heat generating portion 51.

[0076] The first heating wire 61 and the second heating wire 62 may be made of nichrome, iron-chromium alloy, copper-nickel alloy, copper-manganese alloy, iron-nickel alloy, manganese, copper-nickel-manganese alloy, nickel-chromium alloy, chromel, etc. The first heating wire 61 and the second heating wire 62 may be coated or uncoated. 14, the first heating wire 61 is arranged in a spiral shape so as to have a folded-back portion at a position toward the center in the longitudinal direction of the resin pipe body 50. Therefore, electricity can be passed through the first heating wire 61 by using the first terminals 52 and 53. The second heating wire 62 is arranged in a similar manner, and electricity can be passed through the second heating wire 62 by using the second terminals 57 and 58.

[0077] The electric fusion joint 30 shown in FIG. 14 can be used as the electric fusion joint 30 previously described with reference to FIG. 13, and can be suitably used when extending and fusion-joining plastic pipes 6, 6. With this electric fusion joint 30, it is possible to confirm that fusion joining has been performed reliably by checking the protrusions of the indicators 55, 59, so that the plastic pipes 6, 6 can be reliably fusion joined without causing fusion defects. Therefore, when the existing piping 1 is rehabilitated using the resin pipe 6, the pipe can be rehabilitated reliably without generating any poorly joined portions.

[0078] The existing pipe 1 and the rehabilitation pipeline 2 described above have both been described as examples of pipes that are buried underground, but the present invention can also be applied to cases where the existing pipe 1 is not underground but is installed under a structure or along a bridge, etc. As described above, even if a site does not allow for wide-area excavation along the existing pipe 1, the present invention can be applied without any problems as long as it is possible to form an inlet side vertical hole 3 and an outlet side vertical hole 4, or an additional inlet side vertical hole 5 in addition to these.

[0079] (Modification of the Pipeline Rehabilitation Method) FIG. 15 shows a state in which a jig suitable for use in carrying out the pipeline rehabilitation method according to the present invention is used, and FIG. 16 is a perspective view showing an example of a state in which the jig is attached to an existing pipe. 2 to 14, a plurality of plastic pipes 6 were connected by splicing using butt fusion parts 7 or electric fusion joints 30, and the connected plurality of plastic pipes 6 were inserted into the existing pipe 1. In the previous explanation, as shown in FIG. 8, the drawing device H was installed in the outlet side vertical hole 4, and the plastic pipe 6 was slid and drawn into the existing pipe using the winch device 20 and the lead-in wire 22. Alternatively, instead of or in addition to the winch device 20, a pulley jig shown in Figs.

[0080] Pulley jig 70 shown in Figures 15 and 16 is a jig to be installed in inlet-side vertical hole 3 shown in Figure 8, and can be applied when end 1A of existing piping 1 slightly protrudes into inlet-side vertical hole 3. Pulley jig 70 includes belt member 71 attached to end 1A of existing piping 1, and pulley member 72 attached to belt member 71. The belt member 71 has a C-shaped belt body 71A that is fitted circumferentially around the end 1A of the existing piping 1, and locking pieces 71B formed to protrude from both circumferential ends of the belt body 71A so as to rise from the end of the belt body 71A. When the belt body 71A is fitted circumferentially around the existing piping 1, the locking pieces 71B, 71B protrude outward from the peripheral surface of the existing piping and are integrated with the belt body 71A so as to face each other with a space between them. For example, a metal belt can be used as the belt body 71A, and the locking piece 71B made of a metal plate can be fixed to the end of the metal belt by a method such as welding.

[0081] The locking pieces 71B, 71B are formed with insertion holes 71c at positions corresponding to each other when facing each other, and a connection bolt 73 is inserted through the opposing insertion holes 71c, 7c. A nut 74 is screwed into the threaded portion of the connection bolt 73, and by adjusting the screwing position of the nut 74 relative to the connection bolt 73, the locking pieces 71B, 71B are biased in directions approaching each other. This biasing force tightens and fixes the belt body 71A to the outer periphery of the end of the existing piping 1. In the locking piece 71B, an attachment hole 71d is formed at a position adjacent to the insertion hole 71c, and a pulley member 72 is attached via a ring-shaped connector 75 inserted into this attachment hole 71d. The pulley member 72 includes a pulley body 72B rotatably supported between disk-shaped support plates 72A, 72A, and a cord 76 such as a rope can be wound around the outer periphery of the pulley body 72B. The pulley member 72 is connected to the locking piece 71B via a connector 75, and is supported so that the orientation of the pulley body 72B can be appropriately changed while connected to the connector 75.

[0082] FIG. 15 shows a state in which the tip side of the plastic pipe 6 is inserted inside the existing piping 1 in the inlet side vertical hole 3 , and the rear end side of the plastic pipe 6 is positioned inside the inlet side vertical hole 3 . A cover plate-like mounting member 77 is attached to the rear end side of the resin pipe 6 so as to contact the rear end and close the opening at the rear end. This mounting member 77 is made of a resin disk with a diameter slightly larger than the outer diameter of the resin pipe 6, and mounting pieces 77A are formed at several points around the outer periphery of the mounting member 77. In addition, a U-shaped locking wire 78 is connected to two adjacent mounting pieces 77A around the circumference of the mounting member 77.

[0083] As shown in Figure 16, the belt body 71A is wrapped around the end 1A of the existing piping 1 so that the locking pieces 71B, 71B face each other, and the screwing position of the nut 74 relative to the connecting bolt 73 is adjusted to tighten and fix the belt member 71 to the end 1A of the existing piping 1. As shown in Fig. 17, a lifting machine (lifting means) 80 such as a crane truck is placed on the road above the entrance pit 3, and a rope 76 such as a towing wire attached to the lifting machine 80 is lowered into the entrance pit 3. It is preferable that the rope 76 has a locking member such as a hook (not shown) at its tip. While winding the tip side of the cable 76 from above the pulley member 72 around the pulley body 72B, the direction of the cable 76 is changed by approximately 90 degrees to a horizontal direction, and the locking member at the tip of the cable is locked to the locking wire 78 along the plastic pipe 6. This makes it possible to connect the tip (one end) of the cable 76 to the rear end of the plastic pipe 6.

[0084] After the connection of the cables 76 is completed, the cables 76 are lifted up by the lifting machine 80. The cables 76 extending in the vertical direction below the lifting machine 80 are lifted up, while the cables 76 extending in the horizontal direction after being changed in direction by the pulley body 72B are pulled horizontally so as to pull the tip side (one end side) of the cables 76 toward the pulley member 72. As a result, the rear end side of the plastic pipe 6 can be moved toward the pulley member 72 by the cable 76 via the locking wire 78 and the mounting member 77. This allows the plastic pipe 6 to be inserted inside the existing piping 1. Since the lifting force of the lifting machine 80 can be set to a large value of several tons to about 10 tons, the pushing force when pushing the plastic pipe 6 into the existing piping 1 can also be adjusted to a sufficiently large force. Furthermore, even when pushing in with such a large force, the mounting member 77 is in uniform contact with the rear end surface of the plastic pipe 6, so there is no risk of scratching the rear end of the plastic pipe 6 and there is no risk of damaging the plastic pipe 6.

[0085] Once the plastic pipe 6 has been inserted so that the rear end of the plastic pipe 6 is positioned near the end 1A of the existing piping 1, the towing operation by the lifting machine 80 is terminated and the tip of the cable 76 is removed from the retaining wire 78. Next, a new resin pipe 6 to be connected next to the rear end of the resin pipe 6 is butt-connected as in the example described above, or is extended by connection using an electric fusion joint. Thereafter, a mounting member 77 is attached to the rear end of the newly added plastic pipe 6, and the locking portion at the tip of the cable 76 is locked to the locking wire 78, so that the new plastic pipe 6 can be pulled again by the lifting machine 80. From this state, the new plastic pipe 6 can be inserted into the existing piping 1 by pulling it with the lifting machine 80 in the same manner as described above. By repeating the above-described operations, the resin pipe 6 can be successively extended and inserted into the inside of the existing piping 1, and finally the structure shown in FIG. 1 can be obtained.

[0086] According to the method described above, the insertion work of the plastic pipe 6 can be carried out using the lifting machine 80 by the simple steps of setting up a lifting machine 80 on the road, attaching a pulley member 72 to the end A of the existing piping 1 in the inlet side vertical tunnel 3, and attaching the tip of the cable body 76 to the rear end of the plastic pipe 6 via the pulley member 72. Furthermore, this work can be carried out as long as the entrance pit 3 is large enough to install the plastic pipe 6 horizontally, so it can be carried out reliably even in narrow areas or on sites with limited space where a large-diameter entrance pit 3 cannot be formed due to road conditions or surrounding buildings.

[0087] 18 shows a second modified example in which a plastic pipe 6 is pushed in using a pulley member 72, and as in this example, a pulley body 72B may be directly attached to an end 1A of an existing pipe 1 via an attachment member 81, and a cable 76 may be wound around the pulley body 72B. The pulley body 72B is supported so as to be rotatable around its central axis of rotation, with the central axis of rotation oriented horizontally. As shown in FIG. 18, the tip end of the wound cable 76 may be directly connected to a mounting member 77 provided so as to contact the rear end of the resin pipe 6 . The structure shown in FIG. 18 also makes it possible to configure a pulley jig that can push the plastic pipe 6 into the inside of the existing piping 1 by pulling the cable 76 with a lifting machine 80 installed on the ground. The structure shown in FIG. 18 is preferably applied when the wall thickness of the existing piping 1 is sufficiently large and the strength of the existing piping 1 is sufficiently high.

[0088] In the embodiment described above, the lifting machine 80 is used as the lifting means for lifting the cable 76, but a winding device such as a winch can also be used as the lifting means. In the embodiments described so far, examples have been described in which the pulley member 72 is directly or indirectly attached to the existing piping 1, but the pulley member 72 may also be attached to the inner wall of the inlet side shaft 3 surrounding the existing piping 1. When the inner wall of the inlet side shaft 3 is a metal wall, a mounting base or the like can be fixed by a method such as welding, and the pulley member 72 can be attached to this mounting base via a hook, ring, or the like. [Explanation of symbols]

[0089] 1...Existing piping, 1A...End portion, 1a...Exit side work port, 1b…Inlet side work opening, 1c…Additional inlet side work port, 2...Rehabilitation pipeline (newly installed piping section), 3... Entrance side pit, 4...Exit side pit, 5…Additional entrance shaft, 6...Resin pipe, 7...Butt fusion part, 30... Electric fusion joint, 35...Fusion part, 71...belt member, 72...pulley member, 76...Striata, 77...Mounting member, 80...Lifting machine (lifting means).

Claims

1. A piping structure for rehabilitating existing piping, The rehabilitating pipeline is housed inside the existing piping and is formed by joining a plurality of plastic pipes together via fusion joints, and the SDR value, which is the ratio of the outer diameter D to the wall thickness T of the plastic pipe, is 13.5 or less. Piping structure.

2. The ellipticity of the resin tube is 5 mm or less. The piping structure according to claim 1 .

3. The deflection rate of the resin pipe is 5% or less. The piping structure according to claim 1 .

4. The resin tube is made of a polyolefin resin. The piping structure according to claim 1 .

5. The fusion portion is a butt fusion portion or a fusion portion by an electric fusion joint. The piping structure according to claim 1 .

6. A method for rehabilitating existing piping installed underground or under a structure, At each of the positions spaced apart along the existing piping, an outlet side vertical hole and an inlet side vertical hole are formed to connect to the ground and the existing piping therebelow; An inlet side work port is formed in the existing piping so as to communicate with the inlet side vertical hole, and an outlet side work port is formed in the existing piping so as to communicate with the outlet side vertical hole, Next, a method of rehabilitating an existing piping includes inserting multiple plastic pipes of a predetermined length into the interior of the existing piping through the inlet side vertical hole and the inlet side work port, extending the multiple plastic pipes inserted into the existing piping through the fused parts, and moving them toward the outlet side work port to form a rehabilitated pipeline.

7. A plurality of the resin pipes are extended from the existing piping below the inlet side vertical hole toward the existing piping below the outlet side vertical hole, and reach the bottom of the outlet side vertical hole, An additional inlet side shaft is formed at a position along the existing piping, starting from the inlet side shaft, on the opposite side to the side where the outlet side shaft is formed, at a predetermined distance, and an additional inlet side work opening communicating with the additional inlet side shaft is formed in the existing piping below the additional inlet side shaft; Insert a plurality of plastic pipes into the existing piping from the additional inlet side vertical hole and the additional inlet side work port, extend the required number of plastic pipes, and allow the tip side of the extended plastic pipe to reach below the inlet side vertical hole that is the starting point, and fuse the tip side of the extended plastic pipe to the plastic pipe that is present below the inlet side vertical hole that is the starting point. The method for rehabilitating an existing pipe according to claim 6.

8. The SDR value, which is the ratio of the outer diameter D to the wall thickness T of the resin tube, is 13.5 or less. The method for rehabilitating an existing pipe according to claim 6 or 7.

9. The fusion portion is a butt fusion portion or a fusion portion by an electric fusion joint. The method for rehabilitating an existing pipe according to claim 6 or 7.

10. When inserting the plastic pipe along the existing piping, a tip side of the plastic pipe is inserted into the existing piping, and a rear end side of the plastic pipe is positioned inside the inlet side vertical hole, and a pulley member is attached to a part of the existing piping located inside the inlet side vertical hole or to the inner wall of the inlet side vertical hole surrounding the part, one end side of a cable body wound around the pulley member is attached to the rear end side of the plastic pipe, and the other end side of the cable body is pulled up from the outside of the inlet side vertical hole by a lifting means to insert the plastic pipe into the existing piping. The method for rehabilitating an existing pipe according to claim 6 or 7.

11. A belt member is wound around the end of the existing piping located inside the inlet side vertical hole, and the pulley member is attached to the belt member. The method for rehabilitating an existing pipe according to claim 10.

12. A mounting member is attached to the rear end of the resin pipe, and one end of the cable is attached to the mounting member. The method for rehabilitating an existing pipe according to claim 10.

Images