JP3756876B2 - Propulsion method and earthquake-resistant propulsion pipe fittings used in it - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-open-cut propulsion method for embedding underground fluid transport pipes used for water supply, gas, sewerage, and the like, and an earthquake-resistant propulsion pipe fitting suitable for use therein.
[0002]
[Prior art]
There is a pipe-in-pipe method as one method of burying fluid transport pipes such as ductile cast iron pipes. This method is a method of inserting a new pipe into an existing old pipe and is widely used because it does not require excavation.
[0003]
The pipe joint in the pipe-in-pipe method that has been conventionally employed is, for example, as shown in FIG. The joint 100 is called a PII type joint, and includes a receiving port 101, an insertion port 102, a lock ring 103, a set bolt 104, a rubber ring 105, and the like.
[0004]
FIG. 9 shows an outline of the conventional pipe-in-pipe method, and a new pipe P having a smaller diameter is inserted into an existing pipe P ′ buried between the start pit S and the arrival pit R. . A hydraulic jack J is installed in the starting pit, the rear portion of the hydraulic jack abuts against the reaction force receiver H, and the front portion presses the new pipe P via the push angle B. The new pipe P is sequentially joined by inserting the insertion port 102 at the tip end thereof into the receiving port 101 at the rear end part of the preceding new pipe, and is pushed into the existing pipe. A leading sled K is attached to the tip of the leading new tube.
[0005]
The new pipes P,... Are joined as follows. First, the lock ring 103 and the rubber ring 105 are attached to the inner surface of the receiving port. Thereafter, the hydraulic jack J is operated, the insertion port 102 is inserted into the receiving port 101, and the set bolt is tightened. As a result, the succeeding new pipe is joined to the rear part of the preceding new pipe whose rear end faces the starting pit. When the succeeding new pipe is joined, it is pressed with the hydraulic jack J, and the joined series of pipes are advanced toward the reaching pit. The propulsive force of the hydraulic jack is transmitted by contact between the lock ring 103 and the end face of the lock ring groove 107. In the figure, a new pipe is inserted into the existing pipe, but a method of inserting a new pipe into the pipe of the propulsion work by the pipe-in-pipe method is also performed.
[0006]
Next, FIG. 10 shows a propulsion method using a UF type ductile pipe slightly different from the above, and this UF type ductile pipe for propulsion method includes a receiving port 201, an insertion port 202, a rubber ring 205, a lock ring 203, a set. The bolt 204, the push wheel 208, the bolt 209, the joint rod 210, the exterior concrete 211, and the like. When joining the UF type ductile tube, first, the lock ring 203 is expanded and attached to the lock ring groove 207 on the inner surface of the receiving port. Next, after the insertion port is inserted into the receiving port by the propulsion jack, the set bolt 204 is tightened, and the lock ring 203 is stuck to the lock ring groove 207. Thereafter, the rubber ring 205, the push ring 208, and the joint rod 210 are attached from the inner surface side and tightened with the bolt 209. Finally, mortar is filled in the bolt part on the inner surface of the receiving port.
[0007]
The UF type ductile pipe is pushed from the starting pit S to the reaching pit R while being pushed in by the propulsion jack J from the start pit S or by excavating with the leading pipe. The propulsive force at this time is transmitted through the engagement between the lock ring 203 and the lock ring groove 207.
[0008]
[Problems to be solved by the invention]
In the case of the PII type ductile pipe for the pipe-in-pipe method, since the lock ring 103 and the end face of the lock ring groove 107 are in contact with each other as shown in FIG. It cannot move in the direction of entering the receiving port 101. For this reason, there exists a problem that the coupling | bonding does not satisfy | fill the performance as an earthquake-resistant pipe which needs to expand-contract in both directions. Note that when a large pulling force acts on the joint due to an earthquake or the like, the lock ring 103 and the lock ring groove 107 are engaged to exert a detachment preventing force, which is normally used as an earthquake resistant joint. It can withstand half the pulling force of type ductile tubes, SII type ductile tubes, and NS type ductile tubes.
[0009]
In the case of the UF type ductile tube, the lock ring 203 is in the lock ring groove 207 when the propulsion is finished. When an earthquake or the like occurs in this state and a pushing force or a pulling force acts on the joint, the joint portion functions as a detachment preventing joint, and the joint expansion amount necessary for the earthquake resistant joint is not provided. Further, since the joint is joined from the inner surface of the pipe, there is a problem that only a pipe having a nominal diameter, that is, a diameter of 700 mm or more, that can be inserted into the pipe by the worker can be joined. The applicable diameter of the UF type ductile tube is Φ700 to 2600 mm.
[0010]
As described above, since none of the conventional ductile pipes for the propulsion method is provided with the amount of expansion and contraction necessary for an earthquake-resistant joint, there is a high possibility that the joint portion is damaged due to the occurrence of an earthquake.
[0011]
Then, this invention makes it a subject to embed a pipe | tube in the state which has sufficient expansion-contraction amount as an earthquake-resistant joint.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a thrust transmission material on the outer peripheral surface of the insertion port, and this thrust transmission material maintains the middle of the required length that allows the insertion port to move within a range that does not come off in the receiving port. When a pressing force greater than the propulsive force is applied due to an earthquake or the like, the pressing force is greater than the maintaining force of the thrust transmission material, and the middle of the required length that can move within the range that does not pass through the insertion slot It was released so that the insertion slot was pushed further into the receptacle.
[0013]
That is, in the present invention, when the pipe is connected and buried in the basement, a propulsive force can be transmitted between the pipe insertion port and the receiving port, and when the pressing force larger than the propulsive force is applied, the insertion port is further provided. A configuration is adopted in which a thrust transmission material that can be pushed in is interposed and propulsion is transmitted to the preceding pipe through the thrust transmission material.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described more specifically based on the embodiments of the present invention shown in the drawings.
[0015]
FIG. 1 is a cross-sectional view showing the structure of a pipe joint according to the present invention. This pipe joint 1 is an NS type joint that is usually used as a seismic joint for waterworks. Become. The insertion port 2 is integrally provided with an insertion port projection 5 on the outer peripheral surface of the distal end portion of the ductile tube 4. When a large pulling force is applied to the pipe joint due to an earthquake or the like, the insertion port protrusion 5 and a lock ring 17 described later are engaged with each other, thereby preventing the insertion port from coming out from the receiving port. The insertion port protrusion 5 is provided in a ring shape on the entire outer periphery of the insertion port 2. A flange 7 is integrally provided at a position near the rear of the insertion slot 2. Reference numerals 8,... Are backup reinforcing ribs provided on the back surface of the flange 7 at appropriate intervals. The flange 7 and the reinforcing rib 8 are made of metal and fixed to the outer peripheral surface of the insertion port 2 by welding or the like.
[0016]
The receiving port 3 is formed by expanding the rear portion of the ductile tube 4 in a substantially funnel shape, and a rubber ring mounting groove 10 and a lock ring groove 12 are provided on the inner surface thereof. An inward flange 13 is formed at the rear end portion of the receiving port 3, and its end surface is formed as a flat surface 13 a perpendicular to the axial direction. A rubber ring 15 for sealing is fitted in the groove 10, and a lock ring 17 which is formed by being split into one part in the lock ring groove 12 is provided via a rubber ring 18 for centering the lock ring. Is fitted. 19 is an interior material and 20 is exterior concrete.
[0017]
A thrust transmission member 25 is interposed between the flange 7 of the insertion port 2 and the inward flange 13 of the receiving port 3. As shown in FIG. 2, the thrust transmission member 25 is formed as an annular integral body. This thrust transmission material is formed as a low-expanded polystyrene ring that has a wide plastic region and the elastic limit stress changes by changing the expansion ratio. The material may be another resin material having a desired thrust transmission force and contractibility, and the shape is practically a ring shape having an appropriate thickness and width as shown in the drawing.
[0018]
The thrust transmission material will be described in more detail. Since the thrust transmission material 25 is elastically deformed by a compressive force that is about the driving force during construction, the thrust is transmitted, but the amount of distortion does not remain. Further, when a compressive force greater than the elastic limit stress is applied, the amount of strain increases in the plastic region. Thereafter, when a compressive force of a certain level or more is applied, the progress of strain stops with a predetermined thickness remaining. When the thrust transmission material is a foam material, the final thickness in the state where the elastic limit stress, the range of the plastic region, and the strain have progressed can be adjusted by the expansion ratio. The following conditions can be considered as a method for setting the expansion ratio.
[0019]
When the applied pressing force is about the driving force, it is a stress value within the elastic limit stress, so the foaming ratio is set so that the elastic limit stress σ ₁ has the following relationship (in order to transmit the driving force normally) , Prevent the thrust transmission material from plastic deformation).
σ ₁ > (F / A) = σ _max where F: thrust, A: area of the thrust transmission portion, and σ _max : stress generated in the thrust transmission material.
[0020]
Next, when a large pushing force is applied to the joint due to an earthquake or the like, the thrust transmission material is in the plastic region, so the amount of distortion of the thrust transmission material increases. Assuming that the pushing force generated during this earthquake is the same as 0.3d (tf) (d: nominal diameter), which is the seismic joint disconnection prevention force, as shown in FIG. Then, the thrust transmission material of the pushing margin amount L + L ₁ is compressed to the length L ₁ . At this time, if L is set to be 1% of the tube length, the push-in margin can be secured. Needless to say, by interposing this thrust transmission material, it is possible to prevent stress concentration at the time of curve propulsion, which is the original purpose of use of the thrust transmission material.
[0021]
6 and 7 show stress-strain curves in the case where low foam polystyrene is used as the material of the thrust transmission material. The strain increases with a predetermined compression force, and the amount of indentation can be secured by the strain in the compression direction. This low-expanded polystyrene is mainly composed of polystyrene obtained by adding a foaming agent such as propane, has a wide plastic region, and has the property of changing the elastic limit stress by changing the expansion ratio. FIG. 7 shows the relationship between the expansion ratio and the stress and strain, and shows the relationship between the expansion ratio of different types of A and B types of expanded polystyrene and their mechanical properties.
[0022]
The construction method of the joint 1 will be described as follows. First, as shown in FIG. 3A, the propulsive force transmission material 25 is deposited on the outer peripheral portion of the insertion slot 2. On the other hand, as shown in FIG. 5B, a rubber ring 15 and a lock ring 17 are attached to predetermined positions of the receiving port 3, and the insertion port 2 is inserted into the receiving port 3. After that, if the pipe 2 is a pipe-in-pipe construction method, the pipe with the insertion slot 2 inserted into the receptacle 3 is sequentially inserted into the sheath pipe, and if it is a propulsion construction method, the pipe is sequentially inserted while excavating with the top pipe. . In this state, as shown in FIG. 3C, the thrust transmission member 25 is sandwiched between the flange 7 of the insertion port 2 and the inward flange 13 of the receiving port 3, and the propulsive force by the hydraulic jack is It is transmitted to the preceding pipe via the thrust transmission member 25. After the completion of the propulsion, the thrust transmission material is left as it is.
[0023]
FIG. 5 shows an embodiment different from the above. In this joint, the lock ring 37 of the receiving port 33 is fitted in the lock ring groove 34 provided on the rear end side of the receiving port with respect to the rubber ring 15. A projection 35 of the insertion slot 32 with which this is engaged is formed at an intermediate portion between the lock ring and the rubber ring. The lock ring 37 is fixed by a set bolt 38. The rubber ring 15 is fitted in the rubber ring groove 36. The other parts are generally the same as in the previous figure.
[0024]
As described above, the thrust transmission member 25 may be any member as long as it can transmit the thrust necessary for propulsion and can secure the amount of expansion and contraction of the joint. It is not limited to those. For example, instead of the foamed resin, it is also possible to use a porous ceramic, a metal sintered body, a metal net or the like.
[0025]
【The invention's effect】
As is apparent from the above description, according to the present invention, a sufficient amount of expansion and contraction is ensured after pipe embedment, which is extremely effective as a seismic joint.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment of an earthquake-resistant propulsion pipe joint according to the present invention. FIG. 2 shows the thrust transmission material, (a) is a cross-sectional view, and (b) is a front view. FIG. 4 is an operation diagram of the embodiment, (a) is a normal state, (b) is a state where a large pressing force is applied. FIG. 5 is a cross-sectional view of another embodiment. ] Graph showing stress-strain curve of low-expanded polystyrene [Fig. 7] Graph showing stress-strain curve of various materials [Fig. 8] Cross-sectional view of conventional pipe joint [Fig. 9] Explanatory drawing of propulsion method [Fig. 10] Sectional view of other conventional pipe fittings [Explanation of symbols]
1 Pipe Fitting 2 Insert 3 Receiving Port 5 Protrusion 7 Flange 15 Rubber Wheel 17 Lock Ring 25 Thrust Transmission Material

Claims (2)

When the tube insertion ports 2 and 32 are inserted into the preceding tube receiving ports 3 and 33, lock rings 17 and 37 are provided on the inner surface of the receiving port, and protrusions 5 and 35 are provided on the outer periphery of the insertion port. Thus, the projection is engaged with the lock ring in the pulling-out direction of the insertion port, and a seismic pipe joint that secures a margin for the insertion port tip to be pushed in the insertion direction of the insertion port. It is a propulsion method for burying in the basement while connecting the pipe so that it can move the required length within the range that does not come out in the pipe axis direction with respect to the receiving port,
A thrust transmission material is provided on the outer peripheral surface of the insertion port, and the thrust transmission material is used to propel the insertion port while maintaining the middle of the required length that can move within the above-mentioned range. When a large pressing force is applied, the pressing force is greater than the maintenance force of the thrust transmission member, and the middle maintenance of the required length that can move within the range that does not escape the insertion port is released, and the insertion port becomes a receiving port. A propulsion method characterized by being pushed further. Lock rings 17 and 37 are provided on the inner surfaces of the tube receiving ports 3 and 33, and protrusions 5 and 35 are provided on the outer peripheral portions of the insertion ports 2 and 32. When the insertion port is inserted into the receiving port and connected, The protrusion engages with the lock ring in the direction of pulling out the insertion slot, and a margin is secured in which the tip of the insertion slot is pushed in the insertion direction of the insertion slot. The insertion port and the receiving port in the propulsion method for burying in the basement while being connected to the tube so that the insertion port can move the required length within a range that does not come out in the tube axis direction with respect to the receiving port. Pipe fittings,
A thrust transmission material is provided on the outer peripheral surface of the insertion port, and the thrust transmission material is used to propel the insertion port while maintaining the middle of the required length that can move within the above-mentioned range. When a large pressing force is applied, the pressing force is greater than the maintenance force of the thrust transmission member, and the middle maintenance of the required length that can move within the range that does not escape the insertion port is released, and the insertion port becomes a receiving port. A seismic propulsion pipe fitting that is further pushed in.

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