JP2015143454A - Concrete jacked pipe for pipe jacking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concrete jacked pipe capable of being more inexpensively and easily manufactured than a steel-concrete composite jacked pipe, with shear-resistant strength equivalent to an intermediate level between the shear-resistant strength of the steel-concrete composite jacked pipe and the shear-resistant strength of the concrete jacked pipe.SOLUTION: On the outer periphery of a concrete jacked pipe 1 body of a concrete jacked pipe forming a pipeline by pushing out the pipes into the ground while sequentially connecting the pipes to a rear end side by a jacking machine, a plurality of circular ring-shaped wrap-around materials 6 made of a strip-shaped material such as band steel are provided at intervals in an axial direction of the jacked pipe 1 body.

Description

  The present invention relates to a concrete propulsion pipe for a propulsion method in which a pipe is formed by pushing the pipe into the ground while sequentially connecting the pipe to the rear end side by a propulsion device.

  Conventionally, a vertical pipe called a vertical shaft is dug deeply into the ground, and a propulsion machine equipped with a huge push jack is used to form a pipe line by sequentially connecting propulsion pipes of appropriate length from the vertical shaft into the ground. The propulsion method is widely implemented.

  In recent years (structures such as building foundations, gas, water, subways, etc. have increased in structures buried in the ground, and the propulsion method has diversified, and at the same time, the curve propulsion method that avoids those obstacles has increased.

  In the curve propulsion method, in order to curve the pipe line to the left and right, a method is adopted in which a cushion material is attached to the upper and lower sides of the joint of the propulsion pipe so that the pipe joint is easily bent (for example, Patent Document 1).

  In this curve propulsion, when the pipe is pushed with the main pusher jack of the propulsion unit, the jack is arranged on the left and right of the pipe, and the cushion material of the joint portion is arranged on the upper and lower sides of the pipe. A linear shear force acts.

  In general, the load carrying capacity of the propulsion pipe is designed to withstand the loading force due to the vertical load and the propulsive force, but the propulsive force necessary for the propulsion pipe is designed to handle the compressive stress of the concrete. It can be said that the propulsion pipe that makes use of the characteristics of concrete with large compressive stress is the most suitable pipe material for the propulsion method.

  However, when an axial shear force acts on the propulsion pipe, the shear strength is about 1/10 or less of the compressive stress, which is a serious problem in the propulsion method.

  In order to reduce the radius of curvature in curved propulsion, it is necessary to increase the angle between the adjacent propulsion pipes. At that time, the joint part must be opened widely outside the bend. In terms of performance, there is a limit to the degree of opening in the joint.

  For this reason, in order to reduce the outward opening of the bend between the propulsion pipes and reduce the radius of curvature of the pipeline, a measure is taken to shorten the length of the propulsion pipe and increase the number of joints (for example, Patent Document 2) When an axial shearing force acts on a short propulsion pipe, the shear resistance of the concrete decreases, and cracking due to extrusion during propulsion becomes a problem.

  In particular, in the recent propulsion method, it is necessary to shorten the length per one propulsion pipe because the curve propulsion of the pipe line is complicated and the curvature needs to be reduced. For the above reasons, the propulsion force during propulsion There is an increased risk of cracking.

  As a method for solving such a problem, in order to increase the shear resistance of the propulsion pipe, a concrete layer was formed on the inner peripheral surface of the steel pipe by centrifugal molding, and as a result, the outer peripheral surface of the concrete pipe was covered with a steel shell. Steel-concrete composite propulsion pipe (for example, Patent Document 3) having a shape, and steel concrete composite that uses prestressing by constraining the expansion by the steel pipe using the concrete part of the steel-concrete composite propulsion pipe. A propulsion pipe (for example, Patent Document 4) has been developed.

  In general, centrifugal reinforced concrete pipes (fume pipes) are roughly classified into external pressure pipes, internal pressure pipes and propulsion pipes depending on the application and the burying method.

  Conventionally, the propulsion pipe is often used as a sewer and is not an internal pressure pipe adapted to the internal water pressure. This was because the internal water pressure basically did not act on the sewer.

  Moreover, the internal pressure pipe in which water pressure acts on the inner surface of the pipe is used for agricultural waterways, industrial waterways, and the like, and a cut pipe that is laid by cutting the ground has been used. The reason for this is that an excavation groove is formed in the laying site, and the inner pressure pipe is installed in the burial area to refill the pipe.Therefore, there is little damage to the outer surface of the pipe during construction, and the outer surface of the pipe is the most important during internal water pressure action. This is because there is no damage.

  On the other hand, the propulsion pipe is advanced by inserting an excavator from the inside to the front end side, excavating the ground on the propulsion direction side, and pressurizing in the propulsion direction from the rear end side. It has been considered that the outer surface of the pipe is easily damaged due to a continuous wear action between the natural grounds and is not suitable for an internal pressure pipe.

  Further, since the propulsion pipe is about 15% to 20% thicker than the open cut pipe, it is usual to increase the centrifugal force for compaction during centrifugal molding or lengthen the centrifugal molding time. For this reason, it is easy to form a water channel that is dehydrated during centrifugal molding, and the water permeability of the concrete may be greater in the propulsion pipe than in the open-cut pipe, which is also a cause of being unsuitable for the internal pressure pipe.

  Furthermore, in general, the internal pressure pipe often has a chemical prestress structure obtained by restraining expanded concrete with reinforcing reinforcing bars in order to increase the tensile strength of the concrete (for example, Patent Document 5).

  However, in recent years, the depth of propulsion work has progressed, and there is a growing demand for internal water pressure to act on propulsion pipes when the embedding depth of propulsion pipes is deep or when it is applied to rainwater storage pipes. Examples of the propulsion pipe corresponding to the internal pressure include a steel pipe inserted into a centrifugal reinforced concrete pipe (for example, Patent Document 6) and a steel pipe concrete synthetic steel pipe whose outer peripheral surface is covered with a steel shell (for example, Patent Document 4).

  The above-described conventional propulsion pipe corresponding to internal pressure has a problem of high cost because it is a composite structure of steel pipe and concrete in which a steel pipe is inserted or whose outer peripheral surface is covered with a steel shell.

  In addition, the conventional internal pressure pipe with a chemical prestress structure obtained by constraining expanded concrete with reinforcing reinforcing bars is effective for chemical prestressing because the concrete located outside the reinforcing reinforcing bars on the outer surface of the pipe is unconstrained. There was a drawback that it was difficult to act on.

  As a solution to this problem, it is a centrifugal reinforced concrete pipe that does not use a steel pipe, can be used as an internal pressure pipe, and as a chemical prestress structure, it can increase the tensile strength of concrete and reduce the pipe thickness. Corresponding centrifugal molded reinforced concrete propulsion pipes have been developed (for example, Patent Document 7).

JP 2013-23846 A JP 2001-311386 A JP 2011-117525 A JP 2008-1753364 A JP 2002-355808 A JP 2005-256463 A JP 2011-247337 A

  As described above, in concrete propulsion pipes, the shorter the overall length, the smaller the shear resistance due to extrusion force, and there is a limit to its use for curve propulsion with a small curvature.

  On the other hand, the steel-concrete composite propulsion pipe has a shear resistance that is several steps higher than that of the concrete propulsion pipe, and can be propelled longer with a small radius of curvature. There is a problem that the entire propulsion pipe is expensive due to costs, welding work costs for forming, and deterioration in workability such as mold assembly work due to an increase in the weight of the steel pipe.

  Moreover, although the intensity | strength including the shear stress of a steel concrete composite propulsion pipe is not required, the field where the intensity | strength is insufficient with the conventional concrete propulsion pipe also exists. However, at present, there is a problem that an expensive steel-concrete composite propelling pipe has to be used at a site where a concrete propelling pipe cannot be used.

  The present invention does not require the strength of the conventional steel-concrete composite propulsion pipe, but in view of the problem that the concrete propulsion pipe lacks the strength, particularly the axial shear resistance, it is an intermediate shear resistance between the two. The purpose of providing concrete propulsion pipes for propulsion methods that are strong, low-cost and easy to manufacture compared to steel-concrete composite propulsion pipes, and that are centrifugally formed reinforced concrete propulsion pipes with improved internal pressure performance. It is.

    The feature of the concrete propulsion pipe for propulsion method according to claim 1 for solving the conventional problems as described above is that a pipe is formed by pushing the pipe into the ground while sequentially connecting the pipe to the rear end side by a propulsion unit. In the concrete propulsion pipe for propulsion method, the outer circumference of the concrete propulsion pipe main body is provided with a plurality of body wrapping materials in the shape of a circular ring made of a band-shaped material such as steel strip at intervals in the axial direction of the propulsion pipe main body That is.

  The invention according to claim 2 is characterized in that, in addition to the structure of claim 1, the material of the body winding material is a corrugated shape in which uneven strips are formed in the width direction, or a concrete pipe body side such as a striped steel plate having protrusions on the surface. It exists in being comprised from the strip steel plate which has an unevenness | corrugation in the surface integrally.

  The feature of the invention described in claim 3 is that, in addition to the configuration of claim 1 or 2, the entire surface area of the body-wound material is an area ratio of 40% to 60% of the surface area of the propelling tube body.

  The feature of the invention described in claim 4 is that, in addition to the configuration of claim 3, the interview ratio of the body winding material includes a steel material portion constituting a plug portion and a socket portion constituting a joint of the propulsion pipe.

According to a fifth aspect of the present invention, in addition to the structure according to any one of the first to fourth aspects, the propulsion pipe body has an inner surface side concrete layer made of expanded concrete on the inner surface side and the inner surface side concrete on the outer surface side. It has an outer surface side concrete layer made of concrete that is less expansible than the layer, and it is made impermeable by adding a water repellent made of a drying shrinkage reducing agent between the inner surface side and the outer surface concrete layer. An intermediate mortar layer made of high-density mortar is interposed, and the concrete layers on the inner surface side and the outer surface side each have a reinforcing bar cocoon-reed structure having reinforcing bar rods inside thereof, and the outer surface side concrete layer is made of a high-strength admixture. Is that the compressive strength at 14 days of age is 85 N / mm ² or more and the tensile strength is 8 N / mm ² or more.

  The concrete propulsion pipe for a propulsion method according to the present invention, as set forth in claim 1, propels a plurality of winding members in the shape of a circular ring made of a band-shaped material such as band steel on the outer periphery of a concrete propulsion-pipe main body. By providing the pipe body with an interval in the axial direction, the body winding material for reinforcing concrete pipes is lighter in weight than conventional steel-concrete composite propulsion pipes, making welding easier and centrifugal forming. The installation in the mold is easy, and the cost can be reduced.

  In addition, the fracture load becomes larger than that of a concrete propulsion pipe having no conventional steel shell, and a propulsion pipe having an intermediate strength between the steel-concrete composite propulsion pipe and the concrete propulsion pipe can be obtained at a low cost.

  According to the present invention, the material of the body winding material as described in claim 2 is integrally provided with irregularities on the surface on the concrete tube main body side such as a corrugated shape in which irregularities are formed in the width direction or a striped steel plate having projections on the surface. By comprising from a strip steel plate, the strong adhesion with a concrete part is obtained and the effect of a body winding material installation becomes large.

  According to the present invention, the steel-concrete composite propulsion pipe and the concrete propulsion pipe have a surface area of 40% to 60% of the surface area of the propulsion pipe body. Propulsion pipes with intermediate strength can be obtained at low cost.

  In the invention according to the fourth aspect of the present invention, the interview ratio of the body winding material includes the insertion portion constituting the joint of the propulsion pipe and the steel portion constituting the socket portion, so that the joint conventionally used Combined with the steel shell of the part, effective reinforcement is made.

According to the present invention, the propulsion pipe body has an inner surface side concrete layer made of expanded concrete on the inner surface side, and an outer surface side made of concrete having less expansibility compared to the inner surface side concrete layer on the outer surface side. Having a concrete layer, interposing an intermediate mortar layer made of high-density mortar made impermeable by adding a water repellent made of a drying shrinkage reducing agent between the concrete layers on the inner surface side and the outer surface side, The concrete layers on the inner surface side and the outer surface side each have a reinforced cocoon-reed structure having reinforcing bar rods inside thereof, and the outer surface side concrete layer has a compressive strength of 85 N at an age of 14 days by adding a high-strength admixture. / mm ² or more, by the tensile strength was 8N / mm ² or more, the conventional centrifugal molding rebar conc such pressure response according to references 7 Compared to over preparative propulsion tube, more pressure corresponding performance is enhanced.

It is a longitudinal section showing the first example of the propulsion pipe concerning the present invention. It is the sectional view on the AA line in FIG. It is a fragmentary sectional view which shows the coupling part of the propulsion pipe shown in FIG. It is a fragmentary sectional view which shows the other example of the body winding material of the Example shown in FIG. It is a longitudinal cross-sectional view which shows the example of centrifugal forming of the propulsion pipe | tube shown in FIG. The loading method for the propulsion pipe in Experiment 1 is shown. Case 1 is a state in which the position of the cushion material and the position of the jack are diagonal, and Case 2 is a uniform pusher with a highly rigid push wheel in front of the jack. In the pushing state, Case 3 is a perspective view showing a state where the jack is pushing the position of the cushion material. It is a graph which shows the relationship between the loading position in Experiment 1, and crack strength. It is a graph which shows the relationship between the loading position in Experiment 2, and crack strength. It is a front view which shows the shear test apparatus in Experiment 3. (A) to (e) show specimen Nos. 1-No. FIG. 10 is a graph showing the relationship between strain generated in a tube and load in Experiment 3. Specimen No. 1-No. It is a graph which shows the relationship between the distortion | strain and load which generate | occur | produce in the pipe body in the external-pressure test which performed 5 by the method according to Japan Sewerage Association standard ASWAS A-2. The 2nd Example which implemented this invention to the concrete propelling pipe for propulsion methods corresponding to the internal pressure which carried out the internal pressure is shown, (a) is a vertical side view, (b) is a vertical front view. (A)-(c) is a longitudinal front view which shows the manufacturing process of the internal-pressure corresponding | compatible centrifugal forming reinforced concrete propulsion pipe which concerns on this invention.

  Next, an embodiment of the present invention will be described based on a first example shown in the drawings.

  1 and 2 show a concrete propulsion pipe for a propulsion method according to the present invention. In this propulsion pipe 1, a socket part 3 made of a steel cylinder 3a projects from one end of a concrete pipe main body part 2. The socket portion 3 is formed to have the same diameter as the outer peripheral surface of the tube main body portion 2.

  An insertion portion 4 having a smaller diameter is formed at the other end of the tube main body portion 2. As shown in FIG. 3, the insertion portion 4 is formed to have a diameter that can be fitted in the socket portion 3 at the end of the propulsion pipe that is connected in the axial direction during construction of the propulsion method by interposing a water stop packing 5. The insertion portion 4 and the socket portion 3 constitute a joint between the propulsion pipes.

  A cylindrical steel shell 4 a is placed on the outer periphery of the insertion portion 4 so as to extend over the tube main body portion 2. Note that the outer diameter of the end portion of the steel shell 4 a on the tube main body 2 side is the same as that of the tube main body 2.

  A plurality of steel body wrapping materials 6 are fixed around the body of the tube main body 2, that is, between the steel shell 4 a of the insertion portion 4 and the steel cylinder 3 a for socket. ing. For example, a belt-shaped steel material, that is, a steel strip that is bent in a circular shape and welded at both ends, can be used as the body wrapping material 6, and the thickness direction of the belt steel plate is set in the radial direction of the tube main body 2 as shown in FIG. The diameter of the outer peripheral surface is the same as that of the outer peripheral surface of the tube main body 2. The strength of the body wrapping material 6 is not limited as long as it does not plastically deform, that is, does not yield, even if a shearing force acts on the concrete of the tube main body portion to cause a crack. Further, a nonferrous metal material having a comparable strength or a nonmetal material such as a carbon fiber sheet may be used.

  The strip steel plate used for the body wrapping material 6 may have a flat plate shape as shown in FIG. 1, but as shown in FIG. 4 (a), a corrugated shape in which uneven strips 7 are formed in the width direction, or FIG. As shown, a striped steel plate having protrusions 8 on the surface is preferable for increasing the adhesion strength of the pipe body 2 to the concrete.

  Further, a plurality of body winding materials 6 are used in consideration of the length of the tube body 2. According to the experiment described later, 40% to 60% of the tube body 2 is covered, including the steel shell 4a of the insertion portion 4, the steel cylinder 3a for the socket, and the body winding material 2, and the tube body 2 It has been found that it is preferable that the exposed concrete portion 6 be formed on the surface.

  In addition, as shown in FIG. 5, the manufacture of the propulsion pipe 1 according to the present invention is performed on the inner peripheral surface of the centrifugal mold 40 by the steel shell 4a of the insertion portion 4 described above, the steel cylinder 3a for the socket, and the body winding. The material 2 is set at a predetermined position, the reinforcing bar 11 is set at a predetermined position inside, and the concrete 11 is poured into the centrifugal mold 40 and rotated at a predetermined speed to be formed by centrifugal molding.

Next, a comparative experiment assuming a propulsion pipe according to the present invention, a conventional concrete propulsion pipe, and a steel-concrete composite propulsion pipe will be described.
Experiment 1 (reference experiment)

  In this test, the relationship between the position of the cushioning material at the time of propulsion and the cracking resistance strength due to the pressurizing position by the jack was performed by changing the length of the pipe.

  FIG. 6 shows a state in which a cylindrical concrete specimen is pressed from both end faces, the upper part of the concrete specimen showing the position of the cushion material, and the lower part showing the pressure position by the jack.

  In Case 1 in FIG. 6, the position of the cushion material and the position of the jack are diagonal, and the shear force is most likely to act on the tube body. Case 2 is a highly rigid push wheel in front of the Case 1 jack. A state in which the tube is pushed evenly and Case 3 indicates a state in which the jack is pressing the position of the cushion material. The test specimen was a reinforced concrete pipe having an inner diameter of 350 mm and a thickness of 50 mm and a length of 100, 150, 300 mm.

  The crack load resistance in this case was as shown in the graph of FIG.

  In Case 3, since the loading method is relatively close to the compressive stress of concrete, the loading force until cracking is large, but in Case 1, a shearing force acts, so it can be seen that the loading force is also significantly reduced.

  In general, a push ring is inserted between the main push jack and the propulsion pipe over the entire circumference of the end, so that when the pressure is applied via Case 1 such as Case 1, the pipe is subjected to a pure shearing action. There is no load force like Case1. If anything, it is considered to be close to Case2.

  However, in Case 2, the loading force at the same position as Case 3 also acts, but as in Case 1, since the shearing force prevails, the loading force becomes small, and it is understood that cracks are likely to occur in the tube.

As described in the background art section, in the case of a propulsion pipe for curve propulsion, the length of the pipe is often shortened. In this case, even if it is pushed through a push ring as in Case 2, it is a tubular body. It was found from the results of this experiment that shearing force was generated and cracking occurred.
Experiment 2 (reference experiment)

  A loading test of a concrete pipe and a steel-concrete composite propulsion pipe (synthetic steel pipe) in which a steel plate is wound around the concrete was performed in the same loading state as Case 1 and Case 2 described above. The result was as shown in FIG.

Looking at Case 2 in the figure, it can be seen that when the steel pipe is wound around the concrete and the case where the concrete is not compared, the loading force until the crack is clearly increased is increased.
Experiment 3 (Comparative test between the present product and concrete pipe)

Table 1 shows the results of a shear test in the state of Case 1 shown in FIG. 9 in which the area ratio of the body wound material 2 wound around the concrete cylindrical tube was changed. In the figure, reference numeral 20 is a specimen, 21 is a bottom receiving beam, 22 is a top holding beam, 23 is a loading beam, and 24 is a weight.

  In addition, the used concrete pipe 9 has an inner diameter of 1000 mm, a thickness of 100 mm, and a length of 400 mm. No. 1 has no reinforcement 6 as shown in FIG. No. 2 is obtained by integrating a body winding material 6 having a width of 50 mm on the outer periphery of the upper end portion as shown in FIG. No. 3 was obtained by integrating three body wound members 6 having a width of 50, 70, and 50 mm as shown in FIG. No. 4 was obtained by integrating four body-wound members 6 having a width of 50 mm as shown in FIG. 5 shows an area ratio of 100% with respect to the surface of the concrete pipe 9 whose entire circumference is covered with the steel pipe 6a as shown in FIG.

  The crack load in the table is a load in which a bending stress acts on the test specimen by loading and the member first cracks. The breaking load indicates a load when the load of the pressure tester is no longer increased.

  Further, the area ratio of 40% is the central concentration of No. 3, and the area ratio of 50% is No. 3. Four equal arrangements were tested.

  As a result of the test, it has been found that the initial crack load does not have a large difference in yield strength depending on the state of reinforcement, and the fracture load increases as the area ratio of the steel strip increases.

  The reason why there was no significant difference in the crack load is that the initial crack in Case 1 is due to bending tensile stress, and the reinforcing effect of the strip steel plate is small against bending tensile stress.

  However, if the area of reinforcement by the strip steel plate is large in the process of shifting to the shear crack after the initial crack has entered, the crack is dispersed, and the subsequent crack does not proceed.

  If the strain due to cracks generated in the tube exceeds 10,000 μm, it is considered that the cracks are structurally serious.

  Furthermore, the relationship between the strain generated in the tube and the load is as shown in the graph of FIG. 11, and the reinforcement of the entire circumference is approximately four times the yield strength compared to the case where there is no reinforcement or the interview ratio is 12.5%. When the reinforcing area of the strip steel sheet is 40% and 50%, it was found that the steel sheet has approximately twice the yield strength.

  In the experiment, the pipe length was 1/3 of the pipe outer diameter, and it was carried out under the severe conditions of loading with Case 1, and the state of Case 2 (normal propulsion state) and the pipe length became longer. In this case, it is clear from FIG. 7 that this yield strength is further increased.

Moreover, the test body used for the shear test of Case 1 was subjected to an external pressure test by a method according to ASWAS A-2 (Japan Sewerage Association Standard), and the occurrence of cracks and the breaking load at that time were measured. The results were as shown in Table 2 and FIG.

  From these results, it was found that those with reinforcement of 40% and 50% of the interview ratio, compared to those without reinforcement or with an interview ratio of 12.5%, have increased proof strength against vertical loads equal to or greater than the entire circumference. .

  From the above results, the area ratio of the total surface area of the wound material and the surface area of the propelling pipe body in the present invention is preferably 40% or more, and preferably less than 60% from the viewpoint of manufacturing cost.

  In the above example, the steel shell 4a is covered on the outer periphery of the insertion portion 4, but the present invention is a propulsion in which the concrete is exposed without using the steel shell 4a in the insertion portion. It may be a concrete propulsion pipe for construction methods.

  Next, a second embodiment in which the present invention is applied to a concrete propelling pipe for a propulsion method corresponding to internal pressure formed by centrifugal molding will be described with reference to FIGS.

FIG. 13 shows a concrete propulsion pipe for a propulsion method corresponding to an internal pressure which is centrifugally molded corresponding to the internal pressure of the second embodiment according to the present invention. The propulsion pipe 30 is the same as the first embodiment except that the pipe body 2 in the first embodiment described above has a structure corresponding to the internal pressure, and the same portions are denoted by the same reference numerals and the description thereof is omitted.
The pipe body 2 of this embodiment has a three-layer structure of an outer surface side concrete layer 31, an inner surface side concrete layer 32 and an intermediate mortar layer 33 between both concrete layers 31 and 32.

  The outer surface side concrete layer 31 is made of high strength and less expansible concrete mixed with a high strength admixture, and the inner surface side concrete layer 32 is made of expanded concrete mixed with an expanding material. Reinforcing bar rods 34 and 34 are embedded in both the concrete layers 31 and 32.

The intermediate mortar layer 33 is composed of highly dense mortar imparted with water repellency.
Next, a method for manufacturing this propulsion pipe will be described.

  As shown in FIG. 14 (a), a centrifugal mold 40 used for manufacturing a conventional centrifugal reinforced concrete propelling pipe is used. In the mold 40, reinforcing bar rods 34 are installed at positions where a necessary concrete cover thickness can be obtained from the inner and outer surfaces of the formed propulsion pipe.

In this state, the concrete for forming the outer surface side concrete layer 31 described above is placed while rotating the mold 40 at a predetermined speed. This concrete is made of high strength concrete composed mainly of sand, aggregate made of gravel, ordinary Portland cement and water, and a high strength admixture. Table 3 shows examples of the concrete composition of the outer surface side concrete layer 31.

In this way, after the concrete placement of the outer surface side concrete layer 31 to a predetermined thickness, as shown in FIG. 14B, mortar for forming the intermediate mortar layer 33 is placed on the inner surface. This mortar uses a high-density mortar in which sand, cement and water are main materials and a water repellent material is added thereto. Table 4 shows an example of the mortar composition of the intermediate mortar layer 33.

Next, as shown in FIG. 14 (c), concrete for forming the inner surface side concrete layer 32 is placed inside the intermediate mortar layer 33. For this concrete, expanded concrete to which an expansion material is added is used instead of the high-strength admixture compounded in the concrete of the outer surface side concrete layer 31 described above. Table 5 shows an example of the composition of concrete used for the inner surface side concrete layer 32.

The meanings of the symbols in Tables 1 to 3 are as follows.
Maximum dimension: Maximum gravel dimension W / (C + SM), W / C, W / (C + Gp): Water cement ratio S / a: Fine aggregate ratio W: Water,
C: Ordinary Portland cement,

SM: High-strength admixture (trade name Supermix manufactured by Taiheiyo Material Co., Ltd. in the examples)

Gp: expansion material (trade name zipkar manufactured by Taiheiyo Material Co., Ltd.)
S: Sand G: Gravel
SP: Water reducing agent (Product name: 8000S, manufactured by Pozzolith in the examples)
P: Total powder amount (indicating C + SM, C + Gp, C)

  Water repellent: Drying shrinkage reducing agent (trade name Tetragard AS20 manufactured by Taiheiyo Material Co., Ltd. in the examples)

Table 6 shows the mold rotation conditions at the time of molding the concrete layers and the mortar layers.

After molding in this way, a product is obtained by demolding after steam curing at a temperature of 60 to 70 ° C. for 3 to 5 hours.

Table 7 shows the material properties of the respective layers 1 to 3 of the centrifugal reinforced concrete propulsion pipe manufactured as described above.

  In this centrifugal reinforced concrete propulsion pipe, by making it into a multi-layered form with concrete and mortar of each of the above blends, damage between the pipe outer surface and natural ground during propulsion is handled by the strength of the outer concrete layer 31. Moreover, the water path at the time of centrifugal molding is interrupted by the intermediate mortar layer 33, and imperviousness necessary as an internal pressure pipe is ensured.

Furthermore, since expanded concrete is used for the inner surface side concrete layer 32, it expands over time after the concrete is solidified. At this time, the outer side of the inner surface side concrete layer is restrained by the outer surface side concrete layer 31 which is a high-strength reinforced concrete layer. The tensile strength is increased, and the tube thickness can be reduced accordingly.
Example of Internal Pressure Test Next, an internal pressure comparison test example of a conventional embedded collar type propulsion pipe, a conventional propulsion pipe corresponding to internal pressure of Reference Document 7, the propulsion pipe of the first embodiment, and the propulsion pipe of the second embodiment will be described.
Table 8 shows the results of internal pressure tests on various propulsion pipes having an inner diameter of 800 mm.

“NO.1 E type propulsion pipe” in the table is “embedded collar type propulsion pipe corresponding to internal pressure of 0.4 Mpa (megapascal)”, and “No.2 E type JIP pipe” is the waist material in the second embodiment. Reinforced concrete propulsion pipes that do not use the "No. 3 E-type band-wound pipe" are the propulsion pipes of Example 1, and "No. 4 E-type JIP / band-wound hybrid pipes" are with the body winding material of the second example. The propulsion pipe corresponding to the internal pressure is shown.

No. No. 1 conventional single reinforcing bar does not cause water leakage at 0.4 Mpa, but water leakage occurs at 0.5 Mpa. In the propulsion pipe (double rebar) corresponding to the internal pressure of 2, there is no abnormality at 0.5 Mpa, but water leakage occurs at 0.6 Mpa.

Furthermore, no. No. 3 of the propulsion pipe with the body winding material of the second embodiment corresponding to the internal pressure has no abnormality at 0.6 Mpa, and water leakage occurs at 0.7 Mpa. In the propulsion pipe corresponding to the internal pressure with the body winding material of No. 4 in the second example, there was no abnormality at 0.8 Mpa, and water leakage occurred at 0.9 Mpa.

From this result, in the propulsion pipe of the second embodiment according to the present invention, no. No. 2 propulsion pipe and No. 2 Compared with the propulsion pipe with the body winding material of No. 3 in the first embodiment, the internal pressure compatibility is improved by 0.1 Mpa.

DESCRIPTION OF SYMBOLS 1 Propulsion pipe 2 Pipe | tube main-body part 3 Socket part 3a Steel cylinder 4 Insertion part 4a Steel shell 5 Packing 6 Body winding material 7 Uneven rib 8 Projection 9 Concrete pipe 10 Centrifugal formwork 11 Reinforcing bar 12 Concrete 20 Specimen 21 Beam 22 Upper surface presser beam 23 Loading beam 24 Weight 30 Propulsion pipe 31 Outer surface side concrete layer 32 Inner surface side concrete layer 33 Intermediate mortar layer 34 Reinforcement rod 40 Centrifugal molding formwork

Claims (5)

In concrete propulsion pipe for propulsion method that forms a pipeline by pushing the pipe into the ground while sequentially connecting the pipe to the rear end side with a propulsion machine,
For the propulsion method, characterized in that the outer periphery of the concrete propellant tube body is provided with a plurality of body-wound materials in the form of a circular ring made of a strip-shaped material such as steel strip, spaced apart in the axial direction of the propellant tube body Concrete propulsion pipe.   The material of the body winding material is comprised from the strip | belt steel plate which has an unevenness | corrugation integrally in the surface at the side of a concrete pipe main body, such as a corrugated shape in which uneven strips are formed in the width direction, or a striped steel plate having protrusions on the surface. Concrete propulsion pipe for the propulsion method.   3. The concrete propulsion pipe for a propulsion method according to claim 1, wherein the body winding material has a total surface area of 40% to 60% of the surface area of the propulsion pipe body.   4. The concrete propulsion pipe for propulsion method according to claim 3, wherein the interview ratio of the body winding material includes a steel material portion constituting an insertion portion and a socket portion constituting a joint of the propulsion tube. The propulsion pipe main body has an inner surface side concrete layer made of expanded concrete on the inner surface side, and an outer surface side concrete layer made of concrete having less expansibility compared to the inner surface side concrete layer on the outer surface side,
Between the inner surface side and the outer surface side concrete layer, an intermediate mortar layer made of a high-density mortar made impervious by adding a water repellent made of a drying shrinkage reducing agent,
Each of the concrete layers on the inner surface side and outer surface side has a reinforcing bar knurl structure having a reinforcing bar rod inside thereof,
The outer surface side concrete layer has a compressive strength of 14 days of age of 85 N / mm ² or more and a tensile strength of 8 N / mm ² or more by adding a high-strength admixture. Concrete propulsion pipe for the described propulsion method.