JPH08260448A - Pressure-resistant cylindrical pipe and laying method thereof - Google Patents

Abstract

PURPOSE: To provide a pressure-resistant cylindrical pipe being used for a conduit or a water-conveyance tunnel or the like receiving high internal pressure and having a comparatively large bore. CONSTITUTION: A double steel shell 2 is formed in a segment shaped of an external steel shell 3, an internal steel shell 4 and tie rods 5, and joining sections 6 are welded and joined, thus forming a cylindrical pipe. The inside of the steel shell 2 is filled with concrete 7, thus forming a pipe wall having composite structure. A sheath 9 is wound spirally on an outer circumference, and a PC tension member 8 is inserted into the sheath 9, and the tension member 8 is stretched and hoop compressive force is given.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-resistant cylindrical pipe having a relatively large diameter, which is used for a conduit pipe for receiving a high internal pressure such as a connecting conduit pipe for a reservoir having a height difference or a water main pipe.

[0002]

2. Description of the Related Art A pipe that receives a high internal pressure, such as a pumping pipe of a pumped-storage hydroelectric power plant that effectively uses surplus power at night, needs to receive a high internal pressure and secure a large flow rate. Pressure tube is required. In such pressure-resistant cylindrical pipes such as water mains that receive high internal pressure and connecting water conduits that have a large difference in height, the circumferential tension (hoop tension) acting on the pipe wall increases as the pipe diameter increases, making it thicker. There was a problem that needed.

[0003] Conventionally, in a waterway tunnel in a mountainous area, it is usual to form a water passage by concrete lining on the inside of the excavated tunnel by casting in situ, which requires long-term construction, economical efficiency and construction speed. There is a room for improvement. On the other hand, from the viewpoint of improving workability and saving labor, when constructing a pipeline by laying a ready-made pipe body in the space excavated from the ground or above the ground, backfilling or backfilling into the outer peripheral space of the pipe It is not easy to carry out the work so that the external pressure such as the earth pressure and earth pressure due to the soil becomes uniform, and the deformation of the pipe body due to uneven pressure, cracks in the pipe wall, etc. may result in water leakage or breakage.

FIG. 6 shows the condition of the cylindrical tube 1 installed in the tunnel. Generally, it is difficult to tightly fill the backing material 14 with a tight gap, so that a void 15 is formed on the outer surface of the cylindrical tube 1.
When the internal pressure 13 is applied to the cylindrical tube 1, an unbalanced load is generated. Further, FIG. 7 shows that the cylindrical tube 1 installed in the excavated ground receives a non-uniform bias pressure 16 and may be deformed when the internal pressure 13 is applied.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pressure-resistant cylindrical tube suitable for such a case, which is suitable as a conduit having a relatively large diameter for receiving internal pressure, and a method for laying the same. And The problems of the present invention are as follows. (1) It should be as thin as possible and have a rational structure. (2) The size and weight that can be transported as a ready-made member. (3) Large-diameter products should be segmented to enable local assembly. (4) Withstand internal pressure as well as external bias.

[0006]

Means for Solving the Problems The present invention is to solve the above-mentioned problems, and a cylindrical tube wall having a composite structure of steel and concrete in which concrete is filled between an outer steel shell and an inner steel shell, and the outer wall. A pressure-resistant cylindrical tube comprising a PC tension material arranged in a hoop shape on the outer peripheral surface of a steel shell or the inner wall surface of an outer steel shell. This double steel shell is preferably a connected body of a plurality of arc-shaped segments.

The present invention achieves the above object by making the pipe wall a composite pipe body of steel plate and concrete, and leaving a uniform compressive stress in the pipe wall cross section. The pressure-resistant cylindrical pipe laying method of the present invention is to manufacture divided arc-shaped double steel shell segments and assemble them by welding in a cylindrical shape at the site, and place between the outer steel shell and the inner steel shell of the double steel shell. After filling the concrete and hardening the concrete, wrap the PC tension material around the double steel shell,
The method is performed by introducing a hoop tension force to form a synthetic structure cylindrical body piece, sequentially connecting the cylindrical body pieces by welding, and filling the outer space thereof with concrete.

[0008]

The following effects are brought about by the present invention. (A) Since the PC tension material resists the hoop tension, the pressure resistance is significantly improved, and the double steel shell can be formed of a relatively thin steel plate. (B) Since the inside of the steel shell is filled with concrete to form a composite structure, the yield strength is increased.

The tubular body of the present invention is made of reinforced concrete (RC).
However, in order to withstand the internal pressure, a large wall thickness is required, and on-site work such as processing and assembly of reinforcing bars and formwork, formwork support work, etc. becomes complicated. There is also a method of manufacturing a precast concrete segment at a factory, bringing it into the field and assembling it, and inserting it by inserting PC tension material and introducing prestress, but it is possible to use a precast concrete segment with a high precision joint surface. Must be manufactured.

In the pipe body of the present invention, arc-shaped double steel shell segments divided in consideration of portability are manufactured in a factory or the like, and after being carried into the field, they are assembled into a cylindrical shape and the steel plates on the joint surface are welded together,
The concrete is filled in the double steel shell, and after the concrete is hardened, the PC tension material is inserted into the sheath attached to the outer circumference of the steel shell or the sheathed wire is wound to spirally wrap the PC tension material. A prestress is introduced into the to fix it and to resist the hoop tension generated by the internal pressure of the cylindrical tube to form a cylindrical piece having a synthetic structure. This cylindrical piece is temporarily installed at the laying position, the joining end faces are aligned so as to connect pieces formed in the same manner in the longitudinal direction, and the steel plate joints in the butt circumferential direction are welded. This joint steel plate is mutually extended in the axial direction,
After welding, the space formed by the extension may be filled with concrete.

The advantage of the cylindrical pipe of the present invention having a composite structure of steel shell and concrete is that it has a large bending rigidity because it acts as an integral structure against the biased pressure due to voids or the like generated on the outer periphery of the pipe after it is buried underground. Becomes By introducing a pre-stress against the hoop tension to the outer periphery by the PC tension material, a stress-clear structure is obtained as compared with the concrete pipe having the RC structure. The PC tension member sheath can be easily arranged by providing a guide pipeline on the outer circumference of the outer steel plate or the inner wall of the outer steel plate.

It is also possible to lay the joined cylindrical pipe pieces one by one by a known propulsion method, and sequentially add the cylindrical pipe pieces to the rear of the pieces to propel them to a predetermined pipe length. According to the above laying method of the present invention, by carrying in and assembling the relatively lightweight steel shell segment,
Since no concrete formwork is required and no processing or assembly of rebar is required, the effect of saving labor and shortening the construction period is great.

The structure of the pressure resistant cylindrical pipe of the present invention can be used for a bridge pier of a bridge. For a bridge pier having a large load bearing capacity, it is preferable to use a solid structure in which the hollow portion in the cylindrical pipe of the structure of the present invention is filled with concrete.

[0014]

1 is a perspective view of a cylindrical tube 1 according to an embodiment of the present invention. The double steel shell 2 forms the cylindrical tube 1 by welding and joining the segments formed by the outer steel shell 3, the inner steel shell 4, and the connecting material 5 at the joint portion 6. The double steel shell 2 is filled with concrete 7 to form a tube wall having a composite structure of steel shell and concrete. A sheath 9 is provided around the outer steel shell 3.
Is wound in a spiral shape, and a PC tension member is inserted thereinto to tension the PC tension member to give a hoop compression force. FIG. 2 shows a vertical cross-section of a cylindrical pipe 1. The outer steel shell 3 and the inner steel shell 4 form a double steel shell 2 by a circumferential connecting material 5, and the pipe longitudinal direction is an inner circumference welding 10 and an outer circumference welding. Connect by 11. FIG.
Is a partially enlarged view of this connecting portion. As shown in FIG.
The outer steel shell 3 and the inner steel shell 4 are respectively extended in the pipe axial direction so that the welding 10 and 11 can be easily performed, and the concrete 7 is placed in the space formed by the extended steel shell. It can be filled from a filling hole or the like. FIG. 4 shows a cross section of the cylindrical pipe 1. The arc-shaped segments formed by the outer steel shell 3 and the inner steel shell 4 are connected by an inner seam weld 17 and an outer seam weld 18. A window 19 is provided in the connecting material 5, and concrete communicates through the window 19, so that concrete pouring is easy. In FIG. 5, the tension member 8 is provided on the inner surface side of the outer steel shell 3, that is, in the concrete 7. The PC tension member 8 is inserted into a sheath 9 embedded in concrete. The end of the sheath 9 is exposed on the inner surface of the tube, and the PC is
Fixing parts at both ends of the tension material are provided. PC in the embodiment of FIG.
Since the tension member 8 is built in and no irregularities are formed on the outer peripheral surface of the outer steel shell 3, it does not become an obstacle during propulsion, which is more rational.

A design example of the pressure resistant cylindrical tube of the present invention will be described.
The circumferential tension T of the pipe line having an inner diameter D = 8.0 m on which the internal pressure p = 120 tf / m ² (12 kgf / cm ² ) acts is T = p (D / 2) = 480 tf / m (pipe length). Thickness of inner and outer steel plates forming the steel shell t ₁ = t ₂ =
0.022 m (22 mm) and filled concrete thickness t
Calculating as a composite structure of steel shell concrete with c = 0.25 m (25 cm), the tensile stress σ _sc generated in the steel shell concrete cylindrical wall cross section is σ _sc = circumferential tension T / {concrete thickness tc + n (steel plate t ₁ + t ₂ )} = 480 / (0.25 + 6 × 0.044) = 934tf / m ² = 93.4 kgf / cm ² where n is the Young's modulus ratio of the steel material / concrete, Young's modulus of the steel material Es = 2100 × 10 ⁴ tf / m ² ,
Young's modulus of concrete Ec = 350 × 10 ⁴ tf
From / m ² , n = 2100/350 = 6.

Next, as reinforcing PC tension members provided on the outer periphery, PC tension members φ21.8 (tensile strength = Tp = 34 tons) are used per 14 m of pipe length, and the peripheral stress (prestress) applied is σ _p = (Tp × N) / {tc + n (t ₁ + t ₂ )} = (34 × 14) / {0.25 + 6 × (0.022 + 0.022)} = 926 tf / m ² = 92.6 kgf / cm ² Becomes Therefore, the synthetic stress Σσ is Σσ = σ _sc + σ _p = −93.4 + 92.6 = −0.8 kgf / cm ² , and the hoop tension generated by the internal pressure can be almost covered only by the prestress of the PC tension material. If the cross section of the steel shell is taken into consideration, a tube with an extremely high safety factor can be obtained.

In this example, the case of a relatively large diameter is taken as an example.
Depending on the pipe body corresponding to the required bore and internal pressure, the thickness of the steel plate,
It is possible to design the concrete wall with the optimum thickness. Next, a method of laying the pressure-resistant cylindrical tube of the present invention when used in a pressure tunnel will be described. A steel plate segment having a double steel shell structure is assembled into a cylindrical shape, and the inside thereof is filled with concrete to form an integrally structured cylindrical piece. PC for prestress placed on the outer diameter of the cylindrical piece after that
Prestress with tension material. In this state, it is carried into a tunnel that has already been excavated, joined to an existing cylinder, and extruded. The joining between the cylindrical pieces is by welding steel plates. The outer side and the inner side are welded in this order, and the space formed by the welding is grouted and extruded. The length of the cylindrical piece in the longitudinal direction is determined in consideration of handling during assembly. When the inner diameter D is 8 m, the circumference length is πD = 25.1
m, and the length of the cylindrical piece is 2 m, the weight W is 2
5.1 x 0.044 x 2.0 x 7.85 = 17.34 tons.

In this embodiment, since it is not necessary to attach and detach the formwork or assemble the reinforcing bars, it is possible to carry out the construction in a short period of time.

[0019]

EFFECTS OF THE INVENTION Since the pressure-resistant cylindrical tube of the present invention is constructed as described above, it is tough against internal pressure and external bias pressure, has excellent characteristics, and can be transported according to size and weight. Cylindrical pipes can be installed on-site by using the divided steel shell segments as forms and structural materials, which eliminates the need for processing and assembling forms, rebars, etc., which contributes to labor saving, shortening the construction period, and improving economic efficiency.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment.

FIG. 2 is a vertical sectional view of an example.

FIG. 3 is a vertical cross-sectional view of a joint portion of a steel shell of an example.

FIG. 4 is a cross-sectional view of the joint portion of the steel shell of the example.

FIG. 5 is a vertical sectional view of an example.

FIG. 6 is a cross-sectional view of the tunnel.

FIG. 7 is a cross-sectional view of an underground buried pipeline.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cylindrical tube 2 Steel shell 3 Outer steel shell 4 Inner steel shell 5 Connecting material 6 Joining portion 7 Concrete 8 PC tension material 9 Sheath 10 Inner circumference welding 11 Outer circumference welding 13 Inner pressure 14 Backfill material 15 Void 16 Unbalanced pressure 17 Inner seam welding 18 Outside seam welding 19 Window

Claims (3)

[Claims] 1. A cylindrical pipe wall having a composite structure of steel and concrete in which concrete is filled between an outer steel shell and an inner steel shell, and a hoop-shaped arrangement on the outer peripheral surface of the outer steel shell or the inner wall surface of the outer steel shell. A pressure-resistant cylindrical tube, characterized in that it comprises a PC tension material that is installed. 2. The pressure-resistant cylindrical pipe according to claim 1, wherein the double steel shell is a connection body of a plurality of arc-shaped segments. 3. A segmented arcuate double steel shell segment is manufactured and assembled on site by welding in a cylindrical shape, concrete is filled between the outer steel shell and the inner steel shell of the double steel shell, and concrete is formed. After hardening, a PC tension material is wound around the outer periphery of the double steel shell, a hoop tension force is introduced to form a synthetic structure cylindrical body piece, the cylindrical body pieces are sequentially welded and connected, and the outer space thereof is filled with concrete. A method for laying a pressure-resistant cylindrical pipe, characterized by: