JP3375585B2 - Method of introducing prestress into cylindrical body of cylindrical concrete structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circumferential prestressing method for a cylindrical container structure such as a tank or silo, or a cylindrical concrete structure such as a chimney or a pressure pipe.

[0002]

2. Description of the Related Art Conventionally, a cylindrical container structure such as a tank 40 for storing a fluid as illustrated in FIG. 8, a surge tank of a pumped storage power plant, a cylindrical concrete structure such as a cement silo, etc., ensures a tightness. In addition, a container structure having a PC structure in which a prestress is introduced into the wall is used to counter the hoop tension due to the internal pressure of the stored material.
When introducing circumferential prestress into the wall body, as shown in an example in FIG. 9, a plurality of (in this example, four places) the outer surface of the wall body 41.
Pillars 45 of the
The tendon 12 is generally fixed. FIG. 9 is a perspective view of the cylindrical body, and independent semicircular circumferential PC tension members are provided over the entire length of the prestress introduction region. FIG. 10 shows a cross section taken along the line DD of FIG. PC
The tension members 12 are arranged in a large number of stages. In each stage, one PC tension member 12 is used for each semicircle, and the pillars 45 are crossed at positions different by 180 degrees to make tension at both ends of the PC tension members 12. And fix it. In the next stage, the fixing position is set to a position different by 90 degrees, and similarly, two PC tension members 12 are crossed by a pilaster 45 every 180 degrees and are tensioned and fixed at both ends of the PC tension member 12. The circumferential prestress is introduced into the wall of the cylindrical container by alternately repeating the above in each axial step.
In such a conventional technique, since the introduction efficiency of the prestress is reduced due to the friction between the PC tension member 12 and the insertion duct, a large amount of the PC tension member 12 is required.
Since stress concentrates on the ground, reinforcement is required, and a large number of expensive fixing devices are required, which causes a rise in construction costs and has been a problem.

On the other hand, the applicant of the present invention has filed Japanese Patent Application Laid-Open No. 9-31918.
In the publication, a tension fixing method for a PC tension member that can be fixed using a minimum number of fixing tools is disclosed. The technique is a technique for reinforcing a columnar structure, and mortar is provided around the columnar structure. Attach a curved panel with a slit for tension, insert a PC tension material in a spiral shape inside the curved panel plate and wind it, and lock one end of the tension material to the lower part or the upper part of the curved panel and tighten from the locking point. To the other end of the material, insert a jack into the tensioning slit between the curved panels to tension the PC tensioning material exposed in the slit, and sequentially move the jack toward the other end of the tensioning material to tension the other end. It is a technology that establishes This technique is a technique for reinforcing the columnar structure by introducing a tightening force to the outer periphery of the columnar structure serving as a core.

[0004]

SUMMARY OF THE INVENTION The present invention is a technique for introducing a prestress in the circumferential direction into a cylindrical structure, and a method that can be constructed at a low cost by using a minimum number of expensive fixing devices. The purpose is to provide. In this case, the technique disclosed in Japanese Unexamined Patent Publication No. 9-31918 described above can minimize the number of fixing tools to be used and can reliably fix the tension force. The above-mentioned technology is to tighten and reinforce the structure to be the core body, but the present invention is quite different from this, which introduces prestress in the circumferential direction of the wall of the cylindrical structure, and This is a technically excellent prestress introduction technology for cylindrical structures that can reduce costs such as improvement of introduction efficiency, elimination of stress concentration, and reduction of expensive fixing tools.

[0005]

According to the present invention, a spiral PC tension member insertion duct is formed in the wall thickness of a cylindrical body of a cylindrical concrete structure, and the spiral PC tension member insertion duct is formed in a groove provided in the middle of the duct.
The PC tension material insertion duct opens, and the PC tension material is in this groove.
A large number of intermediate tension parts exposed inside are provided, and a continuous PC tension member is inserted into the duct over the entire length of the cylinder and one end is locked. Is pretensioned at the other end and is finally fixed at the other end.

According to the present invention, a spiral which is continuous over the entire length of the prestress introduction region is provided on the cylinder wall of the prestress introduction region which opposes the hoop tension acting on the cylinder of the cylindrical concrete structure such as a tank for storing the fluid. This is a technique for efficiently introducing the pre-stress in the circumferential direction to the minimum fixing section by using a single PC tension material. The spiral PC tension member insertion duct has a large number of intermediate tension portions in the middle thereof. In the middle tension section, hold the PC tension material with a jack and pull it
The PC tension member is exposed so that the tension force can be introduced into the C tension member, and includes a support portion that supports the reaction force of the jack. For example, a recess or a hole provided in a concrete wall. As the intermediate tension part, a concave groove parallel to the cylinder axis is provided on the inner surface or the outer surface of the cylindrical wall, and the PC tension material insertion duct is opened in this groove so that the PC tension material is exposed in this groove. It can be easily formed by leaving it.

Further, a plurality of the cylindrical concrete structures are erected so as to be circumscribed to each other, and a spiral PC tension material insertion duct is communicated with a duct in an adjacent cylinder wall at a circumscribing portion of each cylinder. If the PC tension member is inserted through the duct of the cylindrical body in order, prestress can be simultaneously introduced into a plurality of cylindrical concrete structures, which is preferable. This cylindrical concrete structure is composed of a plurality of circumscribing cylinders, and the PC tensioning material insertion duct is arranged to be continuous from one cylinder to the other cylinder across the circumscribing portion. For example, when two cylindrical concrete structures are connected to each other, the PC tension member insertion hole is formed in a shape which is formed when the figure 8 is made into a plane and overlapped with one stroke. You may connect three or more cylindrical structures.

Further, in order to preferably carry out the present invention, a continuous spiral of PC tension material can be obtained by using the portable pinch roller for inserting PC strand disclosed in Japanese Patent Application Laid-Open No. 9-37953 proposed by the present applicant. It is easy to insert into the duct.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view showing an example of a cylindrical body portion of the container structure of the embodiment. It is shown that the PC strands 12 that are continuous over the entire length of the tubular body are arranged in a PC tension material insertion hole (sheath) 11 formed in a spiral shape. The PC tension material insertion holes 11 are exposed in concave grooves 21 provided at four locations in the circumferential direction in parallel with the cylinder axis. This exposed part is the intermediate tension part. 2 is a sectional view taken along the line AA of FIG.
It shows that it is exposed inside.

FIG. 3 is an explanatory diagram of the introduction of prestress.
In FIG. 3, for ease of explanation, the tension jacks 31 to 31.
Although the concave groove 21 in which 4 is inserted is drawn so as to be in the same groove, it is in the concave groove at a position shifted by 1/4 circumference or 1/2 circumference in practice. This position should be determined as the most effective position for introducing prestress, taking into consideration the friction between the insertion duct and the PC strand.

One end of the PC strand 12 is attached to the terminal fixing member 1
The first jack 31 is mounted on the PC strand 12 that is tightly locked at 3, and is exposed in the recess 21 at a position separated by a half circumference, and the first jack 31 is operated to introduce a tension force. Next, the second jack 32 is attached to the PC strand 12 exposed in the recess 21 located at a position further distant from the first jack 31 by the second jack 32 while the tension of the first jack 31 is maintained. The jack 32 is actuated to introduce tension. After that, the tension of the first jack 31 is released while keeping the tension of the second jack 32, and the first jack 31 is moved to the next jack mounting position. The number of jacks after moving is 33. Jack 33
The second jack 32 is released and moved to the position of the jack 34 with the tension force introduced and held. In this way, the movement and the reattachment are alternately repeated to the other end of the PC strand to introduce the prestress. The arrow 35 indicates the introduction direction of prestress, but the same applies to introduction from the top to the bottom.

Further, the number of laps becomes large, and the supplied P
When the length of the C strand is insufficient, the other end may be fixed at an intermediate position of the spiral and the PC strands may be connected to each other, or one end of the PC strand may be further started from that position.

FIG. 4 is a front view of the tension jack 31 mounted in the tension slit of the wall body. The tension jack 31 is provided with a groove 2 on the PC strand 12 exposed in the groove 21.
Since it is mounted so as to be covered from the outside of 1, it is easy to attach and detach.

FIG. 5 is a side view showing the groove 21 and the tension jack 31 mounted in the groove 21, which is a view taken along the line BB of FIG. The PC strand 12 is inserted into the duct formed by the sheath 11 in the wall body.
No. 2 is exposed in the concave groove 21, and is gripped by the wedge of the tension jack 31 to be tensioned. The reaction force of the tension jack 31 is supported on the inner surface of the groove 21. After the prestressing of the wall body is introduced, the inside of the sheath 11 is grouted, and the groove 21 is filled with the residual filling concrete.

FIG. 6 shows another embodiment in which two cylindrical concrete structures 10a and 10b are circumscribed to form an integral structure, and a PC strand inserted from one cylindrical concrete structure 10a. 12 is continuously inserted in the other cylindrical concrete structure 10b. 6 is a perspective view, and FIG. 7 is a view taken along the line CC of FIG. The PC tension member 12 is continuously inserted into the two cylindrical concrete structures 10a and 10b so that the Arabic numeral 8 is written as one stroke.

FIG. 11 is a plan view showing an example of the tension jack 31 most suitable for introducing prestress of the present invention. The jack 31 has a short machine length that can be mounted in the concave groove, and the two cylinders 35 and the ram 36 interlock with the wedge 37 so that the middle of the PC strand 12 can be grasped.
Give tension to. 12 and 13 are a EE arrow view and a FF arrow view of FIG. 11, respectively.

In the above embodiment, four concave grooves 21 are provided on the outer wall surface of the cylindrical concrete structure. However, the present invention is not limited to this. effective. Also, the number and arrangement of the concave grooves 21 can be appropriately designed, for example, in consideration of the friction between the PC strand of the cylindrical concrete structure and the duct, and in consideration of the effectiveness of prestress introduction.

[0018]

According to the method of the present invention, a spiral PC tension member is inserted into the wall thickness of a cylindrical concrete structure over the entire length of the prestress introduction region, and the PC tension member is jacked along the way. Since it is gripped with and the tension is increased in order, it is not necessary to provide a fixing portion such as a pilaster, and the entire length of the PC tension material wound in a spiral shape can be tensioned.
Only one fixed body is required. Therefore, it is possible to reduce the number of PC tension members and fixing tools, which have conventionally been one cause of soaring construction costs, and it is possible to easily apply a predetermined tension force without the need to reinforce the fixing portion. And the effect is enormous.

Further, when the cylindrical concrete structure is composed of a plurality of circumscribing cylinders, the PC tension member insertion duct may be continuously arranged from one cylinder to the other cylinder to make tension. Moreover, the effect of reducing the fixing body is great.

[Brief description of drawings]

FIG. 1 is a perspective view of a cylindrical structure of an example.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an explanatory diagram showing steps of the method of the present invention.

FIG. 4 is a front view of the jack in the intermediate tension section.

5 is a view taken along the line BB of FIG.

FIG. 6 is a perspective view of another embodiment.

7 is a cross-sectional view taken along the line CC of FIG.

FIG. 8 is a partial cross-sectional side view showing an example of a cylindrical container structure.

FIG. 9 is a perspective view illustrating a conventional technique.

10 is a cross-sectional view taken along the line DD of FIG.

FIG. 11 is a plan view of the jack used in the present invention.

FIG. 12 is a view on arrow EE in FIG. 11.

13 is a view on arrow FF in FIG. 11. FIG.

[Explanation of symbols]

10a, 10b Cylindrical concrete structure 11 Sheath (tension material insertion hole) 12 PC strand (PC tension material) 13 Terminal fixing body 21 groove 31, 32, 33, 34 Tension jack 35 arrow 35 cylinders 36 Ram 37 Wedge

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Claims (3)

(57) [Claims] 1. A spiral PC tension member insertion duct is formed in a wall thickness of a cylindrical body of a cylindrical concrete structure , and the PC tension member insertion duct is opened in a groove provided in the duct.
The PC tension member is provided with a large number of intermediate tension portions exposed in the groove, and the PC tension member is continuous in the duct over the entire length of the cylinder.
A cylindrical body of a cylindrical concrete structure, characterized in that a tension material is inserted and one end is locked, the PC tension material is sequentially tensioned at the intermediate tension portion to tension the entire length, and finally fixed at the other end. Method of introducing prestress in the department. 2. The cylindrical concrete according to claim 1, wherein the intermediate tension portion comprises one or a plurality of recessed grooves provided in a cylindrical wall surface of the cylindrical concrete structure in parallel with the cylindrical axis. A method for introducing prestress in the cylindrical portion of a structure. 3. A plurality of the cylindrical concrete structures are erected so as to be circumscribed to each other, and a spiral PC tension material insertion duct is communicated with a duct in an adjacent cylinder wall at an circumscribing portion of each cylinder. 3. The prestressing method for introducing a prestress into a tubular part of a cylindrical concrete structure according to claim 1, wherein the PC tension member is inserted through the duct of the tubular body in order.