JP3429467B2 - Method of introducing prestress into egg-shaped concrete container 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 method for introducing prestress into an egg-shaped concrete container structure which is preferably used in a digestion tank for sewage.

[0002]

2. Description of the Related Art In recent years, the use of concrete egg-type digestion tanks, which are excellent in terms of shape and performance, have been increasingly adopted as digestion tanks for treating domestic sewage and sewage in urban areas. ing. This digestion tank is composed of a drooping bottom part buried in the ground, and an upper standing part where the remaining part is constructed on a ring base supported by foundation piles and stands on the ground.

The wall, which is the shell of the digestion tank in the upper standing portion, has a PC structure in which prestress is introduced into the wall in order to counter the hoop tension due to the internal pressure of the sewage. When prestressing is applied to this wall, a plurality of boat-shaped recesses are formed on the outer surface of the wall of the upper standing portion, and the PC in the parallel direction for one circumference is formed.
A structure in which a tension member is arranged within the thickness of the shell wall, and both ends of the PC tension member are intersected with each other at the recesses and tensioned at both ends of the PC tension member to fix the tension member to introduce circumferential prestress to the container wall. Has become. In this structure, the friction between the PC tension member and the insertion duct lowers the prestress introduction efficiency. Therefore, it is necessary to use a large amount of PC steel material, and since fixing is performed every one turn, a large number of expensive fixing tools are required. . Further, the construction cost has risen due to the need for a reinforcing steel material against the stress concentration in the fixing portion and the need to fill in the concave portion of the fixing portion.

On the other hand, since the bottom wall of the drooping bottom portion is buried in the ground and the outer surface of the wall is in contact with the ground, the fixing portion cannot be provided on the outer surface of the wall body like the upper standing portion. Therefore, many P
There is known a PC structure in which C steel materials are arranged in a helical shape and fixing portions are provided inside concrete and inside the wall.

Japanese Unexamined Patent Publication No. 62-271881 proposes a technique in which the pendant bottom portion is changed to a structure that can be easily constructed to form a reinforced concrete structure. That is, the egg-shaped wall part has a prestressed concrete structure, the foundation part has a reinforced concrete structure, and the skeleton in the middle part has a prestressed reinforced concrete structure. However, the reinforced concrete structure requires a huge amount of concrete, the wall thickness becomes large, and the stress transmission becomes complicated.

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, which enables the fixing tool to be installed with a minimum number, is disclosed. The technique is to reinforce the existing columnar structure. A curved panel is attached around the columnar structure via mortar, and a PC tension member is spirally inserted and wound in the curved panel plate. Lock one end of the tension material (cable) to the bottom or top of the curved panel,
This is a technique in which a jack is inserted into the slit between the curved panels from the locking point and the PC tension member exposed in the slit is sequentially tensioned toward the other end of the cable to introduce a tightening force to the structure. In the above technique, the number of expensive fixing tools used is minimized, and the tension can be reliably fixed. The above technique is a technique for tightening a structure serving as a core to reinforce the core structure.

[0007]

SUMMARY OF THE INVENTION The present invention basically follows the excellent technique that the egg-shaped structure is a prestressed concrete structure and uses a PC tension material amount and a fixing tool that are as small as possible. It has been improved to create a pre-stress introduction technology that can reduce costs without the need to reinforce individual fixing parts or fill in many recesses. That is, as a result of earnest research on a technique for introducing a prestress in the circumferential direction of the wall, referring to the technique disclosed in Japanese Patent Laid-Open No. 9-31918, the prestress in the circumferential direction that can be applied with a minimum number of fixing tools. The introduction method was developed. The present invention aims to provide such a technique.

[0008]

The present invention has been developed to solve the above problems. The technical means is to introduce prestress to the egg-shaped concrete container structure.
In doing so, the prestress introduction area should be
Divide into the bottom part and introduce tension with different PC tension materials
The upper erected part shall be pressed into the shell wall within the thickness of the shell wall.
A circumferential spiral PC that is continuous over the entire area
A tension material insertion duct is formed, and a PC tension material is formed in the middle.
The size of the jack that gives the jack tension
A recess having a jack reaction force support formed on the inner surface
A number of intermediate tension parts on the outer surface of the structure,
The droop is within the thickness of the shell wall over the entire prestressed area of the shell wall.
A PC tension member insertion duct that is continuous across and has a spiral shape in plan view
Form a jack, and in the middle, apply the jack tension to the PC tension material.
The jack is a recess that is large enough to operate
A large number of recesses with the reaction force support of the kick formed on the inner surface.
To form an intermediate tension section the structure inner surface, each of the duct long continuous PC tendon was inserted respectively, said it
Fix one end of respective of the PC tendon to the fixing unit, the it towards the fixing portion to the other end of the respective PC tendon
In the middle tension part , grip the PC tension material with multiple jacks
It is a method for introducing prestress in an egg-shaped concrete container structure, characterized in that the tension that is sequentially strained is repeated and finally fixed at the other end of the PC tension material.

The present invention is applied to an egg-shaped concrete container structure constructed by standing up, and basically, the following (a),
It is characterized by (b). (A) To form a PC tension member insertion duct in a circumferential (latitude) spiral shape that is continuous over the entire length of the prestressing area of the shell wall. (B) A long PC tension member is inserted into this duct, one end of this PC tension member is tightly attached to a terminal fixing body at one end of the prestress introduction region, and the PC is moved toward the other end of the prestress introduction region.
Tension the tendons sequentially and finally fix the PC tendons at the other end.

In order to achieve the above (b), an intermediate tension part is provided in the middle of the PC tension material insertion duct. In the present invention, the intermediate tension portion refers to a portion that grips the intermediate portion of the PC tension member with a jack or the like and partially applies tension to the PC tension member. For example, it is a concave portion provided on the wall surface, which has a size capable of exposing the PC tension member therein and operating the jack, and the reaction force supporting portion of the jack is formed on the inner surface.

The intermediate tension portion can be formed by one or a plurality of recessed grooves provided in the meridian direction of the wall surface of the eggshell, and if formed in this way, the intermediate tension portion having an appropriate shape and arrangement can be extremely easily formed. It can be formed and is preferable.

Further, the prestress introduction region is divided into an upper standing portion of the egg-shaped structure and a drooping bottom portion buried in the ground, and the tension force is introduced by at least two separate PC tension members. and the. In that case, in the first system, one or a plurality of recessed grooves are provided in the meridian direction of the wall outer surface of the upper standing portion, and at the same time, the side surface of the recessed groove is opened within the wall thickness to cover the entire length of the upper standing portion. A continuous long spiral PC tension member insertion duct is formed, a continuous PC tension member is inserted into this duct, one end of the PC tension member is tightly attached to the terminal fixing member, and the other end of the PC tension member is attached. Towards, the PC tension members exposed in the groove are sequentially gripped by a plurality of jacks inserted at different positions in the groove, and the tension is increased stepwise while alternately operating the jacks. Then, the system is finally settled at the other end of the PC tension material. In the second system, one or a plurality of recessed grooves are provided in the meridian direction of the wall inner surface of the drooping bottom part buried in the ground, and the recessed groove side surface is opened within the wall thickness to cover the entire wall length of the drooping bottom part. A continuous PC tension member insertion duct is formed, a long PC tension member is inserted into the duct, one end of the PC tension member is tightly attached to the terminal fixing member, and the other end of the PC tension member is attached. Toward the end, the PC tension material exposed in the groove is gripped by a plurality of jacks inserted in the groove having different positions, and the tension is alternately increased step by step. It will be a system that will finally settle at the end. With such a dual
Therefore, it becomes possible to introduce prestress to the entire structure with a minimum of four fixing members. The meridian here means a line in the vertical direction along the wall surface of the egg-shaped structure, and is perpendicular to the latitude line (the circular line of the wall surface cut horizontally).

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

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 14 is a partial cross-sectional side view of the egg-shaped concrete container structure 1 to which the present invention is applied. An underground pile 5 is struck on the ground 6, an upper standing portion 2 on the ground is erected on a ring base 3 formed thereon, and a drooping bottom portion 4 is formed on the underground side. This egg-shaped concrete structure 1 stores sewage 7 as a digestion tank, and the wall receives hoop tension. The precipitate has a shape suitable for being concentratedly collected in the central portion of the lower bottom and discharged.

As an example, an example in which the prestress introduction region is divided into an upper standing portion and a lower hanging bottom portion will be described. In the present description, illustrations of the meridional PC steel material and the reinforcing bars are omitted. FIG. 1 is a wiring diagram of the PC tension material 10 of the egg-shaped concrete container structure 1 (digestion tank). P
The PC strand 10 is used as the C-tension material, and there are two systems of an upper standing portion and a hanging bottom portion, and both are arranged in a spiral shape.

FIG. 2 is a sectional view taken along the line AA of FIG.
It is shown that the PC strand 10 disposed inside is exposed in the tension slit (concave groove) 20 that opens to the outer surface of the wall body. In this example, the concave groove 20 is shown as four concave grooves along the meridian from the top end to the lower end of the upper standing portion, but the present invention is not limited to this, and the number, arrangement, length, etc. are not limited thereto. It can be determined according to the design. Depending on the case, the concave portions may be dispersed separately.

FIG. 3 is an explanatory view of the prestressing step of the wall of the upper standing portion. One end of the PC strand 10 is tightly attached with the terminal fixing body 12, the first jack 31 is attached to the PC strand 10 of the portion exposed in the concave groove 20, and the first jack 31 is operated to fix. Tension is introduced into the PC strand 10 between the body 12 and the jack 31. Next, the second jack 32 is attached to the PC strand 10 in the groove 20 where the PC strand 10 is exposed next, and the second jack 32 is operated while maintaining the tension of the first jack 31. The tension is introduced into the PC strand 10 between the jacks 31, 32. afterwards,
While maintaining the tension of the second jack 32, the tension of the first jack 31 is released and the PC strand 10 in the next exposed groove 20 is attached to the third jack 33.
Is installed and activated to introduce tension in the PC strand 10 between the jacks 32, 33. Third jack 33
The tension of the second jack 32 is released while maintaining the tension of the second jack 32. The third jack 33 may be used by moving the first jack 31.

Next, in the same manner, the fourth jack 34 is attached to the PC strand exposed in the groove 20, and the same operation as above is repeated to sequentially introduce prestress to the other end of the PC strand 10. .

In the description of FIG. 3, the concave groove 20 into which the tensioning jack is inserted is at the same position, but in reality, the concave groove is displaced by 1/4 or 1/2. The position may be determined so that the prestress introduction can be performed most effectively while considering the friction between the insertion duct and the PC strand. Further, although FIG. 3 is a diagram in which the prestress is introduced from the bottom to the top, the same applies when the prestress is introduced from the top to the bottom. In addition, when the number of turns becomes large and the length of the PC strand supplied from the manufacturer is insufficient, the other end is fixed at an intermediate position of the spiral and connected to another PC strand, or another position is provided at that position. P
It is also possible to fix one end of the C strand and start the same tension as above.

FIG. 4 is a sectional view of the wall body showing a tension jack 31 mounted in the groove 20 of the wall body 11. The tension jack 31 can be inserted into the groove 20 from the outside of the groove and can be mounted so as to cover the PC strand 10 exposed in the groove 20 from the side so that it can be easily attached and detached and moved. ing.

FIG. 5 is a front view showing the tension slit (concave groove 20) and the tension jack 31 mounted in the groove 20 in the BB arrow view of FIG. The PC strand 10 is inserted into the duct formed by the sheath 13 in the wall body 11. The PC strand 10 is exposed in the concave groove 20, and is gripped and tensioned by the wedge of the tension jack 31.
After the prestressing of the wall body 11 is introduced into the groove 20, the inside of the sheath 13 is grouted, and at the same time, the residual filling concrete is filled.

FIG. 6 is a detailed view of the hanging bottom portion 4 and shows a state in which the PC strand 10 of a different system from the upper standing portion 2 is arranged. FIG. 7 is a view taken in the direction of arrows CC in FIG. 6, in which tension slits composed of concave grooves 20 are radially formed on the inner surface of the wall of the hanging bottom portion 4 from the vicinity of the center of the lower bottom portion toward the peripheral edge of the ring base. The recessed groove 20 forms an intermediate tensioned portion for gripping and tensioning the intermediate portion of the PC strand 10 with a jack. In the example of FIG. 7, four concave grooves 20 are formed. The PC strand 10 is provided at a position near the center of the drooping bottom portion 4.
One end of the PC strand 10 is fixed to the fixing body 12, and the PC strand 10 is arranged in a spiral shape in a side view (spiral shape in a plan view) from here. The other end of the PC strand 10 is
It is fixed to the fixing portion 14 at the upper end of the groove 20.

FIG. 8 is an explanatory view of the introduction of prestress in the drooping bottom portion 4, and is an enlarged plan view of the central portion of FIG. 7. One end of the PC strand 10 is tightly attached with the terminal fixing body 12, and the first jack 31 is attached to the PC strand 10 exposed in the recessed portion 20 located at a position separated by a half circumference from this, and the first jack 31 is operated. Between the fixing body 12 and the jack 31
A tension force is introduced into the C strand 10, and then the second jack 32 is attached to the PC strand 10 exposed from the first jack 31 in the groove 20 at the semicircular position,
The second jack 32 is operated while maintaining the tension of the first jack 31 to introduce the tension between the jacks 31 and 32. After that, the tension of the first jack 31 is released while the tension of the second jack 32 is maintained. Next, the third jack 33 is inserted at the jack mounting position in the front concave groove 20, and the third jack 33 is mounted on the PC strand 10 exposed in the concave groove 20,
The third jack 33 is activated to introduce tension between the jacks 32, 33. The third jack 33 may be a transfer of the first jack 31. Next, while maintaining the tension of the third jack 33, the fourth jack 34
Is inserted into the concave groove to tension the PC strand 10 between the jacks 33 and 34, and then the third jack 33 is released. By repeating this alternately to the other end of the PC strand, the prestress is surely introduced into the PC strand 10.

In this case, the operating position of the jack may be appropriately changed and determined in consideration of the friction coefficient due to the curvature of the PC strand. Also, a PC that is supplied with a large number of turns
When the length of the strand is insufficient, the other end may be fixed at a midway position of the spiral and the PC strands may be connected to each other or one end of the PC strand may be started from that position.

FIG. 9 is a side view of the tension jack 33 mounted in the recessed groove 20 in the view of the arrow DD in FIG. FIG. 10 is a front view of the groove 20 and the tension jack 33 mounted in the groove 20 as seen from the arrow E-E of FIG. 8. The PC strand 10 is inserted into the duct formed by the sheath 13 in the wall 11 of the drooping bottom portion 4, and is exposed in the concave groove 20,
Tensioned by the wedge of the tension jack and getting tense. After the prestress is introduced into the drooping bottom portion 4, the inside of the sheath 13 is grouted, and at the same time, the groove 20 is filled with the trace-filling concrete.

FIG. 11 shows an example of a tension jack 31 of the present invention which is most suitable for introducing prestress. It has a machine length as short as possible that can be mounted in the intermediate tension portion (concave groove 20).
Wedge structure 3 so that the middle of the PC strand 10 can be grasped
The two cylinders 35 and the ram 36 work together to apply tension to the PC strand 10. 11 is a plan view, FIG.
2 and 13 are FF and GG arrow views of FIG. 11, respectively.

In this example, the egg-shaped concrete container structure has been described, but the present invention is also applicable to a vertical hanging portion of an abacus ball-shaped container, which is a similar technique. Further, although the example in which the intermediate tension portion is the four concave grooves has been described, the intermediate tension portion is not limited to this. For example, in consideration of the friction between the PC strand and the duct, the effectiveness of introducing the prestress, and the like, it is possible to determine the appropriate shape, position, arrangement, and arrangement quantity of the intermediate tension portion by design.

[0028]

According to the method of the present invention, the circumferential prestress can be effectively introduced into the egg-shaped concrete container structure with the minimum fixing portion. Further, it becomes possible to easily apply a predetermined tension force even if the amount of PC tension material and the fixing tool, which has been a factor of the soaring construction cost, is reduced.
Further, it is not necessary to reinforce the fixing portion of the fixing steel or to fill the area, and the number of construction steps can be reduced and the construction period can be shortened.

[Brief description of drawings]

FIG. 1 is a partial sectional side view of an embodiment.

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

FIG. 3 is an explanatory diagram of a tensioning step.

FIG. 4 is a sectional view of an intermediate tension portion.

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

FIG. 6 is a partial cross-sectional side view of a hanging bottom portion.

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

FIG. 8 is an explanatory view of tension in a partially enlarged view of FIG.

9 is a sectional view taken along the line DD of FIG.

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

FIG. 11 is an explanatory diagram of a jack.

FIG. 12 is an explanatory diagram of a jack.

FIG. 13 is an explanatory diagram of a jack.

FIG. 14 is a partial cross-sectional side view of an egg-shaped concrete container structure to which the present invention is applied.

[Explanation of symbols]

1 egg-shaped concrete container structure 2 Upper part 3 ring base 4 Drooping bottom 5 piles 6 ground 7 dirty water 10 PC tension material (PC strand) 11 wall 12 Terminal fixing body 13 sheath 14 Fixing section 20 groove (slit for tension) 31, 32, 33, 34 jacks 35 cylinders 36 Ram 37 Wedge structure

Continuation of the front page (56) Reference JP-A-9-31918 (JP, A) JP-A-50-58841 (JP, A) JP-A-62-174466 (JP, A) JP-A-62-1980 (JP , A) Japanese Unexamined Patent Publication No. 6-322889 (JP, A) Actual Development Sho 60-117903 (JP, U) Japanese Patent Publication No. 42-9864 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) E04H 7/20 E04G 21/12 B65D 88/04 B65D 90/02

Claims (2)

(57) [Claims] 1. A presto for an egg-shaped concrete container structure.
When introducing the loess, the prestress introduction area
It is divided into an upright part and a drooping bottom part, and separate PC tension materials
It is assumed that the tension is introduced, and the upper standing part is the entire prestressing area of the shell wall within the thickness of the shell wall.
Circumferential spiral PC tension material insertion duck that is continuous over the area
To the PC, and on the way, jack tension to the PC tension material.
Is a recess that is large enough to operate the jack
A large number of recesses with the reaction force support of the jack formed on the inner surface
An intermediate tension part of the shell is formed on the outer surface of the structure, and the drooping bottom part is within the shell wall thickness and the entire prestress introduction area of the shell wall.
PC tension material insertion duck that is continuous in plan view and spiral
To the PC, and on the way, jack tension to the PC tension material.
Is a recess that is large enough to operate the jack
A large number of recesses with the reaction force support of the jack formed on the inner surface
Of the intermediate tension section is formed in the structure interior surface, the PC tendon continuous elongated in respective ducts it
Insert each through, fix one end of each of the PC tension members to the fixing portion, and from the fixing portion toward the other end of each of the PC tension members, insert a plurality of PC tension members at the intermediate tension portions.
Repeatedly tense by grasping with the jack of
A prestressing method for an egg-shaped concrete container structure, characterized in that it is finally fixed at the other end of the tension material. 2. The intermediate tension part is in the meridian direction of the eggshell wall surface.
The method for introducing prestress in an egg-shaped concrete container structure according to claim 1, characterized by comprising one or a plurality of recessed grooves provided .