JP3910131B2 - PC tank dome ring repair method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dome ring repair in a wrapping type prestressed concrete tank (hereinafter referred to as a PC tank) in which a tension member such as a PC steel wire is wound around the outer periphery of a side wall including a dome ring of a concrete tank and prestressed. Concerning construction method.
[0002]
[Prior art]
This type of PC tank is used for storage of water, oil, low-temperature liquefied gas, etc., but PC steel wire with prestressed sidewalls deteriorates due to corrosion during long-term use. This reduces the effective cross-sectional area of the PC steel wire.
[0003]
For this reason, the pre-stress applied to the concrete side wall against the internal pressure due to the storage fluid such as water gradually decreases, and if left as it is, the corrosion further proceeds and the PC steel wire breaks from the inside. It is necessary to carry out a repair work as soon as possible because it can lead to serious problems such as cracks in the PC tank due to the fluid pressure.
[0004]
In particular, the dome ring located on the upper end side of the side wall portion introduces a large prestress by the PC steel wire in order to counter the thrust force (force that spreads outward) generated by the load due to the weight of the dome. If the PC steel wire deteriorates due to corrosion or the like and the prestress is reduced, cracks may occur in the dome and the dome ring. Therefore, it is necessary to perform repair work in advance.
[0005]
The repair work at that time is, for example, to temporarily reduce the load on the dome by temporarily setting up a support column, etc. As a result, the work efficiency may be lowered and the construction period may be prolonged.
[0006]
In the case of an operating PC tank, the thrust force generated by the load due to the weight of the dome acts on the side wall including the dome ring, and it is in operation for repair work to eliminate this thrust force. Although it is not impossible to temporarily evacuate the PC tank and temporarily install a column or the like, it is not preferable because the economic loss is large, and it is desirable to provide means that can counter this thrust force.
[0007]
[Problems to be solved by the invention]
The present invention provides a restoration method that can restore the desired strength of a dome ring in which existing PC steel wire has deteriorated due to corrosion or the like, and effectively reduces the influence of thrust force generated by the weight of the dome. It is possible to perform repair work in a wet state, and it is possible even when the internal pressure of the stored liquid is acting on the side wall during operation, eliminating the economic loss of sleeping the PC tank and using it for a longer period of time The main purpose is to make it possible.
[0008]
[Means for Solving the Problems]
The PC tank dome ring repair method according to the present invention removes an existing PC steel wire from a dome ring provided at the upper part of a side wall portion in a state where a continuous fiber sheet is attached and reinforced on the surface of the dome. In addition to the replacement with the repairing PC steel wire, a reinforcing ring in which concrete is increased is provided on the outer periphery of the dome ring in such a manner that the replaced repairing PC steel wire is embedded.
[0009]
In this restoration method, a continuous fiber sheet is attached and reinforced on the surface of the dome to counteract the thrust force generated by the load due to its own weight, reduce the stress applied to the dome and the dome ring, and cracks, etc. Since generation | occurrence | production can be prevented, it is possible to perform the operation | work which replaces existing PC steel wire with PC steel wire for a repair easily and safely.
[0010]
In addition, reinforcement with a continuous fiber sheet increases the construction cost due to the temporary construction, which is larger than the case where it is temporarily supported by a temporary support to reduce the load on the dome. There is no possibility that the PC tank is temporarily emptied and put to sleep for temporary installation, and the temporary support column hinders the repair work, thereby reducing the work efficiency and prolonging the construction period.
[0011]
Therefore, by replacing the deteriorated existing PC steel wire with a repairing PC steel wire and providing a reinforcing ring with increased concrete beating on the outer periphery of the dome ring, the original pre-stress is restored and further extended. In particular, the continuous fiber sheet functions as a reinforcing member and anticorrosive material even after cutting and removing the existing PC steel wire during repair work, and enhances the durability of the PC tank. Can do.
[0012]
In addition, in this restoration method, even when the PC tank is in operation, the dome ring can be safely restored without receiving an excessive load, and the economical loss of sleeping the PC tank can be eliminated.
[0013]
The PC steel wire for repair in the PC tank repair method can take a form using a PC steel wire covered with a sheath.
[0014]
In this restoration method, rust prevention performance and tensile force are improved by replacing the existing PC steel wire made of bare steel wire with the PC steel wire covered with the sheath, and the number of existing PC steel wires provided in multiple stages is reduced. It is possible to replace it with a PC steel wire, and it is possible to facilitate repair work and improve durability.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a dome ring repair method for a PC tank according to the present invention will be described in detail with reference to the accompanying drawings showing preferred embodiments. FIG. 1 is a longitudinal sectional view of a main part of a PC tank to which the present invention is applied. FIGS. 2 to 7 show detailed explanatory views of the construction process of the present invention construction method, respectively.
[0016]
As shown in FIG. 1, the PC tank 1 has a dome ring 3 connected to the upper side of a cylindrical side wall 2, a dome 4 is provided at the upper end of the dome ring 3, and the dome ring 3 A PC steel wire 5 made of a bare wire is spirally wound around the outer peripheral surface of the side wall portion 2 including a protective coating layer 6 made of mortar or the like in such a manner that the PC steel wire 5 is embedded.
[0017]
When a part of the PC steel wire 5 deteriorates due to corrosion or the like during long-term use, the PC tank 1 has a reduced cross section of the PC steel wire 5 at the deteriorated portion. If the PC steel wire 5 is left as it is, the PC steel wire 5 breaks, causing a irreparable situation such as a crack in the PC tank 1, so that it is necessary to repair it immediately.
[0018]
In particular, the dome ring 3 at the upper end of the side wall 2 is subjected to a thrust force due to the weight of the dome 4 provided at the upper end being applied as a load. The ring 3 may be cracked and the dome 4 may be cracked, requiring repair in advance.
[0019]
In this restoration method, as shown in FIG. 2, a continuous fiber sheet 7 having a high tensile strength is preliminarily applied to the surface of the dome 4 to prevent cracking. The continuous fiber sheet 7 is made of, for example, an aramid fiber sheet. A bi-directional aramid fiber sheet that can be used and preferably reinforced in two directions is used and adhered to the surface of the dome 4 with an epoxy resin adhesive or the like.
[0020]
Next, the protective coating layer 6 is removed from the outer periphery of the dome ring 3 and the existing PC steel wire 5 exposed by the removal of the protective coating layer 6 is also removed, but the PC steel wire 5 is located in the lower side wall 2. If a fixing tool (not shown) is provided at the boundary with the side wall 2 to fix the PC steel wire 5 so as not to loosen, the PC steel wire 5 is placed above the fixing tool. Is cut and removed, and its outer peripheral surface is shaped (ground treatment) so as not to be uneven.
[0021]
Next, as shown in FIG. 3 and FIG. 4, a PC steel wire 8 for repair is wound around the outer periphery of the dome ring 3, and both ends are tightened with a tensioning tool 9 to tension the PC steel wire 8 and prestress is applied. The tensioning device 9 is tightened on both sides of the supporting member 10 by screwing into the supporting member 10 inserted through both ends of the PC steel wire 8 and the both end screw portions 8a and 8b of the PC steel wire 8, for example. It consists of fastening nuts 11 and 11.
[0022]
The PC steel wire 8 can be replaced with a bare steel wire without a sheath similar to the existing PC steel wire 5, but the outer periphery is coated with a sheath, has high rust prevention performance, and has a high tensile force. Use of steel wire is desirable, and because the tensile force is large, the existing PC steel wire 5 can be replaced with a smaller number of PC steel wires, the replacement work becomes easy, and the rust prevention performance is high, so the durability is improved. .
[0023]
In this way, the existing PC steel wire 5 in which a single bare steel wire is continuously wound in a spiral shape is used for repairing, in which a plurality of PC steel wires wound around each turn are arranged in parallel. Although the PC steel wire 8 is replaced, since the dome 4 is reinforced with the continuous fiber sheet 7, the existing PC steel wire 5 is removed in a lump in a state where the thrust force is reduced. It is possible to replace them at the same time.
[0024]
Next, a formwork (not shown) is provided on the outer periphery of the dome ring 3 and, as shown in FIG. As shown in FIG. 6, the reinforcing ring 12 is provided in a state in which the adjacent portion of the tendon 9 is excluded.
[0025]
Next, after tightening the fastening nuts 11, 11 of the tensioner 9 and introducing prestress to the PC steel wire 8, the decorative concrete 13 is placed in the adjacent portion including the tensioner 9 as shown in FIG. Although the restoration work is completed by finishing flush with the reinforcing ring 12, the continuous fiber sheet 7 is left as it is as a reinforcing member of the PC tank 1.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an essential part of a PC tank to be subjected to a PC tank dome ring repair method according to the present invention.
FIG. 2 is a detailed explanatory view of the construction process of the present invention construction method, and shows a state in which a dome is reinforced with a continuous fiber sheet and a protective coating layer at a repair site is removed in a longitudinal sectional view.
FIG. 3 is a detailed explanatory view of the construction process of the method of the present invention, and shows a state in which a PC steel wire for repairing is mounted on a trace after removing an existing PC steel wire in a longitudinal sectional view.
FIG. 4 is a cross-sectional view of a repaired portion including a tensioning device attached to a PC steel wire for repair in the process of FIG. 3;
FIG. 5 is a detailed explanatory view of the construction process of the method according to the present invention, and shows a state in which a reinforcing ring is provided at a repairing part equipped with a PC steel wire for repairing in a longitudinal sectional view.
FIG. 6 is a cross-sectional view of a repaired portion including a tendon attached to a PC steel wire for repair in the process of FIG. 5;
FIG. 7 is a detailed explanatory view of the construction process of the method of the present invention, and shows a state in which decorative concrete is provided at a repair location including a tendon in a cross-sectional view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 PC tank 2 Side wall part 3 Dome ring 4 Dome 5 (Existing) PC steel wire 6 (Existing) protective coating layer 7 Continuous fiber sheet 8 (For restoration) PC steel wire 9 Tension tool 10 Supporting member 11 Fastening nut 12 Reinforcement ring 13 Decorative concrete

Claims (2)

With the continuous fiber sheet attached to the surface of the dome and reinforced, the existing dome ring provided at the top of the side wall is removed and replaced with a PC steel wire for repair. A PC tank dome ring restoration method, characterized in that a reinforcing ring is provided on the outer circumference of the dome ring in an embodiment in which the repaired PC steel wire is embedded. 2. The PC tank dome ring repair method according to claim 1, wherein the PC steel wire for repair is a PC steel wire covered with a sheath.

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