JP2004131968A - Repair method for dome ring of pc tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a repair method for an existing dome ring 3 with deteriorated PC wire 5 capable of recovering the specified strength thereof, particularly allowing the repair method to be performed in the state of the effect of a thrust force generated by the self-weight of the dome 4 to be effectively lowered, allowed to be performed even when the internal pressure of stored liquid acts on the side wall part 2 thereof during operation, capable of eliminating such an economical loss that a PC tank 1 is rested, and allowing the dome to be used for a long period. <P>SOLUTION: In this repair method for the dome ring of the PC tank, with a continuous fiber sheet 7 is applied onto the surface of the dome 4 for reinforcement, existing PC wire 5 is removed from the dome ring 3 installed on the upper part of the side wall part 2 to replace the PC wire with a repair PC wire 8, and a reinforcement ring 12 reinforced by concrete placed on the outer periphery thereof in such a manner that the replaced repair PC wire 8 is buried therein is installed on the dome ring 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dome ring restoration in a wound prestressed concrete tank (hereinafter referred to as a PC tank) in which a tension member such as a PC steel wire is wound around a side wall including a dome ring of a concrete tank to apply prestress. Concerning the construction method.
[0002]
[Prior art]
This type of PC tank is used for storing water, petroleum, or low-temperature liquefied gas, but the PC steel wire that has been prestressed on the side wall deteriorates due to corrosion during long-term use. This reduces the effective area of the PC steel wire.
[0003]
For this reason, the prestress applied to the concrete side wall gradually decreases against the internal pressure due to the storage fluid such as water, and if left as it is, the corrosion further progresses and the PC steel wire breaks and The fluid pressure may cause a serious problem such as cracking of the PC tank, so it is necessary to carry out repair work as soon as possible.
[0004]
In particular, the dome ring located on the upper end side of the side wall portion introduces a large prestress by a PC steel wire in order to oppose the thrust force (force spreading outward) generated by the load due to the weight of the dome, When the PC steel wire is deteriorated due to corrosion or the like and the prestress is reduced, cracks may be generated in the dome and the dome ring, so it is necessary to carry out restoration work in advance.
[0005]
In this case, for example, if the pillars are temporarily installed to reduce the load on the dome, the temporary installation of the pillars etc. will be large and the construction cost will rise, and the temporary pillars will hinder the repair work. As a result, the work efficiency may be reduced and the construction period may be prolonged.
[0006]
In the case of an operating PC tank, the thrust force generated by the load of the dome due to its own weight acts on the side wall including the dome ring. It is not impossible to temporarily empty the PC tank and temporarily install columns, but it is not preferable because the economic loss is large, and it is desirable to provide a means capable of countering this thrust force.
[0007]
[Problems to be solved by the invention]
The present invention provides a restoration method capable of restoring the expected strength to a dome ring in which an existing PC steel wire has deteriorated due to corrosion or the like, and particularly effectively reduces the effect of thrust force generated by the weight of the dome. Repair work can be performed while the storage tank is operating, and even when the internal pressure of the stored liquid is acting on the side walls during operation, eliminating the economical loss of dormant PC tanks and using for a longer period of time Its main purpose is to enable.
[0008]
[Means for Solving the Problems]
In the dome ring repair method for a PC tank according to the present invention, an existing PC steel wire is removed from a dome ring provided on an upper portion of a side wall portion in a state where a continuous fiber sheet is adhered to the surface of the dome and reinforced. The replacement PC steel wire is replaced, and a reinforcing ring made of concrete is additionally provided on the outer periphery of the dome ring so as to bury the replaced repair PC steel wire.
[0009]
In this restoration method, by applying a continuous fiber sheet to the surface of the dome and reinforcing it, it counters the thrust force generated by the load due to the weight of the dome, reduces the stress applied to the dome and the dome ring, and reduces cracks etc. Since the occurrence can be prevented, the work of replacing the existing PC steel wire with the repairing PC steel wire can be performed easily and safely.
[0010]
Reinforcement with a continuous fiber sheet, for example, temporarily increases the construction cost and increases the construction cost, as compared to the case of temporarily supporting columns and supporting them with temporary columns to reduce the load on the dome. There is no danger that the PC tank is temporarily emptied and put to sleep for temporary installation, and there is no danger that the temporarily installed columns hinder the restoration work, lower the work efficiency and prolong the construction period.
[0011]
Therefore, by replacing the deteriorated existing PC steel wire with a repairing PC steel wire and providing a reinforcing ring made of concrete on the outer periphery of the dome ring, the original prestress is restored, and the PC steel wire is restored for a longer period of time. In particular, continuous fiber sheets function as reinforcing members and anticorrosion materials after repairing, as well as cutting and removing existing PC steel wires during repair work, and improve the durability of PC tanks. Can be.
[0012]
Further, according to this restoration method, even when the PC tank is operating, the restoration work can be performed safely without receiving an excessive load on the dome ring, 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 may employ a form in which a PC steel wire covered with a sheath is used.
[0014]
In this repair method, rust prevention performance and tensile force are improved by replacing the existing PC steel wire with bare steel wire with a PC steel wire covered with a sheath, and the existing PC steel wire provided in multiple stages is reduced in number. Can be replaced with a PC steel wire, and the repair work can be facilitated and the durability can be improved.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method of repairing a dome ring of a PC tank according to the present invention will be described in detail with reference to the accompanying drawings showing a preferred embodiment thereof. FIG. 1 is a longitudinal sectional view of a main part of a PC tank to which the present invention is applied. Drawing, Drawing 2-Drawing 7 show the detailed explanatory view of the construction process of the method of the present invention, respectively.
[0016]
As shown in FIG. 1, a dome ring 3 is continuously provided on an upper side of a side wall portion 2 formed in a cylindrical shape in a PC tank 1. A dome 4 is provided at an upper end of the dome ring 3 and a dome ring 3 is provided. Is wound spirally around the outer peripheral surface of the side wall portion 2 including a wire, and a protective coating layer 6 of mortar or the like is applied in a manner in which the PC steel wire 5 is embedded.
[0017]
In the PC tank 1, when a part of the PC steel wire 5 is deteriorated due to corrosion or the like during long-term use, the cross section of the PC steel wire 5 is reduced at the deteriorated portion, so that the prestress is reduced and the internal pressure of the storage fluid is reduced. If the PC steel wire 5 is left unattended, the PC steel wire 5 will be broken, causing an unrepairable situation such as cracking of the PC tank 1. Therefore, it is necessary to repair the steel wire immediately.
[0018]
In particular, the dome ring 3 provided at the upper end of the side wall portion 2 is subjected to a thrust force due to the weight of the dome 4 provided at the upper end as a load. The ring 3 may be cracked, and the dome 4 may be cracked, requiring repair in advance.
[0019]
In this repair method, as shown in FIG. 2, a continuous fiber sheet 7 having a high tensile strength is previously applied to the surface of the dome 4 to prevent cracks and is reinforced. The continuous fiber sheet 7 is, for example, an aramid fiber sheet. Preferably, a bidirectional aramid fiber sheet that can be reinforced in two directions is used, and is 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 removing the protective coating layer 6 is also removed. When the PC steel wire 5 is fixed so that the PC steel wire 5 is not loosened by providing a fixing device (not shown) at the boundary portion with the side wall portion 2, the PC steel wire 5 is positioned above the fixing device. Is cut and removed, and its outer peripheral surface is shaped (base treatment) so that there is no unevenness.
[0021]
Next, as shown in FIGS. 3 and 4, a PC steel wire 8 for restoration 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 to reduce prestress. For example, the tensioning member 9 is screwed to both ends of the PC steel wire 8 and screwed to the threaded portions 8a and 8b of both ends of the PC steel wire 8 and tightened on both sides of the PC steel wire 8, for example. It is composed of fastening nuts 11,11.
[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 covered with a sheath, so that the PC steel wire has high rust prevention performance and large tensile force. The use of steel wire is desirable, and since the tensile force is large, the existing PC steel wire 5 can be replaced with a smaller number of PC steel wires, and the replacement work is facilitated, and the durability is improved because of high rust prevention performance. .
[0023]
In this way, the existing PC steel wire 5 in which one bare steel wire is spirally wound continuously is used for repair, in which a plurality of PC steel wires wound in every turn are arranged in parallel. The PC steel wire 8 is replaced. Since the dome 4 is reinforced by the continuous fiber sheet 7, the existing PC steel wire 5 is collectively removed in a state where the thrust force is reduced, and the PC steel wire 8 is replaced. It is possible to substitute 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. 5, a post-cast concrete is cast in a mode in which the PC steel wire 8 is embedded, and the reinforcing ring 12 is provided. As shown in FIG. 6, the reinforcing ring 12 is provided in a state excluding a portion adjacent to the tension member 9.
[0025]
Next, after fastening the fastening nuts 11 and 11 of the tension member 9 to introduce a prestress to the PC steel wire 8, as shown in FIG. 7, a decorative concrete 13 is poured into an adjacent portion including the tension member 9, The repair work is completed by finishing the reinforcing ring 12 flush with the reinforcing ring 12, but 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 a main part of a PC tank to which a dome ring repair method for a PC tank according to the present invention is applied.
FIG. 2 is a detailed explanatory view of a construction step of the method of the present invention, in which a dome is reinforced with a continuous fiber sheet, and a state in which a protective coating layer at a repair location is removed is shown in a longitudinal sectional view.
FIG. 3 is a detailed explanatory view of a construction step of the method of the present invention, and shows a state in which a repairing PC steel wire is attached to a trace where an existing PC steel wire is removed.
FIG. 4 is a cross-sectional view showing a repair portion including a tensioning device attached to the repairing PC steel wire in the process of FIG. 3;
FIG. 5 is a detailed explanatory view of a construction step of the construction method of the present invention, and shows a state in which a reinforcing ring is provided at a repair location where a PC steel wire for repair is mounted, in a longitudinal sectional view.
FIG. 6 is a cross-sectional view showing a repair portion including a tensioning device attached to the repairing PC steel wire in the process of FIG. 5;
FIG. 7 is a detailed explanatory view of a construction step of the method of the present invention, and shows a state in which decorative concrete is provided at a restoration location including a tensioning tool 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 repair) PC steel wire 9 Tensile device 10 Pressure member 11 Fastening nut 12 Reinforcement ring 13 Decorative concrete

Claims (2)

With the continuous fiber sheet adhered to the surface of the dome and reinforced, the existing PC steel wire is removed from the dome ring provided at the upper part of the side wall and replaced with a repair PC steel wire. A method for repairing a dome ring of a PC tank, wherein a reinforcing ring made of concrete is additionally provided around the dome ring so as to bury the repaired PC steel wire. The method for repairing a dome ring of a PC tank according to claim 1, wherein the repairing PC steel wire uses a PC steel wire covered with a sheath.

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