JPH0443539B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to a method for repairing a cylindrical structure made of concrete and further reinforcing structural defects after repairing and restoring the cylindrical structure.

《Conventional technology》 Conventionally, cracks occur in concrete structures,
When problems occurred in terms of strength and waterproofing, epoxy resin was press-fitted into the cracks, and depending on the extent, a waterproof resin coating was applied to the inner and outer walls.

That is, since the concrete used in concrete structures has a low tensile strength, cracks are allowed in advance, and repairs are performed immediately before the problem occurs.

On the other hand, in cylindrical structures such as liquid tanks and pressure vessels, where cracks should not occur in concrete structures, if cracks occur in the vertical direction of the side wall due to internal pressure, the inside of the structure may be damaged. As the pressure changes, the width of the crack expands and contracts significantly. Therefore, it was necessary to select a waterproof material that could follow the expansion and contraction width of the crack and also withstand friction with the contents, but no suitable material was available. In order to deal with such problems, proposals have been made to repair cracks and waterproof layers in existing tanks made of concrete or the like (see Japanese Patent Laid-Open No. 52-48823).

On the other hand, it is known that concrete tanks are reinforced using prestressed concrete (see Japanese Patent Publication No. 15125/1983).

《Problems to be solved by the invention》 However, after repairing the cracks and waterproofing layer of this kind of existing reinforced concrete cylindrical structure, it is necessary to apply prestressing to the structure by post-tensioning. No repair method has been developed to prevent the recurrence of cracks in structures. In addition, there was no way to take into account the internal pressure that would be applied to an existing structure of this type during this repair work, introduce prestress in a way that corresponded to this internal pressure, and repair while reinforcing structural weaknesses.

The present invention has been made in view of the above circumstances, and its purpose is to provide a method for repairing an existing concrete cylindrical structure by which the repair can be carried out perfectly.

<Means for Solving the Problems> In order to achieve the above object, the method for repairing a cylindrical structure according to the present invention is a method for repairing an existing concrete cylindrical structure that has undergone various repairs such as repairing cracks and waterproofing layers. When repairing to reinforce a structure, first, fixing intervals corresponding to the internal pressure of the structure are set on the outer peripheral surface of the cylindrical structure at intervals in the circumferential direction and along the height direction. A plurality of buttresses for fixing tools are installed, and then a plurality of tendons are arranged in multiple stages in the height direction of the structure at fixing intervals set by the buttresses, and both ends thereof are These tendons are wound around the outer circumferential surface of the structure along the circumferential direction so as to be individually fixed to each buttress, and then prestress is applied to each of these tendons in order to bind the structure from the outer circumferential surface. and fixed on the buttress.

<<Operation>> Since the force that the outer wall of a concrete cylindrical structure receives from the outside to the inside becomes a compressive force on the concrete, the effect on the structure is almost not a problem. On the other hand, the force acting from the inside to the outside becomes tensile stress on the concrete, causing cracks in the structure,
However, in the present invention, a plurality of fixing tool buttresses are installed on the outer circumferential surface of the cylindrical structure at intervals in the circumferential direction and along the height direction. The tension members are arranged in multiple stages in the height direction of the structure at fixing intervals set by the buttresses, and are wound around the outer peripheral surface of the structure along the circumferential direction. By individually fixing these tendons to the buttresses, applying prestress to each of these tendons, and fixing them to the buttresses, the structure is tied from its outer circumferential surface, so the outer circumferential surface is tied with the tendons and constant compressive force is applied. By applying these tension materials, the compressive force provided by these tension members can cancel out the tensile stress and reinforce it, and the existing cylindrical structure can be appropriately repaired.

In particular, a buttress for the fixing device is installed which has the function of setting the fixing interval corresponding to the internal pressure of the cylindrical structure, that is, maintaining the spacing of the tension material, and the fixing interval set by this buttress is set in the height direction of the structure. By arranging a plurality of tension members in multiple stages and fixing them to each buttress, the structure can be reinforced by introducing prestress in a manner that corresponds to the internal pressure.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a reinforced concrete silo 1 containing liquid pulp material subjected to the method of the present invention. This silo 1 has a cylindrical shape, and lateral pressure from the pulp raw material contained therein acts as tensile stress on the peripheral wall 2, causing cracks and the destruction of the waterproof layer to occur quickly. To repair, first empty the inside of the silo 1 to release the lateral pressure due to the contents.

Next, epoxy resin or the like is press-fitted into the crack to seal it. Thereafter, a waterproofing agent is applied to the inner and outer surfaces of the peripheral wall 2 to form a waterproof layer.

Further, trapezoidal fixing tool buttresses 3-3 are attached and fixed to the outer peripheral surface of the peripheral wall 2 at intervals of 180 degrees.

To install the anchor buttress 3, attach the peripheral wall 2.
Drive an anchor bolt into the specified position and secure it in place.

An unbonded cable 4 is used as the tension material, and is alternately wound and fixed by a fixing tool 5 prepared on a fixing tool buttress 3-3. Note that the tension material is not limited to PC steel wire, but may also be a strand cable using long carbon fibers or aramid fibers, which do not have to worry about rust prevention.

Finally, the peripheral wall 2 is connected to the unbonded cable 4.
Introduce prestress to. In particular, a fixing tool buttress 3 is installed that has a function of setting a fixing interval corresponding to the internal pressure of the reinforced concrete silo 1, that is, maintaining the interval of the unbonded cable 4, and the height of the silo 1 is adjusted according to the fixing interval set by this buttress 3. Since a plurality of unbonded cables 4 are arranged in multiple stages in the direction and fixed to each buttress 3, the silo 1 can be reinforced by introducing prestress in a manner corresponding to the internal pressure. Specifically, the spacing becomes narrower from the top to the bottom of the peripheral wall 2, and they are arranged more densely so that the side pressure acting from the inside to the outside of the peripheral wall 2 can be evenly resisted. Also, when introducing prestress, the peripheral wall 2
In order to avoid biasing the compressive force to one point in the circumferential direction, the fixing tool buttresses 3 are arranged oppositely at two points on the outer circumferential surface, and the fixing of the unbonded cables 4 is alternately changed every 180 degrees. There is.

Details of the fixing tool buttress 3 are shown in FIGS. 3 and 4. The fixing tool buttress 3 is firmly attached to the peripheral wall 2 with anchor bolts 6. This buttress 3 consists of two longitudinally parallel girders 7-7 and a horizontal arm 8.
It is made of metal and has a support 9 attached between the upper and lower horizontal rods 8 and 8 which are adjacent to each other, so that it can sufficiently withstand the tension of the PC steel wire and ensure accuracy. It may be assembled by welding steel plates for strength reliability and economy. Note that fiber reinforced resin (FPR) or the like may be used as long as it has reliable strength. The girder 7-7 has a through hole 10 from the side.
The through hole 10 has a diameter that is large enough for the sheath of the unbonded cable 4 that is hung around the peripheral wall 2 to pass through, and the through hole 10 is for fixing the fixing tool 5.
A and the through hole 10b for passing the sheath of the unbonded cable 4 are made into one set, and a total of four through holes 10a, 10a, 10b, 10b in the left and right girders 7-7 are made into one set.

As understood from FIG. 2, the through hole 10a
is located away from the surface of the peripheral wall 2, and the through hole 1
0b is bored at a position close to the surface of the peripheral wall 2,
One unbonded cable 4 intersects within the girder 7-7, its end protrudes from the inside of the girder 7 to the outside, and after introducing prestress by pulling the protruding end with a jack or the like, the fixing device 5 It is fixed and fixed to the outer surface of the.

These one set of through holes 10a, 10a, 10b,
10b (a set of through holes) and the set of through holes directly below it, and on the side where the girder 7 contacts the peripheral wall 2, a notch 11 is provided that is large enough for the sheath of the unbonded cable 4 to pass through. An unbonded cable 4 is passed through which is fixed to the buttress 3 on the opposite side.

As described above, this fixing tool buttress 3 determines the interval at which the unbonded cable 4 is wound around the peripheral wall 2, and also takes the reaction force when introducing prestress.

Even if liquid pulp raw material is put into the silo 1, the unbonded cables 4 are arranged densely at the bottom and prestress is applied to the peripheral wall 2, so there is no lateral pressure on the peripheral wall 2 from the inside. The internal pressure is balanced by the compressive force of the unbonded cable 4, and the peripheral wall 2 is compressed from both sides by internal lateral pressure and external prestress pressure, so no cracks occur and the waterproof layer does not expand or contract due to the cracks. Since the contents are not subjected to friction at the places where the contents are raised like a film due to cracks, the proof strength as a liquid container can be maintained sufficiently.

Cracks will not occur again in the vicinity of repaired cracks.

As explained above, in this embodiment, after repairing the silo 1, a plurality of fixing devices 5 are arranged along the height direction of the silo 1, and the fixing positions of the unbonded cables 4 are separated by 180 degrees in the circumferential direction. Fixing tool 5 in the position
It is possible to introduce a homogeneous prestress. In addition, since the unbonded cable 4 is wound more closely as it goes below the silo 1, the compressive force due to the lateral pressure from the inside and the prestress from the outside applied to the peripheral wall 2 constituting the silo 1 is the unbonded cable 4. The arrangement of the cables 4 can be made uniform in both the vertical direction and the density thereof. Moreover, since the tension applied to each unbonded cable 4 is the same, the tensile force applied to the prestress introduction work, for example, jacking, can be all the same.

In addition, when repairing a cylindrical structure such as a pressure vessel that contains gas such as steam, the internal pressure is almost equal between the top and bottom of the structure, so the unbonded cable 4 should be moved upward and downward evenly. Can be wound and tensioned at intervals.

Therefore, work efficiency is high, and since the structure is bound from the outer periphery by the unbonding cable 4, a compressive force is always applied to the peripheral wall of the structure, and there is no possibility of cracks in the concrete. This has the effect of increasing the service life of the waterproof layer. As described,
The method of this embodiment is effective for repairing liquid tanks, pressure vessels, etc.

<<Effects>> In summary, according to the present invention, a plurality of fixing tool buttresses are installed on the outer peripheral surface of a cylindrical structure at intervals in the circumferential direction and along the height direction, and a plurality of tension members The tension members are arranged in multiple stages in the height direction of the structure at fixing intervals set by the buttresses, and are wound around the outer peripheral surface of the structure along the circumferential direction, and both ends of these tension members are fixed to each buttress. By applying prestress to each of these tendons and fixing them to the buttresses, the structure is bound from its outer circumferential surface, so the outer circumferential surface is tied with the tendons and compressive force is constantly applied. By applying these tension materials, the tensile stress can be canceled out and reinforced by the compressive force applied by these tension materials, and the existing cylindrical structure can be appropriately repaired.

In particular, a buttress for the fixing device is installed which has the function of setting the fixing interval corresponding to the internal pressure of the cylindrical structure, that is, maintaining the spacing of the tension material, and the fixing interval set by this buttress is set in the height direction of the structure. By arranging a plurality of tension members in multiple stages and fixing them to each buttress, the structure can be reinforced by introducing prestress in a manner that corresponds to the internal pressure.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a silo for liquid pulp raw materials to which the present invention is applied, Fig. 2 is a schematic plan view thereof, Fig. 3 is a side view illustrating the buttress for the fixing device used, and Fig. 4 is its use. FIG. 1... Silo, 2... Peripheral wall, 3... Buttress, 4... Unbonded cable, 5... Fixture,
6... Anchor bolt, 7... Girder, 8... Yokogan,
9... Support column, 10... Through hole, 11... Notch.

Claims (1)

[Claims] 1. When repairing an existing concrete cylindrical structure that has undergone various repairs, such as repairing cracks and waterproofing layers, in order to reinforce it, first, the outer circumferential surface of the cylindrical structure is coated in the circumferential direction. A plurality of fixing device buttresses are installed at intervals and along the height direction thereof, and the fixing intervals are set in accordance with the internal pressure of the structure, and then, the fixing intervals set by the buttresses are set. A plurality of tendons arranged in multiple stages in the height direction of the structure are wound around the outer peripheral surface of the structure along the circumferential direction so that both ends of the tension members are individually fixed to each buttress. and then, in order to tighten the structure from its outer peripheral surface, each of these tendons is prestressed and fixed to the buttress.