JP2013249636A - Grout reinjection method to grout unfilled cavity inside sheath for pc tendon insertion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grout reinjection method for easily performing complete grout reinjection by a simple device without leaving a cavity of a grout unfilled part when reinjecting grout into the grout unfilled part cavity remaining inside a sheath for PC tendon insertion of an existing PC structure.SOLUTION: When reinjecting grout for reinjection to a grout unfilled cavity that is positioned at an inclined part or vertical part of a PC tendon insertion sheath in an existing PC structure and has air permeability on an upper end side, a grout injection hose is connected to a lower side end of the grout unfilled cavity, the grout injection hose is communicated to a lower end of a grout injection container for storing the grout for reinjection, the grout injection container is installed such that the upper end thereof is positioned higher than the upper end of the grout unfilled cavity, and the grout for reinjection stored inside the grout injection container is injected into the cavity while adjusting an injections peed to an arbitrary speed.

Description

  The present invention is for inserting a PC tension material for injecting a reinjection grout into a cavity existing in an anchoring side end of a sheath or other inclined or vertical portion of an existing prestressed concrete (hereinafter referred to as PC) structure. The present invention relates to a method for reinjecting grout into a grout unfilled cavity in a sheath.

  In recent years, there are cavities in the end of the tension member fixing part side of the sheath for inserting the PC tension material used in the post tension type PC girder and other parts, and the internal corrosion has been regarded as a problem. Yes.

In particular, in a PC girder on an elevated road, as shown in FIG. 1, there is a portion where a PC tendon fixing portion 3 of a PC tendon 6 is provided obliquely upward under the pavement 2, and sodium chloride, calcium chloride. In places where anti-freezing agents such as magnesium chloride are actively sprayed, these anti-freezing agents penetrate into the pavement 2 together with water, enter the sheath through the PC tendon fixing part 3, and the PC tendon Corrosion has occurred.
For this reason, in recent years, a method has been developed in which grout is reinjected into a cavity formed at the end portion of the sheath of the sheath of the PC tendon material (for example, Patent Documents 1 and 2).

  In addition, it is known that a metal having a large ionization tendency has a corrosion rate of almost zero when a passivation treatment is performed on the surface thereof (Non-Patent Document 1). Prior to reinjecting the grout into the unfilled grouting cavity, a technique for forming a passive film on the surface of the PC tendon by supplying a rust preventive solution to the inner surface of the sheath and the PC tendon exposed in the cavity. developed.

Japanese Patent Laid-Open No. 2005-23693 JP 2005-23567 A

"Chemical Encyclopedia (Vol. 7)" Kyoritsu Publishing Co., 1981 October 15, issued 911 pages

  Regarding the PC tension members existing in the sheath in the existing PC structure, in particular, the grout unfilled cavities such as the end portion of the PC tension member fixing portion, particularly about the steel wire bundle, the steel stranded wire, and the steel stranded wire bundle. There is an internal void in the PC tendon itself.

  In addition, the grout unfilled cavity in the sheath is high in humidity and is often stagnant. When the rust preventive treatment is performed with the rust preventive aqueous solution such as the above-described lithium sulfite aqueous solution, the rust preventive agent is used. It is conceivable that the aqueous solution remains.

  When grout re-injection is performed in such a stagnant sheath cavity, if the grout injection speed is high, a part of the air in the cavity, the air in the internal space of the PC tendon, and the liquid that remains are retained. The re-injection grout is filled up to the top without being fully pushed up, and as time passes, air and liquid slowly move upward, causing air and liquid to accumulate at the top, reducing fillability. There is a problem to do.

  Furthermore, in the case of construction using a vacuum pump for the above grout reinjection, there is a possibility that air and moisture will be mixed into the grout for reinjection. There is a problem that the liquid moves upward and an air reservoir or a liquid reservoir is formed in the upper portion, and the filling property is lowered.

  If air pools or liquid pools after re-injection occur as described above, in order to remove them, a method of extruding to the back side of the upper PC tension material fixing part or the ventilation hose by repressurization is considered. However, there is a problem that the repressurization necessary in that case cannot be quantitatively grasped.

  As a general method of repressurization, there is a method in which a grout injection hose or an exhaust hose is added about 1 m, and after repressurization by a pump, the hose is bent and closed, but the injection pressure is too high. There is a risk of re-injection grout leakage from the re-injection hole, the re-pressing force is limited and cannot be excessive, and if the re-pressing force is insufficient, the upper air reservoir or liquid reservoir cannot be removed, There is a problem that a cavity remains as an unfilled portion.

  In view of such a conventional problem, the present invention provides a cavity of the grout unfilled portion as described above upon reinjection of the grout into the grout unfilled cavity remaining in the PC tension member insertion sheath of the existing PC structure. It is an object of the present invention to provide a method for grout reinjection into a grout unfilled cavity in a sheath for inserting a PC tendon, in which complete grout reinjection can be easily performed with a simple device.

  The characteristic of the grout reinjection method to the grout unfilled cavity in the PC tendon insertion sheath according to the invention of claim 1 is located in the inclined part or the vertical part of the PC tendon penetration sheath in the existing PC structure. And when reinjecting the grout for reinjection into the grout unfilled cavity having air permeability on the upper end side, a grout inject hose is connected to the lower end of the unfilled cavity of the grout, The grout injection container for accommodating the reinjection grout is communicated with a lower end portion of the grout injection container, and the grout injection container is installed such that the upper end thereof is higher than the upper end of the unfilled hollow portion of the grout, The purpose is to inject the reinjection grout accommodated in the grout injection container into the cavity while adjusting the injection speed to an arbitrary speed.

  According to a second aspect of the present invention, in addition to the structure of the first aspect, the air permeability on the upper end side of the grout unfilled cavity portion is a ventilation hose inserted from the outside of the sheath into the upper end of the cavity portion. There is to be maintained by.

  According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the adjustment of the injection rate of the reinjection grout is performed by adding the reinjection grout to the grout injection container per unit time. The purpose is to control the injection rate by natural flow by adjusting the amount.

  According to a fourth aspect of the present invention, in addition to the configuration of the first or second aspect, the adjustment of the injection rate of the reinjection grout is performed in the reinjection grout liquid in the reinjection grout container. Waiting for the natural descent of the surface to intermittently add a re-injection grout into the grout-injecting container, and controlling the injection rate by the natural flow of the re-injection grout by adjusting the additional amount is there.

  According to a fifth aspect of the present invention, in addition to any one of the first to fourth aspects, the re-injection in the cavity is caused by a change in the natural descent speed of the re-injection grout liquid surface in the grout injection container. After confirming that the liquid level of the grout for injection has reached the uppermost part of the cavity, the height of the grout liquid surface for reinjection in the grout injection container is set higher than the PC tendon fixing part by a predetermined height. There is to maintain.

  According to the present invention, as described in claim 1, a grout injection hose is communicated with a lower end portion of a grout injection container for containing a reinjection grout to be injected, and the upper end of the grout injection container is connected to the upper end. Installed so as to be higher than the upper end of the grout unfilled cavity, and by injecting into the cavity while adjusting the injection speed of the reinjection grout accommodated in the grout injection container, According to various conditions such as the viscosity of the reinjection grout used and the gap spacing in the cavity, it can be injected from the bottom of the cavity without entraining air or moisture in the reinjection grout. It is possible to minimize the occurrence of air accumulation and water accumulation.

  According to the present invention, as described in claim 2, the air permeability on the upper end side of the grout unfilled cavity is maintained by the ventilation hose inserted from the outside of the sheath into the upper end of the cavity. Even when there is no air permeability at the upper end of the grouting unfilled cavity, it can be carried out properly.

  In the present invention, the adjustment of the reinjection grout speed according to claim 3 is based on natural flow by adjusting the additional amount per unit time of the reinjection grout into the grout injection container. By controlling the injection rate, the slow adjustment of the injection rate is facilitated.

  According to the present invention, as described in claim 4, the adjustment of the injection rate of the reinjection grout is performed by waiting for a natural descent of the reinjection grout surface in the grout injection vessel. By adding the re-injection grout intermittently and adjusting the addition amount to control the injection speed of the re-injection grout under the natural flow, the filling condition in the cavity is indirectly grasped. The grout can be reinjected according to the situation.

  According to the present invention, the liquid level of the reinjection grout in the cavity reaches the top of the cavity by the change in the natural descent rate of the reinjection grout liquid level in the grout injection container. After confirming that the grouting liquid level in the grouting container is maintained at a predetermined height higher than the upper end of the unfilled grouting cavity, the inside of the cavity can be re-injected. Even when air accumulation or liquid puddle occurs due to the rise of air or moisture after filling with grout, re-pressurization is continued for a long time due to the liquid level higher than the PC tendon fixing part in the grout injection container. The grout is reinjected without leaving an air or liquid reservoir.

The outline of the vicinity of the fixing part when the upper end of the grout unfilled cavity of the PC structure embodying the present invention is a PC tendon fixing part is shown, (a) is a longitudinal side view, (b) is a longitudinal front view. It is. FIG. 2 is a cut end view showing the inside of the sheath at the position AA in FIG. 1. It is a longitudinal cross-sectional view which shows the outline of the ventilation | gas_flow inspection of the previous step which implements this invention. It is sectional drawing which shows the case where the ventilation property of the upper end side of the said grout unfilled hollow part of the PC tension material fixing | fixed part side part in a sheath is given with the hose for ventilation | gas_flowing. It is explanatory drawing which shows the outline of an example of the grout reinjection method in this invention, (a) is a vertical side view, (b) is a vertical front view. It is a partial sectional view showing another sheath cavity examples for implementing the present invention. It is a partial sectional view showing another example of the sheath cavity to implement the present invention.

  Next, aspects of the present invention, grout unfilled cavity 12 of the PC structure is formed on the lower side of the PC tendon fixing portion 3, the upper end of the cavity 12 is a PC tendon fixing portion 3 described rust solution injection method when.

  FIG. 1 shows a cross section of the vicinity of a PC tendon fixing portion of a PC structure embodying the present invention. In the figure, reference numeral 1 is a PC girder, and 2 is a pavement formed thereon. The PC girder 1, the upper surface provided with a PC tendon fixing portion 3, the PC tendon fixing unit 3, a female cone 4 embedded in PC girder 1, the male cone 5 fits into a tapered hole therein the a, the end of the PC tendon 6 by both cones 4 and 5, are fixed by maintaining the tension.

  In this example, we use those a plurality of single wires 7 as PC tendon 6 in a bundle, but has been established by sandwiching each single wire 7 between both cone 4 and 5 In addition, PC tendons 6, PC steel rod using single wire, may be a PC strand by twisting a plurality of single wires, the structure of the case PC tendon fixing unit is used in the various PC tendon it may be a case of using the previous structure.

The PC tension material fixing portion 3 is provided in a recess 8 formed on the surface of the PC girder 1 and after the PC tension material 6 is tension-fixed, a grout operation and post-processing are performed, and a fixing portion protective concrete 9 is placed. Thus, the PC tendon fixing part 3 is protected by filling the recess 8.
A sheath 10 is connected to the female cone 4 of the PC tendon fixing portion 3, and a PC tendon 6 is inserted into the sheath 10. The sheath 10 is inclined downward at a position close to the PC tendon fixing portion 3.

  When such an existing PC girder 1 is newly installed, the grout 11 is often injected from one side of the sheath 10 by a pressure pump. In recent years, the pressure is reduced by a vacuum pump from the other side. The grout filling operation is performed in combination, and the grout is sealed in a state where the entire area in the sheath leading to the PC tendon fixing part 3 is filled. There is a case where the grouting unfilled cavity 12 is formed due to a cause such as the air rising and collecting in the sheath 10 on the PC tendon fixing portion side.

  In the present invention, the grout for reinjection is reinjected into the cavity 12 by natural flow without removing the fixing part protective concrete 9 in the recess 8, and the PC tension material fixing part 3 which is the uppermost part of the cavity 12 is injected into the cavity 12. Until refilled grout.

  Therefore, first, a ventilation test is performed on the PC tendon material fixing portion 3, that is, the portion other than the upper end of the cavity 12. In this operation, as shown in FIG. 2, the bottom or side surface of the PC girder 1 is partially suspended until the sheath 10 is exposed, and a hose insertion hole 15 is opened in the exposed portion of the sheath 10. A pressure resistant grout reinjection hose 16 is inserted into the hose insertion hole 15 and the insertion portion is sealed.

  In this state, the grout reinjection hose 16 is communicated with the vacuum pump 23 through the vacuum gauge 20, the on-off valve 21, and the decanter 22 in this order. In this state, the inside of the cavity 12 is depressurized by the vacuum pump 23, and the generation site of the air suction sound generated at that time is found using a microphone or a stethoscope, and the part is a repair material for maintaining airtightness, For example, it is sealed with a quick-drying two-component epoxy resin.

  By this ventilation test, the ventilation portion other than the PC tension material fixing portion 3 is closed to inspect the PC tension material fixing portion 3, that is, the upper end portion of the cavity 12 for air permeability, and the PC tension material fixing portion 3 is ventilated. When the property is confirmed, reinjection of the reinjection grout by the natural flow method described later is performed as it is.

On the other hand, if there is no air permeability at the upper end portion of the cavity 12 or if there is insufficient air permeability for exhaust during injection of a reinjection grout described later, as shown in FIG. A hose insertion hole is opened at a position different from the insertion portion of the reinjection hose 16 and the ventilation hose 13 is inserted to ensure air permeability. Thereafter, the reinjection grout is reinjected by the natural flow method.
In addition, as an example suitable for the grout for reinjection, there is one in which the flow in the modified JASS method continues for 250 hours or more for 5 hours.

  As shown in FIG. 5, the pouring operation is performed by placing a grout reinjection hose 16 connected to the hose insertion hole 15 at the lower end of a grout injection container 17 comprising a vertical pipe for injecting the reinjection grout by natural flow. The reinjection grout 18 which is connected and accommodated in the grout injecting container 17 is naturally flowed to be injected into the cavity 12.

  At this time, the grout injecting container 17 is transparent so that the liquid level 18a inside thereof can be visually observed, and the height of the liquid level 18a is higher than the liquid level 18b of the reinjecting grout 18 injected into the cavity 12. Adjust so as to be higher by a predetermined height. As shown in FIG. 5 (b), this is caused to flow down spontaneously due to the water head difference h between the two liquid levels 18a and 18b. At the beginning of reinjection, the height of the liquid level 18a in the grout injection container is hose. Injection is started at a position slightly higher than the height of the insertion hole 15.

  When the descent of the liquid level 18a in the grouting container stops or the descending speed becomes below a certain level, the grouting container 17 is moved upward, or a predetermined amount of the reinjecting grouting 18 is put into the container 17. To increase the water head difference h from the liquid level 18b in the cavity. In this way, the injection rate of the reinjection grout 18 is adjusted by adjusting the injection amount per unit time from the grout injection container 17.

In addition, the injection rate may be adjusted by adjusting the reinjection grout addition amount per unit time into the grout injection container 17. For example, the reinjection grout is added every minute. The additional amount may be changed by 100 cc or 200 cc.
By doing in this way, the grout injection | pouring speed | rate can be made still slower than the injection | pouring by a hand pump, and the air and water | moisture content mixed in the grout for reinjection can be reduced.

  In addition, by observing the change in the height of the liquid level 18a in the grout injection container, it is possible to indirectly grasp the injection state of the reinjection grout in the cavity. After observing the change in the height of the liquid level 18a in the grouting container, it is confirmed that the liquid level 18b in the cavity has reached the top of the cavity, and then the height of the liquid level 18a in the grouting container The PC tension material fixing unit 3 is maintained higher than a predetermined height.

  As a result, even when the liquid level 18a in the grouting container reaches the top of the cavity once, the air in the internal space of the PC tendon and the moisture in the cavity rise to cause an air pool or a liquid pool. Therefore, the re-pressurizing pressure for removing these is surely applied at a low pressure for a long time.

  Incidentally, the above-described embodiments, the upper end of the cavity of the inclined PC tendon insertion within sheath, the case has been described where a PC tendon deposition part, the addition, PC tendon insertion sheath directed vertically and the cavity of the vertical of PC tendon fixing subordinates are, cavity 12a of the inclined portion caused by the previous flow of grout in a case where the PC tendon insertion sheath 10, as shown in FIG. 6 are arranged in a shape waving up and down, as shown in FIG. 7, may be performed with respect to the cavity 12b of the inclined portion is formed by producing collapse in PC tendon insertion sheath 10.

DESCRIPTION OF SYMBOLS 1 PC girder 2 Pavement 3 PC tension material fixing | fixed part 4 Female cone 5 Male cone 6 PC tension material 7 Single wire 8 Recess 9 Fixing part protection concrete 10 PC tension material insertion sheath 11 Grout 12, 12a, 12b Cavity 13 Ventilation hose 15 Hose insertion hole 16 Grout reinjection hose 17 Grout injection container 18 Reinjection grout 18a Grout injection liquid level 18b Cavity liquid level 20 Vacuum gauge 21 On-off valve 22 Decanter 23 Vacuum pump h Water head difference

Claims (5)

When reinjecting the grout for reinjection into the grout unfilled cavity portion which is located in the inclined portion or the vertical portion of the PC tendon insertion sheath in the existing PC structure and has air permeability on the upper end side,
A grout injection hose is connected to the lower end of the unfilled grouting cavity,
The grout injection hose communicates with the lower end of the grout injection container for containing the reinjection grout,
The grouting container is installed so that the upper end of the grouting container is higher than the upper end of the unfilled cavity, and the grouting container accommodated in the grouting container is adjusted to an arbitrary injection speed. A method for reinjecting a grout into a non-filled cavity in a sheath for inserting a PC tendon, which is characterized by being injected into the cavity.   2. The grout reinjection into the grout unfilled cavity according to claim 1, wherein the air permeability of the upper end side of the grout unfilled cavity is maintained by a ventilation hose inserted from outside the sheath into the upper end of the cavity. Method.   3. The PC tension according to claim 1, wherein the adjustment of the injection rate of the reinjection grout controls the injection rate by adjusting an additional amount per unit time of the reinjection grout to the grout injection container. A method for reinjecting grout into an unfilled cavity in a sheath for material insertion.   Adjustment of the injection rate of the reinjection grout is performed by intermittently placing the reinjection grout in the grout injection container after waiting for the natural drop of the reinjection grout liquid level in the container. The grouting reinjection to the unfilled grouting cavity in the sheath for inserting a PC tendon according to claim 1 or 2, wherein the grouting rate of the grouting for reinjection is controlled by adjusting the additional amount. Method.   After confirming that the liquid level of the reinjection grout in the cavity has reached the top of the cavity by the change in the natural descent rate of the reinjection grout liquid level in the grout injection container, the inside of the grout injection container 5. The grout unfilled in the sheath for inserting the PC tendon material according to any one of claims 1 to 4, wherein the height of the reinjection grout liquid surface is maintained by a predetermined height higher than the PC tendon material fixing part. Grout re-injection method into the cavity.

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