JP2018184715A - Method for repairing crack in underwater part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for repairing a crack in an underwater part, which can uniformly fill a crack in an underwater part with a filling material by a simple process.SOLUTION: In a method for repairing a crack in an underwater part of a concrete structure, a sheet material 11 made of an elastic material is fixed to a surface S of an underwater part with a crack CR so as to cover a crack; by injecting an underwater inseparable first filling material through an injection part of the sheet material, the first filling material 21 is filled in the crack leaving part 30 on a side of a deepest part of the crack; an underwater inseparable second filling material which is larger in fluidity than the first filling material is injected into the remaining part through an injection pipe 15 extending into the crack.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for repairing a crack in an underwater part of a concrete structure.

  In various concrete structures such as revetments, quay walls, and dams, defects such as cracks may occur in the underwater part that comes into contact with water during operation. As a method for repairing cracks in concrete in the underwater part, Patent Document 1 forms a groove having a shape along a crack on the surface of a concrete structure, and an injection pipe and an injection confirmation pipe are inserted into the groove from the upper end of the groove. Inserting and applying underwater curing coating for concrete to the surface in the groove to form a coating film, embedding a blocking member in the groove in which this coating film is formed to form a repair region, and then injecting pipe A repair method is disclosed in which an underwater curing type concrete injection for concrete is injected via a filler to fill the crack with the injection (summary, FIG. 1).

  In Patent Document 2, when repairing a cracked portion that opens to the surface of a concrete structure and extends from the surface to the inside, a cement is formed by leaving an injection hole forming portion with respect to the opening of the cracked portion existing on the concrete surface. After rubbing the paste, an aqueous solution of silicate is applied onto the rubbed cement paste, and the reaction hardening filler seals the opening part of the cracked part, while forming at the inlet forming part. A silicate aqueous solution or a cement paste is press-fitted through the inlet, introduced to the deep part of the cracked part, and the gap in the cracked part is filled, and then the cement paste is rubbed into the inlet forming site and the silicate. Disclosed is a repair method in which aqueous solution is sequentially applied or silicate aqueous solution is applied so as to close the injection port formation site ( About, Figure 1).

  In Patent Document 3, a light-transmitting sheet material is fixed so as to cover a crack on the surface of a cracked underwater part generated in a concrete structure, and is not separable in water through an injection part formed on the surface of the sheet material. Disclosed is a method for repairing cracks in the underwater part in which the filler material is injected into the crack by injecting a plastic grout material as a filler, and the filling state of the filler material is confirmed through the light-transmitting sheet material (summary). , FIG. 4).

Japanese Unexamined Patent Publication No. 2005-23723 JP 2007-9487 JP 2017-8718

  According to the repair method of Patent Document 1, before filling the crack with the underwater curable injecting agent for concrete, a groove having a shape along the crack in the surface of the concrete structure is formed, and the surface in the groove is formed. It is necessary to form a coating film by applying an underwater curable coating agent for concrete, and to form a repair region by embedding a blocking member in a groove in which the coating film is formed.

  According to the repair method of Patent Document 2, a cement paste is rubbed into an opening of a cracked portion existing on a concrete surface, and a silicate aqueous solution is applied onto the rubbed cement paste, and a reaction hardening filler is used. It is necessary to seal the opening part of the cracked part.

  In each method of Patent Documents 1 and 2, an underwater-curing coating agent for concrete is applied to the surface of a groove formed along a crack to form a coating film, or an opening in a crack portion of a concrete surface It is necessary to seal the part with a reaction hardening filling with cement paste and silicate aqueous solution, but the process of forming such a coating film and seal is complicated, and if this process is unnecessary, the repair process is simplified. be able to. On the other hand, when repairing an underwater part, it is necessary to discharge | emit the water in a crack at the time of filling with a filling material.

  According to the method for repairing cracks in the underwater part of Cited Document 3, when filling the cracks with an underwater non-separable plastic grout material as the filling material, if the opening width of the cracks becomes narrow, the discharge of water in the cracks is insufficient. Thus, there is a problem that the filling material is difficult to be uniformly filled in the cracks.

  An object of the present invention is to provide a method for repairing a crack in an underwater part that can uniformly fill the crack in the underwater part with a filling material in a simple process.

  An underwater crack repairing method for achieving the above object is a method of repairing a crack in the underwater part of a concrete structure, and a sheet material made of an elastic material is applied to the surface of the underwater part with a crack. The first filling material is fixed to cover and injected with the first filling material that is not separable in water through the injection portion of the sheet material, so that the first filling material has a part of the deepest portion of the crack in the crack. The second filling material, which is left to be filled and which is more fluid than the first filling material and is inseparable in water, is injected into the part through an injection tube extending into the crack.

  According to this method for repairing cracks in the underwater part, the cracks on the surface of the underwater part are covered with a fixed sheet material, and the first filling material is filled from the injection part of the sheet material. At this time, the first filling material is However, because the fluidity is relatively small, a part of the deepest part of the crack is not filled, but the second filling material having a relatively large fluidity is then filled through the injection pipe extending into the crack. Therefore, even if the width of the crack is narrowed, the second filling material can be easily injected into the deepest part, and the second filling material can be filled into the remaining part. The material can be uniformly filled in the cracks, and water can be sufficiently discharged from the cracks. In addition, since the sheet material only needs to be fixed to the surface of the cracked underwater part, filled with the first filling material, and then filled with the second filling material, Cracks can be repaired.

  In the method for repairing a crack in the underwater part, a drain pipe for discharging the water in the part to the outside at the time of filling the second filling material is installed through the sheet material before filling the first filling material. It is preferable. This drain pipe can reliably drain water from the remaining part of the crack.

  Further, a plurality of the drainage pipes are installed apart in the extension direction of the cracks, and when the second filling material is filled, the leakage of the second filling material from the drainage pipes is confirmed in the part. It is preferable to confirm the filling position of the second filling material. By confirming the leakage of the second filling material from each drain pipe installed away from the extending direction of the crack, the filling position of the second filling material in the remaining part can be confirmed. The filling status of the filling material can be easily grasped.

  In addition, an unfilled portion not filled with the first filler material is formed at one end of the crack when filling the first filler material, and the second filler material is injected into the part through the unfilled portion. It is preferable to do. Thereby, for example, even when the opening width on the crack surface is narrow and the injection tube cannot be inserted into the crack, the second filling material can be injected into the remaining part through the unfilled portion.

  The sheet material is made of a light transmissive material, and the filling state of the first filling material is confirmed through the light transmissive sheet material, thereby grasping the filling state on the crack surface of the first filling material. can do.

  Moreover, it is preferable to provide at least two injection parts in the sheet material. Thereby, the injection | pouring position of the 1st filling material can be changed, the 1st filling material can be inject | poured from one injection | pouring part, and the water in a crack can be discharged | emitted from another injection | pouring part.

  According to the method for repairing a crack in an underwater part of the present invention, the filler material can be uniformly filled in a crack in the underwater part of a concrete structure by a simple process.

It is a figure for demonstrating the crack repair method of the underwater part by this embodiment, the front view which shows the surface of the underwater part in which a crack exists (a), The front view which shows the sheet | seat material arrange | positioned on the surface of the underwater part (b) ) And a longitudinal sectional view (c) schematically showing cracks in the underwater portion where the sheet material and the injection pipe / drain pipe are arranged. It is the longitudinal cross-sectional view (a)-(c) corresponding to FIG.1 (c) for demonstrating each process of the crack repair method of the underwater part by this embodiment. It is a flowchart for demonstrating each process S01-S09 of the crack repair method of the underwater part by this embodiment. FIG. 2 is a partial cross-sectional view schematically showing a state where a tip of a hand gun is inserted for injection of a first filling material into a cross-shaped cut of the light-transmitting elastic sheet material of FIG. 1. It is a longitudinal cross-sectional view corresponding to Fig.2 (a) for demonstrating another example which installed the some drainage pipe in the crack repairing method of the underwater part by this embodiment. It is a longitudinal cross-sectional view corresponding to Fig.2 (a) for demonstrating another example which provided the unfilled part of the 1st filling material in the crack one end in the crack repairing method of the underwater part by this embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a method for repairing a crack in an underwater portion according to the present embodiment. FIG. 1A is a front view showing the surface of the underwater portion where a crack exists, and FIG. 1B is a front view showing a sheet material arranged on the surface of the underwater portion. It is a longitudinal cross-sectional view (c) which shows roughly the crack of the underwater part by which the figure (b) and a sheet | seat material, and an injection pipe and a drain pipe are arrange | positioned. FIG. 2 is a longitudinal sectional view (a) to (c) corresponding to FIG. 1 (c) for explaining each step of the underwater cracking repairing method according to the present embodiment.

  As shown in FIG. 1 (a), when there is an open crack CR on the surface S of the underwater part C that contacts the water of the concrete structure, the surface S of the underwater part C as shown in FIGS. 1 (b) and 1 (c). The light-transmitting elastic sheet material 11 is fixed using a plurality of fixing means such as concrete nails. The elastic sheet material 11 is configured to have a size so as to cover the crack CR appearing on the surface S of the underwater portion C in FIG.

  The light-transmitting elastic sheet material 11 is formed with a plurality of cross-shaped cuts 12a to 12f. The cuts 12a to 12f can be formed on the surface of the elastic sheet material 11 by simple cutting with, for example, a cutter knife. The plurality of cuts 12a to 12f function as an injection portion when the filling material is injected, and also function as a drainage portion when water in the crack CR is discharged during injection.

  The plurality of cuts 12a to 12f are formed according to the shape, length, and direction of the crack CR existing on the surface S of the underwater portion C. For example, as shown in FIG. 1 (a), when the crack CR exists substantially in a straight line in the vertical direction, the cross-shaped centers of the plurality of cuts 12a to 12f are in the vertical direction as shown in FIG. 1 (b). The lowermost cut line 12a is formed near the lower end of the crack CR, and the uppermost cut line 12f is formed near the upper end of the crack CR. In addition, when the crack is inclined with respect to the vertical direction, the plurality of cuts are formed in accordance with the inclination, and when the crack extends in the horizontal direction, the crack is formed in the horizontal direction. , Formed according to the bend.

  Moreover, as the light-transmitting elastic sheet material 11, for example, a translucent silicon rubber sheet can be used. The thickness of the elastic sheet material 11 is preferably 1 mm to 2 mm.

  In the present embodiment, as shown in FIG. 2 (a), a plastic grout material 21 that is a first filling material that is non-separable in water and has a low fluidity is filled in the vicinity of the surface S of the crack CR, As shown in 2 (b) (c), a part of the deepest part of the crack CR remaining without being filled with the first filling material is a second filling material that is inseparable in water and has high fluidity. By filling the high fluidity grout material 22, it is possible to fill up to the deepest part of the crack CR, and the filling material can be uniformly injected into the crack CR.

  The first filling material (plastic grout material) needs to have plasticity because it needs self-supporting property to cover the surface of the crack. Plasticity refers to the property of belonging to an intermediate region between a liquid and a solid and having no fluidity of the grout itself, but easily fluidizing when a little pressure is applied. In order to achieve plasticity, a plasticizer is used for a flowable grout mainly composed of a hardening developing material such as cement, and the free water in the grout is made into a water-containing gel to make it plastic. it can. As the plasticizer, water glass aluminum salt, clay minerals such as bentonite, and polymer materials are generally used. As an inseparable plastic grout material, for example, swell bentonite with water and mix it with water, cement, sand and underwater inseparable mortar using admixtures such as underwater inseparators and water reducing agents. Can be used.

  The high fluidity grout material which is the second filling material is a grout having a larger fluidity than the plastic grout material of the first filling material. Here, the measuring method of fluidity is based on the physical test method of JIS R 5201 cement. That is, the ease of flow of the filling material is evaluated as the fluidity. In the case of a material with low fluidity, it does not flow into the deep part of the crack, whereas in the case of a material with high fluidity, it flows into the deep part of the crack.

  According to the test results based on JIS R 5201 of the filling material by the present inventors, in one example of a plastic grout material composed of water, cement, sand, water non-separation agent, water reducing agent, and plasticizer, the flow cone is pulled out. In the example of the high flowability grout material having a non-separability in water as the second filling material, the flow is 235 mm with the flow cone being pulled out, and the flowability is 103 mm. It can be evaluated that the material is more fluid than the plastic grout material. In addition, as a high fluidity grout material, the grout mix (brand name) which is the high fluidity non-shrinkable grout material currently sold from Tokuyama Mtec Co., Ltd. can be used, for example.

  The underwater part crack repairing method according to the present embodiment will be described with reference to FIGS. FIG. 3 is a flowchart for explaining the steps S01 to S09 of the underwater crack repair method according to the present embodiment. FIG. 4 is a partial cross-sectional view schematically showing a state in which the tip of the hand gun is inserted for injection of the first filling material into the cross-shaped cut of the light-transmitting elastic sheet material of FIG.

  Referring to FIG. 3, first, a diver or the like visually inspects the underwater part of the concrete structure (S01), and a crack CR is detected on the surface S of the underwater part C as shown in FIG. 1 (a) (S02). ) If this crack CR is determined to be repaired, the repair process is executed by a diver or the like as follows.

  As shown in FIG. 1B, a light-transmitting elastic sheet material 11 such as silicon rubber having a size covering the crack CR on the surface S of the underwater part C is prepared. It is fixed to the surface S with concrete nails 13 or the like (S03). The elastic sheet material 11 is formed with a plurality of cross-shaped cuts 12a to 12e.

  When the elastic sheet material 11 is fixed (S03), as shown in FIGS. 1B and 1C, in the vicinity of the upper end of the elastic sheet material 11 and in the crack CR for filling with the second filling material described later. The pipe-shaped injection pipe 15 and the drain pipe 16 are set by being inserted into the holes provided in the sheet material 11 so as to extend (S04).

  Next, as shown in FIG. 4, a hand gun type injector 20 is filled with a plastic grout material as a first filling material and formed in a knife shape at the tip of a small-diameter pipe 20b provided on the injection side of the injector 20. Insert the tip 20c into the cross-shaped cut 12a formed at the bottom of the elastic sheet material 11 in FIG. 1B, set the injector 20, and then install it on the rear end side of the injector 20. The plastic grout material inside the injector 20 is sent out by pushing the pushed-in portion 20a toward the tip side, and the plastic grout material (first filling material) is injected into the crack CR shown in FIG. 1C (S05). ).

  The filling material 21 is filled from the lower part of the crack CR by the above-described injection step S05 of the plastic grout material (first filling material), and the surface of the crack CR is passed through the light-transmitting elastic sheet material 11 in the middle of the filling material 21. By visually recognizing the first filling material 21, the filling state on the surface can be easily confirmed.

  The water in the crack CR is discharged to the outside through the other cuts 12b to 12e by the injection of the first filling material 21 into the crack CR.

  The first filling material can be injected by appropriately changing the injection position to the other cuts 12b to 12e. However, the first filling material on the surface of the crack CR is passed through the light-transmitting elastic sheet material 11. By confirming the filling state, the completion of the injection of the first filling material is determined (S06). At this time, since the plastic grout material which is the first filling material 21 has plasticity and relatively low fluidity, it is filled from the surface S to a depth of, for example, 20 mm to 30 mm. That is, the plastic grout material is filled near the surface of the crack CR, as shown in FIG. 2 (a), but does not flow into the deep part of the crack CR, while the part 30 on the deepest part side is in an unfilled state, Demonstrates water-stopping effect due to its self-supporting nature on the surface of cracked CR.

  Next, after the plastic grout material 21 is consolidated, the high fluidity grout material 22 is passed through the flexible hose 15a and the injection tube 15 as shown in FIG. Then, it is injected into the remaining part 30 in an unfilled state (S07).

  Since the high fluidity grout material 22 has higher fluidity than the first filling material, it flows into the deep part in the crack CR and fills the remaining part 30. At this time, the water in the part 30 is discharged to the outside through the drain pipe 16.

  By confirming that the high fluidity grout material 22 has leaked from the drain pipe 16, it can be determined that the remaining part 30 has been sufficiently filled as shown in FIG. Completion is determined (S08).

  Next, post-processing is performed as follows (S09). The injection pipe 15 and the drain pipe 16 are removed, and the first filling material is filled through the holes of the elastic sheet material 11 into the holes formed by the removal. Next, the elastic sheet material 11 is removed, and post-treatment of the surface S filled with the first filling material is performed as necessary.

  As described above, according to the method for repairing a crack in the underwater portion according to the present embodiment, the crack CR on the surface S in the underwater portion is covered with the sheet material 11 fixed to the surface S, and the first portion from the injection portion of the sheet material 11 is covered. Filled with a plastic grout material, which is a filling material, the plastic grout material is relatively small in fluidity, so it does not fill the part 30 on the deepest side of the crack CR, but exhibits a water-stopping effect on the surface of the crack CR To do. Next, since the high fluidity grout material, which is the second filling material having a relatively high fluidity, is injected into the remaining portion 30 through the injection pipe 15 extending into the crack CR, the width of the crack CR is narrowed. However, the high-fluidity grout material can be easily injected into the deepest part, and the high-fluidity grout material can be reliably filled into the remaining part 30. As a result, the first and second filling materials can be evenly distributed. The crack CR can be filled and water can be sufficiently discharged from the crack CR. Further, since the sheet material 11 only needs to be fixed to the surface S of the underwater part with cracked CR, filled with the first filling material, and then filled with the second filling material, it is a simple process. It can repair cracks in the water.

  Further, the water staying in the remaining portion 30 of the crack CR can be discharged to the outside through the drain pipe 16 and removed by the pressure rise accompanying the injection of the high fluidity grout material. In this case, forced drainage may be performed by a pump in order to further improve drainage performance.

  Next, an example in which a plurality of drain pipes are installed in FIGS. 1 and 2 will be described with reference to FIG. FIG. 5 is a vertical cross-sectional view corresponding to FIG. 2A for explaining another example of the underwater crack repairing method according to the present embodiment.

  In the example of FIG. 5, a plurality of drain pipes 16 a to 16 c are arranged apart from each other in the height direction on the elastic sheet material 11 of FIG. 1 and extended into the crack CR. The drain pipe 16 and the drain pipes 16a to 16c are arranged at substantially equal intervals from the lower end to the upper end. When the second filling material is injected into the remaining portion 30 in the crack CR and reaches the height positions of the drain pipes 16a to 16c and 16, as shown in FIG. The second filling material leaks out. By confirming this leakage, the filling position (filling height) of the second filling material in the remaining portion 30 of the crack CR can be confirmed, so that the filling status of the second filling material can be easily grasped. be able to.

  Since the width w of the crack CR in the underwater part (FIG. 1A) is narrow at a predetermined value (for example, 5 mm) or less, the water injection pipe 15 and the drain pipe 16 are close to the surface layer (for example, a part shallower than 40 mm in depth). If it can only be inserted, the water injection pipe 15 and the drain pipe 16 are covered with the plastic grout material, so that the original function is not exhibited even if installed. Therefore, when the width w of the crack CR is smaller than 5 mm, for example, and the water injection pipe 15 and the drain pipe 16 made of pipes cannot be installed in the deep part of the crack CR, as shown in FIG. At the time of injection, a removable filling is arranged on the upper end of the crack CR, and the filling is removed after filling and consolidation of the first filling material 21, for example, an unfilled portion 21 </ b> A composed of a gap of about 2 to 3 cm in height. Is formed at the upper end of the cracked CR. Through this unfilled portion 21A, the high fluidity grout material of the second filling material is injected from the injection tube 15 into the remaining portion 30 of the crack CR. In addition, the water in the crack CR can be discharged from the unfilled portion 21A during the injection. Further, the unfilled portion 21A is closed by filling the first filling material after the filling of the second filling material is completed.

According to the experiments by the present inventors, a plastic non-separable grout (plastic grout) is injected into a crack with a surface opening width of 5 mm using the sheet material of FIG. However, in the deep part where the crack depth was 40 mm or more, no pressure was applied and the fluidity was small, and the filling was insufficient. The plastic grout used is composed of 0.48 kg of water, 2.0 kg of powder (cement, sand, water non-separation agent, water reducing agent), and 0.04 kg of plasticizer (bentonite). Next, as shown in FIGS. 1 and 2, the above-mentioned plastic grout is injected and filled to a depth of 20 to 30 mm from the surface of the crack, and after consolidation, the high fluidity grout is put into the remaining crack in the crack. When injected into a part, the high fluidity grout did not leak from the surface of the crack and was injected deep into the crack. In addition, it is confirmed that the plastic grout after filling exhibits a strength equal to or higher than that of the base material (base material compressive strength: 30.3 N / mm ² ). I never did.

  In addition, it is possible to inject the high fluidity grout into the crack without using plastic grout and stop the surface layer with a putty to prevent leakage of the high fluidity grout, but the putty is inserted into the crack. It is difficult to do and stays in the vicinity of the crack surface. In that case, when a high fluid grout is injected under pressure, a putty with a thickness as thin as about 10 mm at the maximum is weak in adhesion and there is a possibility that a sufficient water stop effect cannot be expected. In this way, when using a high fluidity grout from the beginning without using a plastic grout, it is necessary to take measures to prevent the leakage of the injected material, and implement a leakage prevention measure so that there is no slight gap. There is a need to. On the other hand, as in the present embodiment, by filling the surface of the crack with the plastic grout, not only filling but also a water stop effect can be obtained, and a special high-fluid grout leakage prevention measure is unnecessary.

  As described above, the modes for carrying out the present invention have been described. However, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, in the present embodiment, cracks extending in the substantially vertical direction in the underwater portion are taken as an example, but the present invention is not limited to this, and repairing cracks extending in the horizontal direction, inclined cracks, and cracks with a bend. Of course, it can be targeted. Moreover, although the injection tube 15 was installed in the upper part (one end side) of crack CR in FIG.1, FIG.2, FIG.5, of course, you may install in the lower part (other end side).

  Further, the shape of the cut formed in the elastic sheet material 11 as the injection portion and the drainage portion is preferably a cross shape formed of two lines, but is not limited to this in the present invention. For example, a horizontal line shape “−” formed of a single line ”, A vertical line shape“ | ”, a diagonal line shape“ / ”, or a triple line shape where three lines intersect at the center.

  Further, as the light-transmitting elastic sheet material, a translucent silicon rubber sheet is used in the present embodiment and experimental examples, but the present invention is not limited to this. For example, transparent or translucent vinyl chloride or urethane is used. A rubber sheet or the like may be used. Further, the elastic sheet material needs to be light transmissive, but it is sufficient if the filling state of the filling material in the crack is visible in water.

  In addition, concrete structures to which the repair method according to the present invention is applied include revetments, quay walls, and dams, but are not limited thereto, and at least a part of the concrete structure has an underwater part in contact with water. Applicable.

  According to the method of repairing a crack in an underwater part of the present invention, a filling material can be uniformly filled in a crack in the underwater part of a concrete structure with a simple process, so that the crack in the underwater part can be repaired reliably and with a simple process. it can.

11 sheet material, elastic sheet material 12a-12f cut (injection part, drainage part)
15 Injection pipe 16, 16a-16c Drain pipe 21 1st filling material, plastic grout material 21A Unfilled part 22 2nd filling material, high fluidity grout material 30 Part C of deepest part of crack C Underwater part CR Crack

Claims (6)

A method of repairing a crack in the underwater part of a concrete structure,
A sheet material made of an elastic material is fixed on the surface of the underwater part with cracks so as to cover the cracks,
By injecting the first non-separable first filling material through the injecting portion of the sheet material, the first filling material is filled in the crack leaving a part on the deepest side of the crack,
A method for repairing a crack in an underwater part, wherein a second filling material that is inseparable in water and has a higher fluidity than the first filling material is injected into the part through an injection tube extending into the crack.   2. The submersible part according to claim 1, wherein a drain pipe for discharging the water in the part to the outside during the filling of the second filling material is installed before filling the first filling material through the sheet material. Crack repair method. A plurality of the drain pipes are installed apart in the extension direction of the crack,
The filling position of the second filling material in the part is confirmed by confirming leakage of the second filling material from the drain pipes when filling the second filling material. How to repair cracks in the water. Forming an unfilled portion not filled with the first filling material at one end of the crack when filling the first filling material;
The method for repairing a crack in an underwater part according to any one of claims 1 to 3, wherein the second filling material is injected into the part through the unfilled part. The sheet material is composed of a light transmissive material,
The method for repairing a crack in an underwater part according to any one of claims 1 to 4, wherein a filling state of the first filling material is confirmed through the light-transmitting sheet material.   The method for repairing a crack in an underwater part according to any one of claims 1 to 5, wherein at least two injection parts are provided in the sheet material.

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