JP6478834B2 - How to prevent flaking of concrete pieces - Google Patents

Description

  The present invention relates to a method for preventing a concrete piece from peeling off from a concrete frame such as a bridge or a tunnel, or for preventing a concrete piece that is about to fall off.

  This type of concrete flaking prevention method includes a method in which a grid-like FRP net is fixed to a concrete surface with an anchor pin (Patent Document 1), and a net-like material is interposed between the FRP lattice and the concrete surface. A method of fixing with an anchor bolt (Patent Document 2) is known.

  The FRP net described in Patent Document 1 describes a method in which a grid interval is 50 mm, a 60 mm square seat plate is placed on the net, and anchor pins are driven into a concrete surface to be fixed.

  In Patent Document 2, the FRP lattice is formed and hardened in a lattice plate shape with an interstitial distance of 30 to 150 mm, and only this lattice is fixed with an anchor bolt, and between this lattice and the concrete surface. A method of fixing with an anchor bolt with a mesh of about 1 mm to 25 mm interposed is described. And when a net-like object is piled up on a lattice line, the fall of a small concrete piece is prevented with a mesh object, and the big concrete piece is prevented with a lattice line.

JP 2009-256881 A JP 2006-9266 A

  The ones shown in Patent Documents 1 and 2 are FRPs having both lattice nets and lattice streaks that are hard, so that it is possible to reliably prevent falling heavy heavy concrete pieces, but the concrete surface is bent or curved. Then, the lattice net and the lattice line must be manufactured in advance in a shape that matches the deformation surface. In addition, in order to avoid obstacles such as protrusions and drain pipes, it is necessary to perform extremely troublesome processing such as cutting a part.

  In addition, long concrete such as bridges have two concrete plates connected at the joints to avoid misalignment due to expansion and contraction. Cracks in the concrete surface close to the joints are likely to occur. When covering with a hard lattice net, the two concretes move in different directions due to vehicle traffic or seismic motion, causing unnecessary force on the anchor bolts to come off, and the holding power to weaken. was there.

  The present invention is intended to provide a method for preventing peeling using a fall prevention net that is bendable, can be cut with a normal scissors, and has sufficient strength against peeling.

According to the method for preventing flaking of a concrete piece according to the present invention, a fall prevention net 12 is adhered to the surface of a concrete case 10 with a plurality of anchor pins 13 to prevent the fall of the concrete piece peeled off from the concrete case 10. In the method of preventing flaking of concrete pieces,
The fall prevention net 12 is made by braiding a high-strength vinylon fiber and a fiber having alkali resistance and flame resistance, which is coated with a vinyl chloride resin, and can be bent and cut with a normal scissors. It is characterized by that.

The warp and weft constituting the fall prevention net 12 are two twisted yarns in which fibers having a diameter of 430 to 440 μm are aligned so as to be 2000 dtex, and two twisted yarns of these 4000 dtex are further twisted, and these 8000 dtex. It is characterized in that warp yarns and weft yarns made of twisted yarns of about 0.8 mm in diameter are knitted with mesh yarn.

When adhering the fall prevention net 12 to the concrete housing 10, the peripheral edge of the fall prevention net 12 is temporarily attached with a double-sided tape and fixed with anchor pins 13 at predetermined intervals.
When adhering the fall prevention net 12 to the concrete housing 10, the edge net 29 is overlapped on the peripheral edge of the fall prevention net 12 and fixed by the anchor pin 13.

  In order to avoid the obstacle 31 in the concrete housing 10, a part of the fall prevention net 12 is excised with a scissors, an auxiliary net 30 is applied to the peripheral edge of the excised portion, and the anchor pin 13 is fixed to the concrete housing 10.

  When stricter conditions such as in a tunnel are required, an auxiliary frame that is assembled between the fall prevention net 12 and the concrete housing 10 at a larger interval than the mesh of the fall prevention net 12 and has flexibility. 35 is attached, and the fall prevention net 12 and the auxiliary frame 35 are fixed to the concrete frame 10 with the anchor pins 13.

In the method for preventing concrete pieces from being dropped, the fall prevention net is adhered to the surface of the concrete body with a plurality of anchor pins, and the concrete pieces removed from the concrete body are prevented from falling.
The fall prevention nets, alkali resistance coated with vinyl chloride resin to bi Nilon fiber, there is braided fibers having flame resistant, bendable, Ri Do from those cleavable by ordinary scissors,
The warp and weft constituting the fall prevention net are two twisted yarns in which fibers having a diameter of 430 to 440 μm are aligned so as to be 2000 dtex, and two twisted yarns of these 4000 dtex are further twisted, and these 8000 dtex Knitting warp and weft yarns of about 0.8mm in diameter made of twisted yarn with mesh yarn,
In order to avoid obstacles in the concrete frame, a part of the fall prevention net is excised with scissors, an auxiliary net is applied to the peripheral part of the excised part, and the anchor pin is fixed to the concrete frame,
Assembled between the fall prevention net and the concrete frame at intervals larger than the mesh of the fall prevention net, and an auxiliary frame having flexibility is applied, and the fall prevention net and the auxiliary frame are connected to the concrete frame with anchor pins. Since it adheres to, it has the following effects.
(1) It is possible to prevent the concrete pieces from falling off only by the fall prevention net. In addition, even if there are obstacles such as protrusions on the concrete frame, the fall prevention net can be easily removed by cutting it with a normal rod. In addition, water drops and heat do not accumulate between the net and the concrete surface, and concrete deterioration due to free lime can be prevented. Furthermore, it is possible to visually inspect cracks on the concrete surface and perform infrared inspection. Furthermore, it does not unnecessarily stress the two concrete frames connected at the joint.
(2) A thin, light and strong net can be obtained. Moreover, there is no damage of the net by a hammering test.
(3) Even if a part of the fall prevention net is cut out or cut, the strength of the fall prevention net 12 does not drop.
(4) It is effective when a tunnel is required to be particularly strong and curved.

According to the second aspect of the present invention, since the mesh interval in the fall prevention net is smaller than the diameter of the aggregate of the concrete frame and larger than the diameter of the anchor pin, the concrete is peeled off, and the falling stone passes through the net. However, the human body and the vehicle are hardly damaged.

According to the third aspect of the present invention, when attaching the fall prevention net to the concrete frame, the peripheral edge of the fall prevention net is temporarily attached with a double-sided tape and fixed with an anchor pin at a predetermined interval. Can be smoothly applied

According to the fourth aspect of the present invention, when attaching the fall prevention net to the concrete frame, the edge net is overlapped on the peripheral edge of the fall prevention net and fixed with the anchor pin, so the load of the peeled concrete piece is applied. However, fraying of the edge of the fall prevention net can be prevented.

According to the invention described in claim 5 , the anchor pin includes a plate-shaped seat plate that is sufficiently larger than the mesh of the fall prevention net, a washer that fits into a recess in the center of the seat plate, and the anchor pin and the seat plate. It consists of an anchor pipe having a flange portion inserted into a substantially central insertion hole and an expansion plug driven into the anchor pipe, and the concave and convex grooves at the tip end portion of the anchor pipe are bulged by driving the expansion plug. In this way, the anchor pin is pressed into and fixed to the prepared hole drilled in the concrete casing, and the filler is injected into the prepared hole after the fixing, so that the deterioration of the anchor pin over time can be prevented.

It is sectional drawing of the state which attached the fall prevention net | network 12 with the anchor pin 13 to the concrete frame 10 for demonstrating the peeling prevention method of the concrete piece by this invention. It is sectional drawing explaining the peeling prevention method of the concrete piece by this invention which attached the fall prevention net | network 12 between the two concrete frames 10 connected with the joint part 11. FIG. (A) is a front view of the state in which the seat plate 14 and the anchor pin 13 are attached to the fall prevention net 12, and (b) is the seat plate 14 and the anchor pin 13 with the edge net 29 superimposed on the fall prevention net 12. It is a front view of the attached state. (A) is sectional drawing of the state which attached the fall prevention net 12 from the side surface of the bridge 33 to the lower surface, (b) is a bottom view of (a). It is sectional drawing of the state which is constructing the peeling prevention method of the concrete piece of this invention in a tunnel. It is a front view which shows an example of the fall prevention net | network 12 used for a tunnel. (A) is the one part enlarged front view of FIG. 6, (b) is a sectional side view of (a). (A) is a front view which shows a drawing test, (b) is a top view which shows a drawing test. It is a characteristic view which shows the relationship between the elongation X and the load Y in a drawing test.

  The present invention relates to a method for preventing a concrete piece from falling off, in which a fall prevention net 12 is attached to the surface of a concrete case 10 with a plurality of anchor pins 13 to prevent the fall of the concrete piece peeled off from the concrete case 10. The fall prevention net 12 is made by braiding a high-strength vinylon fiber and a fiber having alkali resistance and flame resistance, which is coated with a vinyl chloride resin, and can be bent and cut with a normal scissors. Used.

Specifically, the fall prevention net 12 is composed of two warps and wefts obtained by twisting two 430-440 μm fibers aligned so as to be 2000 dtex, and two twisted yarns of 4000 dtex further twisted. These warps and wefts having a diameter of about 0.8 mm made of these 8000 dtex twist yarns are knitted with a mesh yarn.
Further, the mesh interval in the fall prevention net 12 is smaller than the diameter of the aggregate of the concrete frame 10 and larger than the diameter of the anchor pin 13.

  When adhering the fall prevention net 12 to the concrete housing 10, the peripheral edge of the fall prevention net 12 is temporarily attached with a double-sided tape and fixed with anchor pins 13 at predetermined intervals.

  When sticking the fall prevention net 12 to the concrete housing 10, an edge net 29 is overlapped on the peripheral edge of the fall prevention net 12 and fixed by the anchor pin 13.

  When a part of the fall prevention net 12 is cut off with a scissors or a cut is made in order to avoid the obstacle 31 in the concrete casing 10, an auxiliary net 30 is applied to the peripheral portion of the cut part, and the anchor pin 13 is fixed to the concrete housing 10.

  In tunnel construction or the like, an auxiliary frame 35 that is assembled between the fall prevention net 12 and the concrete frame 10 at a larger interval than the mesh of the fall prevention net 12 and has flexibility is assigned. And the auxiliary frame 35 are fixed to the concrete frame 10 with the anchor pins 13 to prevent the concrete pieces from peeling off.

Example 1 of a concrete stripping prevention method according to the present invention will be described with reference to the drawings.
FIG. 2 shows a structure, such as a bridge, in which two long concrete frames 10 are connected by joints 11 between them, and straddles the surface of the two concrete frames 10 sandwiching the joints 11. An example in which the fall prevention net 12 is stretched and fixed with anchor pins 13 is shown.

  The fall prevention net 12 is bendable, can be cut with a normal scissors, and has sufficient strength against peeling, alkali resistance, and flame resistance. Specifically, a high-strength vinylon fiber is coated with a vinyl chloride resin. Fibers having a diameter of 430 to 440 μm are aligned so as to be 2000 dtex (2000 g per 10,000 m), and these 2000 dtex are used as a twisted yarn to make 4000 dtex. The two pieces of 4000 dtex are aligned, knitted with a 300 d knitting yarn, and these are woven as warps and wefts each having a diameter of about 0.8 mm.

When the fall prevention net 12 is plain weave, the mesh interval d is smaller than the diameter of the aggregate (usually 13 mm) kneaded into the concrete housing 10 as shown in FIG. It is preferable to make it larger than the diameter (usually 4.5 or 6 mm). In this example, d = 8.0 mm × 8.0 mm. The fall prevention net 12 is not limited to a plain weave, and may be a twill or other known weaving method.

  Anchor pins 13 are used to fix the fall prevention net 12 to the surface of the concrete housing 10. The anchor pin 13 includes an anchor pipe 16, a seat plate 14, an expansion plug 22, and a washer 25. The anchor pipe 16 is made of a stainless steel pipe having an outer diameter of 4.5 or 6.0 mm and a length of about 45 to 100 mm, and a flange portion 17 that is open to the outside is formed at the base end portion. Are formed with concave and convex grooves 18 composed of inner ridges 19 and outer ridges 20 in the circumferential direction at intervals of about 5 mm, and 2 to 4 slits 21 are formed in the length direction. Yes. The expansion plug 22 has a cylindrical shape that can be inserted while being substantially in contact with the inside of the anchor pipe 16, and a tapered portion 23 is formed at the tip.

  The seat plate 14 is an FRP square plate having a width of about 50 to 100 mm (60 mm in the embodiment), and a recess 26 into which a washer 25 is fitted in the center, and the anchor pipe 16 penetrates through the center of the recess 26. An insertion hole 27 is formed, and a protruding edge bulges on the back surface of the insertion hole 27 as necessary.

An operation process for attaching the fall prevention net 12 to the surface of the concrete frame 10 using the fall prevention net 12 and the anchor pin 13 as described above will be described.
As shown in FIG. 2, when two concrete frames 10 are continuous with the joint portion 11 interposed therebetween, the corner cracks 15 are likely to occur at the continuous edge portion, so both sides sandwiching the joint portion 11. It is preferable to stick the fall-preventing net 12 that is continuous with the above.
Therefore, as a preparatory work, a fall prevention net 12 knitted to a width of 2.1 m and a length of 50.0 m and wound into a roll is prepared and cut into a width of 2.1 m and a length of 4.1 m.
The edge part of the cut fall prevention net 12 is temporarily fixed to the surface of the concrete case 10 with a double-sided adhesive tape having a width of 3 to 10 mm.
For example, 1000 mm, 600 mm, 500 mm, 250 mm, and the like are drilled in the concrete casing 10 with a drill hole 24 in the end edge portion of the fall-preventing net 12 temporarily fixed. At this time, the pilot hole 24 is carefully drilled so as not to cut the fiber at the center of the mesh of the fall prevention net 12. The depth of the pilot hole 24 is adjusted to the length of the anchor pin 13.

The insertion hole 27 of the seat plate 14 is placed on the fall prevention net 12 so as to coincide with the lower hole 24, the washer 25 is fitted into the recess 26 of the seat plate 14, and the anchor pipe 16 is inserted. Next, the expansion plug 22 is inserted into the anchor pipe 16 so that the tapered portion 23 is at the tip. After inserting the expansion plug 22, when the driving rod is inserted into the anchor pipe 16 and the expansion plug 22 is driven with a hammer, the inner protrusion 19 of the concave and convex groove 18 is pushed outward by the expansion plug 22, The outer ridge 20 is pressed against the inner wall of the pilot hole 24 to prevent the anchor pin 13 from coming off.
When the anchor pin 13 is fixed to the concrete housing 10 and the filler 28 is press-fitted into the anchor pipe 16 with a resin injection gun, the filler 28 passes through the slot 21 from the inside of the anchor pipe 16 and the anchor pipe 16 and the pilot hole. The air also flows into the gap 24 and is flattened at the flange portion 17 to finish driving the anchor pin 13.
Similarly, the anchor pins 13 are driven at predetermined intervals, and the fall prevention net 12 is adhered to the surface of the concrete frame 10.

Next, the case where it installs in the bridge 33 is demonstrated.
Since the construction position of the bridge 33 differs depending on whether it is the traveling side, the overtaking side, the shape, or the presence of an obstacle, it is necessary to process the fall prevention net 12 according to different positions.
For example, as shown in FIG. 4A, a case where the lower surface is protected from the side surface of the sound insulation wall of the traveling lane of the bridge 33 and the obstacle 31 such as a water pipe protrudes from the lower surface will be described.
In this case, the vertical surface portion is 800 mm, the lower surface portion is 1200 mm, and the entire width is cut to 2000 mm. The length is 4.1 m. The reason why the length is set to 10 cm instead of 4.0 m is to make the overlapping portion 10 cm when continuous in the length direction.

In the fall prevention net 12 cut in this way, when there are obstacles such as an obstacle 31 such as a water pipe, a circular and straight cut 32 is cut with a normal scissors as shown in FIG. Process it. An auxiliary net 30 is put on the straight cut 32.
The fall prevention net 12 processed in this way is temporarily fixed with a double-sided tape.
After temporary fixing, the edge of the fall prevention net 12 is fixed at a predetermined interval by the method shown in FIG. Specifically, the distance in the length direction of the fall prevention net 12 is 1000 mm, and the distance in the width direction is one at the upper end of the vertical surface, one at the corner of the lower surface, and 1 at the edge of the lower surface. Individual.
The anchor pin 13 is driven and fixed as finely as possible to the portion of the notch 32 cut out to avoid the obstacle 31 such as the water pipe and the portion covered with the auxiliary net 30.

When the anchor pin 13 is driven, a seat plate 14 is directly attached to the fall prevention net 12 and fixed by the anchor pin 13 as shown in FIG. Further, in a place where a relatively large load is expected to be applied, as shown in FIG. 3 (b), a fine edge net 29 having a mesh width of about 10 cm is overlapped on the end edge of the fall prevention net 12 and anchored. It is desirable to fix with the pin 13.
After the anchor pin 13 is driven, the filler 28 is press-fitted into the anchor pipe 16 with a resin injection gun as in FIG.

  Next, when the standard of the maximum load of the fall prevention net 12 is higher than the standard of peeling of the surface of the general concrete frame 10, such as the inner wall of the tunnel 34, the direction perpendicular to the length direction of the tunnel 34 For example, a narrow fall prevention net 12 having a width of 600 × 2000 mm is used. In order to fix the fall prevention net 12, it is conceivable that the distance between the anchor pins 13 is reduced to 500 mm, 350 mm, 250 mm, etc. However, as shown in FIGS. A frame 35 is inserted. The auxiliary frame 35 is formed of a bendable FRP thin plate having a width of 20 to 30 mm, a thickness of 5 to 15 mm, an end edge interval of 50 to 150 mm, and a central portion of 400 to 500 mm.

  By using such an auxiliary frame 35 and the fall prevention net 12, as shown in FIG. 5, it can be attached in close contact with the curved wall surface, and when there is a large peeling, The fall can be reliably prevented.

A pull-out test of the fall prevention net 12 used in the present invention will be described.
8A and 8B, a circular loading plate 38 having a diameter of 100 mm is placed at the center of the stationary platen 37, and the fall prevention net 12 as a test piece having a width of 600 mm and a length of 650 mm is placed on the loading plate 38. Cover. A shaft 40 connected to the center of the load plate 38 is projected from the mesh at the center position of the fall prevention net 12. This shaft 40 is connected to a drawing machine 39. The fall prevention net 12 is fixed to the fixed plate 37 with anchor pins 13 at six places with a pitch of 500 mm in the width direction and a pitch of 250 mm in the length direction.

In this state, the loading plate 38 is pulled out at a speed of 20 mm / min by the puller 39. Then, the elongation X of the fall prevention net 12 and the load Y applied to the loading plate 38 change in a substantially direct proportion and are broken at the predetermined load Y.
A waveform when the same test is repeated three times is shown in FIG. This was expressed as follows.
Specimen No. Maximum load Y (kN) Maximum elongation X (mm)
1 1.981 238.65
2 2.064 249.41
3 2.334 267.46
Average value 2.126 251.84
The standard fall prevention net 12 is required to have a maximum load Y = 1.2 kN or more. The fall prevention net 12 of the tunnel 34 is required to have a maximum load Y = 1.5 kN or more. According to this, sufficient values were obtained in either case.

  DESCRIPTION OF SYMBOLS 10 ... Concrete frame, 11 ... Joint part, 12 ... Fall prevention net, 13 ... Anchor pin, 14 ... Seat plate, 15 ... Crack, 16 ... Anchor pipe, 17 ... Collar part, 18 ... Concave groove, 19 ... Inward projection , 20 ... outer protrusion, 21 ... slit, 22 ... expansion plug, 23 ... tapered portion, 24 ... pilot hole, 25 ... washer, 26 ... depression, 27 ... insertion hole, 28 ... filler, 29 ... Edge net, 30 ... auxiliary net, 31 ... obstacle such as water pipe, 32 ... notch, 33 ... bridge, 34 ... tunnel, 35 ... auxiliary frame, 36 ... work vehicle, 37 ... fixed plate, 38 ... loading plate, 39 ... drawer, 40 ... shaft.

Claims (5)

In the method for preventing concrete pieces from being dropped, the fall prevention net is adhered to the surface of the concrete body with a plurality of anchor pins, and the concrete pieces removed from the concrete body are prevented from falling.
The fall prevention nets, alkali resistance coated with vinyl chloride resin to bi Nilon fiber, there is braided fibers having flame resistant, bendable, Ri Do from those cleavable by ordinary scissors,
The warp and weft constituting the fall prevention net are two twisted yarns in which fibers having a diameter of 430 to 440 μm are aligned so as to be 2000 dtex, and two twisted yarns of these 4000 dtex are further twisted, and these 8000 dtex Knitting warp and weft yarns of about 0.8mm in diameter made of twisted yarn with mesh yarn,
In order to avoid obstacles in the concrete frame, a part of the fall prevention net is excised with scissors, an auxiliary net is applied to the peripheral part of the excised part, and the anchor pin is fixed to the concrete frame,
Assembled between the fall prevention net and the concrete frame at intervals larger than the mesh of the fall prevention net, and an auxiliary frame having flexibility is applied, and the fall prevention net and the auxiliary frame are connected to the concrete frame with anchor pins. A method for preventing delamination of concrete pieces, characterized in that it adheres to the surface. Spacing of the mesh in the fall prevention nets is smaller than the diameter of the aggregate of the concrete skeleton, spalling prevention method according to claim 1 concrete piece, wherein it has greater than a diameter of the anchor pin. 3. The concrete piece according to claim 1 or 2 , wherein when the fall prevention net is stuck to the concrete frame, the peripheral edge of the fall prevention net is temporarily stuck with a double-sided tape and fixed with an anchor pin at a predetermined interval. How to prevent flaking. 4. The method for preventing flaking of a concrete piece according to 1, 2 or 3 , wherein, when the fall-preventing net is adhered to the concrete frame, an edge net is overlapped on the peripheral edge of the fall-preventing net and fixed with an anchor pin. The anchor pin consists of a plate-shaped seat plate that is sufficiently larger than the mesh of the fall prevention net, a washer that fits into a recess in the center of the seat plate, and a flange that is inserted into the insertion hole in the center of the anchor pin and the seat plate. And an expanded plug that is driven into the anchor pipe, and a pilot hole that is formed in the concrete frame by expanding the concave and convex grooves at the tip of the anchor pipe by driving the expanded plug. flaking method of preventing pressure sticking to claim 1, 2, 3 or 4 concrete element according to characterized by comprising injecting a filler material into the prepared hole after sticking to.

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