Repair method for existing sprayed slopes

Abstract

To provide a repair method for an existing sprayed slope that can suppress the generation of a large amount of industrial waste and shorten the construction period without the need to install a large-scale temporary protective wall, and can reduce the possibility of re-construction even if damage such as peeling / collapse or cracking of the spray surface due to deterioration or aging due to weathering, or due to natural disasters occurs.SOLUTION: A repair method for an existing sprayed slope comprises: a cleaning step S20 for cleaning the damaged existing sprayed slope; a spraying step S30 for constructing a sprayed slope by spraying an adhesive mortar on the existing sprayed slope after cleaning; a placing step S40 for placing reinforcing bars at predetermined locations on the sprayed slope; and a lining step S50 for covering a surface of the sprayed slope with a wire mesh body via the placed reinforcing bar, and then, holding the wire mesh body with a wire rope.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a repair method for an existing sprayed slope constructed by spraying mortar, concrete, etc. (hereinafter referred to as an existing sprayed slope) that has deteriorated or been damaged due to weathering, natural disasters, etc. [Background technology]

[0002] The shotcrete method is used to construct a shotcrete slope by spraying mortar or concrete on the slope of a mountainside after laying and fixing wire mesh or frames on the slope as part of measures against natural disasters such as weathering, heavy rain, or landslides. However, existing shotcrete slopes constructed using this method may suffer damage such as peeling, collapse, or cracks on the sprayed surface due to deterioration or aging caused by weathering or natural disasters about 10 to 20 years after construction. In such cases, repair work is required for the existing shotcrete slope, but in the past, it was common to peel off the damaged existing shotcrete slope by hand or machine, reshape it after peeling, and then reapply the mortar or concrete.

[0003] However, the above repair method requires the installation of a large-scale temporary protective wall to safely remove the existing sprayed slope. In addition, there are many problems with this method, such as the generation of a large amount of industrial waste during the removal process and the risk of the sprayed surface collapsing during the removal process, threatening the safety of workers and third parties.

[0004] In order to solve the above problems, for example, Patent Document 1 describes a restoration method for aging mortar sprayed slopes that minimizes industrial waste, is an inexpensive method, minimizes traffic restrictions, and sufficiently ensures the stabilization of the slopes. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-24440 A Summary of the Invention [Problem to be solved by the invention]

[0006] The restoration method for aging mortar-sprayed slopes described in Patent Document 1 includes a step of removing mortar from one or more sections including the lowest end of the mortar-sprayed slope or one or more sections located at an intermediate height, and a step of constructing a permeable concrete reinforcement body by spraying permeable concrete onto the sections from which the mortar has been removed. The restoration method described in Patent Document 1 can reduce the amount of industrial waste discharged by limiting the number of sections from which mortar is removed, but in addition to limiting the positions of the mortar to be removed, the sprayed concrete reinforcement body will eventually suffer damage such as peeling and collapse of the sprayed surface or cracks due to deterioration or aging caused by weathering or natural disasters, and in this case, the restoration method must be applied again.

[0007] The present invention has been made in consideration of these circumstances, and provides a repair method for existing sprayed slopes which makes it possible to reduce the generation of large amounts of industrial waste and shorten the construction period without requiring the installation of large-scale temporary protective walls, and which reduces the possibility of re-construction even if damage such as peeling, collapse, or cracks of the sprayed surface occurs due to deterioration or aging caused by weathering or a natural disaster. [Means for solving the problem]

[0008] In order to solve the above problems, the repair method for an existing sprayed slope according to the present invention includes a cleaning step of cleaning the damaged existing sprayed slope, a spraying step of constructing a sprayed slope by spraying an adhesive mortar containing an admixture containing carbon fiber onto the existing sprayed slope after cleaning, a casting step of drilling holes at predetermined intervals on the sprayed slope so as to form a grid of approximately equal intervals when viewed from the front, and casting reinforcing bars with heads protruding from the surface of the sprayed slope into each hole leading to the natural ground, and a casting step of applying pressure to the surface of the sprayed slope through the cast reinforcing bars. Flat Line After covering it with a wire mesh, the wire rope is used to secure the Flat Lineand a covering process for holding the wire mesh body. The adhesive mortar has a tensile adhesive strength of 0.88 N / mm according to JIS A 1171. 2 The adhesive is characterized by having a tensile adhesive strength of at least 100 MPa.

[0009] Furthermore, the repair method for existing sprayed slopes according to the present invention is characterized in that tension members are provided on the reinforcing bars exposed from the surface of the sprayed slope, and the wire mesh body laid on the surface of the sprayed slope is held in place by wire ropes that are hung in a zigzag pattern between the tension members of the reinforcing bars.

[0010] Furthermore, the repair method for an existing sprayed slope according to the present invention is characterized in that an admixture containing carbon fiber is mixed into the adhesive mortar.

[0011] Furthermore, in the above-mentioned repair method for an existing sprayed slope according to the present invention, the wire mesh body is a flat wire mesh.

[0012] Furthermore, in the above-mentioned repair method for an existing sprayed slope according to the present invention, the casting process for casting reinforcing bars at predetermined locations on the sprayed slope is characterized in that the reinforcing bars are cast in square positions that are approximately equally spaced when viewed from the front on the sprayed slope, and the auxiliary bars are cast at intervals of 3.0 to 1.0 m, preferably 2.5 to 1.5 m. Effect of the Invention

[0013] According to the present invention, it is possible to provide a repair method for existing sprayed slopes that makes it possible to reduce the generation of large amounts of industrial waste and shorten the construction period without requiring the installation of large-scale temporary protective walls, and that reduces the possibility of re-construction even if damage such as peeling, collapse, or cracks of the sprayed surface occurs due to deterioration or aging caused by weathering or a natural disaster. [Brief description of the drawings]

[0014] [Figure 1]1 is a flowchart illustrating an example of a construction flow of a repair method according to the present embodiment. [Diagram 2] These are the results of testing the effect of adding a special admixture containing liquid microcarbon fiber to adhesive mortar. [Diagram 3] FIG. 2 is an explanatory diagram for illustrating a schematic diagram of the spraying process in step S30 of the repair method according to the present embodiment. [Figure 4] FIG. 2 is an explanatory diagram that illustrates the pouring process in step S40 of the repair method according to this embodiment. [Diagram 5] 13 is a diagram illustrating the state in which the surface of a sprayed slope 50 is covered with a wire mesh 70 via auxiliary reinforcing bars 60 cast into the sprayed slope 50. FIG. [Figure 6] 13 is a diagram illustrating a state in which a wire mesh body 70 is held by a wire rope 80. FIG. [Figure 7] 11 is a diagram illustrating the procedure for installing a tension member 90 for suspending a wire rope 80 across the auxiliary reinforcing bar 60 cast in step S40 of the repair method according to this embodiment. FIG. [Figure 8] 13 is a diagram illustrating a method of securing the entire wire mesh body 70 laid on the surface of a sprayed slope 50 with a wire rope 80. FIG. [Figure 9] 1A to 1C are diagrams illustrating an example of a method for suspending a wire rope 80 over a tension member 90. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following description, and can be modified as appropriate without departing from the gist of the present invention.

[0016] FIG. 1 is a flow chart for explaining an example of the construction flow of the repair method according to this embodiment. In the repair method according to this embodiment, a cleaning step S20, a spraying step S30, a casting step S40, and a covering step S50 are sequentially performed on a damaged existing sprayed slope. If necessary, a pre-processing step such as removing overgrown vegetation and already collapsed slope pieces and laying a simple protective sheet may be provided as a pre-processing step (step S10) of the cleaning step S20. Also, a post-processing step such as removing the protective sheet laid in the pre-processing step S10 may be provided as a post-processing step (step S60) of the covering step S50.

[0017] The cleaning process in step S20 is a process of cleaning the surface of the existing sprayed slope, which is the slope to be repaired, by spraying high-pressure water using a high-pressure washer or high-pressure pump. In this case, additives such as solvents and detergents may be added to the cleaning water to be sprayed, and there is no limit to the additives to be added as long as the adhesive mortar to be sprayed in the spraying process in step S30 can be reliably adhered. In addition to removing dirt adhering to the surface of the damaged existing sprayed slope, this cleaning process may also peel off areas (portions) that have become weak due to damage with high-pressure cleaning water.

[0018] The spraying process in step S30 is a process of constructing a sprayed slope by spraying an adhesive mortar, the mixture ratio of cement and sand of which is adjusted to approximately 1:4, onto the existing sprayed slope. As a result of extensive research by the applicant into adhesive mortar to be sprayed onto the existing sprayed slope, the applicant has found that, compared to spraying with ordinary adhesive mortar, adding a special admixture containing liquid microcarbon fiber and spraying it enhances the adhesive effect with the existing sprayed slope, and makes it possible to integrate the existing sprayed slope with cracks.

[0019] Here, Figure 2 shows the results of a test on the effect of adding a special admixture containing liquid microcarbon fiber to adhesive mortar. Specifically, three sprayed mortar specimens (4cm x 4cm x 1cm) were prepared by spraying normal adhesive mortar and adhesive mortar containing the special admixture, and after curing for 28 days, they were subjected to a peel tester to measure the tensile bond strength. This test was conducted in accordance with JIS A 1171, and the tensile bond strength was calculated from the readings from the tester (tensile bond strength (N / mm 2 )=((reading value (kN) × 1000) / 1600)).

[0020] As shown in Figure 2, when sprayed with normal adhesive mortar, the tensile bond strength of the three sprayed mortar specimens was 0.81 N / mm 2 , 0.75N / mm 2 , 0.50N / mm 2 The average tensile bond strength is 0.69 N / mm 2 In contrast, when sprayed with adhesive mortar containing a special admixture, the tensile bond strength of the three sprayed mortar specimens was 1.06 N / mm 2 , 1.00N / mm 2 , 0.88N / mm 2 The average tensile bond strength is 0.98N / mm 2 From these results, it became clear that the adhesive mortar to which the special admixture was added had a tensile adhesive effect that was about 1.4 times that of the normal adhesive mortar. Therefore, in the spraying process of step S30, the special admixture containing liquid microcarbon fiber was applied to mortar adjusted to a cement to sand ratio of about 1:4, and 1 m of the mortar was sprayed with the special admixture. 3 It was decided to add approximately 250g of this to the concrete to be used as adhesive mortar.

[0021] FIG. 3 is an explanatory diagram for explaining the spraying process of step S30. For example, when a slope 10 to be repaired is an area formed on a slope of a mountainside and shown in a long and narrow trapezoid shape having a damaged portion d on its surface, in the spraying process of step S30, an adhesive mortar 40 containing a special admixture is sprayed onto the existing sprayed slope 20 using a spray hose 30 connected to a high-pressure pump or the like (not shown), forming a sprayed slope 50 with a layer thickness of about 2 cm to 5 cm, preferably 3 cm to 4 cm. By adding a special admixture containing liquid microcarbon fiber to the mortar, the fibers are entangled with the cement particles in a state of close contact with each other, blocking the movement of the cement particles, and as a result, the sprayed mortar can be prevented from dripping. This makes it possible to carry out the work without the lath wire mesh used in the normal construction method, thereby reducing costs.

[0022] The casting process of step S40 is a process of casting auxiliary reinforcing bars 60 on the sprayed slope 50. FIG. 4 is an explanatory diagram for explaining the casting process of step S40. The auxiliary reinforcing bars 60 are inserted into holes (e.g., φ40 mm×900 mm, etc.) drilled at a predetermined interval w so as to be at substantially equal intervals in a plan view on the sprayed slope 50 constructed in the spraying process of step S30, so that their heads protrude from the surface of the sprayed slope 50, and the auxiliary reinforcing bars 60 are fixed by injecting grout into the hole gaps. The interval w between adjacent auxiliary reinforcing bars 60 can be appropriately changed according to the construction area of ​​the slope 10 to be repaired, but is preferably set to a range of about 3.0 m to 1.0 m, preferably about 2.5 to 1.5 m, in consideration of the ease of holding the wire netting body by the wire rope described later and the safety of construction. The auxiliary reinforcing bar 60 may be, for example, a deformed reinforcing bar (D19: outer diameter 19.1 mm, length 1000 mm) with a screw groove (M16: outer diameter 16 mm, length 40 mm) formed in the head so as to be able to screw into a hexagonal nut 92 described later and with a zinc-plated surface for rust prevention. If necessary, multiple drainage pipes may be provided at predetermined intervals to drain rainwater etc. that seeps into the ground.

[0023] The covering process in step S50 is a process of covering the surface of the sprayed slope 50 with the wire mesh body 70 via the cast auxiliary reinforcing bars 60, and then holding the wire mesh body with a wire rope. FIG. 5 is a diagram explaining the state in which the surface of the sprayed slope 50 is covered with the wire mesh body 70 via the cast auxiliary reinforcing bars 60, and FIG. 6 is a diagram explaining the state in which the wire mesh body 70 is held with a wire rope 80. As the wire mesh body 70 according to this embodiment, it is preferable to use a flat wire mesh rather than a normally used round wire mesh. The round wire mesh contacts the sprayed slope 50 at points, whereas the flat wire mesh contacts the sprayed slope 50 over an area. This increases the contact area between the sprayed slope 50 and the wire mesh body, and is expected to have the effect of suppressing the sprayed slope 50 and the natural ground. Here, the flat wire is, for example, a wire that is coated with a zinc-iron alloy layer (zinc-10% aluminum-iron alloy layer) on the periphery of an iron wire, and then galvanized (zinc-10% aluminum alloy-plated) round wire is processed into a flat wire by a flat rolling machine. The flat wire is formed into a wire mesh shape to obtain a flat wire mesh (1.6×4.5 mm, 50 mm mesh), which has 1.6 to 3.0 times stronger tensile strength and 1m unit weight (g / m) 13% lighter than a round wire mesh (φ3.2 mm, 50 mm mesh) formed from a round wire. In a vertical drop test using a 200 kg iron ball, the round wire mesh breaks, while the flat wire mesh does not break and shows 1.2 times the strength of the round wire mesh. In the covering process of step S50, the flat wire mesh having such properties is used as the wire mesh body 70 to cover the surface of the sprayed slope 50. At this time, the wire mesh body 70 is laid so that the heads of the auxiliary reinforcing bars 60 project from the surface of the sprayed slope 50 through the mesh of the wire mesh body 70 .

[0024] Next, a method for holding the wire mesh body 70 with the wire rope 80 will be described with reference to Figures 7, 8 and 9. Figure 7 is a diagram for explaining the procedure for attaching a tension member 90 for suspending the wire rope 80 over the auxiliary reinforcing bar 60 cast in step S40. Figure 8 is a diagram for explaining a method for holding the entire wire mesh body 70 laid on the surface of the sprayed slope 50 with the wire rope 80. Figure 9 is a diagram for explaining the state in which the wire rope 80 is suspended over the tension member 90 attached to the auxiliary reinforcing bar 60.

[0025] As shown in FIG. 7(a), the tension member 90 according to this embodiment is a so-called plate with a pipe, and includes a ring portion 90a having an opening 90b formed in the approximate center through which the head of the auxiliary reinforcing bar 60 can be inserted, a hollow pipe portion 90c through which the wire rope 80 is hung, and a base portion 90d connected to the pipe portion 90b and having an opening (not shown) with a larger diameter than the opening 90b. The tension member 90 is attached by exposing the head of the auxiliary reinforcing bar 60 through an opening (not shown) of the base portion 90d, the pipe portion 90c, and the opening 90b of the ring portion 90a (FIG. 7(a)), and then screwing and fastening the head (thread groove) of the auxiliary reinforcing bar 60 with a washer 91 and a hexagonal nut 92, as shown in FIG. 7(b). FIG. 7(c) is a cross-sectional view for explaining the state in which the tension member 90 is attached to the auxiliary reinforcing bar 60. As shown in Fig. 7(c), the base portion 90 of the tensioning member 90 is fixed so as to press down the wire mesh body 70 laid on the surface of the existing sprayed slope 20 and the sprayed slope 50 formed by directly spraying onto the existing sprayed slope 20, so that the wire mesh body 70 can be reliably supported. After the tensioning member 90 is attached to all the cast auxiliary reinforcing bars 60, the wire rope 80 is stretched over the surface of the wire mesh body 70. The wire rope 80 is hung over the pipe portion 90b between the annular portion 90a and the base portion 90d of the tensioning member 90.

[0026] The wire rope 80 is used to hold the entire wire mesh 70 laid on the surface of the sprayed slope 50 in place, according to the procedure shown in Fig. 8. For ease of explanation, the tension member 90 attached to the auxiliary reinforcing bar 60 located at the casting position on the upper left side of the figure is referred to as tension member 90a. 1 The tension member 90a 1 The tension members 90 arranged in the same row are, in order from the top, tension member 90a 2 , 90a 3 , 90a 4 , 90a 5 , 90a 6 Then, the tension member 90a 1 The tension member 90 attached to the auxiliary reinforcing bar 60 located at the casting position to the right of the tension member 90b is 1 and tension member 90b 1The tension members 90 arranged in the same row are, in order from the top, tension member 90b 2 , 90b 3 , 90b 4 , 90b 5 , 90b 6 Furthermore, the tension member 90b 1 The tension member 90 attached to the auxiliary reinforcing bar 60 located at the casting position to the right of the tension member 90c is 1 and tension member 90c 1 The tension members 90 arranged in the same row are, in order from the top, tension member 90c 2 , 90c 3 , 90c 4 , 90c 5 , 90c 6 In this embodiment, the wire rope 80 is stretched between two rows of tension members 90 in a zigzag pattern. Specifically, first, a flexible wire rope 80a having a diameter of 8.0 mm is stretched between the tension members 90a. 1 After being locked and fixed to the tension member 90b located in the lower right direction indicated by the solid arrow (1) in the figure, 2 After being stretched over the tension member 90a located in the lower left direction indicated by the solid arrow (2) in the figure, 3 Next, the tension member 90b located in the lower right direction indicated by the solid arrow (3) in the figure is 4 After being stretched over the tension member 90a located in the lower left direction indicated by the solid arrow (4) in the figure, 5 and finally, the tension member 90b located in the lower right direction indicated by the solid arrow (5) in the figure. 6 Similarly, the wire rope 80b is fixed to the tension member 90b. 1 After being engaged and fixed to the tension member 90a located in the lower left direction indicated by the dotted arrow (1)' in the figure, 2 After being stretched over the wire, the tension member 90b located in the lower right direction indicated by the dotted arrow (2)' in the figure is 3 Next, the tension member 90a located in the lower left direction indicated by the dotted arrow (3)' in the figure is 4 After being stretched over the wire, the tension member 90b located in the lower right direction indicated by the dotted arrow (4)' in the figure is 5 and finally, the tension member 90a located in the lower left direction indicated by the dotted arrow (5)' in the figure. 6The wire rope 80 can be secured to the tension member 90 by using a wire clip 100. A similar operation is performed on the tension member 90b. 1-6 and tension member 90c 1-6 Between the tension member 90c 1-6 and tension member 90d 1-6 Between the tension members 90d 1-6 and tension member 90e 1-6 Between the tension members 90e 1-6 and tension member 90f 1-6 This is done sequentially between the wire rope 80 and the wire mesh body 70, and finally the wire rope 80 and the wire mesh body 70 are connected by a plurality of connecting coils 110, thereby completing the holding of the entire wire mesh body 70 by the wire rope 80.

[0027] As shown in FIG. 8, when the wire rope 80 is stretched between the tension members 90, there are some places where one tension member 90 is shared by two wire ropes 80, for example, wire ropes 80a and 80d in tension members 90b2 and 90b4, or wire ropes 80b and 80c in tension members 90b3 and 90b5. In this case, as shown in the plan view of FIG. 9(a) and the perspective view of FIG. 9(b), it is preferable to stretch the two wire ropes 80 along the pipe portion 90b of the tension member 90 so that they cross in an X-shape, rather than winding each of the two wire ropes 80 around the pipe portion 90b of the tension member 90. This prevents the tension member 90 (auxiliary reinforcing bar 60) from following unexpected movements of the wire rope 80 or the wire mesh body 70, and suppresses the occurrence of stress in a localized position in response to an external force that occurs, thereby improving the robustness of the restraint body made of the flat wire mesh and wire rope. sex It is possible to maintain the above.

[0028] Here, in order to confirm the load-bearing capacity of the support structure consisting of flat wire mesh and wire rope, a test specimen consisting of 2.0m x 2.0m flat wire mesh held down by wire rope was loaded with one sandbag weighing 1.0t each and strength was confirmed. As a result, it was confirmed that the test specimen could withstand loads of up to 8.0t without breaking. The reason for setting the load-bearing limit at 8.0t is that assuming the weathered portion at the back is 1.0m, the load capacity limit would be approximately 8.0t (2.0m x 2.0m x 1.0m x 20kN / m 3 This strength test confirmed that the restraining structure, consisting of the flat wire mesh and wire rope, has sufficient load-bearing capacity against collapsed soil and sand caused by weathering of the ground.

[0029] In this way, in the repair method according to this embodiment, adhesive mortar is sprayed while leaving the existing sprayed surface intact, the surface of the sprayed slope is covered with a wire mesh body, and then the wire mesh body is secured with a wire rope, thereby making it possible to suppress both the existing sprayed surface and the weathered soil and sand behind it.

[0030] In addition, the repair method according to this embodiment is expected to significantly shorten the construction period compared to conventional repair methods. For example, in the conventional repair method, 2 In this case, it will take about 8 days to set up the temporary protective fence, about 13 days to demolish the existing sprayed slope, about 3 days to transport and process the sprayed hull, about 17 days to shape the slope (remove the weathered layer), about 10 days to spray mortar and concrete including wire mesh installation, and about 5 days to remove the temporary protective fence, totaling about 56 days. In contrast, with the repair method according to this embodiment, if the construction area is 1,000 m, it will take about 10 days to remove the temporary protective fence. 2In this case, the entire construction can be completed in a total of about 39 days, including one day for the installation process of a simple temporary protective fence, about five days for the cleaning process of the existing sprayed slope, about six days for the spraying process of constructing the sprayed slope by spraying adhesive mortar on the existing sprayed slope after cleaning, about 19 days for the casting process of casting reinforcing steel bars at the specified locations of the sprayed slope, and about eight days for the covering process of covering the surface of the sprayed slope with a wire mesh body through the reinforcing steel bars and then holding the wire mesh body with wire ropes. In addition, the repair method according to this embodiment does not require the installation of a large-scale temporary protective wall, and it is possible to reduce the generation of a large amount of industrial waste, which can lead to significant cost reductions.

[0031] For these reasons, the present invention can provide a repair method for existing sprayed slopes that makes it possible to reduce the generation of large amounts of industrial waste and shorten the construction period without requiring the installation of large-scale temporary protective walls, and that reduces the possibility of re-construction even if damage such as peeling, collapse, or cracks of the sprayed surface occurs due to deterioration or aging due to weathering or a natural disaster. [Explanation of symbols]

[0032] 10 Slope to be repaired, 20 Existing sprayed slope, 30 Sprayed hose, 40 Adhesive mortar, 50 Sprayed slope, 60 Auxiliary reinforcing bar, 70 Wire mesh, 80 Wire rope, 90 Tension member, 90a Ring portion, 90b Pipe portion, 90c Pipe portion, 90d Base portion, 91 Washer, 92 Hexagonal nut

Claims

1. A cleaning process for cleaning the damaged existing sprayed slope; A spraying process of spraying an adhesive mortar containing an admixture containing carbon fiber onto the existing sprayed slope after cleaning to construct the sprayed slope; a casting process for casting reinforcing bars into the holes drilled at predetermined intervals on the sprayed slope so that the squares are approximately equally spaced when viewed from the front, the holes reaching the natural ground, the heads of which protrude from the surface of the sprayed slope; and a covering process for covering the surface of the sprayed slope with a flat wire mesh body that contacts the surface of the sprayed slope with the cast reinforcing steel bar, and then holding the flat wire mesh body with a wire rope. The adhesive mortar had a tensile adhesive strength of 0.88 N / mm according to JIS A 1171. ２ or more tensile adhesive strength This is a repair method for existing sprayed slopes.

2. The reinforcing steel bar exposed from the surface of the sprayed slope is provided with a tension member, The wire mesh laid on the surface of the sprayed slope is held by the wire rope that is hung between the tension members of the reinforcing steel bars in a zigzag shape. A repair method for an existing sprayed slope according to claim 1, characterized in that

3. The reinforcing bars should be installed at intervals of 3.0 to 1.0 m. The repair method for an existing slope according to claim 1,

Images