Sprayed frame construction method

Abstract

To provide a spray slope frame construction method which contributes to long life of a slope frame.SOLUTION: A spray slope frame construction method which does not use a frame mold constructs a slope frame 5 by spraying cement containing material 4 to a long reinforcing-bar substitute material 2 and an assembly frame 3 which holds the reinforcing-bar substitute material 2. The reinforcing-bar substitute material 2 is constituted by integrating a plurality of fiber bundles of fiber-reinforced plastic. The reinforcing-bar substitute material 2 contains the fiber bundles which are crossed in a braid-like manner. Regarding the plurality of integrated fiber bundles, the restraint of the fiber bundles with each other is partially relaxed, and the reinforcing-bar substitute material 2 is deformed so as to correspond to the irregularity of a slope N.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to, for example, a sprayed frame construction method that does not require formwork. [Background technology]

[0002] One method for reinforcing the slopes of roads, developed land, etc. is the sprayed frame method, in which a mesh such as wire mesh is laid on the slope, reinforcing bars arranged in a grid pattern in plan view are held at an appropriate height on this mesh by an assembly frame, and a cement-containing material (mortar or concrete) is sprayed onto these reinforcing bars and the assembly frame to construct a slope frame with a segmented cross section (Patent Document 1).This method has the advantage that the slope frame can be easily formed on the slope. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-213693 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case of a crest frame constructed using the above-mentioned method, even if the mortar or concrete deteriorates, it is possible to repair it to a certain extent, but if the reinforcing bars deteriorate due to rust or other reasons, it is difficult to repair them, and this is a factor that prevents the crest frame from having a long lifespan.

[0005] The present invention has been made in consideration of the above matters, and an object of the present invention is to provide a sprayed crib construction method that contributes to extending the life of the crib. [Means for solving the problem]

[0006] In order to achieve the above object, the sprayed frame construction method according to the present invention is a sprayed frame construction method that does not use formwork, and is a method of forming a long reinforcing bar substitute material and a reinforcing bar substitute material. In two tiers, top and bottom The cement-containing material is sprayed onto the retained assembly frame. The upper edge of the longitudinal cross section in the direction perpendicular to the extension direction of the reinforcing bar substitute is a semi-cylindrical arch that is convex upward. Building a legal framework The steel bar substitute is made of carbon fiber reinforced plastic, has a nominal diameter of 9.0 mm or more, and a nominal cross-sectional area of ​​63.0 mm. 2 The design standard strength is 18N / mm. 2 In both the positive bending test and the negative bending test, specimens were constructed by placing reinforcement in mortar so that the axis was located 50 mm and 100 mm below the apex of the mortar. When the above-mentioned steel bar substitute was used as the reinforcement, bending failure preceded shear failure. When comparing the case where the above-mentioned steel bar substitute was used as the reinforcement with the case where deformed steel bars (SD295, D10) were used, the maximum load until bending failure was greater in the former, and the crack width of the mortar at the time of bending failure was smaller in the former. (Claim 1).

[0007] In the above-mentioned sprayed frame construction method, the reinforcing bar substitute may be formed by integrating a plurality of fiber bundles of fiber reinforced plastic (claim 2).

[0008] In the above-mentioned sprayed framework construction method, the reinforcing bar substitute may include the fiber bundles crossed in a braided cord shape (claim 3).

[0009] In the above-mentioned sprayed frame construction method, the mutual constraint between the integrated fiber bundles may be partially relaxed, and the reinforcing bar substitute material may be deformed to conform to the unevenness of the slope (claim 4).

[0010] In the above-mentioned sprayed frame construction method, the relaxation of the restraint may be carried out by applying an external force or heat to the reinforcing bar substitute (claim 5).

[0011] In the above-mentioned sprayed frame construction method, The width of the vertical cross section in the direction perpendicular to the extension direction of the reinforcing bar substitute of the semi-cylindrical frame is 350 mm and the height is 150 mm, and the upper and lower reinforcing bar substitutes are arranged so that their axes are located 50 mm and 100 mm below the apex of the frame, respectively. This is also possible (claim 6).

[0012] In the above-mentioned sprayed frame construction method, granular materials may be fixed to the surface of the reinforcing bar substitute (claim 7).

[0013] In the above-mentioned spraying frame construction method, , law A vegetation substrate may be placed within the frame of the frame (claim 8). [Effects of the Invention]

[0014] The present invention provides a sprayed crest construction method that contributes to extending the life of crests.

[0015] That is, in the sprayed concrete frame construction method of the invention according to each claim of the present application, by using a material that is resistant to deterioration as a substitute for reinforcing bars, it is possible to extend the life of the concrete frame.

[0016] Fiber reinforced plastic is a material that is free from oxidation and does not rust or corrode, and in the sprayed frame construction method of the invention according to claim 2, which uses this fiber reinforced plastic as a rebar substitute, the rebar substitute has excellent durability, ensuring the above-mentioned long life. In addition, because fiber reinforced plastic is a lightweight and strong material, this construction method gives the rebar substitute strength equivalent to that of rebar, while also making it possible to transport and install it with little effort.

[0017] The spray-coated frame construction method of the invention according to claim 3 has the advantage that by creating unevenness on the surface of the rebar substitute material using braided fiber bundles, the adhesion (pull-out resistance) between the rebar substitute material and the cement-containing material can be improved, and the tensile strength of the fibers that make up the fiber bundles crossed in a braided cord shape can be fully utilized.

[0018] In the sprayed crib construction method of the invention according to claim 4, the reinforcing bar substitute material is deformed to correspond to the unevenness of the slope surface, making it easy to optimize the shape of the crib to be constructed.

[0019] In the sprayed frame construction method of the invention according to claim 5, external force or heat can be applied to appropriate parts of the reinforcing bar substitute material to deform it while observing the unevenness of the slope, making it easy to make the shape of the reinforcing bar substitute material correspond to the unevenness of the slope.

[0020] Carbon fiber reinforced plastic has excellent machinability, and the claim that the steel bar substitute material is made of carbon fiber reinforced plastic is Item 1 In the sprayed frame construction method of the present invention, it becomes easy to cut the reinforcing bar substitute to the optimum length on-site, thereby improving workability.

[0021] In the sprayed frame construction method of the invention according to claim 7, the granular material adhered to the surface of the reinforcing bar substitute can improve the adhesion (pull-out resistance) between the reinforcing bar substitute and the cement-containing material.

[0022] In the spray-casting frame construction method of the invention according to claim 8, the cross section of the frame to be constructed is Kamaboko mold and Do itThis results in a sloped crest that has excellent drainage properties for surface water and is less likely to retain water within the crest, and because the shape of this sloped crest makes it easy for grown plants to cover it, it creates an excellent landscape, especially after planting has been established. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is an explanatory diagram of a spraying frame construction method according to an embodiment of the present invention. FIG. [Figure 2] (A) is an explanatory diagram of the evaluation test of the steel bar substitute material, (B) is an explanatory diagram of the test specimen used in the evaluation test, and (C) is an explanatory diagram showing the installation position of the measuring equipment used in the evaluation test. DETAILED DESCRIPTION OF THE INVENTION

[0024] An embodiment of the present invention will be described below.

[0025] The sprayed crest construction method shown in Figure 1 involves spraying a cement-containing material 4 onto reinforcing bar substitute materials 2 and an assembly frame 3 on a mesh body 1 laid on a previously prepared slope N while ensuring an appropriate cover thickness, to construct a crest 5 (a bulging body that contains reinforcing bar substitute materials 2 and has an upwardly convex arched upper edge in a vertical cross section perpendicular to the direction in which the reinforcing bar substitute materials 2 extend) that has a partial circular (approximately semicircular) cross section and a lattice-like shape when viewed from above. After that, a vegetation substrate 6 is placed within each frame of the crest 5 to promote greening.

[0026] In this spray frame construction method, by making the cross section of the constructed slope frame 5 a partial circle, a slope frame 5 is obtained that has excellent drainage properties for surface water (water flowing on the slope N) and is less likely to accumulate within the frame.Furthermore, due to its shape, this slope frame 5 is easily covered with grown vegetation, so it creates an excellent landscape, especially after vegetation has been established.

[0027] Here, as the mesh body 1, for example, a wire mesh such as JIS G 3552 diamond-shaped wire mesh (wire diameter 2 mm, mesh size 50 mm) can be used.

[0028] The configuration, number, arrangement, etc. of the rebar substitutes 2 and assembly frame 3 may be determined appropriately depending on the crest 5 to be constructed. In the example of Fig. 1, the assembly frame 3 holds two rebar substitutes 2 in two tiers, one above the other, while keeping them above the ground. When holding them in this state, the rebar substitutes 2 may be fixed to the assembly frame 3 using an appropriate binding material, etc. For example, the assembly frame 3 may be manufactured by Nippon Shokusei Co., Ltd. under the product names Gatender, Dizer, or Tetraizer (all with a wire diameter of 5 mm), etc.

[0029] The cement-containing material 4 may be mortar, concrete, etc. that corresponds to the crest 5 to be constructed, and the fine aggregate, cement, etc. to be mixed may be standard products that comply with JIS standards.

[0030] The vegetation substrate 6 can be made of a material selected appropriately according to the type of vegetation (greening) to be carried out within the framework of the slope 5. For example, a mixture of soil, organic material, water-retaining material (soil improvement material), etc., and seeds of turfgrass, wild grass, shrubs, etc. can be used.

[0031] In addition, main anchors and auxiliary anchors for fixing the reticle 1 are driven into appropriate locations in the reticle 1, and intersection anchors for tying the reticle 2 with appropriate tie wires are driven into locations where the reinforcing bar substitutes 2 intersect in a plan view (neither is shown). These anchors are, for example, cut and processed steel bars conforming to JIS G 3112, and the main anchors can be 16 mm in diameter and 400 mm in length, the auxiliary anchors can be 9 mm in diameter and 200 mm in length, and the intersection anchors can be 16 mm in diameter and 400 mm or 750 mm in length.

[0032] While the conventional sprayed frame construction method uses reinforcing bars, this method uses reinforcing bar substitute material 2 instead of reinforcing bars, which is one of the features of this method. The reinforcing bar substitute material 2 will be described below.

[0033] First, from the perspective of extending the lifespan of the constructed slope frame 5, it is preferable to use a material that is resistant to deterioration for the rebar substitute 2. One such material is fiber-reinforced plastic, which, unlike rebar, is immune to oxidation and does not rust or corrode. Using fiber-reinforced plastic for the rebar substitute 2 gives the rebar substitute 2 excellent durability, ensuring the aforementioned long lifespan. Furthermore, because fiber-reinforced plastic is a lightweight and strong material, it can provide the rebar substitute 2 with strength equivalent to that of rebar, while also enabling its transportation and installation to be carried out with minimal effort. The improved workability achieved by reducing the weight of the rebar substitute 2 is a significant benefit, especially on steep slopes N.

[0034] The steel bar substitute 2 may be formed by integrating a plurality of fiber bundles of fiber reinforced plastic. The fiber bundle may be a bundle of a plurality of fibers (fibers, filaments) of fiber reinforced plastic that are untwisted, or may be a bundle of fibers that are twisted together. The method of integrating a plurality of fiber bundles may be any appropriate method, such as crossing or twisting them in a braided cord (e.g., an eight-stranded cord), and the plurality of fiber bundles may be combined and integrated to form a two-layer structure consisting of an inner layer and an outer layer. The number of fibers that make up the fiber bundle and the number of fiber bundles are not particularly limited.

[0035] In particular, by creating unevenness on the surface of the reinforcing bar substitute material 2 by using multiple fiber bundles crossed in a braided cord shape, there are advantages such as improving the adhesion (pull-out resistance) between the reinforcing bar substitute material 2 and the cement-containing material, and fully utilizing the tensile strength of the fibers that make up the fiber bundles crossed in a braided cord shape.

[0036] Furthermore, by partially relaxing the mutual constraints between the integrated fiber bundles and deforming the reinforcing bar substitute material 2 to accommodate the unevenness of the slope N, it becomes easier to optimize the shape of the slope frame 5 to be constructed.

[0037] The mutual constraints between the fiber bundles can be relaxed by applying an external force (such as a bending force) or heat (such as heating with a burner) to the reinforcing bar substitute 2. In this case, applying an external force or heat to appropriate portions of the reinforcing bar substitute 2 while observing the unevenness of the slope N makes it easy to change the shape of the reinforcing bar substitute 2 to match the unevenness of the slope N. More specifically, partially reducing the elastic restoring force of the reinforcing bar substitute 2 by partially peeling some of the fiber bundles from each other or plastically deforming only some of the fiber bundles makes it easy to maintain the shape of the reinforcing bar substitute 2 to match the unevenness of the slope N. In this case, measures can be taken, such as increasing the fiber thickness or diameter of the fiber bundles or increasing the number of fiber bundles used, for the reinforcing bar substitute 2 before reducing its elastic restoring force, so that the reinforcing bar substitute 2 after its elastic restoring force has been reduced will have sufficient properties, such as sufficient tensile strength and elastic modulus, required to maintain the slope 5 after construction.

[0038] The matrix resin, fibers, and manufacturing method of the fiber-reinforced plastic used in the rebar substitute 2 are not particularly limited as long as they impart the necessary performance to the resulting rebar substitute 2, and the matrix resin may be treated with a sizing agent, a coupling agent, or the like. Here, the matrix resin may be either a thermosetting resin (e.g., epoxy resin) or a thermoplastic resin (e.g., methyl methacrylate), but it is preferable to use a thermoplastic resin when, as described above, it is intended to alleviate the mutual constraints between the fiber bundles by applying heat.

[0039] If the reinforcing bar substitute 2 is made of carbon fiber reinforced plastic, the reinforcing bar substitute 2 can be easily cut to an optimum length on-site because carbon fiber reinforced plastic has excellent machinability, thereby improving workability. The carbon fiber (filament) used may have, for example, a filament count of 12,000, a fineness of 800 tex, a tensile strength of 5,100 MPa, a tensile modulus of elasticity of 245 GPa, an elongation of 2.1%, and a density of 1.78 g / cm. 3 In this case, the rebar substitute 2 should have a Young's modulus close to that of rebar (for example, 150,000 N / mm 2Young's modulus or more) and tensile strength 2.6 times or more than that of rebar (SD295A) (for example, approximately 2000N / mm 2 The inventors have confirmed that it is possible to reduce the weight to about 1 / 5 of that of reinforcing bars while maintaining the above properties.

[0040] Then, by fixing granular material such as sand to the surface of the reinforcing bar substitute 2 by adhesive or the like, it is possible to improve the adhesion (pull-out resistance) between the reinforcing bar substitute and the cement-containing material. The granular material may be selected to have an appropriate particle size or the like in consideration of the above-mentioned adhesion or the like, and the fixing method is not particularly limited, but it is preferable to fix the granular material approximately uniformly over the entire surface of the reinforcing bar substitute 2.

[0041] The tests conducted to evaluate the reinforcing bar substitute 2 will be described below.

[0042] (Test specimen) Three types of specimens (1) to (3) were prepared as test specimens. Each specimen was constructed by hardening mortar to form a semi-cylindrical shape with a length of 3000 mm, a width of 350 mm, and a thickness (height) of 150 mm, as shown in Figures 2(A) and (B). Reinforcement materials were embedded in the mortar at positions 50 mm and 100 mm from the upper edge.

[0043] [Table 1] The mortar mix used for each specimen is shown in Table 1, and the design strength is 18 N / mm 2 It was decided.

[0044] Steel bars (SD295, D10) and two types of sand-attached CFRP braided rods (both classified as steel bar alternative 2) were prepared as reinforcing materials. Steel bars were used as reinforcing materials for specimen (1), CFRP braided rods (Fibex Corporation, product number RC7S) for specimen (2), and CFRP braided rods (Fibex Corporation, product number RC9S) for specimen (3). Anchorage rods (RC7S) were installed at the ends of specimens (2) and (3) to prevent them from coming loose during the loading test. The specifications of the steel bars and the two types of CFRP braided rods are shown in Tables 2 and 3.

[0045] [Table 2]

[0046] [Table 3]

[0047] (Loading method) As shown in Figure 2(A), the structure was simply supported with a span of 2500 mm, with a 500 mm equal bending section. Two load cases were used: monotonic loading and cyclic loading. The cyclic load value was applied in steps of 1.0 kN up to 3.0 kN, and once it exceeded 3.0 kN, it was monotonic loading until failure. In the test, it was assumed that collapse would occur when the mortar strain was around 3500 μ.

[0048] As shown in Figure 2(A), each specimen was subjected to a positive bending test (with the curved surface facing upwards) which primarily assumed a collapse at the top of the slope, and a negative bending test (with the curved surface facing downwards) which primarily assumed a collapse in the middle of the slope.

[0049] (Measurement items) The measurement items are the following five. 1) Load: Based on the universal testing machine and load cell values 2) Reinforcement strain: As shown in Figure 2(C), strain gauges were installed at five locations on the top and bottom of the reinforcement material inserted into the test specimen. 3) Concrete strain: As shown in Figure 2(C), a strain gauge was installed at the center of the concrete surface and measured. 4) Displacement (span center): Measured by installing displacement meters at both supports and the center. 5) Crack width: Measured by placing a π gauge at the cracked area immediately after the crack occurred.

[0050] (Material test results) The test results for mortar strength and elastic modulus during the loading test were: 19 days old, elastic modulus Ec = 21,400 N / mm 2 , compressive strength f'ck=38.6N / mm 2 , tensile strength ft=3.6N / mm 2 The ultimate strain was εcu=3000μ.

[0051] (Strength and modulus of elasticity of reinforcement) The test results for the strength and elastic modulus of the reinforcement used in the loading test are shown in Table 4.

[0052] [Table 4]

[0053] (Load test results) The results of the load test are shown in Table 5.

[0054] [Table 5]

[0055] From the above test results, it can be seen that the reinforcing bar substitute material 2 exhibits functions equal to or superior to those of reinforcing bars and can be used in place of reinforcing bars.

[0056] It should be noted that the present invention is not limited to the above-described embodiment, and can be practiced in various modified forms without departing from the spirit of the present invention. For example, the following modifications can be mentioned.

[0057] The slope frame 5 is not limited to a grid-like shape in plan view, and may have other shapes. Furthermore, if greening is not required within each frame of the slope frame 5, protective work (for example, spraying a hardening material or filling with crushed stone or other filler material) may be carried out instead of greening work.

[0058] It goes without saying that the modifications given in this specification may be combined as appropriate. [Explanation of symbols]

[0059] 1 Reticulum 2. Steel bar substitutes 3 Assembly Frame 4. Cement inclusions 5 Legal Framework 6. Vegetation substrate N slope

Claims

1. This is a spray-casting frame construction method that does not use formwork, in which a cement-containing material is sprayed onto long reinforcing bar substitutes and an assembly frame that holds the reinforcing bar substitutes in two layers, one above the other, to construct a semi-cylindrical frame whose upper edge in a vertical cross section in a direction perpendicular to the direction in which the reinforcing bar substitutes extend forms an upwardly convex arch; The steel bar substitute is made of carbon fiber reinforced plastic, has a nominal diameter of 9.0 mm or more, and a nominal cross-sectional area of ​​63.0 mm 2 or more; This sprayed frame construction method is characterized in that in both positive bending tests and negative bending tests, test specimens were constructed by placing reinforcing material in mortar with a design standard strength of 18 N / mm2 that hardened to form a semi-cylindrical shape 3000 mm long, 350 mm wide, and 150 mm high, with the axis of the reinforcing material positioned 50 mm and 100 mm below the apex.When the above-mentioned steel bar substitute was used as the reinforcing material, bending failure preceded shear failure, and when the above-mentioned steel bar substitute was used as the reinforcing material and deformed steel bars (SD295, D10) were used as the reinforcing material, the maximum load until bending failure was greater in the former and the crack width of the mortar at bending failure was smaller in the former.

2. 2. The sprayed frame construction method according to claim 1, wherein the steel bar substitute is formed by integrating a plurality of fiber bundles of fiber reinforced plastic.

3. The sprayed frame construction method according to claim 2 , wherein the reinforcing bar substitute includes the fiber bundles crossed in a braided cord shape.

4. 4. The sprayed frame construction method according to claim 2 or 3, wherein the mutual constraint between the integrated fiber bundles is partially relaxed, and the reinforcing bar substitute material is deformed to correspond to the unevenness of the slope.

5. The sprayed frame construction method according to claim 4, wherein the relaxation of the restraint is carried out by applying an external force or heat to the reinforcing bar substitute.

6. A spray-coated frame construction method as described in Claim 5, wherein the width of the longitudinal cross section in a direction perpendicular to the extension direction of the reinforcing bar substitute material of the kamaboko-shaped frame is 350 mm and the height is 150 mm, and the upper and lower two tiers of reinforcing bar substitute material are respectively positioned so that their axis is located 50 mm and 100 mm below the apex of the frame.

7. 7. The sprayed frame construction method according to claim 6, wherein granular material is fixed to the surface of the reinforcing bar substitute.

8. A spray-on frame construction method as described in claim 7, in which a vegetation substrate is arranged within the frame of a crest.

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