Composite structure and construction method for suppressing rolling of stones

Abstract

To provide a composite structure body that can simply suppress rolling of stones and a method that can suppress rolling of stones existing on ground surface.SOLUTION: A composite structure body 10 includes stones 11 lying on ground surface G and a polyurethane foam body 20 attached on the stones 11 so as to follow their surface shapes. The polyurethane foam body 20 has a high performance of entering gaps and filling the voids, compared to filling materials such as mortar and concrete. Therefore, the polyurethane foam body 20 adhering to the stones 11 can suppress the stones from rolling around.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a composite structure and a construction method for suppressing the rolling of stones existing on the ground.

Background Art

[0002] Patent Document 1 discloses a rockfall prevention method for preventing the falling and sliding of pumice on a slope. This method is a method of constructing a retaining wall to support the pumice until it covers all or part of the pumice on the lower side of the target pumice.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the method such as that of Patent Document 1, a large amount of concrete is used to construct the retaining wall, and large-scale equipment such as forms and heavy machinery for placing the concrete is used. For this reason, a technique for more simply preventing rockfalls is required.

[0005] The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a composite structure that can simply suppress the rolling of stones. Another object is to provide a construction method for suppressing the rolling of stones existing on the ground that can simply suppress the rolling of stones.

Means for Solving the Problems

[0006] The composite structure of the present disclosure includes: a stone existing on the ground; and a polyurethane foam attached along the surface shape of the stone.

[0007] Compared with packing materials such as mortar and concrete, for example, the polyurethane foam has a high performance of entering gaps and filling voids. Therefore, the rolling of the stone can be suppressed by the polyurethane foam adhering to the stone.

[0008] The method for suppressing the rolling of stones existing on the ground of the present disclosure is a method for suppressing the rolling of the stone by adhering a polyurethane foam along the surface shape of the stone.

[0009] According to this method, by simply injecting the polyurethane foam raw material, a polyurethane foam adhering along the surface shape of the stone can be formed. Therefore, the polyurethane foam can be formed without performing complicated steps, and the rolling of the stone can be suppressed.

Advantages of the Invention

[0010] According to the present disclosure, a composite structure capable of easily suppressing the rolling of stones can be provided. Further, according to the present disclosure, a method for suppressing the rolling of stones existing on the ground, which can easily suppress the rolling of stones, can be provided.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0012] Here, desirable examples of the present disclosure are shown. The polyurethane foam may be attached to the lower surface side of the stone. According to this configuration, initial rolling of the stone can be suppressed, and rolling of the stone can be effectively suppressed.

[0013] A plurality of the stones are gathered with gaps partially opened. The polyurethane foam may be filled in the gaps and attached to each of the plurality of stones. Rolling, unlike sliding, allows each part of a plurality of stones to move in different directions. According to the above configuration, the polyurethane foam adheres to each of the plurality of stones, and by suppressing the rolling of the plurality of stones mutually, the rolling of the plurality of stones can be suppressed.

[0014] First, the composite structure 10 of an embodiment of the present disclosure will be described with reference to FIG. 1. Note that the present disclosure is not limited to these examples, and is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0015] As shown in FIG. 1, the composite structure 10 suppresses the rolling of stones 11 such as pumice and cobblestones existing on the ground G by the polyurethane foam 20. The ground G is not limited to a slope, but the technique of the present disclosure is more effective when it is a slope.

[0016] The composite structure 10 includes stones 11 existing on the ground G and a polyurethane foam 20 attached along the surface shape of the stones 11. The stones 11 have an arbitrary three-dimensional shape and have convex portions at least in part. Also, the surface of the stones 11 has irregularities. Even a stone that appears to have a seemingly smooth surface has, for example, small recesses that allow the polyurethane foam raw material to enter. The surface of the polyurethane foam 20 that adheres to the stones 11 has a shape following such a surface shape of the stones 11. In the present disclosure, "adhesion" mainly means mechanical bonding by fitting the uneven structures of the stones 11 and the polyurethane foam 20 to each other. Therefore, the stones 11 may be dirty with soil, sand, moss, etc. that interfere with chemical and physical bonding with the polyurethane foam 20.

[0017] The stones 11 are gathered in plurality with gaps 13 partially open. The plurality of stones 11 are gathered, for example, by being stacked on one another. The gaps 13 may be formed in a mesh shape between the plurality of stones 11, or may be formed in a crack shape between two cracked stones 11. In this embodiment, an example of a composite structure 10 including a plurality of stones 11 and a method for suppressing the rolling of the plurality of stones 11 will be described, but the composite structure 10 and the method for suppressing the rolling of the stones 11 may be applied to a single stone.

[0018] The polyurethane foam 20 is attached to the lower surface 12 side of the stone 11. The polyurethane foam 20 fills the gap 13 between the lower stone 11 and the ground G. The polyurethane foam 20 also extends around the lower stone 11 and is provided so as to surround the lower stone 11. Although the polyurethane foam 20 has a lower strength compared to structures such as retaining walls, it suppresses the rolling of the stone 11 by wrapping the entire stone 11.

[0019] The polyurethane foam 20 is attached to the lower stone 11 among the plurality of stacked stones 11 and also to the stone 11A located on the lower side of the slope of the ground G. The polyurethane foam 20 has a portion 21 that adheres to the surface on the lower side of the slope of the ground G in the stone 11A. The portion 21 of the polyurethane foam 20 functions as a stopper that suppresses the initial rolling when the stone 11A rolls on the ground G. The rolling of the stone 11A can spread to other stones 11 and become a factor in large-scale rockfalls. By suppressing the rolling of the stone 11A, which has a large impact on other such stones 11, large-scale rockfalls can be effectively prevented.

[0020] The polyurethane foam 20 is filled in the gap 13 and is attached to each of the plurality of stones 11. The polyurethane foam 20 is provided over substantially the entire area where the plurality of lower stones 11 exist. In other words, the polyurethane foam 20 is provided in a mesh shape between adjacent lower stones 11.

[0021] The polyurethane foam 20 may be either a flexible urethane foam or a rigid urethane foam, but is preferably a rigid urethane foam. The rigid urethane foam has a higher closed-cell ratio than the flexible urethane foam and is a foam with higher hardness and lower resilience. When using the rigid urethane foam, a certain degree of hardness and shape retention can be ensured in the polyurethane foam 20 itself, and the rolling of the stone 11 can be preferably suppressed.

[0022] The polyurethane foam 20 is formed at the construction site by reacting two liquid raw materials, namely, a main agent (liquid A) mainly composed of polyol, a crosslinking agent, a foaming agent, etc., and a curing agent (liquid B) mainly composed of isocyanate. That is, the polyurethane foam 20 is a two-component polyurethane foam. The curing time of the two-component urethane foam is shorter than that of the one-component polyurethane foam, and the raw materials are less likely to flow out from the gap 13 between the stones 11 to the periphery of the stones 11 before foaming and curing. The curing time of the two-component urethane foam can be appropriately designed according to the range where the polyurethane foam 20 is provided and the volume of the gap 13.

[0023] From the perspective of reducing the raw materials transported to the construction site, the foaming ratio of the polyurethane foam 20 is preferably 10 times or more, more preferably 20 times or more, and even more preferably 30 times or more. The upper limit value of the foaming ratio of the polyurethane foam 20 is not particularly limited, but is usually 40 times or less.

[0024] Next, a method for suppressing the rolling of the stone 11 existing on the ground G will be described. This method is a method for suppressing the rolling of the stone 11 by attaching the polyurethane foam 20 along the surface shape of the stone 11. This method does not require cleaning the adhesive surface of the stone or drilling holes in the stone and driving in anchors in order to adhere an adhesive to the stone. That is, this method can be carried out by directly attaching the polyurethane foam 20 to the stone 11 existing in the natural state.

[0025] Specifically, as shown in FIG. 2, the nozzle 22 is inserted into the gap 13 between the stones 11, and the polyurethane foam raw material is injected. When a plurality of stones 11 are stacked in large numbers or when each individual stone 11 is large, the polyurethane foam raw material may be injected at multiple locations in the gap 13, or a long nozzle may be used to spread the polyurethane foam raw material to every corner of the gap 13.

[0026] Before curing, the polyurethane foam 20 flows downward due to its own weight and enters, for example, between the lower stone 11 and the ground G. At this time, by lengthening the curing time of the polyurethane foam 20, the flow of the polyurethane foam raw material may be promoted to increase the range into which the polyurethane foam raw material enters. Further, as the polyurethane foam 20 expands in volume due to foaming, it spreads to every corner of the gap 13 and the recesses of the stone 11. Then, the polyurethane foam 20 is formed in a manner that fills part or all of the gap 13. When the injected polyurethane foam raw material foams and cures, a polyurethane foam 20 shaped following the surface of the stone 11 is obtained in the gap 13.

[0027] As described above, the composite structure 10 of the present embodiment includes the stone 11 existing on the ground G and the polyurethane foam 20 adhering along the surface shape of the stone 11. According to the composite structure 10, the rolling of the stone 11 can be easily suppressed. Hereinafter, the operation of the present disclosure will be described by demonstration experiments.

[0028] A test piece with concrete formed into a cylindrical shape was used as test stone 11, and an experiment regarding the rolling of test stone 11 was conducted. The size of test stone 11 for the test was set to a bottom diameter of 100 mm and a height of 200 mm. First, a plate 30 corresponding to the ground G was prepared. A convex portion 32 was provided on the upper surface 31 of plate 30. The convex portion 32 had a height of 6 mm from the upper surface 31 and was long in one direction. With the height direction of test stone 11 aligned with the length direction of convex portion 32, as shown in FIG. 3, two test stones 11 were placed on the upper surface 31 of plate 30. From this state, the inclination angle of the upper surface 31 with respect to the horizontal plane was gradually increased, and the inclination angle of the upper surface 31 (hereinafter referred to as the critical angle) when at least one of the two test stones 11 crossed over the convex portion 32 and rolled to the lower side of the inclination was determined.

[0029] In the example, a polyurethane foam raw material was injected between the two test stones 11 to form a polyurethane foam 20. In the comparative example, the polyurethane foam 20 was not formed. In the example and the comparative example, the respective critical angles were determined. The state of the experiment according to the example is shown in the photograph of FIG. 4. As a result of the experiment, the critical angle of the example was 53.5 degrees. The critical angle of the comparative example was 32 degrees. That is, the critical angle of the example was larger than that of the comparative example. It is presumed that this is because the rolling of test stone 11 was suppressed by the polyurethane foam 20, increasing the inclination angle required to cross over the convex portion 32.

[0030] Next, the bonding state between the polyurethane foam 20 and the test stone 11 in the example was examined. FIG. 5 is a photograph of the adhesion surface of the polyurethane foam 20 to the test stone 11. The adhesion surface in the left photograph is the adhesion surface to the test stone 11 on the right side, and the adhesion surface in the right photograph is the adhesion surface to the test stone 11 on the left side. The adhesion surface of the polyurethane foam 20 was shaped in a cross-sectional arc shape along the side surface of the test stone 11 and was shaped to fit into the recess 14. That is, the polyurethane foam 20 adhered along the surface shape of the test stone 11.

[0031] The polyurethane foam 20 has a high performance of entering gaps and filling voids compared to, for example, packing materials such as mortar and concrete. From this demonstration experiment, it was suggested that the polyurethane foam 20 can suppress the rolling of the stone 11 by being foamed and filling the concave portion 14 of the stone 11 and the gap 13 around the stone 11 by the foaming pressure.

[0032] Furthermore, according to the composite structure 10 described above, by using the polyurethane foam 20, the bulk and weight of the raw materials can be suppressed compared to non-foamed packing materials. In particular, when the location for suppressing the rolling of the stone 11 is an unimproved natural ground of a road or a slope where it is difficult to carry in equipment, there is a problem that it is difficult to carry in raw materials and equipment. The polyurethane foam 20 can be formed with simple equipment. For example, the equipment can be carried to the site by a trolley or manpower. Therefore, it can contribute to cost reduction in transporting the raw materials and equipment related to the formation of the polyurethane foam 20.

[0033] The polyurethane foam 20 of the present embodiment adheres to the lower surface 12 side of the stone 11. According to this configuration, the initial rolling of the stone 11 can be suppressed, and the rolling of the stone 11 can be effectively suppressed.

[0034] In the composite structure 10 of the present embodiment, a plurality of stones 11 are gathered with gaps 13 partially open. The polyurethane foam 20 is filled in the gaps 13 and adheres to each of the plurality of stones 11. Rolling is different from sliding in that each part of the plurality of stones 11 can move in different directions. For example, when the two test stones 11 shown in FIG. 4 roll, the adhesion surface of the lower test stone 11 with the polyurethane foam 20 moves upward, and the adhesion surface of the upper test stone 11 with the polyurethane foam 20 moves downward. According to the above configuration, the polyurethane foam 20 adheres to each of the plurality of stones 11, and by suppressing the rolling of the plurality of stones 11 mutually, the rolling of the plurality of stones 11 can be suppressed.

[0035] The method for suppressing the rolling of the stone 11 existing on the ground G in this embodiment is a method for suppressing the rolling of the stone 11 by attaching the polyurethane foam 20 along the surface shape of the stone 11. According to this method, the rolling of the stone 11 can be simply suppressed.

[0036] Generally, the ground consolidation method is to support the stone from below to suppress the rolling of the stone. Therefore, specialized knowledge is required for the design of the position, size, and range of the retaining wall that supports the stone. On the other hand, the method for suppressing the rolling of the stone 11 in this embodiment can form the polyurethane foam 20 attached along the surface shape of the stone 11 by injecting the polyurethane foam raw material. This is because the polyurethane foam 20 can follow the shape of the stone 11 and the ground G even if the shape of the stone 11 and the ground G is complex. That is, by changing the curing speed, raw material viscosity, cell state, etc. of the polyurethane foam 20, the polyurethane foam raw material can be spread to the recesses of the stone 11 and the depths of the gaps 13 between the stones 11. Therefore, without making a complex design like a retaining wall, by changing the molding conditions of the raw material, the polyurethane foam 20 can be attached to the stone 11 to suppress the rolling of the stone 11.

[0037] <Other Embodiments> The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The polyurethane foam may be attached to the upper surface side of the stone instead of the lower surface side. Furthermore, the range where the polyurethane foam adheres to the stone is not limited. For example, the polyurethane foam may adhere only to the surface of the stone on the lower side of the slope of the ground. The polyurethane foam may adhere to only one stone. In the above embodiment, in the stones stacked and assembled together, the polyurethane foam was attached to the lower stone, but the polyurethane foam may be attached to stones other than the lower one. Also, the polyurethane foam may be attached to the lower stone and the stone stacked on that stone. The ground may be a horizontal plane. The method for suppressing the rolling of stones may perform another arbitrary process in addition to the processes described in the embodiments.

[0038] The method for suppressing the rolling of stones may be used in combination with a rope laying method, a wire rope hanging method, a ground anchor method, etc. Furthermore, the method for suppressing the rolling of stones may be used for preventing the rolling of garden stones, stone lanterns, etc. in addition to the countermeasures against falling stones.

Explanation of Signs

[0039] 10…Composite structure 11, 11A…Stone 12…Bottom surface 13…Gap 14…Concave part 20…Polyurethane foam 21…Part 22…Nozzle 30…Plate 31…Top surface 32…Convex part

Claims

1. A stone that exists in direct contact with the ground on a sloping ground surface, and a polyurethane foam adhered along the surface shape of the stone to the lower surface of the stone, comprising: The polyurethane foam is a composite structure that fills the gap between the lower surface of the stone and the ground.

2. A method for suppressing the rolling of a stone that exists in direct contact with the ground on a sloping ground surface, the method comprising: adhering a polyurethane foam along the surface shape of the stone to the lower surface of the stone, and suppressing the rolling of the stone by filling the gap between the lower surface of the stone and the ground with the polyurethane foam.

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