KR20200089383A - Method of filling void space with polyurthane foam for emergency treatment - Google Patents

Abstract

The present invention relates to a small-scale underground cavity reinforcing method for reinforcing a cavity by injecting a filling material into the underground cavity to fill the civility. The underground cavity reinforcing method uses polyurethane foam which is an expansible material as the filling material. The underground cavity reinforcing method includes the following steps of: filling the cavity by spraying the polyurethane foam to the cavity formed under the ground to expand and stiffen the same; and stacking soil on a filling part formed by the polyurethane foam to form a soil covered part. And, the underground cavity reinforcing method installs a plurality of meshes on the cavity or supports a support to further reinforce support force of the cavity.

Description

METHOD OF FILLING VOID SPACE WITH POLYURTHANE FOAM FOR EMERGENCY TREATMENT}

The present invention relates to a method of reinforcing a cavity or closing a cavity by filling a cavity connected to the surface of a cavity in the ground, particularly a cavity connected to the ground surface by a filler.

1 is a schematic view of a ground depression in a mine area. Referring to FIG. 1, when an ore such as coal or limestone is mined, a mine cavern called a “goaf” is formed in a place where the ore is mined. Over time, the cavities expand upward due to various causes, or the ground at the top of the cavities relaxes, and eventually the surface collapses.

Especially in the case of limestone mines, this problem is more serious. Limestone is easily soluble in groundwater. Groundwater is introduced and filled in the mining area of the abandoned mine, and limestone is melted by the groundwater, which increases the risk of ground collapse in the upper part of the cavity.

In addition, even if it is not a mine or an abandoned mine, cavities are often generated due to various reasons. As shown in the photo of FIG. 2, a cavity is formed in a hiking path to cause a safety accident at a considerable depth. Due to these cavities, it is necessary to reinforce the cavities to prevent safety accidents.

The size of the community varies widely. In some cases, it is localized as in the photograph of FIG. 2, but may also appear in a wide range such as subsidence. A large-scale cavity needs to perform full-scale ground stabilization construction using cement, aggregate, and grout materials, but a small-scale cavity can be reinforced at a level that can prevent safety accidents considering economic efficiency and efficiency.

In particular, small cavities are sporadically distributed, and most often occur in places where there is no infrastructure such as roads or electricity. Therefore, there is a great difficulty in transporting aggregate or grout. This is because aggregate or grout material has a large weight or volume, which makes it difficult to transport. Also, the transportation cost becomes a bigger problem than the material cost. Moreover, heavy equipment, such as a pump car, is required to fill these joints, but there is a problem that it is not easy for such heavy equipment to enter a mountainous area or a small abandoned mine.

Accordingly, a method for simply reinforcing small cavities scattered in remote areas without roads or electricity is required.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a reinforcing method capable of filling small-sized cavities formed in a ground such as a mining cavity very simply and economically using a polyurethane foam filler.

The underground joint reinforcement method using a polyurethane foam for a first aid project for preventing light damage according to the present invention for achieving the above object comprises: filling the cavity by inflating and curing a polyurethane foam in a cavity formed in the basement; And laminating soil on the filling portion formed by the polyurethane foam to form a cover portion.

In the present invention, for the stable construction of the filling portion, it is possible to further install a mesh to secure the bearing force against the external load after filling. That is, further comprising the step of installing a mesh in the cavity spaced upward from the bottom of the cavity, it is possible to form the filling portion on the mesh.

In one example of the present invention, the mesh and the filling portion may be formed in multiple stages by alternately stacking them along the vertical direction.

Further, the rim portion of the mesh may be fixed to an outer surface of the cavity, or the mesh may be completely inserted into the cavity to fix the mesh to the inner wall of the cavity.

In an example of the present invention, at least one transverse support crossing the cavity spaced apart from the bottom of the cavity is installed, and the filling portion may be formed on the support. In particular, it is preferable that the plurality of transverse supports are arranged in a direction crossing each other.

In one embodiment of the present invention, it is preferable to install at least one longitudinal support that is supported on the bottom or inner wall of the cavity and is disposed vertically, and that the filling portion is formed on the longitudinal support.

Further, in another example of the present invention, after arranging at least one transverse support disposed in the transverse direction on the longitudinal support, after installing the mesh on the transverse support, it is preferable to form the filling part on the mesh. .

In the present invention, the polyurethane foam can be hard or soft, and the hard and soft polyurethane foams are alternately stacked, or a soft polyurethane foam is first laminated and then a hard polyurethane foam is laminated thereon. Can.

In the case of injecting concrete fillings by injecting and inflating polyurethane foam, which is an expandable material, for an underground cavity that needs reinforcement, such as mining of a mine, tunnel, underground depression, underground water pipe, etc. Compared to this, there is an advantage that construction is very simple and economical.

In particular, in the case of a mountainous backcountry, there is not enough infrastructure such as a road to apply a filling method using concrete, aggregate, etc., but the polyurethane foam is light and has a small volume before expansion, so it is easy to transport and has good advantages in constructability.

In addition, the polyurethane foam is chemically stable even in an acidic and alkaline environment, and thus has the advantage of minimizing secondary environmental effects after construction even in underground spaces where groundwater is present.

In addition, the polyurethane foam has a weaker strength than concrete, but is not rapidly destroyed, and has an advantage in maintenance.

1 is a view simulating a ground depression in a mine mining cavity.
2 is a photograph of a small underground cavity.
3 is a schematic diagram of a first embodiment of the present invention.
4 is a schematic diagram of a second embodiment of the present invention.
5 is a schematic flowchart of a small-scale underground joint reinforcement method according to a third embodiment of the present invention.
6 and 7 are views for explaining the third embodiment.
8 is a view for explaining a longitudinal support and a transverse support.
9 is a view seen from above after installation of the mesh.
10 is a photograph taken a process of spraying the polyurethane foam to the cavity through a spray gun.
FIG. 11 is a photograph of a state in which a mesh is installed after filling the polyurethane foam to the middle of the lower portion of the cavity.
FIG. 12 is a photograph in which the polyurethane foam is filled on the mesh again in FIG. 11 to fill the upper portion of the cavity.

The present invention aims to fill and reinforce the underground cavity. Here, the underground cavity includes a cavity formed downward from the surface as well as a cavity extending downward again from the underground tunnel.

The above cavities can be formed for various reasons, and in the present invention, there are no separate restrictions regarding the cause of formation of cavities, but the cavities that are the objects of the present invention are mainly formed by mining mining in the abandoned mine area. to be. The cavity is either vertical or inclined. The present invention can also be applied to horizontal cavity, but since the risk of safety accident is less than that of vertical or inclined cavity, the vertical cavity or inclined cavity will be described as an example.

In addition, the present invention can be prevented from being contaminated with groundwater and aquatic ecosystems by applying a filling material to a small waterway, a wastewater pipe, and a wastewater pipe that is not managed in a closed well or a mine.

The point that the researchers of the present invention focused on reinforcing the underground cavity is ease of construction and economical efficiency. As described above, the area where the cavity is generated in the abandoned mine or underground is often located in a remote mountainous area, so it is not easy to transport the equipment. Therefore, small cavities in these areas should be able to construct with minimal equipment and logistics.

In addition, the method was devised to safely reinforce the cavity without using heavy and bulky materials such as aggregate. The solution to this problem consciousness resulted in material selection. That is, in the present invention, the cavity is filled using an expandable material. More specifically, a polyurethane foam is used in the present invention.

Polyurethane foam is produced using polyurethane and blowing agents.

Polyurethane (polyurethane) is a generic term for a urethane bond (-NHCOO-) polymer compound made of a combination of an alcohol group (OH) and an isocyanate group (NCO). Polyurethane is a kind of plastic that is tough and resistant to chemicals. It is used for electric insulators, structural materials, foam insulation materials, foam cushions, and elastic fibers. Because of its good elasticity, it is also used as a substitute for rubber.

Blowing agent (blowing agent) is a generic term for a substance that creates bubbles by mixing with plastic or rubber. Foaming agents are divided into two types: chemical blowing agents and physical blowing agents. Chemical blowing agents use the activity of isocyanate groups to react with water to form carbon dioxide to foam. Physical blowing agents form bubbles by incorporating gases or by generating heat of reaction using decomposition or evaporation type blowing agents.

Polyurethane foam is obtained by mixing two components: isocyanate (isocyanate) or methylene diphenyl diisocyanate (DMI) (component A) and polyol resin (component B). The two components are labeled A in the foam mix and A in polyol and B in polyol. When these components are mixed and mixed, they swell (Foamining), and depending on the component, the volume expands to approximately 30 times the original liquid state. Once fully expanded and dried, the polyurethane foam becomes inert, and the molecules are cross-linked to maintain their shape regardless of external environmental conditions, such as temperature changes. . In particular, the polyurethane foam has an advantage in that it is possible to enhance necessary properties such as density and strength by additionally impregnating an additive.

In the present invention, by filling and expanding the polyurethane foam in the underground cavity, it is intended to fill the cavity. Polyurethane foam is an expandable material, as described above, and expands about 30 times compared to the original volume, and is effective for cavity filling. In addition, the state of the raw material is a liquid and has the advantage of being light and easy to transport compared to aggregate or cement.

The first embodiment, which is the most basic form of the present invention, is to fill the small cavity (c) by spraying the polyurethane foam as shown in FIG. 3. If the cavity (c) is not deep, the polyurethane foam is expanded from the bottom surface of the cavity (c) to expand. The polyurethane foam filled in the cavity (c) is called the filling part (10). However, while spraying and expanding the polyurethane foam step by step, the upper surface of the filling part 10 only reaches a certain height of the upper portion of the cavity c. The filling portion 10 is filled with soil to form a cover portion 20 to completely fill the upper portion of the cavity c.

The forming of the cover portion 20 in the present invention has the purpose of preventing the polyurethane foam filling portion 10 from being exposed to the outside and harming the surrounding landscape, but is technically to prepare for a fire. Although the polyurethane foam has been described above, it has various advantages in physical properties, but may cause harmful gas when burned. This is to prevent harmful gases from being discharged from the polyurethane foam filling portion 10 in response to forest fire or the like by forming the cover portion 20 using soil. In addition, it is preferable to form a cover portion on the upper part to prevent deformation in an unexpectedly high temperature environment even if it is not a forest fire or a large fire.

In the first embodiment shown in FIG. 3, since the cavity is not deep, the cavity is completely filled with the polyurethane foam, but if the cavity is deep, it is not economical to fill the cavity completely with the polyurethane foam, and the effectiveness is not great. As described above, the present invention is not permanently completely reinforcing the cavity like a full-fledged ground reinforcement method using a grout material. More fundamentally, it is not only easy to reinforce with a grout material for small cavities in mountainous remote areas, but, if possible, it is not economical to efficiency. That is, a small cavity can be reinforced to a level that can prepare for a safety accident using polyurethane foam. This view can be applied even when the cavity is deep. That is, filling all deep cavities with polyurethane foam is inefficient and inefficient. Accordingly, in the second embodiment of the present invention, when the cavity is deep, filling is performed only from a certain height to the top, not from the bottom of the cavity. This can be easily achieved because polyurethane foam is used as the filling material. This will be described in detail.

4 shows an example of filling the highway according to the second embodiment of the present invention. As shown in FIG. 4, in the present invention, the filling portion 11 is formed by filling the polyurethane foam only from the middle portion of the cavity (c) to the upper portion, and the soil portion is stacked thereon to form the cover portion 21. The polyurethane foam is sprayed with shotcrete, and when the polyurethane foam is sprayed toward the inner wall of the cavity (c), the polyurethane foam is cured while being attached to the inner wall surface. Further, if the polyurethane foam is gradually sprayed toward the central portion of the cavity based on the polyurethane foam attached to the inner wall, the filling portion 11 can fill the cavity c without being supported on the bottom surface. Moreover, since the inner wall surface of the cavity (c) is not flat and has a curvature, the polyurethane foam expands to fill the curvature of the inner wall of the cavity (c). Accordingly, due to friction between the outer surface of the filling portion 11 and the inner wall of the cavity c, the filling portion 11 can be prevented from falling downward. In particular, in the case of the inclined cavity, as shown in FIG. 4, since the filling part 11 is inclined with respect to the direction of gravity, a part of the cavity is supported on the inner wall, so that the filling part can be more effectively prevented from being separated. Even in the case of vertical cavity, the filling part will not be easily displaced downward due to the friction between the filling part and the inner wall of the cavity. Moreover, in the case of a small-scale cavity to which the present invention is applied, the possibility that a heavy load such as a vehicle is applied to the upper portion is not large. Since it is mainly to prevent a safety accident due to a fall, the filling part only needs to support the weight of a person. Even if the polyurethane foam is not completely filled in the cavity, but partially filled as in this embodiment, the weight of approximately 100 kg may be able to withstand due to the frictional force between the polyurethane foam and the inner wall of the cavity and some supporting force.

In the first and second embodiments described above, the cavity is reinforced only by the filling part formed of the polyurethane foam and the cover part laminated on the filling part. In the third and fourth embodiments described below, a mesh is installed to facilitate the spraying of the polyurethane foam, as well as to further increase the supporting force against the load applied to the filling portion.

5 is a schematic flowchart of the third embodiment.

Referring to Figure 5, the small-scale underground joint reinforcement method according to the third embodiment, the longitudinal support 31 and the transverse support 32 are respectively installed in the cavity (c). The longitudinal support 31 is supported on the bottom surface (FIG. 6) or the inner wall (FIG. 7) of the cavity (c) as shown in FIG. 6 or FIG. 7 and is arranged in the vertical direction. Here, the vertical direction means an angle that is substantially close to the vertical direction even though it is not vertical. Only one longitudinal support 31 may be installed as shown in the figure, but may be arranged in plurality depending on the embodiment.

The lateral support 32 is coupled to the longitudinal support 31 and is arranged at an angle close to or in the horizontal direction. The 횐 direction support 32 may also be arranged only one, but a plurality of crossing each other, for example, may be arranged in a cross shape as shown in FIG. 8. Of course, the transverse supports may be arranged parallel to each other without crossing each other.

The longitudinal support 31 and the lateral support 32 are for supporting the filling part 12 disposed on the upper part. Depending on the embodiment, a plurality of longitudinal supports 31 may be installed to support the filling part 12. As in this example, the longitudinal supports 31 and the lateral support 32 together are the filling parts 12. Can support. Unlike the above-described embodiments, in the present embodiment, a support structure is installed under the filling part to more firmly support the filling part 12, and even if a load is applied on the filling part, the filling part 12 is released to the lower part. I never do that.

After the longitudinal support 31 and the lateral support 32 are installed, the mesh 40 is installed. The shape viewed from the top after the mesh 40 is installed is as shown in FIG. 9. The central portion of the mesh 40 is inserted into the cavity c, and the rim is fixed to the outside of the cavity c, that is, to the ground surface. The part inserted into the cavity c is placed on the lateral support 32. Overall, the mesh 40 is disposed along the inner wall of the cavity.

There are two reasons for installing the mesh 40. First, it is because it is easy to settle the polyurethane foam. When filling the polyurethane foam from the middle, rather than the bottom of the cavity, it must be sprayed from the inner wall surface of the cavity and extended to the central part. If the mesh 40 is installed, the polyurethane foam is attached to the mesh 40 to facilitate construction. Because it becomes. Of course, the lateral support 32 is installed on the lower portion of the mesh 40, it is also easier to spray polyurethane.

In addition, when the mesh 40 is installed and settled on the surface, the mesh acts as a support for the filling part, so that the supporting force against the load is further increased. In this embodiment, the mesh 40 is fixed to the surface using a nail 50, but depending on the embodiment, after the entire mesh is inserted into the cavity, the mesh may be fixed to the inner wall of the cavity.

In addition, although only one mesh may be installed, a plurality of meshes may be arranged spaced apart from each other along the height direction of the cavity. When the mesh is installed in multiple stages and the polyurethane foam is sprayed, the polyurethane foam and the mesh are alternately arranged. In other words, a plurality of meshes are spaced apart from each other in the filling portion. When a plurality of meshes are installed, the load-bearing capacity is reinforced as much as possible, and as the area where the polyurethane foam can settle increases, it becomes easy to spray.

As described above, after installing the longitudinal support 31 and the lateral support 32 and the mesh 40, as in the previous embodiments, the polyurethane foam is sprayed to form a filling part, and finally the soil is laminated. By forming a cover portion to finish the reinforcement for the cavity.

In the fourth embodiment, as in the third embodiment, one or a plurality of meshes are installed, but unlike the third embodiment, the support is not installed, and the installation of the mesh and installation of the filling part and the cover part are the same as described above. Therefore, detailed description will be omitted.

On the other hand, in the present invention, instead of a support, a method of filling a 3D network structure in which wires are agglomerated is first filled in a lower portion of the cavity, and then a polyurethane foam is filled thereon. The three-dimensional network structure has a large volume but has a small weight due to the large number of voids inside by loosely agglomerating fine wires. For example, a commercially available iron scrubber or a mesh structure having a density lower than that of an iron scrubber can be used. The network structure may be formed integrally, but may also be filled with a plurality of small lump-shaped network structures.

10 to 12 are pictures showing the actual cavity reinforcement process. As shown in FIG. 10, in this step, the polyurethane foam is filled to the lower region or the middle region of the cavity using a spray gun or the like, and a mesh is installed as shown in FIG. Afterwards, as shown in FIG. 12, the polyurethane foam is filled again on the mesh screen to fill the upper portion of the cavity. Later, cover and planting can be carried out.

A key feature of the present invention is that reinforcement is performed using a polyurethane foam filler in areas where reinforcement by fillers, such as abandoned mines, sinkholes, and ground depressions, is required. Polyurethane foam is very useful to replace fillers such as aggregate and cement used in existing underground joints. First, it is 1/50 times lighter than concrete, and of course, it has good portability. The fact that the road can be constructed by moving by manpower in remote areas that have not been opened has a great advantage in the simplicity and economics of construction. Furthermore, the construction is possible without opening a road for the transportation of equipment, so the damage to vegetation is minimal.

And because the volume expands to about 30 times the raw material depending on the composition ratio, it can also be applied to large cavities. Also, because it is impervious and resistant to erosion, it is excellent for application to underground cavities where groundwater is present.

In addition, polyurethane foam is very stable chemically. When eroded by acidic and alkaline environments, the effect is limited to the surface, not the structure of the final expanded foam. Since it does not react with groundwater, it has the advantage that there is no secondary environmental pollution after construction.

However, the strength of polyurethane foam is weaker than that of the existing reinforcement materials such as cement, concrete and grout. However, the problem of strength is compensated by the deformation characteristics of the polyurethane foam. That is, when the polyurethane foam is applied vertically, half of the load moves horizontally. If a load is applied beyond the compressive strength, it shows creep and gradually deforms rather than sudden destruction, thereby preventing sudden collapse.

In addition, in the present invention, in order to supplement the load bearing capacity of the polyurethane foam, a single or multiple mesh nets may be installed, and furthermore, a longitudinal support and/or a transverse support may be installed at the bottom to compensate for the load.

Above all, when using polyurethane, it is excellent in economic efficiency. In other words, compared to concrete construction, construction is possible at a cost of about 30-60%.

On the other hand, the polyurethane foam used in the present invention can be used both hard and soft. In consideration of economical efficiency, the rigid and soft polyurethane foams can be alternately spouted, or the soft polyurethane foam can be constructed on the lower side and soft on the lower side.

Unexplained reference number g denotes the ground.

c: cavity, g: ground
10, 11, 12: filling part
20, 21, 22: cover
31: longitudinal support, 32: transverse support
40: mesh
50: Nail

Claims (12)

Filling the cavity by expanding and curing it by spraying a polyurethane foam to the cavity formed in the basement; And
Small-scale underground joint reinforcement method comprising the; step of forming a cover portion by laminating the soil on the filling portion formed by the polyurethane foam. According to claim 1,
And further comprising the step of installing a mesh in the cavity spaced upward from the bottom of the cavity,
Small-scale underground joint reinforcement method, characterized in that to form the filling portion on the mesh. According to claim 2,
Small-scale underground joint reinforcement method, characterized in that the mesh and the filling part are formed in multiple stages by alternately stacking them along the vertical direction. According to claim 2,
Small-scale underground joint reinforcement method, characterized in that the rim portion of the mesh is fixed to the surface of the outside of the cavity. According to claim 2,
The mesh is completely inserted into the cavity, the mesh is a small underground joint reinforcement method, characterized in that fixed to the inner wall of the cavity. According to claim 1,
Small-scale underground joint reinforcement method, characterized in that at least one transverse support is provided to cross the cavity away from the bottom of the cavity, and the filling portion is formed on the support. The method of claim 6,
The lateral support is a small-scale underground joint reinforcement method, characterized in that arranged in a direction crossing each other in plurality. According to claim 1,
A small-scale underground joint reinforcement method characterized in that at least one longitudinal support is installed on the bottom or inner wall of the cavity and disposed in the vertical direction, and the filling part is formed on the longitudinal support. The method of claim 8,
A small-scale underground joint reinforcement method, characterized in that, after arranging at least one transverse support disposed transversely on the longitudinal port support, the filling portion is formed on the transverse support. The method of claim 9,
After installing a mesh on the lateral support, a small underground joint reinforcement method, characterized in that to form the filling portion on the mesh. According to claim 1,
The polyurethane foam may be hard or soft,
A small-scale underground joint reinforcement method comprising alternately laminating a hard and soft polyurethane foam, or laminating a soft polyurethane foam first and then laminating a rigid polyurethane foam thereon. According to claim 1,
After filling the three-dimensional network structure made of a bundle of wires at the bottom of the cavity,
A small-scale underground joint reinforcement method, characterized in that a polyurethane foam is filled on top of the three-dimensional network structure.

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