KR20220069372A - Method for filling used pipe and underground cavity - Google Patents

Abstract

The present invention relates to an underground disuse-pipe and cavity filling method in which repair can be performed by injecting filling materials into a cavity without removing road pavements, and filling materials are tightly injected and strength is guaranteed. According to the present invention, the underground disuse-pipe and cavity filling method comprises the steps of: forming a filling material injection hole connected to a cavity to be repaired; connecting an injection pipe from a storage tank in which a high fluidity filling material to be filled in the cavity is stored to the injection hole; and supplying a thickener to the end of the injection pipe so that it is mixed with the high fluidity filling material and curing the filling material.

Description

Method for filling used pipe and underground cavity

The present invention relates to a technology related to the safety and maintenance of road facilities, and to a method of reinforcing a cavity or underground pipe generated due to ground relaxation under the road by filling it with a filling material.

Various pipelines, commonly called "lifelines", such as sewage pipes, power cables, and gas pipes, are buried under the road. Pipelines may deteriorate over time or rupture due to carelessness during repair work. For example, as soil flows in through the ruptured gap in the upper part of the sewer pipe and the inflow gradually increases, a cavity is generated between the upper part of the sewer pipe and the road. Completely hollow cavities may form, but generally the soil in the ground is less dense, leaving the ground in a loosely relaxed state. The road maintains the strength of the base layer, sub-base layer, and pavement layer above a certain level. Even if the ground is relaxed, it does not collapse immediately, but eventually collapses due to repeated vehicle loads.

In addition, there are closed pipes that are no longer in use among the underground pipelines, and since the closed pipes are no longer maintained, the above problem may appear larger. Moreover, when the closed pipe itself collapses due to long-term non-use, the volume (space) occupied by the closed pipe itself acts like a sinkhole.

Cavities under the road can cause unexpected and serious damage to people and vehicles. Therefore, one of the most important points in road management is to detect an area where the ground under the road is relaxed or a cavity is formed, and to quickly reinforce it.

In the past, the open method was used to fill the cavities or closed pipes discovered through GPR exploration. That is, the repair was done by removing the pavement from the road and filling the cavity with the filling material, but this took a long time to repair, and it was very inconvenient because it involved traffic control. In addition, it is uneconomical because the pavement layer has to be installed again.

On the other hand, there is a technical issue in the common filling material.

High-fluidity fillers have the advantage of being easy to inject and easy to fill in the relaxed ground, but the filler material may be lost along cracks in the ground, especially when it is hardened by flowing into the currently used pipeline (not closed). It can be a problem. In addition, in the case of high-flow fillers, since the compressive strength is low, the bearing capacity for the load of the road on the ground may be a problem.

The low-fluidity filler does not have the problem of material loss as described above, but has a problem that it is not easy to inject and fill. In addition, the filling material from the storage tank to the injection point must be transported by pressure, but since specific gravity and viscosity are high, a high-pressure pump is required, so construction is not easy. In addition, since it is not easy to measure the pressure in the pipe, a separate pressure measurement in the pipe is also requested.

The present invention is to solve the above problems, it is possible to repair by injecting a filling material into the cavity without removing the road pavement, the filling material is tightly injected and the strength is guaranteed. There is a purpose.

On the other hand, other objects not specified in the present invention will be additionally considered within the range that can be easily inferred from the following detailed description and effects thereof.

The underground closing pipe and cavity filling method according to the present invention for achieving the above object, comprises the steps of: (a) forming a filling material injection hole connected to the cavity to be repaired; (b) connecting the injection hole from the storage tank in which the high-fluidity filler to be filled in the cavity is stored to the injection pipe; (c) supplying a thickener to the end of the injection pipe to be mixed with the high fluidity filler; and (d) curing the filling material.

According to the present invention, the injection pipe may include a main pipe extending from the storage tank, and an auxiliary injection pipe connected to the end of the main pipe to supply a thickener.

In particular, the auxiliary input pipe is disposed at an angle with respect to the main pipe and includes an inclined pipe part extending from the outside to the inside of the main pipe, and a straight pipe part extending horizontally with the main pipe at the end of the inclined pipe, the thickener is the It is preferable to be supplied horizontally with the moving direction of the filling material and mixed with the filling material.

In one example of the present invention, the distance from the point at which the thickener is discharged to the outlet of the main pipe is formed in the range of 1.5 to 2.5 m, and at the end of the main pipe, a narrow pipe part having a gradually decreasing diameter and passing through the narrow pipe part It has a constant diameter and has a discharge part inserted into the injection hole.

On the other hand, in one example of the present invention, the filler is made of 90 to 92% by weight of the filler and 8 to 10% by weight of the binder, and the filler includes fly ash and steelmaking slag, but has a median particle diameter (D50) of 20 to 30 μm It is made of fine powder, and the binder consists of 85 to 90% by weight of calcium aluminate, 3 to 5% of cement, and 5 to 10% by weight of calcium sulfoaluminate, and the filling material:water mixing ratio (weight) is 80:100 to 100 :80.

In the present invention, a high-fluidity filler is used to facilitate transport in the pipe, while a thickener is mixed with the filler just before the filler is injected into the cavity, thereby reducing the fluidity of the filler. The advantage of the filler material in the cavity is that the viscosity is increased and material loss does not occur.

In the present invention, by providing an injection pipe and an auxiliary injection pipe of a unique configuration, there is an advantage that the main material of the filler and the thickener can be mixed evenly.

In addition, in the present invention, high-strength fillers such as steelmaking slag and fly ash are used, but the particle size is limited to small, and high fluidity is made by increasing the mixing ratio of water. And calcium aluminate-based and calcium sulfoaluminate-based materials are used as binders. As a result, the filling material is hardened into a loose structure and the strength to support the lower part of the road is expressed, but it can be easily removed during underground pipeline construction. In addition, the early intensity is highly expressed, so traffic can be resumed in a short time, and there is an advantage that the period of time is shortened.

On the other hand, even if it is an effect not explicitly mentioned herein, it is added that the effects described in the following specification expected by the technical features of the present invention and their potential effects are treated as described in the specification of the present invention.

1 is a schematic view for explaining a filler injection device used in an example of the present invention.
2 is a schematic view for explaining an injection pipe.
3 is a view for explaining a process of filling a cavity under the road.
※ It is revealed that the accompanying drawings are exemplified as a reference for understanding the technical idea of the present invention, and the scope of the present invention is not limited thereby.

In the description of the present invention, if it is determined that related known functions are obvious to those skilled in the art and may unnecessarily obscure the gist of the present invention, detailed description will be omitted.

The present invention is for filling the cavity formed in the ground with a filler. Here, the cavity includes not only a completely empty state like a sinkhole, but also a case in which the ground is loose or relaxed. Also included in the cavity are closed pipes that are no longer in use underground. Since the closed underground pipe is no longer maintained, it acts the same as the cavity if the closed pipe is damaged due to corrosion or the like. In the present invention, the cavity is filled so that the facility above the cavity can be safely maintained. In particular, the cavity under the road is a major target.

Hereinafter, the underground closure and cavity filling method (hereinafter referred to as 'cavity filling method') according to the present invention will be described in more detail.

In the present invention, first, the volume of the cavity under the road detected by various exploration methods including GPR is estimated, and a filling material sufficient to completely fill the cavity is manufactured.

As shown in FIG. 1 , the injection system 100 used in the present invention includes a mixing tank 10 , a storage tank 20 , a pump 30 , a flow pressure gauge 40 , and an injection pipe 50 .

The mixing tank 10 is for preparing a filling material by mixing and stirring a plurality of materials and water. The composition of the filling material will be described later. A stirrer 11 is rotatably installed in the mixing tank 10 so that the materials and water are completely mixed.

The storage tank 20 is for temporarily accommodating the filling material formed in the mixing tank 10 . A pipe 11 is connected between the mixing tank 10 and the storage tank 20 so that the filling material is transferred. In addition, a stirrer 21 is installed in the storage tank 20 so that the filling material does not harden and maintains fluidity.

The reason for separating the mixing tank 10 and the storage tank 20 separately is to improve mixing efficiency. It may be connected directly from the mixing tank to the injection pipe, but in this case, the plurality of materials may not be completely mixed, so that the physical properties of the filling material may not be properly expressed.

An injection pipe 50 is connected to the lower portion of the storage tank 20 . A pump 30 and a flow pressure gauge 40 are installed in the injection pipe 50 . The pump 30 is for pressurizing the filling material, and the flow pressure gauge 40 is for measuring the flow rate and pressure of the filling material injected into the cavity (c). The injection pipe 50 includes a main pipe 51 connected to the storage tank 20 as shown in FIG. 2 . The main pipe 51 is formed from the storage tank 20 with a constant diameter, and at the end thereof, a narrow pipe part 52 having a gradually reduced diameter is formed, and then the discharge part 53 is again maintained with a reduced diameter constant. The discharge part 53 is bent and connected to the injection hole h as shown in FIG. 3 . The diameter of the discharge part 53 is 1/2 of the initial diameter of the main pipe 51 . For example, in this embodiment, the main pipe 51 has a diameter of 50 mm, and the discharge unit 53 has a diameter of 25 mm.

The auxiliary input pipe 54 is connected to the main pipe 51 .

The auxiliary input pipe 54 is for supplying a thickener to the filling material. The auxiliary input pipe 54 includes an inclined pipe part 55 and a straight pipe part 56 so that the thickener can be well mixed with the filling material. The inclined tube portion 55 is installed to pass through the main tube 51 from the outside, and is inclined at an acute angle (a) with respect to the main tube 51 . The straight pipe part 56 extends from the inclined pipe part 55 and is arranged coaxially and horizontally with the main pipe 51 . The diameter of the auxiliary input pipe 54 is formed about 1/10 of the main pipe 51 .

The thickener is supplied horizontally toward the center of the main tube 51 through the auxiliary input tube 54, that is, toward the flow center of the filler, so that the two materials can be well mixed. Furthermore, after the thickener is supplied through the auxiliary input pipe 54 , the main pipe 51 is connected to the narrow pipe part 52 and the discharge part 53 . And the discharge part 53 is extended to 1.8 ~ 2.5m. Since the diameter of the narrow tube 52 and the discharge portion 53 is smaller than that of the main tube, the filling material and the thickener are compressed while accelerating the mixing of the two materials. In addition, since there is a certain distance to the end of the discharge part 53, the filler and the thickener can be completely mixed before being injected into the cavity.

Separately from the preparation of the injection system 100, as shown in FIG. 3, a perforation is made for the road pavement 80 in which the base layer 81, the sub-base layer 82, and the pavement layer 83 are sequentially stacked. to form an injection hole (h). The discharge part 53 from the injection pipe 50 is inserted into the injection hole (h). In the gap between the discharge part 53 of the injection pipe 50 and the hole wall of the injection hole (h), a packer (p) is installed and sealed.

As described above, when the installation of the injection system 100 is completed, the cavity is filled by injecting the filler mixed with the thickener into the cavity, and the filler exhibits high fluidity before mixing with the thickener, making it easy to pressurize in the injection pipe When the thickener is mixed with the filler, the viscosity increases and the cavity is filled. Accordingly, all of the problems of material loss along cracks in the ground, which are pointed out as a problem of high-flow fillers, or weak strength after hardening, are all solved.

Hereinafter, the filler having the above-described characteristics will be described. The properties required for the filling material for filling the cavity under the road are as follows.

First, the fill material must have sufficient mechanical strength to support the road. However, if the long-term compressive strength is too large like the conventional cement-based filler, it may be difficult to remove the hardened filler during repair work on the life line under the cavity filling area. In addition, the low-fluidity filler, which is used as the main material for cement, is not easy to construct because high-pressure feeding is required when the filler is injected.

Therefore, while the mechanical strength and rapid hardening enough to support the road are expressed, the long-term compressive strength must be lower than that of cement. In addition, fluidity must be ensured to improve workability when filling the cavity and facilitate transport within the pipe, while, conversely, fluid loss must be prevented due to low fluidity in the cavity.

The present invention solves the above problem by adopting a method of lowering fluidity by mixing a thickener before injection into the cavity using a high fluidity filler.

The filling material used in the present invention consists of a filler and a binder. The filler can be understood as the concept of 'aggregate' in the cement field, and fly ash and steelmaking slag can be used alone or in combination. It is also possible to use a mixture of some soil and sand. However, the important point is the particle size of the filler. In this embodiment, there is a limit to the particle size of fly ash or steelmaking slag. A filler with a very small particle size in the range of 20-30 μm with a medium particle diameter (D50) is used. As mentioned earlier, the filler is a concept of aggregate and its main function is to express strength, but a small particle size is not excellent in terms of strength expression only. However, a filler having a fine particle size works advantageously because the high long-term strength has an adverse effect in the hollow filler material. When water is filled between the fillers of small particles, hardening takes place and the water evaporates, the hardening body is not dense and is formed into a coarse tissue, because this coarse tissue exhibits low long-term strength. In the past, attempts have been made to use aerated concrete as a filler in order to achieve this effect, but there is a problem in that foamed concrete loses air bubbles before hardening, or that bubble collapse occurs during long-term hardening.

In addition, in the past, steelmaking slag was not used as a filler even though it had excellent performance in strength expression. This was because of the high content of free-CaO and iron in the steelmaking slag, which caused the volume to expand during the hardening process and destroy the hardened body. . However, in the present invention, since steelmaking slag is used, but fine particle size powder is used to form a coarse structure, the destruction of the hardened body due to volume expansion of the steelmaking slag can be avoided. This is because the expansion space of the steelmaking slag is sufficiently provided because the gap between the particles is wide.

The binder is to integrate the fillers with each other, and is blended with 90 to 92% by weight of the filler and 8 to 10% by weight of the binder. In this filler, 85 to 90% by weight of a calcium aluminate-based material, 3 to 5% by weight of cement, and 5 to 10% by weight of a calcium sulfoaluminate-based material are mixed and used as the main raw material of the binder. For example, calcium aluminate-based materials such as C ₁₂ A ₇ , C ₃ A, CA, and calcium sulfoaluminate-based materials such as C ₄ A ₃ S may be used.

Conventional fillers generally use a calcium silicate-based material as a binder, but the filler used in the present invention has an important feature in that a calcium aluminate-based or calcium sulfoaluminate-based binder is used. Describe in detail.

Calcium silicate-based material (normal cement) exhibits strength as it hardens through a hydration reaction of the form shown in Reaction Formulas (1) and (2) below.

2C ₃ S + 6H → C ₃ S ₂ H ₃ + 3Ca(OH) ₂ ... Scheme (1)

2C ₂ S + 4H → C ₃ S ₂ H ₃ + Ca(OH) ₂ ... Scheme (2)

Usually, cementitious materials undergo a hydration process that reacts with water to form new minerals and hardens. Existing CLSM also obtains a hardened body of appropriate strength by the hydration reaction of cement and the pozzolan reaction between a large amount of slaked lime and amorphous silica fly ash generated during cement hydration. However, the hydration of calcium silicate-based minerals such as C ₃ S and C ₂ S, which mainly contribute to strength development during the hydration reaction of cement, takes several days to several weeks and is characterized by a slow process. Therefore, the early strength of several hours after pouring does not appear above 0.13 MPa required for the filler material. However, as the hydration reaction continues, long-term strength is highly expressed at the age of 10 days or more.

In materials for bridges, buildings, and pavements, high long-term strength is an advantage, but in filler materials, low early strength and high long-term strength act as a major weakness. In other words, if the early intensity is low, the curing time will be long, so the air will increase, and accordingly, civil complaints such as traffic control may occur. In addition, if the long-term strength is high, it is difficult to remove the filler material during pipe repair work. Due to this problem, conventionally, a calcium silicate-based binder is used, but a complementary method such as reducing the amount of addition is used, but there is a problem in that the physical properties required for the filler are insufficient.

In the present invention, both of these problems are solved by using a calcium aluminate-based binder and a calcium sulfoaluminate-based binder.

CA + H → CAH ₁₀ ... Scheme (3)

C ₁₂ A ₇ + H → C ₂ AH ₈ + AH ₃ ... Scheme (4)

C ₄ A ₃ + 8CH ₂ + 6CH + 74H 3C ₆ A ₃ H ₃₂ ... Scheme (5)

The above reaction formulas (3) and (4) show the hydration reaction of the amorphous calcium aluminate-based binder. Equation (5) shows the hydration reaction of the calcium sulfoaluminate binder. Since the above hydration reaction occurs rapidly, the early intensity is expressed high. Therefore, the long-term intensity stays at a level slightly higher than the early intensity. Compared to the calcium silicate-based binder, the calcium aluminate-based or calcium sulfoaluminate-based binder has weaker long-term strength, but acts as an advantage in the filler material.

As described above, after forming a paste by mixing water with the entire material including the filler, the binder, and additives to be described later, the filling material paste is filled in the cavity. The mixing ratio (weight) of the total material to water is 80:100 ~ The ratio is 100:80. The mixing ratio of water is very high, and this is for the purpose of increasing fluidity, and to make a sloppy hardened body by filling water between the fillers.

The filler, binder, and water described above are fed under pressure from the storage tank through the main pipe 51 of the injection pipe. The composition in which the above filler, binder and water are mixed has very good fluidity. It has a viscosity of about milk and is easily transported even with a little pressure in the main tube. In the present invention, the mixing ratio of water to the composition as described above is increased to facilitate transport in the main pipe. However, it is undesirable as the problem of the high-fluidity filler in the prior art is repeated as it is when the high-fluidity state is achieved even in the cavity. Accordingly, in the present invention, a thickener is mixed immediately before the filler is injected into the cavity to significantly reduce fluidity. Since the thickener is added just before being put into the cavity, a high pressure is not required during pressure feeding in the main pipe.

The thickener may be used in the range of 0.01 to 0.1 wt%. Fluidity is reduced by controlling the amount of thickener mixed.

In this embodiment, an acrylic thickener or a cellulose thickener may be used as the thickener. In particular, any one or a combination of polymer resins containing sodium acrylate polymer, sodium methacrylate polymer, acrylamide polymer, hydrolyzed acrylonitrile polymer, acrylic acid methacrylic acid copolymer, and acrylic acid acrylamide copolymer as a main component can be used. . Another advantage of using a thickener is that inseparability in water is improved, so that the water/material mixing ratio can be kept constant. There is always a possibility that groundwater will flow into the underground space, and accordingly, the material and water mixing ratio is changed from the design level, thereby affecting the properties of the filler. Since the thickener acts as a thickener to prevent water from entering the material, the performance of the filler can be maintained constant.

However, in the case of adding a thickener, there is an advantage in preventing material loss through control of fluidity, but a phenomenon in which the curing speed is lowered may occur. That is, since the thickener reduces the movement of water (referred to as 'free water' in terms of reaction) in the paste of the filler, the hydration reaction occurs slowly. However, in this filler material, cement mixed in an amount of 3 to 5 wt % as a binder acts as a hardening accelerator. That is, since Ca(OH) ₂ generated during C3S hydration of cement acts as a hardening accelerator, there is no need to add a separate hardening accelerator.

As described above, the present invention has two characteristics.

First, the filler, binder, and water are mixed first to form a high-fluidity filler, so it can be easily transported without applying high pressure in the injection pipe. It is possible to solve the problem of loss of filler material in the cavity. The auxiliary input pipe 54 is inserted into the main pipe 51 so that mixing between the main material and the thickener is smoothly made, but the auxiliary input pipe and the main pipe are coaxially arranged at the center point. In addition, by reducing the diameter of the injection pipe through the narrow pipe, the thickener and the filler-binder are compressed and mixed, and in this state, a certain distance to the discharge part is guaranteed, so that the filler-binder and the thickener can be mixed evenly.

In addition, in the present invention, high-strength and low-fluidity fillers such as steelmaking slag and fly ash are used, but the particle size is limited to small, and high fluidity is made by increasing the mixing ratio of water. And calcium aluminate-based and calcium sulfoaluminate-based materials are used as binders. As a result, the filling material is hardened into a loose structure and the strength to support the lower part of the road is expressed, but it can be easily removed during underground pipeline construction. In addition, the early intensity is highly expressed, so traffic can be resumed in a short time, and there is an advantage that the period of time is shortened.

The protection scope of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is added once again that the protection scope of the present invention cannot be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.

100 ... injection system
10 ... mixing tanks, 20 ... storage tanks,
30 ...pump, 40 ...flow pressure gauge
50 ... injection tube, 51 ... main tube
52 ... narrow pipe part, 53 ... discharge part
54 ... auxiliary feed pipe, 55 ... inclined pipe part
56 ... straight pipe, 80 ... road pavement
b ... cracks, c ... cavities, f ... fillers,
s ... sewer pipe, g ... ground, h ... injection hole

Claims (5)

(a) forming a filler injection hole connected to the cavity to be repaired;
(b) connecting the injection hole from the storage tank in which the high-fluidity filler to be filled in the cavity is stored to the injection pipe;
(c) supplying a thickener to the end of the injection pipe to be mixed with the high fluidity filler; and
(d) the step of curing the filling material; underground closed pipe and cavity filling method comprising the. The method of claim 1,
The injection pipe, the underground closing pipe and cavity filling method, characterized in that it comprises a main pipe extending from the storage tank, and an auxiliary injection pipe connected to the end of the main pipe to supply a thickener. 3. The method of claim 2,
The auxiliary input pipe is disposed at an angle with respect to the main pipe and includes an inclined pipe part extending from the outside to the inside of the main pipe, and a straight pipe part extending horizontally with the main pipe at the end of the inclined pipe,
The thickener is supplied horizontally with the progress direction of the filling material and mixed with the filling material. 4. The method of claim 3,
The distance from the point where the thickener is discharged to the outlet of the main pipe is formed in the range of 1.8 to 2.5 m,
An underground closed pipe and cavity filling method, characterized in that the end of the main pipe includes a narrow pipe part having a gradually decreasing diameter, and a discharge part having a constant diameter passing through the narrow pipe part and being inserted into the injection hole. The method of claim 1,
The filling material consists of 90 to 92 wt% of a filler and 8 to 10 wt% of a binder,
The filler includes fly ash and steelmaking slag, but is made of fine powder having a median particle diameter (D50) of 20 to 30 μm,
The binder consists of 85 to 90% by weight of calcium aluminate, 3 to 5% of cement, and 5 to 10% by weight of calcium sulfoaluminate,
The filling material: water mixing ratio (weight) is 80: 100 ~ 100: 80, characterized in that the underground closed pipe and cavity filling method.

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