Application of composite low-friction coating on outer surface of jacking pipe and jacking pipe jacking construction method based on composite low-friction coating

Abstract

The invention belongs to the technical field of underground engineering construction, and particularly relates to application of a composite low-friction coating on the outer surface of a jacking pipe, in particular to a jacking pipe jacking construction method based on the composite low-friction coating. The composite low-friction coating comprises an adhesive layer and a coating layer, wherein the adhesive layer is adjacent to the outer surface of the jacking pipe; the solid or gel lubricating layer is located on the outer side of the adhesive layer, is the outermost exposed layer of the composite low-friction coating and is used for reducing friction between the jacking pipe and a soil body in jacking construction of the jacking pipe. A traditional jacking pipe joint is improved, the composite low-friction coating is arranged on the outer surface of the jacking pipe joint, friction between the jacking pipe joint and a soil body is remarkably reduced when the jacking pipe joint is jacked in, thixotropic slurry does not need to be used for lubrication and resistance reduction, and therefore the construction link of slurry replacement is eliminated.

Description

Technical Field

[0001] The invention belongs to the technical field of underground engineering construction, and specifically relates to the application of a composite low-friction coating on the outer surface of a jacking pipe, and a jacking construction method of the jacking pipe based on the composite low-friction coating. Background Art

[0002] The construction of urban underground pipelines and underground transportation lines usually adopts two methods: open-cut construction and underground construction. Open-cut construction usually leads to urban road damage, traffic congestion, and various environmental problems such as urban ground environmental pollution and construction noise pollution, which seriously affects the daily life of urban residents. Underground construction is divided into tunnel method, pipe jacking method and shield method. Among them, pipe jacking method has been widely used in the development and utilization of urban underground space due to its advantages of economy, safety, efficiency and simplicity.

[0003] The pipe jacking method requires the pipe to be pushed into the soil. In traditional construction methods, such as Figure 1 As shown in the figure, in order to reduce the resistance between the jacking pipe and the soil during jacking, it is usually necessary to inject thixotropic mud around the jacking pipe while the jacking pipe is being pushed in to play a lubricating role. Figure 2 As shown, the thixotropic slurry needs to be pushed out and replaced with a hardenable slurry (such as cement slurry) to improve the strength and stability of the pipe jacking structure.

[0004] However, in actual engineering, thixotropic mud is often difficult to be replaced. The retained thixotropic mud forms a weak layer around the jacking pipe, thereby reducing the stability of the jacking pipe structure. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides an application of a composite low-friction coating on the outer surface of a jacking pipe, a jacking construction method based on the composite low-friction coating, and avoids the construction link of mud replacement.

[0006] Specifically, the present invention provides the following technical solutions:

[0007] Application of a composite low-friction coating on the outer surface of a top pipe, the composite low-friction coating comprising:

[0008] an adhesive layer, the adhesive layer being adjacent to the outer surface of the top pipe;

[0009] A solid or gel lubricating layer, which is located outside the adhesive layer and is the outermost exposed layer of the composite low-friction coating, is used to reduce the friction between the jacking pipe and the soil during jacking construction.

[0010] The adhesive layer and the lubricating layer of the present invention are compounded to form a composite low-friction coating, wherein the lubricating layer is the outermost exposed layer in the low-friction coating, and is a layer that can provide low friction with the soil body, thereby effectively reducing the resistance to jacking. At the same time, although there are many materials that can be used as lubrication in the field, they lack durability and strength in dealing with soil friction. The specific solid or gel lubricating layer described in the present invention can overcome this technical problem. The adhesive layer is located between the outer surface of the top pipe and the lubricating layer, which improves the adhesion between the top pipe and the lubricating layer, thereby reducing or eliminating the risk of the lubricating layer falling off. The layers in the composite low-friction coating play a complementary role, giving the composite low-friction coating good lubrication properties while giving it excellent stability in use, achieving an effect equivalent to the injection of thixotropic mud on the outside of the top pipe wall. In addition, the top pipe jacking construction method using the composite low-friction coating of the present invention can omit the injection of thixotropic mud, thereby further avoiding the construction link of mud replacement.

[0011] Preferably, when the lubricating layer is solid, the lubricating layer is a polytetrafluoroethylene plate, the surface of the polytetrafluoroethylene plate in contact with the adhesive layer is rough (more preferably the roughness Ra value is 200μm to 400μm), and the surface in contact with the soil (during the construction process) is smooth (more preferably the roughness Ra value is not more than 1.6μm); the adhesive layer contains asphalt with a thickness of 1 to 2cm.

[0012] Research has found that polytetrafluoroethylene is particularly suitable for the lubricating layer of the jacking pipe of the present invention. It not only has a low friction coefficient with the soil, but also has excellent wear resistance. The present invention further grinds one side of the polytetrafluoroethylene plate to make it rough (sandblasting can be used), and the other side is kept smooth. The rough side contacts the adhesive layer to form a better bond; the smooth side contacts the soil during the construction process and has a good lubrication effect. At the same time, research has found that the bonding performance between the reinforced concrete jacking pipe and the polytetrafluoroethylene plate is more excellent when asphalt is used as the adhesive layer.

[0013] Further preferably, the thickness of the polytetrafluoroethylene sheet is 0.3 to 0.5 cm. Studies have found that if the polytetrafluoroethylene sheet is used as a solid lubricating layer, if the thickness is too low, the polytetrafluoroethylene sheet may be damaged during grinding, and if the thickness is too large, the polytetrafluoroethylene sheet may fall off during the construction process, and if the thickness of the polytetrafluoroethylene sheet is too large, the cost will also increase.

[0014] Preferably, when the lubricating layer is in a gel state, the lubricating layer comprises a gel base and graphite sprayed on the gel base, and the gel base is between the adhesive layer and the graphite; the adhesive layer comprises an epoxy resin with a thickness of 1 to 2 cm.

[0015] The present invention adopts a gel system of sprayed graphite, so that the lubricating layer has excellent lubricating performance on the basis of taking into account certain wear resistance. In addition, even if the lubricating layer suffers from severe wear and causes the graphite on the surface to fall off, the remaining gel base itself still has a good lubricating effect and does not affect the jacking construction of the jacking pipe. At the same time, the study found that the use of epoxy resin as the adhesive layer has a more excellent bonding performance between the reinforced concrete jacking pipe and the gel lubricating layer.

[0016] Further preferably, the graphite is sprayed on the gel substrate at a ratio of 2.09 to 2.33 kg per square meter of gel substrate;

[0017] and / or, the gel substrate comprises hydrogel or liquid silicone;

[0018] And / or, the thickness of the gel substrate is 3-5 cm. Studies have shown that if the thickness of the gel substrate is too small, it is easy to wear and fail during construction, and if the thickness is too large, it is easy to be sheared and the cost is increased.

[0019] Preferably, the jacking pipe is a reinforced concrete jacking pipe. The adhesive layer disclosed in the present invention is particularly suitable for jacking pipes made of reinforced concrete and has strong bonding force.

[0020] The present invention also provides a pipe jacking construction method based on the above-mentioned composite low-friction coating, comprising the following steps:

[0021] 1) A composite low-friction coating is provided on the outer surface of the top pipe;

[0022] 2) performing jacking construction on the jacking pipe obtained in step 1);

[0023] The composite low-friction coating comprises:

[0024] an adhesive layer, the adhesive layer being adjacent to the outer surface of the top pipe;

[0025] A solid or gel lubricating layer, which is located outside the adhesive layer and is the outermost exposed layer of the composite low-friction coating, is used to reduce the friction between the jacking pipe and the soil during jacking construction.

[0026] Wherein, the preferred embodiments of the composite low-friction coating and the jacking pipe are the same as above.

[0027] Preferably, in step 2), during the jacking construction, water is injected into the outer side of the pipe wall through the grouting hole. When the soil has a high water content or the soil is loose, the present invention can directly push the jacking pipe without using thixotropic mud; when the soil has a low water content or the soil is compact, the present invention also does not need to use thixotropic mud, and water can be injected around the jacking pipe while the jacking pipe is being pushed in, thereby further reducing the jacking resistance. Generally, the more water is injected, the better the resistance reduction effect.

[0028] The beneficial effects of the present invention are at least:

[0029] 1) The application of the composite low-friction coating on the outer surface of the jacking pipe and a jacking construction method based on the composite low-friction coating provided by the present invention improves the traditional jacking pipe section, and a composite low-friction coating including an adhesive layer and a solid / gel lubricating layer is arranged on the outer surface thereof, which significantly reduces the friction between the jacking pipe section and the soil during jacking, and no thixotropic mud is needed for lubrication and drag reduction, thereby eliminating the construction link of replacing mud;

[0030] 2) The application of the composite low-friction coating provided by the present invention on the outer surface of the jacking pipe and a jacking construction method based on the composite low-friction coating, when the lubricating layer is solid, the lubricating layer is a polytetrafluoroethylene plate, and the adhesive layer is asphalt. Studies have found that polytetrafluoroethylene is particularly suitable for the lubricating layer of the jacking pipe of the present invention, which not only has a low friction coefficient with the soil, but also has excellent wear resistance. At the same time, using asphalt as the adhesive layer, the bonding performance between the reinforced concrete jacking pipe and the polytetrafluoroethylene plate is more excellent;

[0031] 3) The application of the composite low-friction coating provided by the present invention on the outer surface of the jacking pipe and a jacking construction method based on the composite low-friction coating. When the lubricating layer is in a gel state, the lubricating layer comprises a gel base and graphite sprayed on the gel base, and the adhesive layer is an epoxy resin. The present invention adopts a gel system of sprayed graphite, so that the lubricating layer has excellent lubrication performance on the basis of taking into account a certain wear resistance. In addition, even if the lubricating layer suffers from severe wear and causes the graphite on the surface to fall off, the remaining gel base itself still has a good lubrication effect and does not affect the jacking construction. At the same time, the study found that the use of epoxy resin as the adhesive layer has a more excellent bonding performance between the reinforced concrete jacking pipe and the gel lubricating layer;

[0032] 3) The application of the composite low-friction coating provided by the present invention on the outer surface of the jacking pipe and a jacking construction method based on the composite low-friction coating are particularly suitable for reinforced concrete jacking pipes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. It is obvious that the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 Schematic diagram of pipe jacking based on thixotropic mud.

[0035] Figure 2 Schematic diagram of replacing thixotropic mud after the pipe jacking construction is completed.

[0036] Among them, 1- jacking pipe joint, 2- thixotropic mud, 3- formation, 4- cement slurry.

[0037] Figure 3 It is a schematic diagram of the structure of the composite low-friction coating of the present invention, wherein 5 is an adhesive layer, 6 is a lubricating layer, and 7 is an outer wall of a reinforced concrete top pipe. DETAILED DESCRIPTION

[0038] The present invention is described below by the best embodiment. It should be known to those skilled in the art that the embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0039] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in the field or the product manual shall be followed.

[0040] Example 1

[0041] This embodiment provides a pipe jacking construction method based on a composite low-friction coating, comprising the following steps:

[0042] 1) Applying asphalt on the outer surface of the top pipe to obtain an adhesive layer with a thickness of 1.5 cm;

[0043] 2) Prepare a polytetrafluoroethylene plate with a thickness of 0.4 cm as a lubricating layer, one side of which is roughened by sandblasting (Ra value is 200 μm to 400 μm), and the other side is kept smooth (Ra value is not greater than 1.6 μm), and the rough surface is brought into contact with the adhesive layer for bonding to obtain a jacking pipe provided with a composite low-friction coating. The structural schematic diagram of the composite low-friction coating is shown in Figure 3 ;

[0044] 3) Perform jacking construction on the jacking pipe obtained in step 1).

[0045] Since PTFE has excellent wear resistance, the change in frictional resistance caused by the wear of PTFE during construction can be ignored.

[0046] Example 2

[0047] Compared with Example 1, the difference is that in step 2), during the jacking construction, water is injected into the outer side of the pipe wall through the grouting holes, and the water injection amount is 1.5 tons of water per square meter of the contact surface between the jacking pipe and the soil.

[0048] Example 3

[0049] This embodiment provides a pipe jacking construction method based on a composite low-friction coating, comprising the following steps:

[0050] 1) coating the outer surface of the top pipe with epoxy resin to obtain an adhesive layer with a thickness of 1.5 cm;

[0051] 2) A layer of hydrogel with a thickness of 4 cm is sprayed on the surface of the adhesive layer as a gel base, and graphite is sprayed on the gel base at a ratio of about 2.2 kg per square meter of the gel base, thereby obtaining a jacking pipe provided with a composite low-friction coating; wherein the hydrogel is chitosan, polyvinyl alcohol, acrylic acid and water in a weight ratio of 1:8:0.5:50.

[0052] 3) Perform jacking construction on the jacking pipe obtained in step 1).

[0053] Comparative Example 1

[0054] Comparative Example 1 uses traditional thixotropic mud, including bentonite: 10%, sodium carbonate 0.5%, sodium carboxymethyl cellulose 0.2%, and water: 89.3%.

[0055] Comparative Example 2

[0056] Compared with Example 1, the difference is that the lubricating layer is replaced by a steel pipe instead of a polytetrafluoroethylene plate (ie, the steel pipe is adhered to the outer surface of the reinforced concrete top pipe by asphalt), and the surface roughness Ra value is 15.5 μm.

[0057] Comparative Example 3

[0058] Compared with Example 1, the difference is that the material of the adhesive layer is replaced by phenolic resin instead of asphalt.

[0059] Results The polytetrafluoroethylene sheet fell off during the pipe jacking construction.

[0060] When the pipe jacking construction depth (i.e., the buried depth of the pipe jacking) is 10m, the friction resistance corresponding to each working condition is shown in Table 1.

[0061] Table 1

[0062]

[0063] Note: The weight of soil is about 19kN / m 3 .

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. The application of composite low-friction coating on the outer surface of the top pipe is characterized by: The composite low-friction coating comprises: an adhesive layer, the adhesive layer being adjacent to the outer surface of the top pipe; A solid or gel lubricating layer, which is located outside the adhesive layer and is the outermost exposed layer of the composite low-friction coating, is used to reduce the friction between the jacking pipe and the soil during jacking construction.

2. The use according to claim 1, characterized in that: When the lubricating layer is solid, the lubricating layer is a polytetrafluoroethylene plate, the surface of the polytetrafluoroethylene plate in contact with the adhesive layer is rough, and the surface in contact with the soil is smooth; the adhesive layer contains asphalt with a thickness of 1 to 2 cm; Preferably, the thickness of the polytetrafluoroethylene plate is 0.3-0.5 cm.

3. The use according to claim 1, characterized in that: When the lubricating layer is in a gel state, the lubricating layer comprises a gel base and graphite sprayed on the gel base, and the gel base is located between the adhesive layer and the graphite; the adhesive layer comprises an epoxy resin with a thickness of 1 to 2 cm.

4. The use according to claim 3, characterized in that: The graphite is sprayed on the gel substrate at a ratio of 2.09 to 2.33 kg per square meter of the gel substrate; and / or, the gel substrate comprises hydrogel or liquid silicone; And / or, the thickness of the gel substrate is 3 to 5 cm.

5. The use according to any one of claims 1 to 4, characterized in that: The jacking pipe is a reinforced concrete jacking pipe.

6. A pipe jacking construction method based on a composite low-friction coating, characterized in that: The following steps are involved: 1) A composite low-friction coating is provided on the outer surface of the top pipe; 2) performing jacking construction on the jacking pipe obtained in step 1); The composite low-friction coating comprises: an adhesive layer, the adhesive layer being adjacent to the outer surface of the top pipe; A solid or gel lubricating layer, which is located outside the adhesive layer and is the outermost exposed layer of the composite low-friction coating, is used to reduce the friction between the jacking pipe and the soil during jacking construction.

7. The pipe jacking construction method according to claim 6, characterized in that: When the lubricating layer is solid, the lubricating layer is a polytetrafluoroethylene plate, the surface of the polytetrafluoroethylene plate in contact with the adhesive layer is rough, and the surface in contact with the soil is smooth; the adhesive layer contains asphalt with a thickness of 1 to 2 cm; Preferably, the thickness of the polytetrafluoroethylene plate is 0.3-0.5 cm.

8. The pipe jacking construction method according to claim 6, characterized in that: When the lubricating layer is in a gel state, the lubricating layer comprises a gel base and graphite sprayed on the gel base, and the gel base is located between the adhesive layer and the graphite; the adhesive layer comprises an epoxy resin with a thickness of 1 to 2 cm.

9. The pipe jacking construction method according to claim 8, characterized in that: The graphite is sprayed on the gel substrate at a ratio of 2.09 to 2.33 kg per square meter of the gel substrate; and / or, the gel substrate comprises hydrogel or liquid silicone; And / or, the thickness of the gel substrate is 3 to 5 cm.

10. The pipe jacking construction method according to any one of claims 6 to 9, characterized in that: The jacking pipe is a reinforced concrete jacking pipe; And / or, in step 2), during the jacking construction, water is injected into the outer side of the pipe wall through the grouting holes.

Images