Preparation method and construction technology of seamless expansion joint material for underpass tunnel

Abstract

The application discloses a preparation method of a seamless expansion joint material for a down-penetrating tunnel and a construction process thereof; firstly, a preparation scheme of a double-modified high-viscosity high-elasticity asphalt binder is provided, and the double-modified high-viscosity high-elasticity asphalt binder is applied to the construction process of the seamless expansion joint material for the down-penetrating tunnel; the down-penetrating tunnel seamless expansion joint of the scheme is directly reserved in a concrete leveling layer above a tunnel structure, without needing to excavate a surface layer, and the down-penetrating tunnel seamless expansion joint is beautiful in appearance, saves labor and other excavation costs, and effectively avoids water seepage quality problems at joint parts; then, resin mortar and elastic body mixture are successively constructed, and two layers of asphalt concrete surface layers are continuously paved on surfaces of the resin mortar and the elastic body mixture, so that the seamless expansion joint is truly realized, and the problem of easy cracking and potholes of the surface layer material at the expansion joint is solved. The car is noiseless when driving through the down-penetrating tunnel, and the driving comfort is high, and the down-penetrating tunnel is more suitable for a large down-penetrating tunnel expansion joint with a design width of more than 400 mm, a depth of more than 100 mm and an expansion amount of less than 80 mm.

Description

Technical Field

[0001] This invention relates to a method for preparing a seamless expansion joint material for underpass tunnels and its construction process, belonging to the field of road construction technology. Background Technology

[0002] In recent years, highway construction has developed rapidly, and the number of underpasses, as an integral part of highways, has also increased dramatically. Expansion joints, often overlooked as a weak link in the design, construction, maintenance, and management of underpasses, are now gradually attracting attention and importance. The installation of expansion joints reduces relative deformation caused by temperature changes and concrete shrinkage and creep. By dividing the underpass structure into different units, stress and displacement can be released. Expansion joints have become an important auxiliary structure in underpass engineering. The quality and durability of expansion joints directly affect traffic safety, driving comfort, and vehicle speed, and also influence the service life of the underpass expansion joints.

[0003] Seamless expansion joints for underpass tunnels are increasingly widely used due to their unique structure and excellent performance characteristics. They refer to a joint structure that does not extend beyond the tunnel surface. Elastic material is filled into the expansion gap at the tunnel end and waterproof material is laid on it. Then, viscoelastic composite material is laid on the tunnel pavement layer, so that the surface pavement at the expansion joint forms a connection with other pavement parts.

[0004] In China, seamless expansion joints are mainly used on bridges with small to medium spans. There is little research on their application in underpass tunnels, and there are basically no specifications or standards for their construction. Construction relies entirely on on-site guidance from construction teams, which presents significant problems and risks.

[0005] Traditional seamless expansion joint structures between underpass tunnel segments are asphalt surface excavation type seamless expansion joints, which involve excavating the asphalt surface layer and then applying the seamless expansion joint material, and are not truly seamless expansion joints in the strictest sense. These seamless expansion joint materials are mostly elastic mixtures based on imported TST binder. TST binder is expensive, and its elastic recovery index is difficult to meet technical requirements. Furthermore, due to the limitations of the seamless expansion joint material's performance, this type of seamless expansion joint is only suitable for underpass tunnels with a design structural depth of 100mm or less and an expansion range of 50mm or less. Summary of the Invention

[0006] To address the aforementioned technical problems, the objective of this invention is to propose a method for preparing a seamless expansion joint material for underpass tunnels and its construction process.

[0007] The technical solution of this invention is achieved as follows: a construction process for a seamless expansion joint material for underpass tunnels, the specific process of which is as follows:

[0008] ① Shot blasting treatment of concrete leveling layer:

[0009] A groove is reserved at the expansion joint of the concrete leveling layer. The groove is first shot-blasted for pretreatment, and the surface laitance is ground off to expose the concrete aggregate.

[0010] ② Cleaning and drying the groove opening:

[0011] The trough opening is cleaned with a high-pressure water gun, and then the surface of the trough opening is heated and dried to remove any loose soil and particles.

[0012] ③ Install extruded polystyrene (XPS) boards:

[0013] Tightly insert the extruded polystyrene board into the expansion joint, and ensure that the installed extruded polystyrene boards are in a straight line;

[0014] ④ Apply base coat:

[0015] Stir the base coat evenly and then use a brush to apply the base coat to the entire groove.

[0016] ⑤ Mixing of resin mortar:

[0017] Rubber powder aggregate and adhesive are mixed evenly to obtain resin mortar;

[0018] ⑥ Resin mortar spreading and compaction:

[0019] Fill the groove with the mixed resin mortar from both sides of the extruded polystyrene board and compact it, controlling the flatness and ensuring that the edges are fully and densely treated.

[0020] ⑦ Apply adhesive to the bottom and sides of the upper groove:

[0021] After the resin mortar in the tank has hardened, apply a layer of molten elastic binder evenly to the bottom and sides of the upper tank opening.

[0022] ⑧ Lay steel plates on the binder:

[0023] Before the applied adhesive has hardened, cover the resin mortar with a steel plate and then cover the extruded polystyrene board with the steel plate.

[0024] ⑨ Apply adhesive again to the steel plate:

[0025] A layer of molten elastic binder is evenly applied to the steel plate;

[0026] ⑩ Mixing of elastic compressive materials:

[0027] Select crushed stone, clean it thoroughly, and heat and stir it to 200℃±10℃; preheat the double-modified high-viscosity and high-elasticity asphalt binder to 200℃±10℃ and stir it quickly and evenly; the mass ratio of the elastic mixture is: double-modified high-viscosity and high-elasticity asphalt binder / crushed stone = 1 / 5;

[0028] Spreading of elastic compound mixture:

[0029] Pour the heated and well-stirred elastic compressive material evenly into the groove and spread it in two layers. After the first layer is spread, flatten and compact it. Apply a layer of molten binder to the compacted elastic compressive material surface. Then spread the second layer, which is 3-4mm higher than the road surface.

[0030] Compaction of elastic compound mixtures:

[0031] When the surface temperature of the elastic compressive mixture cools to 90℃±5℃, use a vibratory roller to continuously compact it along the direction of the steel plate and perpendicular to the direction of the steel plate.

[0032] Topcoat sealing:

[0033] After the elastic material mixture is compacted, the next layer is sealed with adhesive. The width of the sealant extends 1-2 cm beyond both sides of the groove. Then, use a scraper to smooth the adhesive.

[0034] After sealing, the asphalt mixture is laid:

[0035] After the surface layer is sealed with adhesive, medium-grained and fine-grained asphalt mixtures are laid on top of it respectively;

[0036] Maintenance and opening to traffic:

[0037] The construction site should be cleaned up, and traffic can be opened once the asphalt mixture surface has cooled to below 50°C.

[0038] This invention also provides a method for preparing a dual-modified high-viscosity and high-elasticity asphalt binder. 18-23% of 40-mesh rubber powder is added to the base asphalt binder and heated to 170-180℃ to form a rubber asphalt binder. Then, 3-5% of SBS modifier is added and stirred at low speed for a period of time. Next, a high-speed shearing machine is used for continuous shearing to completely pulverize the SBS particles and uniformly disperse them in the rubber asphalt binder. At this point, 1.5-2.5% of solubilizer and 0.1-0.15% of stabilizer are added, and the mixture is stirred slowly for another period of time to finally prepare the dual-modified high-viscosity and high-elasticity asphalt binder.

[0039] As a preferred method, the rubber powder added to the base asphalt binder is 20% 40-mesh rubber powder; the added SBS modifier is 4%; the added solubilizer is 2%; and the added stabilizer is 0.12%.

[0040] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0041] This invention first provides a preparation scheme for a double-modified high-viscosity, high-elasticity asphalt binder, and then applies this double-modified high-viscosity, high-elasticity asphalt binder to the construction process of seamless expansion joints in underpass tunnels. The seamless expansion joint in this scheme is pre-reserved in the concrete leveling layer above the tunnel structure, eliminating the need for surface excavation. This results in an aesthetically pleasing appearance and saves on labor and other excavation costs, effectively avoiding water seepage issues at the joint. Then, resin mortar and elastic composite mixture are applied sequentially, followed by two layers of asphalt concrete surface layer, truly achieving a seamless expansion joint and solving the problem of cracking and potholes in the surface material at the expansion joint. The result is noiseless operation, high driving comfort, and is particularly suitable for large underpass tunnel expansion joints with a design width of over 400mm, a depth of over 100mm, and an expansion range of less than 80mm. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0043] Appendix Figure 1 This is a flowchart illustrating the construction process of a seamless expansion joint material for underpass tunnels as described in this invention.

[0044] Appendix Figure 2 This is a schematic diagram of the structure after construction of the seamless expansion joint material for underpass tunnels described in this invention. Detailed Implementation

[0045] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0046] The preparation method of the dual-modified high-viscosity and high-elasticity asphalt binder of the present invention is as follows: 18% of 40-mesh rubber powder is added to the base asphalt binder and heated to 170-180℃ to form a rubber asphalt binder; then 3.5% of SBS modifier is added, and the mixture is stirred at low speed for 10 minutes using a magnetic stirring device at a stirring speed of about 120 rpm; then, an FM-300 high-speed shearing machine is used to continuously shear at a speed of 5000 rpm for 30 minutes to completely crush the SBS particles and make them uniformly dispersed in the rubber asphalt; at this time, 1.5% solubilizer and 0.15% stabilizer are added, and the magnetic stirring device is adjusted to continue stirring at a slow speed for 60 minutes to finally prepare a stable dual-modified high-viscosity and high-elasticity asphalt binder containing SBS modifier and rubber powder. Example 2

[0047] The preparation method of the dual-modified high-viscosity and high-elasticity asphalt binder of the present invention is as follows: 20% of 40-mesh rubber powder is added to the base asphalt binder and heated to 170-180℃; then 4% of SBS modifier is added, and the mixture is stirred at low speed for 10 minutes using a magnetic stirring device at a stirring speed of about 120 rpm; then, an FM-300 high-speed shearing machine is used to continuously shear at a speed of 5000 rpm for 30 minutes to completely crush the SBS particles and make them uniformly dispersed in the rubber asphalt; at this time, 2% solubilizer and 0.12% stabilizer are added, and the magnetic stirring device is adjusted to continue stirring at a slow speed for 60 minutes, finally preparing a stable dual-modified high-viscosity and high-elasticity asphalt binder containing SBS modifier and rubber powder. Example 3

[0048] The preparation method of the dual-modified high-viscosity and high-elasticity asphalt binder of the present invention is as follows: 23% of 40-mesh rubber powder is added to the base asphalt binder and heated to 170-180℃; then 4.5% of SBS modifier is added, and the mixture is stirred at low speed for 10 minutes using a magnetic stirring device at a stirring speed of about 120 rpm; then, an FM-300 high-speed shearing machine is used to continuously shear at a speed of 5000 rpm for 30 minutes to completely crush the SBS particles and make them uniformly dispersed in the rubber asphalt; at this time, 2.5% solubilizer and 0.10% stabilizer are added, and the magnetic stirring device is adjusted to continue stirring at a slow speed for 60 minutes, finally preparing a stable dual-modified high-viscosity and high-elasticity asphalt binder containing SBS modifier and rubber powder.

[0049] The parameters of the prepared dual-modified high-viscosity and high-elasticity asphalt binder are shown in the table below:

[0050] It can be seen that all the indicators of the double-modified high-viscosity and high-elasticity asphalt binder meet the requirements.

[0051] like Figure 1As shown, the construction process of a seamless expansion joint material for underpass tunnels according to the present invention is as follows: personnel, materials and machinery arrive on site → site enclosure and traffic organization design → shot blasting treatment of concrete leveling layer → cleaning and drying of groove → installation of extruded polystyrene board → application of primer → mixing of resin mortar → spreading and compaction of resin mortar → application of binder to the bottom layer and sides of the upper groove → laying of steel plate on binder → application of binder again on steel plate → on-site heating and mixing of elastic compressive mixture → spreading of elastic compressive mixture in two layers → compaction when the temperature of elastic compressive mixture drops to 90℃±5℃ → sealing of surface layer → spreading of asphalt mixture after sealing → curing and opening to traffic.

[0052] The specific process of some of the steps is as follows:

[0053] ① Shot blasting treatment of concrete leveling layer:

[0054] A groove is reserved at the expansion joint of the concrete leveling layer. The groove is 70cm wide and 20cm deep. The groove is first shot-blasted and the surface laitance is ground off to expose the concrete aggregate, so as to increase its contact area with the resin mortar.

[0055] ② Cleaning and drying the groove opening:

[0056] The trench openings are cleaned with a high-pressure water gun, then heated and dried with a flamethrower to remove loose soil and particles. Some trenches in the tunnel contain a large amount of water; construction can only proceed after the trench openings have been thoroughly cleaned and dried. The bottom 10cm of the trench opening is constructed using resin mortar seamless expansion joint technology, while the top 10cm uses elastic compressive compound seamless expansion joint technology.

[0057] ③ Install extruded polystyrene (XPS) boards:

[0058] The extruded polystyrene board is 3cm thick and 1cm high. The bottom edge should be tightly attached to the Ω-shaped steel plate waterstop in the expansion joint, and the top edge should be slightly higher than the surface of the resin mortar layer by 2cm. The extruded polystyrene board should be tightly packed into the expansion joint to prevent it from moving during paving. Use a line to ensure that the installed extruded polystyrene boards are in a straight line. For irregular joints, small pieces of extruded polystyrene board can be used to fill the gaps on both sides.

[0059] ④ Apply base coat:

[0060] Stir the base coat evenly, then use a brush to apply it to the entire groove, making sure there are no gaps. After use, soak the brush in thinner to prevent it from hardening.

[0061] ⑤ Mixing of resin mortar:

[0062] Lay the mixing area on a tarpaulin, then place the mixing sheet on top. According to the ratio of 12 bags of aggregate to one set of glue, open the bags of aggregate and invert them on the sheet. Pre-mix with a shovel to break up any clumps of rubber powder. After digging a pit in the aggregate, pour the glue into a 50L bucket and mix thoroughly with a mixer. Then pour the mixture into the pre-mixed aggregate and manually stir (using a shovel and rake together) to ensure even mixing.

[0063] ⑥ Resin mortar spreading and compaction:

[0064] Fill the groove with the mixed resin mortar from both sides of the extruded polystyrene board and compact it with an electric hammer. Control the flatness and smooth it with a trowel (the trowel needs to be coated with thinner to prevent sticking). Make sure the edges are full and dense.

[0065] ⑦ Apply adhesive to the bottom and sides of the upper groove:

[0066] After the resin mortar in the tank has hardened, apply a layer of molten elastic binder evenly to the bottom and sides of the upper tank opening. When applying the material, the operation should be skillful and quick, and the coating should be completed before it solidifies. Pay attention to not leaving any gaps on the sides and ensure that the coating is applied thoroughly to prevent the binder from not bonding firmly to the tank opening and falling off, which would damage the joint.

[0067] ⑧ Lay steel plates on the binder:

[0068] Before the applied adhesive hardens, cover the resin mortar with a 3mm thick, 15cm wide steel plate. The steel plate must completely cover the extruded polystyrene board at the expansion joint, and should not be biased to one side.

[0069] ⑨ Apply adhesive again to the steel plate:

[0070] A layer of molten elastic binder is evenly applied to the steel plate.

[0071] ⑩ Mixing of elastic compressive materials:

[0072] Select hard limestone crushed stone with sharp edges and good interlocking properties. The particle size should be 5-15mm with continuous gradation, a crushing value not exceeding 25%, and a needle-like / flaky content less than 10%. The stones must be thoroughly cleaned and heated using a trailer-mounted drum-type hot recycling mixer to 200℃±10℃. The double-modified high-viscosity, high-elasticity asphalt binder should be preheated to 200℃±10℃ using a trailer-mounted self-propelled crack sealing machine. The elastic mixture ratio is: double-modified high-viscosity, high-elasticity asphalt binder / crushed stone = 1 / 5 (by mass), and then quickly and evenly mixed.

[0073] Spreading of elastic compound mixture:

[0074] Pour the heated and thoroughly mixed elastic material evenly into the trough, spreading it in two layers. The first layer should be about 5cm thick. After spreading the first layer, flatten and compact it (the flat-headed shovel must be preheated to prevent the mixture from sticking to the surface during compaction). Apply a layer of molten binder to the compacted elastic material surface. Then spread the second layer, which should be 3-4mm higher than the road surface.

[0075] Compaction of elastic compound mixtures:

[0076] When the surface temperature of the elastic compressive mixture cools to 90℃±5℃, use a small vibratory roller to compact it continuously 2-3 times along the direction of the steel plate and 1-2 times perpendicular to the direction of the steel plate (static compaction followed by vibratory compaction). The compaction should be flush with or slightly higher than the road surface. Because the elastic compressive mixture has good elasticity at room temperature, compaction must be timely to prevent insufficient compaction due to temperature drop, which could lead to premature damage.

[0077] Topcoat sealing:

[0078] After the elastic compressive mixture is compacted, a second layer of sealant is applied, extending 2cm beyond each side of the groove to enhance the elastic compressive mixture itself and its adhesion to the road surface. Carefully smooth the surface with a scraper and measure the flatness with a 3-meter straightedge. Adjustments can be made locally if unevenness is found.

[0079] After sealing, the asphalt mixture is laid:

[0080] After the surface is sealed with adhesive, medium-grained and fine-grained asphalt mixtures are laid on top of it.

[0081] Maintenance and opening to traffic:

[0082] The construction site should be cleaned up, and traffic can be opened once the asphalt mixture surface has cooled to below 50°C.

[0083] The seamless expansion joint structure of the underpass tunnel after construction is as follows: Figure 2 As shown, a concrete leveling layer 2 is located on the upper layer of the reinforced concrete tunnel floor structure 1. Both the reinforced concrete tunnel floor structure 1 and the concrete leveling layer 2 have expansion joints 3. The concrete leveling layer 2 contains a steel mesh 4. The concrete leveling layer 2 has a groove, which is located at the expansion joint 3. An extruded polystyrene board 5 is installed in the expansion joint 3, with the upper end of the extruded polystyrene board 5 extending out of the expansion joint 3. The lower layer of the groove is a 10cm thick resin mortar 6, and the upper layer is a 10cm thick elastic compressive mixture 7. A steel plate 8 is placed between the resin mortar 6 and the elastic compressive mixture 7. Finally, two layers of asphalt concrete pavement 9 are laid on the upper side of the concrete leveling layer 2 and the elastic compressive mixture 7.

[0084] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A process for constructing a seamless expansion joint material for a subgrade tunnel, characterized by, The construction process is specifically as follows: ①Concrete leveling layer shot blasting treatment: The deformation joint of the concrete leveling layer is reserved with a notch, and the notch is pretreated by shot blasting, the surface mortar is polished, and the concrete aggregate is exposed; ②Notch cleaning and drying: The notch is cleaned with a high-pressure water gun, and then the notch surface is heated and dried to make it free of dust and loose particles; ③Installation of extruded plate: The extruded plate is tightly inserted into the deformation joint, and the installed extruded plate is ensured to be in a straight line; ④Apply primer: Mix the primer evenly, and brush the primer into the entire slot with a brush; ⑤Resin mortar mixing: Mix the rubber powder aggregate and glue evenly to obtain resin mortar; ⑥Resin mortar paving and tamping: Fill the mixed resin mortar into the slot from both sides of the extruded plate and tamp it, control the flatness, and treat the edges full and dense; ⑦Apply adhesive to the upper notch bottom and side: After the resin mortar in the slot hardens, evenly apply a layer of molten elastic body adhesive to the upper notch bottom and side; ⑧Lay steel plate on adhesive: Before the applied adhesive solidifies, cover the steel plate on the resin mortar, and cover the extruded plate with the steel plate; ⑨Apply adhesive to the steel plate: Evenly apply a layer of molten elastic body adhesive to the steel plate; ⑩Mix the elastic body mixture: Select gravel, clean the gravel, and heat and stir the gravel to 200℃±10℃; heat and stir the double-modified high-viscosity high-elasticity asphalt binder to 200℃±10℃ in advance, and stir it evenly; The mass ratio of the elastic body mixture is: double-modified high-viscosity high-elasticity asphalt binder / gravel = 1 / 5; Elastic body mixture paving: Pour the heated and stirred elastic body mixture evenly into the notch, and pave it in two layers; After the first layer is paved, flatten and compact it, and then apply another layer of molten adhesive on the surface of the compacted elastic body mixture; Then pave the second layer, which is 3-4mm higher than the road surface; Elastic body mixture rolling: When the surface temperature of the elastic body mixture cools to 90℃±5℃, use a vibrating road roller to compact it in the direction of the steel plate and perpendicular to the direction of the steel plate; Surface sealing: After the elastic body mixture is compacted, the surface is sealed again, the sealing width exceeds 1-2cm on both sides of the notch, and the glue is scraped flat with a scraper; Pave asphalt mixture after sealing: After the surface is sealed, pave the medium-grained and fine-grained asphalt mixtures on it respectively; Maintenance and open traffic: Clean the construction site, and when the asphalt mixture surface cools to below 50℃, open the traffic.

2. The construction process of a seamless expansion joint material for a below- grade tunnel according to claim 1, characterized in that, The preparation method of the double-modified high-viscosity high-elasticity asphalt binder is as follows: add 18-23% of 40-mesh rubber powder to the base asphalt binder, and heat it to 170-180℃ to form a rubber asphalt binder; Then add 3-5% of SBS modifier and stir slowly for a period of time; Then use a high-speed shearing machine to continuously shear, so that the SBS particles are completely pulverized and uniformly dispersed in the rubber asphalt binder; At this time, add 1.5-2.5% of a solubilizing agent and 0.1-0.15% of a stabilizer, and continue to stir slowly for a period of time, to finally prepare the double-modified high-viscosity high-elasticity asphalt binder.

3. The construction process of a seamless expansion joint material for a down-tunnel according to claim 2, characterized in that: The rubber powder added to the base asphalt cement is 20% of 40-mesh rubber powder; the SBS modifier added is 4%; the solubilizer added is 2%; and the stabilizer added is 0.12%.

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