3D printing concrete construction method for arched open cut tunnel

Abstract

The invention provides a 3D printing concrete construction method for an arched open cut tunnel, which comprises the following steps of: S1, carrying out survey lofting, and excavating after determining a construction area; the method comprises the following steps of S1, carrying out base layer concrete spraying through 3D printing equipment, S3, carrying out inverted arch pouring after the base layer concrete reaches the set strength, S4, moving a steel bar trolley to a designated position along a steel rail and then fixedly connecting a grid arch frame corresponding to a tunnel main body with an inverted arch frame, and S5, carrying out lining concrete printing through the 3D printing equipment. An outer-layer reinforcing mesh is bound above the lining concrete; s6, waterproof coatings are sprayed on the surfaces of the waterproof cloth and the outer lining concrete, so that the waterproof cloth and the waterproof coatings are connected into a whole; and S7, base layer concrete corresponding to the tunnel body is sprayed on the surface of the waterproof coating. The 3D printing equipment is applied to multiple construction links such as base layer concrete spraying, lining concrete printing and outer lining concrete printing, the automation degree is high, and the labor demand is effectively reduced.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction technology, specifically relating to a 3D printing concrete construction method for arched open-cut tunnels. Background Technology

[0002] Arched open-cut tunnels, as a common tunnel structure, are widely used in mountainous areas and shallow-buried sections with complex terrain. Their main function is to resist geological disasters such as landslides and rockfalls, protecting the safety of the tunnel's main structure. Traditional arched open-cut tunnel construction often employs formwork support and on-site concrete pouring. With the rapid development of 3D printing technology in the construction field, 3D-printed concrete technology, with its advantages of high automation, high construction efficiency, high material utilization, and high molding precision, is gradually being applied to tunnel construction. However, a mature technical system for 3D-printed concrete construction methods for arched open-cut tunnels has not yet been formed. Existing construction methods suffer from problems such as poor coordination between pre- and post-construction phases and inadequate tunnel waterproofing, making it difficult to meet the construction quality and safety requirements of arched open-cut tunnels.

[0003] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a method for constructing arched open-cut tunnels using 3D-printed concrete.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for constructing arched open-cut tunnels using 3D-printed concrete includes: Step S1: Conduct surveying and setting out to determine the construction area before excavation; Step S2: After installing the invert arch frame corresponding to the invert arch, use 3D printing equipment to spray the base concrete corresponding to the invert arch, spray a waterproof coating on the surface of the base concrete, and lay waterproof cloth with the waterproof coating on both sides of the invert arch. Step S3: After the base concrete reaches the set strength, the invert arch is poured. The two ends of the invert arch frame extend upwards to the upper surface of the invert arch. After the invert arch reaches the preset strength, the steel rails are installed. Step S4: After moving the steel bar trolley along the rail to the designated position, fix the corresponding grid arch frame and invert arch frame of the tunnel body, fix the adjacent grid arch frames with longitudinal bars, and tie the inner layer steel mesh with the longitudinal bars as the reference. Step S5: Print the inner lining concrete using a 3D printing device. After the inner lining concrete reaches the specified strength, tie the outer steel mesh on top of the inner lining concrete. Step S6: Print the outer lining concrete using a 3D printing device. After the outer lining concrete has been cured to the set strength, the soil on both sides of the invert arch and the upper edge of the base concrete are lifted to expose the waterproof cloth. The edge of the waterproof cloth is attached to the surface of the outer lining concrete, and a waterproof coating is sprayed on the surface of the waterproof cloth and the outer lining concrete to connect the waterproof cloth and the waterproof coating into a whole. Step S7: Apply the base concrete corresponding to the tunnel body to the surface of the waterproof coating.

[0006] Preferably, the inner steel mesh is provided with inverted J-shaped connecting bars, and the outer steel mesh is connected to the inner steel mesh through the J-shaped connecting bars.

[0007] Preferably, the construction joints of the base concrete, outer lining concrete, and inner lining concrete are staggered in the tunnel mileage direction, and a waterproof coating is sprayed at the construction joints of the outer lining concrete and inner lining concrete. The base concrete is C30 concrete; the outer lining concrete is water-repellent concrete; and the inner lining concrete is impermeable concrete.

[0008] Preferably, the tunnel is constructed in sections, with each three sections forming a cycle, for the separate construction of initial shotcrete, outer lining concrete, and inner lining concrete.

[0009] Preferably, the rebar trolley includes: The main frame has an arched template corresponding to the inner wall of the tunnel above it, and traveling wheels are connected to the bottom of the main frame through a lifting cylinder; The two side wall templates are respectively hinged to both sides of the arch template, and the lower part of the side wall template is provided with a folding hydraulic cylinder corresponding to the main frame; Support blind holes are provided, and multiple arrays of support blind holes are distributed on the outer surface of the arch template. The grid arch frame is supported in the support blind holes by support ribs.

[0010] Preferably, the support rib is T-shaped, and a rubber plug is detachably installed inside the support blind hole.

[0011] Preferably, the 3D printing equipment includes: A traveling frame straddles the outside of the tunnel, with bottom wheels at the bottom and two crossbeams extending laterally along the tunnel above it. A drive frame is provided, which moves along the two crossbeams via drive wheels. A lifting mechanism is provided in the middle of the drive frame, and a mechanical arm is provided at the lower end of the lifting mechanism. A nozzle is provided on the mechanical arm, and the nozzle is connected to a concrete pump.

[0012] Preferably, the lifting mechanism includes multiple square frames that are slidably assembled along the longitudinal direction, and a drive rod is provided between any two adjacent square frames and between the outermost square frame and the drive frame.

[0013] Beneficial effects: Applying 3D printing equipment to multiple construction stages, including base concrete spraying, inner lining concrete printing, and outer lining concrete printing, results in a high degree of automation, effectively reducing labor requirements and the labor intensity of construction workers. The adoption of a dual waterproofing system of "waterproof coating + waterproof cloth + waterproof coating" effectively improves the tunnel's waterproof performance, preventing rainwater and groundwater from seeping into the tunnel and damaging its structure, thus extending the tunnel's service life. The segmented construction and three-stage-one-cycle construction mode ensures the orderly connection of each construction stage and shortens the construction cycle. Attached Figure Description

[0014] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein: Figure 1 This is a construction diagram shown in a specific embodiment of the present invention.

[0015] In the diagram: 1. Walking frame; 2. Grid arch frame; 3. Main frame; 4. Arch top formwork; 5. Side wall formwork; 6. Supporting reinforcement; 7. Square steel cage; 8. Lifting cylinder; 9. Folding cylinder; 10. Drive frame; 11. Lifting mechanism; 12. Crossbeam; 13. Robotic arm; 14. Nozzle. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0017] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0018] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0019] like Figure 1 As shown, a 3D printed concrete construction method for an arched open-cut tunnel includes: Step S1, conducting surveying and setting out, using high-precision measuring instruments to accurately measure parameters such as the plane position, elevation, and slope of the tunnel construction area, determining the boundary range and excavation depth of the construction area, carrying out excavation work in the construction area according to design requirements, strictly controlling the excavation slope and excavation progress during the excavation process, and cleaning and leveling the excavation surface after the excavation is completed.

[0020] Step S2: First, install and fix the invert arch frame corresponding to the invert arch according to the design position. The invert arch frame can be made of I-beams or grid structure. After installing the invert arch frame corresponding to the invert arch, temporarily fix the invert arch frame. Use 3D printing equipment to spray the base concrete. After the base concrete has initially set, spray a waterproof coating on its surface. Before the waterproof coating solidifies, lay waterproof cloth that adheres to the waterproof coating on both sides of the invert arch.

[0021] The waterproof coating is an acrylic waterproof spray film with a thickness of not less than 3mm. Before spraying the waterproof coating, the surface of the base concrete must be cleaned with a blower to remove dust, debris and loose parts, ensuring that the waterproof coating adheres tightly to the initial sprayed concrete.

[0022] Step S3: After the base concrete is sprayed, it is cured to a set strength (usually above 70% of the design strength). Once the base concrete reaches the set strength, the invert arch is poured. After pouring, the surface of the invert arch is smoothed and polished. The two ends of the invert arch frame extend upwards from the upper surface of the invert arch for subsequent connection with the grid arch frame 2. The invert arch is cured to a preset strength (usually above 80% of the design strength). After the invert arch reaches the preset strength, steel rails are installed as a walking foundation to support the movement of the subsequent rebar trolley.

[0023] Step S4: After the steel rail is installed, the steel bar trolley is moved along the steel rail to the designated position and the corresponding grid arch frame 2 of the tunnel body is fixedly connected to the invert arch frame. The adjacent grid arch frames 2 are fixedly connected by longitudinal bars, and the inner steel mesh is tied with the longitudinal bars as the reference. The connection method is welding or mechanical connection. After the longitudinal bars are installed, the inner steel mesh is tied with the longitudinal bars as the reference.

[0024] In step S5, the steel bar trolley is equipped with a template corresponding to the inner lining concrete. After the inner layer steel mesh is tied, the inner lining concrete is printed by a 3D printing device. The 3D printing device operates according to the preset printing path and parameters. After the inner lining concrete reaches the specified strength, it is cured to the specified strength (usually more than 70% of the design strength). The outer layer steel mesh is tied on top of the inner lining concrete.

[0025] Step S6: After the outer steel mesh is tied, the outer lining concrete is printed using 3D printing equipment. After the outer lining concrete has cured to the set strength (usually more than 80% of the design strength), the soil on both sides of the invert arch and the upper edge of the base concrete are lifted to expose the previously laid waterproof cloth. During the lifting process, avoid damaging the waterproof cloth. Fold the edge of the waterproof cloth upward and attach it to the surface of the outer lining concrete. During the attachment process, ensure that the waterproof cloth is wrinkle-free, undamaged, and without gaps. After the attachment is completed, fix the edge of the waterproof cloth. The waterproof cloth can be fixed by adhesive bonding. Then, spray a waterproof coating on the surface of the waterproof cloth and the outer lining concrete to connect the waterproof cloth and the waterproof coating into a whole, forming a complete waterproof system and improving the waterproof performance of the tunnel.

[0026] Step S7: After the waterproof coating is applied and cured, the base concrete corresponding to the tunnel structure is sprayed onto the surface of the waterproof coating to form a seal around the tunnel. Spraying is performed using 3D printing equipment or specialized spraying equipment. After spraying, the surface is smoothed to lay the foundation for subsequent tunnel ancillary structure construction. The base concrete is C30 concrete; the outer lining concrete is water-repellent concrete; and the inner lining concrete is impermeable concrete. A hardener is added to both the outer and inner lining concrete to ensure rapid setting.

[0027] In one optional embodiment, the inner steel mesh is provided with inverted J-shaped connecting bars, and the outer steel mesh is connected to the inner steel mesh through the J-shaped connecting bars. One end of the connecting bar is fixedly connected to the inner steel mesh (by welding or binding), and the other end (the bent end) is fixedly connected to the outer steel mesh. The inverted J-shaped connecting bars achieve a firm connection between the inner and outer steel meshes, ensuring that they work together to bear the load, thereby improving the overall strength and stability of the steel reinforcement skeleton. During the printing of the inner lining concrete, its thickness is less than the length of the connecting bar, thus ensuring that the bent end of the connecting bar extends out of the inner lining concrete.

[0028] Furthermore, the construction joints of the base concrete, outer lining concrete, and inner lining concrete are staggered along the tunnel mileage direction. A waterproof coating is sprayed at the construction joints of the outer and inner lining concrete. This staggered arrangement of construction joints effectively avoids structural weaknesses caused by concentrated construction joints, improving the overall integrity and load-bearing capacity of the tunnel structure. The waterproof coating applied to the construction joints enhances their waterproofing performance, preventing rainwater and groundwater from seeping into the tunnel through the joints.

[0029] The tunnel is constructed in sections, with each cycle consisting of three sections, for the separate application of initial shotcrete, outer lining concrete, and inner lining concrete. Segmented construction effectively improves construction efficiency, ensures the orderly connection between the initial shotcrete, outer lining concrete, and inner lining concrete processes, avoids conflicts in construction procedures, shortens the construction period, and simultaneously ensures the quality of each construction stage, thereby enhancing the overall integrity of the tunnel structure.

[0030] In one optional embodiment, the rebar trolley includes a main frame 3, side wall formwork 5, and supporting blind holes. The main frame 3 is made of welded steel sections. Above the main frame 3 is an arched formwork 4 corresponding to the inner wall of the tunnel. The curvature and dimensions of the arched formwork 4 match the tunnel lining. The formwork is located inside the grid arch frame 2. Below the main frame 3, there are traveling wheels connected to a lifting cylinder 8. The traveling wheels are adapted to the steel rails and can drive the rebar trolley to move along the steel rails to realize the operation of different construction segments. The traveling wheels are connected to a drive motor. The elevation of the main frame 3 can be adjusted by the lifting cylinder 8, so that demolding is carried out by gravity when the lifting cylinder 8 is retracted.

[0031] Two side wall templates 5 are hinged to both sides of the arch template 4. A folding cylinder 9 corresponding to the main frame 3 is located in the lower part of each side wall template 5. One end of the folding cylinder 9 is hinged to the side wall template 5, and the other end is hinged to the main frame 3. The angle of the side wall template 5 can be adjusted by extending and retracting the folding cylinder 9. The folding cylinder 9 also folds the side wall template 5 in conjunction with the lifting cylinder 8, ensuring that the side wall template 5 does not collide with the tunnel floor during the lowering of the main frame 3. Support blind holes are provided on both the arch template 4 and the side wall template 5. Multiple support blind holes are arrayed on the outer surface of the templates, and the size and spacing of the support blind holes are adapted to the support requirements of the grid arch frame 2. The grid arch 2 is supported in the support blind hole by the support rib 6. The support rib 6 is fixedly connected to the grid arch 2 to ensure the grid arch 2 is accurately positioned. Furthermore, the support rib 6 is T-shaped. One end of the T-shaped support rib 6 is inserted into the support blind hole, and the other end is fixedly connected to the grid arch 2. The T-shaped structure can enhance the support stability of the support rib 6. A rubber plug is installed in the support blind hole in a detachable manner. Specifically, a rubber plug is installed in the support blind hole where the support rib 6 is not set, so as to ensure that the poured concrete will not enter the support blind hole.

[0032] In another optional embodiment, the 3D printing equipment includes a walking frame 1 and a drive frame 10. The walking frame 1 straddles the outside of the tunnel and is welded from structural steel or I-beams. The bottom of the walking frame 1 is provided with bottom wheels, which are connected to a drive motor, so that it can move along the steel rails on the ground. Above the walking frame 1, there are two crossbeams 12 extending laterally along the tunnel. The two crossbeams 12 are parallel to each other, and the spacing is adapted to the size of the drive frame 10. The drive frame 10 moves along the two crossbeams 12 by drive wheels. Specifically, the crossbeams 12 are provided with dovetail grooves extending along their length direction, and the drive frame 10 is provided with sliders that slide along the dovetail grooves. The drive frame 10 moves along the two crossbeams 12 by drive wheels. The drive wheels can be gears connected to the drive motor. The crossbeams 12 are provided with racks parallel to the dovetail grooves. The gears mesh with the racks to drive the drive frame 10.

[0033] A lifting mechanism 11 is provided in the middle of the drive frame 10. A robotic arm 13 is provided at the lower end of the lifting mechanism 11. A nozzle 14 is provided on the robotic arm 13. The lifting mechanism is used to adjust the height of the robotic arm 13 and the nozzle 14. The robotic arm 13 can achieve multi-degree-of-freedom rotation and movement, which facilitates the adjustment of the angle and position of the nozzle 14. The specifications of the nozzle 14 are adapted to the concrete printing requirements. The nozzle 14 is connected to a concrete pump. The concrete pump delivers the mixed concrete to the nozzle 14, which sprays or prints it to the designated position.

[0034] In this embodiment, the lifting mechanism 11 includes multiple square frames that slide longitudinally. A drive rod is provided between any two adjacent square frames and between the outermost square frame and the drive frame 10. The square frames are welded from channel steel or square steel. In this embodiment, three square frames are nested together and can slide longitudinally, allowing the lifting mechanism 11 to extend and retract while reducing its height. The drive rods are hydraulically or electrically driven. The extension and retraction of the drive rods causes the square frames to slide, thereby adjusting the height of the robotic arm 13.

[0035] In another optional embodiment, in step S2, the two ends of the invert arch frame extend upwards beyond the upper surface of the invert arch concrete. Square steel cages 7 extending along the tunnel mileage direction are provided on both sides of the invert arch. The square steel cages 7 are made of steel reinforcement binding. The invert arch frame is fixedly connected to the square steel cages 7 (either by welding or binding). The square steel cages 7 enhance the support stability of the invert arch frame and provide reliable support points for the connection of the grid arch frame 2. A connection station for connecting the grid arch frame 2 is provided on the upper surface of the square steel cage 7. The connection station is a square steel plate adapted to the grid arch frame 2. The square steel plate is made of high-strength steel plate, and its dimensions are adapted to the end dimensions of the grid arch frame 2. The square steel plate is fixedly connected to the upper surface of the square steel cage 7 (by welding). An adjusting shim is detachably provided between the square steel plate and the corresponding grid arch frame 2. The thickness of the adjusting shim can be adjusted according to actual installation requirements. The adjusting shim can compensate for dimensional deviations during installation, ensuring installation accuracy.

[0036] In this embodiment, a controller is installed on the rebar trolley. The controller is communicatively connected to the lifting cylinder 8, the folding cylinder 9, and each drive motor. A sensing module is installed on the controller. Multiple calibration points are set between the rails of the rebar trolley. The calibration points are located using high-precision measuring instruments. The tunnel lining concrete design parameters at each point are confirmed through measurement. The sensing module obtains the lining concrete design parameters by sensing the position information of the calibration points, thereby allowing the controller to adjust the position and angle of the rebar trolley in real time. The controller is a PLC controller, and the sensing module uses NFC sensing elements, laser sensors, or Hall effect sensors to quickly and accurately sense the calibration point position information. The controller controls the actions of the folding cylinder 9 and the lifting cylinder 8 in real time based on the sensed information. The calibration points are preferably NFC sensing elements. NFC, also known as Near Field Communication (NFC), is a short-range, high-frequency wireless communication technology that allows contactless point-to-point data transmission between electronic devices. The corresponding construction design parameters can be obtained by reading the data.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall be within the scope of protection of the pending claims of the present invention.

Claims

1. A method for constructing arched open-cut tunnels using 3D-printed concrete, characterized in that, include: Step S1: Conduct surveying and setting out to determine the construction area before excavation; Step S2: After installing the invert arch frame corresponding to the invert arch, use 3D printing equipment to spray the base concrete corresponding to the invert arch, spray a waterproof coating on the surface of the base concrete, and lay waterproof cloth with the waterproof coating on both sides of the invert arch. Step S3: After the base concrete reaches the set strength, the invert arch is poured. The two ends of the invert arch frame extend upwards to the upper surface of the invert arch. After the invert arch reaches the preset strength, the steel rails are installed. Step S4: After moving the steel bar trolley along the rail to the designated position, fix the corresponding grid arch frame and invert arch frame of the tunnel body, fix the adjacent grid arch frames with longitudinal bars, and tie the inner layer steel mesh with the longitudinal bars as the reference. Step S5: Print the inner lining concrete using a 3D printing device. After the inner lining concrete reaches the specified strength, tie the outer steel mesh on top of the inner lining concrete. Step S6: Print the outer lining concrete using a 3D printing device. After the outer lining concrete has been cured to the set strength, the soil on both sides of the invert arch and the upper edge of the base concrete are lifted to expose the waterproof cloth. The edge of the waterproof cloth is attached to the surface of the outer lining concrete, and a waterproof coating is sprayed on the surface of the waterproof cloth and the outer lining concrete to connect the waterproof cloth and the waterproof coating into a whole. Step S7: Apply the base concrete corresponding to the tunnel body to the surface of the waterproof coating.

2. The method for constructing arched open-cut tunnels using 3D-printed concrete according to claim 1, characterized in that, The inner layer of steel mesh is provided with inverted J-shaped connecting bars, and the outer layer of steel mesh is connected to the inner layer of steel mesh through the J-shaped connecting bars.

3. The method for constructing arched open-cut tunnels using 3D-printed concrete according to claim 1, characterized in that, The construction joints of the base concrete, outer lining concrete and inner lining concrete are staggered in the tunnel mileage direction, and a waterproof coating is sprayed at the construction joints of the outer lining concrete and inner lining concrete. The base layer concrete is C30 concrete; the outer lining concrete is water-repellent concrete; and the inner lining concrete is impermeable concrete.

4. The 3D-printed concrete construction method for arched open-cut tunnels according to claim 1, characterized in that, The tunnel is constructed in sections, with each cycle consisting of three sections, for the separate application of initial shotcrete, outer lining concrete, and inner lining concrete.

5. The 3D-printed concrete construction method for arched open-cut tunnels according to claim 1, characterized in that, The steel reinforcement trolley includes: The main frame has an arched template corresponding to the inner wall of the tunnel above it, and traveling wheels are connected to the bottom of the main frame through a lifting cylinder; The two side wall templates are respectively hinged to both sides of the arch template, and the lower part of the side wall template is provided with a folding hydraulic cylinder corresponding to the main frame; Support blind holes are provided, and multiple arrays of support blind holes are distributed on the outer surface of the arch template. The grid arch frame is supported in the support blind holes by support ribs.

6. The 3D-printed concrete construction method for arched open-cut tunnels according to claim 5, characterized in that, The support rib is T-shaped, and a rubber plug is detachably installed inside the blind hole of the support.

7. The method for constructing arched open-cut tunnels using 3D-printed concrete according to claim 1, characterized in that, 3D printing equipment includes: A traveling frame straddles the outside of the tunnel, with bottom wheels at the bottom and two crossbeams extending laterally along the tunnel above it. A drive frame is provided, which moves along the two crossbeams via drive wheels. A lifting mechanism is provided in the middle of the drive frame, and a mechanical arm is provided at the lower end of the lifting mechanism. A nozzle is provided on the mechanical arm, and the nozzle is connected to a concrete pump.

8. The method for constructing arched open-cut tunnels using 3D-printed concrete according to claim 7, characterized in that, The lifting mechanism includes multiple square frames that are slidably assembled along the longitudinal direction, and a drive rod is provided between any two adjacent square frames and between the outermost square frame and the drive frame.

9. The method for constructing arched open-cut tunnels using 3D-printed concrete according to claim 1, characterized in that, In step S2, the two ends of the invert arch frame extend upwards to the upper surface of the invert arch concrete. Square steel cages extending along the tunnel mileage direction are provided on both sides of the invert arch. The invert arch frame is fixedly connected to the square steel cages. A connection station for connecting the grid arch frame is provided on the upper surface of the square steel cages.

10. The method for constructing arched open-cut tunnels using 3D-printed concrete according to claim 9, characterized in that, The connecting station is a square steel plate adapted to the grid arch frame. An adjustment pad is detachably provided between the square steel plate and the corresponding grid arch frame. The grid arch frame is fixed to the connecting station by bolts.

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