3D printing concrete retaining wall based on automatic feedback mechanism and construction method thereof

Abstract

The invention provides a 3D printing concrete retaining wall based on an automatic feedback mechanism, and the 3D printing concrete retaining wall comprises a layered printing structure which is formed by stacking multiple layers of concrete materials layer by layer, and the thickness of each layer is 8-15 mm; the retaining wall base is a C30 concrete base; a special-shaped optimized path is adopted, and the maximum stress concentration coefficient in the retaining wall is achieved on the basis of a printing track generated through finite element stress analysis; the composite material protection layer is arranged on the surface of the layered printing structure, the composite material protection layer comprises uniformly distributed fiber reinforced materials, and the adding proportion of a fiber composite material in the 3D printing concrete is 0.5%-1%; the drainage pipeline is arranged in the layered printing structure and the composite material protection layer; and the embedded sensor network is distributed in a key stress area in the retaining wall and is used for monitoring stress, temperature and humidity data in real time. According to feedback dynamic adjustment in the path printing process, the crack occurrence rate is reduced, material waste is reduced, manual intervention is reduced through automatic control, and the construction efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent construction of road retaining walls, and in particular to a 3D printed concrete retaining wall based on an automatic feedback mechanism and a construction method thereof. Background Art

[0002] Traditional retaining wall construction methods usually use cast-in-place concrete or prefabricated components, which have problems such as long construction period, high material waste, and high labor costs. In recent years, the application of 3D printing technology in the construction field has gradually increased, but its application in retaining wall construction still faces many difficulties: 1. Comparative document CN116777898B proposes a method for measuring cracks in the construction process of 3D printed retaining walls based on AFFormer, and its protection rights are: "Its steps include: using a data set with annotation information to train the AFFormer neural network to obtain a binary image segmentation result of the cracks; setting a connectivity threshold, deleting the connected domains with a pixel number less than the connectivity threshold through connected domain denoising, and obtaining a denoised crack skeleton image; using morphological processing to refine the cracks in the denoised crack skeleton image to obtain the refined cracks, and using the Canny edge detection algorithm to calculate the grayscale gradient of the crack binary image for the denoised crack skeleton image, find the image edge and obtain the crack edge map, and perform pixel-by-pixel logical AND operations on the edge map obtained by the Canny edge detection and the refined cracks; using the eight-direction search method to calculate the crack pixel width size, and then obtain the actual crack width size. The accuracy of segmentation and prediction is greatly improved, and real-time and high-precision measurement can be achieved." However, it relies on post-image processing and cannot adjust printing parameters in real time.

[0003] 2. Comparative document CN114856694B proposes a filling retaining wall and construction method based on an integrated flexible frame, and its protection authority is: "After the mining is completed, the construction method determines the position of the filling retaining wall at the junction of the mining area and the mining area connecting road, obtains the mining area contour data, and reconstructs the digital mining area contour surface, and then designs the filling retaining wall integrated flexible frame including a mesh wall structure, a bottom fixed structure and a supporting structure according to the reconstructed digital mining area contour surface. The cross-section of the mesh wall structure is a right-angled trapezoid, and the wall surface of one side of the filling retaining wall in the filling body is a right-angled trapezoidal inclined wall surface; the integrated flexible frame is 3D printed and packaged, and then transported to the site, and fixed on the mining area floor after unfolding; waste rock is then thrown into the mesh wall structure, and filter cloth is laid and fixed on the outer surface of the inclined wall surface to obtain a filling retaining wall. The present invention is simple and quick to construct, with low labor intensity for workers, and the on-site waste rock can be effectively utilized, thereby improving the construction efficiency of the filling retaining wall." However, it has not been optimized for the stress concentration problem of special-shaped retaining walls.

[0004] Therefore, a 3D printed concrete retaining wall based on an automatic feedback mechanism and a construction method thereof are proposed to solve the above problems. Summary of the invention

[0005] In view of the above problems, the present invention proposes a 3D printed concrete retaining wall based on an automatic feedback mechanism, comprising: Layered printing structure, formed by stacking multiple layers of concrete materials layer by layer, with each layer being 8-15mm thick; A retaining wall base, wherein the retaining wall base is a C30 concrete base; Special-shaped optimization path, based on the printing trajectory generated by finite element stress analysis, maximizes the stress concentration factor inside the retaining wall ; A composite material protective layer is provided on the surface of the layered printed structure. The composite material protective layer contains evenly distributed fiber reinforcement materials. The addition ratio of fiber composite materials in 3D printed concrete is 0.5% - 1%; A drainage channel is provided in the layered printed structure and the composite material protective layer; An embedded sensor network is distributed in key stress-bearing areas within the retaining wall to monitor stress, temperature and humidity data in real time.

[0006] Preferably, the fiber composite material is at least one of carbon fiber, glass fiber, and basalt fiber, and the addition ratio of the fiber composite material in the 3D printed concrete is 0.5%-1%, the length is 10-30mm, and the diameter is 0.1-0.5mm.

[0007] Preferably, the profile optimization path is generated by the following formula: ; in, is the local maximum stress, is the nominal stress.

[0008] Preferably, the sensor network includes fiber grating sensors, temperature sensors and humidity sensors, and the data sampling frequency is ≥10 Hz.

[0009] In addition, the present invention also discloses a construction method of a 3D printed concrete retaining wall based on an automatic feedback mechanism, which is characterized by comprising the following steps: Step S1: Generate an initial printing path according to the retaining wall design parameters, and implant a finite element model to calculate the initial stress distribution; Step S2: Start the 3D printer to print the first layer and collect real-time stress data simultaneously ; Step S3: Optimize subsequent printing parameters through dynamic adjustment algorithm, and adjust the extrusion rate Q according to the following formula: ; in, is the initial extrusion rate, is the rheological coefficient of the material, ranging from 0.2 to 0.5. and are the maximum stress and average stress of the current layer respectively; Step S4: Repeat steps S2-S3 until printing is completed, and perform post-processing and maintenance.

[0010] Furthermore, the finite element model in step S1 is divided into non-uniform grids, and the grid size decreases with the height gradient of the retaining wall.

[0011] Furthermore, in step S3, if , an alarm is triggered and printing is suspended, and epoxy resin is injected for local reinforcement. is the design stress.

[0012] Furthermore, the post-treatment curing includes covering with a curing film and spraying a nano-silicate penetrating crystallization agent, and the curing time is ≥ 7 days.

[0013] Furthermore, in step S2, a laser radar is used to scan the print layer morphology in real time, and path re-planning is triggered when the morphology deviation is greater than 3 mm.

[0014] Furthermore, the rheological coefficient of the material Dynamic correction according to ambient humidity H: ; in, The reference value is 0.3, and H is the real-time humidity.

[0015] The present invention has the following beneficial effects: 1. The present invention introduces a dynamic stress feedback mechanism: embedded sensors monitor stress in real time, and adjust the extrusion rate in combination with algorithms to prevent cracks, which greatly reduces the incidence of cracks during the construction process, saves materials, and reduces the cost of success. Moreover, after the construction is completed, the embedded sensors can continue to be connected to the later monitoring system for continuous maintenance monitoring; 2. The present invention optimizes the construction of special-shaped paths: based on finite element analysis, a printing path with a low stress concentration factor is generated, which is suitable for the construction of complex routes. The automated closed-loop control reduces manual intervention, greatly improving the construction efficiency. 3. The present invention introduces adaptive control according to the construction environment: a humidity correction coefficient is introduced to optimize the rheological behavior of the material, improve the stability of printing quality, and is suitable for complex geological and high humidity environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the retaining wall structure in the present invention; Figure 2 It is a flow chart of the dynamic stress feedback mechanism in the present invention; Figure 3 This is a flow chart of special-shaped path optimization in the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: See also Figures 1 to 3 , a 3D printed concrete retaining wall based on an automatic feedback mechanism, comprising: Layered printing structure 1, formed by stacking multiple layers of concrete materials layer by layer, with each layer being 8-15 mm thick; Retaining wall base 2, the retaining wall base is a C30 concrete base; Special-shaped optimization path, based on the printing trajectory generated by finite element stress analysis, maximizes the stress concentration factor inside the retaining wall ; Composite material protection 3, which is provided on the surface of the layered printed structure. The composite material protection layer contains evenly distributed fiber reinforcement materials. The addition ratio of fiber composite materials in 3D printed concrete is 0.5% - 1%; Drainage pipes 4 are arranged in the layered printing structure 1 and the composite material protection layer 3, and the number and position of the drainage pipes are specifically set according to the actual engineering environment; The embedded sensor network is distributed in the key stress-bearing areas of the retaining wall to monitor stress, temperature and humidity data in real time. Fiber Bragg grating sensors and temperature and humidity sensors can be arranged at the bottom, middle and top of the retaining wall respectively; the data sampling frequency is 10Hz and transmitted to the control center in real time; the real-time monitoring accuracy is improved and the construction failure rate is reduced.

[0018] Preferably, the fiber composite material is at least one of carbon fiber, glass fiber, and basalt fiber, and the addition ratio of the fiber composite material in the 3D printed concrete is 0.5%-1%, the length is 10-30mm, and the diameter is 0.1-0.5mm.

[0019] Preferably, the profile optimization path is generated by the following formula: ; in, is the local maximum stress, When the retaining wall is in an arc or stepped shape, the pouring path of the key stress-bearing area is optimized, and the thickness of the printing layer and the extrusion rate of the nozzle are dynamically adjusted according to the design size to ensure the strength of the heterogeneous structure and the coordination and consistency of the overall retaining wall construction.

[0020] Preferably, the sensor network includes fiber grating sensors, temperature sensors and humidity sensors, and the data sampling frequency is ≥10Hz. During the construction process, the number and type of sensors in the sensor network are arranged according to the key stress areas in the design. The embedded sensors monitor the stress in real time, and the extrusion rate is adjusted in time with the algorithm to prevent cracks, which greatly reduces the crack incidence rate during the construction process, saves materials, and reduces the cost of success. Moreover, after the construction is completed, the embedded sensors can continue to be connected to the later monitoring system for continuous maintenance and monitoring. In addition, the present invention also discloses a construction method of a 3D printed concrete retaining wall based on an automatic feedback mechanism, which is characterized by comprising the following steps: Step S1: Generate an initial printing path according to the retaining wall design parameters, and implant a finite element model to calculate the initial stress distribution; Step S2: Start the 3D printer to print the first layer and collect real-time stress data simultaneously ; Step S3: Optimize subsequent printing parameters through dynamic adjustment algorithm, and adjust the extrusion rate Q according to the following formula: ; in, is the initial extrusion rate, is the rheological coefficient of the material, ranging from 0.2 to 0.5. and are the maximum stress and average stress of the current layer, respectively; Step S4: Repeat steps S2-S3 until printing is completed, and perform post-processing and maintenance.

[0021] Furthermore, the finite element model in step S1 is divided into non-uniform grids, and the grid size decreases with the height gradient of the retaining wall.

[0022] Furthermore, in step S3, if , an alarm is triggered and printing is suspended, and epoxy resin is injected for local reinforcement. This design reduces the cracking rate, reduces the chance of rework, greatly saves material usage, and improves construction efficiency.

[0023] Furthermore, post-treatment maintenance includes covering the curing film and spraying the nano-silicate penetrating crystallization agent, and the curing time is ≥7 days. Cover the curing film within 1-6 hours after printing to prevent water evaporation; spray the nano-silicate penetrating crystallization agent after 3 days of curing to enhance the surface density; the total curing time is ≥7 days to ensure that the concrete strength meets the design requirements.

[0024] Furthermore, in step S2, a laser radar is used to scan the print layer morphology in real time, and path re-planning is triggered when the morphology deviation is greater than 3 mm.

[0025] Furthermore, the rheological coefficient of the material Dynamic correction according to ambient humidity H: ; in, The reference value is 0.3, and H is the real-time humidity. When the ambient temperature is lower than 10°C, increase the amount of concrete admixture to ensure the fluidity of the material.

[0026] The specific implementation methods of the above embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A 3D printed concrete retaining wall based on an automatic feedback mechanism, characterized in that: include: Layered printing structure, formed by stacking multiple layers of concrete materials layer by layer, with each layer being 8-15mm thick; A retaining wall base, wherein the retaining wall base is a C30 concrete base; Special-shaped optimization path, based on the printing trajectory generated by finite element stress analysis, maximizes the stress concentration factor inside the retaining wall ; A composite material protective layer is provided on the surface of the layered printed structure. The composite material protective layer contains evenly distributed fiber reinforcement materials. The addition ratio of fiber composite materials in 3D printed concrete is 0.5% - 1%; A drainage channel is provided in the layered printed structure and the composite material protective layer; An embedded sensor network is distributed in key stress-bearing areas within the retaining wall to monitor stress, temperature and humidity data in real time.

2. A 3D printed concrete retaining wall based on an automatic feedback mechanism according to claim 1, characterized in that: The fiber composite material is at least one of carbon fiber, glass fiber, and basalt fiber, and the addition ratio of the fiber composite material in the 3D printing concrete is 0.5%-1%, the length is 10-30mm, and the diameter is 0.1-0.5mm.

3. A 3D printed concrete retaining wall based on an automatic feedback mechanism according to claim 1, characterized in that: The profile optimization path is generated by the following formula: ； in, is the local maximum stress, is the nominal stress.

4. The 3D printed concrete retaining wall based on the automatic feedback mechanism according to claim 1, characterized in that: The sensor network includes a fiber grating sensor, a temperature sensor and a humidity sensor, and the data sampling frequency is ≥10 Hz.

5. A construction method of a 3D printed concrete retaining wall based on an automatic feedback mechanism according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step S1: Generate an initial printing path according to the retaining wall design parameters, and implant a finite element model to calculate the initial stress distribution; Step S2: Start the 3D printer to print the first layer and collect real-time stress data simultaneously ; Step S3: Optimize subsequent printing parameters through dynamic adjustment algorithm, and adjust the extrusion rate Q according to the following formula: ； in, is the initial extrusion rate, is the rheological coefficient of the material, ranging from 0.2 to 0.

5. and are the maximum stress and average stress of the current layer respectively; Step S4: Repeat steps S2-S3 until printing is completed, and perform post-processing and maintenance.

6. A construction method of a 3D printed concrete retaining wall based on an automatic feedback mechanism according to any one of claim 5, characterized in that: The finite element model in step S1 is divided by non-uniform meshes, and the mesh size decreases with the height gradient of the retaining wall.

7. A construction method of a 3D printed concrete retaining wall based on an automatic feedback mechanism according to any one of claim 5, characterized in that: In step S3, if , an alarm is triggered and printing is suspended, and epoxy resin is injected for local reinforcement. is the design stress.

8. A construction method of a 3D printed concrete retaining wall based on an automatic feedback mechanism according to any one of claim 5, characterized in that: Post-treatment maintenance includes covering with a maintenance film and spraying nano-silicate penetrating crystallization agent, and the maintenance time is ≥ 7 days.

9. A construction method of a 3D printed concrete retaining wall based on an automatic feedback mechanism according to any one of claim 5, characterized in that: In step S2, a laser radar is used to scan the print layer morphology in real time, and path re-planning is triggered when the morphology deviation is greater than 3 mm.

10. A construction method of a 3D printed concrete retaining wall based on an automatic feedback mechanism according to any one of claim 5, characterized in that: The material rheology coefficient Dynamic correction according to ambient humidity H: ； in, The reference value is 0.3, and H is the real-time humidity.

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