An assembled lining device and method with visualized internal force

Abstract

The present invention belongs to the technical field of tunnel engineering monitoring, and in particular relates to an assembled lining device and method for visualizing internal forces. The internal force visualization is based on thin film pressure sensing technology. The thin film pressure sensor is composed of a thin film polyester material, a piezoelectric material, a signal transmission silver wire and a signal connection component. The piezoelectric material layer is wrapped by two layers of polyester insulating surface, wherein two groups of strip-shaped piezoelectric materials are crisscrossed to form a complete grid, and each grid node is a pressure measuring unit. The sensor has a high fatigue life, strong deformation ability, fast response speed, and sensitive signal capture. It can realize real-time monitoring of the entire construction process and provide the possibility of visualizing the internal forces of the lining. The present invention effectively prevents construction and operation risks, reduces hidden dangers of tunnel lining diseases, and can be applied to tunnel projects under various complex geological conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel engineering monitoring, and in particular relates to an assembled lining device and method with visualized internal forces. Background Art

[0002] As infrastructure that traverses diverse terrains, tunnel engineering plays a vital role in modern transportation. Through underground excavation and tunnel construction, tunnels overcome natural obstacles, improving travel convenience and safety. Precast segments, commonly used as support structures in tunneling, are factory-cast and assembled into rings to form the tunnel lining, supporting and protecting the tunnel. They are particularly widely used in shield tunneling. Monitoring is essential to ensure the service quality and performance of precast segments. However, current monitoring practices still face several challenges that could impact the overall quality and safety of tunneling projects. Detection methods are limited, with traditional methods relying heavily on manual visual inspection and measuring tools, resulting in inefficiency and significant errors. Point sensors are installed on the segments to regularly measure changes in pressure, displacement, temperature, and other parameters to assess their long-term service stability. However, these approaches suffer from limited distribution of monitoring points, making it difficult to assess the overall condition of the segments. Furthermore, data collection is infrequent, requiring regular manual readings and preventing real-time monitoring.

[0003] Distributed fiber optic sensors have been widely researched and applied in tunnel engineering due to their high sensitivity, long-distance monitoring capabilities, and resistance to electromagnetic interference. These sensors utilize optical fibers as sensing elements to continuously and distributedly measure environmental parameters along the fiber path. Based on optical time-domain reflectometry (OTDR) technology, they detect physical changes along the fiber's length by measuring the scattering and reflection of light within the fiber. They are commonly used to monitor tunnel lining deformation, temperature distribution, dynamic response, and traffic flow, effectively eliminating safety hazards and ensuring safe tunnel operation. While distributed fiber optic sensors have demonstrated significant advantages in tunneling, they still face several drawbacks and challenges: 1. They are expensive, including testing, installation, ongoing maintenance, and calibration costs; 2. Installing distributed fiber optic sensors in complex or confined spaces is difficult; 3. Long-distance monitoring requires complex sensor wiring, and the data generated requires efficient processing and analysis methods; 4. The optical path and grating structure within fiber optic sensors are sensitive to temperature fluctuations, requiring real-time calibration and temperature compensation, which increases their complexity and cost.

[0004] As a new type of high-precision, high-sensitivity thin-film pressure sensor, when subjected to external pressure, the surface of the thin film undergoes slight deformation, resulting in a change in the film's resistance. By monitoring this resistance change, the applied pressure can be determined. Its cost-effectiveness and convenience make it a top choice for tunnel inspection, road construction, and health maintenance. By leveraging the sensor system's information-based data collection, it provides real-time output of the internal force trends of the monitored structure, achieving long-term, efficient visual monitoring and ensuring the safety and durability of civil engineering projects.

[0005] Therefore, the present invention is an assembled lining device and method with visualized internal forces, and provides a segment monitoring method based on a thin film pressure sensor, aiming to achieve full life cycle health monitoring of new prefabricated segments and provide a certain reference for the field of tunnel engineering. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an assembled lining device and method with visualized internal forces, thereby solving the problems raised in the above-mentioned background technology.

[0007] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0008] A method for visualizing internal forces in an assembled lining comprises the following steps:

[0009] S1. Assemble corresponding prefabricated segment molds according to different tunnel cross-sectional shapes. The prefabricated segment molds are made of mold steel and consist of a bottom plate, four side plates, and two upper covers, which can meet the requirements of tunnels with different diameters and cross-sectional shapes.

[0010] S2. Fabricate the steel skeleton according to the design specifications to ensure that the steel bars are properly connected to the mold; use brackets or fixtures to fix the steel skeleton in the mold to prevent displacement during the pouring process;

[0011] S3. Select a thin film pressure sensor with a suitable working range and temperature range, and cover it on the surface of the steel skeleton to monitor the pressure changes inside the prefabricated pipe segment in real time; wherein, the main structure of the thin film pressure sensor is a layer of semiconductor piezoelectric material wrapped in two layers of polyester insulating outer surface, with an overall thickness of only 0.2mm, a working range of 10000N, and a maximum working temperature of 100°C. The two groups of vertically intersecting strips of piezoelectric material in the piezoelectric material layer form a complete grid, and each grid node is a pressure measuring unit, and the size of each unit is 20mm×20mm. The horizontal and vertical layout dimensions can be customized according to the size and spacing of the steel bar, and the surface of the steel bar can be covered; in order to avoid the loose bonding between the polyester insulating outer surface under long-term monitoring conditions, the sensor is encapsulated, that is, epoxy resin is used as an adhesive; on the inner wall of the polyester material, a silver wire for transmitting signals is sprayed to connect the piezoelectric material layer to the signal connection component, and the signal connection component transmits, reads and processes the signal by connecting to the external circuit;

[0012] S4. Pour the concrete according to the designed mix ratio and vibrate it during the pouring process to remove any residual air.

[0013] S5. After pouring, steam curing is used to accelerate the hardening of the concrete, and the temperature and humidity are controlled to ensure steady development of the concrete strength. The steam curing uses the heat and humidity provided by steam to accelerate the cement hydration reaction in the concrete. The steam curing includes four stages: preheating stage, heating stage, constant temperature stage, and cooling stage.

[0014] S6. Remove the mold, perform demolding, trimming, and place in a water tank for curing. During this process, minimize damage to the segment surface. Use soft rubber pads to protect the segments if necessary. Demolding should proceed from top to bottom and from outside to inside to ensure a smooth and orderly demolding process.

[0015] An assembled lining device with visualized internal force includes: a prefabricated pipe segment and a steel frame; a thin film pressure sensor is provided on the steel frame; the thin film pressure sensor includes an upper surface of polyester material and a lower surface of polyester material; signal transmission silver wires and piezoelectric material layers are provided on the opposing surfaces of the upper surface of polyester material and the lower surface of polyester material; a signal connection component matching the signal transmission silver wire is provided at one end of the opposing surfaces of the upper surface of polyester material and the lower surface of polyester material; a pressure measuring unit is provided on the signal transmission silver wire and the piezoelectric material layer; and a pin is provided at one end of the thin film pressure sensor.

[0016] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art. Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described below at the same time:

[0017] 1. The thin film pressure sensor is a flexible sensor with strong adaptability to meet various working conditions.

[0018] 2. Thin film pressure sensors have the characteristics of high precision, fast response, small size, easy installation, and strong durability, which can realize efficient and accurate monitoring of the internal force of precast concrete segment structures.

[0019] 3. Thin film pressure sensors can more intuitively reflect the overall stress conditions of the structure, visualize internal data, and provide technical support for structural health monitoring.

[0020] 4. Compared to traditional sensors, the outer surface of the thin film pressure sensor is made of polymer material, which has excellent flexibility and plasticity. This feature can adapt to various irregular shapes and even curved surfaces, and can be widely used in various complex working conditions.

[0021] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described below are only some embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0023] In the picture:

[0024] Figure 1 This is a flow chart of the construction process of the present invention;

[0025] Figure 2 This is a disassembled perspective view of the thin film pressure sensor of the present invention;

[0026] Figure 3 This is a front view of the thin film pressure sensor package of the present invention;

[0027] Figure 4 This is a side view of the thin film pressure sensor package of the present invention;

[0028] Figure 5 This is the overall effect diagram of the prefabricated pipe segment of the present invention.

[0029] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0030] 1. Upper surface of polyester material; 2. Lower surface of polyester material; 3. Piezoelectric material layer; 4. Signal transmission silver wire; 5. Pressure measuring unit; 6. Signal connection component; 7. Prefabricated pipe segment; 8. Steel skeleton; 9. Thin film pressure sensor; 10. Pin.

[0031] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0032] The present invention will now be described in further detail with reference to the accompanying drawings.

[0033] Example 1: Please refer to Figure 1-5 As shown, in this embodiment, a method for visualizing internal forces of an assembled lining is provided, comprising the following steps:

[0034] S1. Assemble corresponding prefabricated segment molds according to different tunnel cross-sectional shapes. The prefabricated segment molds are made of mold steel and consist of a bottom plate, four side plates, and two upper covers, which can meet the requirements of tunnels with different diameters and cross-sectional shapes.

[0035] S2. Fabricate the steel skeleton according to the design specifications to ensure that the steel bars are properly connected to the mold; use brackets or fixtures to fix the steel skeleton in the mold to prevent displacement during the pouring process;

[0036] S3. Select a thin film pressure sensor with a suitable working range and temperature range, and cover it on the surface of the steel skeleton to monitor the pressure changes inside the prefabricated pipe segment in real time; wherein, the main structure of the thin film pressure sensor is a layer of semiconductor piezoelectric material wrapped in two layers of polyester insulating outer surface, with an overall thickness of only 0.2mm, a working range of 10000N, and a maximum working temperature of 100°C. The two groups of vertically intersecting strips of piezoelectric material in the piezoelectric material layer form a complete grid, and each grid node is a pressure measuring unit, and the size of each unit is 20mm×20mm. The horizontal and vertical layout dimensions can be customized according to the size and spacing of the steel bar, and the surface of the steel bar can be covered; in order to avoid the loose bonding between the polyester insulating outer surface under long-term monitoring conditions, the sensor is encapsulated, that is, epoxy resin is used as an adhesive; on the inner wall of the polyester material, a silver wire for transmitting signals is sprayed to connect the piezoelectric material layer to the signal connection component, and the signal connection component transmits, reads and processes the signal by connecting to the external circuit;

[0037] S4. Pour the concrete according to the designed mix ratio and vibrate it during the pouring process to remove any residual air.

[0038] S5. After pouring, steam curing is used to accelerate the hardening of the concrete, and the temperature and humidity are controlled to ensure steady development of the concrete strength. The steam curing uses the heat and humidity provided by steam to accelerate the cement hydration reaction in the concrete. The steam curing includes four stages: preheating stage, heating stage, constant temperature stage, and cooling stage.

[0039] S6. Remove the mold, perform demolding, trimming, and place in a water tank for curing. During this process, minimize damage to the segment surface. Use soft rubber pads to protect the segments if necessary. Demolding should proceed from top to bottom and from outside to inside to ensure a smooth and orderly demolding process.

[0040] Example 2: An assembled lining device with visualized internal force, comprising a prefabricated pipe segment 7 and a steel skeleton 8, a thin film pressure sensor 9 being arranged on the steel skeleton 8, the thin film pressure sensor 9 comprising a polyester material upper surface 1 and a polyester material lower surface 2, signal transmission silver wires 4 and piezoelectric material layers 3 being arranged on the opposing surfaces of the polyester material upper surface 1 and the polyester material lower surface 2, a signal connection component 6 cooperating with the signal transmission silver wire 4 being arranged at one end of the opposing surfaces of the polyester material upper surface 1 and the polyester material lower surface 2, a pressure measuring unit 5 being arranged on the signal transmission silver wire 4 and the piezoelectric material layer 3, and a pin 10 being arranged at one end of the thin film pressure sensor 9.

[0041] 1. The thin film pressure sensor is a flexible sensor with strong adaptability to meet various working conditions.

[0042] 2. Thin film pressure sensors have the characteristics of high precision, fast response, small size, easy installation, and strong durability, which can realize efficient and accurate monitoring of the internal force of precast concrete segment structures.

[0043] 3. Thin film pressure sensors can more intuitively reflect the overall stress conditions of the structure, visualize internal data, and provide technical support for structural health monitoring.

[0044] 4. Compared to traditional sensors, the outer surface of the thin film pressure sensor is made of polymer material, which has excellent flexibility and plasticity. This feature can adapt to various irregular shapes and even curved surfaces, and can be widely used in various complex working conditions.

[0045] Example 3: Figures 1 to 4 As shown, the present invention provides a method for visualizing internal forces in an assembled lining, comprising the following steps:

[0046] S1. Assemble the corresponding prefabricated segment mold according to the different cross-sectional shapes of the tunnel;

[0047] Refer to the tunnel cross-section shape and design dimensions to select the appropriate segment mold.

[0048] Rinse the mold before use to remove any surface impurities. Apply a release agent evenly to the inner surface to ensure a smooth surface and easy demolding. Strictly follow the assembly process to avoid mold deformation.

[0049] S2. Make the steel skeleton according to the design specifications and ensure the correct connection between the steel bars and the mold;

[0050] The steel bars are arranged in accordance with the specifications and connected by welding. Plastic brackets are used to fix the steel skeleton in the mold to prevent shifting during the pouring process.

[0051] Regularly inspect and debug equipment such as steel bar cutting machines and bending machines to ensure that steel bar processing meets the requirements of pipe segment production.

[0052] S3. Select a thin film pressure sensor with an appropriate operating range and temperature range and cover it on the surface of the steel skeleton to monitor the pressure changes inside the prefabricated segment in real time;

[0053] The selected thin film pressure sensor has a thickness of 0.2mm, an operating range of 10,000N, and an operating temperature of up to 100°C. Each load cell measures 20mm x 20mm. The horizontal and vertical layout dimensions can be customized according to the size and spacing of the rebar, and the surface of the rebar can be covered.

[0054] A further optimization scheme involves changing the geometry of the piezoresistive ink coating when pressure is applied. A change in pressure at any pressure measuring unit will cause a change in the resistance at that point, which in turn causes a change in the corresponding analog signal. This signal is then converted to digital after digital / analog conversion.

[0055] To further optimize the solution, in the I-Scan data analysis software, each pressure measuring unit will display the corresponding digital signal DO output value under pressure. After calibration, a functional relationship between DO value and pressure value can be established.

[0056] S4. Pour the concrete according to the designed mix ratio and vibrate it during the pouring process to remove any residual air.

[0057] During the pouring process, the uniformity and continuity of the concrete must be ensured to avoid quality defects of the segments caused by insufficient vibration or insufficient time.

[0058] Control the pouring speed and adopt layered pouring, with the thickness of each layer controlled at around 20cm to better expel bubbles and ensure the density of the concrete.

[0059] S5. After pouring, steam curing is used to accelerate the hardening of the concrete, and the temperature and humidity are controlled to ensure the steady development of the concrete strength;

[0060] By providing suitable temperature and humidity, the concrete hardening process can be significantly accelerated, the curing time can be shortened, and the early strength of concrete can be improved.

[0061] To further optimize the solution, maintaining the relative humidity above 90% can keep the concrete surface moist, thereby avoiding the occurrence of shrinkage cracks.

[0062] To further optimize the plan, the preheating stage: before pouring concrete, the temperature of the curing room is gradually increased to 30°C, which generally lasts for 1-2 hours; the heating stage: after pouring concrete, the temperature of the curing room is gradually increased to the predetermined curing temperature, which is generally 50°C to 80°C, and the heating time is generally 2-3 hours; the constant temperature stage: after reaching the predetermined curing temperature of 50°C to 80°C, the constant temperature state is maintained for 6-12 hours to accelerate the hardening of the concrete under constant temperature and humidity conditions; the cooling stage: stop inputting steam into the curing room, and gradually reduce the temperature to room temperature. The cooling time generally lasts for 2-3 hours.

[0063] S6. Remove the mold for demoulding, trimming, and place in a water pool for curing;

[0064] When demolding the pipe segment, use a thermometer to measure the temperature inside the bolt hole of the pipe segment. If the temperature difference does not exceed 20℃, demolding can be carried out.

[0065] To further optimize the solution, loosen the bolts securing the grouting holes, sequentially open the mold side formwork and mold end plates, and remove the segments from the mold by attaching the lifting device. The segments are hoisted onto a segment flipper and flipped 90°. A dedicated lifting device is then used to lift the sideways segments onto a flatbed truck. During the demolding process, hammering or striking the segments, which could damage them, is strictly prohibited.

[0066] Further optimization plans should be implemented to minimize damage to the segment surface during demoulding and demolding. Soft rubber pads should be used to protect the segments when necessary. Demolding should proceed from top to bottom and from outside to inside to ensure a smooth and orderly demolding process.

[0067] To further optimize the plan, after the pipe segments are demoulded, the outer surface of the pipe segments is trimmed. When repairing, a foam sponge is used to dip in cement mortar and then smoothed with a putty spoon.

[0068] To further optimize the solution, fill the curing tank with tap water and add water frequently to maintain a constant water level to submerge the specimens. The curing time is generally 3-7 days, with the temperature controlled at 20°C ± 1°C.

[0069] S7. Complete the inspection of finished products to ensure they meet factory quality standards;

[0070] Check whether the surface of the pipe segment has defects such as cracks and bubbles. The surface should be kept flat and smooth without obvious defects. Check whether the length, width, height, wall thickness and other dimensions of the pipe segment meet the design requirements. The dimensional deviation should be within the allowable range. X-ray detection should be used to check whether the steel bar configuration inside the pipe segment meets the design requirements. Check whether the compressive strength, bending strength, etc. of the pipe segment meet the specification requirements.

[0071] After the inspection, prepare the inspection report, summarize all the results, and mark the unqualified segments

[0072] S8. Transfer the qualified segments to the storage area, record their numbers, and wait for transportation to the construction site.

[0073] Label qualified segments and number them, indicating production date, inspection results, etc. Use a forklift to smoothly transfer the segments to the storage area to avoid collision and damage.

[0074] Further optimize the plan to keep the storage area comfortable, dry, and well ventilated, and reduce humidity and sunlight exposure.

[0075] To further optimize the plan, plastic film was laid on the floor of the storage area to prevent moisture penetration.

[0076] The present invention is not limited to the above-described embodiments. Any structural changes made under the guidance of the present invention, which have the same or similar technical solutions as the present invention, should be understood to fall within the scope of protection of the present invention. The technologies, shapes, and structural parts not described in detail in the present invention are all well-known technologies.

Claims

1. A method for visualizing internal forces in an assembled lining, characterized in that: The following steps are involved: S1. Assemble the corresponding prefabricated segment mold according to the different cross-sectional shapes of the tunnel; S2. Make the steel skeleton according to the design specifications and ensure the correct connection between the steel bars and the mold; S3. Select a thin film pressure sensor with an appropriate working range and temperature range, and cover it on the surface of the steel skeleton to monitor the pressure change inside the prefabricated pipe segment in real time, wherein the thin film pressure sensor (9) is arranged on the steel skeleton (8), and the thin film pressure sensor (9) includes a polyester material upper surface (1) and a polyester material lower surface (2), and a signal transmission silver wire (4) and a piezoelectric material layer (3) are arranged on the opposite surfaces of the polyester material upper surface (1) and the polyester material lower surface (2), and a signal connection component (6) matched with the signal transmission silver wire (4) is arranged at one end of the opposite surface of the polyester material upper surface (1) and the polyester material lower surface (2), and a pressure measuring unit (5) is arranged on the signal transmission silver wire (4) and the piezoelectric material layer (3), and a pin (10) is arranged at one end of the thin film pressure sensor (9); S4. Pour the concrete according to the designed mix ratio and vibrate it during the pouring process to remove any residual air. S5. After pouring, steam curing is used to accelerate the hardening of the concrete, and the temperature and humidity are controlled to ensure the steady development of the concrete strength; S6. Remove the mold for demoulding, trimming, and place in a water pool for curing; S7. Complete the inspection of finished products to ensure they meet factory quality standards; S8. Transfer qualified segments to the storage area, record their numbers, and wait for transportation to the construction site; In the S3, the main structure of the thin film pressure sensor is a layer of semiconductor piezoelectric material wrapped in two layers of polyester insulating outer surface. The overall thickness is only 0.2mm, the working range is 10000N, and the operating temperature can reach up to 100℃. In S3, signal transmission silver wires are sprayed on the inner wall of the polyester material to connect the piezoelectric material layer to the signal connection component, and the signal connection component transmits, reads and processes signals by connecting to an external circuit.

2. The method for visualizing internal forces of prefabricated lining according to claim 1, characterized in that: In S1, the prefabricated segment mold is made of mold steel and consists of a base plate, four side plates and two upper covers, which can meet the needs of tunnels with different diameters and cross-sectional shapes.

3. The method for visualizing internal forces of prefabricated lining according to claim 1, characterized in that: In S2, brackets or fixtures are used to secure the steel skeleton in the mold to prevent displacement during pouring.

4. The method for visualizing internal forces of prefabricated lining according to claim 1, characterized in that: In S3, two groups of vertically intersecting strips of piezoelectric materials in the piezoelectric material layer form a complete grid. Each grid node is a pressure measuring unit. The size of each unit is 20mm×20mm. The horizontal and vertical layout dimensions can be customized according to the size and spacing of the steel bars, and the surface of the steel bars can be covered.

5. The method for visualizing internal forces of prefabricated lining according to claim 1, characterized in that: In S3, in order to avoid loose bonding between the outer surfaces of the polyester insulation under long-term monitoring conditions, the sensor is encapsulated using epoxy resin as an adhesive.

6. The method for visualizing internal forces of prefabricated lining according to claim 1, characterized in that: In S5, steam curing uses the heat and humidity provided by steam to accelerate the cement hydration reaction in concrete, which includes four stages: preheating stage, heating stage, constant temperature stage and cooling stage.

7. The method for visualizing internal forces of prefabricated lining according to claim 1, characterized in that: In S6, using soft rubber pads to protect the segments can reduce damage to the segment surface during demolding and demolding. Demolding should be done from top to bottom and from outside to inside to ensure a smooth and orderly demolding process.

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