Bimodal flexible sensor and geotechnical deformation and settlement monitoring method

Abstract

The application discloses a bimodal flexible sensor and a rock-soil mass deformation and settlement method, and relates to the technical field of rock-soil engineering deformation monitoring. The bimodal flexible sensor comprises a flexible substrate, one side of the flexible substrate is provided with a first flexible sensing layer, and the other side of the flexible substrate is provided with a second flexible sensing layer; a plurality of electrodes are arranged at equal intervals on the first flexible sensing layer and the second flexible sensing layer; the flexible substrate, the first flexible sensing layer, the second flexible sensing layer and the electrodes are wrapped by an encapsulation layer; the first flexible sensing layer and the second flexible sensing layer have a resistance difference in the process of monitoring soil deformation, and the soil deformation amount is obtained based on the resistance difference. The application realizes rock-soil mass deformation and settlement based on the resistance difference of the flexible sensing layer in the bimodal flexible sensor, can identify the soil deformation type, and improves the monitoring precision.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering deformation monitoring technology, and in particular to a dual-modal flexible sensor and a method for monitoring the deformation and settlement of soil and rock masses, applicable to the monitoring of deformation and settlement of above-ground and underground engineering projects such as roadbed and ground settlement and tunnel deformation. Technical Background

[0002] Currently, methods for monitoring soil internal deformation mainly include layered settlement gauges, resistance strain gauges, and inclinometers. While these technologies can monitor soil internal settlement and deformation, they are generally point-based and cannot perform large-scale or continuous monitoring. Fiber optic monitoring technology, due to its advantages such as high precision, long sensing distance, and immunity to electromagnetic interference, has been widely used in distributed soil deformation monitoring. However, distributed fiber optics installed horizontally can only monitor tensile deformation of the soil along the fiber axis and cannot effectively identify the deformation modes and amounts in the vertical direction (such as settlement and collapse). Furthermore, as a brittle material, fiber optics typically have a small distributed strain measurement range (generally not exceeding 2%), making it difficult to effectively capture the maximum strain (up to 15%) throughout the entire process of roadbed disasters. In addition, the high cost of distributed fiber optic demodulation instruments and sensors limits their application in large-scale engineering projects.

[0003] In recent years, the rapid development of flexible conductive materials has driven the widespread application of flexible bending sensors in fields such as human health monitoring and biomimetic robots. The core working principle of these sensors lies in the fact that bending deformation significantly alters the electrical signal characteristics of the internal conductive material, and the bending curvature and the change in electrical signal are usually linearly correlated. In geological disasters such as soil settlement and collapse, soil deformation exhibits significant spatial non-uniformity. Flexible bending sensors, with their excellent flexibility and deformability, can form a tight coupling with the soil, monitoring the amount of soil settlement by measuring the local curvature changes induced by soil settlement. However, soil settlement deformation is a complex process involving both vertical compression and horizontal deformation. Existing flexible bending sensors struggle to achieve simultaneous and comprehensive monitoring of both vertical and horizontal deformation of soil and rock. Furthermore, soil and rock deformation often exhibits strong directionality, but most existing sensors lack effective direction identification capabilities, failing to accurately identify the specific location of the deformation. Simultaneously, the soil and rock deformation monitoring process is often accompanied by changes in the ambient temperature field, and existing sensors generally lack effective temperature compensation mechanisms, resulting in significant temperature interference with the monitoring data, affecting measurement accuracy and reliability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a dual-modal flexible sensor and a method for detecting soil and rock deformation and settlement. This method utilizes the resistance difference of the flexible sensing layer in the dual-modal flexible sensor to detect soil and rock deformation and settlement, and can identify soil deformation types, thereby improving monitoring accuracy.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In a first aspect, embodiments of the present invention provide a dual-modal flexible sensor, comprising a flexible substrate, a first flexible sensing layer on one side of the flexible substrate, and a second flexible sensing layer on the other side; a plurality of electrodes are arranged at equal intervals between the first flexible sensing layer and the second flexible sensing layer; the flexible substrate, the first flexible sensing layer, the second flexible sensing layer, and the electrodes are encapsulated within an encapsulation layer; a resistance difference exists between the first flexible sensing layer and the second flexible sensing layer during the monitoring of soil deformation, and the amount of soil deformation is obtained based on the resistance difference.

[0007] As a further implementation, an encapsulation layer is also included, wherein the electrode connecting wire extends from the encapsulation layer by a predetermined length.

[0008] As a further implementation, the thickness of the flexible substrate is 1.5~2.5mm, the thickness of the first flexible sensing layer and the second flexible sensing layer is 0.3~0.8mm, the electrode thickness is 0.3~0.5mm, and the encapsulation layer thickness is 1.5~2.0mm.

[0009] As a further implementation, the materials of the first flexible sensing layer and the second flexible sensing layer are a mixture of carbon nanotubes, carbon black, polydimethylsiloxane and n-hexane, the flexible substrate is polydimethylsiloxane or hydrogenated styrene-butadiene block copolymer, and the encapsulation layer is one of polydimethylsiloxane, polyurethane or hydrogenated styrene-butadiene block copolymer.

[0010] As a further implementation, the first flexible sensing layer and the second flexible sensing layer are applied to the surface of a flexible substrate using a scraping method and then heated and cured under a set temperature condition.

[0011] Among them, the blade coating method is only one way to place the sensing layer on the surface of the flexible substrate. Other methods include bar coating, roller coating, 3D printing, and screen printing.

[0012] As a further implementation, the encapsulation layer is formed using a template method. After encapsulation material is poured onto the flexible substrate, the first flexible sensing layer, the second flexible sensing layer, and the outer side of the electrode, the encapsulation layer is placed horizontally in a drying oven at a set temperature to dry.

[0013] Secondly, embodiments of the present invention also provide a method for soil and rock deformation and settlement based on the aforementioned dual-modal flexible sensor, comprising:

[0014] The dual-modal flexible sensor is laid flat inside the soil and connected to an external resistance acquisition instrument and transmission system.

[0015] Obtain the initial resistance, thickness, spacing, and sensing of the first and second flexible sensing layers, and calculate the average curvature between any two electrodes.

[0016] The deformation difference between any two electrodes is calculated based on the average curvature and the total length of the flexible sensing layer after deformation.

[0017] The soil deformation type is determined based on the resistance difference between the first and second flexible sensing layers. The maximum deformation of the soil measured by the dual-mode flexible sensor is obtained by superimposing the deformation difference values. The deformation of the soil relative to its initial state is calculated by combining the deformation observation piles and deformation benchmarks embedded in the soil.

[0018] As a further implementation, the resistance difference between the first flexible sensing layer and the second flexible sensing layer is used to eliminate the vertical soil monitoring error caused by horizontal soil deformation:

[0019] ;

[0020] in, This indicates the change in resistance of the first flexible sensing layer. This indicates the change in resistance of the first flexible sensing layer. This represents the change in resistance caused by the vertical deformation of the first flexible sensing layer. This indicates the change in resistance caused by the vertical deformation of the second flexible sensing layer.

[0021] As a further implementation, the average curvature between any two electrodes Represented as:

[0022]

[0023] Where D represents the spacing between the first flexible sensing layer and the second flexible sensing layer. R0 represents the thickness of the flexible sensing layer, R0 represents the initial resistance of the first and second flexible sensing layers, and GF represents the sensitivity of the flexible sensing layer.

[0024] As a further implementation method, hour, For soil settlement; hour, The soil mass is raised;

[0025] The formula for calculating the maximum deformation of soil is:

[0026] ;

[0027] The difference in deformation between any two electrodes is expressed as: :

[0028]

[0029] in, and These represent the electrode designations. for and The initial length between, Use absolute values ​​for calculation.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) The dual-modal flexible sensor of the present invention has flexible sensing layers on both sides of the flexible substrate, which can identify the bending direction and be used to determine the type of soil deformation. By monitoring the resistance difference of the flexible sensing layer caused by soil deformation through the dual-modal flexible sensor, the average curvature of the dual-modal flexible sensor is obtained, and the amount of soil deformation is calculated from it, so as to achieve accurate monitoring of soil deformation.

[0032] (2) This invention uses the resistance difference as a monitoring index to detect the deformation and settlement of soil and rock, which can effectively reduce the resistance error caused by tensile strain and improve the monitoring accuracy. Furthermore, the positive or negative value of the resistance difference of the flexible sensing layer is used to determine whether the soil is settling or heaving, thereby realizing the identification of the direction of soil deformation. Therefore, through the curvature distributed measurement theory, it can adapt to complex soil deformation environments and achieve high-precision monitoring of different deformation modes in the same dual-mode flexible sensor. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, 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 improper limitation of the invention.

[0034] Figure 1 This is a longitudinal cross-sectional view of the dual-modal flexible sensor according to one or more embodiments of the present invention;

[0035] Figure 2 This is a top view of a dual-modal flexible sensor according to one or more embodiments of the present invention;

[0036] Figure 3 This is a flowchart illustrating the fabrication process of a dual-modal flexible sensor according to one or more embodiments of the present invention.

[0037] Figure 4 This invention relates to the layout diagram and monitoring principle of a dual-modal flexible sensor for roadbed deformation monitoring according to one or more embodiments;

[0038] Figure 5This is a layout diagram of the dual-modal flexible sensor for monitoring settlement of overburden in tunnels according to one or more embodiments of the present invention.

[0039] Figure 6 This is a graph showing the rate of change of resistance as a function of temperature according to one or more embodiments of the present invention.

[0040] Among them, 1-first flexible sensing layer, 2-encapsulation layer, 3-flexible substrate, 4-second flexible sensing layer, 5-electrode, 6-wire, 7-resistance acquisition instrument and transmission system, 8-dual-modal flexible sensor, 9-roadbed, 10-deformation benchmark point, 11-deformation observation pile, 12-road surface, 13-tunnel. Detailed Implementation

[0041] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0042] Example 1:

[0043] This embodiment provides a dual-modal flexible sensor, such as... Figure 1 and Figure 2 As shown, the system includes a flexible substrate 3, with flexible sensing layers on both sides. For ease of description, one side of the flexible sensing layer is designated as the first flexible sensing layer 1, and the other side as the second flexible sensing layer 4, forming a sandwich structure. By setting two flexible sensing layers, the resulting dual-modal flexible sensor can monitor different deformation modes of the soil in the vertical direction (such as settlement and collapse) and the horizontal direction (such as cracking), and can identify the deformation direction. Using the resistance difference between the two flexible sensing layers as a monitoring index for settlement monitoring can effectively reduce resistance errors caused by tensile strain and improve monitoring accuracy.

[0044] Two flexible sensing layers are fixed to the surface of the flexible substrate 3 by a scraping method. During the scraping process, one side of the flexible substrate 3 needs to be scraped first, and after heating and curing, the other side of the flexible substrate 3 needs to be scraped to form a stable flexible sensing layer on both sides of the flexible substrate 3.

[0045] It should be noted that the blade coating method is only one way to place the sensing layer on the surface of a flexible substrate. Other methods include bar coating, roller coating, 3D printing, and screen printing.

[0046] Multiple electrodes 5 are evenly spaced on the flexible sensing layer. For example, one electrode 5 is placed at each end of the flexible sensing layer, and another electrode 5 is placed between the two end electrodes 5. The electrodes 5 are attached to the flexible sensing layer with conductive silver paste, and the electrodes 5 are connected to wires 6. The flexible sensing layer, flexible substrate 3, electrodes 5, and wires 6 are all wrapped by an encapsulation layer 2, and the wires 6 have external connectors extending out of the encapsulation layer 2. The encapsulation is performed using a template method. After assembling the flexible sensing layer, flexible substrate 3, electrodes 5, conductive silver paste, and wires 6, they are placed in a template, encapsulation material is poured, and the template is placed horizontally in a drying oven at a certain temperature for a certain period of time to dry, ultimately forming the finished structure.

[0047] In this embodiment, electrode 5 is a copper electrode.

[0048] To effectively monitor soil and rock deformation and settlement, this embodiment uses a flexible base 3 with a thickness of 1.5–2.5 mm, a flexible sensing layer with a thickness of 0.3–0.8 mm, an electrode 5 with a thickness of 0.3–0.5 mm, and an encapsulation layer 2 with a thickness of 1.5–2.0 mm. The dimensions selected in this embodiment ensure good sensor sensitivity and monitoring accuracy, while also reducing interference from the flexible sensor's placement within the soil, thus more accurately reflecting the amount of soil deformation and ensuring the authenticity of the monitoring data.

[0049] Regarding the selection of materials, the first flexible sensing layer 1 and the second flexible sensing layer 4 are made of a mixture of carbon nanotubes, carbon black, polydimethylsiloxane and n-hexane. The flexible substrate 3 is made of polydimethylsiloxane or hydrogenated styrene-butadiene block copolymer. The encapsulation layer 2 is made of one of polydimethylsiloxane, polyurethane or hydrogenated styrene-butadiene block copolymer.

[0050] like Figure 3 As shown, the fabrication process of the dual-modal flexible sensor in this embodiment is as follows:

[0051] Step 1: Weigh carbon nanotubes and carbon black, pour them into a beaker, and stir with a glass rod for 5-10 minutes until the carbon nanotubes and carbon black are fully mixed to obtain a carbon nanotube and carbon black mixture. Then, add n-hexane solution to the mixture, adjust the magnetic stirrer speed to 800-1200 rpm, and stir for 15-20 minutes at an ambient temperature of 25-35℃ to obtain mixture A.

[0052] Step 2: Add polydimethylsiloxane to the well-stirred mixture A, and homogenize it using a high-shear homogenizer for 30-45 min to obtain a multidimensional hybrid conductive filler.

[0053] In this embodiment, the amount of carbon nanotube and carbon black composite conductive material is 1.5% to 2.5% of the mass of polydimethylsiloxane, wherein the mass ratio of carbon nanotube and carbon black to the total mass of composite conductive filler is 65% to 75% and 25% to 35%, respectively, and the amount of n-hexane accounts for 50% to 80% of the mass of polydimethylsiloxane.

[0054] Step 3: Cut the flexible substrate 3 to the required size and wipe the surface of the substrate with alcohol to ensure it is clean. Place the cut flexible substrate 3 on the coating machine, ensuring the surface is flat. Adjust the coating speed of the coating machine to 25~35 mm / s, and control the coating thickness between 0.3~0.8 mm. Pour the homogenized multidimensional hybrid conductive filler into the blade of the coating machine, start the coating machine, and complete the coating to obtain strip A.

[0055] Step 4: Place the coated strip A into a vacuum drying oven, start the vacuum pump, and adjust the air pressure inside the drying oven to -0.08~-0.1 MPa. Turn off the vacuum pump and evacuate for 30~40 minutes. When there are no air bubbles on the surface of strip A, open the air inlet valve to make the internal and external atmospheric pressure equal. Set the drying oven temperature to 70~85℃ and continue drying for 1~1.5 hours to complete the drying process.

[0056] Step 5: Place the dried strip A with the uncoated side facing up on the coating machine, and repeat the coating and drying process in steps 3 and 4 to obtain two layers of strip B.

[0057] Step 6: Coat the surfaces of the first flexible sensing layer 1 and the second flexible sensing layer 4 with conductive silver paste. The width of the conductive silver paste is 1~2 mm. Attach an electrode 5 of the same width to the conductive silver paste. An external wire 6 is sandwiched between the electrode 5 and the conductive silver paste.

[0058] Step 7: Place the assembled strip in the template, pour polydimethylsiloxane, and dry it horizontally in a drying oven at 70~85 ℃ for 1.5~2 h.

[0059] Step 8: Remove the dried strip and demold it to obtain a dual-modal flexible sensor that can be used for soil and rock deformation and settlement.

[0060] The dual-modal flexible sensor in this embodiment has the function of distributed deformation monitoring of soil in both vertical and horizontal directions. It can realize distributed monitoring and improve the overall monitoring accuracy through data mutual correction, thereby reducing the maintenance cost for long-term use.

[0061] Example 2:

[0062] This embodiment is a material replacement embodiment for the first flexible sensing layer 1 and the second flexible sensing layer 4 of the dual-modal flexible sensor. The preparation process is as follows:

[0063] Step 1: Mix silver nanoparticles (Ag NPs) (particle size 50±10 nm) and silver nanowires (Ag NWs) (diameter 80 nm, length 20-50 μm) at a mass ratio of 3:1.

[0064] Step 2: Add 0.5 wt% polyvinylpyrrolidone (PVP) as a dispersant and sonicate in ethanol solution (40 kHz, 300 W) for 30 min.

[0065] Step 3: Centrifuge and wash (8000 rpm, 10 min) to remove uncoated PVP, and vacuum dry at 60 ℃ for later use.

[0066] Step 4: Dissolve hydrogenated styrene-butadiene block copolymer (SEBS) in toluene to prepare a 15 wt% solution, and stir magnetically at 60 °C for 6 h until completely transparent.

[0067] Step 5: Add Ag NWs (70% of the total filler) to the SEBS solution, and use a stirrer to shear at 2000 rpm for 15 minutes while simultaneously applying pulsed ultrasound (2 seconds on, 1 second off, 500 W power) to break down the nanowire aggregates.

[0068] Step 6: Slowly add Ag NPs (30%), reduce the speed to 800 rpm, continue stirring for 30 min, add 0.1wt% KH-550 silane coupling agent, react at 70 ℃ for 2 h to improve interfacial bonding, and obtain a mixed slurry.

[0069] Step 7: Cut the flexible substrate to the required size, adjust the coating speed of the squeegee to 25~35 mm / s, and control the coating thickness between 0.3~0.6 mm. Use the squeegee to apply the mixed slurry onto the flexible substrate to obtain strip A.

[0070] Step 8: Place the coated strip A into a vacuum drying oven, start the vacuum pump and adjust the air pressure inside the drying oven to -0.08~-0.1 MPa, evacuate for 30~40 minutes, and when there are no bubbles on the surface of strip A, open the air inlet valve to make the internal and external atmospheric pressure equal. Turn on the drying oven, adjust the temperature to 50 ℃~65 ℃, dry for 4~5 hours, and then move it to an environment of 25~30 ℃ to complete the drying process.

[0071] Step 9: Repeat steps 7 and 8 to obtain the upper and lower stripes B;

[0072] Step 10: Coat the surfaces of the first flexible sensing layer 1 and the second flexible sensing layer 4 with conductive silver paste. The width of the conductive silver paste is 1~2 mm. Attach electrodes of the same width to the conductive silver paste and sandwich external wires between the electrodes and the conductive silver paste.

[0073] Step 11: Place the assembled strip in the template, pour polydimethylsiloxane, and dry it horizontally in a drying oven at 70~85 ℃ for 1.5~2 h.

[0074] Step 12: Remove the dried strip and demold it to obtain a dual-modal flexible sensor that can be used for soil and rock deformation and settlement.

[0075] The materials of the first flexible sensing layer and the second flexible sensing layer mentioned in Examples 1 and 2 can also be prepared using other carbon-based conductive materials, metal-based materials or piezoelectric materials.

[0076] Example 3:

[0077] This embodiment provides a method for soil and rock deformation and settlement based on the dual-modal flexible sensor described in Embodiment 1, including:

[0078] Step 1: Lay the dual-modal flexible sensor flat inside the soil and connect it to an external resistance acquisition instrument and transmission system 7 to collect changes in resistance signals.

[0079] Step 2: Obtain the resistance difference between the first flexible sensing layer 1 and the second flexible sensing layer 4 during soil deformation, and based on the initial resistance of the flexible sensing layers... , thickness of flexible sensing layer The spacing between the first flexible sensing layer 1 and the second flexible sensing layer 4 The average curvature between any two electrodes is obtained through sensing calculations.

[0080] Step 3: Obtain the deformation difference between the two electrodes 5 using the average curvature and the total length of the sensing layer after deformation.

[0081] Step 4: Based on the sign of the average curvature of the dual-modal flexible sensor, determine whether the soil is settling or heaving, and then superimpose the deformation to calculate the final deformation of the soil.

[0082] In this embodiment, the dual-modal sensor acquires three sets of key data when detecting soil:

[0083] Resistance change of the first flexible sensing layer 1 The resistance change of the second flexible sensing layer 4 The resistance difference between the first flexible sensing layer 1 and the second flexible sensing layer 4 .

[0084] By monitoring the above three sets of resistance data, the deformation of the soil can be effectively reflected; at the same time, the three sets of data can be cross-corrected, thereby improving the accuracy of the monitoring results and the precision of the calculation. Furthermore, the resistance difference between the first flexible sensing layer 1 and the second flexible sensing layer 4 can be utilized... When monitoring the deformation and settlement of soil and rock masses, it can eliminate the vertical monitoring error caused by horizontal deformation of the soil.

[0085] Furthermore, the principle for eliminating monitoring errors is as follows:

[0086] (1)

[0087] (2)

[0088] Since the first flexible sensing layer 1 and the second flexible sensing layer 4 are arranged in layers, their deformation in the horizontal direction is the same, that is... Furthermore, the sensitivity of the flexible sensing layer and initial resistance Same, by It can be seen that the change in resistance is caused by deformation in the horizontal direction. Therefore, we can further obtain:

[0089] (3)

[0090] Furthermore, the average curvature between any two electrodes 5 Represented as:

[0091] (4)

[0092] Furthermore, the difference in deformation between any two electrodes 5 is expressed as: :

[0093] (5)

[0094] in, and These represent the designations for electrode 5. for and The initial length between, Use absolute values ​​for calculation.

[0095] The final length L of the dual-modal sensor after deformation is:

[0096] (6)

[0097] The sign of the average curvature is determined based on the magnitude of the resistance change of the first flexible sensing layer 1. If this is due to the dual-mode sensor... The deformation of the first flexible sensing layer is greater than that of the second flexible sensing layer, that is... ,therefore This indicates soil settlement; similarly, if The deformation of the first flexible sensing layer is smaller than that of the second flexible sensing layer, that is... ,therefore , indicating that the soil has bulged up.

[0098] The formula for calculating the maximum deformation of soil is:

[0099] (7)

[0100] Among them, the following conditions must be met:

[0101] (1) If and Stop summing when the time comes;

[0102] (2) Otherwise, continue to accumulate.

[0103] This embodiment uses a dual-modal flexible sensor to monitor the resistance difference of the flexible sensing layer caused by soil deformation, obtains the average curvature of the dual-modal flexible sensor, and calculates the amount of soil deformation, thus achieving accurate monitoring of soil deformation. Using the resistance difference as a monitoring index for soil and rock deformation and settlement can effectively reduce resistance errors caused by tensile strain and improve monitoring accuracy. Furthermore, the sign of the resistance difference of the flexible sensing layer indicates whether the soil is settling or heaving, thereby identifying the direction of soil deformation. Therefore, this embodiment, through the curvature distributed measurement theory, can adapt to complex soil deformation environments and achieve high-precision monitoring of different deformation modes within the same dual-modal flexible sensor.

[0104] The dual-modal flexible sensor 8 in this embodiment is provided with two flexible sensing layers. Through dual-layer signal differential, temperature interference can be canceled, so that the difference signal is almost unaffected by temperature changes, achieving efficient temperature compensation and ensuring the reliable application of the flexible sensor in complex temperature environments.

[0105] The relationship between the resistance change rate and the difference in resistance change rate between the first flexible sensing layer 1 and the second flexible sensing layer 4 as a function of temperature was calibrated through indoor tests. Figure 6 As can be seen, the resistance change rate (ΔR / R0) of the two flexible sensing layers generally decreases with increasing temperature, while the difference between them is almost a horizontal straight line. This indicates that the difference in resistance change rate between the two flexible sensing layers (ΔR1 / R0 - ΔR2 / R0) hardly changes with temperature, meaning the difference signal is largely unaffected by temperature, proving the effectiveness of the temperature compensation strategy. In practical applications, the influence of temperature is suppressed, improving measurement accuracy and stability.

[0106] Example 4:

[0107] This embodiment provides a method for monitoring soil and rock deformation and settlement based on the dual-modal flexible sensor described in Embodiment 1. This embodiment mainly focuses on the simultaneous monitoring of differential settlement and horizontal deformation of the roadbed. Figure 4 As shown, it includes the following steps:

[0108] According to the requirements of the "Technical Specifications for Highway Subgrade Construction", an observation section should be set up every 100-200m along the route. The number of sections should be adjusted according to the actual soil conditions and length of the construction site. In transition sections and areas with significant changes in geological conditions, the number of monitoring sections should be increased appropriately. In transition sections, one to two monitoring sections should be ensured. Deformation observation piles 11 should be buried at the centerline of the route on the ground at the bottom of the subgrade, and the initial position should be recorded by taking the deformation reference point 10 at the top of the pile.

[0109] During the roadbed filling construction, a dual-modal flexible sensor 8 is embedded inside the roadbed 9. The wire 6 led out from the dual-modal flexible sensor 8 is connected to the resistance acquisition instrument and transmission system 7. The resistance acquisition instrument and transmission system 7 collect the changes in resistance signal. Combined with the settlement deformation calculation formula in Example 3, the roadbed deformation is obtained. The deformation observation pile 11 and the top deformation benchmark point 10 are used as the benchmark and reference for the first observation. The roadbed deformation obtained by the dual-modal flexible sensor is compared to obtain the roadbed soil deformation.

[0110] Example 5:

[0111] This invention provides a method for monitoring soil and rock deformation and settlement based on the dual-modal flexible sensor described in Embodiment 1. This embodiment mainly focuses on the simultaneous monitoring of settlement and horizontal deformation of the upper soil and internal soil of the tunnel. Figure 5 As shown, it includes the following steps:

[0112] During the backfilling process after the tunnel construction is completed, dual-mode flexible sensors 8 are deployed in two layers. The first layer is laid directly on the upper surface of the lining, and the monitoring interface is voided. The second layer is arranged in the fine-grained material covering layer below the backfilled surface. Waterproof wires are used to connect each sensing unit, and the cables extend longitudinally along the tunnel to the tunnel equipment chamber.

[0113] The resistance signal changes are acquired through a resistance acquisition instrument and transmission system 7. The resistance difference of the flexible sensing layer caused by soil deformation is monitored by a dual-modal flexible sensor 8. The average curvature of the dual-modal flexible sensor 8 is obtained, and the soil deformation is calculated from this, achieving accurate monitoring of soil deformation. The specific calculation method is the same as in Example 3, and will not be repeated here.

[0114] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A dual-modal flexible sensor, characterized in that, The device includes a flexible substrate, a first flexible sensing layer on one side of the flexible substrate, and a second flexible sensing layer on the other side; multiple electrodes are arranged at equal intervals in the first and second flexible sensing layers; the flexible substrate, the first flexible sensing layer, the second flexible sensing layer, and the electrodes are encapsulated within an encapsulation layer. The first flexible sensing layer and the second flexible sensing layer have a resistance difference during the monitoring of soil deformation. The amount of soil deformation is obtained based on the resistance difference. The sign of the resistance difference value of the flexible sensing layer determines whether the soil is settling or bulging. The first flexible sensing layer and the second flexible sensing layer cancel out temperature interference through dual-layer signal differential; Calculate the average curvature and deformation difference between any two electrodes; determine the soil deformation type based on the resistance difference; and obtain the maximum soil deformation measured by the dual-modal flexible sensor by superimposing the deformation differences. The resistance difference between the first and second flexible sensing layers is used to eliminate vertical soil monitoring errors caused by horizontal soil deformation. ； in, This indicates the change in resistance of the first flexible sensing layer. This indicates the change in resistance of the second flexible sensing layer. This represents the change in resistance caused by the vertical deformation of the first flexible sensing layer. This indicates the change in resistance caused by the vertical deformation of the second flexible sensing layer; The average curvature between any two electrodes Represented as: Where D represents the spacing between the first flexible sensing layer and the second flexible sensing layer. R0 represents the thickness of the flexible sensing layer, and R0 represents the initial resistance of the first and second flexible sensing layers. GF This indicates the sensitivity of the flexible sensing layer.

2. The dual-modal flexible sensor according to claim 1, characterized in that, It also includes an encapsulation layer, and the electrode connecting wires extend from the encapsulation layer by a predetermined length.

3. The dual-modal flexible sensor according to claim 1, characterized in that, The thickness of the flexible substrate is 1.5~2.5mm, the thickness of the first flexible sensing layer and the second flexible sensing layer is 0.3~0.8mm, the electrode thickness is 0.3~0.5mm, and the encapsulation layer thickness is 1.5~2.0mm.

4. A dual-modal flexible sensor according to claim 1, characterized in that, The first and second flexible sensing layers are made of a mixture of carbon nanotubes, carbon black, polydimethylsiloxane, and n-hexane, wherein the carbon black and carbon nanotubes are other carbon-based conductive materials, metal-based conductive materials, or piezoelectric materials. The flexible substrate is made of polydimethylsiloxane or hydrogenated styrene-butadiene block copolymer, and the encapsulation layer is made of one of polydimethylsiloxane, polyurethane, or hydrogenated styrene-butadiene block copolymer.

5. A dual-modal flexible sensor according to claim 1 or 4, characterized in that, The first flexible sensing layer and the second flexible sensing layer are placed on the surface of the flexible substrate and heated and cured under a set temperature condition.

6. A dual-modal flexible sensor according to claim 1 or 4, characterized in that, The encapsulation layer is formed using a template method. After encapsulation material is poured onto the flexible substrate, the first flexible sensing layer, the second flexible sensing layer, and the outer side of the electrode, the encapsulation layer is placed horizontally in a drying oven at a set temperature to dry.

7. A method for soil and rock deformation and settlement based on a dual-modal flexible sensor, wherein the dual-modal flexible sensor comprises: A flexible substrate has a first flexible sensing layer on one side and a second flexible sensing layer on the other side; multiple electrodes are arranged at equal intervals in the first and second flexible sensing layers. The flexible substrate, the first flexible sensing layer, the second flexible sensing layer, and the electrodes are encapsulated within an encapsulation layer; The method for deformation and settlement of the rock and soil mass is characterized by comprising: The dual-modal flexible sensor is laid flat inside the soil and connected to an external resistance acquisition instrument and transmission system. Obtain the initial resistance, thickness, spacing, and sensing of the first and second flexible sensing layers, and calculate the average curvature between any two electrodes. The deformation difference between any two electrodes is calculated based on the average curvature and the total length of the flexible sensing layer after deformation. Based on the resistance difference between the first and second flexible sensing layers, the soil deformation type is determined. By superimposing the deformation difference values, the maximum deformation of the soil measured by the dual-mode flexible sensor is obtained. Combined with the deformation observation piles and deformation benchmarks embedded in the soil, the deformation of the soil relative to the initial state is calculated. The resistance difference between the first and second flexible sensing layers is used to eliminate vertical soil monitoring errors caused by horizontal soil deformation. ； in, This indicates the change in resistance of the first flexible sensing layer. This indicates the change in resistance of the second flexible sensing layer. This represents the change in resistance caused by the vertical deformation of the first flexible sensing layer. This indicates the change in resistance caused by the vertical deformation of the second flexible sensing layer; The average curvature between any two electrodes Represented as: Where D represents the spacing between the first flexible sensing layer and the second flexible sensing layer. R0 represents the thickness of the flexible sensing layer, and R0 represents the initial resistance of the first and second flexible sensing layers. GF This indicates the sensitivity of the flexible sensing layer.

8. The method for soil and rock deformation and settlement using a dual-modal flexible sensor according to claim 7, characterized in that, hour, For soil settlement; hour, The soil mass is raised; The formula for calculating the maximum deformation of soil is: ； The difference in deformation between any two electrodes is expressed as: : in, and These represent the electrode designations. for and The initial length between, Use absolute values ​​for calculation.

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