A shield tunneling ground surface settlement automatic monitoring device

Abstract

The utility model relates to a kind of shield surface subsidence automatic monitoring devices, belong to surface subsidence monitoring technical field.The shield surface subsidence automatic monitoring device, comprising: the number of not less than two fiber grating sensors, the opposite end of adjacent two fiber grating sensors is connected by fusion;Protection mechanism, the number of fiber grating sensors is set as n (n≥2), the number of protection mechanism is then n-1 (n≥2), and the protection mechanism is sleeved on the surface of fiber grating sensor;Through the cooperation design of the ring of protection mechanism and the U-shaped section of sealing ring, double-sealing barrier is formed, effectively blocks the infiltration of external moisture and corrosive medium into the fusion of fiber grating sensor.Fluorine rubber sealing ring is combined with corrosion-resistant coating, which significantly improves weather resistance and chemical stability, adapts to underground humid, acid-base environment, solves the problem of UV glue easy hydrolysis cracking, prolongs the service life of monitoring device.

Description

Technical Field

[0001] This utility model relates to the field of surface subsidence monitoring technology, and in particular to an automatic monitoring device for surface subsidence of shield tunnels. Background Technology

[0002] Fiber Bragg grating sensors are optical sensing devices based on the principle of fiber Bragg gratings, specifically designed for monitoring ground settlement during tunnel boring machine (TBM) construction. They measure changes in light wavelength to invert vertical or horizontal displacement of the ground, achieving high-precision, distributed real-time monitoring and automatically transmitting the data to a platform to aid in risk warning and construction control.

[0003] Currently, these sensors are mostly installed in shallow trenches on the ground, suitable for loose soil layers. Their installation requires welding multiple sensors in series and sealing the welds with UV adhesive. However, UV adhesive is prone to hydrolysis in damp or alkaline soil layers, increasing the probability of cracking and protective failure, making it difficult to meet long-term monitoring needs. Utility Model Content

[0004] Therefore, it is necessary to provide an automatic monitoring device for surface settlement of tunnel boring machines, which addresses the problem that existing fiber optic grating sensors with UV-sealed connections are easily damaged by the surrounding environment and cannot meet long-term monitoring requirements.

[0005] An automatic surface settlement monitoring device for tunnel boring machines includes:

[0006] There are at least two fiber Bragg grating sensors, with the opposite ends of two adjacent fiber Bragg grating sensors connected in series by fusion splicing;

[0007] The number of fiber Bragg grating sensors is set to n (n≥2), and the number of protection mechanisms is n-1 (n≥2). The protection mechanism is sleeved on the surface of the fiber Bragg grating sensor, and the fusion splice of the fiber Bragg grating sensor is located on the inner side of the protection mechanism.

[0008] In one embodiment, the protection mechanism includes a ring sleeve disposed outside the fiber Bragg grating sensor fusion splice, the upper surface of the ring sleeve having an injection hole, and the interior of the ring sleeve being filled with adhesive.

[0009] In one embodiment, both openings of the ring are fixedly connected with sealing rings, which are sleeved on the surface of the fiber Bragg grating sensor, and the two sealing rings are symmetrically distributed on both sides of the fusion splice of the fiber Bragg grating sensor.

[0010] In one embodiment, the cross-sectional shape of the connection between the sealing ring and the ring sleeve is U-shaped, and the openings of the U-shaped cross-sections of both the sealing ring and the ring sleeve face away from the fiber optic grating sensor.

[0011] In one embodiment, the inner diameter of the ring opening and the diameter of the sealing ring are both larger than the diameter of the fiber Bragg grating sensor fusion joint.

[0012] In one embodiment, the sealing ring has an internal cavity, and the cavity is annular in shape.

[0013] In one embodiment, the sealing ring is a fluororubber component, and the surface of the sealing ring facing away from the fiber Bragg grating sensor fusion joint is coated with an anti-corrosion coating.

[0014] In one embodiment, the ring is a transparent acrylic material component, and the adhesive is a UV-curable adhesive material component.

[0015] In one embodiment, there are two injection holes, which are symmetrically distributed on both sides of the fiber Bragg grating sensor fusion splice.

[0016] Beneficial effects

[0017] The aforementioned automatic surface settlement monitoring device for tunnel boring machines utilizes a double-sealed barrier design, where the protective ring and sealing ring's U-shaped cross-section work together to effectively prevent external moisture and corrosive media from penetrating the fiber optic grating sensor's weld joint. The fluororubber sealing ring, combined with an anti-corrosion coating, significantly enhances weather resistance and chemical stability, adapting to damp, acidic, and alkaline underground environments. This solves the problem of UV adhesive's tendency to hydrolyze and crack, extending the monitoring device's service life.

[0018] The elastic buffer design of the annular cavity inside the sealing ring can compensate for the tensile stress on the optical fiber caused by minor soil displacement, reducing the risk of false alarms caused by mechanical deformation of the sensor. Combined with a transparent acrylic ring and a dual-injection-hole structure, it ensures uniform UV adhesive filling while facilitating operation and visualization, achieving a balance between reliable weld protection and ease of construction. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0021] Figure 2 This is a schematic diagram of a partial structure in this utility model;

[0022] Figure 3This is a cross-sectional schematic diagram of a partial structure in this utility model;

[0023] Figure 4 This is a schematic diagram of the ring sleeve in this utility model;

[0024] Figure 5 This is an exploded view of the sealing ring in this utility model.

[0025] Figure label:

[0026] 100 Fiber Bragg grating sensor; 200 Protection mechanism; 210 Ring; 211 Injection hole; 220 Sealing ring; 221 Cavity. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0028] The following is combined Figure 1 - Figure 5 This invention describes an automatic monitoring device for surface settlement in tunnel boring machines.

[0029] In one embodiment, an automatic surface settlement monitoring device for tunnel boring machines includes:

[0030] There are no fewer than two fiber Bragg grating sensors 100, and the opposite ends of two adjacent fiber Bragg grating sensors 100 are connected in series by fusion splicing.

[0031] The number of fiber Bragg grating sensors 100 is set to n (n≥2), and the number of protection mechanisms 200 is n-1 (n≥2). The protection mechanism 200 is sleeved on the surface of the fiber Bragg grating sensor 100, and the fusion splice of the fiber Bragg grating sensor 100 is located on the inner side of the protection mechanism 200.

[0032] like Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the protection mechanism 200 includes a ring 210, which is disposed on the outside of the fusion splice of the fiber optic grating sensor 100. An injection hole 211 is provided on the upper surface of the ring 210, and the inside of the ring 210 is filled with glue.

[0033] Both openings of the ring 210 are fixedly connected with sealing rings 220. The sealing rings 220 are sleeved on the surface of the fiber Bragg grating sensor 100, and the two sealing rings 220 are symmetrically distributed on both sides of the fusion splice of the fiber Bragg grating sensor 100.

[0034] The cross-sectional shape of the connection between the sealing ring 220 and the sleeve 210 is U-shaped. The openings of the U-shaped cross sections of the sealing ring 220 and the sleeve 210 both face away from the fiber optic grating sensor 100. The U-shaped cross section connecting the sleeve 210 can enhance the fit between the sealing ring 220 and the sleeve 210, forming a double sealing barrier to prevent glue leakage and external water seepage.

[0035] The inner diameter of the opening of the ring 210 and the diameter of the sealing ring 220 are both larger than the diameter of the fusion joint of the fiber optic grating sensor 100.

[0036] The sealing ring 220 has a cavity 221 inside. The cavity 221 is circular in shape. The design of the internal circular cavity 221 can provide elastic buffering, compensate for the tensile stress of small displacement of the soil on the optical fiber, and reduce the risk of false alarm by the sensor.

[0037] The sealing ring 220 is a fluororubber material component. The surface of the sealing ring 220 facing away from the fiber optic grating sensor 100 is coated with an anti-corrosion coating. The design of fluororubber material + anti-corrosion coating can improve weather resistance and chemical stability, adapt to underground humid and acidic / alkaline environments, and extend service life.

[0038] The ring 210 is a transparent acrylic material component, and the adhesive is a UV-curable adhesive material component. The ring 210, designed with transparent acrylic material, not only facilitates observation of the internal adhesive filling, but also allows ultraviolet light to penetrate to cure the UV adhesive, ensuring operational visualization and curing reliability.

[0039] There are two injection holes 211, which are symmetrically distributed on both sides of the fusion joint of the fiber optic grating sensor 100. The symmetrical design of the two injection holes 211 can improve the glue filling efficiency, avoid air bubble residue, and ensure that the fusion joint is uniformly wrapped.

[0040] The installation steps for the automatic surface settlement monitoring device for tunnel boring machines are as follows:

[0041] I. Preparations before laying

[0042] Geological survey and route planning: Monitoring sections are set up on both sides of the shield tunnel axis, and areas with uniform soil layers that are not easily crushed by machinery are prioritized, while avoiding underground pipelines, seepage areas and future construction passages to avoid later damage.

[0043] Fiber Bragg grating sensor 100 selection: Select an FBG strain sensor with armor protection, such as the MicronOptics OS3600 series.

[0044] Auxiliary materials: fine sand, bentonite (for waterproofing), PVC protective pipe, positioning marker posts.

[0045] Tools: Mini slotting machine, fiber optic fusion splicer, OTDR tester, demodulator.

[0046] II. Shallow trench excavation and sensor installation

[0047] Slotting construction: Mechanically slot along the designed path, level the bottom of the slot and lay a 2cm-5cm thick fine sand pad, and maintain a curvature radius of ≥20cm at the bends to avoid fiber micro-bending loss.

[0048] Series arrangement: The protection mechanism 200 is pre-sleeved onto the wire of the fiber Bragg grating sensor 100. Then, two adjacent fiber Bragg grating sensors 100 are fused together to form a chain. The spacing is set according to the monitoring requirements. Then, the protection mechanism 200 is slid to cover the fusion joint of the fiber Bragg grating sensor 100, and it is ensured that the value of the injection hole 211 on the ring 210 is facing upward. Then, UV curing adhesive is filled into the inside of the ring 210 through a disposable syringe and the injection hole 211. Finally, the ring 210 is cured by passing a UV lamp through the transparent acrylic material.

[0049] Fixing and Protection: The fiber optic grating sensor is fixed to the bottom of the trench with stainless steel clamps at 100 nodes to ensure close contact with the soil; the optical fiber is protected by PVC pipe, the outside of the pipe is wrapped with waterproof tape, and the joints are sealed.

[0050] Backfilling and compaction in layers: First, backfill with fine sand of a specified thickness to cover the fiber optic grating sensor 100, and then lightly compact it manually; the upper layer is backfilled with the original soil in layers to avoid mechanical compaction.

[0051] III. Data Cable and Outlet Processing: A specified length of redundant optical fiber is reserved at both ends of the monitoring area and coiled into a straight loop and buried in the maintenance well. When crossing roads or construction areas, steel conduits must be installed for protection. Both ends of the conduits are sealed with fireproof sealant. The terminal optical fiber is connected to the demodulator and the loss is tested using an OTDR. A lightning protection module is installed in the monitoring station to prevent surge damage to the equipment.

[0052] IV. Calibration and Initial Data Acquisition

[0053] Baseline establishment: After installation, allow the sensor to stand for 24 hours, collect initial wavelength data as a baseline, and record the ambient temperature simultaneously. Conduct artificial loading tests (such as applying a known load locally) to verify whether the sensor sensitivity and range meet expectations.

[0054] Temperature compensation settings: Deploy independent temperature sensors in the monitoring area, or use dual gratings (one to measure strain, and one to sense temperature only) for real-time compensation.

[0055] The operation process of the automatic surface settlement monitoring device for tunnel boring machines is as follows:

[0056] Data acquisition: 100 fiber optic grating sensors arranged in series monitor changes in surface strain in real time, and the signals are transmitted to the demodulator via optical fiber.

[0057] Signal transmission and processing: The demodulator converts the grating wavelength offset into settlement data and transmits it to the monitoring system. The system automatically compares the data with the initial reference value (data after 24 hours of static placement after installation) and combines it with compensation data from temperature sensors or dual gratings to eliminate the influence of temperature.

[0058] Settlement analysis: The system analyzes wavelength changes, calculates settlement values ​​at each monitoring point, and generates settlement curves or contour maps. If settlement exceeds a threshold, an early warning is triggered.

[0059] Data output and storage: Monitoring data is displayed and stored in real time, supporting historical queries and trend analysis, providing a basis for adjustments to tunnel boring machine construction.

[0060] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. An automatic monitoring device for surface settlement of a shield tunnel, characterized in that, include: There are at least two fiber Bragg grating sensors (100), and the opposite ends of two adjacent fiber Bragg grating sensors (100) are connected in series by fusion splicing; The number of fiber Bragg grating sensors (100) is set to n (n≥2), and the number of protection mechanisms (200) is n-1 (n≥2). The protection mechanism (200) is sleeved on the surface of the fiber Bragg grating sensor (100), and the fusion splice of the fiber Bragg grating sensor (100) is located on the inner side of the protection mechanism (200). The protection mechanism (200) includes a ring (210), which is located outside the fusion splice of the fiber optic grating sensor (100). An injection hole (211) is provided on the upper surface of the ring (210), and the inside of the ring (210) is filled with glue.

2. The automatic surface settlement monitoring device for shield tunneling according to claim 1, characterized in that, The two openings of the ring (210) are fixedly connected with sealing rings (220). The sealing rings (220) are sleeved on the surface of the fiber Bragg grating sensor (100). The two sealing rings (220) are symmetrically distributed on both sides of the fusion joint of the fiber Bragg grating sensor (100).

3. The automatic surface settlement monitoring device for shield tunneling according to claim 2, characterized in that, The cross-sectional shape of the connection between the sealing ring (220) and the ring sleeve (210) is U-shaped, and the openings of the U-shaped cross sections of the sealing ring (220) and the ring sleeve (210) are both facing away from the fiber optic grating sensor (100).

4. The automatic surface settlement monitoring device for shield tunneling according to claim 3, characterized in that, The inner diameter of the opening of the ring (210) and the diameter of the sealing ring (220) are both larger than the diameter of the fusion joint of the fiber optic grating sensor (100).

5. The automatic surface settlement monitoring device for shield tunneling according to claim 2, characterized in that, The sealing ring (220) has a cavity (221) inside, and the cavity (221) is annular in shape.

6. The automatic surface settlement monitoring device for shield tunneling according to claim 2, characterized in that, The sealing ring (220) is a fluororubber material component, and the surface of the sealing ring (220) facing away from the fiber optic grating sensor (100) is coated with an anti-corrosion coating.

7. The automatic surface settlement monitoring device for shield tunneling according to claim 1, characterized in that, The ring (210) is a transparent acrylic material component, and the adhesive is a UV-curable adhesive material component.

8. The automatic surface settlement monitoring device for shield tunneling according to claim 1, characterized in that, There are two injection holes (211), which are symmetrically distributed on both sides of the fusion splice of the fiber optic grating sensor (100).

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