Slope deep slip measuring device with embedded distributed optical fiber FRP (Fiber Reinforce Plastic) structure

Abstract

The invention discloses a slope deep slip measuring device with an embedded distributed optical fiber FRP (Fiber Reinforce Plastic) structure. The measuring device comprises an FRP pipe, a positioning steel ring, a hoop pipe bundle connecting piece, a rubber sealing pipe sleeve, a distributed strain measuring optical fiber and a temperature measuring optical fiber. The two sections of FRP pipes are buckled into the positioning guide grooves in the two ends of the positioning steel ring through the positioning clamping grooves in the two ends to be combined into a whole, then the whole is wrapped with the rubber sealing pipe sleeve, and finally the pipe bundle clamping connecting piece is used for fastening. The fiber reinforced composite material (FRP) is light in weight, high in strength and anti-aging. According to the measuring device, while strain transmission is carried out, it is guaranteed that the middle-layer optical fiber is not prone to being damaged, the mechanical damage resisting effect is remarkable, distributed optical fiber sensing can continuously capture displacement sudden change of any position of the deep portion of a side slope within the length range of the FRP structure, the leak detection risk of point sampling of a traditional inclinometer is avoided, and the measuring accuracy is improved. And the temperature measurement optical cable can compensate the influence of the thermal expansion effect in the measurement structure.

Description

Technical Field

[0001] The invention belongs to the technical field of slope slip measurement, and in particular relates to a slope deep slip measurement device with an embedded distributed optical fiber FRP structure. Background Art

[0002] Deep slope sliding is a core issue in geological disaster prevention and control. It is highly concealed and presents a high risk of sudden collapse. Once unstable, it poses a direct threat to life, property, and the safety of critical infrastructure. Traditional slope monitoring technologies, such as GPS and total stations, focus on surface displacement monitoring but are unable to effectively capture the formation and evolution of deep sliding surfaces. Accurate and continuous monitoring of deep sliding, particularly under complex geological conditions such as accumulation layer landslides and rock-soil interface slip, becomes a key technical bottleneck for landslide early warning and engineering control.

[0003] Common methods for measuring deep slope slip are borehole inclinometers and distributed fiber optic measurement. Traditional borehole inclinometers primarily utilize an inclinometer and an inclinometer casing. The casing is placed in a pre-drilled borehole, and the inclinometer's guide probe is moved along a guide groove within the casing to various depths for measurement. This method measures point by point, accumulating the data to generate the overall displacement. However, if significant deformation occurs at a specific location deep within the slope, the inclinometer probe's descent becomes blocked, preventing further deep displacement measurements.

[0004] Distributed fiber optic measurement, by attaching optical fibers to the wall of the inclinometer, can continuously sense strain distribution along the entire length of the inclinometer, achieving full-depth, blind-spot-free monitoring. This method primarily uses strain along the fiber to invert the bending deformation of the inclinometer, thereby calculating deep sliding displacement. However, existing deep displacement observation devices have the following shortcomings: (1) Existing inclinometer tubes are mostly made of thermoplastic polymer materials (ABS) or polyvinyl chloride (PVC), which have low tensile strength, poor aging resistance, and difficulty adapting to the complex stress environment of deep holes. They are easily damaged during long-term deep underground use and have poor durability.

[0005] (2) Existing technologies often adhere optical fibers to the outer wall of the inclinometer tube or embed them into the surface through grooves. For example, in the "A Slope Deep Deformation Monitoring System Based on Distributed Optical Fibers" (CN201520701412.8), optical fibers are adhered to the surface of the inclinometer tube in a cross-symmetrical manner. Distributed optical fiber sensors installed in this way are prone to generate large local stresses in areas where the rock and soil slip during long-term service, causing the optical fibers to bend or peel, resulting in signal attenuation or even interruption, and affecting the durability of the inclinometer device.

[0006] (3) When laying optical fibers, it is usually necessary to cut grooves and attach optical fiber sensors at the construction site. The construction steps are complicated and the quality of the project is difficult to guarantee. Summary of the Invention

[0007] The present invention aims to provide a device for measuring deep slope slippage using an embedded distributed optical fiber FRP structure. The FRP structure enhances the durability of the distributed optical fiber and FRP, ensuring the durability of the distributed optical fiber, thereby enabling continuous measurement of deep slope rock and soil slippage.

[0008] The device for measuring deep slope slippage with an embedded distributed optical fiber FRP structure comprises an FRP tube, a positioning steel ring, a clamp tube bundle connector, a rubber sealing sleeve, a distributed strain measurement optical fiber, and a temperature measurement optical fiber. Two sections of FRP tube are snapped into the positioning guide grooves at both ends of the positioning steel ring through positioning slots at both ends, assembled into a whole, then wrapped with a rubber sealing sleeve, and finally fastened with a clamp tube bundle connector.

[0009] The FRP tube consists of an inner base tube and an outer fiber winding layer; the winding direction of the fiber winding layer and the longitudinal angle between the inner base tube and the fiber winding layer are in the range of (0°, 90°), preferably [50°, 90°].

[0010] The fiber winding layer is made of one or more of basalt fiber, carbon fiber, aramid fiber, and glass fiber impregnated with a resin matrix; the resin matrix is ​​vinyl resin, epoxy resin, polyurethane resin, or phenolic resin.

[0011] The inner base tube is solidified and formed in one step by adopting a pultrusion process, and the outer fiber winding layer is solidified and formed in one step by adopting a winding process.

[0012] The inner wall of the inner layer base tube is orthogonally symmetrically laid with four distributed strain measurement optical fibers at 0°, 90°, 180°, and 270°, and one temperature measurement optical fiber is laid at 45°.

[0013] The FRP tube is embossed with a diamond-shaped pattern at each end, with a pattern depth of no less than 0.5 mm and a pattern pitch of no more than 2 mm. The pattern increases friction and enhances the stability of the connectors.

[0014] The two ends of the FRP tube are provided with positioning grooves at 135°, 225° and 315°, which match the annular positioning guide grooves provided at the two ends of the positioning steel ring.

[0015] The positioning guide groove is provided with positioning protrusions at 135°, 225° and 315° to match the FRP pipe end.

[0016] The inner side wall of the positioning guide groove is provided with holes at 0°, 45°, 90°, 180° and 270° for optical fibers to pass through.

[0017] The positioning steel ring is made of austenitic stainless steel.

[0018] The rubber sealing sleeve is made of weather-resistant neoprene material, which can ensure the life and durability in long-term underground corrosive environment.

[0019] The axial length of the rubber sealing sleeve shall not be less than the sum of twice the outer diameter of the FRP pipe and the axial length of the positioning steel ring: L 1≥ 2 D + h Where, L 1 is the axial length of the rubber sealing sleeve, D is the outer diameter of the FRP pipe, h is the axial length of the positioning steel ring.

[0020] The clamp pipe bundle connector is made of austenitic stainless steel.

[0021] The axial length of the clamp pipe bundle connector is consistent with the axial length of the rubber sealing pipe sleeve.

[0022] The fastening nuts of the clamp tube bundle connector are double nuts, the inner side of which is a self-locking nut and the outer side is a common nut.

[0023] Beneficial effects of the present invention: 1. Lightweight, high-strength, and aging-resistant. Fiber-reinforced plastic (FRP) is resistant to acid, alkali, and salt spray corrosion, making it suitable for harsh environments such as humid and underground environments. It avoids the aging and breakage problems of traditional PVC or ABS inclinometer tubes.

[0024] 2. FRP material is highly strong. The inner base tube provides axial tensile strength, ensuring tube rigidity. The outer fiber winding layer provides compressive strength, resisting lateral pressure from the underground rock and soil. This material structure not only transmits strain but also prevents damage to the optical fibers in the middle layer, providing excellent resistance to mechanical damage.

[0025] 3. Distributed fiber optic sensing can continuously capture sudden displacement changes at any location deep within the slope within the length of the FRP structure, avoiding the risk of missed detection by traditional inclinometers that use point sampling. The temperature measurement cable can also compensate for the effects of thermal expansion in the measurement structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an overall schematic diagram of the FRP structure proposed in an embodiment of the present invention.

[0027] Figure 2 A detailed diagram of the diamond-shaped roller embossing at the end of the FRP structure according to an embodiment of the present invention; Figure 3 This is a diagram of the FRP structure positioning steel ring proposed in an embodiment of the present invention; Figure 4 This is a cross-sectional schematic diagram of the FRP structural positioning steel ring according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the FRP structural clamp tube bundle proposed in an embodiment of the present invention; Figure 6 This is a schematic diagram of the FRP structural rubber sleeve according to an embodiment of the present invention; In the figure, 1-FRP tube, 2-distributed strain measurement optical fiber, 3-positioning slot, 4-diamond roller embossing, 5-temperature measurement optical fiber, 6-positioning steel ring, 7-positioning guide groove, 8-positioning protrusion, 9-hole, 10-clamp tube bundle connector, 11-clamp tube bundle connector installation positioning steel ring section, 12-fastening bolt, 13-rubber sealing sleeve. DETAILED DESCRIPTION

[0028] In order to ensure that professionals in relevant fields can better understand the purpose, operating steps and advantages of this patent, this patent is described in detail through drawings and specific embodiments. At the same time, this patent is not limited to the description in the specific implementation methods. Without violating the connotation of this patent, it can be improved and applied in various other ways different from this embodiment.

[0029] It should be noted that the "inside" and "outside" used in the specific embodiments refer to the direction away from the center of the component. The terms "embedded", "fixed", "circumferential", "radial", etc. used herein are not exclusive expressions and are only used for specific purposes. Example 1

[0030] See Figure 1-Figure 5 The slope deep slip measurement device with an embedded distributed optical fiber FRP structure includes: an FRP tube 1, a positioning steel ring 6, a clamp tube bundle connector 10, a rubber sealing tube sleeve 13, four distributed strain measurement optical fibers 2 and one temperature measurement optical fiber 5; the two sections of FRP tube are connected and fixed by a positioning steel ring, a rubber sealing tube sleeve and a clamp tube bundle connector.

[0031] When preparing the FRP tube 1, the inner base tube is first prepared. Pre-prepared carbon fiber or glass fiber yarn is evenly impregnated with a resin matrix, such as unsaturated polyester, epoxy resin, or vinyl ester. This is then fed into an extruder for high-temperature, high-pressure curing and continuous extrusion. The inner diameter is determined based on the actual slip state of the slope being measured. After cooling, the FRP inner base tube is cut into 2-meter-long sections.

[0032] Five microgrooves, 1 mm wide and 0.5 mm deep, were laser-etched into the inner base tube at 0°, 45°, 90°, 180°, and 270°. Four distributed strain measurement optical fibers (2) were embedded in the microgrooves at 0°, 90°, 180°, and 270°, respectively, while a temperature measurement optical fiber (5) was embedded in the microgrooves at 45°. UV-curable adhesive was used for temporary fixation, and a flexible polyurethane coating was sprayed on the fibers to cover and fill the grooves, protecting them during fabrication. A 15 cm length of optical fiber was reserved at each end of the inner base tube for fiber fusion splicing when connecting the FRP tubes.

[0033] A fiber wrapping layer is wound around the outer layer of the inner base tube. This fiber wrapping layer, made of carbon fibers impregnated with epoxy resin, is spirally or hoop-wound around the inner base tube. To ensure a tight connection and increase friction at the joint, a diamond-shaped roller embossing pattern (4) is applied to both ends of the FRP tube, extending within a range equal to the outer diameter of the FRP tube. The pattern has a depth of 0.5 mm and a pitch of 2 mm.

[0034] The FRP tube has positioning slots at 135°, 225°, and 315° on both ends, measuring 1 cm deep and 1 cm wide. These slots mate with the circular positioning guide grooves 7 on both ends of the positioning steel ring. The two sections of FRP tube snap into the positioning guide grooves at both ends of the positioning steel ring through the positioning slots, forming a single unit. The positioning steel ring 6 is 5 cm tall, with an inner diameter 5 mm smaller than the inner diameter of the FRP tube and an outer diameter 5 mm larger than the outer diameter of the FRP tube. Positioning protrusions 8, measuring 5 mm high and 1 cm wide, are located within the positioning guide groove 7 at 135°, 225°, and 315°, matching the ends of the FRP tube. Holes 9, with a diameter of 2 mm, are provided on the inner wall of the positioning guide groove at 0°, 45°, 90°, 180°, and 270°, connecting inward at 45° to the center axis of the circular ring.

[0035] The positioning steel ring is wrapped with a rubber sealing sleeve and finally fastened with a clamp tube bundle connector. The positioning steel ring and the clamp tube bundle connector are made of austenitic stainless steel, and the rubber sealing sleeve is made of weather-resistant chloroprene rubber. The axial length of the rubber sealing sleeve is not less than twice the outer diameter of the FRP pipe and the sum of the axial lengths of the positioning steel ring to ensure sufficient friction to provide stable connectivity. The axial length of the clamp tube bundle connector is consistent with the axial length of the rubber sealing sleeve. The fastening nut of the clamp tube bundle connector is a double nut. First tighten the self-locking nut to the tightening torque, and then tighten the ordinary nut to 60% to 70% of the tightening torque.

[0036] On-site installation: Splice the FRP tubes according to the required slope depth. First, insert the positioning slots 3 at the ends of the two FRP tubes 1 into the positioning steel rings 6. Then, pass the five optical fibers of the FRP tubes 1 through the holes 9 of the positioning steel rings 6. Use a fiber optic fusion splicer to heat-seal the corresponding optical fibers of the two FRP tubes into one. Align the positioning steel rings 6 with the FRP tubes and buckle them. Wrap the joint with the rubber sealing sleeve 13. Finally, put on the clamp tube bundle connector 10 and tighten the nut to complete the connection.

Claims

1. A slope deep slip measurement device with an embedded distributed optical fiber FRP structure, characterized in that: The measuring device includes: an FRP tube, a positioning steel ring, a clamp tube bundle connector, a rubber sealing sleeve, a distributed strain measurement optical fiber, and a temperature measurement optical fiber; two sections of FRP tube are respectively snapped into the positioning guide grooves at both ends of the positioning steel ring through the positioning slots at both ends to be combined into a whole, then wrapped with the rubber sealing sleeve, and finally fastened with the clamp tube bundle connector.

2. The device for measuring deep slope slippage with an embedded distributed optical fiber FRP structure according to claim 1, characterized in that: The FRP tube consists of an inner base tube and an outer fiber winding layer; the winding direction of the fiber winding layer and the longitudinal angle between the inner base tube and the fiber winding layer are in the range of (0°, 90°), preferably [50°, 90°].

3. The device for measuring deep slope slippage with an embedded distributed optical fiber FRP structure according to claim 2, characterized in that: The fiber winding layer is made of one or more of basalt fiber, carbon fiber, aramid fiber, and glass fiber impregnated with a resin matrix; the resin matrix is ​​vinyl resin, epoxy resin, polyurethane resin, or phenolic resin.

4. The device for measuring deep slope slippage with an embedded distributed optical fiber FRP structure according to claim 2, characterized in that: The inner wall of the inner layer base tube is orthogonally symmetrically laid with four distributed strain measurement optical fibers at 0°, 90°, 180°, and 270°, and one temperature measurement optical fiber is laid at 45°.

5. The device for measuring deep slope slippage with an embedded distributed optical fiber FRP structure according to claim 1, characterized in that: A circle of diamond-shaped roller embossing is respectively pressed on both ends of the FRP tube, the embossing has a depth of not less than 0.5 mm and a pitch of not more than 2 mm.

6. The device for measuring deep slope slippage with an embedded distributed optical fiber FRP structure according to claim 1, characterized in that: Positioning slots are provided at 135°, 225°, and 315° at both ends of the FRP tube, which match the annular positioning guide grooves provided at both ends of the positioning steel ring; holes are provided on the inner wall of the positioning guide groove at 0°, 45°, 90°, 180°, and 270° for the optical fiber to pass through.

7. The device for measuring deep slope slippage with an embedded distributed optical fiber FRP structure according to claim 6, characterized in that: The positioning guide groove is provided with positioning protrusions at 135°, 225° and 315° to match the FRP pipe end.

8. The device for measuring deep slope slippage with an embedded distributed optical fiber FRP structure according to claim 1, characterized in that: The axial length of the rubber sealing sleeve shall not be less than the sum of twice the outer diameter of the FRP pipe and the axial length of the positioning steel ring: L 1≥ 2 D + h Where, is the axial length of the rubber sealing sleeve, is the outer diameter of the FRP pipe, h is the axial length of the positioning steel ring.

9. The device for measuring deep slope slippage with an embedded distributed optical fiber FRP structure according to claim 1, characterized in that: The axial length of the clamp pipe bundle connector is consistent with the axial length of the rubber sealing pipe sleeve.

10. The device for measuring deep slope slippage with an embedded distributed optical fiber FRP structure according to claim 1, characterized in that: The fastening nuts of the clamp tube bundle connector are double nuts, the inner side of which is a self-locking nut and the outer side is a common nut.

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