A multi-parameter optical fiber sensor for formation awareness

Abstract

The application provides a multi-parameter optical fiber sensor for stratum sensing, and belongs to the field of measuring equipment. The sensor comprises a compression rod, a sensing column sleeved outside the compression rod, and three optical fibers. An optical fiber groove is formed in the rod wall of the compression rod along the axial direction, one end of a strain optical fiber is connected with an optical fiber demodulator, the other end extends downward along a through hole of the sensing column and is pasted in the optical fiber groove. A temperature optical fiber and a stress optical fiber are uniformly wound on the column of the sensing column in a spiral manner with a constant interval L from top to bottom. The application can collect different stratum parameters by installing different sensing optical fibers, realize multi-parameter measurement of strata, and only needs to be placed into the soil to be measured, and the wavelength change measured by the optical fiber demodulator connected with the optical fiber can be used to convert the stratum information of the area, the equipment can be repeatedly used, the operation is simple, and the cost is low.

Description

Technical Field

[0001] This invention relates to the field of measurement equipment, and more specifically, to a multi-parameter fiber optic sensor for ground sensing. Background Technology

[0002] Ground parameter sensing is an indispensable part of geological construction engineering. The temperature, confining pressure, and vertical strain experienced by structures in deep underground soil are crucial to their operational status and directly affect their safety. Therefore, accurate measurement of the temperature, confining pressure, and vertical strain of deep soil is of great significance, and several sensing devices currently exist.

[0003] For example, Chinese patent document CN118777368A discloses an in-situ distributed measurement system and method for soil heat flux based on DTS, which uses DTS measuring tubes to collect and calculate the temperature, thermal conductivity and moisture content distribution of soil, but the device lacks the measurement of confining pressure and strain.

[0004] Chinese patent document CN220153496U discloses a deep soil displacement monitoring device based on MEMS sensors, which measures the displacement of deep soil through MEMS sensors, but the device can only collect displacement data.

[0005] Chinese patent document CN115404840B discloses a smart geotextile for damage perception and disaster early warning based on deep learning. It collects data such as stress, strain, temperature and moisture content of soil through a deep learning module chip group. However, this geotextile is only suitable for shallow roadbeds and other locations, and its application scope is limited.

[0006] Chinese patent document CN117759229A discloses a dynamic monitoring and sensing system and method for temperature field in deep metal strata. The system collects temperature data by setting temperature probes in various temperature monitoring boreholes in the target roadway, but the probes can only collect temperature data.

[0007] Chinese patent document CN110567519B discloses a measuring unit for monitoring the pressure and water content of soil in deep boreholes within landslide bodies. However, this unit cannot measure temperature and strain.

[0008] Chinese patent document CN116242986A discloses a soil mechanics testing rod and a system and method for determining the physical and mechanical state of surface soil in a specific area. This system is used to measure parameters such as shear strength, stress state, and pore water pressure of soil within a defined area. The device requires the installation of multiple sensors of various types, resulting in a complex structure, difficult operation, and high monitoring costs.

[0009] In summary, existing monitoring equipment suffers from problems such as incomplete monitoring parameters, high cost, and cumbersome operation. Based on this, the present invention designs a multi-parameter fiber optic sensor for ground sensing. Summary of the Invention

[0010] The technical problem to be solved by this invention is the deficiency of the existing technology. The purpose is to achieve accurate sensing of multiple parameters of the formation in response to the deficiency of the existing technology.

[0011] To achieve the above objectives, the present invention proposes to adopt the following technical solution.

[0012] A multi-parameter fiber optic sensor for ground sensing includes a main structure, strain fiber, temperature fiber, stress fiber, and fiber demodulator. The main structure includes a compression rod, a sensing column, an upper protective cover, and a lower protective cover.

[0013] The compression rod is a solid round rod with an optical fiber groove on its wall along the axial direction, and external threads A are opened on the head and tail of the compression rod.

[0014] The sensing column is a hollow cylinder, the hollow part of which is a through hole along the axial direction, and the diameter of the through hole is adapted to the diameter of the compression rod; an external thread B is opened on the outer wall of the tail of the sensing column.

[0015] Both the upper and lower protective covers are semi-hollow cylinders, with the inner diameter of the hollow portion matching the outer diameter of the sensing column, and an internal thread hole matching the external thread A is opened at the center of the inner bottom surface of each cover; the hollow portion of the upper protective cover has a lead hole that penetrates the inner and outer walls, and the inner wall of the hollow portion of the lower protective cover has an internal thread matching the external thread B.

[0016] The compression rod is fitted into the sensing column through a through hole, and its tail is locked into the internal thread hole of the lower protective cover through an external thread A. The tail of the sensing column is screwed into the internal thread through an external thread B, so that the sensing column is completely seated in the lower protective cover. The head of the compression rod is screwed into the internal thread hole of the upper protective cover through an external thread A, so that the upper protective cover is installed on the upper part of the sensing column, and a gap H is left between the upper end face of the sensing column and the inner bottom face of the upper protective cover.

[0017] One end of the strained optical fiber is connected to the optical fiber demodulator, and the other end enters the upper protective cover through the lead hole of the upper protective cover, extends downward along the through hole, and is pasted in the optical fiber groove until the end of the optical fiber groove.

[0018] The temperature fiber and the stress fiber maintain a constant spacing L, with one end of each fiber connected to the fiber demodulator, and the other end of each fiber evenly wound in a spiral manner from top to bottom around the sensing column.

[0019] Preferably, the gap H is greater than 2cm, and the gap H is adjusted by screwing the external thread A of the compression rod head to the internal thread hole of the upper protective cover.

[0020] Preferably, after the main structure and the three types of optical fibers are installed, a plastic protective sleeve is placed over the multi-parameter optical fiber sensor.

[0021] Preferably, the constant spacing L is 0.8cm-2cm.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) The present invention designs a multi-parameter fiber optic sensor for ground sensing, which measures ground parameters through fiber optics and has high measurement accuracy.

[0024] (2) This invention achieves multi-parameter measurement of the formation by installing different sensing optical fibers to collect different formation parameters.

[0025] (3) The present invention only requires the device to be lowered into the soil to be tested. The stratum information of the area can be calculated by the wavelength change measured by the fiber demodulator connected to the sensing fiber. The device is reusable, simple to operate and low in cost. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the multi-parameter fiber optic sensor structure in an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the upper protective cover structure in an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the lower protective cover structure in an embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of the compression rod structure in an embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the sensing column structure in an embodiment of the present invention.

[0031] Reference numerals: 1. Upper protective cover; 2. Compression rod; 3. Sensing column; 4. Strain fiber; 5. Internal threaded hole; 6. Lead wire hole; 7. External thread A; 8. Fiber optic groove; 9. Lower protective cover; 10. Temperature fiber; 11. Stress fiber; 12. Through hole; 13. Plastic protective sleeve; 14. External thread B; 15. Internal thread. Detailed Implementation

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

[0033] Figure 1This is a schematic diagram of the multi-parameter fiber optic sensor structure in an embodiment of the present invention. Figure 2 This is a schematic diagram of the upper protective cover structure in an embodiment of the present invention. Figure 3 This is a schematic diagram of the lower protective cover structure in an embodiment of the present invention. Figure 4 This is a schematic diagram of the compression rod structure in an embodiment of the present invention. Figure 5 This is a schematic diagram of the sensing column structure in an embodiment of the present invention.

[0034] As can be seen from the above figures, the present invention provides a multi-parameter fiber optic sensor for stratum sensing, including a main structure, a strain fiber 4, a temperature fiber 10, a stress fiber 11, and a fiber optic demodulator. The main structure includes a compression rod 2, a sensing column 3, an upper protective cover 1, and a lower protective cover 9.

[0035] The compression rod 2 is a solid round rod with an optical fiber groove 8 cut along the axial direction on its wall, and external threads A7 cut on the head and tail of the compression rod 2.

[0036] The sensing column 3 is a hollow cylinder, and its hollow part is a through hole 12 along the axial direction. The diameter of the through hole 12 is adapted to the diameter of the compression rod 2. An external thread B14 is opened on the outer wall of the tail of the sensing column 3.

[0037] Both the upper protective cover 1 and the lower protective cover 9 are semi-hollow cylinders. The inner diameter of the hollow part is adapted to the outer diameter of the sensing column 3, and an internal thread hole 5 adapted to the external thread A7 is opened at the center of the inner bottom surface of each. The hollow part of the upper protective cover 1 has a lead hole 6 that penetrates the inner and outer walls, and the inner wall of the hollow part of the lower protective cover 9 has an internal thread 15 adapted to the external thread B14.

[0038] The compression rod 2 is fitted into the sensing column 3 through the through hole 12, and its tail is locked in the internal thread hole 5 of the lower protective cover 9 through the external thread A7. The tail of the sensing column 3 is screwed into the internal thread 15 through the external thread B14, so that the sensing column 3 is completely seated in the lower protective cover 9. The head of the compression rod 2 is screwed into the internal thread hole 5 of the upper protective cover 1 through the external thread A7, so that the upper protective cover 1 is installed on the upper part of the sensing column 3, and a gap H is left between the upper end face of the sensing column 3 and the inner bottom face of the upper protective cover 1.

[0039] In this embodiment, the gap H is greater than 2cm, and the gap H is adjusted by screwing the external thread A7 of the compression rod 2 head to the internal thread hole 5 of the upper protective cover 1.

[0040] In this embodiment, the internal threaded hole 5 of the upper protective cover 1 and the internal threaded hole 5 of the lower protective cover 9 have the same thread, but the depth of the hole is different. That is, the internal threaded hole 5 of the upper protective cover 1 is deeper than the internal threaded hole 5 of the lower protective cover 9. In this way, the gap H can be adjusted by screwing the external thread A7 of the head of the compression rod 2 to the internal threaded hole 5 of the upper protective cover 1.

[0041] One end of the strain fiber 4 is connected to the fiber demodulator, and the other end enters the upper protective cover 1 through the lead hole 6, extends downward along the through hole 12, and is pasted in the fiber groove 8 until the tail end of the fiber groove 8.

[0042] In actual operation, firstly, the optical fiber 4 is pasted into the optical fiber groove 8 of the compression rod 2, then the compression rod 2 is installed in the sensing column 3, then the tail of the compression rod 2 and the tail of the sensing column 3 are screwed to the lower protective cover 9 respectively, and finally the protective cover 1 is installed and the optical fiber is led out through the lead hole 6.

[0043] The temperature fiber 10 and the stress fiber 11 maintain a constant spacing L. One end of each fiber is connected to the fiber demodulator, and the other end is wound evenly around the sensing column 3 from top to bottom in a spiral manner.

[0044] In this embodiment, the constant spacing L is 0.8cm-2cm. Specifically, L=1cm was chosen.

[0045] In this embodiment, after the main structure and the three types of optical fibers are installed, a plastic protective sleeve 13 is placed over the multi-parameter optical fiber sensor. The function of this plastic protective sleeve is to fix the two types of optical fibers wound around the sensing column 3 and to prevent the entry of external debris and avoid interference.

Claims

1. A multi-parameter fiber optic sensor for ground sensing, characterized in that, It includes a main structure, strain fiber (4), temperature fiber (10), stress fiber (11) and fiber demodulator. The main structure includes a compression rod (2), a sensing column (3), an upper protective cover (1) and a lower protective cover (9). The compression rod (2) is a solid round rod with an optical fiber groove (8) on its wall along the axial direction, and external threads A (7) are opened on the head and tail of the compression rod (2). The sensing column (3) is a hollow cylinder, and its hollow part is a through hole (12) along the axial direction. The diameter of the through hole (12) is matched with the diameter of the compression rod (2). An external thread B (14) is opened on the outer wall of the tail of the sensing column (3). Both the upper protective cover (1) and the lower protective cover (9) are semi-hollow cylindrical. The inner diameter of the hollow part is adapted to the outer diameter of the sensing column (3), and an internal thread hole (5) adapted to the external thread A (7) is opened at the center of the inner bottom surface. The hollow part of the upper protective cover (1) has a lead hole (6) that penetrates the inner and outer walls, and the inner wall of the hollow part of the lower protective cover (9) has an internal thread (15) adapted to the external thread B (14). The compression rod (2) is fitted into the sensing column (3) through the through hole (12), and its tail is locked in the internal thread hole (5) of the lower protective cover (9) through the external thread A (7). The tail of the sensing column (3) is screwed into the internal thread (15) through the external thread B (14) and the internal thread (15) so that the sensing column (3) is completely seated in the lower protective cover (9). The head of the compression rod (2) is screwed into the internal thread hole (5) of the upper protective cover (1) through the external thread A (7), so that the upper protective cover (1) is installed on the upper part of the sensing column (3), and a gap H is left between the upper end face of the sensing column (3) and the inner bottom face of the upper protective cover (1). One end of the strain fiber (4) is connected to the fiber demodulator, and the other end enters the upper protective cover (1) through the lead hole (6) of the upper protective cover (1), extends downward along the through hole (12), and is pasted in the fiber groove (8) until the tail end of the fiber groove (8). The temperature fiber (10) and stress fiber (11) maintain a constant distance L between them. One end of each fiber is connected to the fiber demodulator, and the other end is wound evenly from top to bottom around the sensing column (3) in a spiral manner. The gap H is greater than 2cm, and the gap H is adjusted by screwing the external thread A (7) of the head of the compression rod (2) to the internal thread hole (5) of the upper protective cover (1); After the main structure and the three types of optical fibers are installed, a plastic protective sleeve (13) is put on the multi-parameter optical fiber sensor. The constant spacing L is 0.8-2cm.

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