Multi-parameter optical fiber sensor for stratum sensing

Abstract

The invention 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 in the axis direction, one end of the strain optical fiber is connected with the optical fiber demodulator, and the other end of the strain optical fiber extends downwards along the through hole of the sensing column and is pasted in the optical fiber groove. And the temperature optical fiber and the stress optical fiber keep a constant distance L and are uniformly wound on the column body of the sensing column from top to bottom in a spiral manner. Different stratum parameters can be collected by installing different sensing optical fibers, multi-parameter measurement of the stratum is achieved, the sensor only needs to be placed in a soil body to be measured, stratum information of the area can be converted through wavelength changes measured by the optical fiber demodulator connected with the optical fibers, the device can be repeatedly used, operation is easy, and cost is low.

Description

Technical Field

[0001] The present invention relates to the field of measuring equipment, and in particular to a multi-parameter optical fiber sensor for formation sensing. Background Art

[0002] The perception of stratum parameters is an indispensable part of geological construction projects. The temperature, confining pressure and vertical strain of buildings in deep underground soil are crucial to the operation of buildings and directly affect the safety of building operations. Therefore, it is of great significance to accurately measure the temperature, confining pressure and vertical strain of deep soil, and there are currently some sensing devices.

[0003] For example, Chinese patent document CN118777368A discloses a DTS-based in-situ distributed measurement system and method for soil heat flux, which uses DTS measuring tubes to collect and calculate the temperature, thermal conductivity and moisture content distribution of the 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 damage perception and disaster warning intelligent geotextile based on deep learning. The deep learning module chipset collects soil stress, strain, temperature, moisture content and other data. However, the geotextile is only suitable for shallow roadbeds and other locations, and its application range is limited.

[0006] Chinese patent document CN117759229A discloses a dynamic monitoring and sensing system and method for the temperature field of deep strata in metal mines. Temperature is collected by setting temperature probes in each temperature monitoring borehole in the target tunnel, but the probe can only collect temperature data.

[0007] Chinese patent document CN110567519B discloses a measuring unit for monitoring the pressure and water content of deep hole soil in landslide body, but the unit cannot measure temperature and strain.

[0008] Chinese patent document CN116242986A discloses a soil mechanics test rod and a system and method for measuring the physical and mechanical state of regional surface soil, which is used to measure parameters such as shear strength, stress state, and pore water pressure of soil within a certain area. The device needs to install multiple sensors of various types, has a complex structure, is difficult to operate, and has a high monitoring cost.

[0009] In summary, existing monitoring equipment has problems such as incomplete monitoring parameters, high cost, and cumbersome operation. Based on this, the present invention designs a multi-parameter optical fiber sensor for formation perception. Summary of the invention

[0010] The technical problem to be solved by the present invention is the defects of the prior art, and the purpose is to achieve accurate perception of multiple parameters of the formation in view of the defects of the prior art.

[0011] In order to achieve the above-mentioned purpose, the present invention intends to adopt the following technical scheme.

[0012] A multi-parameter optical fiber sensor for formation sensing, comprising a main structure, a strain optical fiber, a temperature optical fiber, a stress optical fiber and an optical fiber demodulator, wherein the main structure comprises a compression rod, a sensing column, an upper protective cover and a lower protective cover;

[0013] The compression rod is a solid round rod, a fiber optic groove is formed on the rod wall along the axial direction, and external threads A are formed on the rod head and the rod 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 rod diameter of the compression rod; an external thread B is provided on the outer wall of the tail of the sensing column;

[0015] The upper protective cover and the lower protective cover are both semi-hollow cylindrical, the inner diameter of the hollow part thereof is adapted to the outer diameter of the sensing column, and an internal thread hole adapted to the external thread A is opened at the center of the inner bottom surface; a lead hole penetrating the inner and outer walls is opened in the hollow part of the upper protective cover, and an internal thread adapted to the external thread B is opened on the inner wall of the hollow part of the lower protective cover;

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

[0017] One end of the strain 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 tail end of the optical fiber groove;

[0018] A constant distance L is maintained between the temperature optical fiber and the stress optical fiber, one end of each is connected to the optical fiber demodulator, and the other end is evenly wound on the column body of the sensing column from top to bottom in a spiral manner.

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

[0020] Preferably, after the main structure and the three optical fibers are installed, a plastic protective cover is put on the outer cover of the multi-parameter optical fiber sensor.

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

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention designs a multi-parameter optical fiber sensor for formation sensing, which measures formation parameters through optical fiber with high measurement accuracy.

[0024] (2) The present invention realizes multi-parameter measurement of formations 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, and the wavelength change measured by the optical fiber demodulator connected to the sensing optical fiber can be used to convert the stratigraphic information of the area. The device is reusable, simple to operate, and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of a multi-parameter optical fiber sensor in an embodiment of the present invention.

[0027] Figure 2 Schematic diagram of the upper protective cover structure in an embodiment of the present invention.

[0028] Figure 3 Schematic diagram of the lower protective cover structure in an embodiment of the present invention.

[0029] Figure 4 Schematic diagram of the compression rod structure in an embodiment of the present invention.

[0030] Figure 5 Schematic diagram of the sensing column structure in an embodiment of the present invention.

[0031] Figure numerals: 1. upper protective cover; 2. compression rod; 3. sensing column; 4. strain optical fiber; 5. internal thread hole; 6. lead hole; 7. external thread A; 8. optical fiber groove; 9. lower protective cover; 10. temperature optical fiber; 11. stress optical fiber; 12. through hole; 13. plastic protective cover; 14. external thread B; 15. internal thread. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

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

[0034] As can be seen from the above drawings, the present invention provides a multi-parameter optical fiber sensor for formation sensing, including a main structure, strain optical fiber 4, temperature optical fiber 10, stress optical fiber 11 and an optical fiber demodulator, wherein 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, a fiber optic groove 8 is formed on the rod wall along the axial direction, and external threads A7 are formed on the rod head and the rod tail of the compression rod 2.

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

[0037] The upper protective cover 1 and the lower protective cover 9 are both semi-hollow cylindrical, the inner diameter of the hollow part is compatible with the outer diameter of the sensing column 3, and an internal thread hole 5 compatible with the external thread A7 is opened at the center position of the inner bottom surface; the hollow part of the upper protective cover 1 is opened with a lead hole 6 penetrating the inner and outer walls, and the inner wall of the hollow part of the lower protective cover 9 is opened with an internal thread 15 compatible with the external thread B14.

[0038] The compression rod 2 is inserted 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, and the tail of the sensing column 3 is screwed with the external thread B14 and the internal thread 15 so that the sensing column 3 is completely located in the lower protective cover 9; the head of the compression rod 2 is screwed with the internal thread hole 5 of the upper protective cover 1 through the external thread A7, and 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 surface of the sensing column 3 and the inner bottom surface of the upper protective cover 1.

[0039] In this embodiment, the gap H is greater than 2 cm, and the gap H is adjusted by screwing the external thread A7 on the head of the compression rod 2 with 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 holes 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, so that the gap H can be adjusted by screwing the external thread A7 on the head of the compression rod 2 with the internal threaded hole 5 of the upper protective cover 1.

[0041] One end of the strain optical fiber 4 is connected to the optical 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 optical fiber groove 8 until the tail end of the optical fiber groove 8.

[0042] In actual operation, the optical fiber 4 is first pasted into the optical fiber groove 8 of the compression rod 2, and then the compression rod 2 is installed in the sensing column 3. 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 upper protective cover 1 is installed, and the optical fiber is led out through the lead-in hole 6.

[0043] The temperature optical fiber 10 and the stress optical fiber 11 maintain a constant distance L between them, one end of each is connected to the optical fiber demodulator, and the other end is evenly wound on the column body of the sensing column 3 from top to bottom in a spiral manner.

[0044] In this embodiment, the constant distance L is 0.8 cm-2 cm. Specifically, L=1 cm is selected.

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

Claims

1. A multi-parameter optical fiber sensor for formation sensing, characterized in that: It comprises a main structure, a strain optical fiber (4), a temperature optical fiber (10), a stress optical fiber (11) and an optical fiber demodulator, wherein the main structure comprises 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, a fiber optic groove (8) is formed on the rod wall along the axial direction, and external threads A (7) are formed on the rod head and the rod tail of the compression rod (2); The sensing column (3) is a hollow cylinder, the hollow part of which is a through hole (12) along the axial direction, and the diameter of the through hole (12) is adapted to the rod diameter of the compression rod (2); an external thread B (14) is formed on the outer wall of the tail of the sensing column (3); The upper protective cover (1) and the lower protective cover (9) are both semi-hollow cylindrical, the inner diameter of the hollow part thereof is matched with the outer diameter of the sensing column (3), and an internal thread hole (5) matched with the external thread A (7) is opened at the center position of the inner bottom surface; the hollow part of the upper protective cover (1) is opened with a lead hole (6) penetrating the inner and outer walls, and the inner wall of the hollow part of the lower protective cover (9) is opened with an internal thread (15) matched with the external thread B (14); The compression rod (2) is inserted 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), and the tail of the sensing column (3) is screwed together with 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 together with the internal thread hole (5) of the upper protective cover (1) through the external thread A (7), and 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 surface of the sensing column (3) and the inner bottom surface of the upper protective cover (1); One end of the strain optical fiber (4) is connected to the optical 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 adhered in the optical fiber groove (8) until the tail end of the optical fiber groove (8); A constant distance L is maintained between the temperature optical fiber (10) and the stress optical fiber (11), one end of each of which is connected to an optical fiber demodulator, and the other end of each of which is evenly wound around the body of the sensing column (3) from top to bottom in a spiral manner.

2. A multi-parameter optical fiber sensor for formation sensing according to claim 1, characterized in that: The gap H is greater than 2 cm, and the gap H is adjusted by screwing the external thread A (7) on the head of the compression rod (2) and the internal thread hole (5) of the upper protective cover (1).

3. The multi-parameter optical fiber sensor for formation sensing according to claim 1, characterized in that: After the main structure is installed and the three optical fibers are installed, a plastic protective cover (13) is put on the outer cover of the multi-parameter optical fiber sensor.

4. The multi-parameter optical fiber sensor for formation sensing according to claim 1, characterized in that: The constant distance L is 0.8-2 cm.

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