A high-precision continuous monitoring optical cable for rock temperature and water content and a method of using the same

Abstract

The present invention discloses a high-precision integrated continuous monitoring optical cable for rock mass temperature and water content and a method for using the same. The optical cable comprises an outer sheath, a steel strand is arranged inside the outer sheath, an armor tube is arranged inside the steel strand, a plurality of adhesive terminals are arranged inside the armor tube, and an optical fiber and a heating wire are arranged on the adhesive terminal. The present invention adheres the optical fiber to the adhesive terminal, utilizes the property of the adhesive terminal being stretched or compressed with the change of temperature, and realizes temperature monitoring through optical fiber deformation. When water content monitoring is required, it is only necessary to connect the wire to a power source to heat the heating wire. Different water contents of rock mass soil will cause different temperatures of the adhesive terminal, and the moisture content is monitored through optical fiber deformation. High-precision continuous dual-parameter monitoring of temperature and moisture content can be realized through one optical cable. A closed space is formed by the outer sheath, which overcomes the problems of condensation and electromagnetic interference inside the optical cable in humid air, greatly prolongs the service life of the optical cable, and improves the reliability of the optical cable.

Description

Technical Field

[0001] The invention belongs to the technical field of optical cable monitoring, and in particular relates to an optical cable for continuous monitoring of rock temperature and water content with high precision and a use method thereof. Background Art

[0002] Optical cable monitoring technology is an emerging technology that uses optical fiber sensors to continuously monitor rock temperature and moisture content at multiple points. The development of this technology can be traced back to the 1980s, when optical fiber sensor technology was first used in the field of structural health monitoring. Subsequently, optical fiber sensor technology has been widely used in civil engineering, geological exploration and other fields.

[0003] In recent years, with the continuous progress of optical fiber manufacturing technology and optical measurement technology, optical cable monitoring technology has shown great application potential in rock temperature and moisture content monitoring. Although the existing traditional optical fiber distributed temperature monitoring technology can achieve continuous monitoring, it uses the temperature sensitivity of the optical fiber itself for temperature monitoring, resulting in low test accuracy. Although the temperature sensors based on fiber Bragg gratings have high accuracy, they are all point monitoring and cannot continuously monitor the rock temperature.

[0004] The Chinese invention patent publication number is CN 118348062 A, which discloses a soil moisture content measurement method and device based on FBG thermal pulse dual probes. Through the dual probe method, one probe is heated and the other probe is monitored, thereby realizing the monitoring of different moisture contents. However, this method can only realize single-point or limited multi-point monitoring. At the same time, the patent uses bare fiber to be directly encapsulated in the probe, and realizes temperature and moisture content monitoring through the sensitivity of the optical fiber itself to temperature. The accuracy is low and high-precision continuous monitoring cannot be performed. The Chinese invention patent publication number is CN 103454309 A, which discloses a soil moisture content distributed measurement method and system. Through carbon fiber heating, DTS equipment is used to collect optical fiber data, and then the temperature is recognized through the sensitivity of the optical fiber itself to temperature, and then the different moisture contents in the soil can be measured. However, this method uses the sensitivity of the optical fiber itself to temperature to realize temperature and moisture content monitoring, and the accuracy is low, with only a change of 10pm per degree Celsius, and high-precision monitoring cannot be performed. China Invention Patent Publication No. CN 106979791 A discloses a method for heating an FBG sensor in a package. The patent adopts a dual probe form, using two corundum tubes to place the heating wire and the optical fiber inside. When in use, the dual probes are inserted into the body to be measured, the heating wire is powered on for heating, and the optical fiber monitors its temperature. The temperature is different under different moisture contents, thereby realizing monitoring of different moisture contents. However, this method also realizes temperature and moisture content monitoring through the optical fiber's own sensitivity to temperature, and has low accuracy. At the same time, because it uses a corundum tube, multi-point continuous monitoring cannot be realized, so high-precision continuous monitoring cannot be performed. Summary of the invention

[0005] In order to solve the technical problems existing in the prior art, the purpose of the present invention is to provide a high-precision integrated continuous monitoring optical cable for rock temperature and water content and a method of use, which can realize dual-parameter monitoring of temperature and water content through one optical cable.

[0006] In order to achieve the above purpose and the above technical effect, the technical solution adopted by the present invention is:

[0007] A high-precision integrated continuous monitoring optical cable for rock temperature and water content comprises an outer sheath, a steel strand is arranged inside the outer sheath, an armor tube is arranged inside the steel strand, a plurality of adhesive terminals are arranged inside the armor tube, and optical fibers and heating wires are arranged on the adhesive terminals.

[0008] Furthermore, a plurality of linearly arranged pasting terminals are provided inside the armored tube, and a V-shaped groove is provided above the pasting terminal for pasting the optical fiber.

[0009] Furthermore, a wire fixing hole for fixing the heating wire wire and a heating wire installation hole for installing the heating wire are provided below the adhesive terminal, and the wire is connected to the heating wire and provides electrical energy to the heating wire.

[0010] Furthermore, the wire passes through the wire fixing hole and is fixed together with the adhesive terminal through the heat-resistant insulating glue, so that it serves as a reinforcing connector to connect all the adhesive terminals together, thereby preventing the optical fiber and the heating wire from being affected by external forces and ensuring the test effect.

[0011] Furthermore, the adhesive terminal is made of copper rod.

[0012] The present invention also discloses a method for using an optical cable for continuously monitoring rock temperature and water content with high precision, comprising the following steps:

[0013] (1) Use copper rods to make adhesive terminals, select the number of adhesive terminals according to the required distance, then place the adhesive terminals on the table in sequence, and then place the entire optical fiber into the V-groove of the placed adhesive terminals;

[0014] (2) Hang a mass block at the end of the optical fiber to ensure that the force is evenly distributed along the entire optical fiber.

[0015] (3) After completing the above steps, use glue to glue the optical fiber into the V-groove corresponding to each adhesive terminal in turn;

[0016] (4) Place the bonded optical fiber in an oven in a free state to bake to ensure that the glue is completely solidified;

[0017] (5) After baking, take out the optical fiber and the adhesive terminal, and pass the heating wire through the heating wire installation hole corresponding to each adhesive terminal in turn. During the placement process, ensure that the heating wire is in a straight state without bending, so that the adhesive terminal is evenly stressed during heating;

[0018] (6) Use wires to weld the heating wires in series. After the series connection is completed, pass the wires of the loop through the wire fixing holes. Use insulating glue to fix the wires to the adhesive terminals each time they pass through a wire fixing hole.

[0019] (7) The inner core obtained in step (6) is used as the core of the optical cable, and is successively placed on a tube making machine, a cabling machine, and a coating machine to make armored tubes, steel strands, and outer sheaths, and finally forms the required rock mass temperature and water content high-precision integrated continuous monitoring optical cable;

[0020] (8) The adhesive terminal made of copper rod will stretch or compress with the change of temperature, causing the optical fiber pasted on it to deform, thereby monitoring the temperature; when moisture content monitoring is required, it is only necessary to connect the wire to the power supply to make the heating wire heat up. The different moisture content of the rock soil will cause the temperature of the adhesive terminal to be different, causing the optical fiber to deform, thereby monitoring the moisture content in the rock soil.

[0021] Furthermore, the temperature calculation formula is:

[0022] After the heating wire is powered on for a period of time, the temperature tends to be stable. Select a characteristic time interval , the arithmetic average of the multiple temperature values ​​measured in the time interval is obtained , minus the initial temperature , that is, the temperature characteristic value is obtained ;

[0023] The higher the water content of the rock, the better its thermal conductivity. After heating, the greater the degree of heat diffusion and the greater the amount of diffusion, the lower the temperature that can be raised and the smaller the temperature characteristic value.

[0024] Furthermore, the calculation formula for the water content in rock mass soil is:

[0025]

[0026] In the formula, θ is the volumetric moisture content of the soil to be tested; is the temperature characteristic value; is the dry thermal conductivity of soil; Q is the heating power per unit length; K is the thermal diffusivity of the soil; t is the heating time; is the outer diameter of the optical cable; is Euler's constant, is the dry density; are empirical parameters of the CK model, which are related to soil type and freezing state; is the saturated thermal conductivity; is the porosity of the soil; is the density of water.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) The present invention pastes the optical fiber on the paste terminal, and uses the characteristics of the paste terminal made of copper rods that will stretch or compress with the change of temperature. The temperature is monitored by the deformation of the optical fiber. The use of copper rods as carriers can greatly improve the detection accuracy, which can reach 30pm / nm. When it is necessary to monitor the moisture content, it is only necessary to connect the wire to the power supply to heat the heating wire. The different moisture contents of the rock mass soil will cause different temperatures of the paste terminal, causing the optical fiber to deform, thereby monitoring the moisture content in the rock mass soil.

[0029] 2) The present invention can determine the parameters monitored by the optical cable according to whether power is on or not, and can realize dual parameter monitoring of temperature and moisture content through one optical cable.

[0030] 3) The present invention can realize high-precision continuous dual-parameter monitoring of temperature and moisture content, and forms a closed space through the outer sheath, which overcomes the problems of condensation and electromagnetic interference inside the optical cable in humid air, greatly prolongs the service life of the optical cable, and improves the reliability of the optical cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2 It is a structural schematic diagram of the adhesive terminal of the present invention;

[0033] Figure 3 It is a layout diagram of the adhesive terminal, optical fiber, wire and heating wire of the present invention;

[0034] Among them: 1. Outer sheath; 2. Steel strand; 3. Armored tube; 4. Optical fiber; 5. Adhesive terminal; 6. Wire; 7. Heating wire; 8: Heat-resistant insulating glue; 51. V-shaped groove; 52. Wire fixing hole; 53. Heating wire installation hole. DETAILED DESCRIPTION

[0035] The present invention is described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0036] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0037] like Figure 1-3 As shown, a high-precision integrated continuous monitoring optical cable for rock temperature and water content comprises an outer sheath 1, a steel strand 2 is arranged inside the outer sheath 1 for enhancing the strength of the optical cable, an armor tube 3 is arranged inside the steel strand 2 for protecting the internal structure, a plurality of linearly arranged adhesive terminals 5 are arranged inside the armor tube 3, a V-shaped groove 51 is provided above the adhesive terminal 5 for adhesive optical fiber 4, and a wire fixing hole 52 for fixing the heating wire wire 6 and a heating wire installation hole 53 for installing the heating wire 7 are provided below the adhesive terminal 5.

[0038] The adhesive terminal 5 is made of a copper rod, which has a large thermal expansion coefficient and can increase the accuracy of temperature monitoring.

[0039] The wire 6 passes through the wire fixing hole 52 of the adhesive terminal 5 and is fixed to the adhesive terminal 5 by the heat-resistant insulating glue 8, so that the wire 6 can not only provide electrical energy for the heating wire 7, but also serve as a reinforcing connector to connect all adhesive terminals 5, thereby avoiding stress on the optical fiber and the heating wire and ensuring the test results.

[0040] By placing the heating wire 7 in the heating wire installation hole 53 of the pasting terminal 5, the temperature can be provided for the pasting terminal 5, and then the soil moisture content can be measured.

[0041] A method for using an optical cable for high-precision continuous monitoring of rock temperature and water content, comprising the following steps:

[0042] (1) Place the adhesive terminals 5 on the table in sequence according to the required distance, and then place the entire optical fiber 4 into the V-groove 51 of the adhesive terminal 5;

[0043] (2) Hang a mass block at the end of the optical fiber 4 to ensure that the force on the entire optical fiber 4 is uniform;

[0044] (3) After completing the above steps, use glue to sequentially glue all the optical fibers 4 corresponding to the pasting terminals 5 into the V-grooves 51 starting from the head end of the optical fibers 4;

[0045] (4) After the glue is applied, place the glued optical fiber 4 freely on the baking tray. Make sure that the optical fiber 4 is in a free state and cannot be subjected to force. Place the baking tray in the oven for baking to ensure that the glue is completely solidified.

[0046] (5) After baking, take out the optical fiber 4 and the pasting terminal 5, and place the heating wire 7 in the heating wire installation hole 53 of the pasting terminal 5 in sequence. During the placement process, ensure that the heating wire 7 is in a straight state without bending, so as to ensure that the pasting terminal 5 is evenly stressed during heating;

[0047] (6) Use the wire 6 to weld the heating wire 7 in series. After the series connection is completed, pass the wire 6 of the loop through the wire fixing hole 52. After each wire fixing hole 52 is passed through, use the heat-resistant insulating glue 8 to fix the wire 6 to the adhesive terminal 5;

[0048] (7) After completing the above steps, the finished inner core is directly used as the fiber core of the optical cable, and is placed in the tube making machine, the cabling machine and the coating machine to make the armor tube 3, the steel strand 2 and the outer sheath 1, and finally form a complete optical cable;

[0049] The adhesive terminal 5 made of copper rod will stretch or compress with the change of temperature, causing the optical fiber 4 pasted thereon to deform, thereby monitoring the external temperature change. Since the adhesive terminal 5 is made of copper rod, the thermal expansion coefficient of the copper rod is much higher than that of the bare fiber, so the temperature can be monitored with high precision; and the copper rod is linearly distributed along the optical fiber 4 and packaged into an optical cable, which can realize continuous monitoring of temperature and moisture content; when moisture content monitoring is required, it is only necessary to connect the wire 6 to the power supply to make the heating wire 7 heat up. Different moisture contents of the soil will cause different temperatures of the adhesive terminal 5, so the moisture content in the soil is detected. The calculation formula and test principle of the moisture content are as follows:

[0050] The thermal conductivity of soil changes with its moisture content. The higher the moisture content, the stronger its thermal conductivity. The optical cable with self-heating function is implanted into the soil, and the heating power is fixed to establish the relationship between the degree of heat diffusion and the moisture content in the soil, thereby achieving qualitative and quantitative monitoring of the moisture content of the surrounding soil. The degree of heat diffusion is expressed by the temperature characteristic value, which is defined as: after a period of power heating, the measured temperature tends to be stable, and a certain characteristic time interval is selected , the arithmetic average of the multiple temperature values ​​measured in the time interval is obtained , minus the initial temperature , that is, the temperature characteristic value is obtained The higher the moisture content of the soil, the better its thermal conductivity. After being heated by an external heat source, the greater the degree of heat diffusion and the greater the amount of heat diffusion, the lower the temperature that can be raised and the smaller the temperature characteristic value.

[0051] Volumetric moisture content and temperature characteristic values The relationship expression is:

[0052]

[0053] In the formula, θ is the volumetric moisture content of the soil to be tested; is the temperature characteristic value; is the dry thermal conductivity of soil, Wm -1 K -1 ; Q is the heating power per unit length, Wm -1 ; K is the thermal diffusion coefficient of the soil, m 2 s -1 ; t is the heating time, s; is the outer diameter of the optical cable, and is Euler's constant; is the dry density, g / cm 3 ; are empirical parameters of the CK model, which are related to soil type and freezing state; is the saturated thermal conductivity, Wm -1 K -1 ; is the porosity of the soil; is the density of water, g / cm 3 .

[0054] Parts or structures not specifically described in the present invention may adopt existing technologies or existing products and will not be described in detail here.

[0055] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for using an optical cable for high-precision continuous monitoring of rock temperature and water content, characterized in that: The rock mass temperature and water content high-precision integrated continuous monitoring optical cable comprises an outer sheath, a steel strand is arranged inside the outer sheath, an armor tube is arranged inside the steel strand, a plurality of adhesive terminals are arranged inside the armor tube, an optical fiber and a heating wire are arranged on the adhesive terminals, and the adhesive terminals are made of copper rods; The method of use comprises the following steps: (1) Use copper rods to make adhesive terminals, select the number of adhesive terminals according to the required distance, then place the adhesive terminals on the table in sequence, and then place the entire optical fiber into the V-groove of the placed adhesive terminals; (2) Hang a mass block at the end of the optical fiber to ensure that the force is evenly distributed along the entire optical fiber. (3) After completing the above steps, use glue to glue the optical fiber into the V-groove corresponding to each adhesive terminal in turn; (4) Place the bonded optical fiber in an oven in a free state to bake to ensure that the glue is completely solidified; (5) After baking, take out the optical fiber and the adhesive terminal, and pass the heating wire through the heating wire installation hole corresponding to each adhesive terminal in turn. During the placement process, ensure that the heating wire is in a straight state without bending, so that the adhesive terminal is evenly stressed during heating; (6) Use wires to weld the heating wires in series. After the series connection is completed, pass the wires of the loop through the wire fixing holes. Use insulating glue to fix the wires to the adhesive terminals each time they pass through a wire fixing hole. (7) The inner core obtained in step (6) is used as the core of the optical cable, and is successively placed on a tube making machine, a cabling machine, and a coating machine to make armored tubes, steel strands, and outer sheaths, and finally forms the required rock mass temperature and water content high-precision integrated continuous monitoring optical cable; (8) The adhesive terminal made of copper rod will stretch or compress with the change of temperature, causing the optical fiber pasted on it to deform, thereby monitoring the temperature; when moisture content monitoring is required, it is only necessary to connect the wire to the power supply to make the heating wire heat up. The different moisture content of the rock soil will cause the temperature of the adhesive terminal to be different, causing the optical fiber to deform, thereby monitoring the moisture content in the rock soil.

2. The method for using a high-precision continuous monitoring optical cable for rock temperature and water content according to claim 1 is characterized in that: A plurality of linearly arranged pasting terminals are arranged inside the armored tube, and a V-shaped groove is provided above the pasting terminal for pasting optical fibers.

3. The method for using a high-precision and continuous monitoring optical cable for rock temperature and water content according to claim 1 is characterized in that: A wire fixing hole for fixing the heating wire and a heating wire installation hole for installing the heating wire are provided below the adhesive terminal. The wire is connected to the heating wire and provides electrical energy to the heating wire.

4. The method for using a high-precision continuous monitoring optical cable for rock temperature and water content according to claim 3 is characterized in that: The wire passes through the wire fixing hole and is fixed together with the adhesive terminal through the heat-resistant insulating glue, which serves as a reinforcing connector to connect all the adhesive terminals together, thereby preventing the optical fiber and the heating wire from being affected by external forces and ensuring the test effect.

5. The method for using a high-precision and continuous monitoring optical cable for rock temperature and water content according to claim 1 is characterized in that: The temperature is calculated as: After the heating wire is powered on for a period of time, the temperature tends to be stable. Select a characteristic time interval [ , ], the arithmetic average of the multiple temperature values ​​measured in the time interval is obtained , minus the initial temperature , that is, the temperature characteristic value is obtained , = - ; The higher the water content of the rock, the better its thermal conductivity. After heating, the greater the degree of heat diffusion and the greater the amount of diffusion, the lower the temperature that can be raised and the smaller the temperature characteristic value.

6. The method for using a high-precision and continuous monitoring optical cable for rock temperature and water content according to claim 1 is characterized in that: The calculation formula for the water content in rock mass soil is: ； In the formula, θ is the volumetric moisture content of the soil to be tested; is the temperature characteristic value; is the dry thermal conductivity of soil; Q is the heating power per unit length; K is the thermal diffusion coefficient of the soil; t is the heating time; is the outer diameter of the optical cable; , is Euler's constant, =0.5772; is the dry density; are empirical parameters of the CK model, which are related to soil type and freezing state; is the saturated thermal conductivity; is the porosity of the soil; is the density of water.

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