阅读说明：本技术 基于分布式光纤的土工膜破损渗漏量监测系统及监测方法 (Geomembrane damage leakage amount monitoring system and method based on distributed optical fibers ) 是由 程琳 宋福彬 杨杰 李炎隆 王赵汉 于 2019-09-29 设计创作，主要内容包括：本发明公开了一种基于分布式光纤的土工膜破损渗漏量监测系统,包括渗流系统、加热系统和DTS系统,渗流系统包括模型槽和供水系统,模型槽内设置有土石坝断面模型和土工膜,供水系统为土石坝端面模型提供渗流,加热系统为土石坝端面模型提供热源；DTS系统包括依次相连的光纤、DTS解调设备和采集分析光纤温度及相应位置信息的工控机,光纤的一部分设置在土工膜上,其余部分设置在土石坝断面模型内部。本发明还公开了基于分布式光纤的土工膜破损渗漏量监测方法,该方法监测的数据连续性强,能反映出大坝整体的渗流情况,根据光纤的温度变化规律可推测出土工膜的破损位置和渗流量,可用于实际工程中。(The invention discloses a geomembrane damage leakage monitoring system based on distributed optical fibers, which comprises a seepage system, a heating system and a DTS system, wherein the seepage system comprises a model groove and a water supply system, an earth and rockfill dam section model and a geomembrane are arranged in the model groove, the water supply system provides seepage for the earth and rockfill dam end face model, and the heating system provides a heat source for the earth and rockfill dam end face model; the DTS system comprises optical fibers, DTS demodulation equipment and an industrial personal computer for collecting and analyzing the temperature of the optical fibers and corresponding position information, wherein the optical fibers are sequentially connected, one part of the optical fibers is arranged on the geomembrane, and the other part of the optical fibers is arranged inside the cross section model of the earth-rock dam. The invention also discloses a geomembrane damage leakage monitoring method based on the distributed optical fibers, the data monitored by the method has strong continuity, the integral seepage condition of the dam can be reflected, the damage position and the seepage quantity of the geomembrane can be estimated according to the temperature change rule of the optical fibers, and the method can be used in actual engineering.)

1. A geomembrane damage leakage monitoring system based on a distributed optical fiber is characterized by comprising a seepage system, a heating system and a DTS system, wherein the seepage system comprises a model groove (14) and a water supply system, an earth and rockfill dam section model (13) and a geomembrane (5) are arranged in the model groove (14), the water supply system provides seepage for the earth and rockfill dam end face model (13), and the heating system provides a heat source for the earth and rockfill dam end face model (13); the DTS system comprises an optical fiber (6), a DTS demodulation device (9) and an industrial personal computer (10) which collects and analyzes the temperature of the optical fiber (6) and corresponding position information, wherein the optical fiber (6), the DTS demodulation device and the industrial personal computer are sequentially connected, one part of the optical fiber (6) is arranged on the geomembrane (5), and the other part of the optical fiber is arranged inside the earth and rockfill dam section model (13).

2. The geomembrane damage leakage monitoring system based on the distributed optical fiber according to claim 1, wherein the heating system comprises a silicon rubber heating belt (8), the silicon rubber heating belt (8) is connected with a thermostat (11), and the thermostat (11) is connected with an alternating current power supply (12).

3. The geomembrane damage and leakage monitoring system based on the distributed optical fiber as claimed in claim 2, wherein the earth and rockfill dam end face model (13) is formed by stacking sand particles, the silicon rubber heating belt (8) is wound on a plastic rod (17), and the plastic rod (17) is buried in the middle of the earth and rockfill dam end face model (13).

4. The geomembrane damage leakage monitoring system based on the distributed optical fiber as claimed in claim 1, wherein the water supply system comprises a water inlet pipe (1) and a water gate (3), the water gate (3) divides the bottom of the model groove (14) into a left part and a right part, the water inlet pipe (1) is arranged at the top of the left side of the model groove (14), the earth and rockfill dam section model (13) is arranged at the right side of the model groove (14), a water baffle (2) is arranged between the water gate (3) and the earth and rockfill dam section model (13), the water baffle (2) is fixed at the top of the inner wall of the model groove (14), and a gap is reserved between the bottom of the water baffle (2) and the bottom of the model groove (14).

5. The geomembrane damage leakage monitoring system based on the distributed optical fiber as claimed in claim 4, wherein the bottom of one side of the mold groove (14) close to the water inlet pipe (1) is provided with a water outlet a (4), the bottom of the other opposite side is provided with a water outlet b (7), and water valves are respectively installed on the water outlet a (4) and the water outlet b (7).

6. The geomembrane damage leakage monitoring system based on the distributed optical fibers as claimed in claim 1, wherein the geomembrane (5) is wrapped outside the earth and rockfill dam section model (13), a part of the optical fibers (6) are arranged on one side of the geomembrane (5) close to the upstream in an S shape, and the rest part of the optical fibers are arranged inside the earth and rockfill dam section model (13) layer by layer.

7. The geomembrane damage leakage monitoring system based on the distributed optical fiber according to claim 1, wherein the optical fiber (6) is a linear multimode temperature-sensing optical fiber, the DTS demodulation device (9) demodulates and records a temperature value of the optical fiber (6) in a natural cooling process, and the DTS demodulation device (9) performs distributed temperature measurement based on a raman optical time-domain emission measurement technology.

8. The method is characterized by comprising the steps of arranging optical fibers (6) on the surface of a geomembrane (5) and inside an earth and rockfill dam section model (13), heating the earth and rockfill dam section model (13) by adopting a silicon rubber heating belt (8), collecting temperature change of the optical fibers (6) in a natural cooling process through a DTS demodulation device (9) and an industrial personal computer (10), and determining the damage position and the leakage amount of the geomembrane (5) through the temperature change rule of the optical fibers (6).

9. The geomembrane damage leakage monitoring method based on the distributed optical fiber according to claim 8, characterized by comprising the following steps:

step 1: arranging optical fibers (6) on the surface of the geomembrane (5) and inside the earth and rockfill dam section model (13), wherein the optical fibers (6) on the bottom layer are close to the bottom of the earth and rockfill dam section model (13), and the optical fibers (6) on the top layer are close to the top of the earth and rockfill dam section model (13); the optical fiber (6) is connected with a DTS demodulation device (9), the DTS demodulation device (9) is connected with an industrial personal computer (10), and the industrial personal computer (10) is connected with a power supply;

step 2: winding a silicon rubber heating belt (8) on a plastic rod (17), connecting the silicon rubber heating belt (8) with a thermostat (11) and an alternating current power supply (12), and embedding the plastic rod (17) in the earth and rockfill dam section model (13);

and step 3: injecting water into the model groove (14), opening a sluice (3) at the upstream of the earth and rockfill dam section model (13), and closing the sluice (3) after the water level of the earth and rockfill dam section model (13) reaches a preset water level;

and 4, step 4: heating the earth and rockfill dam section model (13) by using a silicon rubber heating belt (8), wherein the temperature of the optical fiber (6) rises along with the temperature of the earth and rockfill dam section model (13), and after the optical fiber is heated to a preset temperature, disconnecting an alternating current power supply (12) of the silicon rubber heating belt (8) to naturally cool the optical fiber (6);

and 5: and an industrial personal computer (10) is adopted to record and display the temperature change of the optical fiber (6) in the natural cooling process, and the damage position and the leakage amount of the geomembrane (5) are determined according to the temperature change rule of the optical fiber (6).

10. The geomembrane damage leakage monitoring method based on the distributed optical fiber according to claim 9, wherein the specific process of the step 5 is,

step 5.1: an industrial personal computer (10) is adopted to record and display the temperature change process in the natural cooling process of the optical fiber (6);

step 5.2: recording the optical fiber (6) point with the maximum temperature change amplitude, and inferring the position of the geomembrane (5) corresponding to the optical fiber (6) point, namely the damage position of the geomembrane (5);

step 5.3: recording the temperature T of the optical fiber (6) at the bottom of the earth-rock dam section model (13)_SMeasuring the water flow temperature T around the earth-rock dam section model (13)_fThe leakage quantity Q of the geomembrane (5)_{Convection current}In order to realize the purpose,

in the formula: q_vFor convective heat, Q, between the fibre and the water stream_dThe heat transferred by the water flow due to heat conduction, A_aIs the heat exchange area between the optical fiber and the water flow, i.e. the external surface area of the optical fiber, h is the heat exchange coefficient, T_sIs the temperature, T, of the surface of the optical fiber_fIs the temperature of the water stream, λ_wIs the heat conductivity coefficient of water, and T is the water flow conduction processX is the heat transfer distance of the water.

Technical Field

The invention belongs to the technical field of dam safety monitoring, and relates to a geomembrane damage leakage monitoring system and a geomembrane damage leakage monitoring method based on distributed optical fibers.

Background

The traditional earth-rock material dam impervious body is basically a clay core wall, an inclined core wall, a concrete panel and an asphalt concrete core wall. Compared with the seepage-proofing bodies, the geomembrane has more excellent seepage-proofing performance, and meanwhile, has the advantages of simple and convenient construction, low manufacturing cost, wide application conditions and the like, and is widely applied to seepage-proofing structures of various hydraulic buildings in recent years.

The geomembrane seepage-proofing technology in China starts late, is limited by the early geomembrane production process, durability and construction process, simultaneously considers the defects of holes or defects and cracks of the geomembrane caused by different degrees of splicing seams, connecting seams, hidden damages and the like among the geomembranes, and under the action of a high head, a damaged geomembrane seepage channel generated due to the reasons can generate relatively large seepage amount, so that the safety of the whole dam is threatened. Therefore, the monitoring of the breakage of the reinforced geomembrane becomes an effective way to solve the problem.

At present, the geomembrane breakage monitoring method mainly comprises the following steps: electrical methods, dipole methods, groundwater detection methods, and the like.

The method is suitable for detecting the tiny defects of the geomembrane in a large-area non-welding area, has high detection precision and sensitivity, but has very limited practical application conditions, not only needs to expose all the geomembranes at the detection part, but also has high requirements on the detection environment, and therefore, the method is only suitable for detecting the integrity of the geomembrane in the construction period.

The dipole method is a moving detection on the geomembrane using a pair of fixed-spaced detection electrodes (i.e., dipoles). And recording the potential difference change process, drawing a change curve and detecting the defects. The method has the advantages that the detection sensitivity is high, the millimeter-scale geomembrane defects under the covering layer can be accurately positioned, however, the corresponding detection process is long in time consumption, automatic monitoring cannot be achieved, and time and labor are wasted.

Other detection methods, such as groundwater detection, diffusion tube methods, chemical agent tracing, etc., have certain limitations. For example, the underground water detection method can only judge whether the geomembrane has defects, and cannot determine the specific positions and the number of the defects; although the diffusion hose method can determine the positions and the number of the defects, the actual detection precision is closely related to the number of the arranged hoses; the chemical agent tracing method has the problems of high technical level, high cost and the like, and the detection result has hysteresis and cannot adapt to the actual engineering requirement.

Disclosure of Invention

The invention aims to provide a geomembrane damage leakage monitoring system based on distributed optical fibers, which solves the problems that the existing geomembrane damage monitoring method can only carry out point-mode monitoring, the monitoring data is discontinuous, and the integral seepage condition of a dam cannot be reflected.

The detection accuracy is low, and the detection result has a problem of hysteresis.

The invention further aims to provide a geomembrane damage leakage monitoring method based on the distributed optical fibers.

The invention adopts a first technical scheme that the geomembrane damage leakage monitoring system based on the distributed optical fiber comprises a seepage system, a heating system and a DTS system, wherein the seepage system comprises a model groove and a water supply system, an earth and rockfill dam section model and a geomembrane are arranged in the model groove, the water supply system provides seepage for the earth and rockfill dam end face model, and the heating system provides a heat source for the earth and rockfill dam end face model; the DTS system comprises optical fibers, DTS demodulation equipment and an industrial personal computer for collecting and analyzing the temperature of the optical fibers and corresponding position information, wherein the optical fibers are sequentially connected, one part of the optical fibers is arranged on the geomembrane, and the other part of the optical fibers is arranged inside the cross section model of the earth-rock dam.

The present invention is also technically characterized in that,

the heating system comprises a silicon rubber heating belt, the silicon rubber heating belt is connected with a thermostat, and the thermostat is connected with an alternating current power supply.

The earth and rockfill dam end face model is formed by stacking sand particles, the silicon rubber heating belt is wound on the plastic rod, and the plastic rod is buried in the middle of the earth and rockfill dam end face model.

The water supply system comprises a water inlet pipe and a sluice, the sluice separates the bottom of the model tank into a left part and a right part, the water inlet pipe is arranged at the top of the left side of the model tank, the earth and rockfill dam section model is arranged at the right side of the model tank, a water baffle is arranged between the sluice and the earth and rockfill dam section model and fixed at the top of the inner wall of the model tank, and a gap is reserved between the bottom of the water baffle and the bottom surface of the model tank.

The bottom of one side of the model groove close to the water inlet pipe is provided with a water outlet a, the bottom of the other opposite side is provided with a water outlet b, and water valves are respectively arranged on the water outlet a and the water outlet b.

The geomembrane wraps the outer side of the earth and rockfill dam section model, one part of the optical fibers is distributed on one side, close to the upstream, of the geomembrane in an S shape, and the other parts of the optical fibers are distributed inside the earth and rockfill dam section model in a layered mode.

The optical fiber is a linear multimode temperature sensing optical fiber, the DTS demodulation equipment demodulates and records the temperature value in the natural cooling process of the optical fiber, and the DTS demodulation equipment performs distributed temperature measurement based on a Raman optical time domain emission measurement technology.

The invention adopts a second technical scheme that the geomembrane damage leakage monitoring method based on the distributed optical fibers comprises the steps of arranging the optical fibers on the surface of the geomembrane and in an earth and rockfill dam section model, heating the earth and rockfill dam section model by adopting a silicon rubber heating belt, collecting temperature change in the natural cooling process of the optical fibers through DTS demodulation equipment and an industrial personal computer, and determining the damage position and the leakage of the geomembrane through the temperature change rule of the optical fibers.

The method specifically comprises the following steps:

step 1: arranging optical fibers on the surface of the geomembrane and inside the earth and rockfill dam section model, wherein the optical fibers at the bottom layer are close to the bottom of the earth and rockfill dam section model, and the optical fibers at the top layer are close to the top of the earth and rockfill dam section model; connecting the optical fiber with a DTS demodulation device, wherein the DTS demodulation device is connected with an industrial personal computer which is connected with a power supply;

step 2: winding a silicon rubber heating belt on a plastic rod, wherein the silicon rubber heating belt is connected with a thermostat and an alternating current power supply, and embedding the plastic rod in the earth-rock dam section model;

and step 3: injecting water into the model groove, opening a sluice at the upstream of the earth and rockfill dam section model, and closing the sluice after the water level of the earth and rockfill dam section model reaches a preset water level;

and 4, step 4: heating the earth and rockfill dam section model by using a silicon rubber heating belt, wherein the temperature of the optical fiber rises along with the temperature of the earth and rockfill dam section model, and after the optical fiber is heated to a preset temperature, disconnecting an alternating current power supply of the silicon rubber heating belt to naturally cool the optical fiber;

and 5: and an industrial personal computer is adopted to record and display the temperature change of the optical fibers in the natural cooling process, and the damage position and the leakage amount of the geomembrane are determined according to the temperature change rule of the optical fibers.

The specific process of step 5 is that,

step 5.1: an industrial personal computer is adopted to record and display the temperature change process in the natural cooling process of the optical fiber;

step 5.2: recording the optical fiber point with the maximum temperature change amplitude, and inferring the position of the geomembrane corresponding to the optical fiber point, namely the damaged position of the geomembrane;

step 5.3: recording optical fiber temperature T at bottom of earth-rock dam section model_SMeasuring the temperature T of water around the cross-section model of the earth-rock dam_fLeakage Q of geomembrane_{Convection current}In order to realize the purpose,

in the formula: q_vFor convective heat, Q, between the fibre and the water stream_dThe heat transferred by the water flow due to heat conduction, A_aIs the heat exchange area between the optical fiber and the water flow, i.e. the external surface area of the optical fiber, h is the heat exchange coefficient, T_sIs the temperature, T, of the surface of the optical fiber_fIs the temperature of the water stream, λ_wIs the thermal conductivity of water, T is the instantaneous temperature during conduction of the water flow, and x is the heat transfer distance of the water.

The method has the advantages that the temperature change of all parts of the earth-rock dam section model in the geomembrane is monitored and collected by adopting the distributed optical fibers, the monitored data has strong continuity, and the integral seepage condition of the dam can be reflected; the damage position and the seepage quantity of the geomembrane can be estimated according to the temperature change rule of the optical fibers, the manufacturing cost is low, the accuracy of the detection result is high, the specific position and the number of the defects can be determined in time, and the method can be used in actual engineering.

Drawings

FIG. 1 is a schematic structural diagram of a distributed optical fiber-based homogeneous dam leakage monitoring system according to the present invention;

fig. 2 is a schematic diagram of the arrangement of optical fibers on a geomembrane in the homogeneous earth dam leakage monitoring system based on the distributed optical fibers.

In the figure, 1, a water inlet pipe, 2, a water baffle, 3, a water gate, 4, a water outlet a, 5, a geomembrane, 6, an optical fiber, 7, a water outlet b, 8, a silicon rubber heating belt, 9, a DTS demodulation device, 10, an industrial personal computer, 11, a thermostat, 12, an alternating current power supply, 13, an earth-rock dam section model, 14, a model groove, 15, a geomembrane damaged part, 16, an optical fiber measurement starting point and 17, a plastic rod are arranged.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention relates to a geomembrane damage leakage monitoring system based on distributed optical fibers, which comprises a seepage system, a heating system and a DTS (draw texturing System) system, wherein the seepage system comprises a mold groove 14 and a water supply system, the mold groove 14 is made of organic glass, the length of the mold groove 14 is 2.4m, the width of the mold groove is 0.5m, the height of the mold groove is 0.8m, an earth and rockfill dam section model 13 with the height of 0.6m is arranged in the mold groove 14, the earth and rockfill dam section model 13 is formed by stacking fine sandy soil in a layered mode, the side slopes on two sides are used as slope protection slopes, the dam body is naturally settled and compacted, the geomembrane 5 is arranged on the surface of the dam body on the upstream side, the geomembrane 5 is a composite geomembrane, one membrane is arranged, and geotextile is specially arranged for increasing the roughness of the. The water supply system provides seepage flow for the earth and rockfill dam end face model 13, and the heating system provides a heat source for the earth and rockfill dam end face model 13; the DTS system comprises an optical fiber 6, a DTS demodulation device 9 and an industrial personal computer 10 for collecting and analyzing the temperature and corresponding position information of the optical fiber 6, which are sequentially connected, wherein one part of the optical fiber 6 is arranged on one side of the geomembrane 5 close to the upstream in an S shape (see figure 2), and the arrangement length is 10 m; the rest parts of the optical fibers 6 are arranged in the end face model of the earth-rock dam in layers, the arrangement length is 16m, the optical fibers are arranged in three layers, and each layer is 10cm, 20cm and 30cm away from the dam bottom.

The optical fiber 6 is a linear multimode temperature sensing optical fiber, the DTS demodulation device 9 demodulates and records the temperature value of the optical fiber 6 in the natural cooling process, and the DTS demodulation device 9 performs distributed temperature measurement based on a Raman optical time domain emission measurement technology. When the optical fiber is used for transmission, the Raman scattering generated in the period can realize real-time measurement of the outside temperature, the Stokes light and the anti-Stokes light can form Raman scattering light, the anti-Stokes light has certain influence on the temperature, and the Stokes light has no influence on the temperature. The relationship between the reflected light intensity of the two lights received by the DTS demodulation equipment can obtain the temperature of a certain point. And measuring the time interval between the incident light and the reflected light by using an Optical Time Domain Reflectometer (OTDR) technology to obtain the position information of the point.

The heating system comprises a silicon rubber heating belt 8, the silicon rubber heating belt 8 is connected with a thermostat 11, and the thermostat 11 is connected with an alternating current power supply 12; the earth and rockfill dam section model 13 is formed by stacking sand particles, the silicon rubber heating belt 8 is wound on the plastic rod 17, and the plastic rod 17 is vertically embedded in the middle of the earth and rockfill dam end face model 13.

The water supply system comprises a water inlet pipe 1 and a water gate 3, the water gate 3 divides the bottom of the model groove 14 into a left part and a right part, and the water level is kept stably rising when the water gate position and the opening degree are adjusted to ensure that the water is stored at the upper reaches of the earth-rock dam section model. The inlet tube 1 sets up in 14 left sides tops of model groove, and earth and rockfill dam section model 13 sets up in 14 right sides of model groove, is provided with breakwater 2 between sluice 3 and the earth and rockfill dam section model 13, and breakwater 2 is fixed at 14 inner wall tops of model groove, and 2 bottoms of breakwater and the 14 bottom surfaces of model groove leave the clearance. The bottom of one side, close to the water inlet pipe 1, of the mold groove 14 is provided with a water outlet a4 for adjusting the water level in front of the dam, the bottom of the other opposite side is provided with a water outlet b7 for measuring the seepage flow, and water valves are respectively arranged on the water outlet a4 and the water outlet b 7.

When the geomembrane is damaged and leaks, the water flow can change the temperature of the optical fibers at the leaking point and on the seepage path, the DTS demodulation equipment can transmit the position information of the temperature changing point to the main control computer through an optical time domain reflection technology, and can also transmit the temperature information to the main control computer through the temperature effect of Raman scattering, so that the damaged part of the geomembrane and the leaking path can be obtained by monitoring the temperature change of each point on the optical fibers and carrying out inversion.

The invention relates to a geomembrane damage leakage monitoring method based on distributed optical fibers, which specifically comprises the following steps:

step 1: the method comprises the steps that a geomembrane 5 is arranged on one side, close to the upstream, of an earth and rock dam section model 13, optical fibers 6 are arranged on the surface of the geomembrane 5 and inside the earth and rock dam section model 13, the optical fibers 6 are wound on a PVC pipe, one part of the optical fibers 6 are arranged on the geomembrane 5 in an S shape, the rest parts of the optical fibers are arranged inside the earth and rock dam section model 13 in a layered mode, the optical fibers 6 on the bottom layer are close to the bottom of the earth and rock dam section model 13, the optical fibers 6 on the top layer are close to the top of the earth and rock dam section model 13, the initial point of the optical fibers 6 on the top of the geomembrane 5 is an optical fiber measurement initial point 16, the end part of the top end of the;

step 2: winding a silicon rubber heating belt 8 on a plastic rod 17, connecting the silicon rubber heating belt 8 with a thermostat 11 and an alternating current power supply 12, and vertically embedding the plastic rod in the center of a cross section model 13 of the earth and rockfill dam;

and step 3: injecting water into the model groove 14 through the water inlet pipe 1, opening the sluice 3 at the upstream of the earth and rockfill dam section model 13, and closing the sluice 3 after the water level at the upstream of the earth and rockfill dam section model 13 reaches a preset water level, so that the earth and rockfill dam section model forms a stable seepage field under the water level;

and 4, step 4: heating the earth and rockfill dam section model 13 by using the silicon rubber heating belt 8, wherein the temperature of the optical fiber 6 rises along with the temperature of the earth and rockfill dam section model 13, and after the temperature is heated to 85 ℃, disconnecting the alternating current power supply 12 of the silicon rubber heating belt 8 to naturally cool the optical fiber 6;

and 5: an industrial personal computer 10 is adopted to record and display the temperature change process in the natural cooling process of the optical fiber 6; recording the optical fiber 6 point with the maximum temperature change amplitude, and estimating the position of the geomembrane 5 corresponding to the optical fiber point, namely the damaged position of the geomembrane 5;

the temperature of the optical fibers arranged in the stable period basically has no change, but once the geomembrane is damaged, a part of the optical fibers arranged on the geomembrane is suddenly reduced in temperature, which indicates that the position of the optical fiber is the damaged position of the geomembrane, and the point with larger temperature reduction is the point closer to the damaged position, and the damaged position of the geomembrane is about 6.4m away from the initial end of the optical fiber;

after a period of time, the temperature of part of the optical fibers laid at the bottom in the earth and rockfill dam section model is suddenly reduced, which indicates that the leakage occurs in the sandy earth and rockfill dam section model due to the damage of the geomembrane, and the point with larger temperature drop is the place where the leakage is more remarkable, and the position where the leakage occurs in the earth and rockfill dam section model is about 21.5m away from the initial end of the optical fiber arrangement; in the later period, the temperature of the bottom optical fiber is reduced in a concentrated manner, the leakage position of the section is about 42m away from the initial end of the optical fiber arrangement, and the condition that the geomembrane is damaged to generate a leakage channel in the section model of the sandy earth-rock dam is shown;

selecting two corresponding optical fiber points as a measuring point 1 and a measuring point 2 according to the leakage position, and recording the temperature T of the optical fiber points_SMeasuring the temperature T of the water flow around the earth-rock dam section model 13_fThe leakage Q of the geomembrane at the optical fiber point_{Convection current}Comprises the following steps:

in the formula: q_vFor convective heat, Q, between the fibre and the water stream_dThe heat transferred by the water flow due to heat conduction, A_aThe heat exchange area between the optical fiber and the water flow, namely the external surface area of the optical fiber, is 0.785m in the embodiment, and h is the heat exchange coefficient (300-500W/m)²·k)，T_sIs the temperature, T, of the surface of the optical fiber_fIs the temperature of the water stream, λ_wIs the thermal conductivity coefficient of water, specifically 0.62W/m.k, T is the instantaneous temperature in the water flow conduction process, and x is the heat transfer distance of water。

The leakage Q corresponding to the measuring points 1 and 2 can be fitted through the formula_{Convection current}Are respectively 1.34cm³/s、1.31cm³S; in order to test the practical effect of the monitoring method, the leakage at the measuring points 1 and 2 is actually measured, the measurement result is shown in table 1, and as can be seen from the table, the leakage fitted by the geomembrane damage leakage monitoring method based on the distributed optical fibers has smaller difference with the actual measurement result, has higher accuracy and can be used in the actual measurement.

TABLE 1

	Fitting seepage flow, cm3/s	Measured seepage flow rate, cm3/s
			Measuring point 1	1.34	1.41
Measuring point 2	1.31	1.40