Dam and tailing body safety monitoring system and method based on optical fiber sensing technology

Abstract

The invention provides a dam and tailing body safety monitoring system and method based on an optical fiber sensing technology, and belongs to the field of dam and tailing body safety monitoring and early warning. A plurality of safety monitoring wells are distributed at the top of a dam or a tailing body, safety monitoring specially-made armored optical cables are arranged on the top and a downstream face layered filling body in a neural network shape or a hairpin ring shape, and safety monitoring specially-made armored optical cables are arranged under the safety monitoring wells in a series connection mode. The safety monitoring specially-made armored optical cable is connected with a composite modulation-demodulation instrument in a monitoring room, and the composite modulation-demodulation instrument is connected with a super computer workstation. The device is used for comprehensively monitoring formicary cavities, cracks, erosion and seepage in a dam or tailing body structure, stability and three-dimensional deformation of the dam or tailing body, and static liquefaction and hidden water saturation areas in the dam body.

Description

Technical Field

[0001] This invention belongs to the field of dam and tailings safety monitoring and early warning, specifically involving a dam and tailings safety monitoring system and method based on fiber optic sensing technology. Background Technology

[0002] A dam, or water dam, is a water-retaining structure built of materials such as earth, rock, or concrete. It forms a reservoir by intercepting river flow and is primarily used for flood control, water supply, irrigation, hydroelectric power generation, and improving navigation. Dams can be classified by structure into gravity dams and arch dams, and by material into earth-rock dams and concrete dams. Additionally, river regulation structures such as groynes, longitudinal dams, and submerged dams also fall under the category of dams. A tailings body refers to a site formed by damming valley mouths or enclosing land to store tailings discharged after the beneficiation of metallic and non-metallic ores.

[0003] Tailings are essential facilities for maintaining normal mine production, but they are also a major hazard source in metal and non-metal mines. As a man-made debris flow hazard source with high potential energy, a collapse or dam failure of a tailings body will cause huge losses to the safety of life and property downstream and serious pollution to the surrounding environment.

[0004] Many dams and tailings bodies suffer from incomplete monitoring systems, outdated monitoring technologies, and a lack of professional monitoring personnel. Some are completely unmonitored, while others are regularly measured on-site using traditional instruments, but these are subject to systemic and human errors due to weather, human factors, and site conditions. All of these factors negatively impact the safety production and management of dams and tailings bodies. Therefore, adopting modern communication, electronic equipment, and computer technology to achieve real-time and automatic monitoring of dam and tailings body indicators is an essential path for the safety supervision of dams and tailings bodies.

[0005] Tailings dams are among the world's largest and most complex engineering systems, carrying significant risks. These evolving systems typically expand over decades and are continuously affected by variable load conditions, saturation fluctuations, and environmental stresses. Following several high-profile failures in recent years, the industry has undergone a fundamental shift. The introduction of the Global Tailings Management Industry Standard (GISTM) has elevated monitoring from a previously optional operational option to a compliance requirement at the decision-making level. GISTM's tenth principle explicitly requires operators to implement tiered reviews as part of a robust quality and risk management system throughout all stages of the tailings facility's lifecycle, including the closure phase. However, traditional industry practices rely heavily on discrete point sensors, such as piezometers and inclinometers, which creates significant data blind spots in practical applications. Attempting to monitor a 5-kilometer-long dam with twenty point sensors is like trying to see an entire landscape through a keyhole: while obtaining high-resolution local data, it loses the overall contextual information of the areas where failures often first occur.

[0006] Traditional safety monitoring of dams and tailings bodies or tailings ponds generally uses various sensors and their matching measuring instruments and equipment buried sparsely on the surface or inside of the dam and tailings body for fixed-point measurement. This method cannot perform distributed or high-density quasi-distributed real-time continuous dynamic monitoring of the entire dam and tailings body, both inside and out.

[0007] Uncontrolled seepage within dams and tailings bodies can trigger internal erosion (also known as piping), gradually eroding and destroying the dam's core wall. Because discrete point piezometers are typically sparsely deployed, local seepage channels often "traverse" between different point sensors, thus being missed by traditional monitoring methods.

[0008] Uneven settlement and shear displacement of the dam and tailings body can generate tensile cracks in the dam body, thereby weakening the overall structural integrity.

[0009] Early signs of static liquefaction, hidden saturation zones, or internal erosion are invisible to most conventional monitoring instruments.

[0010] Fiber optic sensing systems can be used to measure ground three-component seismic signals and underground pressure, temperature, humidity, stress, noise, vibration, sound waves, seismic waves, flow rate, component analysis, electric field, and magnetic field. The system is based on a fully armored fiber optic cable structure, with distributed sensors and connection / data transmission cables all made of optical fiber.

[0011] Distributed Fiber Optic Sensing (DFOS) technology is changing this paradigm. By transforming ordinary fiber optic cables into thousands of continuous sensing units, DFOS technology creates a "central nervous system" for dams and tailings ponds, enabling early identification of potential risks. It is not only a monitoring tool, but also a strategic asset supporting GIS™ compliance, insurance verification, and long-term risk resilience.

[0012] With the rapid development of distributed optical fiber sensing technology, specially designed high-sensitivity armored optical cables for dam and tailings safety monitoring can be easily deployed or permanently buried on the top and outside of dams and tailings bodies, as well as inside the dam body. This enables real-time, continuous, high-density distributed measurement and uninterrupted monitoring of various dam and tailings body parameters, overcoming and solving the problem that sparsely distributed dam and tailings body safety monitoring sensors are difficult to continuously monitor the safety hazards and risks inside and outside the entire dam and tailings body in real time. Summary of the Invention

[0013] To achieve real-time, continuous, high-density distributed measurement and uninterrupted monitoring of various parameters of dams, tailings bodies, and their surrounding areas, promptly identify potential hazards and risk areas affecting dam and tailings safety, issue early warnings, and promptly address and reinforce identified safety hazards and analyzed dam and tailings sections to ensure the long-term safety and stability of dams and tailings, this invention proposes a dam and tailings safety monitoring system and method based on distributed fiber optic sensing technology.

[0014] The specific technical solution is as follows:

[0015] A dam and tailings safety monitoring system based on fiber optic sensing technology includes a dam or tailings body. Multiple safety monitoring wells are distributed along the top of the dam or tailings body. A specially designed armored optical cable for safety monitoring is arranged in a neural network or "hairpin ring" pattern on the top of the dam or tailings body and the layered fill on the backwater side. The specially designed armored optical cable is also connected in series under the safety monitoring wells. The specially designed armored optical cable is connected to a composite modulation and demodulation instrument in the monitoring room. The composite modulation and demodulation instrument is connected to a supercomputer workstation. The composite modulation and demodulation instrument is a multi-channel distributed acoustic wave sensor, strain or deformation sensor, and active heating temperature sensor composite modulation and demodulation instrument. The supercomputer workstation is used for monitoring data storage, processing, analysis, and early warning signal dissemination.

[0016] Furthermore, the specially armored optical cable for safety monitoring includes strain or deformation sensing units, temperature sensing units, and acoustic wave sensing units. The outer layer is equipped with an armored stainless steel wire stranded protective sheath.

[0017] The strain or deformation sensing unit is a spiral distributed optical fiber three-dimensional strain or deformation sensing (DSS) unit;

[0018] The temperature sensing unit is an Active Heating Distributed Fiber Optic Temperature Sensing (AH-DTS) unit;

[0019] The acoustic sensing unit is a distributed optical fiber acoustic sensing (DAS) unit.

[0020] Specifically:

[0021] The strain or deformation sensing unit has a built-in cylindrical elastomer with a diameter of about 1 to 3 centimeters. A first single-mode optical fiber with high sensitivity, high reflectivity and hydrogen loss resistance is wound around the elastomer at an angle of 30 to 60 degrees to the extension direction of the elastomer. A layer of high-strength waterproof composite material is tightly extruded on the outside of the first single-mode optical fiber. The high-strength waterproof composite material is then tightly encapsulated by at least one layer of high-strength flexible composite material sheath.

[0022] The temperature sensing unit incorporates two high-sensitivity, high-reflectivity, hydrogen-loss-resistant multimode optical fibers. These fibers are sequentially surrounded by a first thin stainless steel tube, a carbon fiber heating or copper mesh heating resistance wire sleeve, and a high-strength, flexible, insulating, and waterproof composite material sheath. The two multimode optical fibers are fused into a U-shape at the cable's tail end, with a U-shaped stainless steel tube at the splice to protect the fused fibers. The temperature sensing unit is used for high-precision, dual-ended input AH-DTS measurements.

[0023] The acoustic wave sensing unit has a built-in high-sensitivity, high-reflectivity, hydrogen-loss-resistant second single-mode optical fiber, which is deployed inside a second thin stainless steel tube.

[0024] Both the first and second single-mode optical fibers are equipped with extinction devices at their tails.

[0025] The 3D-DSS signal input port of the composite modulation and demodulation instrument is connected to the first single-mode fiber in the strain or deformation sensing unit, the two AH-DTS signal ports are connected to the two multimode fibers in the temperature sensing unit, the current output port is connected to the carbon fiber heating or copper mesh heating resistance wire mesh sleeve, and the DAS signal port is connected to the second single-mode fiber in the acoustic wave sensing unit.

[0026] The monitoring method for dam and tailings body safety monitoring systems based on fiber optic sensing technology includes the following steps:

[0027] (a) Drill a series of safety monitoring wells down to the bedrock layer on top of the dam or tailings body in a grid of 10m x 10m or 25m x 25m;

[0028] (b) Excavate a neural network of shallow trenches on the top and backwater layered fill of the dam or tailings body, lay a special armored optical cable for safety monitoring in the trenches, and then inject cement grout into the trenches to permanently fix the special armored optical cable for safety monitoring on the top and backwater layered fill of the dam or tailings body.

[0029] (c) A specially armored optical cable for safety monitoring is installed in series in the underground safety monitoring well. Then, cement grout is injected into the well to permanently fix the specially armored optical cable for safety monitoring to the top of the dam or tailings body.

[0030] (d) Install composite modulation and demodulation instruments in the monitoring room, and a supercomputer workstation for monitoring data storage, processing, analysis and early warning signal dissemination;

[0031] (e) Connect the 3D-DSS signal input port of the composite modulator-demodulator to the first single-mode fiber in the strain or deformation sensing unit inside the specially armored optical cable for safety monitoring.

[0032] (f) Connect the 3D-DSS signal input port of the composite modulator-demodulator to the two AH-DTS signal ports in the special armored optical cable for safety monitoring and to the two multimode optical fibers in the temperature sensing unit. Connect the current output port of the composite modulator-demodulator to the carbon fiber heating or copper mesh heating resistance wire mesh sleeve.

[0033] (g) Connect the DAS signal port of the composite modulation and demodulation instrument to the second single-mode fiber of the acoustic wave sensing unit inside the specially armored optical cable for safety monitoring.

[0034] (h) Connect the composite modem to the supercomputer workstation;

[0035] (i) Start the composite modulation and demodulation instrument;

[0036] (j) The composite modulation and demodulation instrument continuously acquires and monitors the distributed three-dimensional strain or deformation data, distributed temperature rise curve data and distributed fluid noise data of the specially armored optical cable for safety monitoring in real time;

[0037] (k) The composite modulation and demodulation instrument modulates and demodulates the continuously acquired distributed three-dimensional strain or deformation data, distributed temperature rise curve data and distributed fluid noise data in real time, and then transmits them to the supercomputer workstation.

[0038] (l) The supercomputer workstation performs real-time processing and analysis on the distributed three-dimensional strain or deformation data, distributed temperature rise curve data and distributed fluid noise data monitored in real time, and obtains the strain or deformation and strain gradient or deformation gradient change data of the layered fill body on the top and backwater surface of the dam or tailings body and the internal structure, and safely monitors the distributed temperature rise curve data and distributed fluid noise data along the specially armored optical cable.

[0039] (m) Process and analyze the strain or deformation data and strain gradient (i.e. strain rate data) or deformation gradient (i.e. deformation rate data) collected in real time by the strain or deformation sensing unit of the specially armored optical cable for safety monitoring. Monitor and understand the changes of stress field in three-dimensional space over time on the top and backwater layered fill body of the dam or tailings body and various parts of the internal structure. A sudden drop in the shear modulus of the dam body may indicate an increase in water saturation, structural defects or static liquefaction risk inside the dam body. This facilitates the timely detection of dam or tailings body parts with abnormal strain or deformation. Analyze and monitor the potential risks and possibilities of abnormal stress field and abnormal strain or deformation dam or tailings body parts inducing crack zones or rupture zones. Provide early warning information on the safety risks of crack zones or rupture zones that may appear in the dam or tailings body in a timely manner.

[0040] (n) Carefully observe and analyze the distributed temperature rise curve data collected in real time by the temperature sensing unit of the special armored optical cable for safety monitoring; when the temperature rise curve of the special armored optical cable for safety monitoring is higher or lower than the average temperature rise curve of the dam or tailings body at the location inside the dam or tailings body, it may be that the groundwater inside the dam or tailings body has moved or the water inside the dam has seeped into the vicinity of the monitoring range of the special armored optical cable for safety monitoring. Closely monitor the safety risks of static liquefaction and hidden water saturation areas in the dam or tailings body where the temperature rise curve is abnormal. Before visible muddy water appears on the downstream slope, accurately locate the seepage channel and issue early warning information of safety risks inside the dam body in a timely manner.

[0041] (o) Carefully observe and analyze the distributed fluid noise data collected in real time by the acoustic wave sensing unit of the specially armored optical cable for safety monitoring. When fluid noise appears along the specially armored optical cable for safety monitoring in the location inside the dam or tailings body, it may be that the water inside the dam or tailings body has seeped, leaked, or piped along the ant holes, cavities, cracks or rupture zones in the dam body and reached the vicinity of the monitoring range of the specially armored optical cable for safety monitoring. Closely monitor the dam or tailings body where the fluid noise is abnormal and there are potential major safety risks such as seepage, leakage and piping, and issue early warning information of major safety risks inside the dam body in a timely manner.

[0042] (p) During the real-time continuous safety monitoring of dams or tailings bodies, the supercomputer workstation performs multi-dimensional, multi-parameter, and multi-scale real-time comprehensive processing and analysis on the collected distributed three-dimensional strain or deformation data, distributed temperature rise curve data, and distributed fluid noise data. If any part of the dam or tailings body simultaneously exhibits abnormal stress field, abnormal strain or deformation, abnormal temperature rise curve (ΔT vs time), and abnormal fluid noise, an early warning message indicating a significant safety risk to the dam or tailings body must be issued immediately. A detailed inspection and thorough exploration of the abnormal sections of the dam or tailings body must be conducted immediately to promptly identify potential major safety risk areas such as anthills, cavities, cracks, fracture zones, seepage, leaks, piping, landslides, or collapses. Real-time monitoring of the layered fill on the top and backwater surfaces of the dam or tailings body, as well as the internal erosion and seepage of the internal structure, the stability and three-dimensional deformation of the dam or tailings body, static liquefaction within the dam body, and hidden water-saturated zones must be implemented. On-site measures such as piling, reinforcement, grouting, and filling cracks or fracture zones must be taken to ensure the safety and stability of the dam or tailings body without any mishaps.

[0043] The specific technical effects of this invention are as follows:

[0044] This invention proposes a safety monitoring system and method for dams and tailings bodies based on distributed optical fiber sensing technology. It utilizes specially armored optical cables arranged in a neural network or "hairpin ring" pattern on the top and backwater surfaces of the dam and tailings bodies, and multiple specially armored optical cables serially deployed underground along the extension direction of the dam or tailings body. This system monitors and measures parameters such as strain or deformation, temperature rise curves, fluid noise, and groundwater level changes in the dam and tailings body in real time. It comprehensively monitors internal erosion and seepage of the dam or tailings body structure, stability and three-dimensional deformation of the dam or tailings body, static liquefaction within the dam body, and hidden water-saturated zones. It allows for timely reinforcement of areas prone to tailings landslides or dam failures, and the issuance of early warnings or forecasts to prevent geological disasters. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the deployment of the dam and tailings body safety monitoring system based on distributed optical fiber sensing technology according to the present invention.

[0046] Figure 2 This is a schematic diagram of the cross-sectional structure of the specially armored optical cable structure for dam and tail safety monitoring according to the present invention.

[0047] Figure 3 This is a schematic diagram of the strain or deformation sensing unit, temperature sensing unit, and sound wave sensing unit of the present invention. Detailed Implementation

[0048] To facilitate understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings illustrate preferred embodiments of the invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. They are not intended to limit the invention, but are merely illustrative, and the advantages of the invention will become clearer and easier to understand by illustrating them.

[0049] like Figure 1 The schematic diagram of the deployment of a dam and tailings safety monitoring system based on distributed optical fiber sensing technology is shown. It includes a dam or tailings body 1. Multiple safety monitoring wells 3 are distributed along the extension direction of the dam or tailings body at the top of the dam or tailings body 1. Specially armored safety monitoring optical cables 2 are arranged in a neural network or "hairpin ring" pattern on the top of the dam or tailings body 1 and the layered fill on the backwater side. Specially armored safety monitoring optical cables 2 are connected in series below the safety monitoring wells 3. The specially armored safety monitoring optical cables 2 are connected to a composite modulation and demodulation instrument 5 in the monitoring room 4. The composite modulation and demodulation instrument 5 is connected to a supercomputer workstation 11. The composite modulation and demodulation instrument 5 is a multi-channel distributed acoustic wave sensor, strain or deformation sensor, and active heating temperature sensor composite modulation and demodulation instrument. The supercomputer workstation 11 is used for monitoring data storage, processing, analysis, and early warning signal dissemination.

[0050] like Figure 2 and Figure 3 As shown, the specially armored optical cable 2 for safety monitoring includes a strain or deformation sensing unit 6, a temperature sensing unit 7, and an acoustic wave sensing unit 8. The outer layer is provided with an armored stainless steel wire stranded protective sheath 10.

[0051] The strain or deformation sensing unit 6 is a spiral distributed optical fiber three-dimensional strain or deformation sensing 3D-DSS unit.

[0052] Temperature sensing unit 7 is an active heating distributed fiber optic temperature sensing AH-DTS unit;

[0053] The acoustic wave sensing unit 8 is a distributed optical fiber acoustic wave sensing (DAS) unit.

[0054] The strain or deformation sensing unit 6 has a built-in cylindrical elastomer 61 with a diameter of about 1 to 3 centimeters. A first single-mode optical fiber 62 with high sensitivity, high reflectivity and hydrogen loss resistance is wound around the elastomer 61 at an angle of 30 to 60 degrees with the extension direction of the elastomer 61. A layer of high-strength waterproof composite material 63 is tightly extruded on the outside of the first single-mode optical fiber 62. The high-strength waterproof composite material 63 is tightly encapsulated by at least one layer of high-strength flexible composite material sheath 64.

[0055] The temperature sensing unit 7 contains two high-sensitivity, high-reflectivity, hydrogen-loss-resistant multimode optical fibers 71. The multimode optical fibers 71 are sequentially surrounded by a first thin stainless steel tube 72, a carbon fiber heating or copper mesh heating resistance wire sleeve 73, and a high-strength, flexible, insulating, and waterproof composite material sheath 74. The two multimode optical fibers 71 are fused into a U-shape at the end of the optical cable, with a U-shaped stainless steel tube at the splice point protecting the fused multimode optical fibers 71. The temperature sensing unit 7 is used for high-precision dual-ended input AH-DTS measurement.

[0056] The acoustic wave sensing unit 8 has a built-in high-sensitivity, high-reflectivity, hydrogen-loss-resistant second single-mode optical fiber 81, which is arranged inside the second thin stainless steel tube 82.

[0057] Both the first single-mode fiber 62 and the second single-mode fiber 81 are equipped with extinction devices 9 at their ends.

[0058] The 3D-DSS signal input port of the composite modulation and demodulation instrument 5 is connected to the first single-mode fiber 62 in the strain or deformation sensing unit 6, the two AH-DTS signal ports are connected to the two multimode fibers 71 in the temperature sensing unit 7, the current output port is connected to the carbon fiber heating or copper mesh heating resistance wire mesh sleeve 73, and the DAS signal port is connected to the second single-mode fiber 81 in the acoustic wave sensing unit 8.

[0059] The monitoring method for the dam and tailings body safety monitoring system based on fiber optic sensing technology includes the following steps:

[0060] (a) Drill a series of safety monitoring wells 3 into the bedrock layer on the top of the dam or tailings body 1 in a grid of 10 m x 10 m or 25 m x 25 m;

[0061] (b) Excavate a neural network of shallow trenches on the top and backwater layered fill of the dam or tailings body 1. Lay a specially armored optical cable 2 for safety monitoring within the trenches, and then inject cement grout into the trenches to permanently fix the specially armored optical cable 2 to the top and backwater layered fill of the dam or tailings body 1. Best practice is to lay the specially armored optical cable 2 in a "hairpin loop". Even if the cable is cut by an excavator, the composite modem 5 can immediately obtain data from the other end of the loop, ensuring the continuity of monitoring.

[0062] (c) Safety monitoring specially armored optical cables 2 are connected in series under multiple safety monitoring wells 3 distributed along the extension direction of the dam or tailings body 1. Then, cement grout is injected into the wells to permanently fix the safety monitoring specially armored optical cables 2 under the safety monitoring wells 3 at the top of the dam or tailings body 1.

[0063] (d) Install a composite modulation and demodulation instrument 5 in the monitoring room 4, and a supercomputer workstation 11 for monitoring data storage, processing, analysis and early warning signal release;

[0064] (e) Connect the 3D-DSS signal input port of the composite modulation and demodulation instrument 5 to the first single-mode fiber 62 in the strain or deformation sensing unit 6 inside the special armored optical cable 2 for safety monitoring.

[0065] (f) Connect the 3D-DSS signal input port of the composite modulator-demodulator 5 to the two AH-DTS signal ports in the special armored optical cable 2 for safety monitoring and to the two multimode optical fibers 71 in the temperature sensing unit 7. Connect the current output port of the composite modulator-demodulator 5 to the carbon fiber heating or copper mesh heating resistance wire mesh sleeve 73.

[0066] (g) Connect the DAS signal port of the composite modulation and demodulation instrument 5 to the second single-mode fiber 81 in the acoustic wave sensing unit 8 of the special armored optical cable 2 for safety monitoring.

[0067] (h) Connect the composite modulation and demodulation instrument (5) to the supercomputer workstation 11 used for monitoring data storage, processing and analysis;

[0068] (i) Activate the composite modulation and demodulation instrument 5, which is connected to the specially armored optical cable 2 for safety monitoring, which is laid out in a neural network on the top and backwater surface of the dam or tailings body 1, and the specially armored optical cable 2 for safety monitoring, which is laid out in series under the multiple safety monitoring wells 3.

[0069] (j) The composite modulation and demodulation instrument 5 continuously collects and monitors distributed three-dimensional strain or deformation data, distributed temperature rise curve (ΔT vs time) data and distributed fluid noise data on the top and backwater layered fill of the dam or tailings body 1 and around all safety monitoring wells 3 along the specially armored optical cable 2 for safety monitoring in real time.

[0070] (k) The composite modulation and demodulation instrument 5 modulates and demodulates the continuously acquired distributed three-dimensional strain or deformation data, distributed temperature rise curve (ΔT vs time) data and distributed fluid noise data in real time, and then transmits them to the supercomputer workstation 11 next to it for monitoring data storage, processing and analysis.

[0071] (l) The supercomputer workstation 11 has a dedicated software system for processing and analyzing safety monitoring data of the dam or tailings body 1. It processes and analyzes the distributed three-dimensional strain or deformation data, distributed temperature rise curve (ΔT vs time) data and distributed fluid noise data monitored in real time, and obtains the strain or deformation and strain gradient or deformation gradient change data of the layered fill body on the top and backwater surface of the dam or tailings body 1 and the internal structure. It also monitors the distributed temperature rise curve (ΔT vs time) data and distributed fluid noise data along the specially armored optical cable 2.

[0072] (m) The strain or deformation data and strain gradient (i.e. strain rate data) or deformation gradient (i.e. deformation rate data) along the extension direction of the dam or tailings body 1 are collected in real time by the strain or deformation sensing unit 6 along the specially armored optical cable 2 for safety monitoring of the dam or tailings body 1. The strain or deformation data are processed and analyzed to monitor and understand the changes of stress field in three-dimensional space with time on the top and backwater layered fill body and internal structure of the dam or tailings body 1. A sudden drop in the shear modulus of the dam body may indicate that the water saturation inside the dam body has increased, structural defects or static liquefaction risk. It is convenient to detect the parts of the dam or tailings body 1 with abnormal strain or deformation in a timely manner. The potential risks and possibilities of abnormal stress field and abnormal strain or deformation of the dam or tailings body 1 inducing crack zones or rupture zones are analyzed and monitored. Early warning information of safety risks of crack zones or rupture zones in the dam or tailings body 1 is provided in a timely manner.

[0073] (n) Carefully observe and analyze the distributed temperature rise curve (ΔT vs time) data collected in real time by the temperature sensing unit 7 along the specially armored optical cable 2 for safety monitoring. Seepage water has different thermal characteristics compared to the surrounding soil. The distributed temperature rise curve (ΔT vs time) can be identified at the moment when the temperature is abnormal due to fluid movement, thus achieving true early warning. When the temperature rise curve (ΔT vs time) of the specially armored optical cable 2 along the dam or tailings body 1 is higher or lower than the average of the dam or tailings body 1, it may be due to the migration of groundwater inside the dam or tailings body 1 or the leakage of water from the dam into the vicinity of the monitoring range of the specially armored optical cable 2. Close attention should be paid to the safety risks of static liquefaction and hidden water saturation zones at the dam or tailings body 1 where the temperature rise curve (ΔT vs time) is abnormal. Before visible turbid water appears on the downstream slope, the seepage channel should be accurately located and early warning information of safety risks inside the dam should be issued in a timely manner.

[0074] (o) Carefully observe and analyze the distributed fluid noise data collected in real time by the acoustic sensing unit 8 along the specially armored optical cable 2 for safety monitoring. When fluid noise appears along the specially armored optical cable 2 inside the dam or tailings body 1, it may be that the water inside the dam or tailings body 1 has leaked, seeped, or piped along the ant holes, cavities, cracks or rupture zones in the dam body and reached the vicinity of the monitoring range of the specially armored optical cable 2 for safety monitoring. That is, the DAS signal "heard" the acoustic turbulence generated when the water flow passes through the piping cavity. We should pay close attention to the dam or tailings body 1 where the fluid noise is abnormal and there are potential major safety risks such as seepage, leakage and piping. We should issue early warning information on major safety risks inside the dam body in a timely manner.

[0075] (p) During the real-time continuous safety monitoring of the dam or tailings body 1, the supercomputer workstation 11 performs multi-dimensional, multi-parameter, and multi-scale real-time comprehensive processing and analysis on the collected distributed three-dimensional strain or deformation data, distributed temperature rise curve data, and distributed fluid noise data. Once any part of the dam or tailings body 1 simultaneously exhibits abnormal stress field, abnormal strain or deformation, abnormal temperature rise curve, and abnormal fluid noise, an early warning message indicating a major safety risk to the dam or tailings body 1 should be issued immediately. Detailed inspection and careful exploration of the abnormal sections of the dam or tailings body 1 should be carried out immediately to promptly identify potential major safety risk sections on the dam or tailings body 1, such as ant holes, cavities, crack zones, rupture zones, seepage, leakage, piping, landslides, or collapses. Real-time monitoring should be conducted on the layered fill bodies on the top and backwater surfaces of the dam or tailings body 1, as well as the internal erosion and seepage of the internal structure of the dam or tailings body 1, the stability and three-dimensional deformation of the dam or tailings body, the static liquefaction inside the dam body, and the hidden water-saturated zones.

Claims

1. A dam and tailings body safety monitoring system based on fiber optic sensing technology, characterized in that, The dam or tailings body (1) includes multiple safety monitoring wells (3) distributed along the extension direction of the dam or tailings body at the top of the dam or tailings body (1). The top of the dam or tailings body (1) and the backwater layered fill body are covered with a neural network or "hairpin ring" pattern of specially armored optical cables (2) for safety monitoring. The specially armored optical cables (2) for safety monitoring are connected in series under the safety monitoring wells (3). The specially armored optical cables (2) for safety monitoring are connected to the composite modulation and demodulation instrument (5) in the monitoring room (4). The composite modulation and demodulation instrument (5) is connected to the supercomputer workstation (11). The composite modulation and demodulation instrument (5) is a multi-channel distributed acoustic wave sensor, strain or deformation sensor, and active heating temperature sensor composite modulation and demodulation instrument. The supercomputer workstation (11) is used for monitoring data storage, processing, analysis and early warning signal release.

2. The dam and tailings body safety monitoring system based on fiber optic sensing technology according to claim 1, characterized in that, The specially armored optical cable (2) for safety monitoring includes a strain or deformation sensing unit (6), a temperature sensing unit (7), and an acoustic wave sensing unit (8); the outer layer is provided with an armored stainless steel wire twisted protective sheath (10). The strain or deformation sensing unit (6) is a spiral distributed optical fiber three-dimensional strain or deformation sensing unit; The temperature sensing unit (7) is an active heating distributed optical fiber temperature sensing unit; The acoustic wave sensing unit (8) is a distributed optical fiber acoustic wave sensing unit.

3. The dam and tailings body safety monitoring system based on fiber optic sensing technology according to claim 2, characterized in that, The strain or deformation sensing unit (6) has a cylindrical elastomer (61) built in, and a first single-mode optical fiber (62) with high sensitivity, high reflection coefficient and hydrogen loss resistance is wound on the elastomer (61) at an angle of 30 to 60 degrees with the extension direction of the elastomer (61). A layer of high-strength waterproof composite material (63) is tightly extruded on the outside of the first single-mode optical fiber (62), and at least one layer of high-strength flexible composite material sheath (64) tightly encapsulates the high-strength waterproof composite material (63). The temperature sensing unit (7) has two high-sensitivity, high-reflectivity, hydrogen-damage resistant multimode optical fibers (71) inside. The multimode optical fibers (71) are provided with a first thin stainless steel tube (72), a carbon fiber heating or copper mesh heating resistance wire mesh sleeve (73), and a high-strength flexible insulating waterproof composite material sheath (74) in sequence. The two multimode optical fibers (71) are fused into a U-shape at the end of the optical cable. A U-shaped stainless steel tube is provided at the fusion point to protect the fused multimode optical fibers (71). The temperature sensing unit (7) is used for high-precision dual-end input AH-DTS measurement. The acoustic wave sensing unit (8) has a built-in high-sensitivity, high-reflectivity, hydrogen-damage resistant second single-mode optical fiber (81), which is laid inside the second thin stainless steel tube (82).

4. The dam and tailings body safety monitoring system based on fiber optic sensing technology according to claim 3, characterized in that, Both the first single-mode fiber (62) and the second single-mode fiber (81) are equipped with extinction devices (9) at their ends.

5. The dam and tailings body safety monitoring system based on fiber optic sensing technology according to claim 4, characterized in that, The 3D-DSS signal input port of the composite modulation and demodulation instrument (5) is connected to the first single-mode fiber (62) in the strain or deformation sensing unit (6), the two AH-DTS signal ports are connected to the two multimode fibers (71) in the temperature sensing unit (7), the current output port is connected to the carbon fiber heating or copper mesh heating resistance wire mesh sleeve (73), and the DAS signal port is connected to the second single-mode fiber (81) in the acoustic wave sensing unit (8).

6. A method for safety monitoring of dams and tailings bodies based on fiber optic sensing technology, characterized in that, The method of using the dam and tailings body safety monitoring system based on fiber optic sensing technology as described in any one of claims 1 to 5 includes the following steps: (a) Drill a series of safety monitoring wells (3) into the bedrock layer at the top of the dam or tailings body (1) in a grid of 10 m x 10 m or 25 m x 25 m; (b) Excavate a neural network-shaped shallow trench on the top and backwater layered fill body of the dam or tailings body (1), lay a special armored optical cable (2) for safety monitoring in the shallow trench, and then inject cement grout into the shallow trench to permanently fix the special armored optical cable (2) for safety monitoring on the top and backwater layered fill body of the dam or tailings body (1). (c) A special armored optical cable (2) for safety monitoring is installed in series under the safety monitoring well (3), and then cement grout is injected into the well to permanently fix the special armored optical cable (2) under the safety monitoring well (3) at the top of the dam or tailings body (1). (d) Install a composite modulation and demodulation instrument (5) in the monitoring room (4) and a supercomputer workstation (11) for monitoring data storage, processing, analysis and early warning signal release. (e) Connect the 3D-DSS signal input port of the composite modulation and demodulation instrument (5) to the first single-mode fiber (62) in the strain or deformation sensing unit (6) inside the special armored optical cable (2) for safety monitoring. (f) Connect the 3D-DSS signal input port of the composite modulator (5) to the two AH-DTS signal ports in the special armored optical cable (2) for safety monitoring and to the two multimode optical fibers (71) in the temperature sensing unit (7), and connect the current output port of the composite modulator (5) to the carbon fiber heating or copper mesh heating resistance wire mesh sleeve (73). (g) Connect the DAS signal port of the composite modulation and demodulation instrument (5) to the second single-mode fiber (81) of the acoustic wave sensing unit (8) in the special armored optical cable (2) for security monitoring. (h) Connect the composite modem (5) to the supercomputer workstation (11); (i) Start the composite modulation and demodulation instrument (5); (j) The composite modulation and demodulation instrument (5) continuously collects and monitors the distributed three-dimensional strain or deformation data, distributed temperature rise curve data and distributed fluid noise data on the special armored optical cable (2) for safety monitoring in real time; (k) The composite modulation and demodulation instrument (5) modulates and demodulates the continuously collected distributed three-dimensional strain or deformation data, distributed temperature rise curve data and distributed fluid noise data in real time, and then transmits them to the supercomputer workstation (11). (l) The supercomputer workstation (11) performs real-time processing and analysis on the distributed three-dimensional strain or deformation data, distributed temperature rise curve data and distributed fluid noise data monitored in real time, and obtains the three-dimensional strain or deformation and three-dimensional strain gradient or deformation gradient change data of the dam or tailings body (1) top and backwater layered filling body and internal structure, and safely monitors the distributed temperature rise curve data and distributed fluid noise data along the specially armored optical cable (2); (m) The three-dimensional strain or deformation data and strain gradient, i.e. strain rate data or deformation gradient, i.e. deformation rate data collected in real time by the three-dimensional strain or deformation sensing unit (6) of the special armored optical cable (2) for safety monitoring are processed and analyzed. The stress field of the top and backwater layered filling body of the dam or tailings body (1) and the internal structure of each part changes in the three-dimensional space with time. The sudden drop in the shear modulus of the dam body may indicate that the water saturation inside the dam body has increased, structural defects or static liquefaction risk. It is convenient to discover the parts of the dam or tailings body (1) with abnormal three-dimensional strain or abnormal three-dimensional deformation in a timely manner. The potential risks and possibilities of the abnormal three-dimensional geostress field and the abnormal three-dimensional strain or deformation of the dam or tailings body (1) induced by crack zone or fracture zone are analyzed and monitored. The early warning information of the safety risks of crack zone or fracture zone of dam or tailings body (1) is provided in a timely manner. (n) Carefully observe and analyze the distributed temperature rise curve data collected in real time by the temperature sensing unit (7) of the special armored optical cable (2) for safety monitoring; when the temperature rise curve of the special armored optical cable (2) along the line of the safety monitoring appears higher or lower than the average temperature rise curve of the dam or tailings body (1) at the location inside the dam or tailings body (1), it may be that the groundwater inside the dam or tailings body (1) has moved or the water inside the dam has leaked into the vicinity of the monitoring range of the special armored optical cable (2). Closely monitor the safety risks of static liquefaction and hidden water-bearing and water-saturated areas in the dam or tailings body (1) where the temperature rise curve is abnormal. Before visible muddy water appears on the downstream slope, accurately locate the leakage channel and issue early warning information of safety risks inside the dam in a timely manner. (o) Carefully observe and analyze the distributed fluid noise data collected in real time by the acoustic sensing unit (8) of the special armored optical cable (2) for safety monitoring. When fluid noise appears in the dam or tailings body (1) along the special armored optical cable (2), it may be that the water in the dam or tailings body (1) has leaked, seeped or piped along the ant holes, cavities, cracks or ruptures in the dam body to the vicinity of the monitoring range of the special armored optical cable (2). Closely monitor the dam or tailings body (1) where the fluid noise is abnormal and seepage, leakage and piping are potential major safety risks. Issue early warning information of major safety risks in the dam body in a timely manner. (p) During the real-time continuous safety monitoring of the dam or tailings body (1), the supercomputer workstation (11) performs multi-dimensional, multi-parameter, and multi-scale real-time comprehensive processing and analysis on the collected distributed three-dimensional strain or deformation data, distributed temperature rise curve data, and distributed fluid noise data; once any part of the dam or tailings body (1) simultaneously exhibits abnormal geostress field and abnormal strain or deformation, abnormal temperature rise curve, and abnormal fluid noise, it shall immediately issue a warning that the dam or tailings body (1) has a major safety risk. Upon receiving the early warning information, immediately conduct detailed inspections and careful explorations of abnormal sections of the dam or tailings body (1), promptly identify potential major safety risk sections such as ant holes, cavities, crack zones, rupture zones, seepage, leakage, piping, landslides or collapses on the dam or tailings body (1), and monitor in real time the internal erosion and seepage of the layered fill body on the top and backwater surface of the dam or tailings body (1) and the internal structure of the dam or tailings body (1), the stability and three-dimensional deformation of the dam or tailings body, the static liquefaction inside the dam body and the hidden water-saturated areas.

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