Full-dam-section distributed optical fiber temperature monitoring method for small and medium-sized concrete gravity dams

Abstract

The invention discloses a distributed optical fiber temperature monitoring method for full dam sections of small and medium-sized concrete gravity dams, and belongs to the field of water conservancy and hydropower engineering construction technologies. The invention aims to solve the problems of discrete data volume, short measurement period, small measurement range and the like in the temperature monitoring of the existing small and medium-sized concrete gravity dam and the stricter requirement of high and cold high-altitude areas on concrete temperature control. In order to achieve the target, the technical scheme adopted by the invention comprises the following steps: a full-dam optical fiber overall arrangement type covers a full-dam section; different warehouse surface optical fiber arrangement modes comprise a bow-shaped mode, a W-shaped mode and a variable W-shaped mode so as to adapt to warehouse surfaces with different sizes; determining the number and the arrangement positions of the temperature measurement hosts according to the arrangement types of the optical fiber temperature measurement hosts; the system can monitor the temperature change of the whole dam section and the whole life cycle of the concrete dam in real time, provides help for adjustment of temperature control measures in the dam construction period and safety monitoring in the operation period, and has the advantages of real-time online, linear monitoring and automatic monitoring.

Description

Technical Field

[0001] The present invention relates to the technical field of water conservancy and hydropower engineering construction technology and its monitoring technology, and particularly relates to a method for distributed optical fiber temperature monitoring of the entire dam section of a small and medium-sized concrete gravity dam. Background Art

[0002] In the technical field of water conservancy and hydropower engineering construction, as an important hydraulic structure, the stability and safety of a concrete gravity dam are directly related to the safe operation of the entire water conservancy project. During the construction process of a concrete gravity dam, temperature control is a crucial link. Since a large amount of hydration heat is generated during the concrete pouring process, if the temperature control is improper, it will lead to too large a temperature difference between the inside and outside of the concrete, and then temperature stress will be generated. When this temperature stress exceeds the crack resistance of the concrete, it will cause the concrete to crack, seriously affecting the durability and safety of the dam.

[0003] Currently, for the temperature monitoring of small and medium-sized concrete gravity dams (specifically referring to dams with a height less than 70m), the vast majority use point thermometers for monitoring. However, this method has obvious deficiencies. First, point thermometers can only provide discrete data points and cannot comprehensively reflect the temperature distribution inside the concrete. Second, the measurement period of point thermometers is relatively short and cannot continuously monitor the temperature changes of the concrete throughout its entire life cycle. Finally, the measurement range of point thermometers is limited and cannot cover all key areas of the entire dam.

[0004] In order to overcome the deficiencies of point thermometers, some concrete gravity dams have begun to attempt to use distributed optical fiber monitoring technology. Distributed optical fiber temperature measurement technology has advantages such as real-time online, linear monitoring, and automatic monitoring, and can achieve continuous and comprehensive monitoring of the temperature inside the concrete. However, most of the existing distributed optical fiber monitoring technologies are only applied to several typical dam sections of the dam and do not achieve full-dam optical fiber coverage. Although this local monitoring method can improve the accuracy and reliability of temperature monitoring to a certain extent, it still cannot comprehensively reflect the temperature distribution of the entire dam.

[0005] For example, a dam internal temperature monitoring system based on distributed optical fiber disclosed in CN206132264U. This system assembles geogrid and optical fiber sensors, lays N optical fiber sensors inside the dam to form temperature sensors, and receives, stores, and analyzes the data collected by the temperature sensors through a data acquisition box. This system realizes the real-time monitoring of the temperature inside the dam to a certain extent and improves the efficiency and accuracy of monitoring.

[0006] However, although the technical solution disclosed in CN206132264U has certain innovation and practicability, there are still some deficiencies. First of all, the layout method of the fiber optic sensors in this system is relatively single, mainly relying on geogrid for laying, and it cannot fully adapt to dam structures of different shapes and sizes, resulting in the layout of monitoring points being not flexible and precise enough. Secondly, there are certain limitations in data acquisition and analysis of this system. For example, the data acquisition frequency, data transmission rate, and data processing algorithms cannot meet the requirements of all application scenarios. In addition, for large or complex dam structures, this system needs to arrange a large number of fiber optic sensors, thus increasing the cost and construction difficulty of the system.

[0007] Especially in alpine and high-altitude areas, due to the harsh and complex environmental conditions, higher requirements are put forward for the temperature monitoring of dams and concrete gravity dams. The daily amplitude and frequency of water levels in these areas are large, posing higher challenges to the timeliness and accuracy of temperature monitoring. If the temperature monitoring is not timely or accurate, there is a serious risk of cracking in the dam concrete, which will pose a serious threat to the safe operation of the dam. However, the technical solution disclosed in CN206132264U has certain deficiencies and limitations when dealing with these special environmental conditions.

[0008] Therefore, it is necessary to study a process and method for distributed fiber optic temperature monitoring of the entire dam section of medium and small concrete gravity dams to achieve real-time, accurate, and comprehensive monitoring of the temperature changes of the dam concrete throughout the entire dam section and the entire life cycle. This can not only provide strong data support for the temperature control measures during the dam construction period but also provide reliable technical guarantees for the safety monitoring during the dam operation period. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for distributed fiber optic temperature monitoring of the entire dam section of medium and small concrete gravity dams, and to solve the defects of the existing technologies in the field of temperature monitoring of medium and small concrete gravity dams. In particular, it aims to solve the problems that the monitoring data of point thermometers are discrete, the measurement period is short, the measurement range is small, and although some dam sections use distributed fiber optic monitoring, the entire dam is not covered, and it cannot meet the more stringent requirements for concrete temperature control in alpine and high-altitude areas.

[0010] To solve the above technical problems, the technical solution adopted by the present invention is: a method for distributed fiber optic temperature monitoring of the entire dam section of medium and small concrete gravity dams, including the following steps: Step1: Arrange the overall layout type of the fiber optic cables for the entire dam, covering all dam sections from the left bank to the right bank along the dam axis direction and the entire range from the bottom to the top of each dam section along the elevation direction; Step 2: Select and arrange different optical fiber layout types according to the deck size, including the "bow type" applicable to large decks, the "W type" applicable to medium decks, and the "variable W type" applicable to small decks; Step 3: Determine the layout type of the optical fiber temperature measurement host, including the determination method of the number of sets of the temperature measurement host and the recommended layout positions.

[0011] In the preferred solution, the small and medium-sized concrete gravity dams in Step 1 refer to dams with a height less than 70m.

[0012] In the preferred solution, the specific overall layout type of the optical fiber for the whole dam in Step 1 is: the optical fiber is buried in a double-strand manner, and the length of the optical fiber required for each dam section is determined according to the following formula: (1) In the formula, is the average optical fiber length of the deck, is the number of decks in each dam section, is the height of the dam section, is the length of the optical fiber lead, is the surplus length of the optical fiber.

[0013] In the preferred solution, the specific "bow type" layout type in Step 2 is that when the deck size is a large deck with a length along the river direction of 60m to 100m, the optical fiber starts from a position at a set distance from the first transverse joint surface and the upstream surface on the upstream surface, is arranged along the dam axis direction to a position at a set distance from the second transverse joint surface, turns 90° downstream and is arranged along the river direction, then turns 90° towards the first transverse joint surface and is arranged, and repeats the turning until the optical fiber is arranged to a position at a set distance from the downstream surface and the first transverse joint surface. The length of the "bow type" optical fiber is calculated as follows: (2) In the formula, is the length along the river direction of the deck, is the width of the transverse joint.

[0014] In the preferred solution, the specific "W type" layout type in Step 2 is that when the deck size is a medium deck with a length along the river direction of 30m to 60m, the optical fiber starts from a position at a set distance from the first transverse joint surface and the upstream surface on the upstream surface, is arranged obliquely at 45° downstream to a position at a set distance from the second transverse joint surface, then turns 90° towards the first transverse joint surface and is arranged, and repeats the turning until the optical fiber is arranged to a position at a set distance from the downstream surface and the first transverse joint surface. The length of the "W type" optical fiber is calculated as follows: (3).

[0015] In the preferred solution, the "variable W-shaped" layout pattern in Step 2 is specifically as follows: when the surface size of the bin is a small bin surface with a length along the river direction of 0 m to 30 m, the optical fiber starts from a position at a set distance from the first transverse joint surface and the upstream surface on the upstream surface, is arranged obliquely downward at 30° to the downstream until reaching a set position from the second transverse joint surface, then turns 60° towards the first transverse joint surface and repeats the turning until the optical fiber is arranged to a position at a set distance from the downstream surface and the first transverse joint surface. The length of the "variable W-shaped" optical fiber The calculation formula is as follows: (4).

[0016] In the preferred solution, the number of sets of temperature measurement mainframes in Step 3 is determined according to the following formula: (5) In the formula, is the number of dam segments of the concrete gravity dam, 5000 represents the length of each roll of optical fiber (which can be adjusted according to needs), represents the available number of channels after a channel expander is equipped for a single temperature measurement mainframe.

[0017] In the preferred solution, the recommended layout positions of the optical fiber temperature measurement mainframes in Step 3 are as follows: before the monitoring gallery is formed, all the temperature measurement mainframes are arranged on the temporary construction platform; after the monitoring gallery is formed, all the temperature measurement mainframes are arranged in the dam body monitoring gallery; if the number of sets of temperature measurement mainframes is an odd number, then all the temperature measurement mainframes are arranged in the same monitoring room, and the monitoring room is set in the middle of the monitoring gallery; if the number of sets of temperature measurement mainframes is an even number, then the temperature measurement mainframes are evenly arranged in 2 monitoring rooms, and the monitoring rooms are symmetrically set at the left and right bank dam segments of the monitoring gallery.

[0018] In the preferred solution, the method further includes Step 4: using the arranged optical fiber and temperature measurement mainframes to conduct temperature monitoring and monitoring the temperature changes of the entire dam segments and the entire life cycle of the concrete dam.

[0019] In the preferred solution, the data of the temperature monitoring in Step 4 is used for adjusting the temperature control measures during the dam construction period and the safety monitoring during the operation period.

[0020] The method for distributed optical fiber temperature monitoring of the entire dam segments of a small and medium-sized concrete gravity dam provided by the present invention has the following beneficial effects: 1. The present invention proposes a brand-new optical fiber coverage solution. The optical fiber covers all the dam segments from the left bank to the right bank along the dam axis direction and all the ranges from the bottom to the top of each dam segment along the elevation direction, ensuring full coverage of the entire dam concrete.

[0021] 2. According to the sizes of different deck surfaces, the present invention adopts three types of optical fiber layout patterns, namely, "bow-shaped", "W-shaped" and "variable W-shaped", which are respectively applicable to large deck surfaces, medium deck surfaces and small deck surfaces, improving the flexibility and accuracy of monitoring.

[0022] 3. The layout and optimization of the optical fiber temperature measurement main unit adopted by the present invention: clarify the layout method of the temperature measurement main unit and the determination method of the number of sets, and provide the recommended layout positions of the temperature measurement main unit to ensure that the temperature measurement main unit can efficiently and accurately receive and process the temperature data transmitted by the optical fiber.

[0023] 4. Compared with the monitoring methods of some dam sections in the past, the present invention can more accurately reflect the overall temperature condition of the dam concrete, realizes the optical fiber coverage of the whole dam section, and greatly improves the comprehensiveness of monitoring.

[0024] 5. For deck surfaces of different sizes, the present invention innovatively proposes three types of optical fiber layout patterns, which not only improve the flexibility and accuracy of monitoring, but also consider the survival rate of optical fiber embedding and the convenience of construction.

[0025] 6. The optimization of the layout method of the system temperature measurement main unit adopted by the present invention, by clarifying the layout method of the temperature measurement main unit and the determination method of the number of sets, provides specific implementation guidance for practical engineering applications, optimizes the layout positions of the temperature measurement main unit, and ensures its stability and safety during the monitoring process.

[0026] 7. The present invention effectively solves the technical problems of the point-type thermometer, such as discrete data volume, short measurement period, small measurement range, etc., improves the accuracy and reliability of temperature monitoring, and provides more powerful data support for concrete temperature control.

[0027] 8. The present invention overcomes the limitations of the limited monitoring effect of distributed optical fiber monitoring used in some dam sections in the past, realizes the real-time monitoring and linear monitoring of the concrete temperature of the whole dam section, and improves the comprehensiveness and accuracy of monitoring.

[0028] 9. The monitoring method of the present invention can meet the strict requirements for concrete temperature control in alpine and high-altitude areas. Through real-time online monitoring and linear monitoring, it can timely discover and adjust temperature control measures to avoid potential safety hazards such as concrete cracking.

[0029] 10. The monitoring method of the present invention provides important help for the adjustment of temperature control measures during the construction period of the dam and the safety monitoring during the operation period. Through the temperature monitoring in the whole life cycle, it lays a solid foundation for the long-term safe service of the dam.

[0030] 11. The present invention provides specific calculation formulas for the optical fiber length, which are used to determine the required optical fiber length under different optical fiber layout patterns of deck surfaces; at the same time, it also provides the calculation formula for the number of sets of the temperature measurement main unit, providing convenience and implementation guidance for practical engineering applications.

[0031] 12. The present invention provides a method for distributed optical fiber temperature monitoring of the entire dam section of a medium - sized and small - sized concrete gravity dam, overcoming many deficiencies of the prior art. It not only improves the comprehensiveness and accuracy of monitoring, but also provides important assistance and support for the adjustment of temperature control measures during the construction period and the safety monitoring during the operation period of the dam. Remarkable achievements have been made in terms of technological innovation, practical application, and effect demonstration, providing new ideas and solutions for the temperature monitoring of concrete dams. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below in conjunction with the drawings and embodiments: Figure 1 Front view of the concrete gravity dam in Embodiment 2 of the present invention (odd - numbered temperature - measuring main machines, red lines represent optical fibers); Figure 2 Front view of the concrete gravity dam in Embodiment 2 of the present invention (even - numbered temperature - measuring main machines, red lines represent optical fibers); Figure 3 Cross - sectional view of the overflow dam section of the concrete gravity dam in Embodiment 2 of the present invention; Figure 4 Cross - sectional view of the non - overflow dam section of the concrete gravity dam in Embodiment 2 of the present invention; Figure 5 "Bow - shaped" optical fiber layout diagram of the large - sized warehouse surface of the present invention; Figure 6 "W - shaped" optical fiber layout diagram of the medium - sized warehouse surface of the present invention; Figure 7 "Variable W - shaped" optical fiber layout diagram of the small - sized warehouse surface of the present invention; In the figure: the first transverse joint surface 1, the upstream surface 2, the second transverse joint surface 3, the downstream surface 4. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The technical solutions in the present invention will be further described below in conjunction with the drawings and embodiments.

[0034] Embodiment 1 As Figures 1 to 7 shown, a method for distributed optical fiber temperature monitoring of the entire dam section of a medium - sized and small - sized concrete gravity dam includes the overall layout type of the optical fiber for the entire dam, the layout type of the optical fiber for different warehouse surfaces, and the layout type of the optical fiber temperature - measuring main machine.

[0035] In this embodiment, the medium and small concrete gravity dam refers to a dam with a height less than 70 m; the overall arrangement type of the optical fibers for the whole dam is: the optical fibers cover all the dam sections from the left bank to the right bank along the dam axis direction and all the ranges from the bottom to the top of each dam section along the elevation direction; the different optical fiber arrangement types for different placement surfaces are: the "bow-shaped" type applicable to large placement surfaces, the "W-shaped" type applicable to medium placement surfaces, and the "variable W-shaped" type applicable to small placement surfaces; the arrangement type of the optical fiber temperature measurement main unit includes the method for determining the number of sets of the main unit and the recommended placement positions.

[0036] Furthermore, the overall arrangement type of the optical fibers for the whole dam is: along the dam axis direction from the left bank to the right bank, one or more rolls of optical fibers are used for each dam section, and the optical fibers are arranged from the bottom to the top of each dam section. If the optical fibers are buried in a double-strand manner, the length of the optical fibers required for each dam section is determined according to formula (1), where is the average optical fiber length of the placement surface, is the number of placement surfaces in each dam section, is the height of the dam section, is the length of the optical fiber lead, is the surplus length of the optical fiber.

[0037] (1) Furthermore, the different optical fiber arrangement types for different placement surfaces are: "Bow-shaped": When the placement surface size is a large placement surface with a length along the river direction of 60 m to 100 m, the Figure 5 "bow-shaped" arrangement type is adopted. The optical fibers start from a position 12 m away from the first transverse joint surface and 22 m away from the upstream surface on the upstream surface, are arranged along the dam axis direction to a position 32 m away from the second transverse joint surface, turn 90° downstream and are arranged along the river direction for about 30 m, then turn 90° towards the first transverse joint surface 1 and are arranged to a position 12 m away from the first transverse joint surface 1, and then turn 90° downstream and are arranged along the river direction for about 30 m, repeating the turning until the optical fibers are arranged to a position 42 m away from the downstream surface and 12 m away from the first transverse joint surface 1.

[0038] If the optical fibers are buried in a double-strand manner, the length of the optical fiber for the "bow-shaped" placement surface is determined according to formula (2), where is the width of the transverse joint, is the length of the placement surface along the river direction, is the length of the optical fiber lead.

[0039] (2) "W-shaped": When the placement surface size is a medium placement surface with a length along the river direction of 30 m to 60 m, the Figure 6The "W-shaped" layout type. The optical fiber starts from a position 12 m away from the first transverse joint surface and 22 m away from the upstream surface on the upstream surface, and is arranged obliquely at 45° downstream to a position 32 m away from the second transverse joint surface. Then it turns 90° towards the first transverse joint surface 1 and is arranged to a position 12 m away from the first step transverse joint surface, and repeats the turning until the optical fiber is arranged to a position 42 m away from the downstream surface and 12 m away from the first transverse joint surface. If the double-strand embedding method is used for the optical fiber, the length of the optical fiber on the "W-shaped" deck is determined according to formula (3), where is the width of the transverse joint, is the longitudinal length of the deck along the river, is the length of the optical fiber lead.

[0040] (3).

[0041] "Variable W-shaped": When the deck size is a small deck with a longitudinal length along the river of 0 m to 30 m, the Figure 7 "Variable W-shaped" layout type is adopted. The optical fiber starts from a position 12 m away from the first transverse joint surface and 22 m away from the upstream surface on the upstream surface, and is arranged obliquely at 30° downstream to a position 32 m away from the second transverse joint surface. Then it turns 60° towards the first transverse joint surface 1 and is arranged to a position 12 m away from the first transverse joint surface, and repeats the turning until the optical fiber is arranged to a position 42 m away from the downstream surface and 12 m away from the first transverse joint surface. If the double-strand embedding method is used for the optical fiber, the length of the optical fiber on the "Variable W-shaped" deck is determined according to formula (4), where is the width of the transverse joint, is the longitudinal length of the deck along the river, is the length of the optical fiber lead.

[0042] (4).

[0043] Furthermore, the number of sets of the temperature measurement main unit in the layout type of the optical fiber temperature measurement main unit is determined according to formula (5), where is the number of dam sections of the concrete gravity dam, is the required optical fiber length for each dam section, 5000 represents the length of each roll of optical fiber is 5000 m (which can be adjusted according to needs), represents the available channels of a single temperature measurement main unit equipped with a channel expander.

[0044] (5) Furthermore, the recommended layout position in the layout type of the optical fiber temperature measurement main unit is as follows: Before the monitoring gallery is formed, all the temperature measurement main units are arranged on the temporary construction platform; after the monitoring gallery is formed, all the temperature measurement main units are arranged in the dam body monitoring gallery. If the number of sets of the temperature measurement main unit If it is a single number, all temperature measurement main units are arranged in the same monitoring room, which can be set in the middle of the monitoring corridor; if the number of sets of temperature measurement main units is an even number, the temperature measurement main units are evenly arranged in 2 monitoring rooms, and the monitoring rooms are symmetrically arranged at the left and right bank dam sections of the monitoring corridor.

[0045] Embodiment 2 In another preferred embodiment, on the basis of the above Embodiment 1, this embodiment provides a method for distributed optical fiber temperature monitoring of the entire dam section of a medium and small concrete gravity dam, including the overall layout type of the whole-dam optical fiber, the optical fiber layout type of different deck surfaces, and the optical fiber temperature measurement main unit layout type.

[0046] The overall layout type of the whole-dam optical fiber is specifically as follows: The optical fiber covers all dam sections (Dam Sections ① - ⑧) along the dam axis direction from the left bank to the right bank and the entire range from the bottom to the top of each dam section along the elevation direction to ensure that the temperature measurement optical fiber fully covers the concrete of the entire dam; The optical fiber adopts a double-strand embedding method, and the average optical fiber length of the deck surface is 110m; the dam section heights are 30m, 40m, 50m, 50m, 50m, 50m, 40m, 30m (Dam Sections ① - ⑧) respectively; the optical fiber lead length is 400m; the optical fiber surplus length of each dam section is 200m; the number of decks of each dam section are 10 decks, 13 decks, 15 decks, 16 decks, 16 decks, 15 decks, 13 decks, 10 decks (Dam Sections ① - ⑧) respectively; the required optical fiber length of each dam section are 3260m, 3969m, 4466m, 4725m, 4760m, 4565m, 4114m, 3421m (Dam Sections ① - ⑧) respectively.

[0047] The optical fiber layout type of different deck surfaces is specifically as follows: The "bow-shaped" for large deck surfaces, the "W-shaped" for medium deck surfaces, and the "variable W-shaped" for small deck surfaces. Thus, personalized optical fiber layout types are adopted for different-sized deck surfaces, and as many optical fibers as possible are laid while ensuring the survival rate of optical fiber embedding and convenient construction, and providing favorable measured data for the subsequent reconstruction of the three-dimensional temperature field of the concrete dam.

[0048] "Bow-shaped": When the deck surface size is a large deck surface with a length of 60m - 100m in the river direction, adopt Figure 5The "bow-shaped" layout type. The optical fiber starts from a position 12m away from the first transverse joint surface and 22m away from the upstream surface on the upstream surface, is arranged along the dam axis direction to a position 32m away from the second transverse joint surface, turns 90° downstream and is arranged along the river direction for about 30m, then turns 90° towards the first transverse joint surface 1 and is arranged to a position 12m away from the first transverse joint surface 1, then turns 90° downstream again and is arranged along the river direction for about 30m, and repeats the turning until the optical fiber is arranged to a position 42m away from the downstream surface and 12m away from the first transverse joint surface. The optical fiber adopts a double-strand embedding method, and the length of the "bow-shaped" deck optical fiber is 154m.

[0049] "W-shaped": When the deck size is a medium-sized deck with a riverward length of 30m to 60m, the Figure 6 adopted "W-shaped" layout type. The optical fiber starts from a position 12m away from the first transverse joint surface and 22m away from the upstream surface on the upstream surface, is arranged obliquely at 45° downstream to a position 32m away from the second transverse joint surface, then turns 90° towards the first transverse joint surface 1 and is arranged to a position 12m away from the first step transverse joint surface 1, and repeats the turning until the optical fiber is arranged to a position 42m away from the downstream surface and 12m away from the first transverse joint surface. The optical fiber adopts a double-strand embedding method, and the length of the "W-shaped" deck optical fiber is 90m.

[0050] "Variable W-shaped": When the deck size is a small deck with a riverward length of 0m to 30m, the Figure 7 adopted "variable W-shaped" layout type. The optical fiber starts from a position 12m away from the first transverse joint surface and 22m away from the upstream surface on the upstream surface, is arranged obliquely at 30° downstream to a position 32m away from the second transverse joint surface, then turns 60° towards the first transverse joint surface 1 and is arranged to a position 12m away from the first transverse joint surface 1, and repeats the turning until the optical fiber is arranged to a position 42m away from the downstream surface and 12m away from the first transverse joint surface. The optical fiber adopts a double-strand embedding method, and the length of the "variable W-shaped" deck optical fiber is 73m.

[0051] The layout type of the optical fiber temperature measurement main unit is specifically as follows: One temperature measurement main unit is equipped with one 8-channel channel expander, and the number of sets of the temperature measurement main unit is 1 set. The layout position of the optical fiber temperature measurement main unit is: Before the monitoring gallery is formed, all the temperature measurement main units are arranged on the temporary construction platform; after the monitoring gallery is formed, all the temperature measurement main units are arranged in the dam body monitoring gallery.

[0052] Embodiment 3 In another preferred embodiment, based on the above-mentioned Embodiment 2, this embodiment is basically the same as Embodiment 2, except that the number of dam sections, height, and surface area of the placement block are different. Specifically, it is applied to another concrete gravity dam with a dam height less than 70m. The dam includes 6 dam sections, the height of each dam section is not completely the same, and the surface area of the placement block also varies. According to specific circumstances, the optical fiber lengths required for each dam section are calculated respectively, and corresponding optical fiber layout types and temperature measurement host layout types are adopted.

[0053] Embodiment 4 In another preferred embodiment, based on the above-mentioned Embodiment 2, this embodiment is similar to Embodiment 2 and Embodiment 3, but it is for a concrete gravity dam located in an alpine and high-altitude area. The dam not only has a dam height less than 70m, but also due to environmental factors, the requirements for concrete temperature control are more stringent. Therefore, in this embodiment, more attention is paid to the density of optical fiber layout and the configuration of temperature measurement hosts to ensure comprehensive and accurate monitoring of concrete temperature. At the same time, considering the climatic characteristics of alpine and high-altitude areas, the protection measures for optical fibers and temperature measurement hosts are also strengthened.

[0054] Through the detailed description of the above four embodiments, it can be seen that the method for distributed optical fiber temperature monitoring of the entire dam section of small and medium-sized concrete gravity dams provided by the present invention has wide applicability and practicability. It not only covers concrete gravity dams with different dam heights, different numbers of dam sections, and different surface areas of the placement block, but also takes into account the special environmental requirements of alpine and high-altitude areas. The present invention realizes the temperature monitoring of the entire dam section and the entire life cycle of the concrete dam through comprehensive and accurate optical fiber layout and temperature measurement host configuration, providing important assistance for the adjustment of temperature control measures during the construction period and the safety monitoring during the operation period of the concrete dam.

[0055] In a preferred solution, the overall layout type of the optical fiber for the entire dam in Step 1 is specifically that the optical fiber is buried in a double-strand manner, and the optical fiber lengths required for each dam section Formula (1); the above settings ensure the stability and reliability of the optical fiber monitoring system; among them, Formula (1) comprehensively considers factors such as dam body size, deformation monitoring requirements, and optical fiber loss, providing a scientific basis for the accurate calculation of the optical fiber length.

[0056] In a preferred solution, the "bow-shaped" layout type in Step 2 is specifically that when the surface area of the placement block is a large placement block with a length in the river direction of 60m to 100m, the optical fiber starts from a position at a set distance from the first transverse joint surface 1 and the upstream surface 2 on the upstream surface, is arranged along the dam axis direction to a position at a set distance from the second transverse joint surface 3, turns 90° downstream and is arranged along the river direction, then turns 90° towards the first transverse joint surface 1 and is arranged, and repeats the turning until the optical fiber is arranged to a position at a set distance from the downstream surface 4 and the first transverse joint surface 1. The "bow-shaped" optical fiber length It is determined according to formula (2); with the above settings, it can ensure the uniform distribution of the optical fiber within the deck surface and effectively monitor the deformation of the dam body. At the same time, the "bow-shaped" layout can flexibly adapt to different deck surface sizes, improve the monitoring efficiency and accuracy, and provide a strong guarantee for the project safety.

[0057] In the preferred solution, the "W-shaped" layout in Step 2 is specifically as follows: when the deck surface size is a medium-sized deck surface with a longitudinal length along the river of 30 m to 60 m, the optical fiber starts from a position at a set distance from the first transverse joint surface 1 and the upstream surface 2 on the upstream surface, and is arranged obliquely downward at 45° to a position at a set distance from the second transverse joint surface 3 downstream, and then turns 90° to be arranged towards the first transverse joint surface 1, and repeats the turning until the optical fiber is arranged to a position at a set distance from the downstream surface 4 and the first transverse joint surface 1. The length of the "W-shaped" optical fiber It is determined according to formula (3); with the above settings, it can ensure that the layout of the optical fiber within the deck surface is both economical and efficient, can fully cover the monitoring area, avoid the signal attenuation problem caused by too long optical fiber, and is convenient for later maintenance and management, providing a strong guarantee for the safety monitoring of the dam.

[0058] In the preferred solution, the "variable W-shaped" layout in Step 2 is specifically as follows: when the deck surface size is a small deck surface with a longitudinal length along the river of 0 m to 30 m, the optical fiber starts from a position at a set distance from the first transverse joint surface 1 and the upstream surface 2 on the upstream surface, and is arranged obliquely downward at 30° to a position at a set distance from the second transverse joint surface 3 downstream, and then turns 60° to be arranged towards the first transverse joint surface 1, and repeats the turning until the optical fiber is arranged to a position at a set distance from the downstream surface 4 and the first transverse joint surface 1. The length of the "variable W-shaped" optical fiber It is determined according to formula (4); with the above settings, it can effectively avoid the excessive bending or stretching of the optical fiber caused by the change of the deck surface size, ensure the accuracy of the monitoring data; at the same time, the "variable W-shaped" layout can also improve the flexibility and adaptability of the optical fiber layout, and meet the monitoring requirements under different deck surface sizes.

[0059] In the preferred solution, the recommended layout positions of the optical fiber temperature measurement main units in Step 3 are as follows: before the monitoring gallery is formed, all the temperature measurement main units are arranged on the temporary construction platform; after the monitoring gallery is formed, all the temperature measurement main units are arranged in the dam body monitoring gallery; the number of sets of the temperature measurement main units is an odd number, then all the temperature measurement main units are arranged in the same monitoring room, and the monitoring room is set in the middle of the monitoring gallery; the number of sets of the temperature measurement main units is an even number, then the temperature measurement main units are evenly arranged in 2 monitoring rooms, and the monitoring rooms are symmetrically set at the left and right bank dam sections of the monitoring gallery; with the above settings, it can ensure that the temperature measurement data is fully covered and easy to maintain, and at the same time is convenient for centralized management and analysis of the temperature measurement data, improve the monitoring efficiency and accuracy, and provide a reliable basis for the safety assessment of the dam body.

[0060] In a preferred embodiment, the method further includes Step 4: using the arranged optical fibers and temperature measurement host to conduct temperature monitoring, and monitoring the temperature changes of the entire dam section and the entire life cycle of the concrete dam; the above settings can realize the real-time collection and analysis of the temperature data of the concrete dam, timely detect abnormal temperature changes, provide reliable data support for the safe operation of the concrete dam, and effectively prevent problems such as cracks caused by temperature stress.

[0061] In a preferred embodiment, the temperature monitoring data in Step 4 is used for the adjustment of temperature control measures during the dam construction period and the safety monitoring during the operation period; the above settings ensure that the temperature data can be effectively used to guide the adjustment of temperature control strategies during construction and to conduct safety risk assessments during the dam operation stage, thereby enhancing the stability and durability of the overall dam structure.

[0062] In summary, the method for distributed optical fiber temperature monitoring of the entire dam section of small and medium-sized concrete gravity dams provided by the present invention effectively solves many defects of the prior art in the field of temperature monitoring of small and medium-sized concrete gravity dams, such as the discrete amount of monitoring data of point thermometers, short measurement periods, small measurement ranges, and the fact that although some dam sections use distributed optical fiber monitoring, they do not achieve full-dam coverage, which cannot meet the more stringent requirements for concrete temperature control in alpine and high-altitude areas. This solution innovatively proposes a method for distributed optical fiber temperature monitoring of the entire dam section for small and medium-sized dam bodies, which is not common in previous monitoring technologies. At the same time, according to the different sizes of the placement surfaces, the solution flexibly designs three optical fiber arrangement types, namely "bow-shaped", "W-shaped", and "variable W-shaped", to meet the monitoring requirements of different placement surfaces. In addition, the solution also clarifies the arrangement method of the temperature measurement host and provides a method for calculating the number of sets of temperature measurement hosts based on the number of dam sections and the optical fiber length, providing specific implementation guidance for practical engineering applications. By customizing the optical fiber arrangement type, the solution not only ensures the comprehensiveness of monitoring but also improves the accuracy and efficiency of monitoring. The solution also proposes a formula for calculating the optical fiber length based on the placement surface size and the optical fiber arrangement type, providing a specific calculation basis for engineering practice and improving the economy and practicability of the monitoring system. Based on the comprehensive consideration of various factors such as the dam height, the number of dam sections, the placement surface size, and environmental factors (such as alpine and high-altitude areas), the monitoring method of the present invention provides technical support for the temperature monitoring of the entire dam section and the entire life cycle of the concrete dam, helps to ensure the safe operation of the dam, and provides new ideas and methods for the temperature monitoring of small and medium-sized concrete gravity dams.

Claims

1. A method for distributed optical fiber temperature monitoring of the entire dam section of a small or medium-sized concrete gravity dam, characterized in that: The following steps are involved: Step 1: Arrange the overall layout of the optical fiber of the whole dam, covering all dam sections from the left bank to the right bank along the dam axis and the entire range from the bottom to the top of each dam section along the elevation direction; Step 2: According to the size of the warehouse surface, select and arrange different warehouse surface optical fiber layout types, including "bow type" suitable for large warehouse surface, "W type" suitable for medium warehouse surface, and "varied W type" suitable for small warehouse surface; Step 3: Determine the layout type of the fiber optic temperature measurement host, including the method for determining the number of temperature measurement host sets and the recommended layout location.

2. The method for distributed optical fiber temperature monitoring of the entire dam section of a small and medium-sized concrete gravity dam according to claim 1 is characterized in that: The small and medium-sized concrete gravity dams in Step 1 refer to dams with a height of less than 70m.

3. The method for distributed optical fiber temperature monitoring of the entire dam section of a small and medium-sized concrete gravity dam according to claim 2 is characterized in that: The overall layout of the optical fiber in the whole dam in Step 1 is specifically as follows: the optical fiber is buried in double strands, and the required optical fiber length for each dam section is Determined according to the following formula: （1）； In the formula, is the average optical fiber length on the warehouse surface, is the number of bins in each dam section, The dam section is high, is the fiber lead length, The remaining length of the optical fiber.

4. The method for distributed optical fiber temperature monitoring of the entire dam section of a small and medium-sized concrete gravity dam according to claim 3 is characterized by: The "bow-shaped" arrangement in Step 2 is specifically as follows: when the size of the warehouse surface is a large warehouse surface with a length of 60m to 100m in the downstream direction, the optical fiber starts from the upstream surface at a position at a set distance from the first transverse seam surface (1) and the upstream surface (2), is arranged along the dam axis to a position at a set distance from the second transverse seam surface (3), turns 90 degrees downstream and is arranged in the downstream direction, then turns 90 degrees to the first transverse seam surface (1), and repeats the turns until the optical fiber is arranged at a position at a set distance from the downstream surface (4) and the first transverse seam surface (1). The length of the "bow-shaped" optical fiber is The calculation formula is as follows: （2）； In the formula, is the length of the warehouse along the river, is the width of the horizontal seam.

5. The method for distributed optical fiber temperature monitoring of the entire dam section of a small or medium-sized concrete gravity dam according to claim 4 is characterized in that: The "W-shaped" arrangement in Step 2 is specifically that, when the size of the warehouse surface is a medium warehouse surface with a length of 30m to 60m along the river, the optical fiber starts from the upstream surface at a position at a set distance from the first transverse seam surface (1) and the upstream surface (2), is arranged downstream at an angle of 45° to a position at a set distance from the second transverse seam surface (3), then turns 90° to the first transverse seam surface (1), and repeats the turns until the optical fiber is arranged at a position at a set distance from the downstream surface (4) and the first transverse seam surface (1). The length of the "W-shaped" optical fiber is The calculation formula is as follows: （3）。 6. The method for distributed optical fiber temperature monitoring of the entire dam section of a small or medium-sized concrete gravity dam according to claim 5 is characterized in that: The "variable W-shaped" arrangement in Step 2 is specifically as follows: when the size of the warehouse surface is a small warehouse surface with a length of 0m to 30m in the downstream direction, the optical fiber starts from the upstream surface at a position at a set distance from the first transverse seam surface (1) and the upstream surface (2), is arranged downstream at an angle of 30° to a position at a set distance from the second transverse seam surface (3), then turns 60° to the first transverse seam surface (1), and repeats the turning until the optical fiber is arranged at a position at a set distance from the downstream surface (1) and the first transverse seam surface (1). The length of the "variable W-shaped" optical fiber is The calculation formula is as follows: （4）。 7. The method for distributed optical fiber temperature monitoring of the entire dam section of a small or medium-sized concrete gravity dam according to claim 6 is characterized by: The number of temperature measurement host units in Step 3 Determined according to the following formula: （5）； In the formula, is the number of sections of the concrete gravity dam, Indicates the number of available channels after a single temperature measurement host is equipped with a channel expander.

8. The method for distributed optical fiber temperature monitoring of the entire dam section of a small and medium-sized concrete gravity dam according to claim 7 is characterized in that: The recommended layout of the optical fiber temperature measurement host in Step 3 is as follows: before the monitoring corridor is formed, all temperature measurement hosts are arranged on a temporary construction platform; after the monitoring corridor is formed, all temperature measurement hosts are arranged in the dam body monitoring corridor; the number of temperature measurement host sets is If it is an odd number, all temperature measuring hosts are arranged in the same monitoring room, and the monitoring room is set in the middle of the monitoring corridor; the number of temperature measuring hosts If it is an even number, the temperature measuring hosts will be evenly arranged in two monitoring rooms, and the monitoring rooms will be symmetrically set at the left and right bank sections of the monitoring corridor.

9. The method for distributed optical fiber temperature monitoring of the entire dam section of a small or medium-sized concrete gravity dam according to any one of claims 1 to 8, characterized in that: The method also includes Step 4: utilizing the arranged optical fiber and temperature measuring host to perform temperature monitoring to monitor the temperature changes of the entire dam section and the entire life cycle of the concrete dam.

10. The method for distributed optical fiber temperature monitoring of the entire dam section of a small or medium-sized concrete gravity dam according to claim 9, characterized in that: The temperature monitoring data in Step 4 is used for adjusting the temperature control measures during the dam construction period and for safety monitoring during the operation period.

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