A real-time measurement system and construction measurement method for the inner diameter of NPR anchor cables in high slope protection engineering

Abstract

This invention provides a real-time measurement system and construction measurement method for the inner diameter of NPR anchor cables in high slope protection engineering, relating to the field of high slope protection engineering. The system and method include a constant resistance body installed inside a constant resistance sleeve of the anchor cable, and a measuring component for measuring the inner diameter of the sleeve. The constant resistance body contains multiple rollers and sensors, with the rollers contacting the sleeve. In dynamic conditions, the sensors and rollers work together to control the synchronous movement of the measuring component, capturing real-time changes in the inner diameter during displacement. In static conditions, a spiral guide rail drives a beam scan to acquire full-area data. The movable measuring component reduces the amount of hardware required. Automatic scanning is achieved using pneumatic drive and a spiral track, eliminating the need for a complex power system and reducing equipment costs and energy consumption.

Description

Technical Field

[0001] This invention relates to the field of high slope protection engineering, specifically to a real-time measurement system and construction measurement method for the inner diameter of NPR anchor cables in high slope protection engineering. Background Technology

[0002] High slope protection engineering is a comprehensive measure to reinforce and protect the stability of slopes with complex geological conditions, steep slopes, or potential landslides and collapses through engineering techniques. Its core objective is to prevent slope instability that could trigger geological disasters such as landslides and rockfalls, ensuring the safety of surrounding traffic, buildings, personnel, and the stability of the ecological environment. NPR anchor cables, or constant resistance large deformation anchor cables, are a new type of geotechnical engineering reinforcement component with "constant resistance and large deformation" characteristics. In high slope protection engineering, they are mainly used to address complex slope environments with high ground stress, strong earthquakes, and significant creep deformation. Their core function is to solve the problems of traditional anchor cables being prone to breakage and insufficient impact resistance under large deformation loads through their unique mechanical properties, significantly improving slope stability and disaster prevention capabilities. Generally, the measuring device mainly measures the change in the inner diameter of the anchor cable sleeve at the installation location; from this perspective, it measures only a part of the NPR anchor cable. However, through reasonable design and arrangement of the measuring device, it can reflect the stress and deformation of different parts of the entire anchor cable to a certain extent. For example, by installing multiple measuring devices at different key locations on the anchor cable, such as the anchoring section and the free section, the changes in the inner diameter of different parts of the anchor cable can be monitored in real time, thereby gaining a more comprehensive understanding of the working status of the anchor cable.

[0003] In existing technologies, the principle of inner diameter measuring devices, in conjunction with constant resistance bodies and constant resistance sleeves, for measurement is typically based on mechanical transmission, displacement sensing, or pressure feedback mechanisms. Through the relative motion or force changes between the constant resistance body and the constant resistance sleeve, the inner diameter dimension is converted into a measurable physical signal (such as displacement, stress, or electrical signal). The constant resistance body is usually a rigid measuring probe that contacts the surface of the inner diameter being measured, generating radial displacement as the inner diameter changes. The transmission mechanism inside the constant resistance sleeve converts the radial displacement of the constant resistance body into axial displacement or rotational motion, which is then transmitted to the measuring sensor, thereby achieving the measurement of the inner diameter of the constant resistance sleeve. The anchor cable is located inside the constant resistance sleeve. These are impact-resistant structures used on high slopes. Changes in their inner diameter can reflect the deformation of the casing under stress. Traditional measuring devices, such as contact measurement, use mechanical probes to directly contact the inner wall of the casing and convert the inner diameter change into an electrical signal through a displacement sensor. Non-contact measurement uses laser ranging or ultrasonic principles to calculate the inner diameter by transmitting and receiving reflected signals. Regardless of whether it is contact or non-contact, the core of traditional devices is local measurement at a single point or a limited number of points. It is necessary to obtain inner diameter data at different locations by moving the probe or the device itself. When the anchor cable is under stress, it may simultaneously experience axial tension and radial contraction, i.e., the NPR effect.

[0004] Traditional anchor cable inner diameter measurement systems generally use fixed-installation sensors, fixing the sensors to a single section of the constant resistance sleeve, which can only obtain the inner diameter data at that location. However, under actual working conditions, the constant resistance sleeve is subjected to geological stress, impact loads, etc., and its deformation is often unevenly distributed along the axial direction, which may result in local bulging and shrinkage. Since it is difficult to change the sensor position using the traditional fixed installation method, if it is necessary to detect the inner diameter along the entire length of the sleeve, a large number of sensors need to be added, which leads to increased costs. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a real-time measurement system and construction measurement method for the inner diameter of NPR anchor cables in high slope protection engineering. This solves the problem that a single sensor can only measure a single cross-section of the constant resistance sleeve, and if it is necessary to detect the inner diameter over the entire length of the sleeve, a larger number of sensors are required, resulting in higher costs.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a real-time measurement system and construction measurement method for the inner diameter of NPR anchor cables in high slope protection engineering, comprising a constant resistance body installed inside a constant resistance sleeve of the anchor cable, and a measuring component for measuring the inner diameter of the constant resistance sleeve of the anchor cable. The constant resistance body is provided with multiple rollers and sensors. The rollers are in contact with the constant resistance sleeve. An air tube assembly is installed at the constant resistance body. The air tube assembly is used to inject gas. A solenoid valve is installed at one end of the air tube assembly. A spiral guide rail is provided on its outer side, and a stopper rod is provided on its inner side. The measuring component is fixed relative to the stopper rod.

[0007] When multiple rollers move axially along the constant resistance sleeve along with the constant resistance body, the sensor outputs an electrical signal to control the solenoid valve to close, and the measuring component moves synchronously with the constant resistance body to collect the inner diameter data of the corresponding position of the constant resistance sleeve in real time.

[0008] When the constant resistance body does not move, the solenoid valve opens, and the plug rod in the air tube assembly moves axially under air pressure. At the same time, the spiral guide rail restricts the beam emitted by the measuring component to scan a spiral trajectory along the inner wall of the constant resistance sleeve to obtain the inner diameter distribution data within the entire stroke range.

[0009] Preferably, the roller is rotatably connected to the constant resistance body via a rotating shaft. The inner ring of the roller is made of hard material, and its outer ring is made of soft material. The outer ring is pressed against the inner wall of the constant resistance sleeve and undergoes elastic deformation.

[0010] Preferably, the constant resistance body has an internal mounting groove, the roller and the sensor are located in the mounting groove, and the sensor is fixed relative to the mounting groove.

[0011] Preferably, the electrical signals from the multiple sensors are processed in series and then connected to the control terminal of the solenoid valve. The solenoid valve is closed only when all sensors output valid electrical signals.

[0012] Preferably, the tracheal assembly includes a connected internal tube and an extension tube, the internal tube being fixed in the constant resistance body, and the extension tube being fixed to the small-diameter end of the constant resistance body and providing support for the measuring assembly.

[0013] Preferably, the plunger includes a piston, a plug rod, and a connecting cylinder. The piston is slidably connected to the extension tube. A mounting base is fixedly installed on one side of the measuring assembly. The piston, plug rod, mounting base, and connecting cylinder are fixed in sequence. A guide block is fixedly installed inside the connecting cylinder. The guide block is located inside the spiral guide rail and is used to move along the spiral guide rail.

[0014] Preferably, the outer ring of the roller is fixedly connected with a plurality of elastic rubber protrusions arranged in a circle.

[0015] A construction measurement method for a real-time measurement system for the inner diameter of NPR anchor cables in high slope protection engineering also includes the following steps.

[0016] S1: The constant resistance body is fixedly connected to the anchor cable steel core through four mounting holes and placed into the constant resistance sleeve as a whole to ensure that the outer ring of the roller is in elastic contact with the inner wall of the constant resistance sleeve.

[0017] S2: Connect the air tube assembly to the air source, so that the solenoid valve is in the normally open state, inject gas into the air tube assembly, fix the measuring component and the plug rod, and embed the guide block into the spiral guide rail;

[0018] S3: When the constant resistance body moves along the axial direction of the constant resistance sleeve under the action of external force, multiple rollers rotate synchronously, triggering all sensors to output electrical signals. After series logic processing, the solenoid valve closes the air path, and the measuring component moves synchronously with the constant resistance body, collecting the inner diameter data on the moving path in real time. The data acquisition module synchronously records the measured value of the displacement sensor and the position coordinates of the constant resistance body to construct a dynamic inner diameter change curve.

[0019] S4: When the constant resistance body stops moving, the solenoid valve automatically opens, the plug rod moves axially under air pressure, and the guide block moves along the spiral guide rail, forcing the beam emitted by the measuring component to perform a spiral trajectory scan along the inner wall of the constant resistance sleeve to obtain the inner diameter distribution data within the entire stroke range. By matching the angular velocity of the spiral scan with the linear velocity of the plug rod, the three-dimensional contour reconstruction of the inner wall of the constant resistance sleeve is realized.

[0020] S5: The continuous point data of dynamic measurement is spatiotemporally registered with the spiral trajectory data of static scanning. By comparing the inner diameter distribution at different time points, the local bulging and shrinkage deformation characteristics of the constant resistance sleeve are identified. Based on the preset threshold, deformation early warning signals are automatically generated to guide the maintenance decisions of slope protection projects.

[0021] Compared with existing technologies, this invention has the following advantages: Through a dual-mode approach of dynamic synchronous measurement and static spiral scanning, continuous monitoring of the inner diameter of the constant resistance sleeve throughout its entire stroke is achieved. Under dynamic conditions, the sensor and roller work together to control the synchronous movement of the measuring components, capturing the inner diameter changes during the displacement process in real time. In static conditions, the spiral guide rail drives the beam scanning to acquire full-range data, effectively avoiding the omission of local bulging and contraction deformation features and comprehensively improving measurement integrity. Compared with traditional methods that require a large number of sensors to cover the entire sleeve, the movable measuring components reduce the number of hardware components. Automatic scanning is achieved using pneumatic drive and a spiral track, eliminating the need for an additional complex power system and reducing equipment costs and energy consumption. Attached Figure Description

[0022] Figure 1 This is a front view of the constant resistance body and extension tube of the present invention;

[0023] Figure 2 This is a side view of the constant resistance body and extension tube of the present invention;

[0024] Figure 3 This is a schematic diagram of the internal structure of the constant resistance sleeve of the present invention;

[0025] Figure 4 This is a cross-sectional view of the front view of the constant resistance body of the present invention;

[0026] Figure 5 This is a sectional view of the front view of the plug rod of the present invention;

[0027] Figure 6 This is a schematic diagram of the structure of the spiral guide rail of the present invention;

[0028] Figure 7 This is a cross-sectional view of the side view of the constant resistance body of the present invention;

[0029] Figure 8 This is a cross-sectional view of the side view of the roller and the elastic rubber protrusion of the present invention.

[0030] The components include: 1. Constant resistance sleeve; 2. Constant resistance body; 3. Measuring component; 4. Roller; 5. Sensor; 6. Air tube assembly; 601. Internal tube; 602. Extension tube; 7. Solenoid valve; 8. Helical guide rail; 9. Plug rod; 901. Piston; 902. Insert rod; 903. Connecting cylinder; 904. Mounting base; 10. Mounting groove; 11. Elastic rubber protrusion; 12. Guide block. Detailed Implementation

[0031] like Figures 1-8As shown, a real-time measurement system and construction measurement method for the inner diameter of NPR anchor cables in high slope protection engineering includes a constant resistance body 2 installed inside a constant resistance sleeve 1 for anchor cables, and a measuring component 3 for measuring the inner diameter of the constant resistance sleeve 1. Four mounting holes inside the constant resistance body 2 are used to install the anchor cable steel core. Multiple rollers 4 and sensors 5 are provided inside the constant resistance body 2. The rollers 4 are arranged circumferentially and are rotatably connected to the constant resistance body 2 via rotating shafts. The inner ring of the roller 4 is made of a hard material, and its outer ring is made of a soft material, with the outer ring pressed against the constant resistance sleeve 1. At the wall, elastic deformation occurs. The constant resistance body 2 has an internal mounting groove 10. The roller 4 and sensor 5 are located in the mounting groove 10. The sensor 5 is fixed relative to the mounting groove 10. The roller 4 is in contact with the constant resistance sleeve 1. An air tube assembly 6 is installed at the constant resistance body 2. The air tube assembly 6 includes a connected internal tube 601 and an extension tube 602. The internal tube 601 is fixed in the constant resistance body 2, and the extension tube 602 is fixed to the small diameter end of the constant resistance body 2 and provides support for the measuring component 3. Several circumferentially arranged elastic rubbers are fixedly connected to the outer ring of the roller 4. The convex strip 11, on the one hand, increases the resistance between the outer ring of the roller 4 and the constant resistance sleeve 1, which is conducive to the effective rotation of the roller 4 and prevents slippage and signal loss. On the other hand, the elastic deformation of the convex strip can amplify the small rotation of the roller 4, which reduces the detection threshold of the sensor 5 compared to the smooth roller 4, and improves the trigger sensitivity of the sensor 5. This can effectively capture the initial deformation signal when the constant resistance body 2 moves slowly. The air tube assembly 6 is used to inject gas. One end of it is equipped with a solenoid valve 7. A spiral guide rail 8 is provided on its outer side and a stopper rod 9 is provided on its inner side. The measuring assembly 3 is fixed relative to the stopper rod 9. The electrical signals of multiple sensors 5 are connected to the control terminal of the solenoid valve 7 after being processed in series logic. The solenoid valve 7 is controlled to close only when all sensors 5 output valid electrical signals. A logic control module, such as a relay group or a PLC controller, is set at the front end of the solenoid valve 7. The electrical signals of multiple sensors 5 are processed in series logic. The default state of the solenoid valve 7 is normally open, that is, the air path of the air tube assembly 6 is open when the power is off. When all sensors 5 are triggered, the solenoid valve 7 switches to the closed state, and the air path of the air tube assembly 6 is cut off.

[0032] When multiple rollers 4 move axially along the constant resistance sleeve 1 with the constant resistance body 2, the sensor 5 outputs an electrical signal to control the solenoid valve 7 to close, and the measuring component 3 moves synchronously with the constant resistance body 2 to collect the inner diameter data of the corresponding position of the constant resistance sleeve 1 in real time.

[0033] When the constant resistance body 2 does not move, the solenoid valve 7 opens, and the plug rod 9 in the air tube assembly 6 moves axially under air pressure. At the same time, the spiral guide rail 8 restricts the beam emitted by the measuring assembly 3 to scan a spiral trajectory along the inner wall of the constant resistance sleeve 1 to obtain the inner diameter distribution data within the entire stroke range. The plug rod 9 includes a piston 901, an insert rod 902, and a connecting cylinder 903. The piston 901 is slidably connected to the extension tube 602. A mounting base 904 is fixedly installed on one side of the measuring assembly 3. The piston 901, insert rod 902, mounting base 904, and connecting cylinder 903 are fixed in sequence. A guide block 12 is fixedly installed inside the connecting cylinder 903. The guide block 12 is located inside the spiral guide rail 8 and is used to move along the spiral guide rail 8.

[0034] A construction measurement method for a real-time measurement system for the inner diameter of NPR anchor cables in high slope protection engineering, further comprising the following steps:

[0035] S1: The constant resistance body 2 is fixedly connected to the anchor cable steel core through four mounting holes and inserted into the constant resistance sleeve 1 as a whole, ensuring that the outer ring of the roller 4 is in elastic contact with the inner wall of the constant resistance sleeve 1.

[0036] S2: Connect the air tube assembly 6 to the air source, so that the solenoid valve 7 is normally open, inject gas into the air tube assembly 6, fix the measuring component 3 and the plug rod 9, and embed the guide block 12 into the spiral guide rail 8.

[0037] S3: When the constant resistance body 2 moves along the axial direction of the constant resistance sleeve 1 under the action of external force, multiple rollers 4 rotate synchronously, triggering all sensors 5 to output electrical signals. After series logic processing, the solenoid valve 7 closes the air path, and the measuring component 3 moves synchronously with the constant resistance body 2, collecting the inner diameter data on the moving path in real time. The data acquisition module synchronously records the measured value of the displacement sensor 5 and the position coordinates of the constant resistance body 2 to construct a dynamic inner diameter change curve.

[0038] S4: When the constant resistance body 2 stops moving, the solenoid valve 7 automatically opens, the plug rod 9 moves axially under air pressure, and the guide block 12 moves along the spiral guide rail 8, forcing the beam emitted by the measuring component 3 to perform a spiral trajectory scan along the inner wall of the constant resistance sleeve 1, and obtain the inner diameter distribution data within the entire stroke range. By matching the angular velocity of the spiral scan with the linear velocity of the plug rod 9, the three-dimensional contour reconstruction of the inner wall of the constant resistance sleeve 1 is realized.

[0039] S5: The continuous point data of dynamic measurement is spatiotemporally registered with the spiral trajectory data of static scanning. By comparing the inner diameter distribution at different time points, the local bulging and contraction deformation characteristics of the constant resistance sleeve 1 are identified. Based on a preset threshold, a deformation early warning signal is automatically generated to guide the maintenance decision-making of slope protection projects.

[0040] In use, the constant resistance body 2 is securely connected to the anchor cable steel core through the four internal mounting holes. Then, the two are installed as a whole into the constant resistance sleeve 1. The multiple rollers 4 arranged circumferentially inside the constant resistance body 2 are in close contact with the inner wall of the constant resistance sleeve 1. The outer ring of the rollers 4 is made of elastic rubber or soft material, which undergoes elastic deformation upon contact, ensuring good contact while avoiding damage to the inner wall of the sleeve. Next, the air pipe assembly 6 is connected to the air source, such as an external air pump. At this time, the solenoid valve 7 is in the default normally open state, and gas is injected into the air pipe assembly 6. Then, the measuring component 3 is fixed to the mounting seat 904 on the plug rod 9, and the slider in the extension tube 602 is ensured to be located in the spiral guide rail 8 to complete the system installation and preparation work, and to prepare for subsequent measurements.

[0041] Next, when the NPR anchor cable is subjected to geological stress and impact load from the high slope soil and rock, the constant resistance body 2 moves axially along the constant resistance sleeve 1. During the movement of the constant resistance body 2, multiple rollers 4 in contact with it rotate under the action of friction on the inner wall of the sleeve. Each roller 4 is equipped with a corresponding sensor 5. When the roller 4 rotates, it triggers the sensor 5 to output an electrical signal. The electrical signals output by multiple sensors 5 are transmitted to the logic control module at the front end of the solenoid valve 7, such as a relay group or a PLC controller, for series logic processing. Only when all sensors 5 output valid electrical signals will the valve be activated. Only when the logic control module sends a control signal to the solenoid valve 7 will the solenoid valve 7 close the air passage. After the solenoid valve 7 is closed, the air pressure in the air tube assembly 6 cannot push the stopper rod 9 to move. At this time, the measuring component 3 and the constant resistance body 2 move synchronously. The displacement sensor 5 built into the measuring component 3 collects the inner diameter data of the corresponding position of the constant resistance sleeve 1 in real time. At the same time, the data acquisition module on the air tube assembly 6 records the measured value of the displacement sensor 5 and the position coordinates of the constant resistance body 2. By continuously collecting data, a dynamic inner diameter change curve is constructed, thereby realizing real-time monitoring of the constant resistance sleeve 1 during the dynamic displacement process.

[0042] Next, when the constant resistance body 2 stops moving, that is, when the multiple rollers 4 no longer rotate, the multiple sensors 5 have no electrical signal output or cannot meet the condition that all sensors 5 output valid electrical signals; at this time, the logic control module no longer sends a closing signal to the solenoid valve 7, the solenoid valve 7 automatically opens, the air passage in the air tube assembly 6 is opened, and under the drive of air pressure, the stopper rod 9 moves axially. Since the slider on the stopper rod 9 is located in the spiral guide rail 8, the spiral guide rail 8 restricts the movement trajectory of the slider, forcing the stopper rod 9 to generate rotational motion while moving axially. The measuring component 3, which is fixed relative to the stopper rod 9, also moves accordingly. The beam emitted by the measuring component 3 scans along the inner wall of the constant resistance sleeve 1 in a spiral trajectory, thereby realizing the measurement of the constant resistance sleeve. The system performs a complete scan of the inner wall of pipe 1 throughout its entire stroke to obtain detailed inner diameter distribution data, thereby enabling the reconstruction of the three-dimensional contour of the inner wall of the constant resistance sleeve 1. This compensates for potential measurement blind spots during dynamic measurements. It should be noted that the system registers the continuous point data obtained from dynamic measurements with the spiral trajectory data obtained from static scanning, integrating them into a complete dataset of the inner diameter of the constant resistance sleeve 1. By comparing the inner diameter distribution data at different time points, the system can accurately identify the local bulging and contraction deformation characteristics of the constant resistance sleeve 1. The system presets a deformation threshold, and when the analyzed data exceeds this threshold, it automatically generates a deformation warning signal, providing a scientific basis for maintenance decisions in high slope protection projects, timely detection of potential risks, and ensuring slope safety.

[0043] Finally, it should be noted that, addressing the issues of fixed sensor 5 and incomplete data in traditional anchor cable inner diameter measurement systems, this system achieves continuous monitoring of the inner diameter of the constant resistance sleeve 1 throughout its entire stroke through a dual-mode approach of dynamic synchronous measurement and static spiral scanning. Under dynamic conditions, sensor 5 and roller 4 work together to control the synchronous movement of the measuring component 3, capturing the inner diameter changes during displacement in real time. In static conditions, the spiral guide rail 8 drives the beam scanning to acquire full-range data, effectively avoiding the omission of local bulging and contraction deformation features and comprehensively improving measurement integrity. Compared to traditional methods that require a large number of sensors 5 to cover the entire sleeve, this system reduces the number of hardware components through the movable measuring component 3. Automatic scanning is achieved using pneumatic drive and a spiral track, eliminating the need for an additional complex power system and reducing equipment costs and energy consumption.

[0044] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A real-time measurement system for the inner diameter of NPR anchor cables in high slope protection engineering, comprising a constant resistance body installed inside a constant resistance sleeve of the anchor cable, and a measuring component for measuring the inner diameter of the constant resistance sleeve of the anchor cable, characterized in that: The constant resistance body is equipped with multiple rollers and sensors. The rollers are in contact with the constant resistance sleeve. An air tube assembly is installed at the constant resistance body. The air tube assembly is used to inject gas. A solenoid valve is installed at one end of the air tube assembly. A spiral guide rail is provided on the outside of the air tube assembly. A stopper rod is provided on the inside of the air tube assembly. The measuring component is fixed relative to the stopper rod. The constant resistance body is provided with a mounting groove inside. The rollers and sensors are located in the mounting groove. The sensors are fixed relative to the mounting groove. The plunger includes a piston, a plunger, and a connecting cylinder. The piston is slidably connected to the extension tube. A mounting base is fixedly installed on one side of the measuring assembly. The piston, plunger, mounting base, and connecting cylinder are fixed in sequence. A guide block is fixedly installed inside the connecting cylinder. The guide block is located inside the spiral guide rail and is used to move along the spiral guide rail. Construction surveying methods for measurement systems Includes the following steps: S1: The constant resistance body is fixedly connected to the anchor cable steel core through four mounting holes and placed into the constant resistance sleeve as a whole to ensure that the outer ring of the roller is in elastic contact with the inner wall of the constant resistance sleeve. S2: Connect the air tube assembly to the air source, so that the solenoid valve is in the normally open state, inject gas into the air tube assembly, fix the measuring component and the plug rod, and embed the guide block into the spiral guide rail; S3: When the constant resistance body moves along the axial direction of the constant resistance sleeve under the action of external force, multiple rollers rotate synchronously, triggering all sensors to output electrical signals. After series logic processing, the solenoid valve closes the air path, and the measuring component moves synchronously with the constant resistance body, collecting the inner diameter data on the moving path in real time. The data acquisition module synchronously records the sensor's measured value and the position coordinates of the constant resistance body to construct a dynamic inner diameter change curve. S4: When the constant resistance body stops moving, the solenoid valve automatically opens, the plug rod moves axially under air pressure, and the guide block moves along the spiral guide rail, forcing the beam emitted by the measuring component to perform a spiral trajectory scan along the inner wall of the constant resistance sleeve to obtain the inner diameter distribution data within the entire stroke range. By matching the angular velocity of the spiral scan with the linear velocity of the plug rod, the three-dimensional contour reconstruction of the inner wall of the constant resistance sleeve is realized. S5: The continuous point data of dynamic measurement is spatiotemporally registered with the spiral trajectory data of static scanning. By comparing the inner diameter distribution at different time points, the local bulging and shrinkage deformation characteristics of the constant resistance sleeve are identified. Based on the preset threshold, deformation early warning signals are automatically generated to guide the maintenance decisions of slope protection projects.

2. The real-time measurement system for the inner diameter of NPR anchor cables in high slope protection engineering according to claim 1, characterized in that: The roller is rotatably connected to the constant resistance body via a rotating shaft. The inner ring of the roller is made of hard material, and its outer ring is made of soft material. The outer ring is pressed against the inner wall of the constant resistance sleeve and undergoes elastic deformation.

3. The real-time measurement system for the inner diameter of NPR anchor cables in high slope protection engineering according to claim 1, characterized in that: The electrical signals from the multiple sensors are processed in series and then connected to the control terminal of the solenoid valve. The solenoid valve is closed only when all sensors output valid electrical signals.

4. The real-time measurement system for the inner diameter of NPR anchor cables in high slope protection engineering according to claim 1, characterized in that: The tracheal assembly includes a connected internal tube and an extension tube. The internal tube is fixed in the constant resistance body, and the extension tube is fixed to the small-diameter end of the constant resistance body and provides support for the measuring assembly.

5. A real-time measurement system for the inner diameter of NPR anchor cables in high slope protection engineering according to claim 1 or 2, characterized in that: The outer ring of the roller is fixedly connected with several elastic rubber protrusions arranged in a circle.

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