Hollow anchor cable fixed-length accurate squeezing and anchoring method and system

Abstract

The invention discloses a hollow anchor cable fixed-length precise squeezing and anchoring method and system, and relates to the technical field of rock-soil anchoring engineering.The method comprises the steps that a distributed conductivity sensor array is arranged on an anchoring section of a hollow anchor cable, slurry conductivity data are collected in real time in the grouting process, the slurry filling state is judged through an intelligent control unit, and the grouting speed is increased; the system comprises a hollow anchor cable body integrated with a sensor array, an intelligent control unit, the hydraulic feedback type automatic grout stop valve and a hydraulic pump station, closed-loop control is achieved through multi-source information fusion, and the pressure-stabilized grouting is achieved. The device can monitor slurry distribution in real time, accurately control the anchoring length and ensure reliable anchoring quality, is suitable for scenes such as mine roadways, tunnel engineering and slope supporting, and effectively improves the supporting stability and the intelligent level of rock-soil anchoring engineering.

Description

Technical Field

[0001] This invention relates to the field of geotechnical anchoring engineering technology, specifically to a method and system for precise injection anchoring of hollow anchor cables at a fixed length. Background Technology

[0002] Hollow grouting anchors, as key support components in geotechnical anchoring engineering, are widely used in mining roadways, tunnels, and slope protection. Their hollow structure integrates grouting and anchoring functions, effectively improving the integrity and bearing capacity of the surrounding rock. Traditional hollow grouting anchors rely on mechanical grout-stopping devices or empirical grouting processes, indirectly controlling the anchoring length through grouting pressure or time parameters. However, these methods are susceptible to problems such as anchoring length deviations and uneven grout distribution due to drilling geological conditions, grout fluidity, and construction errors. Especially in deep, fractured surrounding rock or complex stress environments, existing technologies struggle to achieve precise control of the anchoring length and real-time sensing of grout distribution, leading to reduced anchoring reliability and even support failure.

[0003] Currently, various improved solutions for hollow grouting anchor cables have been disclosed in relevant patents and literature. For example, the invention patent "Method for Full-Length Anchoring of Hollow Grouting Long Anchor Cable with Prestressed Spring Mechanical Expansion Shell End Anchor" (Publication No. CN114607426A) combines spring mechanical expansion shell with grouting process to achieve end anchoring and full-length anchoring of the anchor cable. However, it relies on the physical expansion shell structure and does not solve the problems of real-time monitoring of grout flow state and dynamic control of anchoring length during grouting. Another invention patent, "A Prestressed Full-Length Anchoring Hollow Grouting Anchor Rod with Expansion Effect" (Publication No. CN112814714B), enhances the anchoring interface stress through the negative Poisson's ratio design of the rod structure. However, its grouting control still relies on static parameters and lacks the ability to sense the grout filling state, making it unable to adapt to the dynamic grouting requirements of fractured rock strata. In addition, some existing technologies have attempted to use conductivity or pressure sensors for grouting monitoring, but these are mostly limited to single parameter feedback and have not formed a closed-loop control system with multi-source information fusion, resulting in insufficient accuracy in anchoring length control.

[0004] Based on the shortcomings of existing technologies, the core problem that this invention aims to solve is the precise control of the anchorage length and real-time sensing of grout distribution during the grouting process. Specifically, existing methods cannot directly obtain the spatial position and filling state of the grout within the borehole, but can only infer it indirectly through pressure or time, leading to problems such as anchorage length deviation, grout leakage, or over-grouting. This problem directly affects the reliability and support effect of the anchorage system, especially when the surrounding rock has developed fissures or the borehole shape is irregular, making it difficult for traditional grouting devices and grouting processes to guarantee the consistency of anchorage quality.

[0005] In summary, while existing hollow grouting anchor technology has achieved some optimization in structural design and grouting process, it still lacks a precise sensing and control mechanism for grout distribution and anchorage length. This invention proposes a fixed-length, precise grouting anchoring method and system by integrating multi-source information sensing and intelligent feedback technologies to solve the aforementioned core problems and improve the intelligence and reliability of anchoring projects. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method and system for precise grouting anchoring of hollow anchor cables. By arranging a distributed conductivity sensor array in the anchoring section of the hollow anchor cable, combined with an intelligent control unit to process the conductivity data of the grout, and a hydraulic feedback automatic grout stop valve for precise sealing, the distribution and filling status of the grout can be monitored in real time, the anchoring length can be precisely controlled, grout leakage or over-grouting can be avoided, and the reliability of the anchoring system and the level of intelligence in geotechnical anchoring engineering can be improved.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: On one hand, a method for precise extrusion anchoring of hollow anchor cables at a fixed length, comprising the following steps:

[0008] S1. A distributed conductivity sensor array is arranged in the anchoring section of the hollow anchor cable. The distributed conductivity sensor array includes multiple electrode pairs arranged at a preset interval.

[0009] S2. Start grouting. The grout is injected from the bottom of the hollow anchor cable and fills the borehole upwards.

[0010] S3. The conductivity data of the slurry is collected in real time through a distributed conductivity sensor array and transmitted to the intelligent control unit;

[0011] S4. The intelligent control unit determines the position and filling status of the grout front based on conductivity data. When it detects that the grout has filled the anchoring section and reached the top of the anchoring section, it generates a control signal.

[0012] S5. The intelligent control unit sends a control signal to the hydraulic feedback automatic grout stop valve, triggering the expansion of the valve's bladder to form an annular sealing strip at the top of the anchoring section, blocking the grout from continuing to flow into the free section.

[0013] S6. After grouting stops, maintain the grouting pressure and perform stable grouting to ensure the compactness of the grout in the anchoring section.

[0014] Furthermore, the intelligent control unit executes a slurry filling degree evaluation algorithm based on data from a distributed conductivity sensor array. This algorithm calculates the slurry filling degree index using the following mathematical formula:

[0015]

[0016] in, Indicates the slurry filling index. Indicates the system calibration coefficient. Indicates the total grouting time. This represents the total number of electrode pairs in a distributed conductivity sensor array. Indicates the first Position weighting coefficients for each electrode pair Indicates the first Each electrode pair in time The conductivity state function;

[0017] System calibration coefficients This is used to adjust the degree of matching between the algorithm output and the actual slurry distribution, and is preset based on experimental data;

[0018] Total grouting time The duration from the start of grouting to the present moment;

[0019] Total number of electrode pairs Determined based on the anchorage length and preset spacing;

[0020] The position weight coefficient Based on the The distance between each electrode pair and the top of the anchoring section is assigned, with closer pairs having higher weights.

[0021] conductivity state function According to the Each electrode pairs the measured conductivity value and assigns a value to the threshold. When the conductivity value exceeds the threshold, It is 1 if it is true, otherwise it is 0;

[0022] The intelligent control unit performs real-time calculations. The value is compared with a preset threshold to determine whether the grout fills the anchoring section and triggers the grout stop action.

[0023] Furthermore, the position weighting coefficient The calculation is based on the geometric distribution model of the anchorage section, and the following mathematical formula is used for dynamic adjustment:

[0024]

[0025] in, Indicates the first Position weighting coefficients for each electrode pair Represents the normalization factor. Indicates the first The straight-line distance from each electrode pair to the top of the anchoring section Represents the mean of the distance distribution. Indicates the standard deviation of the distance distribution;

[0026] Normalization factor This is used to ensure that the sum of all weight coefficients is 1, and is calculated iteratively.

[0027] distance The dimensions of the anchor cable body and the installation position of the electrode pair are directly determined by the design dimensions of the anchor cable body and the installation position of the electrode pair.

[0028] Distance distribution mean Based on the optimized settings of anchorage section length and sensor layout, the expected center point of slurry flow is reflected.

[0029] Distance distribution standard deviation The width of the weight distribution is adaptively adjusted based on the borehole geological conditions.

[0030] The intelligent control unit updates based on real-time geological feedback during the grouting process. and Values ​​are used to optimize weight allocation and improve the accuracy of slurry location determination.

[0031] On the other hand, a hollow anchor cable fixed-length precision injection anchoring system for implementing the method includes:

[0032] A hollow anchor cable body, on which a distributed conductivity sensor array is integrated, the distributed conductivity sensor array including multiple electrode pairs arranged at preset intervals along the anchoring section, each electrode pair being connected to an intelligent control unit via a micro wire;

[0033] A hydraulic feedback automatic grout stop valve is installed at the top of the anchoring section of a hollow anchor cable. The grout stop valve includes a pressure chamber, a flexible bladder, a pressure sensor, and an electromagnetic switch valve. The pressure chamber is connected to a hydraulic pump station via a pipeline. The flexible bladder expands under pressure to form a sealing strip.

[0034] The intelligent control unit is electrically connected to a distributed conductivity sensor array and a hydraulic feedback automatic slurry stop valve. The intelligent control unit is configured to receive and process data from the conductivity sensor array, execute a slurry position determination algorithm, and output control signals to the electromagnetic switch valve.

[0035] A hydraulic pump station, which is connected to the pressure chamber of a hydraulic feedback automatic slurry stop valve via a high-pressure pipeline, provides a controllable hydraulic source to drive the bladder to expand.

[0036] The system achieves closed-loop control of the grouting process through multi-source information fusion, ensuring accurate anchoring length and real-time perception of grout distribution.

[0037] Furthermore, the signal processing module built into the intelligent control unit uses the following mathematical formula to estimate the slurry front velocity:

[0038]

[0039] in, Indicates the average velocity of the slurry front. Indicates the number of activated electrode pairs. Indicates the first Reliability factor of each active electrode pair Indicates the first Axial position coordinates of each active electrode pair Indicates the first Activation timestamps of each electrode pair;

[0040] Number of activated electrode pairs The results are obtained by accumulating the changes in the conductivity state function of the electrode pairs after the start of grouting.

[0041] The reliability factor Based on the Historical data errors and signal strength calculations for each electrode pair are used to improve the accuracy of weighted velocity estimation.

[0042] Axial position coordinates The specific location of the representative electrode pair within the borehole is determined by the anchor cable design drawings and installation records.

[0043] Activation timestamp Recorded from the system clock of the intelligent control unit, when the conductivity state function... Get it when it changes from 0 to 1;

[0044] The intelligent control unit performs real-time calculations. The system predicts the time it takes for the grout to reach the top of the anchoring section and adjusts the triggering parameters of the grout stop valve in advance.

[0045] Furthermore, the reliability factor The calculation is based on a sensor data quality assessment model and is dynamically updated using the following mathematical formula:

[0046]

[0047] in, Indicates the first Reliability factor of each active electrode pair This represents the weighting balance coefficient. Indicates the first Cumulative historical measurement error of each electrode pair This indicates the maximum allowable error threshold of the system. Indicates the first The current signal strength of each electrode pair This indicates the system's preset maximum signal strength;

[0048] Weighting balance coefficient Optimization is achieved through machine learning algorithms to adjust the contribution ratio of error and signal strength to reliability.

[0049] Cumulative value of historical measurement errors It is calculated from the sum of squares of the deviations between the measured and actual values ​​of the electrode pairs in previous grouting cycles;

[0050] Maximum error threshold Pre-set according to engineering precision requirements;

[0051] Current signal strength The output voltage or current value of the conductivity sensor is obtained after analog-to-digital conversion.

[0052] Maximum signal strength Determined based on sensor specifications and circuit design;

[0053] The intelligent control unit is updated regularly. To adapt to sensor aging or environmental changes, ensuring robustness of speed estimation.

[0054] Furthermore, the pressure chamber is made of high-strength alloy, filled with hydraulic oil, and connected to a hydraulic pump station through a sealed interface;

[0055] The flexible capsule is made of elastic polymer material and is wrapped around the outside of the pressure chamber, which expands radially when hydraulic oil is injected.

[0056] The pressure sensor is embedded in the inner wall of the pressure chamber to monitor the hydraulic pressure value in real time and feed it back to the intelligent control unit.

[0057] The electromagnetic switch valve is installed at the inlet of the pressure chamber and is controlled by digital signals from the intelligent control unit to open and close.

[0058] When the intelligent control unit issues a stop-slurry command, the electromagnetic switch valve opens, and hydraulic oil flows from the hydraulic pump station into the pressure chamber, pushing the flexible bladder to expand and press tightly against the borehole wall to form a mechanical seal.

[0059] After the slurry is stopped, the electromagnetic switch valve switches direction, releases hydraulic oil, and the bladder contracts and resets.

[0060] The entire valve body is fixed to the hollow anchor cable body by threads, ensuring structural stability and sealing reliability during the grouting process.

[0061] Furthermore, the distributed conductivity sensor array is arranged in a manner including electrode pairs, microwires, and an insulating layer, wherein the electrode pairs are made of corrosion-resistant metal material and are evenly distributed on the surface of the anchoring section of the anchor cable body at a preset spacing.

[0062] The micro-wires are multi-core shielded cables, with each wire connected to an electrode pair and bundled together along the axial direction of the anchor cable body. An external insulation layer is wrapped around the cable to prevent slurry erosion and electromagnetic interference.

[0063] The insulating layer is extruded from a thermoplastic polymer to ensure electrical isolation between the electrode pair and the slurry;

[0064] The working circuit of each electrode pair includes a constant current source and a voltage measurement module. The constant current source provides a stable excitation current, and the voltage measurement module detects the potential difference between the electrodes and converts it into a conductivity value.

[0065] The intelligent control unit collects data from each electrode pair cyclically through a multiplexer and uses a digital filtering algorithm to reduce noise.

[0066] The installation position of the distributed conductivity sensor array is calculated based on the length of the anchoring section to ensure coverage of the entire area from the start point to the top of the anchoring section, thereby enabling continuous monitoring and precise control of slurry distribution.

[0067] Compared with existing technologies, this method and system for precise fixed-length injection anchoring of hollow anchor cables has the following advantages:

[0068] I. This invention, by arranging a distributed conductivity sensor array in the hollow anchor cable anchoring section and combining it with the grout filling degree evaluation algorithm and the position weight coefficient dynamic adjustment algorithm of the intelligent control unit, can collect grout conductivity data in real time, accurately determine the grout front position and filling state, and then form an annular sealing zone through the timely response of the hydraulic feedback automatic grout stop valve. This achieves precise control of the anchoring length and real-time perception of grout distribution during the grouting process, avoiding problems such as anchoring length deviation, grout leakage or over-grouting caused by the reliance on indirect parameter inference in traditional technologies. It ensures that the anchoring section is completely filled with grout and the length meets the design requirements, significantly improving the reliability and support effect of the anchoring system.

[0069] Second, this invention constructs a closed-loop grouting control system through multi-source information fusion. The intelligent control unit can optimize algorithm parameters in real time to adapt to changes in geological conditions. The hydraulic feedback automatic grout stop valve has stable sealing performance and reset function. Combined with the pressure stabilizing grouting process, it can effectively improve the grout density and the bonding strength of the anchoring interface.

[0070] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0071] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0072] Figure 1 This is a flowchart of the process steps of the present invention;

[0073] Figure 2 This is a diagram showing the structural relationship of the system components of the present invention; Detailed Implementation

[0074] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structure, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0075] Example 1

[0076] like Figure 1 and Figure 2 As shown in the figure, this embodiment discloses a method and system for precise grouting anchoring of hollow anchor cables. To address the problems of insufficient accuracy in anchoring length control and the inability to perceive grout distribution in real time in existing technologies, this embodiment utilizes a distributed conductivity sensor array arranged in the anchoring section of the hollow anchor cable, combined with multi-algorithm fusion processing of an intelligent control unit, and a hydraulic feedback automatic grout stop valve to achieve closed-loop control of the grouting process. This technical solution can monitor the grout front position and filling status in real time, precisely triggering the grout stop action to ensure that the grout in the anchoring section is dense and the anchoring length meets design requirements. This effectively improves the reliability and intelligence level of geotechnical anchoring engineering support, and is applicable to various scenarios such as mine roadways, tunnel engineering, and slope support.

[0077] This embodiment is applied to the surrounding rock support project of a mine roadway. The surrounding rock of the roadway is mainly fractured sandstone, and the stability of the surrounding rock needs to be improved by fixed-length anchoring with hollow anchor cables. The design anchoring section length is determined according to the surrounding rock grade, and the free section length is adapted to the roadway support parameters. The following describes the implementation process of the technical solution in detail with specific implementation steps and system composition:

[0078] Arrangement of distributed conductivity sensor array (corresponding to step S1)

[0079] In this embodiment, the hollow anchor cable body is made of high-strength threaded steel, and the surface of its anchoring section is ground to ensure the stability of the sensor installation. The core component of the distributed conductivity sensor array is the electrode pair, which is made of corrosion-resistant metal material to ensure long-term stable operation in slurry environments.

[0080] The spacing between electrode pairs is determined based on the length of the anchorage section and the required engineering precision. The principle is to cover the entire length of the anchorage section and ensure monitoring density near the top of the anchorage section to improve the accuracy of judgment when the grout reaches the top. After the electrode pairs are evenly distributed along the axial direction of the anchorage section, they are fixed to the surface of the anchor cable body by welding. The welding points are treated with anti-corrosion measures to prevent rust.

[0081] Each electrode pair is independently connected to the intelligent control unit via a micro-wire. The micro-wire uses a multi-core shielded cable, with each wire corresponding to one electrode pair. After all the wires are bundled together along the axial direction of the anchor cable, they are wrapped with a thermoplastic polymer insulation layer. The insulation layer must completely cover the wires and welding points to prevent the grout from corroding the wires during the grouting process and to avoid electromagnetic interference affecting data transmission.

[0082] The installation position of the sensor array is precisely calculated to ensure that the axial position coordinates of the electrode pair are consistent with the design. The position information is pre-stored in the intelligent control unit to provide basic data for subsequent slurry position determination.

[0083] Grouting initiation and grout filling (corresponding to step S2)

[0084] Before grouting, the borehole is cleaned to remove rock debris and water, ensuring smooth grout flow. In this embodiment, cement grout is used as the grouting material. After being thoroughly mixed, the grout is injected into the grouting equipment, which is then sealed to the bottom interface of the hollow anchor cable via pipeline.

[0085] After the grouting equipment is started, the grout is injected from the bottom of the hollow anchor cable body under pressure, filling upwards along the annular gap between the borehole and the anchor cable body. The grouting pressure is set according to the development of surrounding rock fissures. The initial pressure is designed to push the grout to rise steadily, avoiding excessive pressure that could lead to the expansion of surrounding rock fissures or grout loss.

[0086] Real-time acquisition and transmission of conductivity data (corresponding to step S3)

[0087] Each electrode pair integrates a constant current source and a voltage measurement module in its operating circuit. The constant current source provides a stable excitation current to the electrode pair, ensuring that the measurement accuracy is not affected by power fluctuations. When the slurry has not reached the electrode pair, the space between the electrodes is filled with air or rock, resulting in a low conductivity value. When the slurry comes into contact with the electrode pair, the conductivity of the medium changes significantly. The voltage measurement module detects the potential difference between the electrodes and converts it into conductivity data.

[0088] The intelligent control unit cyclically collects conductivity data from each electrode pair via a multiplexer. The collection frequency is set according to the slurry flow velocity to ensure the dynamic changes of the slurry front are captured. During the collection process, a digital filtering algorithm is used to process the raw data, filtering out environmental interference and sensor noise to ensure data accuracy. The processed conductivity data is transmitted in real time to the signal processing module of the intelligent control unit, providing the raw data for subsequent algorithm calculations.

[0089] Slurry filling status judgment and control signal generation (corresponding to step S4)

[0090] After receiving conductivity data, the intelligent control unit calculates the slurry filling index using a slurry filling degree evaluation algorithm. This is used to determine the filling state of the slurry. The algorithm formula is as follows:

[0091]

[0092] The detailed explanation and calculation logic of each parameter are as follows:

[0093] The grout filling index is used to quantify the degree of grout filling within the anchorage section. Its numerical range and preset threshold are calibrated experimentally. When the preset threshold is reached, it is determined that the grout has filled the anchoring section.

[0094] This is a system calibration coefficient used to adjust the matching degree between the algorithm output and the actual grout distribution. It is pre-set through multiple sets of indoor simulated grouting experiments. During the calibration process, the algorithm's calculated values ​​are compared with the actual grout filling conditions to optimize the system. The value is chosen to reduce error.

[0095] The total grouting time is the duration from the start of grouting to the current data acquisition time, which is automatically recorded by the system clock of the intelligent control unit.

[0096] The total number of electrode pairs in the distributed conductivity sensor array is determined based on the length of the anchoring section and the spacing between the electrode pairs, ensuring that the electrode pairs can fully cover the anchoring section without any monitoring blind spots.

[0097] For the first The positional weighting coefficients for each electrode pair are assigned based on the principle that the closer the electrode pair is to the top of the anchorage section, the higher its weight. This improves the sensitivity of the judgment when the grout reaches the top of the anchorage section. Dynamically adjust using the following formula:

[0098]

[0099] The parameters in this formula are explained below:

[0100] The normalization factor ensures that the sum of the position weight coefficients of all electrode pairs is 1. It is calculated iteratively, with the sum of the weight coefficients being 1 as a constraint during the iteration process.

[0101] For the first The straight-line distance from each electrode pair to the top of the anchoring section is directly determined by the design dimensions of the anchor cable body and the installation position of the electrode pair, and its value is pre-stored in the intelligent control unit.

[0102] The distance distribution average is set based on the anchorage section length and sensor layout optimization, reflecting the expected center point of grout flow, i.e. the distance corresponding to the position when the grout fills to the middle of the anchorage section under ideal conditions.

[0103] The standard deviation of the distance distribution is adaptively adjusted according to the borehole geological conditions. When the surrounding rock fractures are more severe, Increasing the value expands the weight distribution width and improves the algorithm's robustness; when the surrounding rock integrity is good, The value is reduced to concentrate the weight distribution and improve the accuracy of judgment. During the grouting process, the intelligent control unit updates the data in real time based on the grout flow status fed back by conductivity data. and Values, optimize weight allocation.

[0104] For the first Each electrode pair in time The conductivity state function is assigned according to the following rule: the conductivity value measured by the electrode pair is compared with a preset threshold. When the measured value exceeds the threshold, it is determined that the slurry has reached the position of the electrode pair. If the measured value does not exceed the threshold, it is determined that the slurry has not arrived. The conductivity threshold was determined experimentally. The conductivity values ​​of air, rock strata, and slurry were measured separately, and the minimum conductivity value of the slurry was used as the threshold.

[0105] The intelligent control unit calculates the slurry filling index in real time. And continuously compare it with a preset threshold. When When the preset threshold is reached, it is determined that the grout has filled the anchoring section and reached the top of the anchoring section, and then a grout stop control signal is generated.

[0106] Hydraulic feedback automatic grout stop valve triggering (corresponding to step S5)

[0107] The hydraulic feedback automatic grout stop valve is installed at the top of the anchoring section of the hollow anchor cable body and is fixed to the anchor cable body by threads to ensure a firm installation and reliable seal. This grout stop valve mainly consists of a pressure chamber, a flexible bladder, a pressure sensor, and an electromagnetic switch valve. The pressure chamber is made of high-strength alloy and filled with hydraulic oil, connected to the high-pressure pipeline of the hydraulic pump station through a sealed interface. The flexible bladder is made of elastic polymer material and tightly wraps around the outside of the pressure chamber, possessing excellent expansion and contraction performance. The pressure sensor is embedded in the inner wall of the pressure chamber, monitoring the hydraulic pressure value in real time and feeding it back to the intelligent control unit. The electromagnetic switch valve is installed at the inlet of the pressure chamber, electrically connected to the intelligent control unit, and receives control signals to open and close.

[0108] When the intelligent control unit sends a grout-stopping control signal, the electromagnetic switch valve immediately opens, and the hydraulic pump station injects hydraulic oil into the pressure chamber, causing the hydraulic pressure value inside the chamber to gradually increase. The pressure sensor feeds back the hydraulic data to the intelligent control unit in real time, forming a closed-loop pressure control to ensure that the hydraulic pressure value remains stable within the preset range. Under the action of hydraulic pressure, the flexible bladder expands radially, tightly fitting against the borehole wall to form an annular sealing band, completely blocking the grout from continuing to flow into the free section, achieving precise grout-stopping.

[0109] After the grouting is stopped, the electromagnetic switch valve switches direction according to the instructions of the intelligent control unit. The hydraulic oil in the pressure chamber flows back to the hydraulic pump station, and the flexible bladder contracts and resets under its own elasticity, which facilitates subsequent anchor cable tensioning and other processes.

[0110] Pressure-stabilizing grouting (corresponding to step S6)

[0111] After the grouting is stopped, the grouting equipment maintains the current grouting pressure for stabilizing grouting. The stabilization time is determined based on the grout setting characteristics and engineering requirements. The purpose of stabilizing grouting is to ensure that the grout in the anchoring section fully fills the cracks, removes residual air, and improves the grout density and bond strength at the anchoring interface.

[0112] During the pressure stabilization process, the intelligent control unit continuously receives conductivity data from the distributed conductivity sensor array and hydraulic data from the pressure sensor. If abnormal fluctuations occur in the conductivity data, it indicates potential grout leakage. The intelligent control unit will adjust the output pressure of the hydraulic pump station to further expand the flexible bladder and enhance the sealing effect. If the grouting pressure rises abnormally, it will appropriately reduce the grouting pressure to avoid damaging the anchor cable or surrounding rock. After the pressure stabilization grouting is completed, the grouting equipment is shut down, completing the entire anchoring process.

[0113] In this embodiment, the hollow anchor cable fixed-length precision injection anchoring system achieves closed-loop control through multi-source information fusion. The collaborative workflow of each component is as follows:

[0114] The distributed conductivity sensor array is responsible for collecting slurry conductivity data, providing a sensing basis for determining the slurry location and filling status.

[0115] The intelligent control unit, as the core control module, receives sensor data and processes it comprehensively through algorithms such as slurry filling degree evaluation algorithm, position weight coefficient dynamic adjustment algorithm, slurry front velocity estimation algorithm, and reliability factor update algorithm to generate control commands.

[0116] The hydraulic pump station responds to the instructions of the intelligent control unit, providing a stable and controllable hydraulic source to drive the slurry stop valve to operate;

[0117] The hydraulic feedback automatic grout stop valve achieves precise grout stop according to control commands, and at the same time, it feeds back hydraulic data through a pressure sensor to form a control closed loop.

[0118] The intelligent control unit incorporates a grout front velocity estimation algorithm to predict the time it takes for the grout to reach the top of the anchoring section, allowing for advance adjustment of the grout stop valve's triggering parameters. The algorithm formula is as follows:

[0119]

[0120] The parameters in the formula are explained below:

[0121] The average velocity of the slurry front reflects the dynamic speed of the slurry filling upwards, providing data support for predicting arrival time.

[0122] The number of activated electrode pairs, i.e., the conductivity state function after grouting begins. The cumulative number of electrode pairs that change from 0 to 1 is counted in real time by the intelligent control unit.

[0123] For the first The reliability factor of each active electrode pair, used to weight the accuracy of the speed estimation, is calculated as follows:

[0124]

[0125] The parameters in this formula are explained below:

[0126] The weighting balancing coefficient is used to adjust the contribution ratio of historical measurement errors and current signal strength in reliability assessment. It is obtained through optimization using machine learning algorithms, with the goal of minimizing the deviation between the speed estimate and the actual value during the optimization process.

[0127] For the first The cumulative historical measurement error of each electrode pair is obtained by summing the squares of the deviations between the measured values ​​of the electrode pair and the actual grout position from the grouting cycles of similar projects in the past.

[0128] The maximum allowable error threshold of the system is preset according to the engineering accuracy requirements to ensure that the value of the reliability factor is within a reasonable range.

[0129] For the first The current signal strength of each electrode pair is obtained by analog-to-digital conversion of the output voltage or current value of the conductivity sensor. The higher the signal strength, the more reliable the measurement data.

[0130] The maximum signal strength preset for the system is determined based on the sensor's technical specifications and circuit design, reflecting the sensor's optimal operating state.

[0131] The intelligent control unit is updated regularly. To adapt to performance fluctuations caused by sensor aging or environmental changes, and to ensure the robustness of speed estimation.

[0132] For the first The axial position coordinates of each active electrode pair are determined by the anchor body design drawings and installation records, and are pre-stored in the intelligent control unit, representing the specific position of the electrode pair in the borehole.

[0133] For the first The axial position coordinates of each active electrode pair, and The distance between adjacent active electrode pairs is calculated in conjunction with this calculation.

[0134] For the first The activation timestamp of each electrode pair, i.e. The moment when the value changes from 0 to 1 is precisely recorded by the system clock of the intelligent control unit.

[0135] For the first The activation timestamps of each electrode pair, and Combined with calculation of slurry from the first The electrode pair flows to the first The time for each electrode pair.

[0136] Through real-time calculation The intelligent control unit can predict the time it takes for the grout to reach the top of the anchoring section and adjust the response parameters of the electromagnetic switch valve and the pressure output curve of the hydraulic pump station in advance to ensure the timeliness and accuracy of the grout stopping action.

[0137] In summary, this embodiment achieves real-time sensing of grout distribution through a distributed conductivity sensor array. Combined with multi-algorithm fusion processing by the intelligent control unit, it accurately determines the grout filling state and leading edge position. Then, a hydraulic feedback automatic grout stop valve achieves timely and reliable grout stopping action. Finally, pressure-stabilized grouting ensures the grout density of the anchoring section. The entire technical solution forms a closed-loop system of "sensing-computation-control-execution," effectively solving the defects of inaccurate anchoring length control and inability to monitor grout distribution in real time in existing technologies.

[0138] Example 2

[0139] like Figure 1 and Figure 2 As shown, this embodiment is applied to the support engineering of weak surrounding rock in urban subway tunnels. Addressing the problems of easy collapse in weak surrounding rock and the difficulty in accurately controlling the anchorage range using traditional grouting methods, a distributed conductivity sensor array is integrated into the anchorage section of the hollow anchor cable. This, combined with real-time data processing by the intelligent control unit and the precise action of the hydraulic feedback automatic grout stop valve, enables full monitoring and fixed-length grout stop during the grouting process. This solution ensures uniform grout filling in the anchorage section and that the anchorage length meets design requirements, effectively improving the stability and safety of tunnel surrounding rock support. It is suitable for anchorage projects under various conditions of weak and fractured surrounding rock.

[0140] This embodiment addresses the design of a section of a subway tunnel with alternating layers of silty clay and sand. This section of surrounding rock has poor self-stabilizing capacity, requiring fixed-length hollow anchor cables to limit deformation. The designed anchoring section must be fully embedded in the stable rock layer, while the free section must be adapted to the thickness of the tunnel lining structure. The following details the actual implementation of the technical solution, combining the on-site construction process and system component collaboration details:

[0141] The system components are prefabricated and assembled as follows:

[0142] The hollow anchor cable body is made of high-strength, low-relaxation steel strand. The surface of its anchoring section is sandblasted to remove the oxide layer and enhance the bonding force with the sensor assembly. The electrode pairs of the distributed conductivity sensor array are made of rust-resistant alloy material and are designed in an arc-shaped plate shape to match the curvature of the anchor cable body surface, ensuring a tight fit.

[0143] When laying out the electrodes, they are arranged along the axial direction of the anchorage section according to a preset pattern, covering the entire length of the anchorage section from bottom to top. Within the last third of the anchorage section near the top, the spacing between the electrodes is appropriately reduced to improve the monitoring sensitivity when the grout reaches the top. The electrodes are fixed to the anchor cable body using laser welding. After welding, the weld joints are treated with an anti-corrosion coating, using the same material as the anti-corrosion coating on the anchor cable body, to prevent corrosion of the weld joints from affecting sensor performance.

[0144] The micro-conductors are made of multi-core shielded cable, with each conductor corresponding to one electrode pair. When the conductors are laid along the axial direction of the anchor cable, they are secured with special clamps. The clamp spacing matches the electrode pair spacing to prevent displacement of the conductors during transportation and installation. The conductor bundle is externally wrapped with a thermoplastic polymer insulation layer. This insulation layer is applied to the conductor bundle using an extrusion molding process, ensuring the insulation layer is free of bubbles and damage, and adheres tightly to the anchor cable surface to form a complete protective layer, preventing direct contact between the grout and the conductors.

[0145] Hydraulic feedback automatic slurry stop valve assembly

[0146] The pressure chamber of the hydraulic feedback automatic slurry stop valve is forged from high-strength aluminum alloy. The interior of the chamber is precision-machined to ensure a smooth, burr-free inner wall, reducing hydraulic oil flow resistance. The flexible bladder is made of oil-resistant elastic rubber, and its inner side is fixed to the outer wall of the pressure chamber through a vulcanization process. After vulcanization, a sealing test is performed to ensure no hydraulic oil leakage.

[0147] The pressure sensor is a miniature diffused silicon pressure sensor, which is embedded in a pre-drilled hole in the inner wall of the pressure chamber via a threaded connection. The sensor probe is in direct contact with the hydraulic oil in the chamber, and its signal cable is led out through a sealed hole in the side wall of the pressure chamber. The sealed hole is double-sealed with a sealing ring and sealant to prevent hydraulic oil leakage. The solenoid valve is a two-position three-way solenoid directional valve, which is installed at the oil inlet of the pressure chamber via a flange connection. A metal gasket is installed at the flange connection, and a torque wrench is used to control the tightening force when tightening the bolts to ensure reliable sealing.

[0148] The connection between the grout stop valve and the hollow anchor cable body is a threaded fit. The top of the anchor cable body has a pre-set external thread, and the inside of the grout stop valve has a pre-set internal thread. During assembly, apply thread sealant to the thread and then tighten the grout stop valve to the top of the anchor cable body with a wrench to ensure that the axis of the grout stop valve coincides with the axis of the anchor cable body, so as to avoid misalignment affecting the expansion and sealing effect of the bladder.

[0149] The intelligent control unit connects to each component.

[0150] The intelligent control unit uses an industrial-grade PLC controller with a waterproof and dustproof casing, suitable for tunnel construction site environments. The controller's signal input interface is connected to the fine wires of the distributed conductivity sensor array via shielded cables. Each sensor signal corresponds to an independent interface, facilitating fault diagnosis. The controller's control output interface is connected to the coil of the solenoid valve via a cable, and also to the control module of the hydraulic pump station via a communication cable, enabling coordinated control of the hydraulic system.

[0151] After the connection is completed, power on the system for debugging and check whether each sensor can output signals normally, whether the solenoid valve can respond to the controller command, and whether the pressure sensor can accurately feed back pressure data, to ensure that all components communicate smoothly and function normally.

[0152] The on-site drilling and anchor installation are as follows:

[0153] A hydraulic rock drill was used for drilling. The borehole diameter was matched to the hollow anchor cable body, and the drilling depth was determined by the sum of the designed anchorage section and free section lengths. During the drilling process, ground-penetrating radar was used to monitor the stability of the borehole wall in real time. If borehole wall collapse occurred, casing was promptly used for follow-up support to ensure the quality of the borehole formation.

[0154] After drilling is completed, compressed air is introduced into the hole using a high-pressure air gun to remove residual rock cuttings, soil, and water until the air discharged from the hole is free of obvious impurities. After cleaning, the hole wall is inspected with an endoscope to confirm that there are no obvious cracks or collapses in the hole wall and that the drilling depth meets the design requirements.

[0155] The prefabricated hollow anchor cable body is slowly lowered into the borehole using mechanical hoisting equipment. The lowering speed is controlled uniformly during the process to avoid severe friction between the anchor cable body and the borehole wall, which could damage the sensor array or insulation layer. Lowering stops when the top of the anchor cable body reaches the designed position at the borehole opening. The anchor cable body is then fixed using a positioning bracket to ensure that the anchored section is completely within the designed stable rock strata, and that the length of the free section extending beyond the borehole opening meets the requirements for subsequent lining construction.

[0156] After positioning was completed, the signal of the distributed conductivity sensor array was checked again to confirm that the sensor was not damaged during the lowering process and that the signal transmission was normal.

[0157] The grouting equipment commissioning and grouting start-up are as follows:

[0158] The grouting equipment uses a screw-type grouting pump with adjustable output pressure and flow rate to meet the grouting requirements of this embodiment. The grout is a cement-water glass two-component grout, mixed uniformly in a mixing tank according to the designed ratio. A tachometer is used to control the mixing speed during the mixing process to ensure uniform mixing and prevent clumping. After mixing, the grout density is measured using a grout density meter; it can only be used after confirming that it meets the design requirements.

[0159] The grouting pipeline uses a high-pressure rubber hose, with one end connected to the output port of the grouting pump and the other end connected to the grouting interface at the bottom of the hollow anchor cable. The connection is secured with clamps and sealed with sealing tape to ensure a tight seal. After the pipeline connection is completed, clean water is introduced into the pipeline for pressure testing. The test pressure is set at 1.2 times the design grouting pressure. After maintaining the pressure for a period of time, the joints of the pipeline are checked for leaks. Once no leaks are confirmed, the clean water is drained, and preparation for grouting is made.

[0160] Start the grouting pump and slowly increase the grouting pressure in the initial stage until the grout is injected into the hole from the bottom of the anchor cable. During the grouting process, the grout output flow rate is monitored in real time through the grouting pump's flow monitoring module to maintain a stable flow rate and avoid sudden increases in flow rate that could cause a sudden change in the pressure inside the hole, leading to hole wall collapse or grout loss.

[0161] Grout monitoring and grout stop triggering are as follows:

[0162] The intelligent control unit receives conductivity data transmitted from the distributed conductivity sensor array in real time and dynamically displays the monitoring status of each electrode pair on the controller's display interface. When the grout fills upward from the bottom of the anchor cable and contacts the electrode pair below, the conductivity data of the corresponding electrode pair changes significantly, and the status marker of that electrode pair on the display interface switches from "not in contact" to "in contact," allowing operators to intuitively grasp the movement trajectory of the grout front.

[0163] If the conductivity data of an electrode pair in a certain area remains unchanged for a long time during the monitoring process, the intelligent control unit will automatically issue an alarm signal, indicating that there may be obstruction of grout flow or grout leakage due to cracks in the borehole wall. At this time, the operator can adjust the grouting pressure appropriately, and at the same time observe the distribution of grout in the borehole through ground radar to investigate the cause of the abnormality and take targeted measures.

[0164] When the grout front moves to the top of the anchoring section and all electrode pairs in the top area report a "contacted" status, the intelligent control unit automatically generates a grout-stopping control signal and sends it to the solenoid valve and hydraulic pump station. After receiving the signal, the solenoid valve switches to the conducting state, and the hydraulic pump station injects hydraulic oil into the pressure chamber of the grout-stopping valve. The pressure in the pressure chamber gradually increases, pushing the flexible bladder to expand radially.

[0165] The pressure sensor feeds back the pressure data inside the chamber to the intelligent control unit in real time. When the pressure reaches the preset sealing pressure value, the intelligent control unit controls the hydraulic pump station to stop supplying oil, maintaining stable chamber pressure. At this time, the orifice is observed through an endoscope to confirm that no slurry flows from the top of the anchoring section to the free section, and that the orifice wall is tightly fitted to the bladder body, indicating that the sealing effect meets the requirements.

[0166] The connection between pressure-stabilized grouting and subsequent processes is as follows:

[0167] After the grout sealing is completed, maintain the output pressure of the grouting pump at the designed stable pressure value and perform pressure-stabilized grouting. During the pressure stabilization process, the intelligent control unit continuously monitors the grouting pressure and the status of each sensor. If the pressure drops, it automatically controls the grouting pump to replenish grout and maintain pressure stability; if the pressure rises abnormally, it promptly reduces the grouting pressure to avoid damaging the anchor cable body or the borehole wall.

[0168] After the pressure stabilization time reaches the design requirements, the grouting pump is turned off, grouting is stopped, and the grout filling of the anchoring section is completed.

[0169] After grouting is completed and the grout has initially solidified, the intelligent control unit sends a reset signal, the electromagnetic switch valve switches to the pressure relief state, the hydraulic oil in the pressure chamber flows back to the hydraulic pump station, and the flexible bladder contracts and resets under its own elasticity.

[0170] After resetting, check the connection status between the grout stop valve and the anchor cable body to confirm that there is no grout residue affecting subsequent procedures. Then, conduct a pre-tensioning inspection of the hollow anchor cable body, including the signal integrity of the sensor array and the appearance of the anchor cable body, to ensure that the tensioning conditions are met and to lay the foundation for the subsequent anchor cable tensioning process.

[0171] In summary, this embodiment ensures reliable functionality and smooth collaboration among components through meticulous prefabrication and assembly of system components. By optimizing operational details in drilling, anchor installation, and grouting adjustments based on actual on-site construction conditions, it addresses the challenges of drilling formation and sensor damage in soft surrounding rock conditions. Furthermore, the combination of real-time monitoring and precise grout stopping achieves uniform filling and length control of the anchoring section. The entire implementation process conforms to on-site construction specifications, and all operational steps are repeatable and verifiable.

[0172] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for precise injection molding and anchoring of hollow anchor cables at a fixed length, characterized in that, Includes the following steps: S1. A distributed conductivity sensor array is arranged in the anchoring section of the hollow anchor cable. The distributed conductivity sensor array includes multiple electrode pairs arranged at a preset interval. S2. Start grouting. The grout is injected from the bottom of the hollow anchor cable and fills the borehole upwards. S3. The conductivity data of the slurry is collected in real time through a distributed conductivity sensor array and transmitted to the intelligent control unit; S4. The intelligent control unit determines the position and filling status of the grout front based on conductivity data. When it detects that the grout has filled the anchoring section and reached the top of the anchoring section, it generates a control signal. S5. The intelligent control unit sends a control signal to the hydraulic feedback automatic grout stop valve, triggering the expansion of the valve's bladder to form an annular sealing strip at the top of the anchoring section, blocking the grout from continuing to flow into the free section. S6. After grouting stops, maintain the grouting pressure and perform pressure-stabilized grouting.

2. The method for precise extrusion anchoring of hollow anchor cables to a fixed length according to claim 1, characterized in that, The intelligent control unit executes a slurry filling degree evaluation algorithm based on data from a distributed conductivity sensor array. The slurry filling degree evaluation algorithm calculates the slurry filling index using the following mathematical formula: in, Indicates the slurry filling index. Indicates the system calibration coefficient. Indicates the total grouting time. This represents the total number of electrode pairs in a distributed conductivity sensor array. Indicates the first Position weighting coefficients for each electrode pair Indicates the first Each electrode pair in time The conductivity state function; System calibration coefficients This is used to adjust the degree of matching between the algorithm output and the actual slurry distribution, and is preset based on experimental data; Total grouting time The duration from the start of grouting to the present moment; Total number of electrode pairs Determined based on the anchorage section length and preset spacing; The position weight coefficient Based on the The distance between each electrode pair and the top of the anchoring section is assigned, with closer pairs having higher weights. conductivity state function According to the Each electrode pairs the measured conductivity value and assigns a value to the threshold. When the conductivity value exceeds the threshold, It is 1 if it is true, otherwise it is 0; The intelligent control unit performs real-time calculations. The value is compared with a preset threshold to determine whether the grout fills the anchoring section and triggers the grout-stopping action.

3. The method for precise extrusion anchoring of hollow anchor cables according to claim 2, characterized in that, The position weight coefficient The calculation is based on the geometric distribution model of the anchorage section, and the following mathematical formula is used for dynamic adjustment: in, Indicates the first Position weighting coefficients for each electrode pair Represents the normalization factor. Indicates the first The straight-line distance from each electrode pair to the top of the anchoring section Represents the mean of the distance distribution. Indicates the standard deviation of the distance distribution; Normalization factor This is used to ensure that the sum of all weight coefficients is 1, and is calculated iteratively. distance The dimensions of the anchor cable body and the installation position of the electrode pair are directly determined by the design dimensions of the anchor cable body and the installation position of the electrode pair. Distance distribution mean Based on the optimized settings of anchorage section length and sensor layout, the expected center point of slurry flow is reflected. Distance distribution standard deviation The width of the weight distribution is adaptively adjusted based on the borehole geological conditions. The intelligent control unit updates based on real-time geological feedback during the grouting process. and value.

4. A hollow anchor cable fixed-length precision injection anchoring system for implementing the method of claim 1, characterized in that, include: A hollow anchor cable body, on which a distributed conductivity sensor array is integrated, the distributed conductivity sensor array including multiple electrode pairs arranged at preset intervals along the anchoring section, each electrode pair being connected to an intelligent control unit via a micro wire; A hydraulic feedback automatic grout stop valve is installed at the top of the anchoring section of a hollow anchor cable. The grout stop valve includes a pressure chamber, a flexible bladder, a pressure sensor, and an electromagnetic switch valve. The pressure chamber is connected to a hydraulic pump station via a pipeline. The flexible bladder expands under pressure to form a sealing strip. The intelligent control unit is electrically connected to a distributed conductivity sensor array and a hydraulic feedback automatic slurry stop valve. The intelligent control unit is configured to receive and process data from the conductivity sensor array, execute a slurry position determination algorithm, and output control signals to the electromagnetic switch valve. A hydraulic pump station, which is connected to the pressure chamber of a hydraulic feedback automatic slurry stop valve via a high-pressure pipeline, provides a controllable hydraulic source to drive the bladder to expand. The system achieves closed-loop control of the grouting process through multi-source information fusion.

5. The hollow anchor cable fixed-length precision injection anchoring system according to claim 4, characterized in that, The signal processing module built into the intelligent control unit uses the following mathematical formula to estimate the slurry front velocity: in, Indicates the average velocity of the slurry front. Indicates the number of activated electrode pairs. Indicates the first Reliability factor of each active electrode pair Indicates the first Axial position coordinates of each active electrode pair Indicates the first Activation timestamps of each electrode pair; Number of activated electrode pairs The results are obtained by accumulating the changes in the conductivity state function of the electrode pairs after the start of grouting. The reliability factor Based on the Historical data errors and signal strength calculations for each electrode pair are used to improve the accuracy of weighted velocity estimation. Axial position coordinates The specific location of the representative electrode pair within the borehole is determined by the anchor cable design drawings and installation records. Activation timestamp Recorded from the system clock of the intelligent control unit, when the conductivity state function... Get it when it changes from 0 to 1; The intelligent control unit performs real-time calculations. The system predicts the time it takes for the grout to reach the top of the anchoring section and adjusts the triggering parameters of the grout stop valve in advance.

6. The hollow anchor cable fixed-length precision injection anchoring system according to claim 5, characterized in that, The reliability factor The calculation is based on a sensor data quality assessment model and is dynamically updated using the following mathematical formula: in, Indicates the first Reliability factor of each active electrode pair This represents the weighting balance coefficient. Indicates the first Cumulative historical measurement error of each electrode pair This indicates the maximum allowable error threshold of the system. Indicates the first The current signal strength of each electrode pair This indicates the system's preset maximum signal strength; Weighting balance coefficient Optimize using machine learning algorithms to adjust the contribution ratio of error and signal strength to reliability; Cumulative value of historical measurement errors It is calculated from the sum of squares of the deviations between the measured and actual values ​​of the electrode pairs in previous grouting cycles; Maximum error threshold Pre-set according to engineering precision requirements; Current signal strength The output voltage or current value of the conductivity sensor is obtained after analog-to-digital conversion. Maximum signal strength Determined based on sensor specifications and circuit design; The intelligent control unit is updated regularly. To adapt to sensor aging or environmental changes.

7. The hollow anchor cable fixed-length precision injection anchoring system according to claim 4, characterized in that, The pressure chamber is filled with hydraulic oil and connected to a hydraulic pump station through a sealed interface; The flexible bladder is wrapped around the outside of the pressure chamber and expands radially when hydraulic oil is injected; The pressure sensor is embedded in the inner wall of the pressure chamber to monitor the hydraulic pressure value in real time and feed it back to the intelligent control unit. The electromagnetic switch valve is installed at the inlet of the pressure chamber and is controlled by digital signals from the intelligent control unit to open and close. When the intelligent control unit issues a stop-slurry command, the electromagnetic switch valve opens, and hydraulic oil flows from the hydraulic pump station into the pressure chamber, pushing the flexible bladder to expand and adhere tightly to the borehole wall, forming a mechanical seal. After the slurry is stopped, the electromagnetic switch valve switches direction, releases hydraulic oil, and the bladder contracts and resets. The entire valve body is fixed to the hollow anchor cable body by threads.

8. The hollow anchor cable fixed-length precision injection anchoring system according to claim 4, characterized in that, The distributed conductivity sensor array is arranged in the form of electrode pairs, micro wires and an insulating layer, wherein the electrode pairs are evenly distributed on the surface of the anchoring section of the anchor cable body at a preset interval. The micro-wires are multi-core shielded cables, with each wire connected to an electrode pair and bundled together along the axial direction of the anchor cable body. An external insulation layer is wrapped around the cable to prevent slurry erosion and electromagnetic interference. The working circuit of each electrode pair includes a constant current source and a voltage measurement module. The constant current source provides a stable excitation current, and the voltage measurement module detects the potential difference between the electrodes and converts it into a conductivity value. The intelligent control unit collects data from each electrode pair cyclically through a multiplexer and uses a digital filtering algorithm to reduce noise. The installation location of the distributed conductivity sensor array is calculated based on the length of the anchoring section.

Images