Optical cable and soil coupling performance testing device and testing method

Abstract

This invention relates to the field of optical cable testing technology, and in particular to a testing device and method for testing the coupling performance of optical cables with soil. Regarding the testing device, a relative-slip test chamber is used to accommodate a soil sample; a vertical loading mechanism is used to apply a vertical load to the soil sample within the relative-slip test chamber; a transverse loading assembly is used to apply a transverse load to the test chamber assembly; the test optical cable is inserted inside the relative-slip test chamber and is wrapped by the soil sample; the optical cable tensioning mechanism and the optical cable fixing fixture work together to apply pre-tension stress to the test optical cable, maintaining deformation coupling with the soil sample. During the test, real-time deformation data of the soil sample and strain response data of the test optical cable are simultaneously acquired, comprehensively recording the mechanical changes throughout the entire process from elastic coupling and micro-slippage to debonding failure between the test optical cable and the soil sample, thereby achieving multi-dimensional, full-process quantitative testing of the coupling performance between the optical cable and soil.

Description

Technical Field

[0001] This invention relates to the field of optical cable testing technology, and in particular to a testing device and method for testing the coupling performance between optical cables and soil. Background Technology

[0002] Distributed fiber optic sensing technology has been widely used in long-term monitoring scenarios such as deformation, settlement, and slippage in geotechnical engineering. The deformation coupling performance between the optical cable and the surrounding soil is the core key to determining the accuracy and effectiveness of fiber optic monitoring data.

[0003] To accurately determine the sensing response characteristics of optical cables in soil, it is necessary to quantitatively test and calibrate the coupling performance between the optical cable and the soil through indoor experiments. Currently, most optical cable-soil coupling performance testing devices use a fixed, enclosed structure for their test chambers. This means they can only perform vertical compaction loading tests and cannot achieve lateral relative sliding adjustment of the chamber, making it difficult to simulate real engineering conditions where soil undergoes lateral shear deformation under load.

[0004] In actual testing, traditional testing equipment can only collect cable-soil coupling data under a single vertical load, and cannot simultaneously test the cable-soil interface state during the gradual lateral deformation of the soil. It is difficult to fully capture the mechanical response of the cable-soil from elastic coupling and micro-slippage to debonding failure, resulting in a single dimension of cable-soil coupling performance testing and insufficient accuracy of quantitative evaluation results.

[0005] Therefore, it is urgent for technical personnel to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a testing device for the coupling performance of optical cables and soil, which aims to solve the problems of existing testing devices that cannot achieve lateral relative sliding adjustment of the cavity, can only carry out single vertical loading tests, cannot simulate the lateral shearing conditions of soil, and are difficult to fully capture the entire process of cable-soil coupling failure.

[0007] This invention relates to a testing device for the coupling performance of optical cable and soil, comprising a base, an optical cable tensioning mechanism, a horizontal loading mechanism, a vertical loading mechanism, a relative sliding test chamber, and an optical cable fixing fixture; The optical cable tensioning mechanism, the lateral loading mechanism, the relative sliding test chamber, and the optical cable fixing fixture are all installed and fixed on the base; The relative sliding test chamber is used to hold soil samples; The vertical loading mechanism is installed on the top wall of the relative sliding test chamber and is used to apply vertical loads to the soil sample inside the relative sliding test chamber. The lateral loading assembly is used to apply lateral loads to the test chamber assembly, causing lateral deformation of the soil sample. The test optical cable is inserted inside the relative slip test chamber and wrapped by the soil sample; the optical cable tensioning mechanism and the optical cable fixing fixture are arranged opposite each other, and the two work together to apply pre-tension stress to the test optical cable and keep the test optical cable and the soil sample deformably coupled.

[0008] As a further improvement to the technical solution disclosed in this invention, the relative sliding test chamber includes a main chamber and an embedded chamber that are nested together and slide relative to each other in the lateral direction.

[0009] As a further improvement to the technical solution disclosed in this invention, the lateral loading mechanism is composed of a left loading fixture and a right loading fixture; the left loading fixture and the right loading fixture are respectively matched with the main chamber and the embedded chamber to drive them to slide relative to each other in the lateral direction.

[0010] As a further improvement to the technical solution disclosed in this invention, the vertical loading mechanism comprises a left-side vertical loading sub-mechanism and a right-side vertical loading sub-mechanism; the left-side vertical loading sub-mechanism and the right-side vertical loading sub-mechanism are respectively matched with the main chamber and the embedded chamber, and are used to apply vertical loads to the soil samples in both chambers.

[0011] As a further improvement to the technical solution disclosed in this invention, the optical cable tensioning mechanism includes an optical cable tensioning seat, a linear drive component, and a tensioning reaction frame; the tensioning reaction frame is fixed to the base; the drive component is used to drive the optical cable tensioning seat to generate lateral displacement and cooperate with the optical cable fixing fixture to tension the test optical cable.

[0012] Furthermore, the present invention also discloses a method for testing the coupling performance between optical cables and soil, which is implemented by the aforementioned optical cable and soil coupling performance testing device; The test method for the coupling performance between optical cables and soil includes the following steps: S1. Fill the relative sliding test chamber with soil samples and lay the test optical cable through to the preset position inside the relative sliding test chamber. S2. Fix one end of the test optical cable to the optical cable fixing fixture, and connect and fix the other end of the optical cable tensioning mechanism. S3. Apply a preset pre-tension stress to the test optical cable using the optical cable tensioning mechanism and optical cable fixing fixture, and collect and store the initial strain parameters of the test optical cable. S4. Start the vertical loading mechanism to apply a constant vertical load to the soil sample in the relatively sliding test chamber. After the soil sample settles and compacts and is tightly attached to the test optical cable, the initial coupling state is established. S5. Apply graded lateral loads to the relatively sliding test chamber through the lateral loading mechanism to drive the soil sample to produce continuous lateral deformation, and simultaneously collect the actual deformation data of the soil sample and the strain response data of the test optical cable in real time. S6. Compare and analyze the actual deformation data of the soil sample with the induced deformation data of the test optical cable, calculate the deformation coupling degree and interface slip difference between the optical cable and the soil, and determine the coupling and bonding state and debonding failure characteristics of the optical cable and the soil under different load conditions based on the data change law, and complete the quantitative evaluation of the coupling performance between the optical cable and the soil.

[0013] As a further improvement to the technical solution disclosed in this invention, in step S3, the optical cable is tensioned at a uniform speed and then kept static for a preset time after being tensioned to a preset pre-tension stress value until the stress distribution and deformation state of the optical cable are stable.

[0014] As a further improvement to the technical solution disclosed in this invention, in step S5, the transverse load is applied in a stepwise gradient manner. After each level of transverse load is applied, the load is held for a preset time to allow the soil sample to undergo plastic deformation and the soil-cable interface to slip. Then, the actual deformation data of the soil sample and the strain response data of the test optical cable are collected, and the state parameters of the entire process of elastic coupling, micro-slippage, and complete debonding of the soil-cable interface are recorded.

[0015] As a further improvement to the technical solution disclosed in this invention, in step S6, based on the actual deformation data of the soil sample and the strain response data of the test optical cable, a soil deformation-optical cable strain correlation fitting model is constructed; the soil-cable deformation coupling accuracy is quantified according to the linear correlation of the fitting curve; the critical load and critical deformation amount of micro-slippage and debonding failure of the soil-cable interface are determined according to the inflection point of the curve; the deformation stages are divided according to the curve attenuation law, the soil-cable coupling attenuation characteristics of each stage are analyzed, and the layered quantitative evaluation of soil-cable coupling performance and failure mechanism determination are completed.

[0016] As a further improvement to the technical solution disclosed in this invention, a soil deformation-optical cable strain correlation fitting model is constructed through a fitting algorithm, specifically including data preprocessing, discrete point fitting, model verification and parameter calculation. Data preprocessing: Screen the valid soil deformation data and optical cable strain data collected simultaneously, remove abnormal discrete data points, and complete the data normalization and unification process; Discrete point fitting: Based on the preprocessed dataset, a linear regression fitting method is used to establish a correlation model between soil deformation and optical cable strain, and the fitting equation and fitting curve are obtained. Model validation: The model fitting accuracy is determined by the correlation coefficient of the fitted curves, and models that meet the accuracy standard are retained for coupling parameter calculation; Parameter calculation: The actual deformation of the soil sample is set as follows: The measured deformation of the optical cable was as follows: The optical cable deformation correction factor is The deformation coupling degree and the interface slip difference are calculated by fitting the model output data. The formula for calculating the deformation coupling degree is: ; The formula for calculating the interface slip difference is: ; The coupling level is classified according to the coupling degree value, and the evolution law of soil-cable interface slip is fitted according to the slip difference variation characteristics.

[0017] Regarding the topic of optical cable-soil coupling performance testing device, its practical application can achieve at least the following beneficial technical effects, specifically: 1) Relying on the lateral relative sliding characteristics of the relative sliding test chamber, it can accurately simulate the lateral progressive shear deformation state of soil in actual engineering, and simultaneously complete the vertical compaction and shaping of soil samples and the lateral continuous deformation test. It can restore the real stress and deformation conditions of soil in geotechnical engineering scenarios in multiple dimensions, effectively expanding the test simulation scenarios and the range of applicable working conditions of this device. 2) The optical cable tensioning mechanism and the optical cable fixing fixture work together to apply a constant and stable pre-tension stress to the test optical cable inserted inside the relatively sliding test chamber, ensuring that it maintains a reliable deformation coupling state with the soil sample throughout the entire test process. Furthermore, real-time deformation data of the soil sample and strain response data of the test optical cable can be collected simultaneously during the test, comprehensively recording the mechanical changes in the entire process from elastic coupling and micro-slippage to debonding failure between the test optical cable and the soil sample. This enables multi-dimensional, full-process quantitative testing of the optical cable-soil coupling performance, improving the completeness and accuracy of the test evaluation results.

[0018] Regarding the testing method for the coupling performance of optical cables and soil, this study utilizes a collaborative pretreatment approach combining pre-tensioning and shaping of the optical cable with vertical consolidation and compaction of the soil sample. This unifies the initial boundary conditions of the test, eliminates interference from non-test variables such as sample assembly, optical cable positioning, and uneven soil sample adhesion, and forms a standardized and consistent initial coupling test system. This provides a stable and unified test benchmark for deformation testing under multiple working conditions. Furthermore, the method adapts to the mechanical laws of real progressive shear deformation of soil, aligns with the complex stress conditions of actual geotechnical engineering, and relies on a synchronous data acquisition mechanism to obtain a time-series matching dataset of soil sample deformation and optical cable strain. Based on a pre-set quantitative calculation model, it accurately solves for the cable-soil coupling degree and interface slip difference. By analyzing the data evolution patterns, it distinguishes the multi-stage cable-soil interface state, fully covering the failure evolution characteristics of the entire coupling process between the optical cable and soil sample, ultimately achieving an upgrade from qualitative observation to quantitative stratified evaluation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a three-dimensional schematic diagram of the optical cable-soil coupling performance testing device disclosed in this invention.

[0021] Figure 2 This is a three-dimensional schematic diagram of the optical cable tensioning mechanism in the optical cable-soil coupling performance testing device disclosed in this invention.

[0022] Figure 3 This is a three-dimensional schematic diagram of the transverse loading mechanism in the optical cable-soil coupling performance testing device disclosed in this invention (the base is shown in the form of a double-dotted line).

[0023] Figure 4 This is a schematic diagram showing the state of the vertical loading mechanism relative to the relatively sliding test chamber after the optical cable-soil coupling performance testing device disclosed in this invention is assembled.

[0024] Figure 5 yes Figure 4 Top view.

[0025] Figure 6 yes Figure 5 AA sectional view.

[0026] Figure 7 yes Figure 1 The enlarged view of part I shows the assembly structure of the relative sliding test chamber.

[0027] Figure 8 This is a physical image of the optical cable-soil coupling performance testing device disclosed in this invention.

[0028] Figure 9 This is a strain curve distribution diagram of a test scenario for the optical cable-soil coupling performance testing method disclosed in this invention.

[0029] 1-Base; 2-Optical cable tensioning mechanism; 21-Optical cable tensioning seat; 22-Linear drive component; 23-Tensioning reaction frame; 3-Transverse loading mechanism; 31-Left loading fixture; 32-Right loading fixture; 4-Vertical loading mechanism; 41-Left vertical loading sub-mechanism; 42-Right vertical loading sub-mechanism; 5-Relative sliding test chamber; 51-Main chamber; 52-Embedded chamber; 6-Optical cable fixing fixture. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to specific embodiments. Figure 1 , Figure 8 The diagram shows the structure of the optical cable-soil coupling performance testing device disclosed in this invention. It is evident that it mainly consists of a base 1, an optical cable tensioning mechanism 2, a transverse loading mechanism 3, a vertical loading mechanism 4, a relative sliding test chamber 5, and an optical cable fixing fixture 6. The optical cable tensioning mechanism 2, the transverse loading mechanism 3, the relative sliding test chamber 5, and the optical cable fixing fixture 6 are all fixed to the base 1, and the vertical loading mechanism 4 is correspondingly installed on the top wall of the relative sliding test chamber 5, working together to complete the simulation, loading, data acquisition, and quantitative testing of the optical cable-soil coupling performance.

[0031] The relative sliding test chamber 5 serves as a functional component for accommodating soil samples and simulating transverse shear deformation, such as... Figure 7 As shown, it includes a main chamber 51 and an inner chamber 52 that are nested together and can slide relative to each other in a controlled lateral direction. The main chamber 51 and the inner chamber 52 adopt a nested fit structure to provide a closed and complete containment space for the soil sample, and can generate relative displacement in a set direction under lateral load to reproduce the lateral progressive shear deformation state of soil under load in geotechnical engineering scenarios. The test optical cable is laid through and extended to the internal center of the relative sliding test chamber 5, and is completely and uniformly wrapped by the soil sample to ensure that the test optical cable and the soil sample can fully contact and deform together, laying a good foundation for subsequent strain response data acquisition.

[0032] To ensure that the test optical cable and soil sample maintain a stable deformation synergy throughout the entire testing process, the optical cable tensioning mechanism 2, as a key component for applying pre-tension stress to the test optical cable and ensuring the cable-soil deformation coupling effect, such as... Figure 2 As shown, it includes an optical cable tensioning seat 21, a linear drive component 22, and a tensioning reaction frame 23. The tensioning reaction frame 23 is fixedly installed on the base 1 to provide rigid support for the tensioning operation; the linear drive component 22 is used to drive the optical cable tensioning seat 21 to produce a smooth and uniform lateral displacement; the optical cable tensioning mechanism 2 and the optical cable fixing fixture 6 are arranged in a straight line facing each other. The two work together to apply a constant pre-tension stress to the test optical cable, and after being tensioned at a uniform speed to the preset stress value, it is stabilized and left to stand for a preset time until the stress distribution of the test optical cable is uniform and the deformation state is completely stable, thus completely eliminating adverse factors such as initial slack and bending of the optical cable.

[0033] After the test optical cable has been pre-tightened and shaped, a controllable lateral load needs to be applied to the soil sample to simulate real shear deformation conditions. The lateral loading mechanism 3 acts as the actuator that drives the relative sliding test chamber 5 to generate relative displacement, causing the soil sample to undergo lateral shear deformation. Figure 3As shown, it consists of a left loading fixture 31 and a right loading fixture 32 located on the left and right sides of the relative sliding test chamber 5. The left loading fixture 31 is matched with the main chamber 51, and the right loading fixture 32 is matched with the embedded chamber 52. They can output lateral loads independently or in concert to drive the main chamber 51 and the embedded chamber 52 to produce graded and controllable relative sliding in the lateral direction, thereby applying a gradient increasing lateral load to the soil sample inside the relative sliding test chamber 5, causing the soil sample to produce continuous and uniform lateral shear deformation.

[0034] Furthermore, transverse shear deformation testing requires a uniform and dense soil condition. The vertical loading mechanism 4 serves as a functional component that applies vertical loads to the soil sample, completing the soil consolidation and compaction. For example... Figures 4-7 As shown, the vertical loading mechanism 4 consists of a left-side vertical loading sub-mechanism 41 and a right-side vertical loading sub-mechanism 42. The left-side vertical loading sub-mechanism 41 corresponds to and cooperates with the main chamber 51, and the right-side vertical loading sub-mechanism 42 corresponds to and cooperates with the embedded chamber 52. They can synchronously output constant vertical pressure to apply uniform vertical loads to the soil samples inside the main chamber 51 and the embedded chamber 52, respectively, so that the soil samples settle and compact quickly and fit tightly with the test optical cable.

[0035] In practical applications, relying on the lateral relative sliding structure of the relative sliding test chamber, the device simulates the lateral progressive shear deformation state of soil, simultaneously completing the vertical compaction and shaping of soil samples and the lateral continuous deformation test. This recreates the real stress and deformation conditions of soil under geotechnical engineering scenarios, expanding the testing scenarios and adaptability of the device. Furthermore, the optical cable tensioning mechanism and the optical cable fixing fixture work together to apply a constant and stable pre-stress to the test optical cable, ensuring the deformation coupling effect between the optical cable and the soil throughout the test process. Simultaneously, soil deformation and optical cable strain data are collected, comprehensively recording the mechanical changes throughout the entire soil-cable coupling process.

[0036] This invention also discloses a method for testing the coupling performance of optical cables to soil, which is implemented using the aforementioned optical cable-soil coupling performance testing device, and specifically includes the following testing steps: S1. Soil samples are filled into the relative sliding test chamber 5 in layers, and the test optical cable is laid through the central axis of the chamber to the preset calibration position inside the relative sliding test chamber 5. S2. Fix one end of the test optical cable to the optical cable fixing fixture 6, and fix the other end of the test optical cable to the optical cable tensioning seat 21 of the optical cable tensioning mechanism 2 to complete the rigid positioning of both ends of the test optical cable. S3. Apply a preset pre-tension stress to the test optical cable through the optical cable tensioning mechanism 2 and the optical cable fixing fixture 6. Complete the tensioning operation in a uniform manner. After tensioning to the preset pre-tension stress value, stabilize the pressure and let it stand for a preset time until the stress distribution of the test optical cable is uniform and the deformation state is completely stable. Collect and store the initial strain parameters of the test optical cable to establish a standardized initial test benchmark. S4. Start the vertical loading mechanism 4, and apply a constant vertical load to the soil sample inside the relatively sliding test chamber 5 through the left vertical loading sub-mechanism 41 and the right vertical loading sub-mechanism 42. Continue loading until the soil sample settles and becomes compacted and tightly attached to the test optical cable, thus completing the establishment of the initial coupling state of the test. S5. Apply progressively increasing graded lateral loads to the relative sliding test chamber 5 through the lateral loading mechanism 3, driving the main chamber 51 and the embedded chamber 52 to slide relative to each other, causing the soil sample to undergo continuous lateral shear deformation. After each lateral load is applied, hold the pressure and stand still for a preset time. After the plastic deformation of the soil sample has fully developed and the slip state of the soil-cable interface has stabilized, simultaneously collect the actual deformation data of the soil sample and the strain response data of the test optical cable in real time, and record the state parameters of the entire process of elastic coupling, micro-slippage and complete debonding of the soil-cable interface. S6. Compare and analyze the actual deformation data of the soil sample with the induced deformation data of the test optical cable, calculate the deformation coupling degree and interface slip difference between the optical cable and the soil, and determine the coupling and bonding state and debonding failure characteristics of the optical cable and the soil under different load conditions based on the data change law, and complete the quantitative evaluation of the coupling performance between the optical cable and the soil. The actual deformation of the soil sample is set as follows: The measured deformation of the optical cable was as follows: The optical cable deformation correction factor is The deformation coupling degree and the interface slip difference are calculated by fitting the model output data. The formula for calculating the deformation coupling degree is: ; The formula for calculating the interface slip difference is: ; The coupling level is classified according to the coupling degree value, and the evolution law of soil-cable interface slip is fitted according to the slip difference variation characteristics.

[0037] Figure 9 The diagram shows the strain curve distribution of a test scenario in the optical cable-soil coupling performance testing method disclosed in this invention. It clearly presents the corresponding change law of soil deformation and optical cable strain, and can intuitively distinguish the curve characteristics of the three key stages of elastic coupling, micro-slippage and complete debonding, providing intuitive data support for coupling performance determination and failure mechanism analysis.

[0038] In summary, a pretreatment method combining pre-tensioning and shaping of the optical cable with vertical consolidation and compaction of the soil sample was adopted. This unified the initial boundary conditions, eliminated interference from non-experimental variables, and formed a standardized initial coupling test system, providing a stable and unified test benchmark for multi-condition testing. Furthermore, the testing process closely follows the actual progressive shear deformation mechanics of soil and the actual stress conditions in geotechnical engineering. Relying on a synchronous data acquisition mechanism throughout the entire process, time-matched test data was obtained. Coupling parameters were accurately solved through a quantitative calculation model, distinguishing the multi-stage states of the soil-cable interface and fully covering the evolution characteristics of soil-cable coupling failure. This achieved a transformation from qualitative observation to quantitative, layered evaluation of the coupling performance between the optical cable and soil.

[0039] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for testing the coupling performance of optical cables to soil, characterized in that, It includes a base, an optical cable tensioning mechanism, a lateral loading mechanism, a vertical loading mechanism, a relative sliding test chamber, and optical cable fixing fixtures; The optical cable tensioning mechanism, the transverse loading mechanism, the relative sliding test chamber, and the optical cable fixing fixture are all installed and fixed on the base; The relative sliding test chamber is used to hold soil samples; The vertical loading mechanism is installed on the top wall of the relative sliding test chamber and is used to apply a vertical load to the soil sample inside the relative sliding test chamber. The lateral loading component is used to apply a lateral load to the test chamber component, causing the soil sample to undergo lateral deformation. The test optical cable is inserted inside the relative slip test chamber and wrapped by the soil sample; the optical cable tensioning mechanism and the optical cable fixing fixture are arranged opposite to each other, and the two work together to apply pre-tension stress to the test optical cable and keep the test optical cable and the soil sample deformably coupled.

2. The optical cable-soil coupling performance testing device according to claim 1, characterized in that, The relative sliding test chamber includes a main chamber and an embedded chamber that are nested together and slide relative to each other in the lateral direction.

3. The optical cable-soil coupling performance testing device according to claim 2, characterized in that, The lateral loading mechanism consists of a left loading fixture and a right loading fixture; the left loading fixture and the right loading fixture are respectively matched with the main chamber and the embedded chamber to drive them to slide relative to each other in the lateral direction.

4. The optical cable-soil coupling performance testing device according to claim 2, characterized in that, The vertical loading mechanism comprises a left-side vertical loading sub-mechanism and a right-side vertical loading sub-mechanism; the left-side vertical loading sub-mechanism and the right-side vertical loading sub-mechanism are respectively matched with the main chamber and the embedded chamber, and are used to apply vertical loads to the soil samples in both chambers.

5. The optical cable-soil coupling performance testing device according to claim 1, characterized in that, The optical cable tensioning mechanism includes an optical cable tensioning seat, a linear drive component, and a tensioning reaction frame; the tensioning reaction frame is fixed to the base; the drive component is used to drive the optical cable tensioning seat to generate lateral displacement, and cooperates with the optical cable fixing fixture to tension the test optical cable.

6. A method for testing the coupling performance between optical cable and soil, characterized in that, This is achieved by the optical cable-soil coupling performance testing device as described in any one of claims 1-5; The test method for the coupling performance between optical cables and soil includes the following steps: S1. Fill the relative sliding test chamber with soil samples and lay the test optical cable through it to a preset position inside the relative sliding test chamber. S2. Fix one end of the test optical cable to the optical cable fixing fixture, and connect and fix the other end of the optical cable tensioning mechanism. S3. Apply a preset pre-tension stress to the test optical cable through the optical cable tensioning mechanism in conjunction with the optical cable fixing fixture, and collect and store the initial strain parameters of the test optical cable. S4. Activate the vertical loading mechanism to apply a constant vertical load to the soil sample in the relative sliding test chamber. After the soil sample settles and compacts and is tightly attached to the test optical cable, the initial coupling state is established. S5. Apply graded lateral loads to the relatively sliding test chamber through the lateral loading mechanism to drive the soil sample to produce continuous lateral deformation, and simultaneously collect the actual deformation data of the soil sample and the strain response data of the test optical cable in real time. S6. Compare and analyze the actual deformation data of the soil sample with the induced deformation data of the test optical cable, calculate the deformation coupling degree and interface slip difference between the optical cable and the soil, and determine the coupling and bonding state and debonding failure characteristics of the optical cable and the soil under different load conditions based on the data change law, and complete the quantitative evaluation of the coupling performance between the optical cable and the soil.

7. The method for testing the coupling performance between optical cable and soil according to claim 6, characterized in that, In step S3, the optical cable is tensioned at a constant speed until it reaches the preset pre-tension stress value. After tensioning, it is kept static for a preset time until the stress distribution and deformation state of the optical cable are stable.

8. The method for testing the coupling performance between optical cable and soil according to claim 6, characterized in that, In step S5, the transverse load is applied in a stepwise gradient manner. After each level of transverse load is applied, the load is held for a preset time to allow the soil sample to undergo plastic deformation and the soil-cable interface to slip. Then, the actual deformation data of the soil sample and the strain response data of the test optical cable are collected, and the state parameters of the entire process of elastic coupling, micro-slippage, and complete debonding of the soil-cable interface are recorded.

9. The method for testing the coupling performance between optical cable and soil according to claim 6, characterized in that, In step S6, based on the actual deformation data of the soil sample and the strain response data of the test optical cable acquired synchronously, a soil deformation-optical cable strain correlation fitting model is constructed; the soil-optical cable deformation coupling accuracy is quantified according to the linear correlation of the fitting curve. The critical load and critical deformation amount for micro-slippage and debonding failure at the soil-cable interface are determined based on the inflection point of the curve; the deformation stages are divided according to the attenuation law of the curve, the coupling attenuation characteristics of the soil-cable at each stage are analyzed, and the layered quantitative evaluation of the coupling performance of the soil-cable and the determination of the failure mechanism are completed.

10. The method for testing the coupling performance between optical cable and soil according to claim 9, characterized in that, A soil deformation-optical cable strain correlation fitting model was constructed using a fitting algorithm, which included data preprocessing, discrete point fitting, model validation, and parameter calculation. Data preprocessing: Screening the valid soil deformation data and optical cable strain data collected simultaneously, removing abnormal discrete data points, and completing the data normalization and unification process; Discrete point fitting: Based on the preprocessed dataset, a linear regression fitting method is used to establish a correlation model between soil deformation and optical cable strain, and the fitting equation and fitting curve are obtained. Model validation: The model fitting accuracy is determined by the correlation coefficient of the fitted curves, and models that meet the accuracy standard are retained for coupling parameter calculation; Parameter calculation: The actual deformation of the soil sample is set as follows: The measured deformation of the optical cable was as follows: The optical cable deformation correction factor is The deformation coupling degree and the interface slip difference are calculated by fitting the model output data; The formula for calculating the deformation coupling degree is: ; The formula for calculating the interface slip difference is: ; The coupling level is classified according to the coupling degree value, and the evolution law of soil-cable interface slip is fitted according to the slip difference variation characteristics.

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