Anchor cable corrosion strength degradation detection method and system based on current density time-varying effect

Abstract

The present application relates to the technical field of coal mine support, and provides a method and system for detecting the corrosion strength degradation of anchor cables based on the time-varying effect of current density. The method includes: constructing a chloride ion diffusion coefficient model of the grouting anchor cable that changes with temperature based on the acquired tunnel working surface temperature to determine the chloride ion diffusion coefficient on the surface of the grouting anchor cable; constructing a first current density time-varying model of the grouting anchor cable based on the chloride ion diffusion coefficient on the surface of the grouting anchor cable and the acquired chloride ion concentration on the surface of the grouting anchor cable; constructing a second current density time-varying model of the grouting anchor cable that changes with time based on the chloride ion diffusion coefficient and the first current density time-varying model; constructing a corrosion strength degradation time-varying model of the grouting anchor cable based on the second current density time-varying model and the physical parameters of the grouting anchor cable to determine the existing maximum bearing capacity of the grouting anchor cable; determining the support risk of the grouting anchor cable based on the existing maximum bearing capacity of the grouting anchor cable and the preset support failure threshold.

Description

Technical Field

[0001] The present application relates to the field of coal mine support technology, and in particular to a method and system for detecting anchor cable corrosion strength degradation based on the time-varying effect of current density. Background Art

[0002] With the increasing demand for coal resources, deep mining is still the mainstream trend of coal mining at this stage. Grouting anchor is the main support method for deep mining. With the further increase of mining depth (800-1000 meters), the complex deep environment has more and more stringent requirements on the support strength of grouting anchor.

[0003] As the main support means for deep mining, the strength degradation and failure of grouting anchor cables are becoming increasingly serious, and corrosion is the main cause of anchor cable strength degradation. Affected by multiple factors in the service environment and their mutual coupling, the strength degradation of grouting anchor cables induced by corrosion seriously affects the service life of the support structure, destroys the stability of the construction structure, and then causes mining disasters, resulting in human and property losses.

[0004] Therefore, there is an urgent need to provide a technical solution to the above-mentioned deficiencies in the prior art. Summary of the invention

[0005] The purpose of the present application is to provide a method and system for detecting anchor cable corrosion strength degradation based on the time-varying effect of current density, so as to solve or alleviate the problems existing in the above-mentioned prior art.

[0006] In order to achieve the above objectives, this application provides the following technical solutions:

[0007] The present application provides a method for detecting the corrosion strength degradation of an anchor cable based on the time-varying effect of current density, comprising: step S101, constructing a chloride ion diffusion coefficient model of the grouting anchor cable that varies with temperature based on the acquired tunnel working surface temperature, so as to determine the chloride ion diffusion coefficient on the surface of the grouting anchor cable; step S102, constructing a first current density time-varying model of the grouting anchor cable according to the chloride ion diffusion coefficient on the surface of the grouting anchor cable and the acquired chloride ion concentration on the surface of the grouting anchor cable; step S103, constructing a second current density time-varying model of the grouting anchor cable that varies with time based on the chloride ion diffusion coefficient and the first current density time-varying model; step S104, constructing a corrosion strength degradation time-varying model of the grouting anchor cable based on the second current density time-varying model and the physical parameters of the grouting anchor cable, so as to determine the existing maximum bearing capacity of the grouting anchor cable; step S105, determining the support risk of the grouting anchor cable according to a preset support failure threshold based on the existing maximum bearing capacity of the grouting anchor cable.

[0008] Preferably, in step S101, the chloride ion diffusion coefficient model of the grouting anchor cable changing with temperature is:

[0009]

[0010] Wherein, D is the chloride ion diffusion coefficient on the surface of the grouting anchor cable; T0 is the surface temperature of the grouting anchor cable at room temperature; T is the surface temperature of the grouting anchor cable under service state; D0 is the effective diffusion coefficient of chloride ions in the underground surrounding rock in contact with the grouting anchor cable at room temperature; q is the activation constant value.

[0011] Preferably, in step S102, the first current density time-varying model is:

[0012]

[0013] Wherein, i1(t) is the corrosion current density of the grouting anchor cable at time t; C s is the chloride ion concentration on the surface of the grouting anchor cable; C0 is the chloride ion concentration on the surface of the grouting body; D is the chloride ion diffusion coefficient on the surface of the grouting anchor cable; T is the surface temperature of the grouting anchor cable in the service state; R is the resistivity of the underground surrounding rock in contact with the grouting anchor cable; x is the existing thickness of the surface grouting body of the grouting anchor cable.

[0014] Preferably, in step S103, the second current density time-varying model is:

[0015]

[0016] Wherein, i(t) is the corrosion current density of the grouting anchor cable changing with time t; C0 is the chloride ion concentration on the surface of the underground surrounding rock in contact with the grouting anchor cable; x is the existing thickness of the surface grouting body of the grouting anchor cable; D is the chloride ion diffusion coefficient on the surface of the grouting anchor cable; T is the surface temperature of the grouting anchor cable in the service state; R is the resistivity of the underground surrounding rock in contact with the grouting anchor cable.

[0017] Preferably, in step S104, according to the formula:

[0018]

[0019] Determine the real-time corrosion rate v of the grouting anchor cable r ; Among them, M Fe is the relative atomic mass of the material of the grouting anchor cable; i(t) is the corrosion current density of the grouting anchor cable changing with time t; n Fe is the number of electrons lost by the material of the grouting anchor cable; Fe is the density of the material of the grouting anchor cable.

[0020] Preferably, in step S104, the time-varying model of corrosion strength degradation of the grouting anchor cable is:

[0021]

[0022] Among them, f Fe is the existing maximum bearing capacity of the grouting anchor cable; σ is the ultimate tensile strength of the grouting anchor cable; r0 is the equivalent initial radius of the grouting anchor cable; M Fe is the relative atomic mass of the material of the grouting anchor cable; i(t) is the corrosion current density of the grouting anchor cable changing with time t; n Fe is the number of electrons lost by the material of the grouting anchor cable; Fe is the density of the material of the grouting anchor cable.

[0023] Preferably, in step S105, the existing maximum bearing capacity f of the grouting anchor cable is Fe and the preset support failure threshold f s A comparison is performed to determine the support failure risk of the grouting anchor cable.

[0024] Preferably, according to the formula:

[0025] f s ={0.92f0, 0.88f0, 0.85f0}

[0026] Determine the support failure threshold f corresponding to different support failure risks s ; Wherein, f0 is the maximum initial bearing capacity of the grouting anchor cable.

[0027] The embodiment of the present application also provides a system for detecting anchor cable corrosion strength degradation based on the time-varying effect of current density, comprising:

[0028] The chloride ion diffusion model is configured to construct a chloride ion diffusion coefficient model of the grouting anchor cable that varies with temperature based on the acquired tunnel working face temperature, so as to determine the chloride ion diffusion coefficient on the surface of the grouting anchor cable; the first time-varying model is configured to construct a first current density time-varying model of the grouting anchor cable according to the chloride ion diffusion coefficient on the surface of the grouting anchor cable and the acquired chloride ion concentration on the surface of the grouting anchor cable; the second time-varying model is configured to construct a second current density time-varying model of the grouting anchor cable that varies with time based on the chloride ion diffusion coefficient and the first current density time-varying model; the corrosion calculation unit is configured to construct a corrosion strength degradation time-varying model of the grouting anchor cable based on the second current density time-varying model and the physical parameters of the grouting anchor cable, so as to determine the existing maximum bearing capacity of the grouting anchor cable; the risk judgment model is configured to determine the support failure risk of the grouting anchor cable according to a preset support failure threshold based on the existing maximum bearing capacity of the grouting anchor cable.

[0029] Beneficial effects:

[0030] In the anchor cable corrosion strength degradation detection method based on the current density time-varying effect provided in the embodiment of the present application, first, based on the acquired tunnel working surface temperature, a chloride ion diffusion coefficient model of the grouting anchor cable that changes with temperature is constructed to determine the chloride ion diffusion coefficient on the surface of the grouting anchor cable; then, according to the chloride ion diffusion coefficient on the surface of the grouting anchor cable and the acquired chloride ion concentration on the surface of the grouting anchor cable that supports the tunnel, a first current density time-varying model of the grouting anchor cable is constructed; then, according to the chloride ion diffusion coefficient and the first current density time-varying model, a second current density time-varying model of the grouting anchor cable that changes with time is constructed; further, according to the second current density time-varying model and the physical parameters of the grouting anchor cable, a corrosion strength degradation time-varying model of the grouting anchor cable is constructed to determine the existing maximum bearing capacity of the grouting anchor cable; finally, based on the existing maximum bearing capacity of the grouting anchor cable, the support risk of the grouting anchor cable is determined according to the preset support failure threshold.

[0031] Based on this, the chloride ion concentration on the surface of the grouting anchor is obtained by the chloride ion diffusion coefficient model, and a first current density time-varying model based on the chloride ion concentration is constructed. The chloride ion diffusion coefficient is used to characterize the changes of the chloride ion concentration on the surface of the grouting anchor with time and temperature, and a second current density time-varying model of the grouting anchor with changes in chloride ion concentration, temperature and time is constructed. Then, the changes of the grouting anchor with chloride ion concentration, temperature and time are combined with the current density to describe the corrosion changes of the grouting anchor, and the existing maximum bearing capacity of the grouting anchor is calculated, that is, the real-time strength of the grouting anchor on the working face of the target coal mine tunnel, so as to accurately monitor the service life of the grouting anchor support structure, and effectively prevent mine disasters caused by the destruction of the stability of the construction structure, resulting in human and property losses; at the same time, the corrosion monitoring theory of the grouting anchor on the working face of the coal mine tunnel is improved to ensure the safe and efficient production of the underground working face. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. Among them:

[0033] Figure 1 A schematic flow chart of a method for detecting anchor cable corrosion strength degradation based on the time-varying effect of current density according to some embodiments of the present application;

[0034] Figure 2 A schematic diagram of a process of corrosion of a grouting anchor cable caused by chloride ion diffusion according to some embodiments of the present application;

[0035] Figure 3A schematic diagram of corrosion on the surface of a grouting anchor cable provided according to some embodiments of the present application;

[0036] Figure 4 A schematic structural diagram of an anchor cable corrosion strength degradation detection system based on the time-varying effect of current density provided according to some embodiments of the present application. DETAILED DESCRIPTION

[0037] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present application and does not limit the present application. In fact, it will be clear to those skilled in the art that modifications and variations may be made in the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as a part of an embodiment may be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the embodiments of the present invention should belong to the scope of protection of the embodiments of the present invention.

[0038] At present, the system for detecting grouting anchor cable corrosion is still imperfect, especially the problem of shortening the effective support radius of grouting anchor cable support due to the influence of multiple factors in the service environment and their mutual coupling needs to be further explored. Based on this, the embodiment of the present application proposes a method for detecting the corrosion strength degradation of grouting anchor cables based on the time-varying effect of current density, so as to effectively solve the problem of real-time detection of the corrosion strength of grouting anchor cables, timely monitor the effective support strength of grouting anchor cables, and maintain the safety of coal mine tunnel support, which is of great significance.

[0039] like Figure 1 As shown, the anchor cable corrosion strength degradation detection method based on the time-varying effect of current density includes:

[0040] Step S101: Based on the acquired tunnel working surface temperature, a chloride ion diffusion coefficient model of the grouting anchor cable that changes with temperature is constructed to determine the chloride ion diffusion coefficient on the surface of the grouting anchor cable.

[0041] In this application, the geological mining data of the coal mine tunnel working face where the grouting anchor cable is located is obtained. Among them, for the tunnel working face to be tested, the coal seam occurrence conditions, coal mining methods, geological structure and support design, working face layout details, model parameters of the grouting anchor cable used, chloride ion concentration on the surface of the grouting anchor cable (the range of rock layers contacted by the anchor cable corrosion, generally within 10 meters of rock layer thickness), tunnel working face temperature and other mine geological and mining data are obtained.

[0042] When the chloride ion concentration on the surface of the grouting anchor cable in the underground rock formation reaches a certain level, corrosion will occur due to the destruction of the passivation film. Moreover, the diffusion and penetration rate of chloride ions is very fast, and they can reach the material surface of the grouting anchor cable in a very short time, accelerating the corrosion of the grouting anchor cable. At the same time, the high geothermal environment of deep mines also causes the anchoring performance of the grouting anchor cable to be seriously affected, and linear anchor failure occurs from time to time. Under the action of high temperature, the corrosion rate of the grouting anchor cable will increase with the increase of temperature, and the chloride ions will become more active with the increase of temperature, exacerbating the diffusion of chloride ions. Therefore, in the present application, in the analysis of the grouting anchor cable, the main factors affecting the corrosion rate are the chloride ion concentration and the working surface temperature of the tunnel.

[0043] After obtaining the temperature change of the tunnel working face through geological mining, a chloride ion diffusion coefficient model based on temperature change on the surface of the grouting anchor cable is constructed. Specifically, the chloride ion diffusion coefficient model of the grouting anchor cable surface with temperature change is:

[0044]

[0045] Where D is the chloride ion diffusion coefficient on the surface of the grouting anchor cable; T0 is the surface temperature of the grouting anchor cable at room temperature; T is the surface temperature of the grouting anchor cable under service; D0 is the effective diffusion coefficient of chloride ions in the surrounding rock in contact with the grouting anchor cable at room temperature (surface temperature T0 of the grouting anchor cable), which is a constant (D0 = 2.25 × 10 13 m 2 / s); q is the activation constant value, which is 1.

[0046] Step S102: constructing a first current density time-varying model of the grouting anchor cable according to the chloride ion diffusion coefficient on the surface of the grouting anchor cable and the acquired chloride ion concentration on the surface of the grouting anchor cable.

[0047] The chloride ion diffusion coefficient on the surface of the grouting anchor cable is obtained through the chloride ion diffusion coefficient model that changes with temperature. Combined with the chloride ion concentration on the surface of the grouting anchor cable obtained by geological mining, a current density time-varying model based on the chloride ion concentration on the surface of the grouting anchor cable is constructed, namely the first current density time-varying model. Specifically, the first current density time-varying model is:

[0048]

[0049] Where i1(t) is the corrosion current density of the grouting anchor at time t; C sis the chloride ion concentration on the surface of the grouting anchor; C0 is the chloride ion concentration on the surface of the grouting body (concrete); D is the chloride ion diffusion coefficient on the surface of the grouting anchor; T is the surface temperature of the grouting anchor in the service state; R is the resistivity of the underground surrounding rock in contact with the grouting anchor (inner wall of the borehole); x is the existing thickness of the surface grouting body (cement grouting) of the grouting anchor.

[0050] Step S103: construct a second current density time-varying model of the grouting anchor cable that varies with time based on the chloride ion diffusion coefficient and the first current density time-varying model.

[0051] The present applicants characterized the change of chloride ion concentration on the surface of grouting anchor with time and temperature by chloride ion diffusion coefficient, combined with chloride ion diffusion coefficient and current density time-varying model based on chloride ion concentration on the surface of grouting anchor, constructed a second current density time-varying model of grouting anchor with change of chloride ion concentration, temperature and time.

[0052] Specifically, the second current density time-varying model is:

[0053]

[0054] Where i(t) is the corrosion current density of the grouting anchor cable changing with time t; C0 is the chloride ion concentration on the surface of the underground surrounding rock in contact with the grouting anchor cable; x is the existing thickness of the surface grouting body of the grouting anchor cable; D is the chloride ion diffusion coefficient on the surface of the grouting anchor cable; T is the surface temperature of the grouting anchor cable in service; R is the resistivity of the underground surrounding rock in contact with the grouting anchor cable.

[0055] Step S104: Based on the second current density time-varying model and the physical parameters of the grouting anchor cable, a corrosion strength degradation time-varying model of the grouting anchor cable is constructed to determine the existing maximum bearing capacity of the grouting anchor cable.

[0056] like Figure 2 As shown in the figure, the grouting anchor cables, under the influence of multiple factors in the service environment and their mutual coupling, rust occurs, inducing the strength degradation of the grouting anchor cables and shortening the effective support radius of the grouting anchor cables, which seriously affects the adaptability life of the support structure, destroys the stability of the construction structure, and leads to mine disasters.

[0057] Therefore, in the present application, the chloride ion concentration, temperature, other field concentrations (such as oxygen concentration) on the surface of the grouting anchor are comprehensively considered to change with time, the real-time corrosion of the grouting anchor is analyzed, and a time-varying model of the corrosion strength degradation of the grouting anchor is constructed to determine the current maximum bearing capacity of the grouting anchor.

[0058] In this application, if Figure 3 As shown in the figure, during the rusting process of the grouting anchor cable, the surface of the grouting anchor cable corrodes uniformly, according to the formula:

[0059]

[0060] Determine the real-time corrosion rate v of the grouting anchor r Among them, M Fe is the relative atomic mass of the material of the grouting anchor cable; i(t) is the corrosion current density of the grouting anchor cable changing with time t; n Fe is the number of electron loss of the material of the grouting anchor cable; ρ Fe is the density of the material of the grouting anchor.

[0061] Furthermore, during the corrosion process of the grouting anchor cable, the diameter of the grouting anchor cable gradually decreases with time. Specifically, according to the formula:

[0062]

[0063] Determine the surface loss thickness r1 of the grouting anchor cable; where v r is the corrosion rate of the grouting anchor surface.

[0064] Correspondingly, the real-time cross-sectional area of ​​the grouting anchor cable during the corrosion process is:

[0065]

[0066] That is, the real-time cross-sectional area of ​​the grouting anchor at time t.

[0067] Finally, according to the ultimate tensile strength of the grouting anchor and the real-time cross-sectional area S of the grouting anchor during the corrosion process, Fe , determine the existing maximum bearing capacity of the grouting anchor cable. That is, according to the formula:

[0068]

[0069] Determine the maximum existing bearing capacity of the grouting anchor cable. Fe is the existing maximum bearing capacity of the grouting anchor cable; σ is the ultimate tensile strength of the grouting anchor cable; r0 is the equivalent initial radius of the grouting anchor cable; M Fe is the relative atomic mass of the material of the grouting anchor cable; i(t) is the corrosion current density of the grouting anchor cable changing with time t; n Fe is the number of electron loss of the material of the grouting anchor cable; ρ Fe is the density of the material of the grouting anchor.

[0070] Step S105: Based on the existing maximum bearing capacity of the grouting anchor cable and in accordance with a preset support failure threshold, determine the support risk of the grouting anchor cable.

[0071] In this application, the maximum bearing capacity f of the grouting anchor cable is obtained by using the time-varying model of corrosion strength degradation of the grouting anchor cable. FeAfter that, the existing maximum bearing capacity of the grouting anchor cable f Fe and the preset support failure threshold f s Compare and determine the support failure risk of grouting anchor cables. According to the formula:

[0072] f s ={0.92f0, 0.88f0, 0.85f0}

[0073] Determine the support failure threshold f corresponding to different support failure risks s ; where f0 is the maximum initial bearing capacity of the grouting anchor cable. Specifically, when f Fe >f s =0.92f0, there is no risk of support failure in the tunnel; when f s =0.88f0 <f Fe ≤f s =0.92f0, the tunnel has the risk of weak support failure; when f s =0.85f0 <f Fe ≤f s =0.88f0, the tunnel has medium support risk; when f Fe ≤f s When =0.85f0, the tunnel is at risk of strong support failure.

[0074] In this application, a first current density time-varying model is constructed based on the chloride ion concentration on the surface of the grouting anchor cable, and a second current density time-varying model is constructed based on the chloride ion diffusion coefficient model based on temperature change to quickly and accurately identify the change in current density on the surface of the grouting anchor cable. The surface loss thickness, cross-sectional area, and maximum bearing capacity of the grouting anchor cable are monitored in real time, and the real-time strength of the grouting anchor cable on the working surface of the target coal mine tunnel is obtained, and the service life of the grouting anchor cable support structure is accurately monitored, effectively preventing mining disasters caused by the destruction of the stability of the construction structure, resulting in human and property losses. At the same time, the theory of grouting anchor cable corrosion monitoring on the working surface of the coal mine tunnel is improved to ensure the safe and efficient production of the underground working surface.

[0075] like Figure 4 As shown, the embodiment of the present application also provides an anchor cable corrosion strength degradation detection system based on the time-varying effect of current density, comprising:

[0076] The chloride ion diffusion model 401 is configured to construct a chloride ion diffusion coefficient model of the grouting anchor cable with temperature change based on the acquired tunnel working surface temperature, so as to determine the chloride ion diffusion coefficient on the surface of the grouting anchor cable;

[0077] The first time-varying model 402 is configured to construct a first current density time-varying model of the grouting anchor cable according to the chloride ion diffusion coefficient on the surface of the grouting anchor cable and the acquired chloride ion concentration on the surface of the grouting anchor cable;

[0078] The second time-varying model 403 is configured to construct a second current density time-varying model of the grouting anchor cable that varies with time according to the chloride ion diffusion coefficient and the first current density time-varying model;

[0079] The corrosion calculation unit 404 is configured to construct a corrosion strength degradation time-varying model of the grouting anchor cable based on the second current density time-varying model and the physical parameters of the grouting anchor cable to determine the existing maximum bearing capacity of the grouting anchor cable;

[0080] The risk judgment model 405 is configured to determine the support failure risk of the grouting anchor cable based on the existing maximum bearing capacity of the grouting anchor cable and according to a preset support failure threshold.

[0081] The anchor cable corrosion strength degradation detection system based on the time-varying effect of current density provided in the embodiment of the present application can implement the steps and processes of the anchor cable corrosion strength degradation detection method based on the time-varying effect of current density described in any of the above embodiments, and achieve the same technical effects, which will not be repeated here one by one.

[0082] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0083] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0084] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for detecting anchor cable corrosion strength degradation based on the time-varying effect of current density, characterized in that: include: Step S101, based on the acquired tunnel working surface temperature, constructing a chloride ion diffusion coefficient model of the grouting anchor cable that changes with temperature to determine the chloride ion diffusion coefficient on the surface of the grouting anchor cable; Step S102: construct a first current density time-varying model of the grouting anchor cable according to the chloride ion diffusion coefficient on the surface of the grouting anchor cable and the chloride ion concentration on the surface of the grouting anchor cable obtained; wherein the first current density time-varying model is: ； In the formula, The grouting anchor cable is at time The corrosion current density of is the chloride ion concentration on the surface of the grouting anchor cable; is the chloride ion concentration on the surface of the grouting body; is the chloride ion diffusion coefficient on the surface of the grouting anchor cable; is the surface temperature of the grouting anchor cable in the service state; is the resistivity of the underground surrounding rock in contact with the grouting anchor cable; is the existing thickness of the surface grouting body of the grouting anchor cable; Step S103, constructing a second current density time-varying model of the grouting anchor cable that changes with time according to the chloride ion diffusion coefficient and the first current density time-varying model; wherein the second current density time-varying model is: ； in, The grouting anchor cable Changing corrosion current density; Step S104: constructing a corrosion strength degradation time-varying model of the grouting anchor cable based on the second current density time-varying model and the physical parameters of the grouting anchor cable to determine the existing maximum bearing capacity of the grouting anchor cable; Step S105: Based on the existing maximum bearing capacity of the grouting anchor cable and in accordance with a preset support failure threshold, determine the support risk of the grouting anchor cable.

2. The anchor cable corrosion strength degradation detection method based on the time-varying effect of current density according to claim 1 is characterized in that: In step S101, The chloride ion diffusion coefficient model of the grouting anchor cable changing with temperature is: ； in, is the chloride ion diffusion coefficient on the surface of the grouting anchor cable; is the surface temperature of the grouting anchor cable at room temperature; is the surface temperature of the grouting anchor cable in the service state; is the effective diffusion coefficient of chloride ions in the underground surrounding rock in contact with the grouting anchor cable at room temperature; is the activation constant value.

3. The anchor cable corrosion strength degradation detection method based on the time-varying effect of current density according to claim 1 is characterized in that: In step S104, according to the formula: ； Determine the real-time corrosion rate of the grouting anchor cable ; in, is the relative atomic mass of the material of the grouting anchor cable; The grouting anchor cable Changing corrosion current density; is the number of electron losses of the material of the grouting anchor cable; is the density of the material of the grouting anchor cable.

4. The anchor cable corrosion strength degradation detection method based on the time-varying effect of current density according to claim 1 is characterized in that: In step S104, The time-varying model of corrosion strength degradation of the grouting anchor cable is: ； in, is the existing maximum bearing capacity of the grouting anchor cable; is the ultimate tensile strength of the grouting anchor cable; is the equivalent initial radius of the grouting anchor cable; is the relative atomic mass of the material of the grouting anchor cable; The grouting anchor cable Changing corrosion current density; is the number of electron losses of the material of the grouting anchor cable; is the density of the material of the grouting anchor cable.

5. The anchor cable corrosion strength degradation detection method based on the time-varying effect of current density according to claim 1 is characterized in that: In step S105, The existing maximum bearing capacity of the grouting anchor cable The preset support failure threshold A comparison is performed to determine the support failure risk of the grouting anchor cable.

6. The anchor cable corrosion strength degradation detection method based on the time-varying effect of current density according to claim 5 is characterized in that: According to the formula: ； Determine the support failure threshold corresponding to different support failure risks ; in, is the maximum initial bearing capacity of the grouting anchor cable.

7. An anchor cable corrosion strength degradation detection system based on the time-varying effect of current density, characterized in that: include: A chloride ion diffusion model is configured to construct a chloride ion diffusion coefficient model of a grouting anchor cable that varies with temperature based on the acquired tunnel working surface temperature, so as to determine the chloride ion diffusion coefficient on the surface of the grouting anchor cable; The first time-varying model is configured to construct a first current density time-varying model of the grouting anchor cable according to the chloride ion diffusion coefficient on the surface of the grouting anchor cable and the chloride ion concentration on the surface of the grouting anchor cable obtained; wherein the first current density time-varying model is: ； In the formula, The grouting anchor cable is at time The corrosion current density of is the chloride ion concentration on the surface of the grouting anchor cable; is the chloride ion concentration on the surface of the grouting body; is the chloride ion diffusion coefficient on the surface of the grouting anchor cable; is the surface temperature of the grouting anchor cable in the service state; is the resistivity of the underground surrounding rock in contact with the grouting anchor cable; is the existing thickness of the surface grouting body of the grouting anchor cable; The second time-varying model is configured to construct a second current density time-varying model of the grouting anchor cable that varies with time according to the chloride ion diffusion coefficient and the first current density time-varying model; wherein the second current density time-varying model is: ； in, The grouting anchor cable Changing corrosion current density; A corrosion calculation unit is configured to construct a corrosion strength degradation time-varying model of the grouting anchor cable based on the second current density time-varying model and the physical parameters of the grouting anchor cable to determine the existing maximum bearing capacity of the grouting anchor cable; The risk judgment model is configured to determine the support failure risk of the grouting anchor cable based on the existing maximum bearing capacity of the grouting anchor cable and according to a preset support failure threshold.

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