Prestressed anchor rod corrosion test device

Abstract

The invention discloses a pre-stressed anchor rod corrosion test device, which comprises a kettle system comprising a kettle body and a kettle cover; an anchoring base plate is mounted at the bottom of the kettle body; the prestress loading system comprises a counter-force frame installed on the kettle cover, one end of an anchor rod is connected with the anchoring base plate, the other end of the anchor rod extends to the counter-force frame and is fixed to the anchor rod through an anchorage device, and the anchorage device is configured to apply prestress to the anchor rod according to needs; cement mortar wrapping bodies are poured on the portions, close to the anchoring base plate, of the anchor rods to form anchoring sections; the corrosive liquid circulating system comprises a liquid storage tank, a pipeline which is connected with the liquid storage tank and allows corrosive liquid to enter and exit from the high-temperature and high-pressure kettle, and a corrosive liquid spray head which faces the anchor rod in the kettle body and is connected with the pipeline; the gas pressurization system, the gas pressurization pump and the pipeline which is connected with the gas pressurization pump and allows gas to flow in and out of the high-temperature and high-pressure kettle achieve multi-field coupling of stress, temperature, confining pressure, seepage, chemical corrosion and the like, and the device is closer to the actual rock mass environment.

Description

Technical Field

[0001] The invention relates to the technical field of prestressed anchor rod corrosion testing, in particular to a prestressed anchor rod corrosion testing device. Background Art

[0002] Prestressed anchor rods are widely used in engineering fields such as water conservancy, mining, and tunnels, and play a vital role in the safety and stability of the entire rock mass. As we all know, the temperature of the rock layer increases with depth at a gradient of 1.7-3.0℃ / 100 meters, and deep earth science has become an inevitable trend in the development of mining and energy storage engineering. However, the special and complex rock environment in the deep ("three highs and one disturbance", i.e. high temperature, high humidity, high ground stress, and strong disturbance during excavation) usually causes serious erosion to prestressed anchor rods that have been in service for a long time. Furthermore, the safety and stability of rock mass engineering also faces severe challenges, which puts higher requirements on the stability and durability of permanent support structures.

[0003] Previous studies have shown that corrosion is the biggest factor affecting the durability of prestressed anchor rods, which directly determines the service life of the anchor structure. At present, there are few reports on the corrosion test equipment of prestressed anchor rods in special and complex rock environments at home and abroad, and there are mainly the following deficiencies:

[0004] (1) The factors affecting corrosion are relatively simple, especially the conditions of high confining pressure (30 MPa), high temperature (100 °C), dry-wet cycle, etc. cannot be simulated, which is quite different from the actual service conditions of anchor structures in deep rock mass and cannot truly restore the rock mass environment of prestressed anchor rods;

[0005] (2) Most of them are stress corrosion test devices for testing the free section of anchor bolts, and rarely involve corrosion status monitoring of the anchoring section, which makes it impossible to systematically study the aging evolution behavior of prestressed anchor bolts and reasonably evaluate the remaining life;

[0006] (3) The Chinese patent application with publication number CN117405496A discloses an anchor rod and stress corrosion test system and method for simulating a complex geotechnical environment. The confining pressure mode is to apply torque to the nut of the rectangular clamp through a torque wrench to achieve confining pressure test on the anchor body. The disadvantage is that the torque is unevenly applied and the confining pressure is limited, making it difficult to intuitively and accurately record the rust expansion and cracking process of the mortar protective layer in the anchoring section of the prestressed anchor rod;

[0007] Based on the above, a prestressed anchor corrosion test device is urgently needed to solve the problems in the prior art. Summary of the invention

[0008] The purpose of the present invention is to provide a prestressed anchor corrosion test device, which can effectively solve the problems existing in the above-mentioned prior art.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solution: a prestressed anchor corrosion test device, comprising:

[0010] The kettle system comprises a kettle body and a kettle cover, wherein the kettle cover is provided with several types of monitoring modules, each monitoring module being configured to monitor corresponding parameters in the kettle body; an anchoring base plate is provided at the bottom of the kettle body;

[0011] A prestressed loading system, comprising a reaction frame mounted on the kettle cover, wherein one end of an anchor rod is connected to the anchor base plate, and the other end extends to the reaction frame and is fixed to the anchor rod by an anchor, wherein the anchor is configured to apply prestress to the anchor rod as required; and

[0012] The anchor rod is poured with cement mortar inclusions near the anchor base plate to form an anchoring section;

[0013] A corrosive liquid circulation system, comprising a liquid storage tank, a pipeline connected to the liquid storage tank and for supplying the corrosive liquid to and from the high-temperature and high-pressure autoclave, and a corrosive liquid spray head connected to the pipeline in the autoclave body and facing the anchor rod;

[0014] A gas boosting system, a gas boosting pump and a pipeline connected to the gas boosting pump and for supplying gas to and from the high-temperature and high-pressure autoclave.

[0015] Preferably, the several types of monitoring modules include a thermometer, a safety valve and a pressure gauge, and the outer wall of the kettle body is provided with a temperature control device, and the temperature control device is configured to adjust the temperature inside the kettle body to 0-100°C.

[0016] Preferably, the kettle cover includes an insulation cover and a sealing cover, and the insulation cover and the sealing cover are preset with multiple circular holes, the circular holes are used for anchor rods or monitoring modules to pass through, and each of the circular holes is provided with a sealing ring, a foam insulation layer is pasted on the bottom of the insulation cover, and the sealing cover covers the outside of the insulation cover.

[0017] Preferably, the reaction frame comprises a rectangular panel and a plurality of cylindrical support rods, wherein the cylindrical support rods are installed between the rectangular panel and the kettle cover, and the cylindrical support rods support the rectangular panel to be parallel to the kettle cover.

[0018] Preferably, the corrosive liquid circulation system further includes, in order according to the direction of flow of the corrosive liquid:

[0019] The direction from the liquid storage tank to the corrosion liquid nozzle is connected in sequence through pipelines: a first liquid outlet control valve, a rotor flow meter and a high-pressure water pump a;

[0020] The direction of the return flow to the liquid storage tank is connected in sequence through pipelines: the filter mechanism, the second liquid outlet control valve, the second liquid inlet control valve, the rotor flowmeter b, the high-pressure water pump b and the third liquid inlet control valve enter the liquid storage tank; and

[0021] The second liquid inlet control valve is provided with a branch circuit, and the branch circuit is connected to the liquid extraction control valve and the liquid extraction container in sequence through a branch pipe.

[0022] The filtering mechanism comprises an inner tube coaxially arranged in the pipeline, the top opening of the inner tube is trumpet-shaped, and the top of the trumpet-shaped opening is in contact with the inner wall of the pipeline; a filter plate is slidably installed in the inner tube along the axial direction, and the filter plate is initially located near the top of the inner tube; and

[0023] The inner tube is provided with filtering holes at least partially upward from the bottom opening.

[0024] Preferably, the corrosive liquid circulation system also includes a circulation rack, which is arranged between the corrosive liquid nozzle and the anchor rod, and the circulation rack is wrapped around the outside of the anchor rod, and the circulation rack includes a plurality of circulation disks arranged along the axial direction of the anchor rod, each of the circulation disks is provided with an annular groove, and the annular groove is arranged to be inclined downward from one end of the corrosive liquid nozzle toward the opposite end, and an overflow weir is arranged on the side of the anchor rod, and the overflow weirs of each part of the annular groove are flush in the horizontal direction, and the annular groove is configured to guide the corrosive liquid to flow along the axial direction of the anchor rod and overflow from the overflow weir toward the anchor rod at the same time.

[0025] Preferably, the corrosive liquid circulation system is opened and closed at a preset time.

[0026] Preferably, a plurality of resistive strain gauges and at least one acoustic emission probe are spaced apart in the portion of the anchor rod above the anchoring section.

[0027] Preferably, the kettle system is also provided with an electrochemical corrosion testing system, which includes a reference electrode and an auxiliary electrode resistant to high temperature and high pressure, and the reference electrode and the auxiliary electrode are connected to an electrochemical workstation outside the kettle body through leads to monitor the anchor corrosion current density in real time.

[0028] Beneficial effects: The present invention cooperates with the kettle system with the prestressed loading system, the corrosive liquid circulation system, the gas pressurization system and the electrochemical corrosion testing system to simulate various test conditions such as high temperature, high pressure, dry-wet cycle, chemical corrosion, etc. in the kettle body, thereby realizing multi-field coupling such as stress-temperature-confining pressure-seepage-chemical corrosion, which is closer to the actual rock environment; the confining pressure loading is uniform, and the rust expansion and cracking of the protective layer are accurately monitored; the post-corrosion solution can be extracted at any time for chemical analysis, the operation method is simple, economical and stable, the test results are more accurate and scientific, and it has a high value for promotion and application. Among them, through the setting of the circulation frame, the corrosive liquid can be evenly and simultaneously drained to the anchor rod, so that the factors can be controlled and the accuracy of the experiment is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0030] In the attached picture:

[0031] Figure 1 A schematic diagram of the main structure of a prestressed anchor corrosion test device that can simulate a special complex rock environment provided by an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of a reaction frame structure of a prestressed anchor corrosion test device that can simulate a special complex rock mass environment provided by an embodiment of the present invention;

[0033] Figure 3 It is a structural schematic diagram of the filtering mechanism of the present invention;

[0034] Figure 4 It is a structural schematic diagram of the circulation frame of the present invention;

[0035] Figure 5 The graph of strain variation over time monitored by strain gauges on the surface of prestressed anchor rods;

[0036] Figure 6 Corrosion current density versus time graph monitored by the electrochemical corrosion test system;

[0037] Figure 7 Polarization curves monitored by electrochemical corrosion testing systems;

[0038] Figure 8 Electrochemical impedance spectroscopy for monitoring electrochemical corrosion testing systems;

[0039] Fig. 9 This is the acoustic emission signal diagram of the early stage of corrosion of prestressed anchor rods;

[0040] Numbers in the figure:

[0041] A. Kettle system;

[0042] A1, kettle body; A2, insulation cover; A3, sealing cover; A4, temperature control device; A5, thermometer; A6, pressure gauge; A7, safety valve a;

[0043] B. Prestressed loading system;

[0044] B1, free section; B2, anchoring section; B3, anchor pad; B4, pressure sensor; B5, anchor; B6, reaction frame; B6-1, rectangular panel; B6-2, support rod; B6-3, nut; B6-4, anchor rod reserved hole; B6-5, support rod reserved hole; B7, anchor base plate;

[0045] C. Corrosive liquid circulation system;

[0046] C1, liquid storage tank; C2, liquid discharge control valve; C3, rotor flowmeter a; C4, high-pressure water pump a; C5; liquid inlet control valve; C6, nozzle; C7, filter mechanism; C7-1, inner tube; C7-2, trumpet-shaped opening; C7-3, filter plate; C7-4, filter hole; C7-5, slide; C7-6, slider; C8, liquid discharge control valve; C9, liquid collection control valve; C10, liquid inlet control valve; C11, rotor flowmeter b; C12, high-pressure water pump b; C13, liquid inlet control valve; C14, pressure gauge; C15, safety valve b; C16, liquid collection container; C17, circulation rack; C17-1, circulation disk; C17-2, ring groove; C17-3, overflow weir; C17-4, notch;

[0047] D. Gas booster system;

[0048] D1, air outlet control valve; D2, gas booster pump; D3, air inlet control valve; D4, pipeline hole;

[0049] E. Electrochemical corrosion test system;

[0050] F. Acoustic emission device;

[0051] G. Strain gauge;

[0052] H. Infrared device; DETAILED DESCRIPTION

[0053] The embodiments of the present invention are described below in conjunction with the accompanying drawings in the embodiments of the present invention. The terms used in the implementation mode of the present invention are only used to explain the specific embodiments of the present invention, and are not intended to limit the present invention.

[0054] Example: Figure 1-Figure 2 As shown, a prestressed anchor corrosion test device includes: a kettle system A, a prestressed loading system B, a corrosion liquid circulation system C, a gas booster system D, an electrochemical corrosion test system E, an acoustic emission device F, a strain gauge G, and an infrared device H.

[0055] The kettle system A consists of a cylindrical kettle body A1 made of thick-walled stainless steel and a circular kettle cover. The outer wall of the kettle body A1 is provided with a temperature control device A4, whose temperature control range is 0-100℃, which can control the temperature inside the kettle body A1 to remain constant, with an error range of ±0.1℃; an anchor base plate B7 with threaded holes is provided at the bottom of the kettle body A1 and is sealed and welded to the bottom plate; the kettle cover is divided into an insulation cover A2 and a sealing cover A3, wherein a foam insulation layer is pasted on the bottom of the insulation cover A2, a circular hole is provided in the center of the kettle cover for the anchor rod to pass through, a sealing ring is provided in the circular hole, and a rubber sealing ring is embedded around the kettle cover; several types of monitoring modules are provided on the upper part of the sealing cover A3, including a thermometer A5, a pressure gauge A6 and a safety valve A7, the pressure gauge A6 is used to monitor the air pressure inside the kettle, and the safety valve A7 is used to monitor the air pressure inside the kettle. A7 is used to exhaust when the air pressure in the kettle is too high; a circular hole is provided in the center of the sealing cover A3 for the free section B1 of the anchor rod to pass through, a sealing ring is provided in the circular hole, a rubber sealing ring is embedded around the cover, and a handle for opening the cover is provided on the top of the cover; the kettle system A can provide a constant high-temperature, high-pressure enclosed space, fully considering the high-temperature, high-confining-pressure environment of the anchor rod in the deep rock mass.

[0056] The sealing cover A3 is provided with four threaded round holes for the lower bolts of the reaction frame support rod B6-2 to be twisted and fixed; the sealing cover A3 is also provided with reserved channels for the corrosion liquid pipeline, gas pipeline and the wires required for the strain gauge G, electrochemical corrosion test system E, acoustic emission device F and infrared device H.

[0057] The prestressed loading system B consists of a reaction frame B6, an anchor B5, an anchor rod (anchoring section B2, a free section B1, i.e., the part located above the anchoring section B2), an anchor pad B3, and an anchor base plate B7. Before applying prestress, the reaction frame B6 is assembled first, and four struts B6-2 with threads at both ends are twisted and fastened to the rectangular panel B6-1, wherein a circular hole for the anchor rod to pass through is provided in the center of the rectangular panel B6-1. Threads are threaded at the upper and lower ends of the anchor rod, and the lower end is inserted into the threaded hole of the anchor base plate B7 and twisted and fastened, and the upper end passes through the anchor B5, the pressure sensor B4, and the anchor pad B3 from top to bottom in sequence. A grouting mold is used to cast a cement mortar inclusion at the lower part of the anchor rod to form the anchoring section B2, and water is sprinkled and cured for 28 days to achieve sufficient compressive strength. A torque wrench is used to twist the anchor B5 (e.g., a nut) to apply prestress, and the applied prestress is measured by the pressure sensor B4. The operation is simple and practical.

[0058] In the technical solution provided by the embodiment of the present invention, the corrosive liquid in the liquid storage tank C1 in the corrosive liquid circulation system C enters the high-temperature and high-pressure autoclave body A1 through the first liquid outlet control valve C2, the rotor flowmeter a C3, the high-pressure water pump a C4, and the first liquid inlet control valve C5, and the corrosive liquid sprays and corrodes the anchor rod through the nozzle C6; the sprayed corrosive liquid enters the liquid storage tank C1 through the filtering mechanism C7, the second liquid outlet control valve C8, the second liquid inlet control valve C10, the rotor flowmeter b C11, the high-pressure water pump b C12, and the third liquid inlet control valve C13 to complete the corrosion cycle; according to the test needs, the liquid collection control valve C9 can be opened at any time to put the corrosive liquid into the liquid collection container C16 to realize the chemical analysis of the corrosive liquid; the rated working pressure of the high-pressure water pump a C4 is 50MPa, which can fully meet the experimental needs; the pressure gauge C14 and the safety valve b C15 are also installed on the liquid storage tank C1.

[0059] Based on the above, further reference Figure 3 As shown, the filtering mechanism C7 includes an inner tube C7-1 coaxially arranged in the pipeline, the top opening of the inner tube C7-1 is trumpet-shaped, and the top of the trumpet-shaped opening C7-2 is in contact with the inner wall of the pipeline; it is used to receive the reflux corrosive liquid flowing down from the pipeline, and a filter plate C7-3 is slidably installed in the inner tube C7-1 along the axial direction, and the filter plate C7-3 is initially located near the top of the inner tube C7-1; and the inner tube C7-1 is provided with a filtering hole C7-4 starting from the bottom opening and at least partially upward, refer to Figure 3 As shown, a slide groove C7-5 can be opened inside the inner tube, and the side of the filter plate C7-3 is slidably connected to the slide groove through a slider C7-6, and an elastic structure, such as a spring, is provided on the slider. The slider C7-6 area is controlled to move upward by the spring. In the initial state, the spring drives the slider C7-6 and the filter plate C7-3 to be at the highest end. At this time, the reflux corrosive liquid enters the filter plate C7-3 in the inner tube and is filtered through the filter plate C7-3. After filtering for a certain period of time, a certain amount of impurities accumulate on the filter plate C7-3, and the filter plate C7-3 slides down due to gravity. At this time, the filter hole C7-4 on the inner tube is exposed, and the reflux corrosive liquid is filtered through the filter hole C7-4. As the impurities continue to accumulate and pile up, the filter plate C7-3 ensures the circulation of the filtration by gradually descending, thereby increasing the filtration time and ensuring the normal operation of the entire experimental device.

[0060] Based on the above content, further, the corrosive liquid circulation system also includes a circulation rack C17, which is arranged between the corrosive liquid nozzle C6 and the anchor rod, and the circulation rack C17 is wrapped around the outside of the anchor rod, and the circulation rack C17 includes a plurality of circulation disks C17-1 arranged along the axial direction of the anchor rod, and each circulation disk C17- is provided with an annular groove C17-2, and the annular groove C17-2 is arranged to be inclined downward from one end of the corrosive liquid nozzle toward the opposite end, and an overflow weir C17-3 is arranged on one side of the anchor rod of the annular groove C17-2, and the overflow weirs C17-3 of each part of the annular groove C17-2 are flush in the horizontal direction, and the annular groove C17-2 is configured to guide the corrosive liquid to flow along the axial direction of the anchor rod, and overflow from the overflow weir C17-3 toward the anchor rod at the same time;

[0061] Among them, reference Figure 4 As shown, a notch C17-4 is provided on the side of each circulation disk C17-1 facing the corrosion liquid nozzle. When the corrosion liquid nozzle is working, the corrosion liquid enters into the circulation disk C17-1 of each layer from the notch C17-4. In the initial state, under the action of the inclined annular groove, the corrosion liquid flows along the annular groove C17-2 toward the side away from the corrosion liquid nozzle, and is affected by the overflow weir C17-3 and the state of the annular groove C17-2 until the corrosion liquid is higher than the overflow weir C17-3 and begins to overflow toward the anchor rod, so that all circumferential parts of the anchor rod are in contact with the corrosion liquid at the same time, and the setting of several circulation disks C17-1 can make up for the loss caused by the axial flow absorption of the corrosion liquid on the anchor rod, thereby ensuring that the entire anchor rod can contact the corrosion liquid under the same conditions to the greatest extent, realizing controllable factors and improving the experimental accuracy.

[0062] The gas boosting system D includes an outlet control valve D1, a gas boosting pump D2, an inlet control valve D3 and a pipeline for supplying gas in and out of the high-temperature and high-pressure autoclave; pipeline holes D4 are evenly arranged on the pipeline wall in the high-temperature and high-pressure autoclave to achieve pressurization in the autoclave and at the same time take into account the evaporation of the corrosive liquid on the surface of the anchor rod.

[0063] The electrochemical corrosion test system E adopts a classic three-electrode system to monitor the corrosion current density of prestressed anchor rods in real time. It can draw polarization curves and electrochemical impedance spectra to further analyze the electrochemical corrosion kinetics of anchor rods.

[0064] In the technical solution provided by the embodiment of the present invention, according to the experimental needs, the temperature control device A4 is started, and the reading of the thermometer A5 is observed to ensure that the temperature is maintained at 100°C; the kettle system A and the corrosive liquid circulation system C are checked for tightness, the safety valve aA7, the safety valve b C15 and the liquid extraction control valve C9 are closed, and air is injected into the high-temperature and high-pressure kettle through the gas booster pump D2 to pressurize the pressure to the test requirement of 30MPa, and the pressure gauge A6 and the pressure gauge C14 are observed. If the reading remains unchanged for a period of time, it is considered that the tightness is good. After ensuring that the high-temperature and high-pressure kettle is well-sealed, the high-pressure water pump a C4 is started to spray the corrosive liquid on the surface of the anchor rod, and the rotor flowmeter reading is observed to determine whether to start the high-pressure water pump b C12 to realize the recycling of the corrosive liquid. In order to more scientifically explore the influence of dry-wet cycles on the corrosion of prestressed anchor rods, the cycle period is set as: spraying for one week, and drying for one week in the high-temperature and high-pressure environment in the kettle.

[0065] Resistive strain gauges are pasted at multiple locations on the free section B1 of the prestressed anchor rod to monitor the development law of local corrosion; acoustic emission probes are pasted on the surface of the free section B1 of the prestressed anchor rod, and the dislocation-slip-microcrack formation-crack propagation-fracture process of the anchor rod metal material is monitored by the acoustic emission device; and the propagation evolution of rust expansion cracks in the mortar protective layer is monitored based on infrared imaging technology; the temperature and confining pressure can be controlled as needed, and the spray flow rate of the corrosive liquid can be adjusted to simulate the dry-wet cycle, and the development law of local corrosion on the anchor rod surface can be monitored based on the strain gauge, and the crack propagation evolution process is explored by using acoustic emission and infrared imaging technologies, and then the remaining life of the prestressed anchor rod is predicted by the state of the prestressed anchor rod; the corrosive liquid can be reused to reduce pollution to the environment; and it provides a valuable reference for conducting indoor accelerated corrosion tests on prestressed anchor rods.

[0066] Based on the above, the anchor rod was tested and the data generated are as follows:

[0067] refer to Figure 5 The figure shows the strain variation over time monitored by the strain gauge on the surface of the prestressed anchor rod. It can be seen that the local deformation of the prestressed anchor rod is first strengthened by tension, and then the tensile strain decreases and turns into compressive strain. The tensile strain increases in the early stage, and then decreases rapidly, and the stress state changes to compression, and then the development gradually slows down.

[0068] refer to Figure 6 As shown, it is a graph showing the change of corrosion current density over time monitored by the electrochemical corrosion test system; Figure 6 It is shown that the corrosion evolution of prestressed anchor rods in this environment basically goes through three stages: a. Steady-state slow corrosion stage; b. Accelerated corrosion stage; c. Steady-state rapid corrosion stage. The entire curve is roughly flat "S" shape. Through fitting, it is known that the corrosion current density curve obeys the Boltzmann equation, and its relationship is:

[0069]

[0070] Where I 1 ,I 2 are the initial and final current densities, I corr is the corrosion current density, in A / cm 2 .

[0071] It can be seen that the corrosion rate of the prestressed anchor rod is very slow at the initial stage of immersion, basically maintaining a certain equilibrium state. As the immersion time increases (about 80 days), the corrosion of the prestressed anchor rod accelerates. When the prestressed anchor rod corrodes to a certain extent, the rust covering the surface hinders the transmission of the corrosive medium, and the anodic dissolution rate per unit time slows down, that is, the corrosion rate changes slowly.

[0072] refer to Figure 7 As shown, it is the polarization curve monitored by the electrochemical corrosion test system; Figure 7 It can be seen that in the entire corrosion cycle, no passivation zone appears in the curve, which means that the prestressed anchor is always in an activated state, the anode is continuously dissolved, and no passivation film is formed; Figure 7 It can be seen from the figure that the corrosion potential of specimen 1 shifts positively with time. During the corrosion period of 100d to 180d, the positive shift of the corrosion potential decreases significantly. This may be related to the fact that the prestressed anchor rods in an oxygen-permeable environment are more likely to form an oxide film during the corrosion period, thereby enhancing the corrosion resistance. As the corrosion potential shifts positively, the oxide film is partially broken down, and the Fe on the electrode is re-converted to Fe 2+ Dissolution occurs in the form of small holes or cracks, which causes the electrode potential to shift negatively. At this time, since the corroded metal part exists in the form of small holes or cracks, the corrosion rate at the pitting area continues to increase.

[0073] refer to Figure 8 As shown, it is the electrochemical impedance spectrum monitored by the electrochemical corrosion test system; Figure 8 The figure shows that the impedance spectrum of the prestressed anchor rod is a capacitive reactance arc with a large radius in the early stage of immersion (within 7 days). The radius of the arc increases slightly after 30 days of immersion. No corrosion occurs on the surface of the specimen, and the surface passivation film is in an unstable state. As the immersion time increases, the chloride ion concentration on the anchor rod surface reaches the depassivation threshold, and the specimen begins to corrode. However, the impedance value is still large, and the corrosion of the anchor rod is not obvious, which is mainly controlled by charge transfer.

[0074] refer to Fig. 9 The figure shows the acoustic emission signal diagram of the initial corrosion of the prestressed anchor rod. It can be seen that within the initial one and a half hours of corrosion, the signal energy is relatively large, indicating that the oxide film on the surface of the specimen has been basically completely corroded within the initial one and a half hours, generating a large number of acoustic emission signals with large amplitudes. The corrosion degree of the prestressed anchor rod specimen detected by the infrared imager is shown in the following table:

[0075]

[0076] It can be seen from the table that the temperature difference of the specimen initially decreases with the increase of the corrosion rate, and an inflection point appears when the corrosion rate approaches 38%.

[0077] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. For ordinary technicians in this technical field, after knowing the contents recorded in the present invention, they can make several equivalent changes and substitutions without departing from the principle of the present invention. These equivalent changes and substitutions should also be regarded as belonging to the protection scope of the present invention.

Claims

1. A prestressed anchor corrosion test device, characterized in that: include: The kettle system comprises a kettle body and a kettle cover, wherein the kettle cover is provided with several types of monitoring modules, each monitoring module being configured to monitor corresponding parameters in the kettle body; an anchoring base plate is provided at the bottom of the kettle body; A prestressed loading system, comprising a reaction frame mounted on the kettle cover, wherein one end of an anchor rod is connected to the anchor base plate, and the other end extends to the reaction frame and is fixed to the anchor rod by an anchor, wherein the anchor is configured to apply prestress to the anchor rod as required; and The anchor rod is poured with cement mortar inclusions near the anchor base plate to form an anchoring section; A corrosive liquid circulation system, comprising a liquid storage tank, a pipeline connected to the liquid storage tank and for supplying the corrosive liquid to and from the high-temperature and high-pressure autoclave, and a corrosive liquid spray head connected to the pipeline in the autoclave body and facing the anchor rod; A gas boosting system, a gas boosting pump and a pipeline connected to the gas boosting pump and for supplying gas to and from the high-temperature and high-pressure autoclave.

2. A prestressed anchor corrosion test device according to claim 1, characterized in that: Several types of monitoring modules include thermometers, safety valves and pressure gauges. The outer wall of the kettle is provided with a temperature control device, which is configured to adjust the temperature inside the kettle to 0-100°C.

3. A prestressed anchor corrosion test device according to claim 1 or 2, characterized in that: The kettle cover includes an insulation cover and a sealing cover, and the insulation cover and the sealing cover are preset with multiple circular holes, the circular holes are used for anchor rods or monitoring modules to pass through, and each of the circular holes is provided with a sealing ring, a foam insulation layer is pasted on the bottom of the insulation cover, and the sealing cover covers the outside of the insulation cover.

4. A prestressed anchor corrosion test device according to claim 1, characterized in that: The reaction frame comprises a rectangular panel and a plurality of cylindrical support rods, wherein the cylindrical support rods are installed between the rectangular panel and the kettle cover, and the cylindrical support rods support the rectangular panel to be parallel to the kettle cover.

5. The prestressed anchor corrosion test device according to claim 1, characterized in that: The corrosive liquid circulation system further includes the following in order according to the direction of the corrosive liquid flow: The direction from the liquid storage tank to the corrosion liquid nozzle is connected in sequence through pipelines: a first liquid outlet control valve, a rotor flow meter and a high-pressure water pump a; The direction of the return flow to the liquid storage tank is connected in sequence through pipelines: the filter mechanism, the second liquid outlet control valve, the second liquid inlet control valve, the rotor flowmeter b, the high-pressure water pump b and the third liquid inlet control valve enter the liquid storage tank; and The second liquid inlet control valve is provided with a branch circuit, and the branch circuit is connected to the liquid extraction control valve and the liquid extraction container in sequence through a branch pipe.

6. A prestressed anchor corrosion test device according to claim 5, characterized in that: The filtering mechanism comprises an inner tube coaxially arranged in the pipeline, the top opening of the inner tube is trumpet-shaped, and the top of the trumpet-shaped opening is in contact with the inner wall of the pipeline; a filter plate is slidably installed in the inner tube along the axial direction, and the filter plate is initially located near the top of the inner tube; and The inner tube is provided with filtering holes at least partially upward from the bottom opening.

7. A prestressed anchor corrosion test device according to claim 1 or 5, characterized in that: The corrosive liquid circulation system also includes a circulation rack, which is arranged between the corrosive liquid nozzle and the anchor rod, and the circulation rack is wrapped around the outside of the anchor rod. The circulation rack includes a plurality of circulation disks arranged along the axial direction of the anchor rod, and each of the circulation disks is provided with an annular groove, and the annular groove is arranged to be inclined downward from one end of the corrosive liquid nozzle toward the opposite end, and an overflow weir is arranged on the side of the anchor rod. The overflow weirs of each part of the annular groove are flush in the horizontal direction, and the annular groove is configured to guide the corrosive liquid to flow along the axial direction of the anchor rod and overflow from the overflow weir toward the anchor rod at the same time.

8. A prestressed anchor corrosion test device according to claim 7, characterized in that: The corrosive liquid circulation system is opened and closed according to a preset timing.

9. A prestressed anchor corrosion test device according to claim 1, characterized in that: The portion of the anchor rod located above the anchoring section is provided with a plurality of resistance strain gauges and at least one acoustic emission probe at intervals.

10. A prestressed anchor corrosion test device according to claim 1, characterized in that: The kettle system is also provided with an electrochemical corrosion test system, which includes a reference electrode and an auxiliary electrode resistant to high temperature and high pressure. The reference electrode and the auxiliary electrode are connected to an electrochemical workstation outside the kettle through leads to monitor the anchor corrosion current density in real time.

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