Tunnel anchor cable based on hot melt structure

Abstract

The application relates to a tunnel anchor cable based on a hot-melt structure, which at least comprises a monitoring part for monitoring anchoring force of the anchor cable, the monitoring part is installed on an anchor cable bundle, which at least comprises a strain sensor for monitoring and transmitting stress change data of the anchor cable bundle; a sampling period of the strain sensor is set according to a preset strain amplitude corresponding to stress change of the anchor cable bundle; in the process of recovering the anchor cable bundle, time-related stress change information of the anchor cable bundle is recorded and transmitted through the strain sensor with the preset strain amplitude of the anchor cable bundle as a starting event.

Description

[0001] Case Analysis

[0002] The original basis for this divisional application is Chinese patent application with application number CN 202210362034X, application date April 7, 2022, entitled "An anchor cable recycling device and method based on a thermoplastic structure". Technical Field

[0003] This invention relates to the field of geotechnical engineering technology, to drilling technology for soil or rock, and particularly to a tunnel anchor cable based on a thermoplastic structure. Background Technology

[0004] Currently, anchoring engineering is widely used in various fields such as foundation pits, tunnels, and disaster management. After the expected goal is achieved, some components in the anchoring project, such as the anchor cables and anchor rods in the free section, become useless. These components can be recycled, so removing them can not only reduce material consumption but also lower construction costs and save resources.

[0005] To address this issue, recyclable anchor cable technology has been developed. After the anchor cable has completed its function, it can be recycled, preventing it from exceeding the building's set-line and reducing construction costs. Currently, several recyclable anchor cable technologies have been developed. Recyclable anchor cables are safe, fast, and easy to recover; the recycled steel strands can be reused, overcoming the shortcomings of earlier anchor cable technologies.

[0006] Thermofused recyclable anchor cable is a commonly used type of recyclable anchor cable technology. Its principle is mainly to disassemble the core of the thermofused anchor by energizing it. After the core disassembly is completed after the energization reaches a certain time, the steel strand is pulled out and recycled.

[0007] An article titled "Application and Research of a Novel Thermofused Detachable Core Anchor Cable" published in the journal *Engineering Survey* describes a thermofused anchor. This anchor's thermofusion device mainly consists of a metal anchor ring and metal clips for the anchor hole. The metal anchor ring, with its outer wall encased in an electric heating ring and connected external conductors, is the dominant part of the thermofusion device. The metal clips are frustum-shaped with a threaded through-hole for embedding the anchor cable. When the anchor cable is inserted into the metal clip, the threads on the inner surface of the through-hole interfere with the frustum-shaped through-hole, increasing the ultimate pull-out resistance and stabilizing the anchor cable. The inner wall of the anchor hole is filled with a bushing made of thermofused material, tightly fitted to the metal clips. After the anchor cable is used in the anchoring project, electricity is supplied to the conductor through a ground device. The electric heating ring generates heat, heating the metal anchor ring and melting the bushing, thereby releasing the anchor cable bundle and allowing the free section of the anchor cable bundle to be removed.

[0008] However, these thermofused anchors require energization to bring the thermofused ring to a certain temperature before they can melt the anchor cable bundle and be recovered, resulting in low recovery efficiency. Secondly, the design structure of these thermofused anchors typically only considers the recovery of the free section of the anchor cable. During the recovery process, as the anchor cable bundle moves, it is very likely to affect the anchoring force of the original anchor. These thermofused anchors do not have monitoring components to monitor the stress / strain of the free section of the anchor cable, thus they cannot effectively monitor the real-time changes in the anchoring force during the recovery process. Consequently, they cannot maintain or increase the anchoring force of the anchor when it weakens, resulting in poor application performance of these thermofused anchors.

[0009] Even though existing technologies possess devices or mechanisms capable of monitoring changes in anchor cable stress, their monitoring and transmission frequencies are typically known and fixed. However, for anchorages, when the anchoring force of the anchorage experiences abnormal attenuation, the anchoring effect of the anchor cable will be significantly reduced or even disappear. Monitoring devices usually only send corresponding monitoring data at preset sampling nodes, meaning that control equipment can only determine the anchoring force of the anchor cable upon receiving the corresponding monitoring data. Therefore, when abnormal changes occur in the anchoring force, conventional monitoring and judgment methods have a certain lag. This lag may cause construction personnel to miss the optimal time for grouting, thus failing to restore the anchoring force to its original level in a timely manner.

[0010] Furthermore, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making this invention, but due to space limitations, not all details and contents were listed in detail. However, this does not mean that the present invention does not possess the features of these prior art. On the contrary, the present invention already possesses all the features of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0011] In view of the shortcomings of the prior art, the present invention provides a tunnel anchor cable based on a thermoplastic structure, which aims to solve at least one or more technical problems existing in the prior art.

[0012] To achieve the above objectives, the present invention provides a tunnel anchor cable based on a thermoplastic structure, comprising:

[0013] The hot-melting part has a housing that snaps into the anchor cable bundle, the housing encapsulating a hot-melting agent, which includes an activating component and a melting component;

[0014] The heating element is connected to the housing and comes into physical contact with the activating component;

[0015] A controller is used to control the heating components to physically heat the activating components;

[0016] in,

[0017] When the heating component is controlled by the controller to physically heat the activating component, the activating component can release a first chemical reaction heat based on the physical heating and ignite the melting component through the first chemical reaction heat. The melting component burns due to the first chemical reaction heat and releases a second chemical reaction heat. When the melting component comes into contact with the anchor cable bundle, the melting component can melt the anchor cable bundle through the second chemical reaction heat.

[0018] In this invention, the melting of the anchor cable bundle is mainly accomplished by the high amount of chemical heat generated by the hot-melt reagent. Compared to continuously heating the anchor cable bundle with an energized wire to melt it, the hot-melt reagent can release a large amount of heat instantly through an oxidation-reduction reaction. Therefore, the anchor cable bundle can be melted and recovered in a very short time. Unlike existing technologies that require a lot of time to melt the anchor cable bundle when continuously heating it with an energized wire, resulting in extremely low anchor cable recovery efficiency, and because the operation of the energized wire in deep underground space is also relatively complex, it is not possible to effectively guarantee that the energized wire can continuously and stably heat the anchor cable bundle. In this invention, the energized wire only needs to provide an initial heat energy sufficient to ignite the hot-melt reagent. The subsequent melting of the anchor cable is achieved by the molten hot-melt reagent, which can provide a high amount of heat instantly. Therefore, it does not require too much energy from the energized wire. The entire melting process takes very short time, and the efficiency and stability of anchor cable recovery are significantly improved.

[0019] Preferably, the heating assembly includes a signal line and a heating wire, the signal line being electrically connected to the heating wire and the controller, wherein at least a portion of the heating wire is in physical contact with the activating component so as to ignite the activating component under the drive of the controller, thereby giving it thermal energy for igniting the melting component.

[0020] Preferably, the hot melt agent encapsulated in the shell includes a magnesium strip, an igniter, and an aluminothermic agent, with the magnesium strip in direct contact with the heating wire. When the heating wire is controlled to operate by the controller, the heating wire transfers heat to the magnesium strip to ignite it. The burning of the magnesium strip ignites the igniter and the aluminothermic agent, causing the aluminothermic agent to transform into a molten state through an aluminothermic reaction.

[0021] Preferably, a sealing plate for encapsulating the hot melt agent is provided on one side of the shell clamped to the anchor cable bundle. When the thermite comes into contact with the igniter and turns into a molten state, the thermite melts the sealing plate and flows out through the shell to contact the anchor cable bundle and melt it.

[0022] Preferably, the hot-melt reagent is filled into the housing through a reagent channel, and the reagent channel is sealed by a shape-matched plug, wherein the heating wire passes through the plug and is inserted into the housing and in physical contact with the magnesium strip.

[0023] Preferably, the anchor cable bundle is equipped with a monitoring unit, which includes at least a strain sensor. The strain sensor is communicatively connected to the controller in a manner that monitors and transmits stress change data of the anchor cable bundle.

[0024] Preferably, the anchor cable bundle is equipped with a grouting section, which consists of a grouting device and a grouting channel. The grouting channel includes several grouting pipes disposed within the anchor cable bundle, and the grouting pipes are connected to the grouting device located outside the borehole.

[0025] Preferably, when the controller determines that the anchoring force of the anchor cable bundle is lower than a set threshold based on the stress monitoring data of the strain sensor, secondary grouting is performed on the anchoring section of the anchor cable bundle through the grouting section.

[0026] Preferably, the present invention relates to a method for recycling tunnel anchor cables based on a thermoplastic structure, the recycling method comprising:

[0027] Fill and encapsulate the hot-melt reagent inside the shell;

[0028] Install the heating assembly into the housing and bring it into physical contact with the hot melt reagent;

[0029] The housing is snapped into the anchor cable bundle, and the heating components are controlled by a controller.

[0030] The heating components are controlled to physically heat the hot-melt reagent, so that the hot-melt reagent releases the heat of chemical reaction.

[0031] The hot-melting agent is brought into contact with the anchor cable bundle to melt and recover the anchor cable bundle by means of the heat of chemical reaction.

[0032] Preferably, the recycling method further includes:

[0033] Install the monitoring unit and grouting unit to the anchor cable bundle;

[0034] The stress changes of the anchor cable bundle are monitored in real time by the strain sensor in the monitoring unit;

[0035] When the anchoring force of the anchor cable bundle is lower than the set threshold, secondary grouting is performed on the anchor cable through the grouting section.

[0036] The beneficial technical effects of this invention include: the recyclability of anchor cables and anchor rods is achieved through a controllable hot-melt device, which reduces material consumption and engineering costs. In particular, the controllable hot-melt device of this invention has a simple structure, requires no high-precision machining, has low production costs, is easy to use and maintain, and has high recycling efficiency. The monitoring unit monitors the stress-strain changes of the free section of the anchor cable, which can reflect the magnitude of the anchoring force and thus evaluate the expected anchoring effect of the anchor cable. If the anchoring project does not achieve the expected results, secondary grouting can be performed using the grouting unit to enhance the anchoring force of the anchor cable. The main components of the anchor cable adopt a modular and mechanized design, which facilitates processing and manufacturing, reduces production costs, and the modular design makes disassembly and assembly simple, and maintenance and replacement are faster. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a tunnel anchor cable based on a thermoplastic structure, according to a preferred embodiment of the present invention.

[0038] Figure 2 This is a schematic diagram of the structure of the hot-melt section according to a preferred embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of the hot-melt section according to another preferred embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the shell structure of the hot-melt section according to a preferred embodiment of the present invention.

[0041] List of reference numerals

[0042] 1: Anchor cable bundle; 2: Hot melt section; 3: Anchoring section; 4: Grouting channel; 5: Controller; 6: Grouting device; 7: Drill hole; 8: Strain sensor; 9: Signal line; 10: Signal transmission channel; 11: Heating wire; 12: Magnesium strip; 13: Ignition agent; 14: Thermite; 15: Sealing plate; 16: Shell; 17: Agent channel; 18: Sealing plug; 19: Glycerin bottle; 20: Potassium permanganate. Detailed Implementation

[0043] The following is a detailed explanation with reference to the accompanying drawings.

[0044] This invention provides a tunnel anchor cable based on a thermoplastic structure, comprising a thermoplastic section 2 for anchor cable recovery, a monitoring section for monitoring the anchor cable's anchoring force, and a grouting section for secondary grouting of the anchor cable. Specifically, the thermoplastic section 2, the monitoring section, and the grouting section are mechanically and / or electrically connected to the anchor cable bundle 1 for use in conjunction with the anchor cable.

[0045] according to Figure 1In one preferred embodiment, the monitoring unit may include a controller 5 and a strain sensor 8 (e.g., a strain gauge). The strain sensor 8 is connected to the controller 5 via a signal transmission channel 10 (e.g., a signal transmission cable). Specifically, during the use or retrieval of the anchor cable, the strain sensor 8 can monitor the stress change data of the anchor cable bundle 1 in real time and transmit the stress change data to the controller 5 via the signal transmission channel 10. The controller 5 can analyze and calculate the stress change data of the anchor cable bundle 1, thereby providing data support for the anchor cable anchoring quality. In particular, the signal transmission method of the strain sensor 8 can be not only wired but also wireless, depending on the application scenario of the anchor cable.

[0046] according to Figure 1 In a preferred embodiment shown, the grouting section may consist of a grouter 6 and a grouting channel 4. Further, the grouting channel 4 includes multiple grouting pipes installed within the anchor cable bundle 1, and the grouting channel 4 is connected to the grouter 6 outside the borehole opening 7. Specifically, during the recovery of the anchor cable bundle 1, if the monitoring unit detects and determines that the current anchoring force of the anchor cable bundle 1 is less than a set threshold, secondary grouting can be performed on the anchoring section 3 of the anchor cable bundle 1 through the grouting section composed of the grouter 6 and the grouting channel 4 to enhance the anchoring force of the anchor cable bundle 1, especially the anchoring section 3.

[0047] According to a preferred embodiment, in the prior art, when monitoring stress changes in the anchor cable bundle 1 using a strain sensor 8, the monitoring and transmission frequency of the strain sensor 8 is usually known and fixed. However, when the anchoring force of the anchor cable bundle 1 experiences abnormal attenuation, the anchoring effect of the anchor cable bundle 1 will be greatly reduced or even disappear. The strain sensor 8 typically only sends corresponding monitoring data at preset sampling nodes, and the controller 5 can only determine the anchoring force of the anchor cable bundle 1 upon receiving the corresponding monitoring data. Therefore, when the anchoring force of the anchor cable bundle 1 changes abnormally, conventional monitoring and judgment methods have a certain lag. This lag is problematic for... For anchor cable reinforcement of strata, this is extremely unfavorable, especially when the delayed transmission and reception effect continues to accumulate. The error between the actual change in the anchoring force of the anchor cable bundle and the expected change may be as high as several times. The change in the anchoring force of the anchor cable bundle, especially when retrieving anchor cable bundle 1, also affects the timing of secondary grouting of the anchor cable through the grouting section, thus affecting the anchoring quality. Especially when the anchoring force of anchor cable bundle 1 is significantly lower than a certain range of the set threshold, if secondary grouting is not carried out in time, even if grouting is carried out later, the anchoring force of anchor cable bundle 1 may not be able to be restored to the original level because the best time for grouting is missed.

[0048] According to a preferred embodiment, in this invention, the sampling period of the strain sensor 8 can be set according to a preset strain amplitude corresponding to the stress change of the anchor cable bundle 1. In other words, during the retrieval of the anchor cable bundle 1, the time-related stress change information of the anchor cable bundle 1 is recorded and transmitted via the strain sensor 8 using the preset strain amplitude of the anchor cable bundle 1 as the trigger event. Specifically, the preset strain amplitude can be set by engineering designers based on engineering experience or calculated values ​​based on engineering simulation experiments. For example, for anchoring soil layers with known geological conditions, the attenuation change of the anchor cable bundle 1 when retrieving the anchor cable from the stratum can be simulated by software, and a corresponding time-related change curve of the anchoring force can be generated. Thus, the preset strain amplitude can be set according to the theoretical change trend of the anchoring force of the anchor cable bundle.

[0049] Preferably, the sampling period of the strain sensor 8 is the time consumed for each preset strain amplitude to be generated in the anchor cable bundle 1 or for each preset strain amplitude to be reduced in the anchoring force of the anchor cable bundle 1. When the stress change of the anchor cable bundle 1 accelerates or slows down, the time consumed for the anchor cable bundle 1 to generate a single preset strain amplitude will also change. In particular, the ratio of the sampling period of the strain sensor 8 to the preset strain amplitude can be used to characterize the stress change rate of the anchor cable bundle 1, thereby revealing the anchoring force decay rate of the anchor cable bundle 1. The larger the ratio, the slower the anchoring force decay rate of the anchor cable bundle 1, that is, the longer the time required for the anchor cable bundle 1 to generate a single preset strain amplitude or for its anchoring force to decrease by a single preset strain amplitude. Conversely, the smaller the ratio, the faster the anchoring force decay rate of the anchor cable bundle 1, that is, the shorter the time required for the anchor cable bundle 1 to generate a single preset strain amplitude or for its anchoring force to decrease by a single preset strain amplitude.

[0050] According to a preferred embodiment, when the attenuation rate of the anchoring force of the anchor cable bundle 1 slows down, the strain sensor 8 can reduce the frequency and amount of monitoring data transmitted to the controller 5. This reduces the amount of data interaction and the delay generated during data transmission, making the controller 5's analysis and calculation of the anchoring force more timely and smooth. In particular, it can respond promptly to changes in the anchoring force of the anchor cable bundle 1, thereby enabling timely reinforcement of the anchoring force of the anchor cable bundle 1 through the grouting section.

[0051] According to a preferred embodiment, as the anchoring force of the anchor cable bundle 1 continuously decreases, the risks corresponding to different anchoring force variation ranges are different, and the corresponding grouting volumes are also different. Preferably, for different anchoring force variation ranges, the sampling period of the strain sensor 8 is different, and the corresponding preset strain amplitude is also different. Specifically, engineering designers can set different anchoring force variation ranges for the anchor cable bundle 1 according to the anchoring project requirements, and set different preset strain amplitudes for each anchoring force variation range, so as to adjust the monitoring frequency of the strain sensor 8 on the anchor cable bundle 1 in a timely manner as the anchoring force changes, thereby improving the timeliness of the anchoring force monitoring of the anchor cable bundle 1.

[0052] Specifically, as the anchoring force of the anchor cable bundle continues to decrease, the possibility of anchor cable failure increases. Therefore, as the anchoring force of the anchor cable bundle decreases, the preset strain amplitude of the anchor cable bundle 1 can be linearly / nonlinearly reduced to shorten the corresponding sampling period. This allows the strain sensor 8 to monitor the anchoring force of the anchor cable bundle 1 more frequently, enabling timely detection of changes in the anchoring force. Especially during the continuous decrease in anchoring force, the grouting unit can be activated promptly to perform secondary grouting on the anchor cable, thus addressing the decrease in anchoring force and maintaining the corresponding anchoring effect through timely grouting. Conversely, when the anchoring force of the anchor cable bundle increases or recovers after grouting, the preset strain amplitude of the anchor cable bundle 1 can be linearly / nonlinearly increased with the increase in anchoring force. In this way, even when the anchoring force of the anchor cable bundle continues to decrease... During the process, by shortening the sampling period of the strain sensor 8, the controller 5 can analyze and judge the anchoring force of the anchor cable bundle more frequently and intensively. This allows for timely detection of the attenuation state of the anchoring force and timely initiation of secondary grouting. On the other hand, the monitoring frequency of the strain sensor 8 on the anchoring force of the anchor cable bundle can be adjusted in a timely manner according to the changes in the anchoring force, making the monitoring frequency of the anchoring force of the anchor cable bundle more reasonable and accurate. In particular, for example, when the attenuation of the anchoring force of the anchor cable bundle is weak, frequent monitoring may be unnecessary, as this will increase the amount of data interaction, occupy computing resources and cause delays. At the same time, excessive data output will also generate a certain amount of pseudo data, which will affect the controller 5's analysis and judgment of the anchoring force of the anchor cable bundle, thus affecting the optimal grouting time.

[0053] According to a preferred embodiment, such as Figure 1 As shown, the heat-fused section 2 is secured to the outside of the free section of the anchor cable bundle 1, and it is housed in a shell 16, which serves as the outer casing of the entire device and the carrier of the heat-fused components. Further, as... Figure 4As shown, the shell 16 is a hollow shell made of ceramic, and it is composed of at least two semi-cylindrical shell parts joined together. Each of the two semi-cylindrical shell parts has a partially recessed engaging portion, and the two engaging portions, when combined, form a cylindrical channel for the anchor cable bundle to pass through. Preferably, the shell 16 made of ceramic has good high-temperature resistance, can withstand the ultra-high temperatures generated during the aluminothermic reaction, and the ceramic shell material is inexpensive and the manufacturing process is very simple.

[0054] Specifically, when the anchor cable bundle 1 is recovered using the hot-melt section 2, the various hot-melt components inside the housing 16 are activated by the controller 5 and the signal line 9 connected to the controller 5, ultimately achieving the aluminothermic reaction. Specifically, the ambient temperature generated by the aluminothermic reaction is approximately 2000℃~3000℃. The large amount of heat generated by the aluminothermic reaction can melt the sealing material used for sealing, causing the hot-melt reagent sealed inside the housing 16 to flow out. When the molten hot-melt agent (hot-melt metal) comes into contact with the anchor cable bundle 1, it can melt and break the anchor cable bundle 1, or the extremely high temperature of the molten hot-melt agent can greatly reduce the yield strength of the anchor cable bundle 1, so as to forcefully pull and recover the anchor cable bundle 1.

[0055] According to a preferred embodiment, such as Figure 2 As shown, the housing 16 of the heat-melting section 2 is connected to a heating wire 11, which is connected to a signal line 9. The signal line 9 is externally connected to a controller 5, and the controller 5 can control the operation of the heating wire 11 through the signal line 9. Furthermore, after the controller 5 energizes the signal line 9, the heating wire 11 generates a high temperature. This high temperature can provide energy for the oxidation reaction of the magnesium strip 12 sealed in the housing 16 to ignite the magnesium strip 12. The energy from the combustion of the magnesium strip 12 further ignites the igniter 13. The igniter 13 comes into contact with the thermite 14 in the housing 16 and activates the thermite 14.

[0056] According to a preferred embodiment, after the thermite 14 is activated at high temperature by the igniter 13, a strong oxidation-reduction reaction, namely the thermite reaction, will occur, thereby releasing a large amount of heat and forming a molten metal with a temperature as high as 2000°C. After the molten metal formed by the reaction of the thermite 14 comes into contact with the sealing plate 15 on the side of the shell 16 near the anchor cable bundle 1, the sealing plate 15 will melt, thereby flowing out and coming into contact with the anchor cable bundle 1. The ultra-high temperature of the molten metal can melt the anchor cable bundle 1 or greatly reduce the yield strength of the anchor cable bundle 1. At the same time, with the tensioning equipment outside the borehole 7, the anchor cable bundle 1 can be pulled out, thereby realizing the recovery of the anchor cable bundle 1.

[0057] According to a preferred embodiment, the chemical reagents used in the entire aluminothermic reaction are injected into the interior of the housing 16 through the reagent channel 17 reserved on the housing 16. After the chemical reagents are filled, the reagent channel 17 is sealed with a sealing plug 18. The heating wire 11 passes through the sealing plug 18 and is inserted into the housing 16, and contacts the magnesium strip 12.

[0058] According to a preferred embodiment, Figure 3 A schematic diagram of another preferred structure of the hot-melt section 2 of the present invention is shown. Specifically, the signal line 9 is energized by the controller 5, and the energized signal line 9 breaks down the glycerin bottle 19, causing the glycerin inside the glycerin bottle 19 to react with the potassium permanganate 20 pre-sealed in the shell 16 and release heat. The heat from the reaction between the glycerin and the potassium permanganate 20 activates or ignites the igniter 13, which in turn ignites the thermite 14, causing the thermite 14 to undergo a strong thermite reaction, thereby forming a molten metal with ultra-high temperature. This molten metal eventually contacts and melts the anchor cable bundle 1, thus achieving the recovery of the anchor cable bundle 1. In particular, Figure 2 The sealing plate 15 shown can be made of thin iron plate, or can be replaced by other materials with higher strength but not heat resistance, such as PPS material.

[0059] For ease of understanding, the working principle of a tunnel anchor cable based on a thermoplastic structure according to the present invention will be explained below.

[0060] When using the tunnel anchor cable based on the thermofusion structure of the present invention, the thermofusion part 2 is pre-assembled and secured to the anchor cable bundle 1. The anchor cable bundle 1 is lowered into the soil to be anchored through the borehole 7. During the use and retrieval of the anchor cable bundle 1, the stress change of the anchor cable bundle 1 can be monitored in real time by a monitoring unit composed of a strain sensor 8 and a controller 5. When the corresponding anchoring force of the anchor cable bundle 1 is less than the standard threshold or design strength, secondary grouting is performed on the anchoring section 3 of the anchor cable bundle 1 through a grouting unit composed of a grouting device 6 and a grouting channel 4, thereby enhancing or compensating for the corresponding anchoring force. In particular, when it is necessary to retrieve the anchor cable bundle 1 using the thermofusion part 2, the signal line 9 connected to the housing 16 can be energized by the controller 5 outside the borehole 7 to make the heating wire 11 connected to the signal line 9 work. Furthermore, the heating wire 11, when energized, rapidly ignites the magnesium strip 12 sealed inside the housing 16. The combustion of the magnesium strip 12 further ignites the igniter 13. The igniter 13 comes into contact with the thermite 14 and activates it. The thermite 14 undergoes a strong oxidation-reduction reaction under the combustion assistance of the igniter 13, releasing a large amount of heat and forming an ultra-high temperature molten metal. The molten thermite 14 melts and flows out the sealing plate 15 of the housing 16, and melts and breaks the anchor cable bundle 1 after contacting it, thereby realizing the recovery of the anchor cable bundle 1.

[0061] According to a preferred embodiment, existing thermofusion anchors typically involve energizing the thermofusion anchor to remove the core, and after the core removal is completed following the energization period, the steel strands are pulled out and recycled. However, existing thermofusion anchors rely on direct heating of the thermofusion anchor with an energized conductor to dismantle the core. Therefore, before the steel strand reaches the corresponding melting temperature or meets the corresponding recyclable yield strength, it requires a long period of continuous heating through the energized conductor to melt the anchor cable bundle 1. Thus, the recovery process of the anchor cable bundle 1 will consume a lot of time, especially requiring a large amount of preheating preparation time. Secondly, since the anchor cable bundle 1 is buried in deep underground space, and the heat transfer effect of underground soil is relatively poor, the long-term continuous heating of the anchor cable bundle 1 with an energized conductor may involve a continuous output of a stable large current. However, there are many uncertainties in underground space, and because the heat transfer line of the energized conductor is very long, it is very likely that the heat of the energized conductor cannot be effectively transferred to the anchor cable bundle 1 during the continuous heating of the anchor cable bundle 1 with an energized conductor. In particular, the energized conductor in underground space is prone to failure and damage, and it is also difficult to maintain the current output for a long time.

[0062] According to a preferred embodiment of the invention, in this embodiment, the energized wire only provides initial heat to activate the corresponding thermoplastic agent, while the melting of the anchor cable bundle 1 mainly relies on the extremely high temperature during the reaction of the thermoplastic agent. Specifically, when it is necessary to melt the anchor cable bundle 1 for its recovery, the signal line 9 can be energized by the controller 5 to activate the heating wire 11. Compared to directly using the heating wire 11 for continuous physical heat transfer to melt the anchor cable bundle 1, the heating wire 11 only needs to provide relatively low heat energy sufficient to ignite the magnesium strip 12. The subsequent melting of the anchor cable bundle 1 depends entirely on the chemical reaction of the thermoplastic agent, such as the magnesium strip 12, and the heat generated by the chemical reaction. Therefore, it is not necessary to continuously provide a large amount of heat energy through the heating wire 11. It can greatly reduce energy consumption and waste. When the magnesium strip 12 burns and further ignites the igniter 13, the igniter 13 burns and generates higher energy than the magnesium strip 12, which can ignite the thermite 14. The thermite 14 burns and forms a molten metal with ultra-high temperature (up to 2000℃~3000℃) through an oxidation-reduction reaction. The molten metal comes into contact with the anchor cable bundle 1 and melts it. At the same time, the tensioning equipment outside the borehole 7 pulls out the melted anchor cable bundle 1 to complete the recycling.

[0063] Preferably, the entire oxidation-reduction reaction process of the thermite 14 is very rapid and intense, releasing a large amount of heat instantaneously. Compared to continuous heating of the anchor cable bundle 1 via an electric conductor or heating wire 11, the thermite 14 can instantly raise the ambient temperature around the anchor cable bundle 1 to several thousand degrees Celsius through its own thermite reaction. This allows the entire process from energizing the heating wire 11 to the thermite reaction of the thermite 14 to be completed in an extremely short time, thus significantly improving the efficiency of the entire anchor cable recovery. Secondly, the main products of the thermite reaction are various metal oxides. After the anchor cable bundle 1 is melted by the thermite 14, the residual reaction products will not cause secondary damage to the anchor cable bundle 1, will not affect the use of the recovered steel strand, and the metal oxides produced by the thermite reaction are... The residue in the underground space will not damage the underground space structure. In addition, the entire oxidation-reduction reaction process of the thermite 14 is usually known and simple, with good sustainability. Compared with the continuous heating of the anchor cable bundle 1 by directly using a current-carrying wire and maintaining a continuous and stable output of the current-carrying wire, the thermite reaction of the thermite 14, once started, is almost unaffected by the surrounding environment. In contrast, the current-carrying wire in the complex and ever-changing underground space is more prone to instability due to many uncertainties. This will add unexpected difficulties and costs to the recovery of the anchor cable bundle 1. The thermite reaction of the thermite 14 can melt the anchor cable bundle 1 instantly, which not only improves the anchor cable recovery efficiency, but also greatly reduces the possibility of uncertainties, making the anchor cable recovery more stable.

[0064] On the other hand, the existing thermofusion structure of thermofusion anchors is usually designed and used in conjunction with the main structure of the anchor cable. Therefore, designing such thermofusion anchors will introduce high design and manufacturing costs. In this invention, the main body / carrier of the thermofusion structure is a hollow shell made of ceramic, which can withstand the ultra-high temperature generated during the aluminothermic reaction to prevent the molten aluminothermic agent 14 from flowing freely. Secondly, the material price of the ceramic shell is very low, and the manufacturing process is relatively simple, which will greatly reduce the production and processing cost of the entire anchor cable structure. In addition, the overall design of the thermofusion structure is simple. Its main body mainly serves as a carrier for the thermofusion agent. Therefore, the entire main body of the structure can be adapted to various types of anchor cables or anchor rods with slight modifications or adjustments, so that the thermofusion part 2 of this invention can be applied to different types of anchors without adding too many complex structures.

[0065] It should be noted that the specific embodiments described above are exemplary. Those skilled in the art can devise various solutions inspired by the disclosure of this invention, and these solutions all fall within the scope of this invention and its protection. Those skilled in the art should understand that this specification and its accompanying drawings are illustrative and not intended to limit the scope of the claims. The scope of protection of this invention is defined by the claims and their equivalents. This specification contains multiple inventive concepts; terms such as "preferredly," "according to a preferred embodiment," or "optionally" indicate that the corresponding paragraph discloses an independent concept. The applicant reserves the right to file divisional applications based on each inventive concept.

Claims

1. A tunnel anchor cable based on a thermoplastic structure, characterized in that: It should include at least a monitoring unit for monitoring the anchoring force of the anchor cable. The monitoring unit is installed on the anchor cable bundle (1) and includes at least a strain sensor (8) for monitoring and transmitting stress change data of the anchor cable bundle (1). The sampling period of the strain sensor (8) is set according to a preset strain amplitude corresponding to the stress change of the anchor cable bundle (1); It also includes a heat-fusion section (2) for anchor cable recovery, the heat-fusion section (2) being mechanically and / or electrically connected to the anchor cable bundle (1), wherein the heat-fusion section (2) has a housing (16) snapped into the anchor cable bundle (1), the housing (16) encapsulating a heat-fusion agent, and the heat-fusion agent comprising an activating component and a melting component; The tunnel anchor cables also include: A heating assembly is connected to the housing (16) and in physical contact with the activation component, the heating assembly including a signal line (9) and a heating wire (11). The controller (5) is used to control the heating assembly to physically heat the activation component, and is communicatively connected to the strain sensor (8). In the case where the heating component is controlled by the controller (5) to physically heat the activating component, the activating component can release a first chemical reaction heat based on the physical heating and ignite the melting component through the first chemical reaction heat. The melting component burns due to the first chemical reaction heat and releases a second chemical reaction heat, so that when the melting component contacts the anchor cable bundle (1), the melting component can melt the anchor cable bundle (1) through the second chemical reaction heat. The activation component encapsulated in the housing (16) includes a magnesium strip (12) and an igniter (13), and the melting component includes an aluminothermic agent (14). The magnesium strip (12) is in direct contact with the heating wire (11). When the heating wire (11) is controlled to work by the controller (5), the heating wire (11) transfers heat to the magnesium strip (12) to ignite it. The magnesium strip (12) ignites the igniter (13) and the aluminothermic agent (14) so ​​that the aluminothermic agent (14) is transformed into a molten state through an aluminothermic reaction. The hot melt reagent is filled into the housing (16) through the agent channel (17) of the housing (16), and the agent channel (17) is sealed by a shape-matched sealing plug (18), wherein the heating wire (11) passes through the sealing plug (18) and is inserted into the housing (16) and in physical contact with the magnesium strip (12); The anchor cable bundle (1) is equipped with a grouting part, which consists of a grouting device (6) and a grouting channel (4). The grouting channel (4) includes several grouting pipes disposed within the anchor cable bundle (1), and the grouting pipes are connected to the grouting device (6) located outside the borehole opening (7).

2. The tunnel anchor cable according to claim 1, characterized in that, The signal line (9) is electrically connected to the heating wire (11) and the controller (5), wherein at least a portion of the heating wire (11) is in physical contact with the activation component so as to ignite the activation component under the drive of the controller (5) and give it thermal energy for igniting the melting component.

3. The tunnel anchor cable according to claim 2, characterized in that, The housing (16) is clamped on one side of the anchor cable bundle (1) and is provided with a sealing plate (15) for encapsulating the hot melt agent. When the thermite (14) comes into contact with the igniter (13) and turns into a molten state, the thermite (14) melts the sealing plate (15) and flows out through the housing (16) to come into contact with the anchor cable bundle (1) and melt it.

4. The tunnel anchor cable according to claim 3, characterized in that, When the controller (5) determines that the anchoring force of the anchor cable bundle (1) is lower than the set threshold based on the stress change data of the strain sensor (8), secondary grouting is performed on the anchoring section (3) of the anchor cable bundle (1) through the grouting part.

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