A resin anchor agent stirring installation method

Abstract

The application provides a resin anchoring agent stirring installation method and belongs to the technical field of resin anchoring agent application.The application eliminates the hole wall free water film by compressing hot air to drive moisture for the drilling, pushes the integrated hollow anchor cable body, which is embedded with a fine-diameter exhaust pipe and a grouting pipe with a terminal installed one-way valve, into the hole and carries out variable speed stirring, the hole bottom gas continuously escapes to the hole opening along the fine-diameter exhaust pipe through the one-way valve in the stirring pushing process, the constant tension is achieved by using the constant torque winding gun to complete the grouting strip winding and the grouting plug installation, the coaxial installation of the tray and the anchor and the single pre-tightening are sequentially completed, and finally the prestress control value is achieved through three-stage grading tensioning locking, so that the technical problem that the hole bottom gas cannot be effectively discharged in the resin anchoring agent stirring installation process and the bubble pore defects are formed in the solidified body is solved.

Description

Technical Field

[0001] This invention belongs to the field of resin anchoring agent application technology, and more specifically, relates to a method for mixing and installing resin anchoring agents. Background Technology

[0002] Resin anchoring cable support technology is widely used in the reinforcement of surrounding rock in coal mine roadways, tunnels, and underground spaces. It involves injecting resin anchoring agent into a pre-drilled hole and mixing and curing it, forming an integrated load-bearing system between the anchor cable and the surrounding rock. In current technology, anchoring construction typically involves manually pushing the anchor cable to the bottom of the hole while simultaneously rotating and mixing it. Operators rely on experience to control the mixing speed and pushing speed, and manually wrapping grout-stopping strips to seal the hole opening. Because current construction methods lack an internal venting channel, the gas in the enclosed space at the bottom of the hole is gradually compressed during the anchor cable insertion process. This compression forms air bubbles during the resin anchoring agent mixing and curing process. These air bubbles create continuous or discrete pore defects within the cured material, significantly reducing the density of the cured material and the chemical bonding area between the resin anchoring agent and the rock wall, making it difficult to achieve the designed anchoring load-bearing capacity. In other words, current technology suffers from the technical problem of ineffective gas release from the bottom of the hole during resin anchoring agent mixing and installation, leading to the formation of air bubble pore defects within the cured material. Summary of the Invention

[0003] In view of this, the present invention provides a resin anchoring agent mixing and installation method, which can solve the technical problem in the prior art where gas at the bottom of the hole cannot be effectively discharged during the resin anchoring agent mixing and installation process, resulting in the formation of air bubble pore defects in the cured body.

[0004] This invention is implemented as follows: This invention provides a method for mixing and installing resin anchoring agents, comprising the following steps:

[0005] Drilling inspection and compressed hot air dehumidification: After measuring the drilling depth to the design depth, first use compressed air to clean the dust in the borehole, and then continuously introduce compressed hot air into the borehole to dehumidify it for a period of not less than 60 seconds, so as to obtain a clean borehole with no free water film on the borehole wall.

[0006] Integrated hollow anchor body assembly: The fine-diameter exhaust pipe and grouting pipe are embedded into the reserved groove on the inner wall of the anchor body sheath. The outer diameter of the fine-diameter exhaust pipe does not exceed 4mm. A one-way valve is installed at the end of the fine-diameter exhaust pipe to complete the integrated hollow anchor body assembly.

[0007] Variable speed mixing and pushing of resin anchoring agent: After the resin anchoring agent is sent into the bottom of the clean borehole, the integrated hollow anchor cable body is sent into the clean borehole. First, the film is broken by rotating at a low speed, and then the speed is increased to a high speed to fully mix. During the pushing process, the gas at the bottom of the hole continuously escapes to the hole opening through the one-way valve along the narrow diameter exhaust pipe, thus completing the variable speed mixing and pushing of the resin anchoring agent.

[0008] Quantitative winding of grout stop strip and installation of grout stop plug: After removing the agitator, insert the grout stop strip into the constant torque winding gun. The constant torque winding gun automatically winds the preset number of turns in a counterclockwise direction with constant tension and then stops and emits a prompt sound. Then, push in the grout stop plug in sequence and tighten it with the push tube to obtain a sealed and clean drill hole.

[0009] Installation of the anchor tray and anchor and single pre-tightening: The anchor tray and anchor are coaxially installed on the integrated hollow anchor body in the sealed and clean drilled hole. There is no gap between the anchor tray and the contact surface. After the anchor is locked, the deviation does not exceed ±5°. After the resin anchoring agent is cured, 5% of the prestress control value is applied to each steel strand for single pre-tightening to make the initial straightening of each steel strand consistent, and the pre-tightened anchor is obtained.

[0010] Staged tensioning and locking: The tensioning machine applies prestress to the pre-tightened anchor cable in stages, and locks it after the tensioning force reaches the prestress control value.

[0011] Specifically, the compressed hot air dehumidification refers to continuously introducing heated compressed air into the borehole after dust removal, using the evaporation effect of the hot air to remove free water and water film from the borehole wall, preventing the water film from blocking the chemical bonding between the resin anchoring agent and the rock.

[0012] Specifically, the narrow-diameter exhaust pipe refers to a hollow air guide pipe with an outer diameter of no more than 4mm, embedded in a pre-reserved groove in the inner wall of the anchor cable sheath, used to continuously exhaust the sealed gas at the bottom of the hole to the hole opening during the process of pushing the integrated hollow anchor cable and the variable-speed stirring and pushing of the resin anchoring agent.

[0013] Specifically, the one-way valve refers to a flow control element installed at the end of the narrow-diameter exhaust pipe, which only allows the gas at the bottom of the hole to flow unidirectionally towards the orifice, and prevents the resin anchoring agent from flowing in the opposite direction towards the narrow-diameter exhaust pipe.

[0014] Specifically, the integrated hollow anchor body refers to the overall anchor structure formed by simultaneously embedding the fine-diameter vent pipe and the grouting pipe into the reserved groove on the inner wall of the anchor body sheath. Its outer diameter is the same as that of a conventional anchor body, and it has the functions of anchoring and bearing, venting in the hole and grouting.

[0015] Specifically, the variable-speed stirring of the resin anchoring agent refers to the initial stage of low-speed rotation at 60r / min for 10s to break the film and allow the curing agent to initially contact the resin, followed by increasing the speed to 120r / min for thorough mixing. The total stirring time is 30±5s, and the pushing speed does not exceed 20mm / s.

[0016] The constant torque winding gun is a handheld tool that automatically applies a constant tension of 15N to wind the grout-stopping strip for 8 turns in a counterclockwise direction after the strip is inserted. It then stops automatically and emits a prompt sound to ensure that the grout-stopping strip is wound with consistent density at each location.

[0017] Specifically, the single-strand pre-tensioning refers to applying a 5% prestress control value to each steel strand before tensioning all the steel strands as a whole, so that the initial straightening of each steel strand is consistent, thereby ensuring that each steel strand is subjected to uniform force during overall tensioning.

[0018] Specifically, the graded tensioning and locking step involves using an MQ22-450 / 63 tensioning machine to apply prestress in three stages: 50kN, 100kN, and 150kN. The prestress control value is 150kN. The pressure is stabilized for 5 minutes for each of the first two stages and for 15 minutes for the third stage. The tensioning stroke is 200mm, and the working oil pressure is 63MPa.

[0019] In the drilling inspection and compressed hot air dehumidification steps, the dehumidification time is not less than 60 seconds. After the dehumidification is completed, a clean borehole with no free water film on the borehole wall is obtained to ensure the chemical bonding area between the subsequent resin anchoring agent and the borehole wall.

[0020] In the steps of installing the tray and anchor and pre-tightening a single anchor, the deviation of the anchor after locking shall not exceed ±5°, and pre-tightening of a single anchor can only be carried out after the resin anchoring agent has cured for no less than 1 hour.

[0021] In the steps of quantitative winding of the grout-stopping strip and installation of the grout-stopping plug, the grout-stopping plug is pushed in and then tightened with a push tube to form a sealed clean borehole to withstand the subsequent grouting pressure.

[0022] The grouting pipe and the narrow-diameter exhaust pipe are simultaneously embedded into the reserved groove on the inner wall of the anchor cable sheath. The grouting pipe is used to inject grout into the hole after the resin anchoring agent has cured, so as to fill the gap formed by curing shrinkage.

[0023] Specifically, the absence of gaps between the anchor cable tray and the contact surface means that there are no gaps between the anchor cable tray and the rock surface or pad during installation, so as to ensure that the prestress is uniformly transmitted to the surrounding rock along the axial direction.

[0024] Before the variable-speed mixing and pushing step of the resin anchoring agent, there is also a step of re-measuring the diameter and depth of the clean drill hole. The resin anchoring agent can only be sent in after confirming that the diameter and depth meet the design requirements.

[0025] This invention addresses the problem of gas trapped at the bottom of the hole being continuously discharged to the orifice via a one-way valve through a pre-reserved groove in the inner wall of the integrated hollow anchor body. During the pushing of the anchor body and the variable-speed mixing and pushing of the resin anchoring agent, the gas trapped at the bottom of the hole is continuously discharged through the one-way valve along the narrow-diameter exhaust pipe to the orifice opening, preventing air bubbles from accumulating within the cured body. The outer diameter of the narrow-diameter exhaust pipe does not exceed 4mm, thus not altering the outer diameter of the integrated hollow anchor body and not affecting the mixing space between the anchor body and the orifice wall. The one-way valve allows gas to flow only in one direction towards the orifice opening, preventing the resin anchoring agent from entering the exhaust pipe in the reverse direction and causing blockage, ensuring the exhaust channel remains unobstructed throughout the mixing process. In summary, this invention solves the technical problem mentioned in the background art where gas at the bottom of the hole cannot be effectively discharged during the mixing and installation of the resin anchoring agent, leading to air bubble pore defects within the cured body. Attached Figure Description

[0026] Figure 1 This is a flowchart of the method of the present invention.

[0027] Figure 2 This is a schematic diagram of an integrated hollow anchor cable structure.

[0028] Figure 3 The graph shows the changes in rotation speed and propulsion speed over time during the variable-speed mixing and pushing process of the resin anchoring agent. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0030] like Figure 1 The diagram shows a flowchart of a resin anchoring agent mixing and installation method provided by the present invention. This method includes the following steps:

[0031] S10. Drilling inspection and compressed hot air dehumidification: After measuring the drilling depth to the design depth, first use compressed air to clean the dust in the drilling hole, and then introduce compressed hot air into the drilling hole to continuously dehumidify it. The dehumidification time is not less than 60 seconds, and a clean drilling hole with no free water film on the hole wall is obtained.

[0032] S20. Assembly of integrated hollow anchor body: Embed the small-diameter exhaust pipe and grouting pipe into the reserved groove on the inner wall of the anchor body sheath. The outer diameter of the small-diameter exhaust pipe shall not exceed 4mm. Install a one-way valve at the end of the small-diameter exhaust pipe to complete the assembly of the integrated hollow anchor body.

[0033] S30. Variable speed mixing and pushing of resin anchoring agent: After the resin anchoring agent is sent to the bottom of the clean borehole described in S10, the integrated hollow anchor body described in S20 is sent into the clean borehole. First, the film is broken by rotating at a low speed of 60r / min for 10s, and then the speed is increased to 120r / min to mix thoroughly. The total mixing time is 30±5s, and the pushing speed does not exceed 20mm / s. During the pushing process, the gas at the bottom of the hole continuously escapes to the hole opening through the one-way valve described in S20 and the narrow diameter exhaust pipe described in S20, thus completing the variable speed mixing and pushing of resin anchoring agent.

[0034] S40. Quantitative winding of the grout stop strip and installation of the grout stop plug: After removing the agitator, insert the grout stop strip into the constant torque winding gun. The constant torque winding gun automatically winds 8 turns in a counterclockwise direction with a constant tension of 15N and then stops and emits a prompt sound. Then, push in the grout stop plug in sequence and tighten it with the push tube to obtain a sealed and clean drill hole.

[0035] S50. Installation of the tray and anchor and single pre-tightening: Install the anchor tray and anchor coaxially onto the integrated hollow anchor body described in S20 into the sealed and cleaned borehole described in S40. There should be no gap between the anchor tray and the contact surface. After the anchor is locked, the deviation should not exceed ±5°. After the resin anchoring agent has cured for 1 hour, apply 5% of the prestress control value to each steel strand for single pre-tightening to make the initial straightening of each steel strand consistent, and obtain the pre-tightened anchor.

[0036] S60, Graded tensioning and locking: Using an MQ22-450 / 63 tensioning machine, prestress is applied to the anchor cable that has been pre-tensioned as described in S50 in three stages: 50kN, 100kN, and 150kN. The prestress control value is 150kN. The pressure is stabilized for 5 minutes for each of the first two stages and for 15 minutes for the third stage. The tensioning stroke is 200mm, the working oil pressure is 63MPa, and the tension is locked after the tension reaches the prestress control value of 150kN.

[0037] Among them, compressed hot air dehumidification refers to continuously introducing heated compressed air into the borehole after dust removal, using the evaporation effect of hot air to remove free water and water film from the borehole wall, preventing the water film on the borehole wall from blocking the chemical bond between the resin anchor and the rock, thereby ensuring the effective bonding strength of the resin anchor.

[0038] A narrow-diameter exhaust pipe refers to a hollow air guide pipe with an outer diameter of no more than 4 mm that is embedded in the inner wall of the anchor cable sheath and has a reserved groove. It is used to continuously exhaust the sealed gas at the bottom of the hole to the hole opening during the process of pushing the integrated hollow anchor cable and pushing the resin anchoring agent by variable speed stirring, so as to avoid air bubbles being trapped in the solidified body and forming pore defects.

[0039] A one-way valve is a flow control element installed at the end of a narrow-diameter exhaust pipe. It only allows gas at the bottom of the orifice to flow in one direction towards the orifice, preventing the resin anchoring agent from flowing in the opposite direction towards the narrow-diameter exhaust pipe and thus preventing blockage of the narrow-diameter exhaust pipe.

[0040] Integrated hollow anchor cable body refers to the overall anchor cable structure formed by simultaneously embedding a small-diameter vent pipe and a grouting pipe into the reserved groove in the inner wall of the anchor cable body sheath. The outer diameter is the same as that of a conventional anchor cable body, and it has the functions of anchoring and bearing, venting in the hole and grouting.

[0041] Variable speed mixing of resin anchoring agent refers to the operation method of controlling the rotation speed in stages during the mixing process of resin anchoring agent: in the initial stage, the outer film of the cartridge is broken by low speed to allow the curing agent to come into initial contact with the resin; then the speed is increased to fully mix the two components, thereby improving the mixing uniformity and allowing the curing strength to reach the design value.

[0042] A constant torque winding gun is a handheld tool. After the operator inserts the grout-stopping strip, the constant torque winding gun automatically applies a constant tension in a counterclockwise direction and winds it. It automatically stops and emits a prompt sound after reaching the preset number of turns. This is used to ensure that the grout-stopping strip is wound with consistent density at each location, eliminating the sealing failure problem caused by differences in manual judgment.

[0043] Single strand pretensioning refers to applying 5% of the prestress control value to each steel strand before tensioning all the steel strands as a whole, so that the initial straightening of each steel strand is consistent, thereby ensuring that the steel strands are subjected to uniform force during overall tensioning and preventing the situation where the stress of some steel strands exceeds the limit while the stress of the other steel strands has not yet reached the prestress control value.

[0044] The specific implementation of step S10 is as follows: First, the borehole depth is measured using a depth gauge or laser rangefinder. After confirming that the borehole depth has reached the designed depth, the cleaning process begins. The cleaning process uses pressurized air to positively blow away residual dust inside the borehole. The blowing time is generally no less than 20 seconds, until no dust overflows from the borehole opening, to eliminate the physical barrier of dust to the subsequent bonding between the resin anchoring agent and the borehole wall. After dust removal, heated compressed air (i.e., compressed hot air) is immediately introduced into the borehole for a continuous blowing time of no less than 60 seconds. The principle of compressed hot air dehumidification is based on the thermodynamic property that the relative humidity of the hot air is lower than the saturated vapor pressure of the free water on the borehole wall. This causes the free water in the water film on the borehole wall to migrate into the airflow by evaporation, thereby removing the free water and water film from the borehole wall surface. If the water film on the borehole wall is not removed, it will form a water film isolation layer during the curing process of the resin anchoring agent, blocking the covalent bonds or hydrogen bonds and other chemical bonds between the cured resin and the rock / mineral surface, resulting in a significant decrease in interfacial bonding strength. The reference threshold for dehumidification time is 60 seconds, which can be appropriately extended to 90–120 seconds in high-humidity or fractured formations. After dehumidification, the borehole wall surface should be dry, with no visible water droplets or water film, thus obtaining a clean borehole without a free water film on the borehole wall, creating interfacial conditions for the effective chemical bonding of the subsequent resin anchoring agent.

[0045] The specific implementation of step S20 is as follows: The assembly of the integrated hollow anchor body is carried out outside the borehole. During assembly, the small-diameter vent pipe and the grouting pipe are first embedded into the reserved channels in the inner wall of the anchor body sheath. The reserved channels are arranged along the entire axial length of the anchor body to ensure that the small-diameter vent pipe and the grouting pipe form an integrated structure with the anchor body, do not protrude from the outer diameter outline of the anchor body, and do not affect the insertion and rotational mixing of the anchor body in the borehole. The outer diameter of the small-diameter vent pipe does not exceed 4mm. This size limitation is based on the balance between the embedding stability of the small-diameter pipe in the sheath channel and the venting flow requirement: if the outer diameter is too large, it will occupy the mixing space and affect the flow of the anchoring agent; if the outer diameter is too small, the airflow resistance inside the pipe will increase, which is not conducive to the rapid escape of gas from the bottom of the borehole. The small-diameter vent pipe is made of high-density polyethylene or nylon material that is resistant to resin chemical corrosion to ensure that it will not deform or become blocked in the exothermic environment of resin curing. A one-way valve is installed at the end of the narrow-diameter vent pipe. The reference value for the opening pressure threshold of the one-way valve is 0.02-0.05 MPa. This ensures that the gas at the bottom of the borehole will automatically open and escape once the pressure reaches a certain level. The resin anchoring agent, under normal pressure, is insufficient to overcome the closing force of the one-way valve, thus preventing the resin anchoring agent from entering the narrow-diameter vent pipe in reverse. The end of the grouting pipe is sealed for future grouting. After assembly, the overall outer diameter of the integrated hollow anchor body is checked to ensure it matches that of a conventional anchor body; once confirmed, the assembly is complete.

[0046] The specific implementation of step S30 is as follows: First, the resin anchoring agent cartridges are sequentially fed into the bottom of the clean drilled hole according to the designed quantity. The cartridges are fed in by manual pusher or pneumatic pusher to ensure that the cartridges reach the bottom of the hole without being damaged. Then, the integrated hollow anchor cable body is connected to the stirring drive equipment and fed into the drill hole. The stirring process adopts a variable speed control strategy: In the initial stage, the film is broken by rotating at a low speed of 60 r / min for 10 seconds. The principle of low speed film breaking is to generate shear force on the outer film of the resin anchoring agent cartridge at the end of the anchor cable body, breaking the outer film and allowing the curing agent to initially contact the resin matrix. The low speed in this stage is to prevent the cartridge from being displaced as a whole due to high speed rotation in the unbroken state, and to avoid uneven mixing of the cartridge components. After the film breaking is completed, the speed is increased to 120 r / min for thorough mixing. The high speed makes the two components evenly dispersed under shear and convection. The total stirring time is controlled at 30±5 seconds, and the pushing speed does not exceed 20 mm / s. During the entire pushing process, the original sealed gas at the bottom of the hole is compressed by the advancement of the anchor cable body, and the pressure rises to exceed the opening pressure threshold of the one-way valve. The gas then automatically enters the narrow-diameter exhaust pipe through the one-way valve and continues to escape to the hole opening along the exhaust pipe, realizing the real-time discharge of gas at the bottom of the hole and preventing air bubbles from being trapped in the curing resin matrix and forming pore defects.

[0047] Specifically, the resin anchoring agent is stirred at varying speeds in two stages. The first stage involves stirring at a certain speed. Rotation, time is The membrane rupture is completed in the first stage; the second stage is achieved by rotating at a certain speed. Rotation, time is Complete mixing, total mixing time The calculation formula is expressed as follows:

[0048] ;

[0049] In the formula, The time for the low-speed membrane rupture stage is set to 10 seconds. This represents the duration of the high-speed mixing phase, measured in seconds (s). This refers to the total mixing time, ranging from 25 to 35 seconds. The reference time is set to 1 second for dimensionless processing. First stage rotational speed. The value is 60 r / min, the second stage rotation speed. The value is set at 120 r / min, and the propulsion speed does not exceed 20 mm / s. During the pushing process, the sealing gas at the bottom of the hole continuously escapes to the hole opening through a one-way valve and a narrow-diameter exhaust pipe, preventing air bubbles from being trapped in the solidified body and forming pore defects.

[0050] The specific implementation of step S40 is as follows: After mixing is completed, the mixing drive equipment is removed, and the integrated hollow anchor cable body remains stationary. The grout-stopping strip winding process is then immediately performed. The grout-stopping strip is inserted into the feed port of the constant torque winding gun. The constant torque winding gun has a built-in torque control mechanism that automatically winds the grout-stopping strip with a constant tension of 15N counterclockwise according to preset parameters. The counterclockwise winding direction is consistent with the subsequent anchor tightening direction to prevent loosening during anchor installation. The constant tension of 15N is based on the elastic deformation characteristics of the grout-stopping strip material. This tension value allows the grout-stopping strip to generate sufficient radial shrinkage prestress during winding, forming a tight radial contact seal with the borehole wall when pushed into the borehole. The constant torque winding gun automatically stops and emits a prompt sound after reaching the preset number of 8 turns. After receiving the prompt, the operator confirms that the winding is complete. There is no need for manual judgment of the winding density, eliminating the problem of inconsistent winding tightness caused by individual differences in traditional manual winding. After the winding is completed, the grout stop plugs are pushed into the borehole in sequence. The outer diameter of the grout stop plug matches the inner diameter of the borehole. After being pushed in, the grout stop plugs are tightened axially with the push tube to form a double seal with the grout stop strip, thereby obtaining a clean borehole after sealing, which provides pressure conditions for subsequent grouting.

[0051] The specific implementation of step S50 is as follows: After sealing, the anchor cable tray is inserted into the integrated hollow anchor cable body and pushed along the axial direction of the anchor cable body until it contacts the surrounding rock surface or pad. It is confirmed that there are no gaps between the anchor cable tray and the contact surface, ensuring that the subsequent prestress can be evenly transferred to the surrounding rock interface through the tray. Then, the anchor is installed. After the anchor is locked, its axial deviation needs to be checked. The allowable deviation range is ±5°. Exceeding this limit will cause bending stress concentration in the steel strand at the anchor, affecting the tension bearing capacity. After the resin anchoring agent has cured for 1 hour, the single-strand pre-tightening process begins. Single-strand pre-tightening uses a small-tonnage tensioning device to apply a pre-tightening force of 5% of the prestress control value to each steel strand. Under this pre-tightening force, each steel strand completes its initial elastic straightening, eliminating uneven initial relaxation caused by manufacturing deviations, differences in curvature during cable threading, and other factors. After the pretensioning of a single strand is completed, the initial straightening of each steel strand tends to be consistent, which provides the prerequisite for the synchronous stress of each steel strand during the subsequent overall tensioning, and obtains the anchor cable with pretensioning completed.

[0052] Specifically, after the resin anchoring agent has cured for 1 hour, each steel strand is individually pre-tightened by applying 5% of the prestress control value. The calculation formula is expressed as follows:

[0053] ;

[0054] In the formula, This represents the preload force per single strand, expressed in kN. The prestress control value is set at 150 kN. For reference force, a value of 1kN is used for dimensionless processing. Individual pre-tensioning ensures consistent initial straightening of each steel strand, guaranteeing uniform stress distribution during overall tensioning. This prevents situations where localized strand stress exceeds limits while other strands have not yet reached prestress control values, resulting in a pre-tensioned anchor cable.

[0055] The specific implementation of step S60 is as follows: The pre-tensioned anchor cable is tensioned in stages using an MQ22-450 / 63 tensioning machine. A three-stage loading regime is adopted, applying prestress at 50kN, 100kN, and 150kN sequentially, with a prestress control value of 150kN. The principle of staged loading is to gradually increase the load so that each load-bearing component in the anchoring system enters an elastic stress state sequentially, avoiding sudden failure of the anchoring agent interface or the steel strand anchoring section due to local stress concentration when loading to the control value all at once. The first two stages are stabilized for 5 minutes each, during which the oil pressure of the tensioning machine is observed to see if there is a significant drop. If the oil pressure drops beyond the set threshold, the anchoring quality needs to be assessed and remedial measures taken. The third stage is stabilized for 15 minutes; the longer stabilization time is to fully verify the creep characteristics and interface stability of the anchor body under the prestress control value. The tensioning stroke is 200mm, the working oil pressure is 63MPa, and the tension is locked after reaching the prestress control value of 150kN. After locking, the anchor and the exposed section of the steel strand are treated with anti-corrosion to complete the entire installation process.

[0056] Specifically, tension at each level The formula for the graded application method is expressed as follows:

[0057] ;

[0058] In the formula, For the first Tension force, unit is kN. The values ​​are 1, 2, and 3; This is the increment value, which is 50kN. For reference, a value of 1 kN is used for dimensionless processing. The tension is locked after reaching the prestress control value of 150 kN, completing the staged tensioning and locking. The purpose of staged tensioning is to avoid impact damage to the anchor body and rock mass caused by a single loading, and to gradually and evenly distribute the stress in each component through step-by-step pressure stabilization, thereby improving the overall reliability of the anchoring system.

[0059] It should be noted that one of the key technical concepts of this invention is the active venting mechanism within the hole, consisting of a narrow-diameter vent pipe and a one-way valve. In traditional anchor installation, the process of pushing the anchor body in is equivalent to piston movement within a closed cavity. The gas at the bottom of the hole is passively compressed and trapped in the solidified body in the form of bubbles, which cannot be eliminated through external intervention. This invention provides a unique low-resistance escape channel for the gas at the bottom of the hole by embedding a narrow-diameter vent pipe in a pre-reserved groove in the inner wall of the anchor body sheath and installing a one-way valve at the end. The flow direction control characteristics of the one-way valve also prevent the resin anchoring agent from backflowing and clogging the vent pipe, ensuring that the venting process continues effectively throughout the entire mixing and pushing stage.

[0060] The second key technological approach is the pretreatment of the pore wall interface by compressed hot air dehumidification. The presence of a water film blocks the chemical bonding between the cured resin molecules and the functional groups on the surface of the rock minerals through physical isolation. The hot air evaporation principle can completely eliminate the free water film without damaging the pore wall structure, restore the chemical activity of the rock surface, and form an effective interfacial bonding layer between the cured resin and the pore wall.

[0061] The third key technological approach is the constant tension and quantitative winding of the sealant strip achieved by the constant torque winding gun. Traditional manual winding results in uneven sealing pressure due to differences in operator feel. The constant torque winding gun uses mechanical torque control to fix the winding tension at 15N and the number of turns at 8, transforming the sealing quality from a human judgment to quantifiable mechanical control parameters, thus eliminating the randomness of seal failure.

[0062] The three technical approaches described above work synergistically in this invention: hot air dehumidification ensures the material basis for interfacial chemical bonding, the active exhaust mechanism eliminates pore defects within the solidified body, and quantitative sealing ensures the effective maintenance of grouting pressure. These three aspects act on the three dimensions of interface quality, volumetric density, and sealing reliability, supporting each other and jointly ensuring the overall quality of the solidified body from the microscopic interface to the macroscopic mechanical properties.

[0063] It should be noted that this invention also solves the following technical problems: In existing resin anchor cable installation, the manual winding of the grout-stopping strip relies on the operator's personal experience and feel, and the number of winding turns and tension vary from person to person. Significant differences in winding density exist between different operators on the same construction surface or even among the same operator under fatigue conditions, leading to sealing failure at some hole positions, leakage of grout from the hole opening, failure to establish grout pressure, and inability of the anchoring agent to fill the hole space. This invention, through a constant torque winding gun, automatically winds 8 turns counterclockwise at a constant tension of 15N and issues a prompt sound upon completion. This transforms the grout-stopping strip winding operation from relying on manual experience to mechanical parameter control, eliminating the impact of human operational differences on sealing quality and solving the technical problem of inconsistent winding density leading to sealing failure.

[0064] This invention also solves the technical problem of uneven stress during the overall tensioning of multiple steel strand anchor cables due to inconsistent initial relaxation of each strand. In existing construction, after multiple steel strands are threaded through the cable, the initial free elongation of each strand varies due to the curvature of the threading, friction, and manufacturing deviations. During overall tensioning, the strand that is stressed first reaches its stress limit first, while the remaining strands are still in a low-stress state, resulting in the inability to reach the prestress control value simultaneously, leading to local over-tensioning or overall under-tensioning. This invention applies a single preload of 5% of the prestress control value to each steel strand before overall tensioning, ensuring that each strand has completed its initial elastic straightening before entering the overall tensioning stage, and that the initial straightening is more consistent. This guarantees that each steel strand is stressed synchronously and uniformly during subsequent staged tensioning, thus solving the technical problem of uneven stress distribution among multiple steel strands.

[0065] Specifically, the principle of this invention is as follows: the solution can solve the above-mentioned technical problems because the integrated hollow anchor body acts as a piston during the pushing process. The gas sealed at the bottom of the hole is continuously compressed. Without an exhaust channel, this gas would remain in the solidifying resin anchoring agent matrix as bubbles. The narrow-diameter exhaust pipe provides a low-resistance escape path for the gas at the bottom of the hole, and the one-way valve at the end ensures that the gas can only flow out unidirectionally along the exhaust pipe towards the hole opening, fundamentally cutting off the physical conditions for bubble formation within the solidified body. At the same time, the compressed hot air dehumidification step eliminates the obstruction of the free water film on the hole wall to the chemical bonding between the resin and the rock. The variable-speed stirring process ensures the uniformity of the two-component mixing. The constant-torque winding gun eliminates the human error in sealing the grout-stopping strip. Single-strand pre-tensioning and graded tensioning ensure uniform stress on each steel strand. The steps are logically sequential and mutually supportive, jointly ensuring the quality of the anchoring system throughout the entire process from hole wall bonding to overall load-bearing capacity. The solution has inherent technical consistency and rationality.

[0066] The following provides a specific embodiment 1 of the present invention, and the specific implementation of each step in this embodiment 1 is described in detail below.

[0067] To verify the effectiveness of the invention, technicians set up a test environment during the support construction of an underground tunnel. A tunnel section with medium-hardness sandstone as the surrounding rock was selected as the construction object. The borehole diameter was 28mm, the designed hole depth was 6000mm, and the anchor cable body was composed of 7 steel strands. The prestress control value was 150kN. The resin anchoring agent used was MSK28*500 fast-curing anchoring cartridge, and the nominal curing time was 1h. The relative humidity of the construction environment was 78%, which is a high humidity environment.

[0068] During the construction preparation phase, technicians first measured the borehole depth. After confirming the depth reached 6000mm, they used compressed air at 0.4MPa to positively purge dust from the borehole for 25 seconds. Cleaning was considered complete once no dust overflowed from the borehole opening. Subsequently, compressed hot air was introduced into the borehole, with the outlet temperature controlled at 60℃ for 90 seconds (higher than the minimum threshold of 60 seconds). Considering the high relative humidity of the construction environment, the dehumidification time was appropriately extended to fully remove the free water film from the borehole walls. Figure 3 As shown, after the dehumidification process is completed, there are no visible water droplets on the surface of the hole wall.

[0069] The assembly of the integrated hollow anchor body was carried out on an external platform. A 3.8mm outer diameter vent pipe and a grouting pipe were embedded into pre-reserved channels in the inner wall of the anchor body sheath. A one-way valve was installed at the end of the vent pipe, with an opening pressure of 0.03MPa. After the overall assembly was completed, the outer diameter of the anchor body was verified to be 28mm, with zero clearance to the borehole diameter, consistent with the outer diameter of conventional anchor bodies. Three rolls of MSK28*500 resin anchoring agent were pushed to the bottom of the borehole, and then connected to a mixing drive. The mixture was rotated at a low speed of 60r / min for 10s to break the film, then the speed was increased to 120r / min for thorough mixing. The total mixing time was 32s, and the pushing speed was controlled at 18mm / s. During the mixing and pushing process, continuous airflow was observed escaping through the outlet of the vent pipe, confirming normal gas discharge from the bottom of the borehole.

[0070] During the grout-stopping strip wrapping process, the operator inserts the strip into a constant-torque wrapping gun. The gun applies a constant tension of 15N counterclockwise and automatically wraps the strip for 8 turns, then emits a beeping sound. The entire process takes approximately 12 seconds. The operator does not need to judge the tightness of the strip. Afterward, the grout-stopping plug is pushed in and tightened with a push tube to complete the seal. A total of grout-stopping strips were wrapped at 8 holes in this construction project. The wrapping parameters for each hole are shown in Table 1.

[0071] Table 1 Record of Parameters for Grout Stopping Strips at Each Hole Location

[0072]

[0073] As shown in Table 1, after using a constant torque winding gun, the winding parameters of the 8 holes were completely consistent, and the sealing test results were all qualified, demonstrating the advantage of mechanical parameter control over manual experience judgment in terms of consistency.

[0074] After the resin anchoring agent cured for 1 hour, the tray and anchor were installed. The anchor tray was pushed until it contacted the rock surface at the borehole opening. Visual inspection showed no gaps. After the anchor was locked, the axial deviation was within ±3°, meeting the design requirement of no more than ±5°. During the single-strand pre-tightening stage, a pre-tightening force of 7.5kN (5% of the prestress control value of 150kN) was applied to each of the seven steel strands sequentially. The elongation of each steel strand after pre-tightening is shown in Table 2.

[0075] Table 2 Record of Pre-tension Elongation of Individual Steel Strands

[0076]

[0077] As shown in Table 2, the elongation of each of the seven steel strands after pretensioning is concentrated in the range of 3.1 to 3.3 mm, and the initial straightening is consistent, which lays the foundation for uniform stress on each steel strand during subsequent graded tensioning.

[0078] The graded tensioning stage used an MQ22-450 / 63 tensioning machine, with a three-stage loading regime: 50kN for 5 minutes, 100kN for 5 minutes, and 150kN for 15 minutes. During each loading stage, the hydraulic pressure remained stable without significant drop. The final tension force reached 150kN and was locked. The tensioning stroke was 198mm, and the working hydraulic pressure was 62.8MPa, all within the design range. The tensioning parameters and loading status for each stage are as follows: Figure 3 As shown.

[0079] The technological advancements of this invention compared to traditional methods are reflected in the following aspects: Regarding interface bonding quality, the compressed hot air dehumidification method completely eliminates the free water film on the pore walls through thermodynamic evaporation, restoring the chemical activity of the rock surface. This allows the resin to form effective chemical bonds with the pore walls at the molecular level after curing, whereas traditional methods rely on natural drying or simply using pressurized air to blow away moisture, failing to eliminate the water film formed by capillary adsorption. Regarding the density of the cured body, the active venting mechanism composed of a narrow-diameter vent pipe and a one-way valve fundamentally cuts off the physical channels for air bubbles to form within the cured body. Traditional methods lack venting means, making the existence of air bubble pores within the cured body inevitable. Regarding sealing reliability, the constant torque winding gun transforms the winding tension and number of turns of the grout-stopping strip into controllable mechanical parameters, eliminating the randomness of manual operation and ensuring repeatable sealing quality. Regarding prestress uniformity, the single-strand pre-tightening step eliminates the initial relaxation differences among the steel strands, allowing multiple steel strands to simultaneously enter the stress state during the graded tensioning process, ensuring the uniformity of prestress distribution from the stress mechanism perspective.

[0080] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for mixing and installing resin anchoring agent, characterized in that, Includes the following steps: Drilling inspection and compressed hot air dehumidification: After measuring the drilling depth to the design depth, first use compressed air to clean the dust in the borehole, and then continuously introduce compressed hot air into the borehole to dehumidify it for a period of not less than 60 seconds, so as to obtain a clean borehole with no free water film on the borehole wall. Integrated hollow anchor body assembly: The fine-diameter exhaust pipe and grouting pipe are embedded into the reserved groove on the inner wall of the anchor body sheath. The outer diameter of the fine-diameter exhaust pipe does not exceed 4mm. A one-way valve is installed at the end of the fine-diameter exhaust pipe to complete the integrated hollow anchor body assembly. Variable speed mixing and pushing of resin anchoring agent: After the resin anchoring agent is sent into the bottom of the clean borehole, the integrated hollow anchor cable body is sent into the clean borehole. First, the film is broken by rotating at a low speed, and then the speed is increased to a high speed to fully mix. During the pushing process, the gas at the bottom of the hole continuously escapes to the hole opening through the one-way valve along the narrow diameter exhaust pipe, thus completing the variable speed mixing and pushing of the resin anchoring agent. Quantitative winding of grout stop strip and installation of grout stop plug: After removing the agitator, insert the grout stop strip into the constant torque winding gun. The constant torque winding gun automatically winds the preset number of turns in a counterclockwise direction with constant tension and then stops and emits a prompt sound. Then, push in the grout stop plug in sequence and tighten it with the push tube to obtain a sealed and clean drill hole. Installation of the anchor tray and anchor and single pre-tightening: The anchor tray and anchor are coaxially installed on the integrated hollow anchor body in the sealed and clean drilled hole. There is no gap between the anchor tray and the contact surface. After the anchor is locked, the deviation does not exceed ±5°. After the resin anchoring agent is cured, 5% of the prestress control value is applied to each steel strand for single pre-tightening to make the initial straightening of each steel strand consistent, and the pre-tightened anchor is obtained. Staged tensioning and locking: The tensioning machine applies prestress to the pre-tightened anchor cable in stages, and locks it after the tensioning force reaches the prestress control value.

2. The resin anchoring agent mixing and installation method according to claim 1, characterized in that, The compressed hot air dehumidification specifically refers to continuously introducing heated compressed air into the borehole after dust removal, using the evaporation effect of the hot air to remove free water and water film from the borehole wall, preventing the water film from blocking the chemical bonding between the resin anchoring agent and the rock.

3. The resin anchoring agent mixing and installation method according to claim 2, characterized in that, The aforementioned fine-diameter exhaust pipe specifically refers to a hollow air guide pipe with an outer diameter not exceeding 4mm and embedded in a pre-reserved groove in the inner wall of the anchor cable sheath. It is used to continuously exhaust the sealed gas at the bottom of the hole to the hole opening during the process of pushing the integrated hollow anchor cable and the variable-speed stirring and pushing of the resin anchoring agent.

4. The resin anchoring agent mixing and installation method according to claim 3, characterized in that, The one-way valve specifically refers to a flow control element installed at the end of a narrow-diameter exhaust pipe, which only allows gas at the bottom of the hole to flow unidirectionally towards the orifice, and prevents the resin anchoring agent from flowing in the opposite direction towards the narrow-diameter exhaust pipe.

5. The resin anchoring agent mixing and installation method according to claim 4, characterized in that, The integrated hollow anchor body specifically refers to the overall anchor structure formed by simultaneously embedding the fine-diameter vent pipe and the grouting pipe into the reserved groove on the inner wall of the anchor body sheath. Its outer diameter is the same as that of a conventional anchor body, and it has the functions of anchoring and bearing, venting in the hole and grouting.

6. The resin anchoring agent mixing and installation method according to claim 5, characterized in that, The variable-speed stirring of the resin anchoring agent specifically refers to the initial stage of low-speed rotation at 60r / min for 10s to break the film and allow the curing agent to initially contact the resin, followed by increasing the speed to 120r / min for thorough mixing. The total stirring time is 30±5s, and the propulsion speed does not exceed 20mm / s.

7. The resin anchoring agent mixing and installation method according to claim 6, characterized in that, The constant torque winding gun is a handheld tool that automatically applies a constant tension of 15N to wind the grout-stopping strip for 8 turns in a counterclockwise direction after the strip is inserted. It then stops automatically and emits a prompt sound to ensure that the grout-stopping strip is wrapped with consistent density at each location.

8. The resin anchoring agent mixing and installation method according to claim 7, characterized in that, The single-strand pre-tensioning refers specifically to applying 5% of the prestress control value to each steel strand before tensioning all the steel strands as a whole, so that the initial straightening of each steel strand is consistent, thereby ensuring that the force on each steel strand is uniform during overall tensioning.

9. The resin anchoring agent mixing and installation method according to claim 8, characterized in that, The step of graded tensioning and locking is specifically to apply prestress in three stages: 50kN, 100kN, and 150kN using an MQ22-450 / 63 tensioning machine. The prestress control value is 150kN. The pressure is stabilized for 5 minutes for the first two stages and for 15 minutes for the third stage. The tensioning stroke is 200mm and the working oil pressure is 63MPa.

10. The resin anchoring agent mixing and installation method according to claim 9, characterized in that, In the drilling inspection and compressed hot air dehumidification steps, the dehumidification time shall not be less than 60 seconds. After the dehumidification is completed, a clean borehole with no free water film on the borehole wall is obtained to ensure the chemical bonding area between the subsequent resin anchoring agent and the borehole wall.

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