Numerical control double-shaft linkage test device and method for simulating square roadway excavation unloading

Abstract

The invention discloses a numerical control double-shaft linkage test device and method for simulating square roadway excavation unloading, and relates to the technical field of underground engineering excavation simulation tests, the numerical control double-shaft linkage test device comprises a cooling liquid injection hole, a sealing control valve and a drill bit motor base, and the upper end of the drill bit motor base is provided with a drill bit motor; the output end of the drill bit motor is provided with two sets of drill rods and a driving shaft, the sealing control valve is arranged at the front end of the drill bit motor, the drill rods are installed in the center of the sealing control valve, and a shaft support is arranged outside the drill rods. Through linkage control of a vertical lead screw motor, a horizontal lead screw motor and a drill bit motor and cooperation with an integrated regulation and control system of a control panel, accurate movement of a drill bit in the X-Z plane is achieved, the drilling direction, the drilling depth and the drill bit rotating speed can be accurately controlled, double-gear meshing is adopted to drive the square hole drill bit to do eccentric movement, and the drilling precision is improved. And excavation of the square roadway is achieved.

Description

Technical Field

[0001] This invention relates to the field of underground engineering excavation simulation test technology, specifically to a CNC dual-axis linkage test device and method for simulating the excavation and unloading of a square tunnel. Background Technology

[0002] With the gradual depletion of shallow resources and the development of national infrastructure, more and more mines, transportation tunnels, water conservancy and hydropower projects are moving towards deeper rock masses. This increased depth makes the environment of rock mass engineering increasingly complex, subject to high ground stress and dynamic disturbances caused by tunnel excavation unloading and blasting. This leads to frequent rockburst disasters, seriously threatening the safety of construction personnel and equipment, hindering project progress, and causing significant economic losses. In actual engineering, the stress process of deep rock masses can be described as "high stress + excavation unloading + dynamic disturbance." Currently, in indoor tests simulating the rockburst occurrence process and the failure characteristics of surrounding rock in tunnels, pre-cast borehole samples are commonly used—that is, excavation followed by loading tests. This method ignores the excavation process and the weakening effect of surrounding rock strength induced by excavation unloading, resulting in a stress path that differs from the actual stress process of rock in engineering. Furthermore, existing drilling equipment is typically circular, while in actual engineering, the cross-sectional shape of tunnels needs to be designed according to specific conditions; some tunnels are designed with square cross-sections. Therefore, to better study the failure process, characteristics, and mechanical properties of surrounding rock in square tunnels, a simulation test of the stress path "high stress + square hole excavation unloading + dynamic disturbance" on the samples is more closely related to actual engineering. Currently, existing experimental studies all involve drilling circular tunnels, while excavation unloading of square tunnels cannot be achieved. The main reason is that the market generally only produces drilling rigs and drill bits for drilling circular holes. Drilling square holes requires the Reuleaux triangle theorem to achieve a square profile tool trajectory during rotary cutting, which has a high technical threshold and high equipment cost, making it difficult to promote in engineering practice. In addition, existing experimental methods mostly focus on circular cross-section simulation and lack systematic research on the excavation response of non-circular cross-sections. The development of related processes and equipment is relatively lagging behind, so the excavation unloading process of square tunnels cannot yet be realized.

[0003] Therefore, in view of this, we studied and improved the existing structure and its shortcomings, and proposed a numerical control dual-axis linkage test device and method for simulating the excavation and unloading of a square tunnel. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a numerically controlled dual-axis linkage test device and method for simulating the excavation and unloading of square tunnels, thus solving the problems mentioned in the background art.

[0005] To achieve the above objectives, a first aspect of the present invention provides a CNC dual-axis linkage test device for simulating the excavation and unloading of a square tunnel, comprising a cooling injection hole, a sealing control valve, and a drill motor base. A drill motor is mounted on the upper end of the drill motor base, and a drill rod and a drive shaft are mounted on the output end of the drill motor. The sealing control valve is located at the front end of the drill motor, and a drill rod is mounted at the center of the sealing control valve. A shaft support is provided on the outside of the drill rod. Two sets of drill rods are provided, and gears are mounted on the outside of both sets of drill rods. A square-hole drill bit is mounted at the end of one set of gears, and two sets of gears are provided, with the two sets of gears meshing with each other. A sample is provided on one side of the square-hole drill bit. The cooling injection hole is opened inside the drill rod, and a cavity is provided at one end of the cooling injection hole. A pipe is installed at the top of the cavity, and a pneumatic slip ring is installed on the outside of the cavity. A support plate is installed at the bottom of the drill bit motor base, and a lead screw nut is provided at the bottom of the support plate. Two sets of lead screws are symmetrically arranged inside the lead screw nut, and a vertical lead screw motor is installed at the top of the lead screws through a coupling. A lead screw support is installed at the bottom of the lead screws, and a horizontal lead screw nut is provided at the bottom of the lead screw support. Two sets of horizontal lead screws are symmetrically arranged inside the horizontal lead screw nut, and a horizontal lead screw motor is installed at the end of the horizontal lead screws. A base plate is installed at the bottom of the horizontal lead screw motor. The drill bit motor, the vertical lead screw motor, and the horizontal lead screw motor are electrically connected to a control panel, and the control panel is electrically connected to a vertical lead screw motor controller, a drill bit motor controller, and a horizontal lead screw motor controller.

[0006] Furthermore, a mounting bracket is provided at the upper end of the drill bit motor base, and a lubrication frame is installed at the end of the mounting bracket.

[0007] Furthermore, an inner frame is provided on one side of the lubrication frame, and two sets of drill rods are installed inside the inner frame through a lip seal ring.

[0008] Furthermore, the two sets of gears are disposed inside the built-in frame, and a control component for controlling the flow is installed at the bottom of the built-in frame.

[0009] Furthermore, the control component includes a metal plug, a connecting spring, and a fixing plate, with a connecting spring provided on one side of the metal plug and a fixing plate installed at the end of the connecting spring.

[0010] Furthermore, the end of the drive shaft is provided with a heat dissipation component for auxiliary heat dissipation, and the heat dissipation component includes a connecting plate, blades and a dust cover. The surface of the connecting plate is circumferentially distributed with blades, and the connecting plate and blades are provided with a dust cover.

[0011] Furthermore, the dust cover has a hollow structure and a circular cross-section.

[0012] Furthermore, a cooling and lubrication system for auxiliary cooling is installed at the lower end of the metal plug. The cooling and lubrication system includes a cooling frame, a liquid level sensor, and a temperature sensor. The liquid level sensor is installed inside the cooling frame, and the temperature sensor is installed below the liquid level sensor.

[0013] Furthermore, the cooling and lubrication system also includes an oil pump and a conduit, and the bottom of the cooling frame is provided with a conduit, with an oil pump installed at the end of the conduit.

[0014] The second aspect of this invention provides a numerically controlled biaxial linkage test method for simulating the excavation and unloading of a square tunnel, comprising the following steps: Step 1: Install the CNC dual-axis linkage test device for simulating square tunnel excavation and unloading on the X-direction of the YD-SZ5000 deep multi-field coupled rock true triaxial excavation unloading-dynamic disturbance test system. The vertical direction is the Z-direction of the test machine, and the horizontal direction is the X and Y directions of the test machine. Fix the base plate of the device on the test system. By inputting commands on the control panel, turn on the vertical screw motor controller and the horizontal screw motor controller, and start the horizontal screw motor and the vertical screw motor. Through the coordinated movement of the horizontal screw and the vertical screw, adjust the position of the drill bit motor seat so that the drill bit is placed at the position of square tunnel excavation, so that the drill bit is accurately aligned with the predetermined opening position of the sample. Step 2: Fix the rock sample. Place the rock sample in the loading chamber of the testing machine, which consists of a vertical upper loading block, a vertical lower loading block, a horizontal left loading block, and a horizontal right loading block. The control system of the testing machine applies a small force in the vertical and horizontal directions to fix the rock sample. The forces in the horizontal and vertical directions are equal. Step 3: Apply two-dimensional loading to the rock specimen. After the rock specimen is fixed on the testing machine, apply vertical stress at the same loading rate. σ v and horizontal stress σ h The two-dimensional stress level applied to a set depth can simulate stress environments at different depths, and different stresses can be recorded through a monitoring system and a data acquisition system. Step 4: Start the drill motor to rotate the square hole drill bit and cut into the sample. Open the sealing control valve and inject liquid nitrogen into the cooling injection hole through the pipeline. The liquid nitrogen is then evenly introduced into the drill rod through the cavity to cool the drill bit. The drill rod is equipped with a spiral channel to discharge rock debris generated during the excavation of the square tunnel. When the drilling depth reaches the set position, turn off the liquid nitrogen injection switch and control the drill motor to move in the opposite direction through the horizontal screw motor controller, so that the square hole drill bit leaves the sample surface, completing the excavation and unloading simulation of the square tunnel. Then, turn off all motors. Step 5: Lubricating oil is pre-filled inside the built-in frame. The gears are immersed in the lubricating oil, which can absorb the heat generated when the two sets of gears mesh and lubricate at the same time. When the lubricating oil in the built-in frame absorbs heat to the preset value, the resistance of the thermistor increases and the current decreases, thereby reducing the magnetic force of the electromagnet. The electromagnet can then stop the magnetic attraction of the metal plug. The metal plug will be reset by the action of the connecting spring, so that the lubricating oil in the built-in frame will be introduced into the cooling frame. When the lubricating oil rises to the preset height, the liquid level sensor alarms. At the same time, when the temperature sensor in the cooling frame reaches the preset value, the oil pump can be started by the controller. Thus, the cooled lubricating oil can be replenished into the built-in frame through the conduit design to continue to cool and dissipate heat from the meshing gears. Step six: When the drill motor is started and the square hole drill bit is rotated to cut into the sample, the drive shaft and the connecting disc and blades connected to the drive shaft move accordingly. Through the high-speed rotation of the blades, the blades are designed to ensure that the air blows towards one end of the drill rod, which is used to dissipate heat from the drill motor and blow the dust generated during drilling and cutting away from the working area. This ensures that the dust is dispersed, heat is dissipated, and drilling and cutting proceed accordingly, and avoids the dust acting on the surface of the horizontal lead screw, which would affect the smoothness of the lateral movement. Step 7: Continue loading the rock samples from the excavated square tunnel, and use a miniature camera to observe and record the failure process and characteristics of the surrounding rock in the square tunnel. Combine the stress and displacement data during the failure process to evaluate the deformation characteristics and failure mechanism of the surrounding rock after excavation and unloading of the square tunnel, and provide experimental basis for the stability design of underground engineering.

[0015] Beneficial effects: 1. This invention achieves precise movement of the drill bit in the XZ plane through the linkage control of the vertical lead screw motor, the horizontal lead screw motor, and the drill bit motor, combined with the integrated control system of the control panel. It can accurately control the drilling orientation, depth, and drill bit rotation speed. It uses double gear meshing to drive the square hole drill bit to perform eccentric motion. Combined with liquid nitrogen synchronous cooling technology, liquid nitrogen is accurately delivered to the drill bit cutting surface through the cooling injection hole, which effectively reduces thermal damage and surrounding rock disturbance during the cutting process. It realistically reproduces the stress redistribution characteristics during the unloading of deep tunnel excavation. At the same time, the two-dimensional loading system can simulate the stress environment at different depths. A miniature camera is used to monitor and record the failure process and characteristics of the surrounding rock of the square tunnel in real time. Combined with real-time stress and strain data acquisition and analysis, it provides accurate and reliable experimental basis for the stability design of underground engineering.

[0016] 2. This invention employs a wrap-around design of a lubrication frame and an internal frame in the gear meshing area. The lubricating oil not only reduces wear during high-speed gear meshing but also absorbs operating heat. Combined with the automatic temperature control circulation system of the cooling and lubrication system, when the lubricating oil temperature reaches a preset value, automatic cooling and circulation replenishment are achieved through structures such as metal plugs and cooling frames, ensuring gear meshing accuracy and operating efficiency. The drill bit motor's synchronously driven heat dissipation component achieves both motor cooling and dust removal through high-speed blade rotation, preventing dust from adhering to the lead screw surface and affecting smooth operation. Simultaneously, the dust cover design effectively isolates impurities from intrusion. Furthermore, the combined design of a pneumatic slip ring and a sealing control valve ensures sealing during the dynamic liquid nitrogen transport process, preventing leakage and equipment damage. Combined with the strengthening effect of liquid nitrogen cryogenic treatment on the drill bit, the service life of vulnerable components is significantly extended.

[0017] 3. This invention allows for input of commands via the control panel to achieve functions such as motor start / stop, motion parameter adjustment, and liquid nitrogen flow control, without the need for complex manual intervention. The dual-axis linkage design in the horizontal and vertical directions, combined with the flexible combination of multiple loading blocks, can adapt to the fixing and loading requirements of rock samples of different sizes. It can realize tests under standard working conditions and can also simulate tunnel excavation scenarios under different depths and stress conditions through parameter adjustment, demonstrating extremely strong flexibility and adaptability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0019] Figure 1 This is a schematic diagram of the external structure of the CNC dual-axis linkage test apparatus for simulating square tunnel excavation and unloading according to an embodiment of the present invention. Figure 2 This is a partial front view schematic diagram of the internal structure of the CNC dual-axis linkage test device for simulating square tunnel excavation and unloading according to an embodiment of the present invention. Figure 3 This is a top view of a partial structural diagram of a CNC dual-axis linkage test device for simulating square tunnel excavation and unloading according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the cooling and lubrication system of the numerical control dual-axis linkage test device for simulating square tunnel excavation and unloading according to an embodiment of the present invention. Figure 5 This is a side view schematic diagram of the square hole drill bit and gear distribution structure of the CNC dual-axis linkage test device for simulating square tunnel excavation and unloading according to an embodiment of the present invention. Figure 6This is a schematic diagram of the cooling injection holes, pipes, and cavity distribution structure of a numerically controlled biaxial linkage test device for simulating square tunnel excavation and unloading according to an embodiment of the present invention. Figure 7 This is a schematic diagram of the pneumatic slip ring and sealing control valve distribution structure of a numerically controlled biaxial linkage test device for simulating square tunnel excavation and unloading according to an embodiment of the present invention. Figure 8 This is a schematic diagram of the internal structure of the drill rod of the CNC dual-axis linkage test device for simulating square tunnel excavation and unloading according to an embodiment of the present invention. Figure 9 for Figure 4 Enlarged structural diagram at point A in the middle; Figure 10 This is a schematic diagram of the metal blocking column control structure of the numerical control dual-axis linkage test device for simulating square tunnel excavation and unloading according to an embodiment of the present invention; Figure 11 This is a schematic diagram of the two-dimensional stress condition structure of the specimen of the numerically controlled biaxial linkage test device for simulating the excavation and unloading of a square tunnel according to an embodiment of the present invention.

[0020] Figure 12 This is a schematic diagram of the assembly of a CNC biaxial linkage test device for simulating square tunnel excavation and unloading on a true triaxial rock testing machine, as an embodiment of the invention.

[0021] In the diagram: 1. Square hole drill bit; 2. Drill rod; 3. Gear; 4. Shaft support; 5. Cooling injection hole; 6. Pipeline; 7. Cavity; 8. Pneumatic slip ring; 9. Sealing control valve; 10. Drill bit motor base; 11. Drill bit motor; 12. Vertical lead screw motor; 13. Coupling; 14. Lead screw; 15. Support plate; 16. Lead screw nut; 17. Lead screw support; 18. Horizontal lead screw nut; 19. Horizontal lead screw motor; 20. Horizontal lead screw; 21. Base plate; 22. Sample; 23. Control panel; 24. Vertical lower loading block; 25. Vertical left loading block; 26. Horizontal rear loading block; 27. Horizontal right loading block. 28. Side loading block; 29. ​​Horizontal upper side loading block; 30. Vertical lead screw motor controller; 31. Drill bit motor controller; 32. Horizontal lead screw motor controller; 33. Lubrication frame; 34. Internal frame; 35. Cooling and heat dissipation lubrication system; 36. Oil pump; 37. Conduit; 38. Cooling frame; 39. Liquid level sensor; 30. Temperature sensor; 31. Control component; 32. Metal plug; 33. Connecting spring; 34. Fixing plate; 35. Heat dissipation component; 36. Connecting plate; 37. Blade; 38. Dust cover; 39. Drive shaft; 30. Mounting bracket. Detailed Implementation

[0022] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0026] like Figures 1-12 As shown, the CNC dual-axis linkage test device for simulating square tunnel excavation and unloading provided by the present invention includes a square drill bit motor base 10, a drill bit motor 11 is provided at the upper end of the drill bit motor base 10, and a drill rod 2 and a drive shaft 37 are installed at the output end of the drill bit motor 11. A sealing control valve 9 is provided at the front end of the drill bit motor 11, and a drill rod 2 is installed at the center of the sealing control valve 9. A shaft support 4 is provided on the outside of the drill rod 2. Two sets of drill rods 2 are provided, and gears 3 are installed on the outside of both sets of drill rods 2. A square hole drill bit 1 is installed at the end of one set of gears 3, and two sets of gears 3 are provided, with the two sets of gears 3 meshing with each other.

[0027] A sample 22 is placed on one side of the square hole drill bit 1. The drill bit motor 11 starts and drives the drill rod 2 to rotate. The rotation of the drill rod 2 causes the gears 3 on the outside of the two drill rods 2 to mesh and rotate. The design of the shaft support 4 ensures the stability of the upper drill rod 2, thereby driving the drill rod 2 connected to the drill bit 1 to rotate, which in turn drives the drill bit 1 to make eccentric motion and rotate to cut the sample. The drill rod 2 and the sealing control valve 9 are connected by a pneumatic slip ring 8 to achieve a sealed connection during rotation, ensuring the sealing and stability of liquid nitrogen during dynamic transportation and preventing liquid nitrogen leakage. The cooling injection hole 5 is opened inside the drill rod 2, and a cavity 7 is provided at one end of the cooling injection hole 5. Liquid nitrogen is accurately injected into the cavity 7 through the pipe 6 and flows to the square hole drill bit 1 through the cooling injection hole 5. The sealing control valve 9 maintains the stability of the system. The pipe 6 is installed on the top of the cavity 7, and the pneumatic slip ring 8 is installed on the outside of the cavity 7.

[0028] It should be noted that the eccentric motion driven by the meshing of two gears is based on the Reuleaux triangle principle, which enables drilling of square holes.

[0029] A support plate 15 is installed at the bottom of the drill bit motor base 10, and a lead screw nut 16 is provided at the bottom of the support plate 15. Two sets of lead screws 14 are symmetrically arranged inside the lead screw nut 16, and a vertical lead screw motor 12 is installed at the top of the lead screw 14 through a coupling 13. A lead screw support 17 is installed at the bottom of the lead screw 14, and a horizontal lead screw nut 18 is provided at the bottom of the lead screw support 17. Two sets of horizontal lead screws 20 are symmetrically arranged inside the horizontal lead screw nut 18, and a horizontal lead screw motor 19 is installed at the end of the horizontal lead screw 20. A base plate 21 is installed at the bottom of the horizontal lead screw motor 19. The drill bit motor 11, the vertical lead screw motor 12, and the horizontal lead screw motor 19 are electrically connected to a control panel 23, and the control panel 23 is electrically connected to a vertical lead screw motor controller 29, a drill bit motor controller 30, and a horizontal lead screw motor controller 31. By controlling the controllers through the control panel 23 and inputting commands, the movement distance and cutting depth of the machine in the XZ direction can be precisely controlled.

[0030] The entire system is integrated and controlled by the control panel 23, which includes a vertical lead screw motor controller 29, a drill bit motor controller 30, and a horizontal lead screw motor controller 31. This enables precise and coordinated control of the drilling orientation, drilling depth, drill bit rotation speed, and liquid nitrogen flow rate. The vertical lead screw motor 12, the horizontal lead screw motor 19, and the drill bit motor 11 are linked to control the precise movement of the drill bit in the XZ plane, thus completing the excavation of a simulated square tunnel. Liquid nitrogen is continuously injected into the cooling injection hole 5 inside the drill rod 2, allowing the coolant to flow to the drill bit 2 and cool it down. This achieves synchronous cooling, effectively reducing thermal damage and surrounding rock disturbance, and realistically reproducing the stress redistribution characteristics during the unloading process of deep square tunnel excavation.

[0031] like Figures 3-9As shown, a mounting bracket 38 is provided at the upper end of the drill motor base 10, and a lubrication frame 32 is installed at the end of the mounting bracket 38. An inner frame 33 is provided on one side of the inner side of the lubrication frame 32, and two sets of drill rods 2 are installed inside the inner frame 33 through a lip seal ring. Lubricating oil is pre-installed inside the inner frame 33, and the two sets of meshing gears 3 are immersed in the lubricating oil. The design of the lubricating oil can lubricate and cool the gears 3, absorbing the heat generated by the gears 3 under high-speed meshing. In addition, the enclosed design of the lubrication frame 32 and the inner frame 33 can effectively avoid the possibility of powder generated during the cutting of the sample 22 adhering to the surface of the gears 3, and effectively avoid affecting the meshing accuracy of the gears 3.

[0032] Two sets of gears 3 are set inside the built-in frame 33. A control component 35 for controlling the flow is installed at the bottom of the built-in frame 33. The control component 35 includes a metal plug 3501, a connecting spring 3502 and a fixing plate 3503. A connecting spring 3502 is provided on one side of the metal plug 3501. A cooling and heat dissipation lubrication system 34 for auxiliary cooling is installed at the lower end of the metal plug 3501.

[0033] In some embodiments, the cooling and lubrication system 34 further includes an oil pump 3401 and a conduit 3402, and the bottom of the cooling frame 3403 is provided with a conduit 3402, and the end of the conduit 3402 is equipped with an oil pump 3401.

[0034] The cooling and lubrication system 34 also includes a cooling frame 3403, a liquid level sensor 3404 and a temperature sensor 3405. The liquid level sensor 3404 is installed inside the cooling frame 3403, and the temperature sensor 3405 is installed below the liquid level sensor 3404. A fixing plate 3503 is installed at the end of the connecting spring 3502.

[0035] When the lubricating oil in the built-in frame 33 absorbs heat to a preset value, the resistance of the thermistor increases and the current decreases, thereby reducing the magnetic force of the electromagnet. This allows the electromagnet to stop magnetically adsorbing the metal plug 3501. The metal plug 3501 is reset by the action of the connecting spring 3502, thus guiding the lubricating oil in the built-in frame 33 into the cooling frame 3403. When the lubricating oil rises to a preset height, the level sensor 3404 alarms. At the same time, when the temperature sensor 3405 in the cooling frame 3403 reaches a preset value, the oil pump 3401 can be started by the controller. Thus, the cooled lubricating oil can be replenished into the built-in frame 33 through the design of the conduit 3402 to continue cooling and heat dissipating the meshing gear 3.

[0036] like Figure 1 and Figure 3 As shown, a heat dissipation assembly 36 for auxiliary heat dissipation is provided at the end of the drive shaft 37.

[0037] In some embodiments, the heat dissipation assembly 36 includes a connecting plate 3601, blades 3602, and a dust cover 3603. The blades 3602 are distributed in a ring on the surface of the connecting plate 3601, and a dust cover 3603 is provided on the outside of the connecting plate 3601 and the blades 3602. The dust cover 3603 has a hollow structure and a circular cross-section. When the drill motor 11 is started, the square hole drill bit 1 is rotated to cut into the sample 22. At the same time, the drive shaft 37 and the connecting plate 3601 and the blades 3602 connected to the drive shaft 37 move accordingly. Through the high-speed rotation of the blades 3602, the design of the blades 3602 ensures that the air is blown towards one end of the drill rod 2. This is used to dissipate heat from the drill motor 11 and blow the dust generated during drilling and cutting away from the working area. This ensures that the dust is dispersed, heat is dissipated, and drilling and cutting are carried out accordingly, and avoids the dust acting on the surface of the horizontal lead screw 20, which would affect the smoothness of the lateral movement.

[0038] The test method of the CNC biaxial linkage test device for simulating the excavation and unloading of a square tunnel, provided in this embodiment of the invention, includes the following steps: Step 1: Install the CNC dual-axis linkage test device for simulating square tunnel excavation and unloading on the X-direction of the YD-SZ5000 deep multi-field coupled rock true triaxial excavation unloading-dynamic disturbance test system. The vertical direction is the Z-direction of the test machine, and the horizontal direction is the X and Y directions of the test machine. Fix the device base plate 21 on the test system. By inputting commands on the control panel 23, turn on the vertical screw motor controller 29 and the horizontal screw motor controller 31, and start the horizontal screw motor and the vertical screw motor 12. Through the coordinated movement of the horizontal screw and the vertical screw, adjust the position of the drill bit motor seat 10 so that the drill bit is placed at the position of square tunnel excavation, so that the drill bit is accurately aligned with the predetermined opening position of the sample. Step 2: Fix the rock sample 22. Place the rock sample 22 in the loading chamber of the testing machine, which consists of a vertical upper loading block, a vertical lower loading block, a horizontal left loading block, and a horizontal right loading block. Apply a small force in the vertical and horizontal directions to fix the rock sample 22 through the control system of the testing machine. The forces in the horizontal and vertical directions are equal. Step 3: Apply two-dimensional loading to rock specimen 22. After the rock specimen 22 is fixed on the testing machine, apply vertical stress at the same loading rate. σ v and horizontal stress σ h The two-dimensional stress level applied to a set depth can simulate stress environments at different depths, and different stresses can be recorded through a monitoring system and a data acquisition system. Step 4: Start the drill motor 11 to drive the square hole drill bit 1 to rotate and cut into the sample 22. Open the sealing control valve 9 and inject liquid nitrogen into the cooling injection hole 5 through the pipe 6. The liquid nitrogen is then evenly introduced into the drill rod through the cavity 7 to cool the drill bit 1. The drill rod 2 is equipped with a spiral channel to discharge the rock debris generated during the excavation of the square tunnel. When the drilling depth reaches the set position, turn off the liquid nitrogen injection switch and control the drill motor 11 to move in the opposite direction through the horizontal screw motor controller 31, so that the square hole drill bit 1 leaves the sample surface, completing the excavation and unloading simulation of the square tunnel. Then, turn off all motors. Step 5: Lubricating oil is pre-installed inside the built-in frame 33. The gear 3 is immersed in the lubricating oil, which can absorb the heat generated when the two sets of gears 3 mesh, and lubricate at the same time. When the lubricating oil in the built-in frame 33 absorbs heat to the preset value, the resistance of the thermistor increases and the current decreases, thereby reducing the magnetic force of the electromagnet. The electromagnet can then stop the magnetic attraction of the metal plug 3501. The metal plug 3501 is reset by the action of the connecting spring 3502, so that the lubricating oil in the built-in frame 33 is introduced into the cooling frame 3403. When the lubricating oil rises to the preset height, the liquid level sensor 3404 alarms. At the same time, when the temperature sensor 3405 in the cooling frame 3403 reaches the preset value, the oil pump 3401 can be started by the controller. Thus, the cooled lubricating oil can be replenished into the built-in frame 33 through the design of the conduit 3402 to continue to cool and dissipate heat from the meshing gears 3. Step six: When the drill motor 11 is started, the square hole drill bit 1 is rotated and cuts into the sample 22. At the same time, the drive shaft 37, the connecting plate 3601 and the blade 3602 connected to the drive shaft 37 move accordingly. Through the high-speed rotation of the blade 3602, the design of the blade 3602 ensures that the air blows towards one end of the drill rod 2. This is used to dissipate heat from the drill motor 11 and blow the dust generated during drilling and cutting away from the working area. This ensures that the dust is dispersed, heat is dissipated, and drilling and cutting are carried out accordingly, and avoids the dust acting on the surface of the horizontal lead screw 20, which would affect the smoothness of the lateral movement. Step 7: Continue loading the rock samples from the excavated square tunnel, and use a miniature camera to observe and record the failure process and characteristics of the surrounding rock in the square tunnel. Combine the stress and displacement data during the failure process to evaluate the deformation characteristics and failure mechanism of the surrounding rock after excavation and unloading of the square tunnel, and provide experimental basis for the stability design of underground engineering.

[0039] In summary, as Figures 1-12As shown, the CNC dual-axis linkage test device and method for simulating square tunnel excavation and unloading are used by installing the CNC dual-axis linkage test device for simulating square tunnel excavation and unloading on the X-direction of the YD-SZ5000 deep multi-field coupled rock true triaxial excavation unloading-dynamic disturbance test system. The vertical direction is the Z-direction of the test machine, and the horizontal direction is the X and Y directions of the test machine. The device base plate 21 is fixed on the test system. By inputting commands on the control panel 23, the vertical screw motor controller 29 and the horizontal screw motor controller 31 are turned on, and the horizontal screw motor 19 and the vertical screw motor 12 are started. The horizontal screw motor and the vertical screw motor are connected to the vertical screw motor. The coordinated movement of the straight screw adjusts the position of the drill bit motor seat 10, positioning the drill bit at the location of the square tunnel excavation, thus achieving precise alignment of the drill bit with the predetermined opening position of the sample. The rock sample 22 is fixed by placing it in the loading chamber of the testing machine, which consists of a vertical upper loading block, a vertical lower loading block, a horizontal left loading block, and a horizontal right loading block. The control system of the testing machine applies a small force in both the vertical and horizontal directions to fix the rock sample 22, with the forces in the horizontal and vertical directions being equal. Two-dimensional loading is then applied to the rock sample 22. After the rock sample 22 is fixed on the testing machine, the stress in the vertical direction is simultaneously applied at the same loading rate. σ v and horizontal stress σ hThe two-dimensional stress level applied to a set depth can simulate stress environments at different depths. Simultaneously, a monitoring system and data acquisition system record different stresses. The drill motor 11 is started, driving the square-hole drill bit 1 to rotate and cut into the sample 22. The sealing control valve 9 is opened, and liquid nitrogen is injected through the pipe 6 into the cooling injection hole 5. It is then evenly introduced into the drill rod through the cavity 7 to cool the drill bit 1. The drill rod 2 is equipped with a spiral channel to discharge rock debris generated during the excavation of the square tunnel. When the drilling depth reaches the set position, the liquid nitrogen injection switch is closed, and the drill motor 11 is controlled to reverse its movement via the horizontal screw motor controller 31. The square hole drill bit 1 is removed from the sample surface to complete the excavation and unloading simulation of the square tunnel, and all motors are shut down. Lubricating oil is pre-installed inside the inner frame 33, and gears 3 are immersed in the lubricating oil. This allows for heat absorption and lubrication simultaneously, addressing the heat generated when the two sets of gears 3 mesh. When the lubricating oil in the inner frame 33 absorbs heat to a preset value, the resistance of the thermistor increases, the current decreases, and thus the magnetic force of the electromagnet decreases. This allows the electromagnet to stop magnetically adsorbing the metal plug 3501. The metal plug 3501 is reset by the connecting spring 3502, allowing the lubricating oil in the inner frame 33 to be introduced into the cooling frame 3403. In the process, when the lubricating oil rises to a preset height, the level sensor 3404 alarms. Simultaneously, when the temperature sensor 3405 in the cooling frame 3403 reaches a preset value, the controller can start the oil pump 3401. This allows the cooled lubricating oil to be replenished into the inner frame 33 through the conduit 3402, continuing to cool and dissipate heat from the meshing gears 3. Simultaneously, when the drill motor 11 is started, driving the square hole drill bit 1 to rotate and cut into the sample 22, the drive shaft 37, the connecting disc 3601 connected to the drive shaft 37, and the blades 3602 move accordingly. Through the high-speed rotation of the blades 3602, the lubricating oil is cooled and dissipated. The design of 02 ensures that the airflow blows towards one end of the drill rod 2, which is used to dissipate heat from the drill motor 11 and to blow the dust generated during drilling and cutting away from the working area. This ensures that the dust is dispersed, heat is dissipated, and drilling and cutting proceed smoothly, preventing dust from acting on the surface of the horizontal lead screw 20 and affecting the smoothness of lateral movement. The rock samples of the excavated square tunnel are further loaded, and a miniature camera is used to observe and record the failure process and characteristics of the surrounding rock of the square tunnel. Combined with the stress and displacement data during the failure process of the surrounding rock, the deformation characteristics and failure mechanism of the surrounding rock of the square tunnel under excavation and unloading are evaluated, providing experimental basis for the stability design of underground engineering.

[0040] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A numerically controlled biaxial linkage test device for simulating the excavation and unloading of a square tunnel, comprising a cooling injection hole (5), a sealing control valve (9), and a drill bit motor base (10), characterized in that: The upper end of the drill bit motor base (10) is provided with a drill bit motor (11), and the output end of the drill bit motor (11) is equipped with a drill rod (2) and a drive shaft (37). The sealing control valve (9) is located at the front end of the drill bit motor (11). The center of the sealing control valve (9) is equipped with a drill rod (2), and the outside of the drill rod (2) is provided with a shaft support (4). The drill rod (2) is provided in two sets, and gears (3) are installed on the outside of both sets of drill rods (2). One set of gears (3) 3) is equipped with a square hole drill bit (1) at its end, and two sets of gears (3) are provided, which mesh with each other. A sample (22) is provided on one side of the square hole drill bit (1). The cooling injection hole (5) is opened inside the drill rod (2), and a cavity (7) is provided at one end of the cooling injection hole (5). A pipe (6) is installed on the top of the cavity (7), and a pneumatic slip ring (8) is installed on the outside of the cavity (7). The bottom of the drill bit motor base (10) is equipped with A support plate (15) is provided, and a lead screw nut (16) is provided at the bottom of the support plate (15). Two sets of lead screws (14) are symmetrically arranged inside the lead screw nut (16). A vertical lead screw motor (12) is installed at the top of the lead screw (14) through a coupling (13). A lead screw support (17) is installed at the bottom of the lead screw (14), and a horizontal lead screw nut (18) is provided at the bottom of the lead screw support (17). Two sets of lead screws (14) are symmetrically arranged inside the horizontal lead screw nut (18). A horizontal lead screw (20) is assembled, and a horizontal lead screw motor (19) is installed at the end of the horizontal lead screw (20). A base plate (21) is installed at the bottom of the horizontal lead screw motor (19). The drill bit motor (11), the vertical lead screw motor (12), and the horizontal lead screw motor (19) are electrically connected to a control panel (23). The control panel (23) is internally electrically connected to a vertical lead screw motor controller (29), a drill bit motor controller (30), and a horizontal lead screw motor controller (31).

2. The CNC biaxial linkage test device for simulating square tunnel excavation and unloading according to claim 1, characterized in that: The upper end of the drill motor base (10) is provided with a mounting bracket (38), and a lubrication frame (32) is installed at the end of the mounting bracket (38).

3. The CNC biaxial linkage test device for simulating square tunnel excavation and unloading according to claim 2, characterized in that: The lubrication frame (32) has an inner frame (33) on one side, and two sets of drill rods (2) are installed inside the inner frame (33) through a lip seal ring.

4. The CNC biaxial linkage test device for simulating square tunnel excavation and unloading according to claim 3, characterized in that: The two sets of gears (3) are disposed inside the built-in frame (33), and a control component (35) for controlling the flow is installed at the bottom of the built-in frame (33).

5. The CNC biaxial linkage test device for simulating square tunnel excavation and unloading according to claim 4, characterized in that: The control component (35) includes a metal plug (3501), a connecting spring (3502) and a fixing plate (3503), and a connecting spring (3502) is provided on one side of the metal plug (3501), and a fixing plate (3503) is installed at the end of the connecting spring (3502).

6. The CNC biaxial linkage test device for simulating square tunnel excavation and unloading according to claim 5, characterized in that: The end of the drive shaft (37) is provided with a heat dissipation component (36) for auxiliary heat dissipation, and the heat dissipation component (36) includes a connecting plate (3601), blades (3602) and a dust cover (3603). The surface of the connecting plate (3601) is circumferentially distributed with blades (3602), and the connecting plate (3601) and the blades (3602) are provided with a dust cover (3603) on their exterior.

7. The CNC biaxial linkage test device for simulating square tunnel excavation and unloading according to claim 6, characterized in that: The dust cover (3603) has a hollow structure and a circular cross-section.

8. The CNC biaxial linkage test device for simulating square tunnel excavation and unloading according to claim 7, characterized in that: The lower end of the metal plug (3501) is equipped with a cooling and heat dissipation lubrication system (34) for auxiliary cooling. The cooling and heat dissipation lubrication system (34) includes a cooling frame (3403), a liquid level sensor (3404) and a temperature sensor (3405). The liquid level sensor (3404) is installed inside the cooling frame (3403), and the temperature sensor (3405) is installed below the liquid level sensor (3404).

9. The CNC biaxial linkage test device for simulating square tunnel excavation and unloading according to claim 8, characterized in that: The cooling and lubrication system (34) further includes an oil pump (3401) and a conduit (3402), and the bottom of the cooling frame (3403) is provided with a conduit (3402), and the end of the conduit (3402) is equipped with an oil pump (3401).

10. A numerically controlled biaxial linkage test method for simulating the excavation and unloading of a square tunnel, applied to the numerically controlled biaxial linkage test device for simulating the excavation and unloading of a square tunnel as described in claim 8, characterized in that: The test method for this numerically controlled biaxial linkage test device for simulating the excavation and unloading of a square tunnel includes the following steps. Step 1: Install the CNC dual-axis linkage test device for simulating square tunnel excavation and unloading in the X direction of the YD-SZ5000 deep multi-field coupled rock true triaxial excavation unloading-dynamic disturbance test system. The vertical direction is the Z direction of the test machine, and the horizontal direction is the X and Y directions of the test machine. Fix the device base plate (21) on the test system. By inputting the command on the control panel (23), turn on the vertical screw motor controller (29) and the horizontal screw motor controller (31), start the horizontal screw motor and the vertical screw motor, and adjust the position of the drill bit motor seat (10) by moving the horizontal screw and the vertical screw, so that the drill bit is placed in the square tunnel excavation position, and the drill bit is accurately aligned with the predetermined opening position of the sample. Step 2: Fix the rock sample (22). Place the rock sample (22) in the loading chamber of the testing machine, which consists of a vertical upper loading block, a vertical lower loading block, a horizontal left loading block, and a horizontal right loading block. Apply a small force in the vertical and horizontal directions to fix the rock sample (22) through the control system of the testing machine. The forces in the horizontal and vertical directions are equal. Step 3: Two-dimensional loading is applied to the rock sample (22). After the rock sample (22) is fixed on the testing machine, the stress σv in the vertical direction and the stress σh in the horizontal direction are simultaneously loaded at the same loading rate to the two-dimensional stress level at the set depth. This can simulate the stress environment at different depths. At the same time, different stresses are recorded through the monitoring system and data acquisition system. Step 4: Start the drill motor (11) to drive the square hole drill bit (1) to rotate and cut into the sample (22). Open the sealing control valve (9) and inject liquid nitrogen into the cooling injection hole (5) through the pipe (6). The liquid nitrogen is evenly introduced into the drill rod through the cavity (7) to cool the drill bit (1). The drill rod (2) is equipped with a spiral channel to discharge the rock debris generated during the excavation of the square tunnel. When the drilling depth reaches the set position, close the liquid nitrogen injection switch and control the drill motor (11) to move in the opposite direction through the horizontal screw motor controller (31) so that the square hole drill bit (1) leaves the sample surface, completing the excavation and unloading simulation of the square tunnel. Then, turn off all motors. Step 5: Lubricating oil is pre-set inside the built-in frame (33). The gear (3) is immersed in the lubricating oil, which can absorb the heat generated when the two sets of gears (3) mesh and lubricate at the same time. When the lubricating oil in the built-in frame (33) absorbs heat to the preset value, the resistance of the thermistor increases and the current decreases, thereby reducing the magnetic force of the electromagnet. Then, the electromagnet can stop the magnetic adsorption of the metal plug (3501). The metal plug (3501) will be reset due to the action of the connecting spring (3502). The lubricating oil in the built-in frame (33) will be introduced into the cooling frame (3403). When the lubricating oil rises to the preset height, the liquid level sensor (3404) alarms. At the same time, when the temperature sensor (3405) in the cooling frame (3403) reaches the preset value, the oil pump (3401) can be started by the controller. The lubricating oil after cooling can be replenished into the built-in frame (33) again through the design of the conduit (3402) to cool and dissipate heat from the meshing gears (3). Step six: When the drill motor (11) is started and the square hole drill bit (1) is rotated to cut into the sample (22), the drive shaft (37) and the connecting plate (3601) and blade (3602) connected to the drive shaft (37) move accordingly. Through the high-speed rotation of the blade (3602), the drill motor (11) is cooled while the dust generated during drilling is blown away from the working area. Step 7: Continue loading the rock samples from the excavated square tunnel, and use a miniature camera to observe and record the failure process and characteristics of the surrounding rock in the square tunnel. Combine the stress and displacement data during the failure process to evaluate the deformation characteristics and failure mechanism of the surrounding rock after excavation and unloading in the square tunnel.

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