Ultrasonic focusing type deep rock breaking auxiliary device and dynamic excitation method thereof

Abstract

The invention discloses an ultrasonic focusing type deep rock breaking auxiliary device and a dynamic excitation method thereof. The device comprises a fastening propelling device, a rock inherent frequency detection system and an ultrasonic focusing excitation system which are arranged outside a drilling machine in a sleeving manner. Wherein the ultrasonic focusing excitation system is used for converging ultrasonic energy into a rock mass in front of a drill bit through a plurality of focusing acoustic lenses which are annularly arranged and can independently rotate. During working, the inherent frequency of a rock mass is detected firstly, ultrasonic waves with the corresponding frequency are generated, then the refraction angle of the ultrasonic waves is adjusted by dynamically rotating the focusing acoustic lens, a focusing point is made to move forwards synchronously along with increase of the drilling depth, and continuous and accurate presplitting of deep rock in front of a drill rod is achieved. The rock strength can be effectively reduced, the rock breaking efficiency is improved, meanwhile, the hole wall completeness is protected, and drilling tool damage is reduced.

Description

Technical Field

[0001] This invention pertains to rock drilling tools in the field of tunnel excavation, specifically involving an ultrasonic focusing deep rock breaking auxiliary device and its dynamic excitation method. Background Technology

[0002] Traditional rock drilling machines suffer from slow construction speed and high drill bit wear, which hinders the improvement of tunneling efficiency in rock tunnels. The natural frequency of intact and dense rock is generally greater than 20 kHz. When the applied ultrasonic excitation frequency is close to the natural frequency of the rock, resonance will occur, causing internal cracks to develop rapidly, reducing strength and making the rock more prone to breakage.

[0003] Existing ultrasonic drilling rigs typically mount the ultrasonic transducer, amplitude transformer, drill rod, and drill bit on the same axis. The high-frequency vibrations generated by ultrasonic excitation are concentrated on the drill bit, causing fatigue damage to the rock surface due to high-frequency impact, resulting in reduced strength and increased fracturing. However, this method suffers from limited effective ultrasonic excitation within the rock, poor fissure development, and low energy utilization due to frictional heat loss from high-frequency vibration of the drill rod. Separating the ultrasonic excitation device from the drill rod and applying ultrasonic excitation to the rock surface also results in limited ultrasonic excitation depth and the development of rock fissures in the borehole wall, making it difficult to meet the requirements for high-quality and high-efficiency drilling.

[0004] When sound waves pass through the interface of media with different sound speeds, they will be refracted. Based on this characteristic, an acoustic lens can change the direction of sound wave transmission, while a focusing acoustic lens can converge sound waves into a point. The shapes of focusing acoustic lenses are generally plano-concave and zone plates. Summary of the Invention

[0005] The purpose of this invention is to provide an ultrasonic focusing deep rock breaking auxiliary device and its dynamic excitation method. The ultrasonic excitation device is separated from the drill pipe, and the ultrasonic excitation device is designed based on the working principle of acoustic lens. This can realize the focused excitation of ultrasonic waves on deep rocks, significantly improving drilling efficiency.

[0006] This invention provides an ultrasonic focusing deep rock breaking auxiliary device, including a fastening propulsion device, a rock mass natural frequency zone detection system, and an ultrasonic focusing excitation system; The fastening and propulsion device includes a fastening device and a hydraulic propulsion device. The fastening device is cylindrical and is fitted around the outside of the drilling rig. The drill rod passes through the middle of the fastening device. The hydraulic propulsion device includes an annular hydraulic cylinder, a piston that cooperates with the hydraulic cylinder, and an annular steel ring fixed to the front section of the piston; the hydraulic cylinder is mounted on the fastening device. The rock mass natural frequency zoning detection system includes a connector, an amplitude data transmission line, an amplitude data collection system, a detection frequency output line, and a natural frequency analyzer. The ultrasonic focusing excitation system includes an ultrasonic generator, a high-frequency current input line, a circuit control system, a power supply line, N sets of bases, a focusing acoustic lens, an amplitude transformer, a piezoelectric accelerometer, and an ultrasonic transducer. The connector is ring-shaped and mounted on the annular steel ring; the base is evenly distributed in a ring and fixed on the front end face of the connector, and the front end of the base is provided with a mounting groove. The bottom end of the amplitude transformer is installed in the mounting groove, and the focusing acoustic lens is hinged to the top end of the amplitude transformer via a rotating shaft, so that the focusing acoustic lens can rotate toward the axis of the connector; the ultrasonic transducer and the piezoelectric accelerometer are installed at the bottom of the mounting groove. The piezoelectric accelerometer is collected by the amplitude data transmission line and sent to the amplitude data collection system, and then transmitted to the natural frequency analyzer by the detection frequency output line. The ultrasonic generator has an adjustable frequency. Different ultrasonic electrical signals are input to the circuit control system through the high-frequency current input line. The circuit control system then inputs the different ultrasonic electrical signals to the N ultrasonic transducers through the power supply line.

[0007] Furthermore, a buffer isolation layer is provided on the inner wall of the mounting groove to reduce the vibration impact of the amplitude rod on the base and prevent the amplitude rods from affecting each other.

[0008] Preferably, the buffer isolation layer adopts a honeycomb metal structure.

[0009] Preferably, the hydraulic propulsion device further includes a pressure sensor and a hydraulic control system. The pressure sensor is used to detect the force state of the piston, and the hydraulic control system controls the oil pressure of the hydraulic propulsion device to ensure that the focusing acoustic lens can always be in close contact with the rock surface with a certain pressure, while not interfering with the drilling rig's forward drilling.

[0010] Preferably, the amplitude data transmission line and amplitude data collection system are located inside or on the surface of the connector.

[0011] Preferably, the focusing acoustic lens is elliptical cylindrical, with the apex of the ellipse in close contact with the rock.

[0012] The auxiliary drilling device is cylindrical and is mounted on the drilling rig using a fastening device. The fastening device is sleeve-shaped, with its interior fitting the exterior of the drilling rig and being fitted onto the outside of the drilling rig. It is secured by clamps. The hydraulic propulsion device can apply thrust in the drilling direction to ensure that the focusing acoustic lens is in close contact with the surface of the rock being drilled. The hydraulic propulsion device adjusts the length of the piston rod as the drilling depth of the drill rod changes.

[0013] The drilling rig applies impact vibration to the rock through the drill rod. The focusing acoustic lens senses and receives the rock vibration and transmits the rock vibration signal to the piezoelectric accelerometer through the amplitude transformer. The signal is converted into an electrical signal. Each piezoelectric accelerometer collects the signal through the amplitude data transmission line to the amplitude data collection system. Then, the amplitude detection result of the rock is output to the natural frequency analyzer through the detection frequency output line to determine the average natural frequency of the rock. The detection result is input to the frequency-adjustable ultrasonic generator.

[0014] The frequency-adjustable ultrasonic generator produces a high-frequency alternating current, which is input into multiple ultrasonic transducers arranged in a ring through a circuit control system. The electrical signal is converted into a vibration signal and concentrated onto the focusing acoustic lens at the top through an amplitude transformer.

[0015] The ultrasonic waves generated by the ultrasonic transducer are transmitted to the deep rock at a certain refraction angle by changing the transmission path through a focusing acoustic lens. The ultrasonic vibrations generated by multiple ultrasonic transducers arranged in a ring are focused on the rock in front of the borehole, and the excitation vibrations perpendicular to the borehole direction cancel each other out. The focusing acoustic lens is elliptical cylindrical, and the elliptical surface can make close contact with the rock. As the borehole depth increases, the focusing acoustic lens shaft is rotated, and the refraction angle of the ultrasonic waves is changed by changing the transmission path length of the ultrasonic waves in the focusing acoustic lens, thereby adjusting the position of the ultrasonic focusing excitation point and realizing dynamic excitation of the rock in front of the drill pipe.

[0016] The present invention provides an ultrasonic focusing-assisted dynamic excitation method for deep rock breaking, comprising the following steps: 1. Fix the drilling rig to the construction area using the support structure. Fit the fastening device around the outside of the drilling rig. Pass the drill rod through the middle of the fastening device. Fix the auxiliary drilling device to the drilling rig. Rotate the focusing acoustic lens toward the borehole so that the initial excitation position of the ultrasonic wave is the rock surface. The hydraulic propulsion device injects fluid, the piston extends, and the focusing acoustic lens is pressed tightly against the rock surface with a certain pressure. Place the natural frequency analyzer and the adjustable frequency ultrasonic generator on the ground and connect the high-frequency current input line and the detection frequency output line. 2. Start the drilling rig. The drill rod applies a rotating impact to the rock mass. The rock mass natural frequency detection system receives and determines the natural frequency of the rock mass. The frequency-adjustable ultrasonic generator generates a corresponding high-frequency current based on the detection results. The ultrasonic transducer converts the high-frequency current into high-frequency mechanical vibration and excites the working rock through the amplitude transformer and focusing acoustic lens. Third, during drilling operations, the hydraulic propulsion device automatically retracts the piston rod according to the drilling depth, adjusting the length of the auxiliary drilling device; the rock position at the top of the drill rod is set as the predetermined focus, ensuring that the focusing acoustic lens is always in close contact with the rock surface. At the same time, the focusing acoustic lens also rotates outward according to the drilling depth, causing the ultrasonic waves from N units to converge at the predetermined focus in the rock mass in front of the drill rod, providing deep and high-precision dynamic excitation to the rock in front of the drill rod, reducing the rock strength, and achieving efficient drilling of the rock; as the borehole gradually deepens, it continues to rotate outward to adjust the angle of the focusing acoustic lens, moving the predetermined focus forward, and continuing drilling; 4. After the rock drilling is completed, rotate the drilling rig in the opposite direction to withdraw one drill rod, remove the drill rod, retract the piston on the hydraulic propulsion device, shut down the auxiliary drilling device, disconnect the high-frequency current input line and the detection frequency output line, loosen the clamps of the fastening device, remove the auxiliary drilling device from the drilling rig, then connect the drilling rig and the drill rod in the hole, withdraw the drill rod normally, and finally shut down the drilling rig and tidy up the construction area.

[0017] Furthermore, the rotation angle of the focusing acoustic lens remains consistent.

[0018] The present invention has the following beneficial effects: 1. The ultrasonic excitation device and the drill pipe are separated, and the ultrasonic zone excitation and drilling rock breaking are performed separately. While ensuring the rock excitation effect, the heat energy generated by the high frequency vibration of the drill pipe is significantly reduced, avoiding the excitation damage of the drill pipe by the ultrasonic waves, and reducing energy and drill bit loss. 2. The present invention uses a focusing acoustic lens to focus ultrasonic waves. Compared with ultrasonic excitation devices that do not use a focusing acoustic lens, the ultrasonic focusing excitation energy level at the same location inside the rock is higher, which can effectively excite the rock at a greater depth. Moreover, the excitation energy level can be increased by increasing the number of transducers. 3. The ultrasonic generator of the present invention is arranged in a ring. At the ultrasonic focusing excitation point, the excitation vibrations perpendicular to the drilling direction cancel each other out. The rock at this point is only subjected to the excitation vibration along the drilling direction. At the same time, the ultrasonic excitation energy level generated by a single ultrasonic generator is small, making it difficult to effectively excite the deep rock area other than the focusing point. Therefore, high-precision excitation of the rock at the front end of the borehole can be achieved, and the integrity of the rock in the borehole wall can be guaranteed. 4. The auxiliary drilling device can be directly installed on the drilling rig, making it convenient to use. Attached Figure Description

[0019] Figure 1 This is a plan view of the ultrasonic focusing excitation auxiliary drilling device for deep rocks according to the present invention; Figure 2 This is a three-dimensional schematic diagram of the ultrasonic focusing excitation auxiliary drilling device for deep rocks according to the present invention; Figure 3 This is a schematic diagram of the ultrasonic focusing excitation device of the present invention; Figure 4 This is a schematic diagram of the ultrasonic dynamic focusing excitation process I of the present invention; Figure 5 This is a schematic diagram of the ultrasonic dynamic focusing excitation process II of the present invention.

[0020] In the diagram: 1—Drilling rig, 2—Fastening device, 3—Hydraulic propulsion device, 4—Connector, 5—Base, 6—Amplitude rod, 7—Drill rod, 8—Focusing acoustic lens, 9—Rock, 10—Detection frequency output line, 11—Natural frequency analyzer, 12—High-frequency current input line, 13—Ultrasonic generator, 14—Power supply line, 15—Circuit control system, 16—Amplitude data collection system, 17—Ultrasonic transducer, 18—Piezoelectric accelerometer, 19—Amplitude data transmission line, 20—Focusing acoustic lens shaft, 21—Drill hole, 22—Ultrasonic focusing excitation point. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings, but this does not limit the invention to the scope of the embodiments described. In the text, N refers to a natural number; in the accompanying drawings, N is 8; however, in actual implementations, N can be a natural number between 6 and 10.

[0022] Please see Figure 1 , Figure 2 , Figure 3 An ultrasonic focusing deep rock breaking auxiliary device includes a fastening propulsion device, a rock mass natural frequency zone detection system, and an ultrasonic focusing excitation system; The fastening and propulsion device includes a fastening device 2 and a hydraulic propulsion device 3. The fastening device 2 is cylindrical and is fitted onto the outside of the drilling rig 1. The drill rod 7 passes through the middle of the fastening device 2. The fastening device 2 is used to install equipment such as the hydraulic propulsion device 3, connector 4, and amplitude transformer 6 onto the drilling rig 1. The fastening device 2 can be fixed to the drilling rig 1 by means of flanges, bolts, or clamps.

[0023] The hydraulic propulsion device 3 includes an annular hydraulic cylinder, a piston that cooperates with the hydraulic cylinder, and an annular steel ring fixed to the front section of the piston. The hydraulic cylinder is mounted on the fastening device 2. Specifically, the hydraulic cylinder is an annular structure that cooperates with the fastening device 2, the piston is also annular, and the top of the annular steel ring is used to install the connector 4. This annular structure design is mainly to avoid affecting the operation of the drill pipe 7.

[0024] The rock mass natural frequency zoning detection system includes connector 4, amplitude data transmission line 19, amplitude data collection system 16, detection frequency output line 10, and natural frequency analyzer 11; The ultrasonic focusing excitation system includes an ultrasonic generator 13, a high-frequency current input line 12, a circuit control system 15, a power supply line 14, eight sets of bases 5, a focusing acoustic lens 8, an amplitude transformer 6, a piezoelectric accelerometer 18, and an ultrasonic transducer 17. Connector 4 is ring-shaped and mounted on a ring-shaped steel ring; base 5 is evenly distributed in a ring and fixed on the front end face of connector 4. The front end of base 5 is provided with a mounting groove. The bottom end of amplitude rod 6 is installed in the mounting groove. Focusing acoustic lens 8 is hinged to the top end of amplitude rod 6 through rotating shaft 20, so that focusing acoustic lens 8 can rotate toward the axis of connector 4; ultrasonic transducer 17 and piezoelectric accelerometer 18 are installed at the bottom of the mounting groove. That is, eight sets of bases 5, focusing acoustic lenses 8, amplitude transformers 6, piezoelectric accelerometers 18, and ultrasonic transducers 17 are evenly distributed along the annular end face of connector 4. Each set of bases 5, focusing acoustic lenses 8, amplitude transformers 6, piezoelectric accelerometers 18, and ultrasonic transducers 17 is independent of each other. Since different amplitude transformers 6 may transmit vibration frequencies differently, a buffer isolation layer is set on the inner wall of the mounting groove to reduce the vibration impact of the amplitude transformers 6 on the bases 5 in order to prevent mutual interference between the amplitude transformers 6. The buffer isolation layer adopts a honeycomb metal structure and has a certain strength.

[0025] In use, the eight focusing acoustic lenses 8 rotate at the same angle in the direction of the axis of the connector 4 and rotate synchronously, so that the ultrasonic waves can pass through the focusing acoustic lenses 8 and move forward in the direction they point. This causes the ultrasonic beams refracted by each lens to intersect at the same predetermined focal point in front of the borehole 21, thereby maximizing the ultrasonic energy at the predetermined focal point. The piezoelectric accelerometer 18 is collected by the amplitude data transmission line 19 and sent to the amplitude data collection system 16, and transmitted to the natural frequency analyzer 11 through the detection frequency output line 10. The ultrasonic generator 13 has an adjustable frequency. Different ultrasonic electrical signals are input to the circuit control system 15 through the high-frequency current input line 12. The circuit control system 15 then inputs the different ultrasonic electrical signals to the eight ultrasonic transducers 17 through the power supply line 14.

[0026] Preferably, the hydraulic propulsion device 3 also includes a pressure sensor and a hydraulic control system. The pressure sensor is used to detect the force state of the piston, and the hydraulic control system controls the oil pressure of the hydraulic propulsion device 3 to ensure that the focusing acoustic lens 8 can always be pressed tightly against the surface of the rock 9 with a certain pressure, while not interfering with the drilling rig 1 drilling forward.

[0027] In order to improve the ultrasonic focusing effect, preferably, the focusing acoustic lens 8 is elliptical cylindrical, and the curved surface of the tip of the ellipse is in close contact with the rock 9.

[0028] The number of N can be changed depending on different rock conditions, and N is a natural number between 6 and 10. In this embodiment, it is 8.

[0029] Preferably, the amplitude data transmission line 19 and the amplitude data collection system 16 are arranged inside or on the surface of the connector 4.

[0030] The auxiliary drilling device is cylindrical and is mounted on the drilling machine 1 by fastening device 2. Fastening device 2 is sleeve-shaped, with its interior fitting the exterior of the drilling machine 1 and being fitted onto the outside of the drilling machine 1. It is fastened by clamps. The hydraulic propulsion device 3 can apply thrust in the drilling direction to ensure that the focusing acoustic lens 8 is in close contact with the surface of the working rock 9. The hydraulic propulsion device 3 adjusts the length of the piston rod as the drilling depth of the drill rod 7 changes.

[0031] The drilling rig 1 applies impact vibration to the rock 9 through the drill rod 7. The focusing acoustic lens 8 senses and receives the rock vibration and transmits the rock vibration signal to the piezoelectric accelerometer 18 through the amplitude transformer 6, converting it into an electrical signal. Each piezoelectric accelerometer 18 collects the signal through the amplitude data transmission line 19 to the amplitude data collection system 16, and then outputs the amplitude detection result of the rock 9 to the natural frequency analyzer 11 through the detection frequency output line 10 to determine the average natural frequency of the rock 9. The detection result is then input to the frequency-adjustable ultrasonic generator 13.

[0032] The ultrasonic generator 13 generates a high-frequency alternating current, which is input into multiple ultrasonic transducers 17 arranged in a ring through the circuit control system 15. The electrical signal is converted into a vibration signal and concentrated onto the focusing acoustic lens 8 at the top through the amplitude transformer 6.

[0033] The ultrasonic waves generated by the ultrasonic transducer 17 are transmitted to the depth of the rock 9 by changing the transmission path through the focusing acoustic lens 8 and according to a certain refraction angle. The ultrasonic vibrations generated by the multiple ultrasonic transducers 17 arranged in a ring are focused on the rock in front of the borehole 21, and the excitation vibrations perpendicular to the drilling direction cancel each other out. The focusing acoustic lens 8 is elliptical cylindrical, and the elliptical surface can be in close contact with the rock 9. As the depth of the borehole 21 increases, the focusing acoustic lens shaft 20 is rotated to change the refraction angle of the ultrasonic waves by changing the transmission path length of the ultrasonic waves in the focusing acoustic lens 8, thereby adjusting the position of the ultrasonic focusing excitation point 22 and realizing dynamic excitation of the rock in front of the drill rod 7.

[0034] The present invention provides an ultrasonic focusing-assisted dynamic excitation method for deep rock breaking, comprising the following steps: 1. The drilling rig 1 is fixed to the construction area by the support structure. The fastening device 2 is fitted on the outside of the drilling rig 1. The drill rod 7 passes through the middle of the fastening device 2. The auxiliary drilling device is fixed on the drilling rig 1. The focusing acoustic lens 8 is rotated toward the drilling hole so that the initial excitation position of the ultrasonic wave is the surface of the rock 9. The hydraulic propulsion device 3 injects fluid, the piston extends, and the focusing acoustic lens 8 is pressed tightly against the surface of the rock mass with a certain pressure. The natural frequency analyzer 11 and the frequency-adjustable ultrasonic generator 13 are placed on the ground and connected to the high-frequency current input line 12 and the detection frequency output line 10. 2. Start the drilling rig 1, the drill rod 7 applies a rotating impact to the rock mass, the rock mass natural frequency detection system receives and determines the natural frequency of the rock mass, the adjustable ultrasonic generator 13 generates a corresponding high frequency current according to the detection result, the ultrasonic transducer 17 converts the high frequency current into high frequency mechanical vibration and excites the construction rock through the amplitude transformer 6 and the focusing acoustic lens 8. III. Figure 4 As shown, during the drilling process of drilling rig 1, the hydraulic propulsion device 3 automatically retracts the piston rod according to the drilling depth, adjusting the length of the auxiliary drilling device; the rock position at the top of drill rod 7 is set as the predetermined focal point, ensuring that the focusing acoustic lens 8 is always in close contact with the surface of rock 9. At the same time, the focusing acoustic lens 8 also rotates outward according to the drilling depth, causing the ultrasonic waves from N units to converge at the predetermined focal point in the rock body in front of drill rod 7, forming an ultrasonic focusing excitation point 22, which provides deep and high-precision dynamic excitation to the rock in front of drill rod 7, reducing the rock strength and achieving efficient drilling of the rock; as the drilling gradually deepens, as... Figure 5 As shown, continue to rotate outward to adjust the angle of the focusing acoustic lens 8, so that the predetermined focal point moves forward, and continue drilling; 4. After the rock drilling is completed, rotate the drilling rig 1 in the opposite direction to withdraw one drill rod, remove the drill rod, retract the piston on the hydraulic propulsion device 3, shut down the auxiliary drilling device, disconnect the high-frequency current input line 12 and the detection frequency output line 10, loosen the clamp of the fastening device 2, remove the auxiliary drilling device from the drilling rig 1, then connect the drilling rig 1 and the drill rod in the hole, withdraw the drill rod normally, and finally shut down the drilling rig and clean up the construction area.

[0035] Furthermore, the rotation angle of the focusing acoustic lens 8 remains consistent.

[0036] The present invention has the following beneficial effects: 1. The ultrasonic excitation device and drill pipe 7 are separated, and the ultrasonic zone excitation effect on the rock and the drilling rock breaking effect are performed separately. While ensuring the rock excitation effect, the heat energy generated by the high frequency vibration of drill pipe 7 is significantly reduced, avoiding the excitation damage of ultrasonic waves to drill pipe 7, and reducing energy and drill bit loss. 2. The present invention uses a focusing acoustic lens 8 to focus ultrasonic waves. Compared with an ultrasonic excitation device that does not use a focusing acoustic lens 8, the ultrasonic focusing excitation energy level at the same position inside the rock is higher, which can effectively excite the rock at a greater depth. Moreover, the excitation energy level can be increased by increasing the number of transducers. 3. The ultrasonic generator of the present invention is arranged in a ring. At the ultrasonic focusing excitation point, the excitation vibrations perpendicular to the drilling direction cancel each other out. The rock at this point is only subjected to the excitation vibration along the drilling direction. At the same time, the ultrasonic excitation energy level generated by a single ultrasonic generator is small, making it difficult to effectively excite the deep rock area other than the focusing point. Therefore, high-precision excitation of the rock at the front end of the borehole can be achieved, and the integrity of the rock in the borehole wall can be guaranteed. 4. The auxiliary drilling device can be directly installed on drilling rig 1, making it convenient to use.

Claims

1. An ultrasonic focusing deep rock-breaking auxiliary device, characterized in that, This includes a fastening propulsion device, a rock mass natural frequency zoning detection system, and an ultrasonic focusing excitation system; The fastening and propulsion device includes a fastening device (2) and a hydraulic propulsion device (3). The fastening device (2) is cylindrical and is fitted around the outside of the drilling rig (1). The drill rod (7) passes through the middle of the fastening device (2). The hydraulic propulsion device (3) includes an annular hydraulic cylinder, a piston that cooperates with the hydraulic cylinder, and an annular steel ring fixed to the front section of the piston; the hydraulic cylinder is mounted on the fastening device (2); The rock mass natural frequency zoning detection system includes a connector (4), an amplitude data transmission line (19), an amplitude data collection system (16), a detection frequency output line (10), and a natural frequency analyzer (11). The ultrasonic focusing excitation system includes an ultrasonic generator (13), a high-frequency current input line (12), a circuit control system (15), a power supply line (14), N sets of bases (5), a focusing acoustic lens (8), an amplitude transformer (6), a piezoelectric accelerometer (18), and an ultrasonic transducer (17). The connector (4) is ring-shaped and mounted on the annular steel ring; the base (5) is evenly distributed in a ring and fixed on the front end face of the connector (4), and the front end of the base (5) is provided with a mounting groove. The bottom end of the amplitude rod (6) is installed in the mounting groove, and the focusing acoustic lens (8) is hinged to the top end of the amplitude rod (6) through a rotating shaft (20), so that the focusing acoustic lens (8) can rotate toward the axis of the connector (4); the ultrasonic transducer (17) and the piezoelectric accelerometer (18) are installed at the bottom of the mounting groove. The piezoelectric accelerometer (18) is collected by the amplitude data transmission line (19) and sent to the amplitude data collection system (16), and transmitted to the natural frequency analyzer (11) by the detection frequency output line (10); The ultrasonic generator (13) has an adjustable frequency. Different ultrasonic electrical signals are input to the circuit control system (15) through the high-frequency current input line (12). The circuit control system (15) then inputs the different ultrasonic electrical signals to the N ultrasonic transducers (17) through the power supply line (14).

2. The ultrasonic focusing deep rock breaking auxiliary device according to claim 1, characterized in that, A buffer isolation layer is provided on the inner wall of the mounting slot.

3. The ultrasonic focusing deep rock breaking auxiliary device according to claim 2, characterized in that, The buffer isolation layer adopts a honeycomb metal structure.

4. The ultrasonic focusing deep rock breaking auxiliary device according to claim 3, characterized in that, The hydraulic propulsion device (3) also includes a pressure sensor and a hydraulic control system. The pressure sensor is used to detect the force state of the piston, and the hydraulic control system controls the oil pressure of the hydraulic propulsion device (3).

5. The ultrasonic focusing deep rock breaking auxiliary device according to claim 4, characterized in that, The amplitude data transmission line (19) and amplitude data collection system (16) are arranged inside or on the surface of the connector (4).

6. The ultrasonic focusing deep rock breaking auxiliary device according to claim 1, characterized in that, The focusing acoustic lens (8) is elliptical cylindrical, with the curved tip of the ellipse in close contact with the rock (9).

7. A dynamic excitation method for the ultrasonic focusing deep rock breaking auxiliary device as described in any one of claims 1 to 6, characterized in that, Includes the following steps:

1. Fix the drilling rig (1) to the construction area through the support structure, put the fastening device (2) on the outside of the drilling rig (1), pass the drill rod (7) through the middle of the fastening device (2), fix the auxiliary drilling device on the drilling rig (1), rotate the focusing acoustic lens (8) towards the drilling hole so that the initial excitation position of the ultrasonic wave is the surface of the rock (9), inject fluid into the hydraulic propulsion device (3), extend the piston, and press the focusing acoustic lens (8) tightly against the surface of the rock mass with a certain pressure. Place the natural frequency analyzer (11) and the adjustable frequency ultrasonic generator (13) on the ground and connect the high frequency current input line (12) and the detection frequency output line (10).

2. Start the drilling rig (1), the drill rod (7) applies a rotating impact to the rock mass, the rock mass natural frequency detection system receives and determines the natural frequency of the rock mass, the frequency-adjustable ultrasonic generator (13) generates a corresponding high-frequency current according to the detection result, the ultrasonic transducer (17) converts the high-frequency current into high-frequency mechanical vibration and excites the construction rock through the amplitude transformer (6) and the focusing acoustic lens (8).

3. During the drilling process of the drilling rig (1), the hydraulic propulsion device (3) automatically retracts the piston according to the drilling depth and adjusts the length of the auxiliary drilling device; the rock position at the top of the drill rod (7) is set as the predetermined focus, ensuring that the focusing acoustic lens (8) is always in close contact with the surface of the rock (9). At the same time, the focusing acoustic lens (8) also rotates outward according to the drilling depth, so that the ultrasonic waves from N units converge at the predetermined focus in the rock body in front of the drill rod (7) to form an ultrasonic focusing excitation point (22), which performs dynamic excitation of the rock in front of the drill rod (7) with great depth and high precision, reduces the rock strength, and achieves efficient drilling of the rock; as the drilling gradually deepens, it continues to rotate outward to adjust the angle of the focusing acoustic lens (8), so that the predetermined focus moves forward and the drilling continues; 4. After the rock drilling is completed, rotate the drilling rig (1) in the opposite direction to remove one drill rod, remove the drill rod, retract the piston on the hydraulic propulsion device (3), shut down the auxiliary drilling device, remove the high-frequency current input line (12) and the detection frequency output line (10), loosen the clamp of the fastening device (2), remove the auxiliary drilling device from the drilling rig (1), then connect the drilling rig (1) and the drill rod in the hole, remove the drill rod normally, and finally shut down the drilling rig and tidy up the construction area.

8. The dynamic excitation method for an ultrasonic focusing deep rock breaking auxiliary device according to claim 7, characterized in that, The rotation angle of the focusing acoustic lens (8) remains consistent.

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