Variable diameter device for full-section hard rock tunnel boring machine, method of use thereof, and full-section hard rock tunnel boring machine

Abstract

The present invention provides a variable diameter device for a full-section hard rock tunnel boring machine, a method for using the same, and a full-section hard rock tunnel boring machine. The variable diameter device for a full-section hard rock tunnel boring machine includes: a shield having a front shield and a rear shield connected to a tail portion of the front shield; a main drive unit provided inside the front shield and connected to a telescopic arm via a hinge unit; a variable diameter cutterhead having an outer cutterhead, an inner cutterhead, and a central cutterhead and connected to the main drive unit; a propulsion unit provided inside the front shield and moving the front shield; and an excavation unit provided on the outer cutterhead, wherein the main drive unit can move the variable diameter cutterhead along an axis relative to the shield and rotate the variable diameter cutterhead, and the outer cutterhead can be extended radially outward or retracted radially inward by the telescopic arm.

Description

[Technical Field]

[0001] The present invention relates to the technical field of tunnel construction equipment, and more particularly to a variable diameter device for a full-section hard rock tunnel boring machine and a method for using the same, as well as a full-section hard rock tunnel boring machine. [Background technology]

[0002] Currently, full-face hard rock tunnel boring machines are also abbreviated as TBMs.

[0003] TBM construction technology, a relatively advanced tunnel construction technology, has been widely applied in tunnel construction in the transportation and water conservancy sectors, demonstrating significant advantages in terms of quality, construction time, safety, environmental protection, and civilized construction. However, it has not been widely adopted in the construction of general hydroelectric power plants and pumped-storage power plants in China. Pumped-storage power plants are underground tunnels within a limited space, with many vertical intersections, short tunnels, many bends, and frequent changes in cross-sectional dimensions. However, the time-consuming and demanding assembly and disassembly of TBM equipment prevents its advantages in construction time from being fully realized in the construction of short tunnels or tunnels with different diameters. Currently, for tunnels with different diameters, conventional TBMs can only change the equipment diameter from large to small while in construction. To change from small to large diameter, the conventional method involves reassembly outside the tunnel or artificially excavating a tunnel at the change in diameter within the tunnel, replacing it with a TBM cutterhead with a different specification, and then re-excavating. However, these methods have problems with time-consuming equipment removal and installation and complicated auxiliary operations. Therefore, there is a need for a TBM that can significantly improve the adaptability and safety of underground tunnel excavation work for pumped storage power plants, increase construction efficiency, reduce construction costs, and achieve arbitrary diameter expansion and contraction within the tunnel. Summary of the Invention [Problem to be solved by the invention]

[0004] In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a TBM that is simple to operate and easy to assemble, and that can achieve continuous diameter changes within a tunnel.

[0005] The present invention has been made to solve at least one of the technical problems in the prior art. [Means for solving the problem]

[0006] Variable diameter full-section hard rock tunnel boring machines are also called variable diameter TBMs.

[0007] As a technical solution adopted by the present invention, in order to achieve the above and other related objects, the present invention provides a variable diameter device for a full-section hard rock tunnel boring machine.

[0008] The variable diameter device for a full-section hard rock tunnel boring machine includes a shield, a main drive unit, a variable diameter cutterhead, a propelling unit, and an excavating unit.

[0009] The shield includes a front shield and a rear shield connected to a tail portion of the front shield.

[0010] The main drive unit is provided inside the front shield and is connected to the telescopic arm via a hinge unit.

[0011] The variable diameter cutterhead includes an outer cutterhead, an inner cutterhead, and a central cutterhead, and is connected to a main drive unit that can move the variable diameter cutterhead along an axis relative to the shield and rotate the variable diameter cutterhead, and the outer cutterhead can be extended radially outward or retracted radially inward by a telescoping arm.

[0012] The propulsion unit is provided inside the front shield and moves the front shield.

[0013] The excavation section is provided on the outer cutterhead.

[0014] The main drive can move the variable diameter cutterhead relative to the shield along an axis, which can be the axis of advancement, the axis of the shield, or the axis of rotary cutting tunneling.

[0015] The technical solution provided by this application further has the following technical features:

[0016] Preferably, the outer cutter head includes an outer telescopic cutter head and a sub-outer cutter head, and the outer telescopic cutter head can rotate and extend along the circumferential direction of the outer cutter head and is connected to the sub-outer cutter head.

[0017] Preferably, the inner cutter head includes a bit extension and an extension bit, the working surfaces of the outer cutter head and the central cutter head are flush with each other, the extension bit is provided at the rear of the outer cutter head, and the working surface of the inner cutter head after extension is flush with that of the central cutter head.

[0018] Preferably, the telescoping bit is telescopically extended by a bit telescoping portion.

[0019] Preferably, the excavation unit includes a sliding pair and a reaming mechanism, the sliding pair is used to limit the position of the variable diameter cutter head and is provided in the radial path of the variable diameter cutter head, and the variable diameter cutter head is hingedly connected to one end of the telescopic arm.

[0020] Preferably, the excavation mechanism is provided at the outer end of the connection point between the excavation section and the front shield.

[0021] The technical solution provided by the present invention has obvious advantages in terms of structural strength, compact volume, production efficiency, production cost, and the characteristics of the structure itself.

[0022] Structural strength: The preferred variable diameter device adopts a structural design including an outer cutterhead and an inner cutterhead, which strengthens the structural strength of the entire device. The outer cutterhead is composed of an outer telescopic cutterhead and a secondary outer cutterhead, which can rotate and extend in the circumferential direction of the outer cutterhead and is connected to the secondary outer cutterhead. The inner cutterhead is composed of a central cutterhead and a telescopic bit, which is flush with the outer cutterhead and the telescopic bit is located at the rear of the outer cutterhead. This structural design improves the rigidity and stability of the entire variable diameter device and can handle high-intensity rock excavation work.

[0023] Compact volume: The preferred variable diameter equipment takes compact volume elements into consideration in its structural design. By adopting a design that includes an external telescopic cutter head and a secondary external cutter head, the variable diameter equipment can flexibly adjust the diameter during excavation to adapt to tunnels with different cross-sectional dimensions. This variable diameter design reduces the overall volume of the equipment, allowing it to be operated and moved in limited spaces, improving construction flexibility and adaptability.

[0024] Production efficiency: A preferred variable-diameter drilling device has high production efficiency. The telescopic bit is extended and retracted by the bit extension section, allowing the bit length to be adjusted as needed to adapt to drilling operations in different rock formations. At the same time, the drilling section includes a reaming mechanism and a sliding pair. The sliding pair is used to limit the position of the variable-diameter cutterhead, allowing it to move outward along a direction perpendicular to the axis of movement of the main drive section, i.e., along the radial path of the shield or outer cutterhead. The radial direction refers to the radius radiating outward from the center of the shield. The center of the radial movement of the sliding pair and the axis of the telescopic arm should be located on the same plane. This converts the relative rotational movement of the two ends of the telescopic arm into radial movement of the variable-diameter cutterhead. This structural design effectively improves drilling speed and production efficiency and shortens the construction cycle.

[0025] Production cost: The preferred variable diameter device has certain advantages in terms of production cost. Its structural design is relatively simple, and it adopts rational combination and layout, reducing the number of parts and manufacturing costs. At the same time, the device's compact size makes it easier to assemble and disassemble on-site, reducing transportation and installation costs.

[0026] By applying the above-mentioned variable diameter device for a full-section hard rock tunnel boring machine, a method for using the variable diameter device for a full-section hard rock tunnel boring machine is obtained, and the method includes a first step of preparing for diameter expansion, a second step of performing excavation expansion using a cutter head, and a third step of expanding the diameter of the cutter head.

[0027] In the first step, the main drive unit pushes the variable diameter cutter head to extend along the axial direction, excavating a certain distance forward to secure an expansion space.

[0028] In the second step, the sliding pair in the excavation section extends the outer cutter head in the radial direction, the outer cutter head is rotated by driving the main drive unit, and the expansion mechanism is further driven to expand the outer soil body to form an expansion space, and the main drive unit retracts the variable diameter cutter head in the axial direction, allowing the variable diameter cutter head to expand in the expansion space.

[0029] In the third step, the central cutter head maintains its original position, the outer cutter head is extended along the radial direction by the telescopic arm of the main drive unit and expanded to a predetermined diameter, the outer telescopic cutter head rotates and extends, and connects with the sub-outer cutter head to form a combined cutter head, and the telescopic bit on the inner cutter head is extended axially by driving the bit telescopic unit and kept flush with the bit on the outer cutter head.

[0030] Preferably, the method includes a fourth step of reducing the diameter of the cutter heads, in which the central cutter head maintains its original position, the telescopic bit on the inner cutter head is driven by the bit telescopic part to retract axially, the outer telescopic cutter head is separated from the sub-outer cutter head and rotates in the circumferential direction to retract, and the outer cutter head is driven by the telescopic arm to retract radially.

[0031] Preferably, in the fifth step, the propulsion unit is pressed against the rock mass of the tunnel wall to provide forward propulsion force to the machine body.

[0032] The variable diameter device for a full-section hard rock tunnel boring machine and the method for using the same are applied to obtain a full-section hard rock tunnel boring machine. [Effects of the Invention]

[0033] The beneficial effects of the present invention are as follows:

[0034] 1. The equipment of the present invention overcomes the problem that conventional TBMs have to be moved outside the tunnel or an additional access tunnel needs to be constructed to achieve diameter changes in the cutter head. The equipment of the present invention can achieve diameter changes in the cutter head inside the tunnel, eliminating the need to manually excavate tunnels for equipment installation at diameter changes, reducing the number of equipment assembly and disassembly processes, and shortening the construction period.

[0035] 2. According to the present invention, the diameter of the cutter head of the tunnel boring machine can be directly changed continuously and arbitrarily from large to small or from small to large, making it suitable for excavating tunnels with various diameters, with a wide range of applications and high construction efficiency.

[0036] 3. The present invention is simple to operate, does not require assembly or disassembly, and is easy to install. As described above, the present invention is easy to operate and assemble. Compared to conventional technologies, there is no need to evacuate the equipment outside the tunnel for disassembly and reassembly. The cutter head can be continuously expanded and contracted inside the tunnel, allowing tunnel cross sections with different diameters to be created. This significantly improves the quality, safety, and efficiency of construction work, increases adaptability to underground tunnel excavation work, and effectively reduces construction costs. [Brief explanation of the drawings]

[0037] [Figure 1] 1 is a cross-sectional structural schematic diagram of a variable diameter device for a full-section hard rock tunnel boring machine according to the present invention. [Figure 2] FIG. 2 is a schematic plan view of the structure of the variable diameter device for a full-section hard rock tunnel boring machine of the present invention before diameter change. [Figure 3] FIG. 2 is a schematic plan view of the structure of the variable diameter device for a full-section hard rock tunnel boring machine of the present invention after diameter change. DETAILED DESCRIPTION OF THE INVENTION

[0038] Specific embodiments of the present invention will be described in more detail below with reference to the drawings. Note that these embodiments are merely for the purpose of explaining the present invention and are not intended to limit the present invention.

[0039] In describing the present invention, it should be noted that directions or positional relationships indicated by terms such as "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "ceiling," "bottom," "inner," and "outer" are merely for convenience and simplification of the description of the present invention and do not expressly or imply that the subject devices or components must have a specific orientation or be constructed or operated in a specific direction. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are merely for convenience of description and should not be construed as expressing or implying relative importance.

[0040] It should be noted that in the description of the present invention, unless otherwise clearly defined and limited, the terms "attach," "couple," and "connect" should be interpreted broadly. For example, they may refer to a fixed connection, a detachable connection, or an integral connection. They may also refer to a mechanical connection or an electrical connection. They may also refer to a direct connection, an indirect connection via an intermediate medium, or internal communication between two components. Those skilled in the art can interpret the specific meanings of the above terms in the present invention according to the specific circumstances.

[0041] Also, unless otherwise specified, in the description of the present invention, "plurality" means two or more than two.

[0042] Example As shown in Figures 1 to 3, the variable diameter device for a full-section hard rock tunnel boring machine includes a shield 100 having a front shield 110 and a rear shield 120 connected to the tail portion of the front shield 110, a main drive unit 200 provided inside the front shield 110 and connected to a telescopic arm 220 via a hinge unit 210, a variable diameter cutterhead 300 having an outer cutterhead 310, an inner cutterhead 320 and a central cutterhead 321 and connected to the main drive unit 200, a propulsion unit 400 provided inside the front shield 110 and moving the front shield 110, and an excavation unit 500 provided on the outer cutterhead 310, wherein the main drive unit 200 can move the variable diameter cutterhead 300 along the axis relative to the shield 100 and rotate the variable diameter cutterhead 300, and the outer cutterhead 310 can be extended radially outward or retracted radially inward by the telescopic arm 220.

[0043] The present invention has the following features: Conventional TBMs can only change the diameter of their equipment from large to small during construction inside a tunnel. To change the diameter from small to large, the equipment must be reassembled outside the tunnel, or a service tunnel must be installed at the diameter change point inside the tunnel, and a TBM cutter head with a different specification must be installed and excavated again. Both of these methods have the drawbacks of requiring a long construction period and complicated equipment operation, which requires time and effort.

[0044] This embodiment provides a variable diameter device for a full-section hard rock tunnel boring machine. This device allows the cutter head to be continuously expanded and contracted inside the tunnel without the need to retract the equipment outside the tunnel for disassembly and reassembly, making it suitable for excavating tunnels with various diameters. This significantly improves the adaptability and safety of construction work, increases construction efficiency, and reduces construction costs.

[0045] The variable diameter cutterhead 300 includes an outer cutterhead 310, an inner cutterhead 320, and a central cutterhead 321. The variable diameter cutterhead 300 is connected to the main drive unit 200. The main drive unit 200 can move the variable diameter cutterhead 300 along an axis relative to the shield 100 and rotate the variable diameter cutterhead 300. The outer cutterhead 310 can be extended radially outward or retracted radially inward by a telescopic arm 220.

[0046] The outer cutter head 310 is located at the tip of the variable diameter cutter head 300 and is connected to the main drive unit 200. When driven by the main drive unit 200, it can expand radially outward or contract radially inward, thereby increasing or decreasing the diameter of the cutter head periphery. The inner cutter head 320 and the central cutter head 321 are both mounted on the main drive unit 200. The inner cutter head 320 is located at the rear of the variable diameter cutter head 300, and the central cutter head 321 is located at the center of the variable diameter cutter head 300.

[0047] The variable diameter cutterhead 300 provided in this embodiment is provided with an excavation unit 500. The excavation unit 500 is installed on the outer cutterhead 310 and includes a sliding pair 510 and an expanding mechanism 520. Before the variable diameter cutterhead 300 expands, the sliding pair 510 extends the expanding mechanism 520 in the radial direction, and the expanding mechanism 520 expands the rock mass. The variable diameter cutterhead 300 is driven by the main drive unit 200, and the translational rotation of the variable diameter cutterhead 300 causes the excavation unit 500 to expand the excavation space in the radial direction within the tunnel. This allows the full-section hard rock tunnel boring machine to change the diameter of the cutterhead from small to large within the tunnel.

[0048] Specifically, the outer cutter head 310 includes an outer telescopic cutter head 311 and a sub-outer cutter head 312. The outer telescopic cutter head 311 can rotate and extend / retract along the circumferential direction of the outer cutter head 310 and is connected to the sub-outer cutter head 312. This allows the diameter of the outer cutter head 310 to be adjusted as needed to accommodate tunnels with different cross-sectional dimensions.

[0049] Specifically, the inner cutter head 320 includes a bit telescopic part 322 and a telescopic bit 323. The outer cutter head 310 and the central cutter head 321 are flush with each other. The telescopic bit 323 is provided at the rear of the outer cutter head 310. The inner cutter head 320 can rotate and telescope under the positional constraints imposed by the connection with the outer cutter head 310, and can adapt to tunnels with different cross-sectional dimensions.

[0050] Specifically, the telescopic bit 323 is configured to be extendable by the bit telescopic part 322, and the bit telescopic part 322 provides a mechanism for controlling and adjusting the length of the cutter head, so that the telescopic bit 323 can be extended or contracted according to actual needs and adapted to the drilling work of different rock layers.

[0051] Specifically, the excavation unit 500 includes a sliding joint 510 and an expanding mechanism 520. The sliding joint 510 is used to limit the position of the variable diameter cutter head 300, and moves the variable diameter cutter head 300 outward along a direction perpendicular to the movement axis of the main drive unit 200. The telescopic arm 220 adjusts the telescopic position of the variable diameter cutter head 300 through the sliding joint 510, assists in outward expanding, and ensures the stability and accurate excavation of the cutter head.

[0052] Specifically, the excavation mechanism 520 is installed at the outer end to improve the construction efficiency and excavation quality.

[0053] A method for using a variable diameter device for a full-section hard rock tunnel boring machine includes a first step of preparing for diameter expansion, a second step of performing diameter expansion using a cutter head, and a third step of performing diameter expansion of the cutter head.

[0054] In the first step, the main driving unit 200 pushes the variable diameter cutter head 300 so that it extends in the axial direction, excavating a certain distance forward to secure an enlarged excavation space.

[0055] In the second step, the sliding pair 510 in the excavation section 500 extends the outer cutter head 310 in the radial direction, and the outer cutter head 310 is rotated by driving the main drive section 200, and the widening mechanism 520 is further driven to widen the outer soil body to form an widening space, and the main drive section 200 retracts the variable diameter cutter head 300 in the axial direction, thereby enabling the variable diameter cutter head 300 to widen in the widening space.

[0056] In the third step, the central cutter head 321 maintains its original position, and the outer cutter head 310 is extended along the radial direction under the position limit of the sliding joint 510 by the driving of the telescopic arm 220 of the main driving unit 200, and expands to a predetermined diameter. The outer telescopic cutter head 311 rotates and extends, and connects with the sub-outer cutter head 312 to form a combined cutter head, and the telescopic bit 323 on the inner cutter head 320 is extended axially by the driving of the bit telescopic part 322, and is kept flush with the bit of the outer cutter head 310.

[0057] Specifically, the fourth step includes reducing the diameter of the cutter head. In the fourth step, the central cutter head 321 maintains its original position, the telescopic bit 323 on the inner cutter head 320 is driven by the bit telescopic part 322 to retract axially, the outer telescopic cutter head 311 separates from the sub-outer cutter head 312 and rotates circumferentially to retract, and the outer cutter head 310 is driven by the telescopic arm 220 to retract radially.

[0058] Specifically, in the fifth step, the propulsion unit 400 is pressed against the rock mass of the tunnel wall to provide forward propulsion force to the machine body.

[0059] Specifically, an external telescopic cutterhead 311 is further provided at the rear of the outer cutterhead 310. After the outer cutterhead 310 is expanded in diameter by the main drive unit 200, the external telescopic cutterhead 311 extends from inside the sub-outer cutterhead 312 and rotates circumferentially until it connects with the adjacent sub-outer cutterhead 312. At the same time, the central cutterhead 321 remains stationary. After the outer cutterhead 310 expands in diameter, the inner cutterhead 320 is exposed to the surface, and a telescopic bit 323 and a bit telescopic portion 322 are installed on it. The telescopic bit 323 extends axially under the action of the bit telescopic portion 322 until it is flush with the bit on the outer cutterhead 310. When the cutterhead diameter is reduced, the telescopic bit 323 retracts axially under the action of the bit telescopic portion 322 and is hidden above the inner cutterhead 320. At the same time, the outer telescopic cutter head 311 separates from the sub-outer cutter head 312 and retreats by rotating in the opposite direction along the circumference, while the outer cutter head 310 reduces its diameter along the radial direction under the drive of the main drive unit 200. The propulsion unit 400 is installed inside the front shield 110 and moves the front shield 110.

[0060] As described above, the present invention includes a shield 100, a main drive unit 200, a variable diameter cutterhead 300, a propelling unit 400, and an excavation unit 500. The shield 100 includes a front shield 110 and a rear shield 120. The variable diameter cutterhead 300 includes an outer cutterhead 310 and an inner cutterhead 320. The inner cutterhead 320 and the outer cutterhead 310 are both connected to the main drive unit 200. The outer cutterhead 310 is provided with an external telescopic cutterhead 311, and the inner cutterhead 320 is provided with a telescopic bit 323 connected to a bit telescopic unit 322. The excavation unit 500 includes a sliding pair 510 and a reaming mechanism 520. At the same time, the present invention also provides a method for using a variable diameter TBM.

[0061] The method of using the variable diameter TBM equipment of this embodiment includes the following steps.

[0062] 1) Preparation for expanding the diameter: The main driving unit 200 pushes the variable diameter cutter head 300 so that it extends along the axial direction, excavating a certain distance forward to secure an expanding space.

[0063] 2) Expansion by cutter head: The sliding pair 510 in the excavation section 500 extends the outer cutter head 310 in the radial direction, and the outer cutter head 310 is rotated by driving the main drive section 200. The expansion mechanism 520 is then driven to expand the outer soil body to form an expansion space, and the main drive section 200 retracts the variable diameter cutter head 300 in the axial direction, allowing the variable diameter cutter head 300 to expand in the expansion space.

[0064] 3) Expanding the diameter of the cutter head: The central cutter head 321 remains in its original position, and the outer cutter head 310 is expanded radially by the telescopic arm 220 of the main drive unit 200 to expand to a predetermined diameter. The outer telescopic cutter head 311 rotates and expands, and connects with the sub-outer cutter head 312 to form a combined cutter head. The bit telescopic unit 322 drives the telescopic bit 323 on the inner cutter head 320 to extend axially and keep it flush with the bit of the outer cutter head 310.

[0065] 4) Cutter head contraction: The central cutter head 321 maintains its original position, the telescopic bit 323 on the inner cutter head 320 is retracted axially by the drive of the bit telescopic part 322, the outer telescopic cutter head 311 separates from the sub-outer cutter head 312 and rotates circumferentially to retract, and the outer cutter head 310 is retracted radially by the drive of the telescopic arm 220.

[0066] As described above, the present invention is widely applicable to the excavation of tunnels with different diameters. The present invention overcomes the drawbacks of conventional TBMs, which cannot continuously change diameters at will, resulting in the time, labor, and cost required for diameter changes. The equipment of the present invention achieves continuous diameter changes within a tunnel by radially extending and contracting the outer cutter head 310 and the axially extending and contracting bit of the inner cutter head 320. This eliminates the need to retract the equipment outside the tunnel for disassembly and reassembly, thereby improving tunnel excavation efficiency and reducing construction costs. It is particularly suitable for construction projects involving tunnels with various diameters. Furthermore, the present invention has advantages such as a simple structure, easy assembly and disassembly, simple operation, and high construction efficiency, thereby resolving the problem of TBMs being unable to continuously excavate tunnels with variable diameters.

[0067] The above description is merely a preferred embodiment of the present invention, and those skilled in the art may make minor modifications and substitutions without departing from the technical principles of the present invention, and these modifications and substitutions should also be considered to fall within the scope of protection of the present invention. [Explanation of symbols]

[0068] 100 Shield 110 Front Shield 120 rear shield 200 Main drive unit 210 Hinge part 220 Telescopic Arm 300 Variable Diameter Cutter Head 310 outer cutter head 311 External telescopic cutter head 312 Sub-outer cutter head 320 inner cutter head 321 Central Cutter Head 322 Bit extension 323 Telescopic Bit 400 Promotion Department 500 Excavation Section 510 Sliding Pair 520 Excavation mechanism

Claims

1. A variable diameter device for a full-section hard rock tunnel boring machine, a shield (100) including a front shield (110) and a rear shield (120) connected to a tail portion of the front shield (110); a main drive unit (200) provided inside the front shield (110) and connected to an extendable arm (220) via a hinge unit (210); a variable diameter cutterhead (300) comprising an outer cutterhead (310), an inner cutterhead (320) and a central cutterhead (321), and connected to the main drive (200); a propulsion unit (400) provided inside the front shield (110) and moving the front shield (110); a digging portion (500) provided on the outer cutter head (310); The variable diameter device for a full-section hard rock tunnel boring machine is characterized in that the main drive unit (200) can move the variable diameter cutter head (300) along an axis relative to the shield (100) and rotate the variable diameter cutter head (300), and the outer cutter head (310) can be expanded radially outward or contracted radially inward by the telescopic arm (220).

2. 2. The variable diameter device for a full-section hard rock tunnel boring machine as claimed in claim 1, wherein the outer cutter head (310) comprises an outer telescopic cutter head (311) and a sub-outer cutter head (312), and the outer telescopic cutter head (311) can rotate and extend along the circumferential direction of the outer cutter head (310) and is connected to the sub-outer cutter head (312).

3. 2. The variable diameter device for a full-section hard rock tunnel boring machine according to claim 1, wherein the inner cutter head (320) comprises a bit telescopic part (322) and a telescopic bit (323), the working surfaces of the outer cutter head (310) and the central cutter head (321) are flush with each other, the telescopic bit (323) is provided at the rear of the outer cutter head (310), and the working surface of the inner cutter head (320) after extension is flush with that of the central cutter head (321).

4. 2. The variable diameter device for a full-section hard rock tunnel boring machine according to claim 1, wherein the excavation unit (500) comprises a sliding pair (510) and a reaming mechanism (520), the sliding pair (510) is used to limit the position of the variable diameter cutter head (300) and is provided in the radial path of the variable diameter cutter head (300), and the variable diameter cutter head (300) is hingedly connected to one end of the telescopic arm (220).

5. The first step is to prepare for expansion; A second step of enlarging the excavation with a cutter head; and a third step of expanding the diameter of the cutter head, In the first step, the main driving unit (200) pushes the variable diameter cutter head (300) to extend along the axial direction, excavating a certain distance forward to secure an enlarged excavation space; In the second step, the sliding pair (510) in the excavation section (500) extends the outer cutter head (310) along the radial direction, the outer cutter head (310) is rotated by driving the main drive section (200), and the enlarging mechanism (520) is further driven to enlarge the outer soil body to form an enlarged diameter space, and the main drive section (200) retracts the variable diameter cutter head (300) in the axial direction, thereby enabling the variable diameter cutter head (300) to enlarge in the enlarged diameter space; In the third step, the central cutter head (321) maintains its original position, the outer cutter head (310) is extended along the radial direction by the telescopic arm (220) of the main driving unit (200) to expand to a predetermined diameter, the outer telescopic cutter head (311) rotates and extends, and connects with the sub-outer cutter head (312) to form a combined cutter head, and the telescopic bit (323) on the inner cutter head (320) is extended axially by driving the bit telescopic unit (322), and is kept flush with the bit of the outer cutter head (310).

6. a fourth step of reducing the diameter of the cutter head; 6. The method for using a variable diameter device for a full-section hard rock tunnel boring machine according to claim 5, wherein in the fourth step, the central cutterhead (321) maintains its original position, the telescopic bit (323) on the inner cutterhead (320) is retracted axially by driving the bit telescopic part (322), the outer telescopic cutterhead (311) is separated from the sub-outer cutterhead (312) and rotates circumferentially to retract, and the outer cutterhead (310) is retracted radially by driving the telescopic arm (220).

7. 7. The method for using a variable diameter device for a full-section hard rock tunnel boring machine according to claim 6, wherein in the fifth step, the propulsion unit (400) is pressed against the rock mass of the tunnel wall to provide forward propulsion force to the machine body.

8. A full-section hard rock tunnel boring machine, characterized in that it employs a variable diameter device for a full-section hard rock tunnel boring machine according to any one of claims 1 to 4.

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