Support structure for shield machine expansion process and construction method thereof

Abstract

The application relates to the technical field of tunnel construction, and discloses a supporting structure for a shield machine expansion process and a construction method thereof, which comprises a limiting connecting piece and multiple closed segment units. The multiple closed segment units are sequentially connected in a head-to-tail mode in a circumferential direction to define a closed ring. The limiting connecting piece is radially arranged between two adjacent closed segment units, and the limiting connecting piece is respectively connected with the two adjacent closed segment units. The closed ring is arranged on the outer periphery of a shield body and located at the rear of the shield body in the axial direction of a cutter head. The closed ring has a supporting surface arranged in the axial direction and away from the shield body to abut against a soil body. The application can adapt to the variable-diameter shield construction process, support in time, and can be assembled in a narrow space, is mechanically stable, and is convenient to install.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a support structure and its construction method for the tunnel boring machine's diameter expansion process. Background Technology

[0002] In urban rail transit construction, variable-diameter shield tunneling technology has become a key means to achieve integrated station-tunnel construction, addressing the pain points of open-cut construction in core areas, such as large land occupation, strong interference, long construction period, and high risks associated with mining methods. This technology uses the same shield machine, maintaining a small diameter during tunnel excavation in the initial section, then expanding the diameter for large-diameter excavation upon reaching the station location, and subsequently reducing the diameter to continue construction on the next section, thus directly completing continuous tunnel-station construction underground. This method eliminates the need for traditional step-by-step dismantling operations, significantly improving construction efficiency and substantially reducing interference with the surface environment.

[0003] However, the expansion process of a variable-diameter tunnel boring machine (TBM) typically needs to be carried out in stages, following the sequence of "cutterhead—shield—tail." The cutterhead must complete its expansion before the shield and tail and begin excavation. This results in a section of unsupported annular "free face" between the cutterhead after expansion and the shield, which has not yet followed. (See attached reference) Figure 1 The exposed surface of this soil is highly susceptible to collapse, deformation, or water leakage under the combined effects of its own weight, the pressure of the overlying soil layer, and the surrounding water and soil pressure. This not only directly threatens the safety of construction and equipment but may also lead to deviations in the accuracy of subsequent shield assembly, seriously affecting the overall reliability of the integrated station-tunnel structure.

[0004] Existing tunnel support technologies are ill-suited to this unique variable-diameter working condition. On one hand, traditional segment assembly requires the shield tail to disengage, making "instant support" impossible after the cutterhead is enlarged, resulting in prolonged exposure of the free face. On the other hand, the working space in the soil chamber behind the cutterhead is extremely limited, making cast-in-place lining or rebar tying impossible. Furthermore, bolt connections for traditional segments rely on manual entry into the chamber, posing significant safety risks to personnel. Therefore, there is an urgent need to develop a soil support structure that can adapt to the variable-diameter shield tunneling process, achieve rapid mechanized assembly in confined spaces, and possess stable mechanical properties, thus providing safety assurance for integrated station-tunnel construction. Summary of the Invention

[0005] The purpose of this invention is to provide a support structure and its construction method that can adapt to the variable diameter shield tunneling construction process, provide timely support, can be assembled in confined spaces, is mechanically stable, and is easy to install for the shield tunneling machine's diameter expansion process.

[0006] To achieve the above objectives, the present invention provides a support structure for the diameter expansion process of a tunnel boring machine (TBM), comprising: a limiting connector and multiple closed segment units, wherein the multiple closed segment units are connected end to end in a circumferential direction to form a closed ring, the limiting connector is radially inserted between two adjacent closed segment units, and the limiting connector is respectively engaged with two adjacent closed segment units, the closed ring is used to be sleeved on the outer periphery of the shield body of the TBM and located behind the cutterhead of the TBM in the axial direction, and the closed ring has a support surface for being axially opposed to the shield body of the TBM and abutting against the soil.

[0007] Furthermore, it also includes multiple support segment units, which are connected end to end in the circumferential direction to form a support ring. Adjacent support segment units are interlocked. The support ring is used to be fitted onto the shield body. One axial end of the support ring is connected to the side of the closed ring that is axially away from the support surface. The outer peripheral wall of the support ring is used to abut against the soil.

[0008] Furthermore, the closed tube segment unit has a first side and a second side arranged opposite to each other in the circumferential direction. The first side has a first snap-fit ​​groove that extends axially and is at least unidirectionally through. The second side has a first sliding snap-fit ​​part that extends axially. The first snap-fit ​​groove and the first sliding snap-fit ​​part are slidably connected to realize the limiting connection of two adjacent closed tube segment units.

[0009] Furthermore, the closed segment unit has an inner side facing the shield body in the radial direction. Both the first side and the second side are provided with a second snap-fit ​​groove extending in the radial direction. The second snap-fit ​​groove extends unidirectionally to the inner side. The limiting connector is provided with a second sliding snap-fit ​​part on each of its opposite sides. The limiting connector passes through the second snap-fit ​​groove from the inner side and snaps with the closed segment unit through the second sliding snap-fit ​​part.

[0010] Furthermore, it also includes anchor bolts, wherein the closed segment unit has an axially penetrating anchor bolt hole, and / or the support segment unit has a radially penetrating anchor bolt hole; the anchor bolt passes through the anchor bolt hole and connects with the soil.

[0011] Furthermore, the support segment unit has two connecting sides arranged opposite each other in the circumferential direction. A third snap-fit ​​groove extending axially and passing through one direction is provided on the connecting side. The connecting side also has a third sliding snap-fit ​​part extending axially. The third sliding snap-fit ​​part and the third snap-fit ​​groove are arranged opposite each other in the axial direction. Two adjacent support segment units are snapped together by the third sliding snap-fit ​​part and the third snap-fit ​​groove.

[0012] Furthermore, it also includes a fixing connector. The closed segment unit has a first fixing connection hole on the side facing away from the support surface in the axial direction. The support segment unit is connected to the fixing connector on the side facing the closing ring in the axial direction. The fixing connector passes through the first fixing connection hole to connect the support segment unit and the closed segment unit.

[0013] Furthermore, it includes multiple support rings, which are connected sequentially along the axial direction. The closed segment unit has a second fixed connection hole on the side facing away from the closed ring in the axial direction. Adjacent support rings are connected by the fixed connector and the second fixed connection hole.

[0014] Furthermore, the first snap-fit ​​groove has a limiting groove extending along the extension direction of the first snap-fit ​​groove in its groove wall, and the first sliding snap-fit ​​part has a limiting part extending along the extension direction of the first sliding snap-fit ​​part protruding therefrom, the limiting part being in limiting cooperation with the limiting groove.

[0015] This invention also provides a construction method for a support structure used in the tunnel boring machine's diameter expansion process, comprising the following steps: S1 cutterhead expansion: When the variable diameter shield machine excavates to the preset expansion point, the cutterhead is controlled to perform radial rock breaking and expansion excavation until the cutterhead diameter reaches the designed expansion diameter; S2 creates working space: After the cutterhead is enlarged, the tunnel boring machine is controlled to advance forward a preset distance, leaving working space between the cutterhead and the shield body; S3 Installation of the closed ring: The closed segment unit is transported to the working space, and the robotic arm on the tunnel boring machine is used to grab and install the closed segment unit piece by piece. After each pair of adjacent closed segment units are assembled in place, a limiting connector is inserted at the connection point for fixation until the installation of the entire closed ring is completed. S4 Closed Ring Anchoring Grouting: After the closed ring is installed, anchor bolts are driven into the surrounding rock axially through the anchor bolt holes on the closed segment unit, and grouting is performed; S5 Installing the support ring: Control the tunnel boring machine to advance a support ring axial distance, transport the support segment unit to the work space, and use a robotic arm to grab and install the support segment unit piece by piece; S6 Support Ring Anchoring Grouting: After the support ring is installed, anchor bolts are driven radially into the surrounding rock through the anchor bolt holes on the support segment unit, and grouting is performed; S7 Cycle Construction: Control the tunnel boring machine to continue tunneling forward, repeating S5 and S6 until the construction of the subsequent support structure is completed.

[0016] Compared with existing technologies, the support structure and construction method for the tunnel boring machine diameter expansion process according to embodiments of the present invention have the following advantages: The support structure and construction method for the tunnel boring machine (TBM) diameter expansion process according to embodiments of the present invention, by setting a closed ring behind the cutterhead and formed by multiple closed segment units connected end to end, can promptly fill the free surface of the soil formed after the TBM diameter expansion, providing effective support for the surrounding rock and preventing collapse and instability. The segmented segment units are designed to be small in size and light in weight, suitable for the narrow working space behind the cutterhead and meeting the needs of small machinery for gripping. In particular, the connection method using limit connectors that pass radially and snap onto the segment units eliminates the need for complex bolt connections, enabling fully automatic and rapid locking and assembly by machinery without manual entry into the tunnel. This achieves "excavation and support immediately" during the diameter expansion process, significantly reducing construction risks and improving operational efficiency while ensuring the overall structural stability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the free surface of soil created by the tunnel boring machine's diameter change. Figure 2 This is a schematic diagram of the support structure used in the tunnel boring machine diameter expansion process according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the enclosed segment unit in an embodiment of the present invention; Figure 4 This is a schematic diagram showing the connection between the first snap-fit ​​groove and the first sliding snap-fit ​​part in an adjacent closed tube segment unit in an embodiment of the present invention; Figure 5 This is a planar schematic diagram of the inner side of the enclosed tube segment unit in an embodiment of the present invention; Figure 6 This is a schematic diagram of the installation of the enclosed segment unit in an embodiment of the present invention; Figure 7 This is a schematic diagram of the closed ring structure in an embodiment of the present invention; Figure 8 This is an isometric view of the enclosed segment unit in an embodiment of the present invention; Figure 9 This is a schematic diagram of the structure of the support segment unit in an embodiment of the present invention; Figure 10 This is a schematic diagram of the installation of the support segment unit in an embodiment of the present invention; Figure 11 This is a schematic diagram of the connection between the fixed connector and the second fixed connection hole in an embodiment of the present invention; Figure 12 This is a schematic diagram of the structure of the third snap-fit ​​groove and the third sliding snap-fit ​​part on the connecting side of the support segment unit in an embodiment of the present invention; Figure 13 This is a schematic diagram of the support ring structure in an embodiment of the present invention; Figure 14 This is an isometric view of the support segment unit in an embodiment of the present invention.

[0018] In the diagram, 10 is the free face of the soil; 11 is the cutterhead; 12 is the shield body; and 13 is the surrounding rock. 2. Closed ring; 20. Support surface; 3. Enclosed segment unit; 31. First side; 32. Second side; 33. First snap-fit ​​groove; 331. Limiting groove; 34. First sliding snap-fit ​​part; 341. Limiting part; 35. Inner side; 36. Second snap-fit ​​groove; 37. First fixed connection hole; 5. Support ring; 6. Support segment unit; 61. Connecting side; 62. Third snap-fit ​​groove; 63. Third sliding snap-fit ​​part; 64. Second fixed connection hole; 7. Anchor bolt; 70. Anchor bolt hole; 8. Fixed connectors; x, axial direction. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0020] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" used to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0021] In the description of this invention, it should be understood that the terms "connected," "linked," and "fixed," etc., used in this invention 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 a welded 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, unless otherwise explicitly defined. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] In this invention, the terms "first," "second," etc., are used to describe various types of information, but this information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this invention, "first" information can also be referred to as "second" information, and similarly, "second" information can also be referred to as "first" information.

[0023] The tunnel boring machine in this embodiment of the invention includes a cutterhead 11 and a shield body 12. The cutterhead 11 is located at the front end of the shield body 12 along the axial x direction, and the cutterhead 11 can radially expand its outer diameter. During the expansion process, the outer diameter of the cutterhead 11 is larger than the outer diameter of the shield body 12.

[0024] Reference Figure 2 and Figure 3 An embodiment of the present invention provides a support structure for the expansion process of a tunnel boring machine, comprising: a limiting connector and multiple closed segment units 3, wherein the multiple closed segment units 3 are connected end to end in the circumferential direction to form a closed ring 2, the limiting connector is radially inserted between two adjacent closed segment units 3, and the limiting connector is respectively engaged with two adjacent closed segment units 3, the closed ring 2 is sleeved on the outer periphery of the shield body 12 and located behind the cutterhead 11 in the axial x direction, and the closed ring 2 has a support surface 20 for abutting against the soil in the axial x direction away from the shield body 12.

[0025] In this embodiment, the multiple closed segment units 3 are prefabricated fan-shaped components, preferably made of high-strength steel or ductile iron, to meet the requirements of "small size, light weight" and ease of mechanical handling. The multiple closed segment units 3 are connected end-to-end along the circumference, thus forming a complete circular structure, namely the closed ring 2. The closed ring 2 is fitted around the outer periphery of the shield body 12 and is located behind the cutterhead 11 in the x-axis direction. Specifically, after the cutterhead 11 completes the excavation and advances a certain distance, the closed ring 2 is assembled in the space vacated between the back of the cutterhead 11 and the outer periphery of the shield body 12. The closed ring 2 has a support surface 20 axially opposite to the shield body 12 for contacting the soil. This support surface 20 directly faces the exposed surrounding rock 13 step surface after excavation or serves as the starting support surface for subsequent support structures, thus sealing the soil and preventing longitudinal collapse.

[0026] To achieve rapid, unmanned connection within a confined space, adjacent enclosed segment units 3 are fixed together by the limiting connector. Specifically, the limiting connector is radially inserted between adjacent enclosed segment units 3. That is, during assembly, the robotic arm does not need to perform complex circular movements or axial tightening of bolts; it only needs to insert the limiting connector radially, from the center outwards or from the outside towards the center, preferably from the shield body 12 side outwards, into the joint of the adjacent segment unit.

[0027] During variable-diameter shield tunneling, the lightweight enclosed segment unit 3 is transported to the rear of the cutterhead 11 using the shield machine's built-in or attached robotic arm. The robotic arm first positions and assembles the segment unit, then grabs the limiting connector and inserts it radially into the joint. Due to the radially inserted snap-fit ​​method, the assembly process is simple and the path is short, avoiding manual bolt insertion in the narrow, muddy soil chamber, greatly improving assembly efficiency and safety. The assembled closed ring 2 quickly supports the expanded soil surface 10, ensuring the safety of subsequent construction.

[0028] Reference Figure 9 and Figure 14 In some improvements of this application, multiple support segment units 6 are also included. These support segment units 6 are sequentially connected end-to-end along the circumferential direction to form a support ring 5. Adjacent support segment units 6 are interlocked. The support ring 5 is fitted onto the shield body 12 and is located between the cutterhead 11 and the closing ring 2. One end of the support ring 5 in the x-axis direction is connected to the side of the closing ring 2 facing away from the support surface 20 in the x-axis direction. The outer peripheral wall of the support ring 5 is used to abut against the soil. After the cutterhead 11 of the variable-diameter shield machine completes its initial diameter expansion and the first closing ring 2 is installed, as the shield machine continues to advance, the distance between the cutterhead 11 and the relatively fixed closing ring 2 increases, forming a new working space. The support ring 5 is installed within this space, located between the cutterhead 11 and the closing ring 2. One end (usually the rear end) of the support ring 5 along the x-axis is connected to the side of the closing ring 2 facing away from the support surface 20 along the x-axis (i.e., the front end face of the closing ring 2). This connection can be achieved through a pre-installed pin, a fixing connector 8, or a convex-concave fit structure. Through this connection, the support ring 5 is anchored to the closing ring 2, preventing it from moving forward with the tunnel boring machine or tilting. After installation, the outer peripheral wall of the support ring 5 is in direct contact with the excavated soil. Depending on the geological conditions, grouting can also be performed behind the support ring 5 to ensure that the support ring 5 is tightly fitted with the surrounding rock 13 and shares the ground pressure.

[0029] After the installation of the closed ring 2 is completed, the tunnel boring machine advances a distance equal to the width of one support ring 5. At this point, the robotic arm grabs the support segment units 6 and assembles them sequentially in front of the closed ring 2. Each assembled segment is engaged with the adjacent support segment unit 6 and fixed to the closed ring 2 behind it or to the assembled complete support ring 5. This process is repeated, with the tunnel boring machine continuously advancing, installing support rings 5 ​​one after another until the tunnel support for the entire enlarged section is completed.

[0030] Reference Figure 8In some improvements of this application, the closed tube segment unit 3 has a first side 31 and a second side 32 arranged opposite to each other in the circumferential direction. The first side 31 has a first snap-fit ​​groove 33 extending along the axial x and passing through in at least one direction. The second side 32 has a first sliding snap-fit ​​part 34 extending along the axial x. The first snap-fit ​​groove 33 and the first sliding snap-fit ​​part 34 are slidably connected to realize the limiting connection of two adjacent closed tube segment units 3.

[0031] The engagement of the first locking groove 33 and the first sliding locking part 34 provides a natural guide for the assembly of the enclosed segment unit 3. In the narrow and poorly oriented environment of the soil chamber behind the cutterhead 11, the robot arm only needs to slide the first sliding locking part 34 of the enclosed segment unit 3 into the groove of the first locking groove 33 of the previous enclosed segment unit 3, and the subsequent installation process can be automatically aligned circumferentially. This self-guiding function significantly reduces the stringent requirements on the control precision of the robot arm and reduces the assembly and adjustment time. Once the first sliding locking part 34 slides into the first locking groove 33, the relative displacement of two adjacent enclosed segment units 3 in the radial (perpendicular to the circumferential direction) and circumferential (circumferential tangential) directions is restricted, retaining only the axial x-degree of freedom. During the assembly process, the segments will not experience radial misalignment or outward breakage, providing a stable geometric state for the subsequent insertion and final locking of the radial limiting connector, ensuring the safety of the construction process.

[0032] The closed segment unit 3 structure in the above embodiment is the standard closed segment of this application. This application may also have other closed segment units 3 with different structures. For example, the first closed segment unit 3 installed during actual installation is called block C; the last closed segment unit installed is called block F; and the closed segment units 3 adjacent to block F are respectively called L1 block level and L2 block. The first side 31 and the second side 32 of block C are provided with the snap-fit ​​groove, but the first sliding snap-fit ​​member is not provided.

[0033] Reference Figure 5 In some improvements of this application, the closed segment unit 3 has an inner side 35 that is radially oriented toward the shield body 12. The first side 31 and the second side 32 are both provided with a second snap-fit ​​groove 36 extending radially. The second snap-fit ​​groove 36 extends unidirectionally to the inner side 35. The limiting connector is provided with a second sliding snap-fit ​​part on each of its opposite sides. The limiting connector passes through the second sliding snap-fit ​​part from the inner side 35 into the second snap-fit ​​groove 36 and snaps with the closed segment unit 3.

[0034] Specifically, two adjacent enclosed tube segments 3 have semi-open second locking grooves 36 reserved on their mating sides, namely the first side 31 and the second side 32. When the two enclosed tube segments 3 are joined together, the two adjacent second locking grooves 36 merge at the joint to form a complete receiving groove that opens to the inner side 35. The limiting connector has second sliding locking parts protruding on opposite sides. For example, the second locking groove 36 is a T-shaped groove, and the limiting connector as a whole can be an H-shaped or dumbbell-shaped structure. Its size design allows the limiting connector to slide into the groove from the opening of the inner side 35, but it cannot be pulled out in the axial x direction, thus achieving fixed locking of the two adjacent enclosed tube segments 3 in the axial x direction. By using a simple radial pushing action, the traditional multi-bolt fastening action is replaced, achieving a fast and high-strength connection.

[0035] In some improvements of this application, anchor bolts 7 are also included. The closed segment unit 3 has an axially penetrating anchor bolt hole 70, and / or the support segment unit 6 has a radially penetrating anchor bolt hole 70. The anchor bolt 7 passes through the anchor bolt hole 70 and connects to the soil. By setting the anchor bolt 7, the prefabricated closed segment unit 3 or support segment unit 6 structure is tightly connected to the surrounding deep stable rock and soil. The anchoring force of the anchor bolt 7 can firmly nail the segment unit to the surrounding rock 13, so that the support structure is no longer just loosely resting on the excavation face, but forms a composite retaining structure with the surrounding rock 13 that shares the load, significantly improving the support system's ability to resist deformation, collapse, and vibration of the surrounding rock 13.

[0036] Reference Figure 12 In some improvements of this application, the support segment unit 6 has two connecting side surfaces 61 arranged opposite each other in the circumferential direction. A third snap-fit ​​groove 62 extending along the axial x and passing through in one direction is provided on the connecting side surface 61. The connecting side surface 61 also has a third sliding snap-fit ​​part 63 extending along the axial x. The third sliding snap-fit ​​part 63 and the third snap-fit ​​groove 62 are arranged opposite each other along the axial x. Two adjacent support segment units 6 are snapped together by the third sliding snap-fit ​​part 63 and the third snap-fit ​​groove 62.

[0037] The engagement of the third locking groove 62 and the third sliding locking part 63 forms a set of high-precision guide rails. During the sliding process, this structure forces adjacent support segment units 6 to remain radially flush, effectively preventing misalignment caused by self-weight or assembly errors. This not only ensures the smoothness of the outer surface of the support ring 5, enabling it to evenly support the soil, but also provides a flat inner wall for equipment passage within the internal space. When the third sliding locking part 63 enters the third locking groove 62, the circumferential freedom of adjacent support segment units 6 is restricted. This geometrically interlocking structure can directly withstand the circumferential tensile or shear forces caused by the pressure from the surrounding rock 13, preventing the support ring 5 from collapsing under soil pressure.

[0038] Reference Figure 11 In some improvements of this application, a fixing connector 8 is also included. The closed segment unit 3 has a first fixing connection hole 37 on the side facing away from the support surface 20 in the axial x direction. The support segment unit 6 has the fixing connector 8 on the side facing the closed ring 2 in the axial x direction. The fixing connector 8 passes through the first fixing connection hole 37 to connect the support segment unit 6 and the closed segment unit 3. Through the cooperation of the fixing connector 8 and the first fixing connection hole 37, the newly assembled support ring 5 is firmly anchored on the already stably installed closed ring 2. When the robot arm picks up the support segment unit 6 for installation, the process of the fixing connector 8 being inserted into the first fixing connection hole 37 completes the alignment and positioning of the segment.

[0039] In some improvements of this application, multiple support rings 5 ​​are included, which are sequentially connected along the axial direction x. The closed segment unit 3 has a second fixed connection hole 64 on the side facing away from the closed ring 2 along the axial direction x. Adjacent support rings 5 ​​are connected by the fixed connector 8 and the second fixed connection hole 64. By simultaneously providing the fixed connector 8 and the fixed connection hole on the support segment unit 6, the support rings 5 ​​on the support structure can extend infinitely, ring after ring, as the variable-diameter shield machine continues to advance, solving the support problem when the length of the enlarged section is not fixed, and achieving full coverage closure of the entire enlarged section.

[0040] Specifically, the outer peripheral wall of the fixing connector 8 is provided with a first step structure facing inward, and the first fixing connection hole 37 is provided with a second step structure facing outward, which is adapted to the first step structure. Both the fixing connector 8 and the hole wall of the fixing connection hole can be made of toughened modified polyamide material, which has a certain degree of elasticity. After the fixing connector 8 is inserted into the hole wall of the fixing connection hole, the first step structure and the second step structure engage with each other to form a self-locking mechanism, thus fixing the two together.

[0041] Reference Figure 4In some improvements of this application, the first snap-fit ​​groove 33 has a limiting groove 331 extending along the extending direction of the first snap-fit ​​groove 33 on its groove wall, and the first sliding snap-fit ​​part 34 has a limiting part 341 extending along the extending direction of the first sliding snap-fit ​​part 34 protruding on its surface. The limiting part 341 and the limiting groove 331 are mutually limitingly engaged. After the first sliding snap-fit ​​part 34 slides into the first snap-fit ​​groove 33, it forms a mechanical engagement with the limiting groove 331 through the limiting part 341, so that the relative separation of two adjacent closed segment units 3 in the radial and circumferential directions can be restricted before the final limiting connector is inserted. Even after the robot releases its grip or before the limiting connector is inserted, it will not fall inward or break outward due to its own weight or local soil pressure, greatly improving construction safety. This composite section design also further increases the contact area, which helps to disperse stress and improve the service life of the joint. The specific structure and fitting method of other sliding snap-fit ​​parts and snap-fit ​​grooves in this application can be referred to the first sliding snap-fit ​​part 34 and the first snap-fit ​​groove 33.

[0042] This application also provides an embodiment of a construction method for a support structure used in the tunnel boring machine's diameter expansion process, comprising the following steps: S1 cutterhead 11 diameter expansion: When the variable diameter tunnel boring machine (TBM) advances to the preset diameter expansion point, the cutterhead 11 is controlled to expand radially and break rocks for excavation until the outer diameter of the cutterhead 11 reaches the designed excavation diameter. At this time, the diameter of the cutterhead 11 is larger than the diameter of the shield body 12.

[0043] S2 Formation of Working Space: After the cutterhead 11 is enlarged, the tunnel boring machine (TBM) is controlled to advance forward a preset distance. In this embodiment, the preset distance is equal to the width of the TBM's cutting ring. This cutting ring refers to a section of the shield shell structure located behind the cutterhead 11 and at the foremost end of the shield body 12. It is a removable shield shell section specially designed for the TBM and does not affect its normal operation. After the TBM has reached its destination, the cutting ring shield shell is mechanically removed or cut off. After the cutting ring is cut off, a ring-shaped working space is exposed and formed between the enlarged cutterhead 11 and the remaining shield body 12, providing a space for subsequent segment assembly.

[0044] S3 Installation Closed Loop 2: Refer to Figure 6 and Figure 7The closed segment unit 3 is transported to the working space, and the robotic arm on the tunnel boring machine (TBM) grabs and installs the closed segment unit 3 piece by piece with the help of hydraulic cylinders. The specific assembly sequence is as follows: First, install the first closed segment unit 3 at the bottom as block C. After block C is in place, immediately perform bottom grouting to ensure that the bottom of block C is densely filled with soil, providing a stable base for the entire ring; then, with block C as the center, alternately assemble the standard blocks on the left and right sides of block C. That is, assemble them alternately upwards in the order of left block and right block. Whenever an adjacent closed segment unit 3 is assembled, a limiting connector is inserted radially at the joint of the two segments, i.e., the aforementioned second locking groove 36, using a robotic arm or auxiliary device. In this embodiment, the limiting connector is specifically an H-beam. After the H-beam is inserted, it firmly locks the two adjacent closed segment units 3. Repeat the above process until the sealing installation of the entire closed ring 2 is completed.

[0045] S4 Closed Ring 2 Anchoring Grouting: After the closed ring 2 is installed and locked, the tunnel boring machine drives anchor bolts 7 into the surrounding rock 13 formed by the excavation step surface through the axial x-anchor bolt holes 70 reserved on each closed segment unit 3. Grouting is then carried out, and the grout fills the pores and wraps the anchor bolts 7, firmly anchoring the closed ring 2 to the original soil and preventing axial x-displacement.

[0046] S5 installation support ring 5: Refer to Figure 10 and Figure 13 After the completion of the closed ring 2, continuous support construction begins. The tunnel boring machine is controlled to advance one stroke, which is equal to the axial x dimension of one support ring 5. The support segment unit 6 is transported to the working space and picked up by a robotic arm.

[0047] The specific assembly sequence is as follows: First, install the first support segment unit 6 located at the bottom, and connect it to the corresponding closed segment unit 3 using the fixing connector 8. After installation, perform bottom grouting to ensure the bottom is filled densely. Subsequently, alternately use a robotic arm and hydraulic cylinders to assemble the standard blocks on the left and right sides of the support segment unit 6. During the assembly process, the third sliding locking part 63 on the side and the third locking groove 62 are used to achieve interlocking within the ring, and at the same time, axial x-connection is made with the corresponding closed segment unit 3 behind. Repeat the above steps until the installation of a complete support ring 5 is completed.

[0048] S6 Support Ring 5 Anchoring Grouting: After the support ring 5 is installed, anchor rods 7 are driven radially into the surrounding rock 13 through the pre-reserved radial anchor bolt holes 70 on the support segment unit 6, and grouting is performed. S7 Cycle Construction: Control the tunnel boring machine to continue excavating forward, repeating S5 and S6 until the subsequent support structure construction is completed. Control the tunnel boring machine to continue excavating one ring's distance, repeating steps S5 and S6. That is: after each ring is excavated, install the bottom sealing management unit, grout, install the standard blocks on both sides, drive in the radial anchor bolts 7 and grout. Repeat this cycle until the tunnel boring machine completes the diameter expansion section.

[0049] In a specific embodiment of this application, the engineering parameters are as follows: The original outer diameter of the variable-diameter tunnel was 8.5m, and the outer diameter after the change was 11.6m; the outer diameter of the shield body 12 of the tunnel boring machine was 8.8m before the expansion and 11.9m after the change; the width of the cutting ring behind the cutterhead 11 was 1m; the diameter of the excavation of the cutterhead 11 was 12.4m.

[0050] The support structure parameters are as follows: The closed ring 2 has an outer diameter of 12.4m, an inner diameter of 8.9m, and a thickness of 0.4m. It is divided into 25 blocks in the circumferential direction, including the first block C at the bottom; 10 standard blocks B2 to the left of block C; 11 standard blocks B1 to the right of block C; and one sealing block F and one block L1 and L2 to its left and right.

[0051] The support steel ring has an outer diameter of 12.4m, an inner diameter of 12.0m, a ring width of 0.625m, and a thickness of 0.2m. The segmentation method is the same as that of closed ring 2. The assembly method is the same as the implementation method described above.

[0052] In summary, the embodiments of the present invention provide a support structure and its construction method for the tunnel boring machine's diameter expansion process, which has the following advantages: 1) Solving the problem of support for the open face and ensuring construction safety: This invention achieves immediate closure and support of the open face 10 of the soil after the diameter change and expansion by setting a closed ring 2 between the cutterhead 11 and the shield body 12 and a support ring 5 that extends with the excavation. This effectively prevents the surrounding rock 13 from collapsing, falling off, and becoming unstable and deformed, filling the gap in the existing technology for the lack of effective support methods in the transition section of the diameter change.

[0053] 2) Adaptable to confined spaces, enabling unmanned and rapid assembly: The support components adopt a lightweight modular design, perfectly adapting to the narrow and complex working space behind the cutterhead 11; the innovative use of limit connectors with radial through-cutting and interlocking axial x-sliding between segments eliminates the traditional bolt connection, allowing for fully automatic and efficient gripping and locking by a robotic arm without the need for manual entry into the chamber, significantly reducing the risk of personnel operation.

[0054] 3) Strong structural integrity and good synergistic stress effect: The radial snap-fit ​​structure provides strong circumferential constraint force to prevent the segment unit from separating; combined with the grouting process of the axial x and radial anchor rods 7, the closed ring 2 is anchored to the diameter expansion step and the support ring 5 is rooted in the stable rock layer, thus constructing an integrated bearing system of segment-surrounding rock 13, which effectively controls the deformation of the strata.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A support structure for use in the diameter expansion process of a tunnel boring machine, characterized in that, include: The tunnel boring machine (TBM) includes a limiting connector and multiple closed segment units. The multiple closed segment units are connected end to end in the circumferential direction to form a closed ring. The limiting connector is radially inserted between two adjacent closed segment units and is respectively engaged with two adjacent closed segment units. The closed ring is used to be sleeved on the outer periphery of the shield body of the TBM and is located behind the cutterhead of the TBM in the axial direction. The closed ring has a support surface that is axially away from the shield body of the TBM and abuts against the soil. It also includes multiple support segment units, which are connected end to end in the circumferential direction to form a support ring. Adjacent support segment units are interlocked. The support ring is used to be fitted on the shield body. One axial end of the support ring is connected to the side of the closed ring that is axially away from the support surface. The outer peripheral wall of the support ring is used to abut against the soil. The closed tube segment unit has a first side and a second side arranged opposite to each other in the circumferential direction. The first side has a first snap-fit ​​groove that extends axially and is at least unidirectionally through. The second side has a first sliding snap-fit ​​part that extends axially. The first snap-fit ​​groove and the first sliding snap-fit ​​part are slidably connected to realize the limiting connection of two adjacent closed tube segment units. The closed segment unit has an inner side facing the shield in the radial direction. The first side and the second side are each provided with a second snap-fit ​​groove extending in the radial direction. The second snap-fit ​​groove extends unidirectionally to the inner side. The limiting connector is provided with a second sliding snap-fit ​​part on each of its opposite sides. The limiting connector passes through the second snap-fit ​​groove from the inner side through the second sliding snap-fit ​​part and snaps with the closed segment unit.

2. The support structure for the tunnel boring machine diameter expansion process as described in claim 1, characterized in that, It also includes anchor bolts, wherein the closed segment unit has axially penetrating anchor bolt holes, and / or the support segment unit has radially penetrating anchor bolt holes; the anchor bolts pass through the anchor bolt holes and connect with the soil.

3. The support structure for the tunnel boring machine diameter expansion process as described in claim 1, characterized in that, The support segment unit has two connecting sides arranged opposite each other in the circumferential direction. A third snap-fit ​​groove extending axially and passing through one direction is provided on the connecting side. A third sliding snap-fit ​​part extending axially is also provided on the connecting side. The third sliding snap-fit ​​part and the third snap-fit ​​groove are arranged opposite each other in the axial direction. Two adjacent support segment units are snapped together by the third sliding snap-fit ​​part and the third snap-fit ​​groove.

4. The support structure for the tunnel boring machine diameter expansion process as described in claim 1, characterized in that, It also includes a fixing connector. The closed segment unit has a first fixing connection hole on the side facing away from the support surface in the axial direction. The support segment unit has the fixing connector on the side facing the closing ring in the axial direction. The fixing connector passes through the first fixing connection hole to connect the support segment unit and the closed segment unit.

5. The support structure for the tunnel boring machine diameter expansion process as described in claim 4, characterized in that, It includes multiple support rings, which are connected sequentially along the axial direction. The closed segment unit has a second fixed connection hole on the side facing away from the closed ring in the axial direction. Adjacent support rings are connected by the fixed connector and the second fixed connection hole.

6. The support structure for the tunnel boring machine diameter expansion process as described in claim 1, characterized in that, The first snap-fit ​​groove has a limiting groove extending along the extension direction of the first snap-fit ​​groove on its groove wall, and the first sliding snap-fit ​​part has a limiting part extending along the extension direction of the first sliding snap-fit ​​part protruding on its groove, and the limiting part is limited and engaged with the limiting groove.

7. A construction method for a support structure used in the tunnel boring machine's diameter expansion process, for the support structure as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1 cutterhead expansion: When the variable diameter shield machine excavates to the preset expansion point, the cutterhead is controlled to perform radial rock breaking and expansion excavation until the cutterhead diameter reaches the designed expansion diameter; S2 creates working space: After the cutterhead is enlarged, the tunnel boring machine is controlled to advance forward a preset distance, leaving working space between the cutterhead and the shield body; S3 Installation of the closed ring: The closed segment unit is transported to the working space, and the robotic arm on the tunnel boring machine is used to grab and install the closed segment unit piece by piece. After each pair of adjacent closed segment units are assembled in place, a limiting connector is inserted at the connection point for fixation until the installation of the entire closed ring is completed. S4 Closed Ring Anchoring Grouting: After the closed ring is installed, anchor bolts are driven into the surrounding rock axially through the anchor bolt holes on the closed segment unit, and grouting is performed; S5 Installing the support ring: Control the tunnel boring machine to advance a support ring axial distance, transport the support segment unit to the work space, and use a robotic arm to grab and install the support segment unit piece by piece; S6 Support Ring Anchoring Grouting: After the support ring is installed, anchor bolts are driven radially into the surrounding rock through the anchor bolt holes on the support segment unit, and grouting is performed; S7 Cycle Construction: Control the tunnel boring machine to continue tunneling forward, repeating S5 and S6 until the construction of the subsequent support structure is completed.

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