TBM (Tunnel Boring Machine) withdrawing process method

Abstract

The invention relates to a TBM (Tunnel Boring Machine) withdrawing process method, which comprises the following steps of: 1, separating a main machine from a trolley set, and driving the trolley set to withdraw; secondly, roadway maintenance is conducted in a neutral area between the tail of the main engine and the first section of trolley of the trolley set, and the roadway maintenance comprises slope expanding, bottom lifting and waste rock discharging; step 3, driving the host to return; and fourthly, the first step, the second step and the third step are circulated till the TBM moves backwards to the starting installation position. According to the TBM withdrawing process method for alternating withdrawing of the trolley set and the main machine, the withdrawing process method is simple, reliable and high in safety coefficient.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel boring machines, and in particular to a TBM (Tunnel Boring Machine) withdrawal process. Background Art

[0002] With the continuous advancement of coal mining technology, the application of full-face tunnel boring machines (TBMs) in coal mine rock tunnel excavation is becoming increasingly mature. However, after tunnel construction is completed or during tunneling, TBM withdrawal faces many challenges. Currently, TBM withdrawal mainly involves two methods: in-situ dismantling and retreating to the installation chamber. In-situ dismantling requires the construction of a dismantling chamber around the TBM main body, which is time-consuming and highly risky. Retreating to the installation chamber requires expanding the excavated tunnel wall and digging the bottom, which is labor-intensive. Summary of the Invention

[0003] In view of this, the present invention provides a TBM retraction process method, thereby solving or alleviating one or more of the above-mentioned problems and other problems existing in the prior art.

[0004] In order to achieve the aforementioned object, the present invention provides a TBM retraction process method, wherein the process method comprises the following steps: The first step is to separate the main machine and the trolley group, and drive the trolley group back; The second step is to perform tunnel maintenance in the gap area between the tail of the main engine and the first trolley of the trolley group, including expanding the sidewall, lifting the bottom and removing the waste rock; The third step is to drive the host to roll back; Step 4: Repeat steps 1 to 3 until the TBM moves back to the starting installation position.

[0005] In the process method described above, optionally, the step of driving the trolley assembly to retreat in the first step includes: A rear pallet is fixedly arranged on the side wall of the lane behind the last trolley of the trolley group, and the rear pallet is connected to the last trolley by a chain and a retraction cylinder, and the trolley group is driven to move backward by the contraction of the retraction cylinder.

[0006] In the process method described above, optionally, the rear pallet is arranged symmetrically along the central symmetry plane of the aisle, and the chain includes a first chain connecting the retraction cylinder and the last trolley and a second chain connecting the retraction cylinder and the rear pallet. When the first chain and the second chain are tensioned, the retraction cylinder is in a suspended state.

[0007] In the process method as described above, optionally, a push-pull cylinder is provided between the main engine and the first trolley, and the first step further comprises removing the push-pull cylinder and moving it to the rear of the trolley group as the retraction cylinder.

[0008] In the process method described above, optionally, in the second step, the expansion width is greater than the outer diameter of the support shield of the main machine, the bottoming depth is determined according to the bottom gap of the main machine, and the waste rock discharge is completed using the belt conveyor inside the trolley group.

[0009] In the process method described above, optionally, the host rollback step in the third step includes: Auxiliary pallets are symmetrically installed on the side walls of the expanded tunnel. The auxiliary pallets are connected to the third chain. The third chain bypasses the frame structure at the tail of the support shield. The main push cylinder of the main machine is connected between the support shield and the front shield and the cutter disc of the main machine. The front shield and the cutter disc are moved backward by the contraction of the main push cylinder.

[0010] In the process method as described above, optionally, after the main push cylinder retracts, it is re-extended to move the support shield backward, and after tightening the third chain, the main machine retraction action is repeated.

[0011] In the process method as described above, optionally, the step distance of the trolley group retreat in the circulation step in the fourth step is consistent with the step distance of the main machine retreat, and the tunnel maintenance is carried out in the gap area formed by the step distance.

[0012] In the process method as described above, optionally, the process method also includes a step of unjamming when the trolley in the trolley group is blocked from retreating: a pneumatic hoist is fixedly installed on the tunnel roof above the blocked trolley to lift the wheels or sliding shoe structure of the trolley upward to eliminate the jam.

[0013] In the process method described above, optionally, the process method also includes a step of unjamming the front shield and the cutter disc of the main machine when they encounter obstruction: an inclined pull tray is set at the top of the tunnel obliquely above and behind the stuck position of the cutter disc, and the inclined pull tray is connected to one end of the inclined pull cylinder, and the other end of the inclined pull cylinder is connected to the fourth chain, and the fourth chain bypasses the conical structure at the rear of the cutter disc, and the inclined pull cylinder is used to pull the cutter disc upward to reduce the friction between its bottom and the bottom surface of the tunnel.

[0014] The present invention designs a TBM retreat process method in which the trolley group and the main machine retreat alternately, so that the TBM retreat process method is simple, reliable and has a high safety factor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The disclosure of the present invention will become more apparent with reference to the accompanying drawings. It should be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the drawings: Figure 1 Schematic diagram of an embodiment of the TBM withdrawal process of the present invention; Figure 2 for Figure 1 A schematic right side view of the tail of the TBM of the embodiment; Figure 3 This is a schematic structural diagram for performing host rollback; Figure 4 This is a schematic right view of the host rollback; Figure 5 It is a flowchart of the TBM retracement method; Figure 6 This is a schematic diagram of the structure in which the top inclined pull cylinder is used to lift the front shield and cutter head to release the jam; Figure 7 for Figure 6 Left side view of the embodiment.

[0016] Figure numerals: 1-main machine; 2-trolley group; 3-first trolley; 4-last trolley; 5-rear pallet; 6-fixed beam; 7-retraction cylinder; 8-first chain; 9-second chain; 10-support shield; 11-auxiliary pallet; 12-third chain; 13-front shield; 14-cutter head; 15-tunnel side wall; 16-oblique pull cylinder; 17-fourth chain; 18-anchor cable; 19-cylinder connecting ear plate. DETAILED DESCRIPTION

[0017] With reference to the accompanying drawings and specific embodiments, the characteristics and advantages of a TBM withdrawal process method of the present invention will be described below in an exemplary manner. However, all descriptions should not be used to form any limitation on the present invention.

[0018] For any single technical feature described or implied in the embodiments mentioned in this document, or any single technical feature shown or implied in the accompanying drawings, the present invention still allows for continued arbitrary combination or deletion between these technical features (or their equivalents) without any technical obstacles, and thus it should be considered that these more embodiments according to the present invention are also within the scope of the description in this document.

[0019] Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the quantity of the technical features indicated. Thus, a feature specified as "first," "second," "third," or "fourth" may explicitly or implicitly include at least one of these features.

[0020] In the description of the present invention, it should be understood that the terms "lateral", "upper", "lower", "top", "inner", "outer", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] Figure 1 Schematic diagram of an embodiment of the TBM withdrawal process of the present invention; Figure 2 for Figure 1 Schematic right side view of the TBM tail of the embodiment.

[0022] In coal mine rock tunnel excavation, the withdrawal of full-face tunnel boring machines (TBMs) has long been hampered by the shortcomings of traditional methods: in-situ disassembly and withdrawal to a designated installation chamber. The existing "disassembly and disassembly" process requires the construction of a disassembly chamber in situ within the tunnel where the TBM is located. Due to the high chamber height requirement, typically exceeding seven meters, this can easily lead to roof collapses, resulting in loss of life and property. Especially in blind tunnel excavation scenarios, the main machine must be disassembled piece by piece from the rear to the head of the TBM, and the components transported back along the existing tunnel. When the rock pressure surrounding the tunnel is high, the existing tunnel will contract radially under the pressure. Even if the main machine is disassembled within the disassembly chamber, some large components cannot be removed from the contracted tunnel, necessitating tunnel expansion, repair, and masonry support, resulting in significant additional work. Furthermore, the construction of a disassembly chamber in a coal mine increases the cross-sectional area and required support strength, significantly increasing construction costs.

[0023] Another withdrawal process - "withdrawing the machine to the installation chamber" has the difficulty that the diameter of the main machine at the head of the TBM is larger than the machine body. If the machine needs to be withdrawn along the original route, the already excavated tunnel needs to be expanded and bottomed out to increase the radial size of the tunnel. However, after the expansion, the support boots on the main machine cannot support the side wall 15 of the tunnel. Therefore, sleepers need to be placed between the main machine support boots and the side wall. Although the sleepers are light in weight, they have low hardness and may reduce the support stability, so sometimes it is necessary to make a wall support fixture. The wall support fixture is a steel structure with high support strength, but it is heavy. In the process of gradually withdrawing the machine, the sleepers or wall support fixtures need to be moved step by step according to the withdrawal process, resulting in high labor intensity for workers, high construction costs and low efficiency.

[0024] The advantages of the machine withdrawal process of the present invention are that, compared with in-situ dismantling, the process of the present invention can avoid excavating and dismantling the chamber at the TBM main machine, thereby improving the safety factor; compared with withdrawing the machine to the installation chamber, the process of the present invention adopts devices and facilities with simpler structure and lighter use, thereby reducing the labor intensity of workers.

[0025] Before introducing the back-off process of the present invention, Figure 1 As shown, the main structure of the TBM includes a main engine 1 and a trolley assembly 2. The main engine is located at the head of the TBM, and the trolley assembly is set behind the main engine. The main engine and the trolley assembly are connected by a push-pull cylinder (not shown). Figure 1 The trolley group is composed of several trolleys connected end to end. The one closest to the main engine is called the first trolley 3, and the one farthest from the main engine is called the last trolley 4. The push-pull cylinder should be connected between the tail end of the main engine and the first trolley. Figure 1 Several trolleys can be connected between the first trolley and the last trolley, and the specific number of trolleys can be adjusted according to working conditions.

[0026] In the TBM retraction process, the first step is to separate the main machine and the trolley group and drive the trolley group back.

[0027] A rear tray 5 can be installed at a certain distance behind the final trolley. Two rear trays can be provided, symmetrically arranged on the tunnel sidewall 15 along the central symmetry plane of the tunnel. Several mounting holes are circumferentially arranged on the rear trays. An anchor cable 18 passes through the mounting holes. One end of the anchor cable can extend into the interior of the tunnel sidewall and be fixedly connected to the rock there. The other end can be fixedly connected to the rear tray via a lock. The number of rear trays can be two or four to distribute stress.

[0028] Figure 2 The chain is not shown in the figure, and the chain is connected between the rear pallet and the last trolley. A retraction cylinder 7 is also provided on the chain, and the chain may include a first chain 8 and a second chain 9. The first chain is used to connect one end of the retraction cylinder 7 and the last trolley, and the second chain 9 is used to connect the other end of the retraction cylinder and the rear pallet. Affected by the gravity of the retraction cylinder, the second chain is in an inclined and drooping state. The first chain 8 is tensioned when the retraction cylinder is shortened, so that it is in a direction close to horizontal with the bottom surface of the tunnel. The first chain set in this direction can minimize the component force in other directions acting on the last trolley, thereby improving energy utilization.

[0029] The retraction cylinder retracts, causing the entire trolley assembly to move backward, with the maximum amount of movement equal to the retraction stroke of the retraction cylinder. Before the trolley assembly moves backward, the rear pallet is positioned a certain distance behind the trolley assembly, a distance that should be several times the retraction stroke. This way, each time the rear pallet is secured, the distance between it and the final trolley is sufficient for the retraction cylinder to complete several retraction strokes. This reduces the number of times the rear pallet needs to be moved and reinstalled, saving labor costs and improving the efficiency of the trolley assembly's rearward movement.

[0030] As the trolley assembly moves backward, the distance between the rear pallet and the last trolley decreases. Each time the retraction cylinder reaches its full stroke, the trolley assembly moves forward and needs to be extended again before the next retraction. To keep the first chain taut, the operator must tighten it. When the retraction cylinder retracts the next time, no stroke is wasted on tensioning the first chain, and the trolley assembly is retracted as far as possible in a single retraction.

[0031] In addition to manually tightening the first chain, a winch drum can also be set at the connection between the first chain and the retraction cylinder, which provides a certain tension by default so that the first chain will not relax. The winch drum can be fixedly connected to the end of the retraction cylinder, so that the first chain can be tightened more sensitively as the retraction cylinder is re-extended, saving reaction time and improving work efficiency. The retraction cylinder can be suspended between the first chain and the second chain. Since its height fluctuates during the process of extension and shortening, non-fixed sleepers can be used for support underneath it. Therefore, the retraction cylinder can adjust its angle according to the real-time force conditions of the chain without being fixed by a limiting device and generating additional stress.

[0032] The retraction cylinder can also be connected directly to the rear pallet via a pull ring at its tail instead of a second chain. The rear pallet can be provided with a multi-degree-of-freedom movable joint with a pin provided thereon, which is used to connect to the pull ring at the tail of the retraction cylinder. In the scheme where both ends of the retraction cylinder are connected by chains, when the first chain is manually tensioned in the telescopic gap of the retraction cylinder, the retraction cylinder has a more obvious pulling and dropping effect on the first and second chains, the tension of the first chain is lower, and more of the retraction stroke of the retraction cylinder is consumed. The design of directly mounting the retraction cylinder on the rear pallet can reduce the shaking of the tail of the retraction cylinder, enhance the structural stability, and better tension the first chain.

[0033] like Figure 2 As shown, the rear section of the final trolley is a frame structure, which can be equipped with fixed beams 6. The fixed beams 6 extend horizontally to both sides of the final trolley, corresponding to the rear trays on the sidewalls of the roadway on both sides. Taking a single fixed beam as an example, the chain passes through the frame structure to bypass the fixed beam and is tightened with a buckle after the first chain is tensioned. During the tensioning of the first chain, the buckle needs to be unfastened, and the first chain needs to be pulled to continue bypassing the fixed beam. After the buckle is tightened, it is refastened.

[0034] Alternatively, the retraction cylinder can be used between the TBM mainframe and the first trolley. During the first step, the mainframe and trolley assembly are separated, requiring the removal of the cylinder between them. The cylinder can then be left idle on the trolley assembly or moved to the rear of the trolley assembly to serve as a retraction cylinder, increasing equipment utilization and saving costs.

[0035] The second step is to carry out tunnel maintenance.

[0036] After the first step is completed, the trolley group has been pulled back as far as possible by the retraction cylinder, creating a certain distance between the tail of the main engine and the first trolley of the group. This distance can be greater than 10 meters. Within this 10-meter space, maintenance work is required. The steps include expanding the wall, raising the bottom, removing the waste rock, and expanding the radial dimension of the roadway to clear the main engine's retraction route.

[0037] The wall expansion process involves excavating the sides of the tunnel using a jackhammer or other construction methods. The walls need to be expanded to a width greater than the outer diameter of the support shield 10. The net cross-sectional width of the expanded tunnel ensures that the main support shoes do not need to contact the wall when the main machine is retracted, allowing the main machine to retract smoothly.

[0038] The tunnel floor can be leveled using a bucket loader or manual labor. The depth of the leveling is determined by the clearance at the bottom of the mainframe, ensuring no risk of the mainframe getting stuck during retraction. Unlike traditional retraction processes, this method only levels the tunnel floor between the trolley and the mainframe, eliminating the need for full tunnel leveling. This reduces the amount of work per operation and reduces the workload for construction personnel.

[0039] Because the trolley group retains a belt conveyor inside, it can serve as the main operating system for waste rock discharge. The waste rock generated by expanding and removing the bottom is directly transported to the temporary waste rock storage area at the rear via a belt conveyor. This design fully utilizes the belt conveyor inside the trolley group, avoiding the need to set up a new conveyor in the tunnel, saving costs and space within the tunnel. The fundamental reason for the implementation of this design is that this maintenance operation and the trolley withdrawal form a streamlined construction: each time the trolley withdraws a certain distance (for example, 10 meters), it completes 10 meters of tunnel maintenance, and the main machine withdraws 10 meters. By gradually withdrawing the trolley group and the main machine in alternating steps, the trolley group is always directly behind the tunnel section that needs to be expanded and removed, eliminating the need to set up additional transportation equipment and improving overall construction efficiency. This gives this solution a significant advantage over withdrawing the entire trolley group from the tunnel at once and then withdrawing the main machine.

[0040] Figure 3 This is a schematic diagram of the structure before the host rollback. Figure 4 This is a schematic right view of the host rollback.

[0041] The third step is to perform host rollback. Figure 3 and Figure 4 A specific implementation method will be described.

[0042] After the second step is completed, a sufficiently spacious lane has been cleared behind the host. First, it is necessary to combine Figure 3The main machine's structure is described below. The front end of the main machine features a cutterhead 14 and a front shield 13, while the rear end features a support shield 10. A main push cylinder (not shown) and main gripper shoes are located between the front shield 13 and the support shield 10. The front end of the main machine is much more massive than the rear end, placing its center of gravity significantly forward. Based on this, the main machine retraction procedure is designed as follows.

[0043] First, at a distance of several meters behind the main support shield, four auxiliary pallets 11 are symmetrically installed on either side of the expanded tunnel wall, two on each side. These pallets can use the same structure as the rear pallets described above. The auxiliary pallets 11 are secured to the tunnel wall via anchor cables 18, using the same method as the auxiliary pallets behind the trolley assembly, which will not be further described. The front and rear auxiliary pallets on the same tunnel wall are spaced a certain distance apart along the tunnel axis, forming bilaterally symmetrical traction anchor points.

[0044] The third chain 12 is used to bypass the cylinder connection lugs 19 behind the support shield, but other structural components capable of passing the chain can also be used. The cylinder connection lugs 19 can be symmetrically located on either side of the support shield. The ends of the third chain can be secured to the front and rear auxiliary pallets on the same side, forming a force transmission path from auxiliary pallet to third chain to support shield. The main propulsion cylinder of the main machine serves as the power source. Based on the main machine's inherent structure, one end of the cylinder is connected to the support shield, while the other end is fixedly connected to the front shield 13 and cutterhead 14, forming a traction force transmission path from support shield to main propulsion cylinder to front shield and cutterhead.

[0045] The main machine retraction process is as follows: 1. Activate the main push cylinder to retract. Since the support shield is secured to the tunnel wall by the third chain, the tension generated by the retracting cylinder drives the front shield 13 and cutterhead 14 backwards. The distance of a single retraction is determined by the retraction stroke of the main push cylinder. 2. After the main push cylinder is fully retracted, the cutterhead and front shield move backward a certain distance. At this point, the piston rod extends forward. Due to the weight difference between the front and rear of the main machine, the support shield tends to rise, reducing friction with the tunnel floor and pushing it backwards. At this point, the third chain slackens. The chain is shortened manually or electrically, and the third chain is re-tensioned to prepare for the next main machine retraction. Because the distance between the main machine and the trolley assembly is greater than the retraction stroke of the main push cylinder, multiple main machine retractions are required before the main machine moves in front of the first trolley. To avoid moving the auxiliary pallet backward multiple times during a single retraction cycle, the auxiliary pallet can be anchored near the first trolley.

[0046] Figure 5 It is a flowchart of the TBM retracement method.

[0047] Step 4: Repeat steps 1 to 3 until the withdrawal is complete.

[0048] like Figure 5As shown, the TBM retraction process of the present invention is that, starting from the initial state, the trolley group retracts a certain distance each time, and this distance becomes the step distance in this cycle step. The tunnel maintenance work is carried out in the gap area between the trolley and the main machine, and the main machine then retreats the same step distance. Obviously, the step distance is not the single contraction stroke of the retraction cylinder or the main push cylinder, but the distance the trolley group or the main machine moves backward in one cycle. The retraction of the trolley group and the main machine forms a flow construction until the TBM moves back to the starting installation position. Through this cycle process, the TBM whole machine retraction process has achieved a technological breakthrough in efficiency, low cost and inherent safety, which is particularly suitable for complex geological conditions with high mine pressure and significant tunnel shrinkage, and provides a safe and cost-saving solution for the retraction of coal mine rock tunnel excavation equipment.

[0049] As an alternative embodiment, since the bottom surface of the tunnel is not flat and has uneven surfaces, the trolley may get stuck when the trolley group retreats. When the trolley is retracted and is blocked by potholes caused by uneven road surface or mine pressure, a pneumatic hoist is fixed and suspended on the tunnel wall above the blocked trolley for emergency treatment. For example, one or more pneumatic hoists are fixed to the tunnel roof above the trolley's stuck position through anchor cables. The hoist hooks hook the lifting points of the trolley frame and slowly lift the trolley wheels or sliding shoe structures to a certain height to cross the obstruction. This operation can immediately eliminate the rigid contact between the trolley and the tunnel floor, converting the stuck friction force from static friction to rolling or sliding friction. Combined with the traction of the retraction cylinder, the blocked trolley can be easily pulled away from the stuck area. The pneumatic hoist has explosion-proof properties and is a preferred implementation method for underground coal mine construction scenarios.

[0050] Figure 6 This is a schematic diagram of the structure using the top inclined pull cylinder to lift the front shield and cutter head to release the jam. Figure 7 for Figure 6 Left side view of the embodiment.

[0051] Optionally, when the main engine front shield and cutterhead encounter a jam due to ground bulge or mine pressure, the top inclined pull cylinder can be used to lift the front shield and cutterhead to release the jam. If the main engine front shield and cutterhead encounter an obstacle in their retraction, an inclined pull tray (not shown) can be installed at the top of the tunnel above and behind the cutterhead jam position. Figure 6 and Figure 7), the end of the inclined pull cylinder 16 is hinged to the inclined pull tray. The structure and fixing method of the inclined pull tray can be the same as the rear tray mentioned above, and the connection method of the inclined pull tray and the inclined pull cylinder 16 can be the same as the connection method of the retraction cylinder and the rear tray mentioned above. The two inclined pull cylinders 16 are respectively arranged on both sides of the cutter disc and the front shield. The two ends of the fourth chain 17 are respectively connected to the telescopic ends of the two inclined pull cylinders, and the middle part of the chain passes around the tapered neck of the cutter disc. Since the inclined pull tray is located obliquely above and behind the cutter disc, the two ends of the fourth chain 17 extend toward the oblique upper and rear. When the inclined pull cylinder 16 contracts, the fourth chain will apply upward and backward components of force to the cutter disc, so that the bottom of the cutter disc is out of contact with the tunnel floor, and it can go over the obstacle backward. The cutter disc can be smoothly retracted by cooperating with the retraction of the main push cylinder. Even if the cutter disc does not leave the tunnel floor, it can reduce friction, which helps the cutter disc to go over obstacles.

[0052] The technical scope of the present invention is not limited to the contents of the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical concept of the present invention, and these deformations and modifications should all fall within the scope of the present invention.

Claims

1. A TBM withdrawal process, characterized in that: The process The following steps are involved: The first step is to separate the main machine (1) and the trolley group (2), and drive the trolley group (2) to retreat; The second step is to perform tunnel maintenance in the gap area between the tail of the main engine (1) and the first trolley (3) of the trolley group (2), including expanding the side, lifting the bottom and removing the waste rock; The third step is to drive the host (1) to roll back; Step 4: Repeat steps 1 to 3 until the TBM moves back to the starting installation position.

2. The process according to claim 1, wherein: The step of driving the trolley group (2) back in the first step includes: A rear tray (5) is fixedly arranged on the side wall (15) of the lane behind the last trolley (4) of the trolley group (2), and the rear tray (5) is connected to the last trolley (4) by a chain and a retraction cylinder (7), and the trolley group (2) is driven to move backward by the contraction of the retraction cylinder (7).

3. The process according to claim 2, wherein: The rear pallet (5) is symmetrically arranged along the central symmetry plane of the laneway, and the chain includes a first chain (8) connecting the retraction cylinder (7) and the last trolley (4) and a second chain (9) connecting the retraction cylinder (7) and the rear pallet (5). When the first chain (8) and the second chain (9) are tensioned, the retraction cylinder (7) is in a suspended state.

4. The process according to claim 2, wherein: A push-pull cylinder is provided between the main engine (1) and the first trolley (3), and the first step further comprises removing the push-pull cylinder and moving it to the rear of the trolley group (2) to serve as the retraction cylinder (7).

5. The process according to claim 1, wherein: In the second step, the expanded width is greater than the outer diameter of the support shield (10) of the main machine (1), the bottoming depth is determined according to the bottom gap of the main machine (1), and the gangue discharge is completed by the belt conveyor inside the trolley group (2).

6. The process according to claim 5, wherein: The step of the host (1) rolling back in the third step includes: Auxiliary pallets (11) are symmetrically installed on the side walls (15) of the expanded tunnel. The auxiliary pallets (11) are connected to the third chain (12). The third chain (12) passes around the cylinder connecting ear plate (19) at the tail of the support shield (10). The main push cylinder of the main machine (1) is connected between the support shield (10) and the front shield (13) and the cutter disc (14) of the main machine (1). The front shield (13) and the cutter disc (14) are driven to move backward by the contraction of the main push cylinder.

7. The process according to claim 6, wherein: After the main push cylinder retracts, it re-extends to move the support shield (10) backward, and after tightening the third chain (12), the main machine (1) retracts.

8. The process according to claim 1, wherein: The step distance of the trolley group (2) in the cycle step of the fourth step is consistent with the step distance of the main machine (1), and the lane maintenance is carried out in the gap area formed by the step distance.

9. The process according to claim 1, wherein: The process method also includes a step of unblocking when the trolley in the trolley group (2) is blocked: a pneumatic hoist is fixedly arranged on the top plate of the tunnel above the blocked trolley to lift the wheels or sliding shoe structure of the trolley upward to eliminate the jam.

10. The process according to claim 1, wherein: The process method further includes a step of unblocking the front shield (13) and the cutter disc (14) of the main machine (1) when encountering an obstruction: an inclined pull tray is provided at the top of the tunnel obliquely above and behind the stuck position of the cutter disc (14); the inclined pull tray is connected to one end of an inclined pull cylinder (16); the other end of the inclined pull cylinder (16) is connected to a fourth chain (17); the fourth chain (17) passes around the conical structure at the rear of the cutter disc (14); and the cutter disc (14) is pulled upward by using the inclined pull cylinder (16) to reduce the friction between its bottom and the bottom surface of the tunnel.

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