A whole starting method of subway shield single well

Abstract

The application discloses a subway shield single-well integral launching method, which comprises the following steps: hole door installation and re-measurement, track laying, launching base installation, shield hoisting assembly, counterforce frame installation, hole door sealing installation, horizontal hole drilling, hole door removal, negative ring segment assembly, shield trial tunneling, negative ring, launching bracket and counterforce frame removal. The application utilizes the existing temporary facilities and infrastructures on the construction site, meets the requirements of civilized construction and safety production, has the advantages of simple construction process, high construction efficiency, neat and beautiful site, convenient material and slag transportation and high safety.

Description

Technical Field

[0001] This invention relates to the field of shield tunneling technology, and more specifically to a method for the overall launching of a single shaft of a subway shield tunnel. Background Technology

[0002] With the acceleration of urbanization in China, more and more cities are choosing to alleviate urban traffic congestion by building underground transportation systems. Subway transportation is a green project; its development is a necessity for urban development and an inevitable trend in the future development of underground resources.

[0003] Due to the complex urban terrain and surrounding buildings, the tunnel boring machine (TBM) method was required for subway construction. However, given the limited construction site, the TBM launching shaft was designed as a single shaft. This single-shaft, multi-unit launching scheme suffers from drawbacks such as cumbersome construction procedures, extremely low construction efficiency, and high investment costs.

[0004] Therefore, there is an urgent need for a method for the overall launching of a single shaft for subway tunnel boring machines. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for the overall launching of a single shaft of a subway shield tunnel, so as to solve the problems in the background art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows.

[0007] A method for the overall launching of a single shaft of a subway tunnel boring machine includes the following steps:

[0008] S1. Portal installation and re-measurement: The portal steel ring is made of four equal blocks welded together at 90° arcs. First, install the lower half of the steel ring. After the lower half of the inner lining wall reinforced concrete construction is completed, install the upper half of the ring. Finally, re-measure the portal installation.

[0009] S2. Track laying in the mined tunnel: Installation and laying of the supporting running track and battery vehicle running track after shield tunneling in the mined tunnel.

[0010] S3. Installation of the launching base: During installation, the elevation of the launching base is controlled so that the front end is 20mm higher than the rear end, and the center elevation of the tunnel boring machine is consistent with the center elevation of the launching portal.

[0011] S4. Shield hoisting and assembly: The trolley, equipment bridge, and spiral conveyor are pre-stored in the shaft, and then the middle shield, front shield, cutterhead, assembly machine, and tail shield are installed in sequence.

[0012] S5. Reaction Frame Installation: The reaction frame is processed in sections and assembled on site to ensure that it is perpendicular to the central axis of the tunnel boring machine.

[0013] S6. Install the tunnel portal seal: A circular ring plate is pre-embedded at the starting tunnel entrance, with pre-drilled fixing screw holes on the circular ring plate. The curtain rubber sheet is fixed to the steel ring at the tunnel entrance by pressure plate and bolts.

[0014] S7. Horizontal Exploration Hole: To detect the water level of the end dewatering well. After the water level drops to 1m below the tunnel bottom, and before the tunnel portal retaining structure is removed, a horizontal exploration hole is drilled to detect the amount of water used to break the tunnel portal and the reinforcement effect.

[0015] S8. Tunnel Portal Removal: Erect a platform, cover it with thick wooden planks, set up a fence around the platform and hang a safety net; break through layer by layer from top to bottom and cut off the outer steel bars, cut off the steel bars on the back side of the soil with gas cutting, tie up the cut waste steel bars and lift them out of the shield shaft, and at the same time clean up the slag.

[0016] S9. Assemble the negative ring segments: First, fill the shield tail sealing grease into the shield tail wire brush, and separate the wire brush. The stainless steel mesh in the middle of the wire brush and the wire brush should be fully filled. Calculate the number of negative rings and assemble them. Drive wooden wedges into the gap between the starting bracket guide rail and the outer diameter of the negative ring to support the negative ring.

[0017] S10. Shield tunneling trial excavation: A guide rail is set between the launching bracket and the tunnel portal along the direction of the launching guide rail. The elevation of the guide rail should be 1-2cm higher than the elevation of the bracket rail. At the initial stage of the cutterhead contacting the working face, the screw conveyor discharge gate is closed in advance. When the soil chamber is 2 / 3 full of excavated soil, the screw conveyor is gradually started and the discharge gate is opened to discharge soil. During the tunneling process, the actual amount of soil discharged is continuously compared with the theoretical amount of soil discharged, and the attitude of the shield machine is monitored and adjusted in real time.

[0018] S11, Negative Ring, Launching Bracket, and Reaction Frame Removal: After the tunnel boring machine has completed 100 meters of trial excavation, the negative ring segments, reaction frame, and launching bracket are removed. The switch is then replaced and laid. The air duct storage bracket at the rear of the trolley is installed, and ventilation inside the tunnel begins. Preparations for formal tunneling are completed, and the launching site layout is restored to normal construction status.

[0019] To further optimize the technical solution, in step S3, after the launching base is installed, it is supported in the front, back, left and right to achieve reinforcement. Two 20a I-beams are used to support the front and rear ends to the portal end wall and the reaction frame base. 20a I-beams are used to support the left and right sides to the launching shaft side wall and the upper beam concrete. Then the launching base connecting bolts are tightened again.

[0020] To further optimize the technical solution, in step S4, the number of trolleys is five, the trolleys are lowered into the shaft in reverse order, and each trolley section is immediately pulled into the tunnel by a battery-powered vehicle to provide a position for the next trolley section. When the equipment bridge and screw conveyor are pre-stored in the tunnel, they are reinforced with hoists until the shield body is hoisted and spliced ​​before installation and connection.

[0021] To further optimize the technical solution, in step S5, the center lines of the reaction frame, the bracket, and the tunnel are made to coincide, and the verticality of the reaction frame is controlled within 2‰ and less than 10mm. Two double-limb 20a I-beams are used for top support and reinforcement behind the columns on both sides of the reaction frame. Four double-limb 20a I-beams are used for top support and reinforcement on the bottom crossbeam of the reaction frame. Four double-limb 20a I-beams are used for welded top support and reinforcement behind the top crossbeam.

[0022] To further optimize the technical solution, the installation of the tunnel portal seal in step S6 is carried out in two steps. The first step is to carry out the embedding of the steel ring of the tunnel portal during the construction of the launching shaft structure, and connect the embedded part with the steel reinforcement of the launching shaft structure. The second step is to clean up the slag at the tunnel entrance before the shield tunneling machine is officially launched, and clean the threaded holes of the ring plate with steel wire before installation and apply grease.

[0023] To further optimize the technical solution, in step S7, the depth of the horizontal borehole should not be less than 3m and the diameter should be 80mm. The borehole should be located at the edge of the shield tunnel. If water seepage occurs, it should be sealed with wooden plugs and cotton yarn. Then, boreholes should be drilled on the ground at the end and vertically at the tunnel entrance. The end should be reinforced by compaction grouting.

[0024] Due to the adoption of the above technical solutions, the technical progress achieved by this invention is as follows.

[0025] This invention provides a method for the overall launching of a single shaft for a subway tunnel boring machine (TBM). During construction, adjustments are made to ensure the TBM's performance is optimal, tunneling parameters are strictly controlled to ensure uniform, balanced, and continuous passage, ground loss rate is strictly controlled, working face pressure is kept stable, and disturbance to the ground is minimized to reduce settlement. Grouting is used to fill the voids formed after the shield tail separates, creating a waterproof layer on the outside of the tunnel segments, improving the tunnel's waterproofing effect, ensuring segment stability, preventing segment floating, lateral displacement, and misalignment, and also controlling surface settlement. This invention utilizes existing temporary facilities and infrastructure at the construction site; meets the requirements of civilized construction and safe production; and has the advantages of simple construction procedures, high construction efficiency, a clean and aesthetically pleasing site, convenient material and excavation transportation, and high safety. Attached Figure Description

[0026] Figure 1 This is a flowchart of the present invention;

[0027] Figure 2 This is a schematic diagram of the initial base support and reinforcement structure in this invention;

[0028] Among them: 1. reaction frame, 2. 20a I-beam. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] A method for the overall launching of a single shaft for subway tunnel boring machines, combined with Figures 1 to 2 As shown, it includes the following steps:

[0031] S1. Tunnel Portal Installation and Re-measurement: The tunnel portal steel ring is constructed by welding four equal blocks together at 90° arcs. Anchor bars are installed on the outer side and edges of the steel ring and welded to the inner lining wall reinforcement. The inner lining wall at the end shaft must be constructed using segmented and layered pouring. Therefore, the installation of the shield tunnel steel ring must be carried out in two stages. First, the lower half of the steel ring is installed. After the lower half of the inner lining wall reinforced concrete construction is completed, the upper half of the ring is installed. Finally, the tunnel portal installation is re-measured.

[0032] The installation process is as follows: measuring and positioning the center of the tunnel portal, measuring and positioning the outline of the steel ring, welding the triangular positioning steel plate on the retaining structure, assembling and positioning the lower half of the steel ring in the well, measuring and verifying the inspection, welding the joint of the two steel rings in the lower half of the ring, constructing the inner lining wall of the lower half, assembling and positioning the upper half of the steel ring in the well, measuring and verifying the entire ring, welding and connecting the joints of the upper and lower half rings, and completing the installation.

[0033] S2. Track Laying in the Cut-and-Cut Tunnel: The installation and laying of the supporting running tracks and battery-powered vehicle tracks are carried out inside the cut-and-cut tunnel. 43kg / m steel rails are used, and the rails are connected by rail clamps. Flat steel is used as sleepers under the rails, and standard fasteners are used to fix the rails and sleepers together.

[0034] S3. Launching Base Installation: During installation, the elevation of the launching base is controlled so that the front end is 20mm higher than the rear end, and the center elevation of the tunnel boring machine (TBM) is consistent with the center elevation of the launching portal. During TBM launch, the launching base bears longitudinal and lateral reaction forces. Anti-torsion blocks are welded to the shield body to constrain the shield's torque. After installation, the launching base is reinforced by front, rear, left, and right supports. Two 20A H-beams are used to support the front and rear ends to the portal end wall and the reaction frame base. 20A H-beams are used on the left and right sides to support the side walls of the launching shaft and the upper beam concrete. The connecting bolts of the launching base are then retightened to ensure rigidity requirements.

[0035] S4. Shield Installation and Assembly: The trolleys, equipment bridges, and augers are pre-stored in the shaft. Then, the middle shield, front shield, cutterhead, assembly machine, and tail shield are sequentially lowered and installed. The five trolleys are lowered in reverse order: 5#--4#--3#--2#--1#. Each trolley section is immediately transported to the tunnel using a battery-powered vehicle to provide space for the next section. The equipment bridges and augers are reinforced with hoists during pre-storage in the tunnel until the shield installation and splicing are completed. The main control point during shield installation is the lowering error of the middle shield, ensuring that the horizontal and vertical error between the centerline of the middle shield and the tunnel centerline is within 5mm. Subsequent lowered shields only need to be spliced ​​and moved with the middle shield.

[0036] S5. Reaction Frame Installation: The reaction frame is fabricated in sections and assembled on-site to ensure it is perpendicular to the center axis of the tunnel boring machine; the center lines of the reaction frame, the bracket, and the tunnel are aligned, and the verticality of the reaction frame is controlled within 2‰ and 10mm; two double-limb 20a I-beams are used for top support and reinforcement behind the columns on both sides of the reaction frame; four double-limb 20a I-beams are used for top support and reinforcement on the bottom crossbeam of the reaction frame; four double-limb 20a I-beams are welded and reinforced behind the top crossbeam.

[0037] During installation, with the cooperation of the surveying team, the reaction frame was precisely positioned to ensure it was perpendicular to the central axis of the tunnel boring machine (TBM). During installation, the lateral deviation of the reaction frame was controlled within ±10mm, the elevation deviation within ±5mm, and the vertical deviation within ±10mm. The angle between the vertical direction of the launch platform's horizontal axis and the reaction frame was <±2%, the vertical deviation of the TBM's attitude from the design axis was <±2%, and the horizontal deviation was <±3%.

[0038] S6. Installation of Tunnel Portal Seal: A circular ring plate is pre-embedded at the tunnel entrance, with pre-drilled fixing bolt holes. The rubber curtain sheet is fixed to the steel ring at the tunnel entrance using pressure plates and bolts. This is to prevent soil erosion during tunnel boring machine (TBM) launch, which could affect the establishment of soil pressure and the stability of the excavation face, and to prevent soil erosion at the tunnel portal during TBM launch, thus ensuring grouting effectiveness and the safe and smooth operation of the TBM launch.

[0039] The installation of the tunnel portal seal is carried out in two steps. The first step is to embed the steel ring of the tunnel portal during the construction of the launching shaft structure, and connect the embedded part with the steel reinforcement of the launching shaft structure. The second step is to clean up the slag at the tunnel entrance before the tunnel boring machine is officially launched. Before installation, the threaded holes of the ring plate are cleaned with steel wire and grease is applied.

[0040] During the initial launch of the tunnel boring machine (TBM), the machine head should be kept as concentric as possible with the tunnel entrance or slightly raised. At the same time, there should be no protrusions on the surface of the TBM shell to avoid tearing the fabric rubber sheet. The surface of the machine head shell and ring plate should be coated with grease to facilitate the TBM's smooth passage.

[0041] S7. Horizontal Exploration Holes: To check the water level in the dewatering wells at the tunnel end, and after the water level drops to 1m below the tunnel bottom, horizontal exploration holes are drilled before the tunnel portal retaining structure is removed. These holes are used to check the water volume and reinforcement effect during the removal of the portal. The depth of the horizontal exploration holes should be no less than 3m and the diameter should be 80mm. The holes should be located at the edge of the shield tunneling area. If water seepage occurs, wooden plugs and cotton yarn should be used to seal the holes to ensure that there is no groundwater during the initial operation. Then, boreholes are drilled on the ground at the tunnel end and vertically at the tunnel portal. Compaction grouting is used to reinforce the tunnel end until the soil reinforcement effect meets the design requirements. Then, horizontal exploration holes are drilled again to check the reinforcement effect.

[0042] S8. Tunnel Portal Removal: Construct a platform for tunnel portal removal, covering it with thick wooden planks. Set up a fence around the platform and install safety netting. The portal removal proceeds layer by layer from top to bottom, cutting off the outer reinforcing bars and using gas cutting to remove the reinforcing bars on the back side of the tunnel. The cut waste reinforcing bars are bundled and hoisted out of the shield shaft, while simultaneously clearing away the debris. After the outer pile body is removed and cleared, the area between the piles is probed to ensure there is no risk of water or sand inrush. The second step is to remove the inner pile concrete, preserving the reinforcing bars as a last line of defense in case of water or sand inrush, thus minimizing risk. After clearing away the debris, the reinforcing bars are cut.

[0043] S9. Assemble the negative ring segments: First, fill the shield tail wire brush with shield tail sealing grease, and separate the wire brushes. Ensure the stainless steel mesh in the middle of the wire brush and the wire brush itself are fully filled. Calculate the number of negative rings and assemble them. The negative rings use precast reinforced concrete segments. Considering assembly accuracy and precise installation points, standard ring through-joint assembly is selected to ensure the cylinder stroke is within 40mm.

[0044] When assembling the first negative ring segment, since the upper segment is unrestrained, to prevent instability between adjacent segments, an "L"-shaped steel plate can be welded between the shield shell and the negative ring segment before the segment assembly machine returns to its position to stabilize the segment. After the segment is pulled out of the shield tail, it should be restrained with steel wire rope in time to avoid large deformation. To ensure the shield tail clearance, four steel strips are placed at the shield tail, with angle steel at both ends for stabilization. These strips can be removed after the second ring is assembled.

[0045] When the tunnel segment detaches from the shield shell, wooden wedges are driven into the gap between the starting bracket guide rail and the outer diameter of the negative ring to support the negative ring.

[0046] S10. Shield Tunneling Trial Excavation: A guide rail is installed between the launching bracket and the tunnel portal along the direction of the launching guide rail. The elevation of the guide rail should be 1-2 cm higher than the elevation of the bracket rail. During the initial contact of the cutterhead with the working face at launch, the auger conveyor's discharge gate is closed beforehand. When the soil chamber is 2 / 3 full, the auger conveyor is gradually started, and the discharge gate is opened to discharge soil. During the tunneling process, the actual amount of soil discharged is continuously compared with the theoretical amount. Real-time monitoring and adjustment of the shield machine's attitude are conducted to maintain a basically balanced thrust of the shield machine's propulsion cylinders, ensuring that the displacement of the cutterhead center and the shield tail center is within the allowable deviation range. Corrective measures should be used as little as possible during the initial excavation stage.

[0047] During tunneling in the reinforced area, grouting is performed simultaneously behind the tunnel segments to quickly and reliably fill the gaps behind the segments, preventing ground disturbance and collapse that could lead to surface subsidence. As the number of segment rings increases, the grouting pressure can be gradually increased to ensure that the upper gaps behind the segments are also filled with grout. In earth pressure balance sections, the grouting pressure at the shield tail should be slightly higher than the pressure at the top of the earth chamber. The grouting volume is determined based on the grouting pressure and the amount of slag removed. If necessary, a double-liquid grout is injected through a pipe at the tunnel portal to seal any leaks. After the tunnel boring machine (TBM) has excavated to the final ring, the shield tail is removed from the reinforced body, and a second grouting is performed on the middle ring of the shield tail using a double-liquid grout. The initial setting time of the grout is 2 to 3 minutes. As much grout as possible is injected to seal the gaps between the segments and the rear section, preventing groundwater from returning to the tunnel portal. The grouting pressure is controlled below 0.3 MPa.

[0048] S11, Negative Ring, Launching Bracket, and Reaction Frame Removal: After the tunnel boring machine has completed 100 meters of trial excavation, the negative ring segments, reaction frame, and launching bracket are removed. The switch is then replaced and laid. The air duct storage bracket at the rear of the trolley is installed, and ventilation inside the tunnel begins. Preparations for formal tunneling are completed, and the launching site layout is restored to normal construction status.

[0049] The task content and process are as follows:

[0050] (1) Remove the rear steel support of the reaction frame and the diagonal brace of the reaction frame, remove the connecting bolts between the steel ring of the reaction frame and the negative ring segment, release the stress between the negative ring segments, and prepare to remove the negative ring segments.

[0051] (2) The dismantling of the negative ring segments is carried out by segmented lifting, and the lifting operation is completed by a 50-ton gantry crane. Each negative ring segment is lifted in sequence. After the lifting is completed, the rails and sleepers on the launching bracket are removed, the connection between the launching bracket and the base plate is removed, and the launching bracket is lifted.

[0052] (3) After the initial support is lifted, the reaction support is lifted.

[0053] (4) Remove debris from the bottom plate, lay sleepers, install turnouts, and resume construction to proceed with normal tunneling.

Claims

1. A method for launching a whole subway shield single shaft, characterized in that, Specifically, the following steps are included: S1. Portal installation and re-measurement: The portal steel ring is made of four equal blocks welded together at 90° arcs. First, install the lower half of the steel ring. After the lower half of the inner lining wall reinforced concrete construction is completed, install the upper half of the ring. Finally, re-measure the portal installation. S2. Track laying in the mined tunnel: Installation and laying of the supporting running track and battery vehicle running track after shield tunneling in the mined tunnel. S3. Installation of the launching base: During installation, the elevation of the launching base shall be controlled so that the front end is 20mm higher than the rear end, and the center elevation of the tunnel boring machine is consistent with the center elevation of the launching portal. S4. Shield hoisting and assembly: The trolley, equipment bridge, and spiral conveyor are pre-stored in the shaft, and then the middle shield, front shield, cutterhead, assembly machine, and tail shield are installed in sequence. S5. Reaction Frame Installation: The reaction frame is processed in sections and assembled on site to ensure that it is perpendicular to the central axis of the tunnel boring machine. S6. Install the tunnel portal seal: A circular ring plate is pre-embedded at the starting tunnel entrance, with pre-drilled fixing screw holes on the circular ring plate. The curtain rubber plate is fixed to the steel ring at the tunnel entrance by pressure plate and bolts. S7. Horizontal Exploration Hole: To detect the water level of the dewatering well at the end. After the water level drops to 1m below the tunnel bottom, and before the tunnel portal retaining structure is removed, a horizontal exploration hole is drilled to detect the amount of water used to break the tunnel portal and the reinforcement effect. S8. Tunnel Portal Removal: Erect a platform, cover it with thick wooden planks, set up a fence around the platform and hang a safety net; break through layer by layer from top to bottom and cut off the outer steel bars, cut off the steel bars on the back side of the soil with gas cutting, tie up the cut waste steel bars and lift them out of the shield shaft, and at the same time clean up the slag. S9. Assemble the negative ring segments: First, fill the shield tail sealing grease into the shield tail wire brush, and separate the wire brush. The stainless steel mesh in the middle of the wire brush and the wire brush should be fully filled. Calculate the number of negative rings and assemble them. Drive wooden wedges into the gap between the starting bracket guide rail and the outer diameter of the negative ring to support the negative ring. S10. Shield tunneling trial excavation: A guide rail is set between the launching bracket and the tunnel portal along the direction of the launching guide rail. The elevation of the guide rail should be 1-2cm higher than the elevation of the bracket rail. At the initial stage of the cutterhead contacting the working face, the screw conveyor discharge gate is closed in advance. When the soil chamber is 2 / 3 full of excavated soil, the screw conveyor is gradually started and the discharge gate is opened to discharge soil. During the tunneling process, the actual amount of soil discharged is continuously compared with the theoretical amount of soil discharged, and the attitude of the shield machine is monitored and adjusted in real time. S11, Negative Ring, Launching Bracket, and Reaction Frame Removal: After the tunnel boring machine has completed 100 meters of trial excavation, the negative ring segments, reaction frame, and launching bracket are removed. The switch is then replaced and laid. The air duct storage bracket at the rear of the trolley is installed, and ventilation inside the tunnel begins. Preparations for formal tunneling are completed, and the launching site layout is restored to normal construction status.

2. The method for integral launching of a single shaft of a subway shield tunnel according to claim 1, characterized in that: In step S3, after the launching base is installed, it is supported in the front, back, left and right to achieve reinforcement. Two 20a I-beams are used to support the front and rear ends to the portal end wall and the reaction frame base. 20a I-beams are used to support the left and right sides to the launching shaft side wall and the upper beam concrete. Then the launching base connecting bolts are tightened again.

3. The method for integral launching of a single shaft of a subway shield tunnel according to claim 2, characterized in that: In step S4, there are five trolleys. The trolleys are lowered into the shaft in reverse order. Each trolley section is immediately pulled into the tunnel by a battery-powered vehicle to provide a position for the next trolley section. When the equipment bridge and screw conveyor are pre-stored in the tunnel, they are reinforced with hoists until the shield body is hoisted and spliced ​​before installation and connection.

4. The method for integral launching of a single shaft of a subway shield tunnel according to claim 3, characterized in that: In step S5, the center lines of the reaction frame, the bracket, and the tunnel are aligned to ensure the verticality of the reaction frame is controlled within 2‰ and less than 10mm. Two double-limb 20a I-beams are used for top support and reinforcement behind the columns on both sides of the reaction frame. Four double-limb 20a I-beams are used for top support and reinforcement on the bottom crossbeam of the reaction frame. Four double-limb 20a I-beams are welded and reinforced behind the top crossbeam.

5. The method for integral launching of a single shaft of a subway shield tunnel according to claim 4, characterized in that: The installation of the tunnel portal seal in step S6 is carried out in two steps. The first step is to lay the steel ring of the tunnel portal during the construction of the launching shaft structure, and connect the embedded part with the steel reinforcement of the launching shaft structure. The second step is to clean the slag at the tunnel entrance before the shield tunneling machine is officially launched. Before installation, the threaded holes of the ring plate are cleaned with steel wire and grease is applied.

6. The method for integral launching of a single shaft of a subway shield tunnel according to claim 1, characterized in that: In step S7, the depth of the horizontal borehole should not be less than 3m and the diameter should be 80mm. The borehole should be located at the edge of the shield tunnel. If water seepage occurs, it should be sealed with wooden plugs and cotton yarn. Then, boreholes should be drilled on the ground at the end and vertically at the tunnel entrance. The end should be reinforced by compaction grouting.

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