Construction method for a ventilation shaft constructed after a shield tunnel section

Abstract

The present invention discloses a construction method for a post-construction ventilation shaft in a shield tunnel section, which includes the following steps: driving the retaining structure of the post-excavation ventilation shaft, breaking the retaining structure by the shield machine and assembling shield segments, installing a tensioning assembly with longitudinal tension at the shield inlet and outlet of the ventilation shaft, excavating the foundation pit of the ventilation shaft, and pouring the structure of the construction ventilation shaft. In the present invention, glass fiber reinforced bored piles are arranged at the shield tunnel section crossing, which is convenient for the shield machine to break through and does not affect the normal non-stop tunneling of the shield tunnel section. By assembling the shield segments with continuous joints inside the ventilation shaft structure, it is convenient to remove the segments during the construction of the ventilation shaft. The shield segments can be effectively connected through the strengthened ring beam and longitudinal tensioning channel steel. The present invention can realize the technology of prior tunneling construction in the shield tunnel section and subsequent construction of the main structure of the ventilation shaft in the section, and has the advantages of small cross-influence during construction, small impact on the surrounding environment, alleviating the construction period pressure, being safe and reliable, etc., and can be applied to the shield tunnel section project with an interval ventilation shaft.

Description

Technical Field

[0001] The invention belongs to the field of ventilation shaft construction methods, and in particular relates to a ventilation shaft construction method after a shield section. Background Art

[0002] With the rapid development of urban rail transit, shield tunneling has gradually become the main method for constructing underground tunnels. According to the driving and line setting requirements, when the interval exceeds 1.6km, it is often necessary to set up an interval ventilation shaft in the middle of the interval, and long intervals need to set up 2 or even more interval ventilation shafts to meet the requirements of interval ventilation and smoke exhaust in accidental fire conditions. According to the conventional shield interval ventilation shaft construction process requirements, the interval ventilation shaft is generally constructed first, and after the main structure of the ventilation shaft reaches the design strength, the shield interval completes the corresponding reception and re-starting station-like work in the ventilation shaft.

[0003] Since the interval ventilation shaft is generally constructed by open-cut method, a certain construction site is required to meet the construction needs. In the complex surrounding environment of the city, it is difficult to select an interval ventilation shaft with a suitable location due to the influence of ground buildings (structures), underground municipal pipelines, ground traffic diversion, etc. When the ground demolition and land occupation coordination progress slowly, and the interval main line has to be constructed first due to the construction period constraints, in order to meet the construction period requirements of the subway without affecting the structural safety, it is necessary to study a new type of interval ventilation shaft construction method that can be built above the constructed section, so as to reduce project investment and ensure the safety of the shield section structure. Summary of the invention

[0004] The present invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a construction method for constructing a ventilation shaft behind a shield section.

[0005] The technical solution of the present invention is: a construction method for constructing a ventilation shaft behind a shield section, comprising the following steps:

[0006] ⅰ. Construct the ventilation shaft enclosure structure in the excavation section

[0007] According to the shield section line and the layout requirements of the internal building rooms of the shield section ventilation shaft, the outer contour line of the ventilation shaft structure is arranged to meet the requirements of ventilation shaft use and driving limit. In combination with the geological conditions of the shield section, bored cast-in-place piles are constructed at the outer contour, and the bored cast-in-place piles are evenly distributed to form the ventilation shaft enclosure structure;

[0008] ⅱ. The shield machine removes the surrounding structure and assembles the shield segments

[0009] Adjust the shield machine so that the cutter head cuts and breaks the bored piles on one side of the retaining structure, and then continue to excavate forward. Then the cutter head cuts and breaks the bored piles on the other side of the retaining structure until the cutter head passes through the interval ventilation shaft range and assembles the shield segments.

[0010] ⅲ. Install a tensioning assembly with longitudinal tension at the shield's air inlet and outlet shafts

[0011] Install the tensioning assembly inside the assembled shield segments, and the tensioning assemblies are evenly distributed in a ring inside the shield segments;

[0012] ⅳ. Excavate the foundation pit of the air shaft

[0013] Excavate the soil and erect the foundation pit support system, then remove the shield segments within the scope of the air shaft, and construct the locking foot anchor cables between the bored cast-in-place piles of the air shaft;

[0014] ⅴ. Pour and construct the structure of the air shaft

[0015] Continue to excavate the foundation pit to the position of the structural bottom slab of the air shaft, tie the bottom slab steel bars, pour concrete, then tie the side wall steel bars, erect I-beam gantries on the bottom slab, arrange plywood, main ledger square timbers, secondary ledger square timbers between the gantries and the side walls, set up ring-lock type scaffolding, pour the side wall, middle slab and end wall strengthening ring beams of the air shaft structure, and finally construct the structural top slab and backfill the soil to complete the construction of the entire section air shaft.

[0016] In step ⅰ, the bored cast-in-place piles include glass fiber reinforced plastic bored cast-in-place piles located in the shield passing area and ordinary steel bar bored cast-in-place piles located in the non-shield passing area.

[0017] The glass fiber reinforced plastic bored cast-in-place piles include glass fiber reinforced plastics that are easy to break during the tunneling of the shield machine. The glass fiber reinforced plastics are fixed to the ordinary steel bars in the glass fiber reinforced plastic bored cast-in-place piles through a connection assembly, and the connection assembly includes a U-shaped fastener, a clamping plate, and a nut.

[0018] In step ⅱ, segment staggering assembly is carried out for the segments outside the air shaft scope using shield staggered joint segments, and segment circumferential joint assembly is carried out for the segments within the air shaft scope using shield circumferential joint segments.

[0019] In step ⅳ, excavating the soil and erecting the foundation pit support system includes the following: Excavate the soil within the scope of the air shaft from top to bottom, and timely erect the first concrete support and the second and third steel supports.

[0020] In step ⅳ, specifically removing the shield segments within the scope of the air shaft includes the following: Excavate to 0.5 m above the shield segments, use manual excavation, after the shield segments are exposed, disassemble the circumferential joint segment bolts in the tunnel, break the top wedge-shaped segments, and successively remove the other segments and hoist them out of the air shaft.

[0021] In step ⅳ, specifically constructing the locking foot anchor cables between the bored cast-in-place piles of the air shaft includes the following: After removing the shield segments, drive two rows of locking foot anchor cables on the side walls of the bored cast-in-place piles to ensure the anti-overturning stability of the foundation pit.

[0022] In step ⅴ, grouting steel pipes are reserved at the interface between the ventilation shaft and the shield segment for grouting to seal the gap and prevent water leakage.

[0023] In step ⅲ, the tensioning assembly includes a longitudinal tensioning channel steel. An assembly hole is formed at the bottom of the groove of the longitudinal tensioning channel steel. A mounting hole corresponding to the assembly hole is formed on the inner wall of the shield staggered joint segment. A threaded sleeve is arranged in the mounting hole, and a bolt passes through the assembly hole of the longitudinal tensioning channel steel and is screwed into the threaded sleeve.

[0024] Before removing the shield segment in the ventilation shaft, the bolts between the longitudinal tensioning channel steel and the shield segment outside the ventilation shaft need to be retightened.

[0025] In the present invention, glass fiber reinforced bored piles are arranged at the shield tunnel crossing section, which is convenient for the shield machine to break through and does not affect the normal non-stop tunneling of the shield tunnel. By assembling shield circumferential joint segments in the ventilation shaft structure, it is convenient to take out the segments during the construction of the ventilation shaft. The shield segments can be effectively connected through the strengthened ring beam and the longitudinal tensioning channel steel.

[0026] The present invention can realize the construction technology of prior tunneling in the shield tunnel section and subsequent construction of the main structure of the ventilation shaft in the section. It has the advantages of small cross-influence during construction, small impact on the surrounding environment, slowdown of the construction period pressure, safety and reliability, etc., and can be applied to the shield tunnel project with a ventilation shaft in the section. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the layout diagram of the bored pile in the present invention;

[0028] Figure 2 is the layout diagram of the glass fiber reinforced bored pile in the present invention;

[0029] Figure 3 is the front view of the glass fiber reinforced bored pile in the present invention;

[0030] Figure 4 is the connection schematic diagram of the ordinary steel bar and the glass fiber reinforced bar in the present invention;

[0031] Figure 5 is the front assembly view of the ordinary steel bar and the glass fiber reinforced bar in the present invention;

[0032] Figure 6 is the three-dimensional assembly view of the ordinary steel bar and the glass fiber reinforced bar in the present invention;

[0033] Figure 7 is the side assembly view of the ordinary steel bar and the glass fiber reinforced bar in the present invention;

[0034] Figure 8 is the assembly drawing of the shield circumferential joint segment in the present invention;

[0035] Figure 9is the assembly drawing of the segment with staggered joints in the shield tunneling of the present invention;

[0036] Figure 10 is the installation schematic diagram of the longitudinal tension channel steel in the present invention;

[0037] Figure 11 is the front view of the longitudinal tension channel steel in the present invention;

[0038] Figure 12 is the side view of the longitudinal tension channel steel in the present invention;

[0039] Figure 13 is the assembly drawing of the longitudinal tension channel steel in the present invention;

[0040] Figure 14 is the assembly plan view of the longitudinal tension channel steel in the present invention;

[0041] Figure 15 is the cross-sectional schematic diagram of the ventilation shaft structure in the present invention;

[0042] Figure 16 is the longitudinal-sectional schematic diagram of the ventilation shaft structure in the present invention;

[0043] Figure 17 is the installation schematic diagram of the strengthening ring beam in the present invention;

[0044] Figure 18 is the installation schematic diagram of the grouting steel pipe in the present invention;

[0045] Figure 19 is the installation schematic diagram of the I-beam portal frame in the present invention;

[0046] Wherein:

[0047] 1 Segment with staggered joints in shield tunneling 2 Segment with circumferential joints in shield tunneling

[0048] 3 Ordinary reinforced concrete bored pile 4 Locking foot cable

[0049] 5 Structural side wall 6 Concrete support

[0050] 7 Steel support 8 Structural floor

[0051] 9 Structural middle slab 10 Structural roof

[0052] 11 Glass fiber reinforced plastic bored pile 12 Ordinary reinforcement;

[0053] 13 Glass fiber reinforced plastic 14 U-shaped fastener

[0054] 15 Strengthening ring beam 16 Longitudinal tension channel steel

[0055] 17 Bolt 18 Grouting steel pipe

[0056] 19 Plywood 20 Second corrugated square wood

[0057] 21 Main square timber 22 Wheel buckle scaffolding

[0058] 23 I-beam gantry. DETAILED DESCRIPTION

[0059] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and embodiments:

[0060] like Figures 1 - 19 As shown, a construction method for constructing a ventilation shaft behind a shield tunnel section includes the following steps:

[0061] ⅰ. Construct the ventilation shaft enclosure structure in the excavation section

[0062] According to the shield section line and the layout requirements of the internal building rooms of the shield section ventilation shaft, the outer contour line of the ventilation shaft structure is arranged to meet the requirements of ventilation shaft use and driving limit. In combination with the geological conditions of the shield section, bored cast-in-place piles are constructed at the outer contour, and the bored cast-in-place piles are evenly distributed to form the ventilation shaft enclosure structure;

[0063] ⅱ. The shield machine removes the surrounding structure and assembles the shield segments

[0064] Adjust the shield machine so that the cutter head cuts and breaks the bored piles on one side of the retaining structure, and then continue to excavate forward. Then the cutter head cuts and breaks the bored piles on the other side of the retaining structure until the cutter head passes through the interval ventilation shaft range and assembles the shield segments.

[0065] ⅲ. Install longitudinal tensioning components at the shield inlet and outlet shafts

[0066] Install the tensioning components in the assembled shield segments, and the tensioning components are evenly distributed in the shield segments in an annular manner;

[0067] ⅳ. Excavation of ventilation shaft foundation pit

[0068] Excavate the soil and set up the foundation pit support system, then remove the shield segments within the wind shaft range, and install the locking anchor cable 4 between the wind shaft bored piles;

[0069] ⅴ. Casting and construction of ventilation shaft structure

[0070] The foundation pit continues to be excavated to the position of the structural bottom plate 8 of the air shaft, the bottom plate steel bars are tied, concrete is poured, and then the side wall steel bars are tied. An I-beam gantry 23 is erected on the bottom plate, and plywood 19, main rib square timber 21, secondary rib square timber 20 are arranged between the I-beam gantry 23 and the structural side wall 5. A wheel-lock scaffolding 22 is erected, and the air shaft structural side wall 5, the structural middle plate 9 and the end wall reinforcement ring beam 15 are poured. Finally, the structural top plate 10 is constructed, and the soil is backfilled to complete the construction of the entire interval air shaft.

[0071] In Step ⅰ, the bored cast-in-place piles include glass fiber reinforced plastic (GFRP) bar bored cast-in-place piles 11 located in the shield tunneling area and ordinary steel bar bored cast-in-place piles 3 located outside the shield tunneling area.

[0072] The GFRP bar bored cast-in-place piles 11 include GFRP bars 13 that are easy to break during shield machine tunneling. The GFRP bars 13 are fixed to the ordinary steel bars 12 in the GFRP bar bored cast-in-place piles 11 through a connecting component, and the connecting component includes a U-shaped fastener 14, a clamping plate, and a nut.

[0073] In Step ⅱ, segment lining 1 is assembled with staggered joints outside the ventilation shaft area, and segment lining 2 is assembled with longitudinal joints inside the ventilation shaft area.

[0074] In Step ⅳ, excavating the soil mass and erecting the foundation pit support system includes the following: excavating the soil mass inside the ventilation shaft from top to bottom, and timely erecting the first concrete support 6 and the second and third steel supports 7.

[0075] In Step ⅳ, demolishing the shield segment lining inside the ventilation shaft specifically includes the following: when excavating to 0.5 m above the shield segment lining, manual excavation is adopted. After the shield segment lining is exposed, the longitudinal joint segment bolts are disassembled in the tunnel, the top wedge-shaped segment is broken, and other segments are successively demolished and hoisted out of the ventilation shaft.

[0076] In Step ⅳ, constructing the locking foot anchor cables 4 between the bored cast-in-place piles of the ventilation shaft specifically includes the following: after demolishing the shield segment lining, two rows of locking foot anchor cables 4 are driven into the side wall of the bored cast-in-place piles to ensure the anti-overturning stability of the foundation pit.

[0077] In Step ⅴ, grouting steel pipes 18 are reserved at the interface between the ventilation shaft and the shield segment lining for grouting to seal the gap and prevent water leakage.

[0078] In Step ⅲ, the tensioning component includes a longitudinal tensioning channel steel 16. An assembly hole is formed at the bottom of the groove of the longitudinal tensioning channel steel 16. A mounting hole corresponding to the assembly hole is formed on the inner wall of the shield segment lining 1 assembled with staggered joints. A threaded sleeve is arranged in the mounting hole, and a bolt passes through the assembly hole of the longitudinal tensioning channel steel 16 and is screwed into the threaded sleeve.

[0079] Before demolishing the shield segment lining inside the ventilation shaft, the bolts between the longitudinal tensioning channel steel and the shield segment lining outside the ventilation shaft need to be retightened.

[0080] The ventilation shaft structure of the present invention includes a structural floor slab 8 located at the lower end of the foundation pit. An I-beam portal frame 23 and structural side walls 5 on both sides are erected on the structural floor slab 8. A structural roof slab 10 is arranged on the structural side walls 5. The structural side walls 5 are connected to the shield structure, and a strengthening ring beam 15 is arranged between the structural side walls 5 and the shield structure.

[0081] Between the I-beam gantry 23 and the structural side wall 5, there are secondary lath square timbers 20, primary lath square timbers 21, and plywood 19.

[0082] The I-beam gantry 23, primary lath square timbers 21, secondary lath square timbers 20, and plywood 19 are temporary structures for pouring the side wall, middle slab, and top slab, and are temporary formworks.

[0083] Between the two structural side walls 5, there are also a structural middle slab 9 in the middle and a concrete support 6 at the top.

[0084] The shield structure includes shield staggered-joint segment linings 1 outside the structural side wall 5 and shield circumferential-joint segment linings 2 removed inside the structural side wall 5.

[0085] At the inner walls of the shield staggered-joint segment linings 1 on both sides, there are tensioning assemblies for longitudinally tensioning the shield staggered-joint segment linings 1.

[0086] The tensioning assembly includes a longitudinal tensioning channel steel 16. An assembly hole is formed at the bottom of the groove of the longitudinal tensioning channel steel 16. At the inner wall of the shield staggered-joint segment lining 1, a mounting hole corresponding to the assembly hole is formed. A threaded sleeve is arranged in the mounting hole, and a bolt 17 passes through the assembly hole of the longitudinal tensioning channel steel 16 and is screwed into the threaded sleeve.

[0087] Outside the structural side wall 5, there is a drilled cast-in-place pile assembly, which includes glass fiber reinforced drilled cast-in-place piles 11 in the shield passing area and ordinary steel bar drilled cast-in-place piles 3 in the non-shield passing area.

[0088] The glass fiber reinforced drilled cast-in-place pile 11 includes glass fiber bars 13 that are easy to break during the tunneling of the shield machine. The glass fiber bars 13 and the ordinary steel bars 12 in the glass fiber reinforced drilled cast-in-place pile 11 are fixed through a connecting assembly.

[0089] The connecting assembly includes a U-shaped fastener 14. External threads are formed at the two free ends of the U-shaped fastener 14. The free ends of the U-shaped fastener 14 pass through a clamping plate and are then screwed into nuts. The ordinary steel bar 12 and the glass fiber bar 13 are located in the clamping cavity of the U-shaped fastener 14 and the clamping plate.

[0090] Outside the structural side wall 5, there are also locking foot anchor cables 4 for reinforcement. Embodiment

[0091] ⅰ. Driving the retaining structure of the ventilation shaft in the excavation section

[0092] As Figures 1 - 7As shown, according to the requirements of the layout of the section lines and the internal building rooms of the section ventilation shaft, the outer contour line of the ventilation shaft structure is arranged to meet the requirements of the use of the ventilation shaft and the driving limit. Combined with the geological conditions of the section, ordinary reinforced bored piles 3 with a pile diameter of 0.8m and a spacing of 1.4m are constructed near the non-tunnel gates. The ordinary reinforced concrete piles 12 with a diameter of 20 are 20 in total.

[0093] Glass fiber reinforced bored piles 11 are constructed at the tunnel entrance, and the pile body reinforcement uses U-shaped fasteners 14 to connect the glass fiber reinforcement 13 with the ordinary reinforcement 12 to ensure that the overlap length is met.

[0094] ⅱ. The shield machine removes the surrounding structure and assembles the shield segments

[0095] like Figures 8 - 9 As shown, before the shield reaches the retaining piles of the interval ventilation shaft, the shield is staggered to assemble the pipe segments 1, the shield posture is adjusted, the cutter head cuts the small-mileage retaining piles with glass fiber reinforcement, and the tunneling continues to move forward and assemble the through-seam pipe segments 2. The cutter head cuts the large-mileage retaining piles with glass fiber reinforcement. The shield machine cutter head passes through the range of the interval ventilation shaft and continues to move forward and stagger the shield to assemble the pipe segments 1.

[0096] ⅲ. Install longitudinal tensioning components at the shield inlet and outlet shafts

[0097] like Figures 10 - 14 As shown, longitudinal tensioning components are arranged between the shield staggered assembly segments 1 on both sides of the shield tunnel inlet and outlet. Six longitudinal tensioning channels 16 are installed in each segment, and the six longitudinal tensioning channels 16 are fixed in the shield segment by segment bolts 17. Before removing the through-seam assembly segments 2 in the wind shaft, the 12 rings of segment bolts before and after the tunnel doors on both sides of the wind shaft need to be re-tightened.

[0098] ⅳ. Excavation of ventilation shaft foundation pit

[0099] like Figures 15 - 16 As shown, first, the foundation pit support system is set up

[0100] Excavate the soil within the air shaft from top to bottom, and erect the first concrete support 6 and the second and third steel supports 7 in time.

[0101] Then, remove the pipe segments within the air shaft.

[0102] Dig to 0.5m above the pipe segment using manual excavation. After the pipe segment is exposed, remove the through-seam pipe segment bolts in the hole, break the top wedge-shaped pipe segment, and remove the other pipe segments one by one and lift them out of the air shaft.

[0103] Finally, the anchor cable between the wind shaft retaining piles is installed.

[0104] After the segment is removed, two rows of locking-foot anchor cables 4 are driven on the side wall of the retaining pile, with a vertical spacing of 3 m to ensure the anti-overturning stability of the foundation pit. The free section of the anchor cable is 6 m, the anchored section is 6 m, and the spacing is 1.4 m.

[0105] ⅴ. Pour the structure of the construction ventilation shaft

[0106] As Figures 17 - 19 shown, the foundation pit is continuously excavated to the position of the structural floor 8, the floor steel bars are tied and concrete is poured, the side wall steel bars are tied, the steel I-beam gantry 23 is erected on the floor, the plywood 19, the secondary lath square timbers 20, the main lath square timbers 21 are arranged between the gantry and the side wall, and the ring-lock type scaffolding 22 is erected. The structural side wall 5, the structural middle slab 9 and the end wall strengthening ring beam 15 of the ventilation shaft are poured. A grouting steel pipe 18 is reserved at the interface between the interval ventilation shaft and the interval shield segment for grouting to seal the gap and prevent water leakage. Finally, the structural roof slab 10 is constructed, and the soil is backfilled to complete the main structure of the entire interval ventilation shaft.

[0107] The present invention utilizes the characteristics of high strength and good stability of the medium-weathered rock stratum, and the characteristics of low shear failure strength and high flexural strength of glass fiber bars. By first constructing the interval tunnel, cutting the retaining pile of the ventilation shaft, and then constructing the main structure of the interval ventilation shaft, the previously constructed shield segments are removed. At the same time, anchor cables are used to temporarily reinforce the foundation pit to ensure the risk of instability of the foundation pit excavation due to insufficient embedment depth of the retaining pile, and to ensure that the foundation pit excavation does not affect the normal shield tunneling in the lower interval.

[0108] The present invention sets glass fiber reinforced bored cast-in-place piles at the crossing of the shield interval, which is convenient for the shield machine to break through and does not affect the normal non-stop tunneling of the shield interval. By assembling the shield through-joint segments inside the ventilation shaft structure, it is convenient to take out the segments during the construction of the ventilation shaft. The shield segments can be effectively connected through the strengthening ring beam and the longitudinal tensioning channel steel.

[0109] The present invention can realize the technology of prior tunneling construction of the shield interval and subsequent construction of the main structure of the interval ventilation shaft, and has the advantages of small cross-influence during construction, small influence on the surrounding environment, slowdown of the construction period pressure, safety and reliability, etc., and can be applied to the shield interval project with an interval ventilation shaft.

Claims

1. A construction method for a post-construction ventilation shaft in a shield tunnel section, characterized in that: The following steps are involved: (i) Construction of ventilation shaft enclosure structure in the post-excavation section According to the shield section line and the layout requirements of the internal building rooms of the shield section ventilation shaft, the outer contour line of the ventilation shaft structure is arranged to meet the requirements of ventilation shaft use and driving limit. In combination with the geological conditions of the shield section, bored cast-in-place piles are constructed at the outer contour, and the bored cast-in-place piles are evenly distributed to form the ventilation shaft enclosure structure; (ii) The shield machine removes the surrounding structure and assembles the shield segments Adjust the shield machine so that the cutter head cuts and breaks the bored piles on one side of the retaining structure, and then continue to excavate forward. Then the cutter head cuts and breaks the bored piles on the other side of the retaining structure until the cutter head passes through the interval ventilation shaft range and assembles the shield segments. (iii) Install longitudinal tensioning components at the shield inlet and outlet shafts Install the tensioning components in the assembled shield segments, and the tensioning components are evenly distributed in the shield segments in an annular manner; (iv) Excavation of ventilation shaft foundation pit Excavate the soil and set up the foundation pit support system, then remove the shield segments within the wind shaft range, and install the locking anchor cables between the wind shaft bored piles; (v) Casting and construction of ventilation shaft structure The foundation pit is excavated to the structural bottom plate of the ventilation shaft, the bottom plate reinforcement is tied, concrete is poured, and then the side wall reinforcement is tied. An I-beam gantry is erected on the bottom plate, plywood, main rib square timber, secondary rib square timber are arranged between the gantry and the side wall, and a wheel-lock scaffolding is erected. The side wall of the ventilation shaft structure, the structural middle plate and the end wall reinforcement ring beam are poured. Finally, the structural top plate is constructed, and the soil is backfilled to complete the construction of the ventilation shaft in the entire section. The wind shaft structure comprises a structural bottom plate (8) located at the lower end of the foundation pit, an I-beam door frame (23) and structural side walls (5) located on both sides of the structural bottom plate (8), a structural top plate (10) is arranged on the structural side walls (5), the structural side walls (5) are connected to the shield structure, and a reinforcing ring beam (15) is arranged between the structural side walls (5) and the shield structure; Secondary square timber (20), primary square timber (21), and plywood (19) are arranged between the I-beam door frame (23) and the structural side wall (5); The I-beam door frame (23), the main square timber (21), the secondary square timber (20), and the plywood (19) are temporary structures for the purpose of casting the side walls, the middle plate, and the top plate, and are temporary formwork; A structural middle plate (9) located in the middle and a concrete support (6) located at the top are also arranged between the two structural side walls (5).

2. The construction method of a post-construction air shaft in a shield tunnel section according to claim 1, characterized in that: The bored piles in step (i) include glass fiber reinforced bored piles (11) located in the shield tunneling area and ordinary reinforced bored piles (3) located in the non-shield tunneling area.

3. The construction method of a post-construction ventilation shaft in a shield tunnel section according to claim 2, characterized in that: The glass fiber reinforced bored pile (11) comprises a glass fiber reinforced bar (13) which is easy to break when a shield machine is excavating. The glass fiber reinforced bar (13) is fixed to the ordinary steel bar (12) in the glass fiber reinforced bored pile (11) via a connecting assembly. The connecting assembly comprises a U-shaped fastener (14), a clamping plate, and a nut.

4. The construction method of a post-construction ventilation shaft in a shield tunnel section according to claim 1, wherein: In step (ii), staggered assembly of segments by shield machine (1) is performed outside the wind shaft, and through-assembly of segments by shield machine (2) is performed within the wind shaft.

5. The construction method of a post-construction ventilation shaft in a shield tunnel section according to claim 1, characterized in that: In step (iv), the excavation of the soil mass and the erection of the foundation pit support system include the following: Excavate the soil mass within the air shaft from top to bottom, and timely erect the first concrete support (6) and the second and third steel supports (7).

6. The construction method of a post-construction air shaft in a shield tunnel section according to claim 1, characterized in that: In step (iv), the demolition of the shield segments within the air shaft specifically includes the following: Excavate to a position 0.5 m above the shield segment, and use manual excavation. After the shield segment is exposed, remove the circumferential joint bolts in the tunnel. Demolish the top wedge-shaped segment, and then successively remove the other segments and hoist them out of the air shaft.

7. The construction method of a post-construction air shaft in a shield tunnel section according to claim 1, characterized in that: In step (iv), the construction of the locking foot anchor cables between the bored cast-in-place piles of the air shaft specifically includes the following: After the shield segments are demolished, drive two rows of locking foot anchor cables (4) on the side wall of the bored cast-in-place piles to ensure the anti-overturning stability of the foundation pit.

8. The construction method of a post-construction air shaft in a shield tunnel section according to claim 1, characterized in that: In step (v), a grouting steel pipe (18) is reserved at the interface between the air shaft and the shield segment for grouting to seal the gap and prevent water leakage.

9. The construction method of a post-construction ventilation shaft in a shield tunnel section according to claim 4, characterized in that: In step (iii), the tensioning assembly includes a longitudinal tensioning channel steel (16). An assembly hole is formed at the bottom of the groove of the longitudinal tensioning channel steel (16). A mounting hole corresponding to the assembly hole is formed on the inner wall of the shield staggered joint segment (1). A threaded sleeve is arranged in the mounting hole, and a bolt (17) passes through the assembly hole of the longitudinal tensioning channel steel (16) and is screwed into the threaded sleeve.

10. The construction method of a post-construction air shaft for a shield tunnel section according to claim 9, characterized in that: Before demolishing the shield segments in the air shaft, the bolts between the longitudinal tensioning channel steel (16) and the shield segments outside the air shaft need to be re-tightened.

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