A method for demolishing the air shaft air duct in the section constructed by the mining method of shield tunnel segments and the method

Abstract

A method for demolishing segment lining of a shield tunnel in a mine shaft air duct section and the air duct, which includes horizontally excavating the air duct of the mine shaft on one side of an existing shield tunnel; sequentially excavating the air duct of the mine shaft in a step method by layer and section according to the pilot tunnel numbers and constructing the initial support; the upper pilot tunnel is constructed above the top of the tunnel, horizontally spanning the existing tunnel, and excavated to the end wall A of the air duct of the mine shaft for plugging, and the lower pilot tunnel is constructed below the top of the tunnel, horizontally excavated to the end wall B of the air duct of the mine shaft near the outer edge of the left-line tunnel for plugging; constructing the waterproof layer and the second lining floor structure of the air duct of the mine shaft; respectively excavating the No. 1 and No. 2 vertical shafts on both sides of the two tunnels in the air duct of the mine shaft; demolishing the shield segments in the air duct of the mine shaft; the initial support of the end wall B and the side wall of the No. 1 vertical shaft are gradually demolished along with the demolition of the segment lining of the left-line tunnel, and the tunnel is connected with the air duct of the mine shaft, the No. 1 vertical shaft and the No. 2 vertical shaft. It realizes that the shield passes through first and then the segment lining of the tunnel is demolished, and is applicable to projects that need to temporarily add air shafts such as adding stations and reducing stations.

Description

Technical Field

[0001] The invention relates to the technical field of subway engineering construction, and in particular to an air shaft and air duct of a shield tunnel segment mining method construction interval and a method thereof. Background Art

[0002] Metro construction is a large-scale, long-distance linear engineering project, and the construction period risk has become increasingly prominent in recent years, especially in the construction of long and large express lines in recent years, with many long-distance interval tunnels. In order to meet the needs of subway operation and evacuation, long-distance tunnels often need to add interval ventilation shafts. If the interval ventilation shaft is completed before the shield tunnel is passed, the delay in the interval ventilation shaft construction period often affects the subsequent shield construction, resulting in a longer total construction period.

[0003] In addition, similar situations also exist in subway stations. Generally, subways are located in prosperous commercial areas with busy ground traffic. The construction period is largely restricted by the progress of demolition. After the tunnel is opened, problems such as adding or reducing stations or delaying the construction of stations are common. In this case, it is often necessary to add temporary ventilation shafts and section substations in the station area to meet the needs of traffic operations.

[0004] Therefore, it is urgent to use a combination of underground tunnel excavation methods to flexibly solve the problem of implementing shield tunneling first and then conducting design solutions and construction technology research on tunnel segment removal. Summary of the invention

[0005] The present invention provides a method for breaking the air shaft and duct in the construction section of the shield tunnel segment mining method, and its purpose is to solve the technical problem of first shield passing the station and then breaking the air shaft and duct in the construction section of the shield segment. It is used to solve the technical problems that the shield construction progress is restricted and the node construction period cannot be met after the shield passes the station after the construction of the air shaft and duct in the prior art. It can also be used as a construction method for adding a temporary air shaft or a substation in the section after the shield section passes.

[0006] The technical solution of the present invention is as follows:

[0007] A method for breaking the air shaft and air duct of the shield tunnel segment mining method construction interval comprises the following steps:

[0008] Step 1: Excavate the wind shaft and air duct horizontally on one side of the existing shield tunnel;

[0009] First, advance deep hole grouting is performed to reinforce the soil mass 101 of the air shaft and air duct vault. Then, the air shaft and air duct are excavated in layers and sections according to the guide hole numbers using the step method, and initial support is constructed.

[0010] The upper pilot tunnel is constructed above the top of Tunnel 3 with initial support, spanning horizontally across the existing tunnel, excavated until the end wall of the air shaft air duct is blocked, and End Wall 1-A is constructed, and it is excavated into the first basement level 1; the lower pilot tunnel is constructed below the top of the tunnel with initial support, excavated horizontally until it is blocked near the outer edge of the left-line tunnel, End Wall 2-B is constructed, and it is excavated into the second basement level 2.

[0011] Step 2: Construct the waterproof layer and the secondary lining structure of the air shaft air duct;

[0012] Construct the waterproof layer and the secondary lining structure of the outside of the track area 4 on the first basement level of the air shaft air duct, the track area 6 on the first basement level, and the outside of the track area 5 on the second basement level of the air shaft air duct, and retain the side wall and the floor slab structure of the track area on the second basement level; and reserve the No. 1 shaft opening 10, the No. 2 shaft opening 12, the hoisting opening 9 at the vault of the left-line tunnel, and the hoisting opening 11 at the vault of the right-line tunnel on the middle partition of the track area 6 on the first basement level. Among them, the hoisting opening 11 at the vault of the right-line tunnel can also be used as a permanent piston air hole; the No. 1 shaft is located between the two left and right tunnels, and the No. 2 shaft is located on the side of the right-line tunnel; the hoisting opening 9 at the vault of the left-line tunnel and the hoisting opening 11 at the vault of the right-line tunnel are located at the tops of the left-line tunnel and the right-line tunnel.

[0013] Step 3: Excavate the No. 1 and No. 2 shafts in the air shaft air duct:

[0014] Piecemeal break the temporary inverted arch of the upper pilot tunnel in the air shaft air duct within the scope of the No. 1 shaft opening and the No. 2 shaft opening, and invert the shaft wall to excavate the shaft;

[0015] Step 4: Construct the secondary lining floor slab 14 and part of the side wall of the air shaft air duct in the No. 1 and No. 2 shafts, including the upper part 15 of the side wall in the width direction of the air shaft air duct and the upper part 121 of the outer side wall of the No. 2 shaft far from the tunnel;

[0016] Step 5: Demolish the shield segments in the air shaft air duct;

[0017] After the construction of the secondary lining floor slab structure and the side wall structure of the No. 1 shaft and the No. 2 shaft in the air shaft air duct is completed, first demolish the segments of the left-line tunnel, construct a movable steel ring support 18 on the first ring of segments to be demolished, and first demolish the middle first ring of segments ①; move the movable steel ring support to the next ring of segments to be demolished, and symmetrically and gradually demolish the segments on both sides of the first ring of segments until reaching the side wall 8 of the air shaft air duct; End Wall 2-B and the initial support of the side wall of the No. 1 shaft are gradually demolished along with the demolition of the segments of the left-line tunnel, and the left-line tunnel is connected to the air shaft air duct and the No. 1 shaft;

[0018] Step 6: Construct the secondary lining structure of the air shaft air duct within the scope of the demolished segments;

[0019] (1) Spray C20 concrete with double-layer steel mesh to seal the soil on the outside of the side wall of the air shaft duct, excavate the soil at the bottom of the segment of the left-line tunnel that has been demolished to the structural floor slab, and use C20 sprayed concrete and I22a steel supports for bottom sealing;

[0020] (2) Apply the waterproof layer on the floor slab within the range of the segments that have been demolished, tie the steel bars, erect the scaffolding, formwork and pour the second lining floor slab structure. This second lining floor slab structure is set within the soil on the outside of the air shaft and the bottom sealing, and then construct the side wall (8) and the ring beam 21 of the air shaft duct;

[0021] After the demolition of the segments of the left-line tunnel is completed, demolish the segments of the right-line tunnel in the same way and construct the second lining structure of the air shaft duct within the range of the segments that have been demolished to realize the connection between the air shaft duct and the left-line, right-line tunnels, No. 1 shaft, and No. 2 shaft.

[0022] In the method for constructing the air shaft duct in the mining method by demolishing the segments of the shield tunnel,

[0023] In Step 1, the air shaft duct is set as a four-layer 12-pilot tunnel duct. Excavate each chamber and construct the initial support in the order of the bench method according to the pilot tunnel numbers. The bench length is 3 - 5 meters. Timely install the locking foot anchor pipes. The longitudinal excavation lengths of each chamber are staggered by no less than 6m; the upper pilot tunnels (chambers 1 - 6) cross the existing tunnel and are excavated to the end wall for blocking, and construct End Wall A; the lower pilot tunnels (chambers 7 - 12) are constructed to the outer edge of the left-line tunnel and then blocked, and construct End Wall B;

[0024] When excavating the shaft in Step 3, demolish the temporary inverted arches of the upper pilot tunnels (No. 2, 4, and 6) within the air shaft duct at the openings of No. 1 shaft and No. 2 shaft in blocks. Timely erect the shaft grid, connect the longitudinal tie bars, and erect the steel supports; the vertical excavation step distance is the grid spacing, and the vertical spacing of the steel supports is the grid spacing; when excavating to the bottom of the shaft, timely seal the bottom; the construction should be carried out in the order of No. 1 shaft and No. 2 shaft first. During the shaft construction process, deep-hole grouting reinforcement should be carried out on both sides of the shaft in a timely manner;

[0025] When constructing the second lining floor slab and part of the side wall of the air shaft duct in the shaft in Step 4, remove the lower two steel supports in the shaft, lay the waterproof layer, tie the steel bars, and pour the second lining floor slab 14 and the lower part of the side wall; after the second lining floor slab reaches 80% of the design strength, erect the scaffolding, partially demolish the temporary middle partition wall of the shaft, lay the waterproof layer, tie the steel bars, formwork and pour the upper part of the side wall (15) in the width direction of the air shaft duct and the upper part of the outer side wall 121 of No. 2 shaft far from the tunnel and connect them to the middle partition board and the second lining structure of the underground first-layer track area.

[0026] In the method for constructing the air shaft duct in the mining method by demolishing the segments of the shield tunnel, Step 5 of demolishing the segments further includes the following steps:

[0027] (1) Construction preparation steps:

[0028] ① Erect steel frames on the middle partition of the air shaft air duct, and lay 2 I32a steel beams 22 respectively at the hoisting openings 9 on the crown of the left-line tunnel and 11 on the crown of the right-line tunnel. Fix 2 10t chain hoists on different steel beams respectively to facilitate the hoisting and outward transportation of segments and materials;

[0029] ② Assemble the mobile steel ring support 18; Assemble the mobile steel ring support at the position of the segment to be demolished. The jacks radially symmetrically distributed in the hydraulic support system of the mobile steel ring support can provide support stress for the segment for removing the connecting bolts in the early stage. In the later stage, when demolishing the segment, the independently working jacks can not only provide working space for the segment to be demolished by unloading the hydraulic rod, but also provide continuous support stress for the segment to be demolished, ensuring the overall stability of the segments to be demolished in the demolition ring;

[0030] (2) Specific steps for segment demolition:

[0031] ① First, demolish the middle segment, that is, demolish the first ring of segments ①. Erect the mobile steel ring support on the first ring of segments, and provide support stress for the segments through the hydraulic loading system of the mobile steel ring support;

[0032] ② Drill through the grouting holes of the segments at the crown position, install the segment hoisting bolts on the grouting holes of the segments to be demolished, and install these bolts on the lifting ropes of the chain hoists; Remove all the longitudinal connecting bolts above the midline between the first ring and the 2nd and 3rd rings on both sides;

[0033] ③ Cut the first ring of wedge-shaped K-block segments at the crown with a water drill or a wire saw machine. Make a cut around the K-block segments, relieve the longitudinal jacking force of the segments, make them separate from the surrounding segments, and remove the K-block segments; During the demolition process, the jacks on both sides of the K-block segments of the mobile steel ring support are gradually unloaded, and the lifting ropes of the chain hoists are slowly tightened, and transported out of the tunnel through the reserved hoisting openings in the air shaft air duct;

[0034] ④ Then demolish the adjacent segments. Install the segment hoisting bolts in the bolt holes of the segments to be demolished, and remove the bolts connected to the adjacent segments; Slowly tighten the chain hoist, and the hydraulic jacks of the mobile steel ring support are symmetrically and segmented unloaded, and the segments are hoisted out; Demolish the segments within 180° of the crown of the first ring of segments;

[0035] ⑤ Use the same method as above to demolish ring by ring symmetrically on both sides of the first ring of segments according to the serial numbers; Demolish the segments within 180° of the crown of each ring of segments. Before demolition, it is necessary to erect the mobile steel ring support on this segment. After the segment demolition is completed, move the mobile steel ring support to the next ring of segments to be demolished;

[0036] ⑥ Cut the segments within 180° at the bottom of the segment into small pieces with a water drill or a wire saw machine, and remove the segmented and broken segments with an excavator.

[0037] The described method for demolishing the air shaft and air duct in the construction section of the shield tunnel segment by the mining method, wherein, before the excavation of the air shaft and air duct, the following reinforcement steps are also included:

[0038] (1) Before the excavation of the air shaft and air duct, remove the longitudinal connection bolts between the permanent segments and the segments to be demolished, and install steel ring internal supports 16 with an outer diameter equal to the inner diameter of the segment on 10 segments on both sides of the shield tunnel and the air shaft and air duct. Connect the steel rings with I25b steel longitudinal connection beams 17 to prevent the increase of segment deformation during the construction process;

[0039] (a) The steel ring is assembled and connected by arc-shaped steel plates. The steel ring is provided with two I40b double-ply I-beam vertical supports 23 with a spacing of 2000 mm; three I25b double-ply I-beam horizontal supports 24 are provided, and the first one is 1300 mm from the top.

[0040] b) Set four I25b steel longitudinal connection beams 17 at the upper, lower, left, and right cross centers of each steel ring for longitudinal connection.

[0041] (2) Before the erection of the steel ring internal support, the segment demolition section is radially grouted and reinforced through the grouting holes reserved on the segment from the tunnel.

[0042] Grout and reinforce the surrounding soil of 4 permanent segments on both sides of the air shaft and air duct from the tunnel. The radial grouting length is 2 m. Seven grouting holes are drilled in the upper part of each segment and four grouting holes are drilled in the lower part. The grouting slurry adopts single-component cement slurry. During the grouting operation, observe the changes in grouting pressure and flow rate, and strictly control the grouting parameters;

[0043] (3) Auxiliary grouting reinforcement in the vertical shaft and the pilot tunnel of the air duct

[0044] Before the segment demolition, grout and reinforce the surrounding soil of 4 adjacent segments on both sides of the air shaft and air duct.

[0045] At the lower pilot tunnel near the end wall 2B, drill grouting holes for reinforcement from the initial support of the lower pilot tunnel of the air shaft and air duct. The horizontal spacing of the grouting holes is 1 m, the vertical spacing is 1 m, and they are arranged in a plum blossom shape, with a drilling length of 4 m; near the vertical shaft, when constructing the initial support in the vertical shaft, drill grouting holes horizontally for reinforcement. The horizontal spacing of the grouting holes is 1 m, the vertical spacing is 1 m, and they are arranged in a plum blossom shape, with a drilling length of 4 m; the slurry adopts single-component cement slurry. During the grouting process, strictly control the grouting parameters to ensure that the diffusion range of the slurry radius reaches 0.5 m, and the slurry between the grouting holes can effectively overlap.

[0046] An interval air shaft air duct for breaking through shield tunnel segments during the construction of a mining method includes an existing tunnel, where the existing tunnel includes a left-line tunnel and a right-line tunnel. It is characterized in that it also includes an underground first floor 1 and an underground second floor 2 of the air shaft air duct constructed by the pilot tunnel bench method. The underground first floor horizontally crosses the two existing tunnels above the tops of the left and right-line tunnels and constructs the initial support until the end wall of the air shaft air duct is blocked, and a first end wall A is set. The underground second floor is horizontally blocked from below the tunnel top to the outer edge of the adjacent left-line tunnel, and a second end wall B is set, and the initial support is constructed. A No. 1 shaft is set between the left and right-line tunnels, and a No. 2 shaft is set on the side of the right-line tunnel, and the initial support is constructed. A No. 1 shaft opening 10 and a No. 2 shaft opening 12 are set on the middle partition of the underground first floor 1. Within the scope of the air shaft air duct, the second end wall B, the segments of the left-line tunnel, the initial support of the side wall of the No. 1 shaft, the segments of the right-line tunnel, and the initial support of the side wall of the No. 2 shaft are synchronously broken through, so that the air shaft air duct is connected to the left-line tunnel, the right-line tunnel, the No. 1 shaft, and the No. 2 shaft.

[0047] In the interval air shaft air duct for breaking through shield tunnel segments during the construction of a mining method, it is characterized in that a secondary lining structure is provided for the underground first floor 1, the underground second floor 2, the breaking range of the segments of the left-line tunnel and the right-line tunnel, the No. 1 shaft, and the No. 2 shaft.

[0048] The technical feature of the present invention is that after the upper pilot tunnel of the air duct crosses the shield tunnel, under the protection of the initial lining and the secondary lining floor structure of the upper air duct, the inverted shaft wall is constructed for the initial support and the secondary lining structure on both sides of the shield, and then the initial support structure of the shaft side wall is broken through and the shield tunnel segments are broken through, and finally the pouring of the secondary lining floor structure of the air duct is completed.

[0049] The effects of the present invention

[0050] By combining several mined tunneling methods, the contradiction between the lag in the construction of the air shaft air duct and the restriction of the shield construction progress is effectively solved. At the same time, the risk of multiple starts and receptions of the shield when passing through the air shaft air duct can be avoided. It has the advantages of reasonable processes, safety and reliability, and can effectively shorten the construction period. At the same time, as a method for constructing an air shaft air duct that can solve the problem of the shield passing through first and then breaking through the tunnel segments, it can be applied to projects such as adding stations, reducing stations, and temporarily adding air shafts for postponed construction stations. Description of the drawings

[0051] Figure 1 It is a horizontal schematic diagram of the divided pilot tunnel excavation of the air shaft air duct of the present invention.

[0052] Figures 2(1) and 2(2) are longitudinal schematic diagrams of the divided pilot tunnel excavation of the air shaft air duct of the present invention, and Figure 2(2) is a 1-1 cross-sectional view of Figure 2(1).

[0053] Figure 3(1) and (2) are schematic diagrams of the second lining floor structure of the air shaft air duct of the present invention for the construction of the first basement floor and the second basement floor. Figure 3(2) is a sectional view taken along line 1-1 of Figure 3(1);

[0054] Figure 4(1) and (2) are schematic diagrams of the construction of the No. 1 shaft and the No. 2 shaft of the air shaft air duct of the present invention. Figure 4(2) is a sectional view taken along line 1-1 of Figure 4(1);

[0055] Figure 5(1) and (2) are schematic diagrams of the second lining structure of the No. 1 shaft and the No. 2 shaft of the air shaft air duct of the present invention. Figure 5(2) is a sectional view taken along line 1-1 of Figure 5(1);

[0056] Figure 6 is a schematic diagram of the construction for demolishing the shield segment of the air shaft air duct of the present invention,

[0057] Figure 7 is a schematic diagram of the construction for the side wall outer airspace soil and the bottom sealing after demolishing the shield segment of the air shaft air duct of the present invention,

[0058] Figure 8 is a schematic diagram of the second lining structure after demolishing the shield segment of the air shaft air duct of the present invention,

[0059] Figure 9 is a flow chart of the specific operation steps for demolishing the segment of the present invention,

[0060] Figure 10 is a schematic diagram of the layout of the partition opening and the setting of the steel beam in the air shaft air duct of the present invention,

[0061] Figure 11 is a schematic diagram of the segment hoisting of the present invention,

[0062] Figure 12 is a schematic diagram of the internal support of the steel ring of the present invention,

[0063] Figure 13 is a schematic diagram of the grouting reinforcement in the shield tunnel of the present invention,

[0064] Figure 14 is a schematic sectional view of the auxiliary grouting in the shaft of the present invention,

[0065] Figure 15 is a schematic plan view of the auxiliary grouting in the shaft of the present invention;

[0066] Figure 16 is a schematic elevation view of the air shaft air duct of the present invention;

[0067] Explanation of the drawing reference numbers:

[0068] Basement Level 1, Basement Level 2, Tunnel 3, Outside the Track Area on Basement Level 1, Outside the Track Area on Basement Level 2, Track Area on Basement Level 1, Floor Slab of the Track Area on Basement Level 2, Side Wall of the Air Shaft and Air Duct, Hoisting Opening at the Crown of the Left Tunnel, Opening of Shaft No. 1, Hoisting Opening at the Crown of the Right Tunnel 11 and Permanent Piston Air Duct, Opening of Shaft No. 2, Upper Part of the Outer Wall 121, Scaffold 13, Second Lining Floor Slab 14, Upper Part of the Side Wall 15, Inner Steel Ring Support 16, Longitudinal Connecting Beam of I25b Steel Section 17, Movable Steel Ring Support 18, Abutting Soils on the Outer Side of the Side Wall of the Air Shaft and Air Duct 19, Bottom Sealing 20, Ring Beam 21, I32a Steel Beam 22, Vertical Support 23, Horizontal Support 24, First Ring of Segments in the Middle ①, Second Ring of Segments ②, Third Ring of Segments ③, Fourth Ring of Segments ④, Fifth Ring of Segments ⑤, Sixth Ring of Segments ⑥, Seventh Ring of Segments ⑦, Eighth Ring of Segments ⑧, Ninth Ring of Segments ⑨; Detailed Implementation Manner

[0069] The following details the specific implementation manner of the present invention in conjunction with the accompanying drawings.

[0070] A method for demolishing the air shaft and air duct in the construction section of the shield tunnel segment by the mining method of the present invention mainly includes the following steps:

[0071] (1) Grout the soil mass at the crown of the air shaft and air duct by advanced deep-hole grouting. After achieving the reinforcement effect, excavate the air shaft and air duct layer by layer and section by section according to the cross-sectional dimensions of the air shaft and air duct and the engineering conditions.

[0072] As Figure 1 shown, the following details the construction of the air shaft and air duct by the 12 pilot tunnels in four layers as an example. Excavate each chamber and construct the primary support in the order of the bench method according to the pilot tunnel numbers. The bench length is 3 - 5 meters, and the foot-locking anchor pipes are constructed in a timely manner. The longitudinal excavation lengths of each chamber are staggered by no less than 6m;

[0073] As shown in Figures 2(1) and (2), the upper pilot tunnels (Chambers 1 - 6) are constructed from above the top of Tunnel 3 and the primary support is constructed. They span the existing tunnel horizontally and are excavated until the end wall of the air shaft and air duct is blocked, and End Wall A is constructed, and it is excavated into Basement Level 1; the lower pilot tunnels (Chambers 7 - 12) are constructed from below the top of the tunnel, and the primary support is constructed. They are excavated horizontally until they are blocked near the outer edge of the left tunnel, and End Wall B is constructed, and it is excavated into Basement Level 2;

[0074] (2) As shown in Figures 3(1) and (2), for the waterproof layer and the secondary lining structure on the outside of the track area on the first basement floor of the construction ventilation shaft air duct (4), in the track area on the first basement floor (6), and on the outside of the track area on the second basement floor (5), only the side wall on the second basement floor of the ventilation shaft air duct and the floor slab on the second basement floor of the track area (7) are retained to facilitate the removal of the segment lining. A 1st shaft opening (10), a 2nd shaft opening (12), a hoisting opening at the crown of the left-line tunnel (9), and a hoisting opening at the crown of the right-line tunnel (11) are reserved on the middle partition in the track area on the first basement floor (6). Among them, the hoisting opening at the crown of the right-line tunnel (11) can also be used as a permanent piston air hole. The 1st shaft is located between the two left and right tunnels, and the 2nd shaft is located on the side of the right-line tunnel. The hoisting opening at the crown of the left-line tunnel (9) and the hoisting opening at the crown of the right-line tunnel (11) are located at the tops of the left-line tunnel and the right-line tunnel.

[0075] (3) As shown in Figures 4(1) and (2), the temporary inverted arches of the ventilation shaft air duct (2, 4), and the 6th pilot tunnel in the areas of the 1st shaft and the 2nd shaft openings are demolished in sections. The shaft is excavated with the inverted well wall, the shaft grille is erected in a timely manner, the longitudinal tie bars are connected, and the steel supports are erected.

[0076] The vertical excavation step distance is the grille spacing, and the vertical spacing of the steel supports is the grille spacing. When the excavation reaches the bottom of the shaft, it is sealed in a timely manner. The construction should be carried out in the sequence of the 1st shaft first and then the 2nd shaft. During the shaft construction, deep-hole grouting reinforcement should be carried out on both sides of the shaft in a timely manner.

[0077] (4) The lower two steel supports in the shaft are removed, the waterproof layer is laid, the steel bars are tied, and the secondary lining floor slab (14) and part of the side wall are poured. After the secondary lining floor slab reaches 80% of the design strength, the scaffold is erected, the temporary middle partition wall in the shaft is partially demolished, the waterproof layer is laid, the steel bars are tied, and the formwork is supported to pour the upper part of the side wall in the width direction of the ventilation shaft air duct (15) and the upper part of the outer side wall of the 2nd shaft far from the tunnel (121) and connect them to the middle partition and the secondary lining structure in the track area on the first basement floor, as well as the upper part of the side wall in the width direction of the ventilation shaft air duct (15). As shown in Figures 5(1) and (2).

[0078] (5): Remove the shield segment lining in the ventilation shaft air duct;

[0079] As Figure 6 shown, after the construction of the secondary lining floor slab structures of the 1st shaft and the 2nd shaft in the ventilation shaft air duct is completed, first remove the segment lining of the left-line tunnel. A movable steel ring support (18) is constructed on the first ring of segment lining to be removed. First, remove the first ring of segment lining in the middle (①); move the movable steel ring support to the next ring of segment lining to be removed, and symmetrically and gradually remove the segment linings on both sides of the first ring of segment lining until reaching the side wall (8) of the ventilation shaft air duct. The secondary lining of the end wall 2B and the side wall of the 1st shaft are gradually removed along with the removal of the segment lining of the left-line tunnel, and the left-line tunnel is connected to the ventilation shaft air duct and the 1st shaft.

[0080] (6): Construct the secondary lining structure of the ventilation shaft air duct within the area where the segment lining has been removed; As Figure 7 、 8 shown,

[0081] (1) Spray C20 concrete with a double-layer steel mesh to seal the soil on the outside of the side wall of the air shaft air duct. Excavate the soil at the bottom of the segment of the left-line tunnel that has been removed until reaching the structural floor, and use C20 sprayed concrete and I22a steel supports for bottom sealing;

[0082] (2) Apply the waterproof layer on the floor slab within the range of the segments that have been demolished, tie the steel bars, erect the scaffolding, formwork and pour the secondary lining floor slab structure. This secondary lining floor slab structure is set within the soil on the outside of the air shaft air duct side wall (8) and the bottom sealing;

[0083] After the demolition of the segments of the left-line tunnel is completed, demolish the segments of the right-line tunnel in the same way and construct the secondary lining structure of the air shaft air duct within the range of the segments that have been demolished, so as to connect the air shaft air duct with the left-line, right-line tunnels, No. 1 shaft and No. 2 shaft to form the air shaft air duct. As shown in Figures 5 and 8. The bottom of the air shaft air duct, the bottom of No. 1 shaft and the bottom of No. 2 shaft are deeper than the tunnel.

[0084] The specific implementation plan for segment demolition is as follows:

[0085] The segment demolition is mainly implemented according to the following steps, see Figure 9 Flow chart.

[0086] (1) Construction preparation: Refer to Figure 10 Shown;

[0087] ① Erect a steel frame on the middle partition of the air shaft air duct, and lay 2 I32a steel beams 22 on the hoisting openings 9 at the crown of the left-line tunnel and 11 at the crown of the right-line tunnel respectively. Fix 2 10t chain hoists on different steel beams respectively to facilitate the hoisting and outward transportation of segments and materials;

[0088] ② The assembly of the mobile steel ring support 18 refers to Figure 11 Shown; Assemble the mobile steel ring at the position of the segment to be demolished. The jacks symmetrically distributed radially in the hydraulic support system of the mobile steel ring can provide support stress for the segment to remove the connecting bolts in the early stage. In the later stage, when demolishing the segment, the independent jacks can not only provide working space for the segment to be demolished by unloading the hydraulic rod, but also provide continuous support stress for the segment to be demolished, ensuring the overall stability of the segments to be demolished in the demolition ring;

[0089] (2) Segment demolition refers to Figure 6 、 9 、11 shown:

[0090] ① First, demolish the middle segment, that is, demolish the first ring of segments ①, erect the mobile steel ring support on the first ring of segments, and provide support stress for the segments through the hydraulic loading system of the mobile steel ring support;

[0091] ②Pierce the grouting holes of the segments at the crown position, install the segment lifting bolts on the grouting holes of the segment to be demolished, and attach the bolts to the lifting ropes of the chain hoist; Remove all the longitudinal connection bolts above the center line between the first ring of segments and the segments between the 2nd and 3rd rings.

[0092] ③Use a water drill or a rope saw machine to cut the first ring of wedge-shaped K-block segments at the crown. Make a cut around the K-block segments to remove the longitudinal jacking force of the segments, so that they are separated from the surrounding segments, and then remove the K-block segments; During the removal process, gradually unload the jacks on both sides of the K-block segments supported by the movable steel ring, slowly tighten the lifting ropes of the chain hoist, and transport them out of the tunnel through the reserved lifting opening in the air shaft air duct.

[0093] ④Then remove the adjacent segments. Install the segment lifting bolts in the bolt holes of the segments to be demolished, and remove the bolts connecting to the adjacent segments; Slowly tighten the chain hoist, and symmetrically and segmentally unload the hydraulic jacks of the movable steel ring support to lift out the segments; Remove the segments within the 180° range at the crown of the first ring of segments.

[0094] ⑤Using the same method, symmetrically remove the segments ring by ring in sequence on both sides of the first ring of segments; Remove the segments within the 180° range at the crown of each ring of segments. Before removal, a movable steel ring support needs to be erected on this segment. After the segment removal is completed, move the movable steel ring support to the next ring of segments to be demolished.

[0095] ⑥Cut the segments within the 180° range at the bottom of the segments into small pieces with a water drill or a rope saw machine, and use an excavator to remove the segmented and broken segments.

[0096] The protection measures during the segment removal are as follows:

[0097] (1) After the segments are removed, the arrangement state of the segments is broken, and the segments are in a loose state. The permanent segments tend to deform and the ovality increases.

[0098] The specific solution is: Before the excavation of the air shaft air duct in the mined tunnel, remove the longitudinal connection bolts between the permanent segments and the segments to be demolished, and install steel ring internal supports 16 with an outer diameter tightly fitting the inner diameter of the segments within 10 rings on both sides of the shield tunnel and the piston air duct, as Figure 12 shown. Use the I25b steel longitudinal connection beam 17 tie bars to tightly connect between the steel rings to prevent the segments from deforming and increasing during the construction process.

[0099] (a) The steel ring internal support (which is an existing technology) is assembled by small arc-shaped pieces. Place wooden wedges or concrete blocks inside at the joints, and use M5.8 grade φ24 bolts to rotate and tighten.

[0100] (b) Set two I40b double-rolled I-beam vertical supports 23 for the steel ring internal support, with a spacing of 2000mm; Set three I25b double-rolled I-beam horizontal supports 24, and the first one is 1300mm from the top.

[0101] (c) At the vertical and horizontal center points of each steel ring, four No. 25b steel longitudinal connecting beams 17 are arranged as full-length steel sections for tensioning and longitudinal connection.

[0102] (d) The steel supports shall be welded reliably, and the weld height shall not be less than 8 mm. See Figure 1 , as shown in Figure 2;

[0103] (2) See Figure 13 、 14 、as shown in Figures 15, before the excavation of the air shaft air duct, the segment demolition section is radially grouted and reinforced through the grouting holes reserved in the segments from inside the tunnel;

[0104] For the 4 rings of permanent segments on both sides of the air shaft air duct, grouting reinforcement is carried out from inside the tunnel to reinforce the surrounding strata of the segments. The radial grouting length is 2 m. 7 grouting holes are drilled in the upper part of each ring of segments and 4 grouting holes are drilled in the lower part. Different grouting points are selected for the odd-numbered rings and the even-numbered rings to ensure that the grouting holes of each ring are in the same plane. The grouting slurry adopts single-component cement slurry. During the grouting operation, the changes in grouting pressure and flow rate shall be observed, and the grouting parameters shall be strictly controlled.

[0105] (3) The auxiliary grouting reinforcement in the vertical shaft and the air duct pilot tunnel is as shown in Figure 15 、 Figure 16 ;

[0106] Before the segment demolition, the surrounding soil of the 4 adjacent rings of segments on both sides of the air shaft air duct is grouted and reinforced.

[0107] At the lower pilot tunnel near the end wall No. 2B, grouting holes are drilled from the primary support of the lower layer of the air shaft air duct pilot tunnel for reinforcement. The horizontal spacing of the grouting holes is 1 m, the vertical spacing is 1 m, and they are arranged in a plum blossom shape, with a drilling length of 4 m. Near the vertical shaft, when the primary support is constructed in the vertical shaft, grouting holes are drilled horizontally for reinforcement. The horizontal spacing of the grouting holes is 1 m, the vertical spacing is 1 m, and they are arranged in a plum blossom shape, with a drilling length of 4 m. The slurry adopts single-component cement slurry. During the grouting process, the grouting parameters shall be strictly controlled to ensure that the diffusion range of the slurry radius reaches 0.5 m and the slurry between the grouting holes can effectively overlap.

[0108] See Figure 16As shown in the figure, the cross - passage air shaft of the present invention for breaking through the shield tunnel segment in the mining method construction includes an existing tunnel. The existing tunnel includes a left - hand tunnel and a right - hand tunnel, and also includes the first basement 1 and the second basement 2 of the air shaft air duct constructed by the pilot - tunnel bench - cut method. The first basement crosses the two existing tunnels horizontally above the tops of the left - hand and right - hand tunnels and constructs the primary support until the end - wall of the air shaft air duct is blocked, and a first end - wall A is set. The second basement is blocked horizontally below the tunnel top to the outer edge of the adjacent left - hand tunnel, and a second end - wall B is set, and the primary support is constructed. A No. 1 shaft 100 is set between the left - hand and right - hand tunnels, and a No. 2 shaft 120 is set on the side of the right - hand tunnel, and the primary support is constructed. On the partition board of the first basement 1, a No. 1 shaft opening 10 and a No. 2 shaft opening 12 are set, as shown in Figure 5(1). Within the scope of the air shaft air duct, the second end - wall B, the segments of the left - hand tunnel, the primary support of the side wall of the No. 1 shaft, the segments of the right - hand tunnel, and the primary support of the side wall of the No. 2 shaft are synchronously broken through, so that the air shaft air duct is connected to the left - hand tunnel, the right - hand tunnel, the No. 1 shaft, and the No. 2 shaft.

[0109] For the cross - passage air shaft of the present invention for breaking through the shield tunnel segment in the mining method construction, the first basement 1, the second basement 2, the breaking - through scopes of the segments of the left - hand tunnel and the right - hand tunnel, the No. 1 shaft and the No. 2 shaft are provided with secondary lining structures.

Claims

1. A method for demolishing the air shaft and air duct in the section constructed by the mining method of shield tunnel segments, characterized in that, it includes the following steps: Step 1: Horizontally excavate the air shaft and air duct on one side of the existing shield tunnel; Firstly, grout the soil body (101) at the top of the air shaft and air duct with advanced deep-hole grouting. Then, excavate the air shaft and air duct in sequence by the bench method in layers and sections according to the pilot tunnel numbers, and construct the primary support; The upper pilot tunnel is constructed above the top of the tunnel (3) and the primary support is constructed. It crosses two existing tunnels horizontally, excavates to the end wall of the air shaft and air duct for plugging, and constructs end wall A. The underground first layer (1) is excavated. The lower pilot tunnel is constructed below the top of the tunnel and the primary support is constructed. It is horizontally excavated to the outer edge of the adjacent left-line tunnel for plugging, and end wall B is constructed. The underground second layer (2) is excavated; Step 2: Construct the waterproof layer and the secondary lining structure of the air shaft and air duct; Construct the waterproof layer and the secondary lining structure of the outside of the track area (4) on the underground first layer of the air shaft and air duct, the track area (6) on the underground first layer, and the outside of the track area (5) on the underground second layer, and retain the side wall and bottom plate structure of the track area on the underground second layer; and reserve a No. 1 shaft opening (10), a No. 2 shaft opening (12), a hoisting opening (9) at the crown of the left-line tunnel, and a hoisting opening (11) at the crown of the right-line tunnel on the middle partition of the track area (6) on the underground first layer. Among them, the hoisting opening (11) at the crown of the right-line tunnel can also be used as a permanent piston air hole; The No. 1 shaft is located between the left and right tunnels, and the No. 2 shaft is located on the side of the right-line tunnel; The hoisting openings (9) at the crowns of the left-line tunnel and the right-line tunnel are located at the tops of the left-line tunnel and the right-line tunnel; Step 3: Excavate the No. 1 and No. 2 shafts in the air shaft and air duct; Demolish the temporary inverted arch of the upper pilot tunnel in the air shaft and air duct within the ranges of the No. 1 shaft opening (10) and the No. 2 shaft opening (12) in blocks, and excavate the shaft by hanging the shaft wall; Step 4: Construct the secondary lining bottom plate (14) and part of the side wall of the air shaft and air duct in the No. 1 and No. 2 shafts, including the upper part (15) of the side wall in the width direction of the air shaft and air duct and the upper part (121) of the outer side wall of the No. 2 shaft far from the tunnel; Step 5: Demolish the shield tunnel segments in the air shaft and air duct; After the construction of the secondary lining bottom plate structure and the side wall structure of the No. 1 and No. 2 shafts in the air shaft and air duct is completed, first demolish the left-line tunnel segments. Install a movable steel ring support (18) on the first ring of segments to be demolished. First, demolish the middle first ring of segments ①; Move the movable steel ring support to the next ring of segments to be demolished, and symmetrically and gradually demolish the segments on both sides of the first ring of segments until reaching the side wall (8) of the air shaft and air duct; The initial support of the end wall B and the side wall of the No. 1 shaft are gradually demolished along with the demolition of the left-line tunnel segments, and the left-line tunnel is connected to the air shaft and air duct and the No. 1 shaft; Step 6: Construct the secondary lining structure of the air shaft and air duct within the range of the demolished segments; (1) Hang double-layer steel mesh and spray C20 concrete to seal the air-side soil body (19) outside the side wall of the air shaft and air duct, excavate the soil body at the bottom of the demolished left-line tunnel segments to the structural bottom plate, and use C20 sprayed concrete and I22a steel supports for bottom sealing (20); (2)Construct the waterproof layer of the bottom slab, bind the steel bars, erect the scaffolding, and formwork and pour the secondary lining bottom slab structure within the range of the demolished segment linings. The secondary lining bottom slab structure is arranged in the free-standing soil mass (19) and the bottom seal (20), and then construct the side wall (8) and the ring beam (21) of the ventilation shaft air duct; After the segment linings of the left-line tunnel are demolished, demolish the segment linings of the right-line tunnel in the same way and construct the secondary lining structure of the ventilation shaft air duct within the range of the demolished segment linings to realize the connection between the ventilation shaft air duct and the left-line, right-line tunnels, No. 1 shaft, and No. 2 shaft.

2. A method for constructing the ventilation shaft air duct in a section of a shield tunnel segment demolished by the mining method as described in claim 1, characterized in that, In step one, the ventilation shaft air duct is set as a four-layer 12-pilot tunnel air duct. Excavate each chamber and construct the initial support in the order of the bench method according to the pilot tunnel numbers. The bench length is 3-5 meters. Timely install the locking foot anchor pipes. The longitudinal excavation lengths of each chamber are staggered by no less than 6 m; the upper pilot tunnels cross the existing tunnel and are excavated to the end wall for plugging, and construct end wall one A; the lower pilot tunnels are constructed to the outer edge of the left-line tunnel and then plugged, and construct end wall two B; When excavating the shaft in step three, block by block demolish the temporary inverted arches of the 2nd, 4th, and 6th upper pilot tunnels in the ventilation shaft air duct within the ranges of the No. 1 shaft opening and the No. 2 shaft opening. Timely erect the shaft grille, connect the longitudinal tie bars, and erect the steel support; the vertical excavation step distance is the grille spacing, and the vertical spacing of the steel support is the grille spacing; when excavating to the bottom of the shaft, timely seal the bottom; the construction should be carried out in the construction sequence of the No. 1 shaft first and then the No. 2 shaft. During the shaft construction process, deep-hole grouting reinforcement should be carried out on both sides of the shaft in a timely manner; When constructing the secondary lining bottom slab and part of the side wall of the ventilation shaft air duct in the shaft in step four, remove the lower two steel supports in the shaft, lay the waterproof layer, bind the steel bars, and pour the secondary lining bottom slab (14) and the lower part of the side wall; after the secondary lining bottom slab reaches 80% of the design strength, erect the scaffolding, locally demolish the temporary middle partition wall of the shaft, lay the waterproof layer, bind the steel bars, formwork and pour the upper part of the side wall (15) in the width direction of the ventilation shaft air duct and the upper part of the outer side wall (121) of the No. 2 shaft far from the tunnel and connect it to the middle partition board and the secondary lining structure of the underground first-layer track area.

3. A method for constructing the ventilation shaft air duct in a section of a shield tunnel segment demolished by the mining method as described in claim 1, characterized in that, The step of demolishing the segment linings in step five further includes the following steps: (1) Construction preparation steps: ① Erect a steel frame on the middle partition board of the ventilation shaft air duct, and lay 2 I32a steel beams (22) respectively at the top lifting openings (9) of the left-line tunnel and the top lifting openings (11) of the right-line tunnel. Fix 2 10t chain hoists on different steel beams respectively to facilitate the hoisting and external transportation of the segment linings and materials; ② Assemble the mobile steel ring support (18); Assemble the mobile steel ring support at the position of the segment lining to be demolished. The jacks in the hydraulic support system of the mobile steel ring support are radially symmetrically distributed. In the early stage, it can provide support stress for the segment linings with the connecting bolts removed. In the later stage, when demolishing the segment linings, the independent jacks can not only provide working space for the segment linings to be demolished by unloading the hydraulic rods, but also provide continuous support stress for the segment linings to be demolished, ensuring the overall stability of the segment linings to be demolished in the demolition ring; (2) Specific steps for segment demolition: ① First, demolish the middle segment, that is, demolish the first ring of segments ①. Erect the mobile steel ring support on the first ring of segments, and provide support stress to the segments through the hydraulic loading system of the mobile steel ring support; ② Drill through the grouting holes of the segments at the crown position, install the segment lifting bolts on the grouting holes of the segments to be demolished, and install these bolts on the lifting ropes of the chain hoists; Remove all the longitudinal connection bolts above the center line between the first ring of segments and the segments of the 2nd and 3rd rings on both sides; ③ Use a water drill or a wire saw machine to cut the first ring of wedge-shaped K-block segments at the crown. Make a cut around the K-block segments to remove the longitudinal jacking force of the segments, so that they are separated from the surrounding segments, and remove the K-block segments; During the demolition process, the jacks on both sides of the K-block segments of the mobile steel ring support are gradually unloaded, and the lifting ropes of the chain hoists are slowly tightened, and transported out of the tunnel through the reserved hoisting opening of the air shaft air duct; ④ Then demolish the adjacent segments. Install the segment lifting bolts in the bolt holes of the segments to be demolished, and remove the bolts connected to the adjacent segments; Slowly tighten the chain hoist, and the hydraulic jacks of the mobile steel ring support are symmetrically unloaded in segments, and the segments are hoisted out; Demolish the segments within 180° of the crown of the first ring of segments; ⑤ Use the same method as above to symmetrically demolish each ring in sequence from both sides of the first ring of segments; Demolish the segments within 180° of the crown of each ring of segments. Before demolition, a mobile steel ring support needs to be erected on this segment. After the segment demolition is completed, move the mobile steel ring support to the next ring of segments to be demolished; ⑥ Cut the segments within 180° of the bottom of the segments into small pieces with a water drill or a wire saw machine, and use an excavator to remove the divided and broken segments.

4. A method for demolishing the air shaft air duct in the construction section of a shield tunnel segment by the mining method as described in claim 1, characterized in that, the following reinforcement steps are also included before the excavation of the air shaft air duct: (1) Before the excavation of the air shaft air duct, remove the longitudinal connection bolts between the permanent segments and the segments to be demolished, and erect steel ring internal supports (16) with an outer diameter equal to the inner diameter of the segments on 10 rings of segments on both sides of the shield tunnel and inside the air shaft air duct. The steel rings are connected by I25b steel longitudinal connection beams (17) to prevent the increase of segment deformation during the construction process; (a) The steel ring is assembled and connected by arc-shaped steel plates. The steel ring is provided with two I40b double-rolled I-beam vertical supports (23) with a spacing of 2000 mm; Three I25b double-rolled I-beam horizontal supports (24) are provided. The first one is 1300 mm from the top; (b) Four I25b steel longitudinal connection beams (17) are provided at the cross centers of the upper, lower, left, and right of each steel ring for longitudinal connection between the steel rings; (2) Before the erection of the steel ring internal support, radial grouting reinforcement is carried out on the segment demolition section from inside the tunnel through the reserved grouting holes on the segments; Four rings of permanent segments on both sides of the air shaft air duct are grouted and reinforced from inside the tunnel to reinforce the surrounding strata of the segments. The radial grouting length is 2 m. Seven grouting holes are drilled in the upper part of each ring of segments and four grouting holes are drilled in the lower part; The grouting slurry adopts single-component cement slurry. During the grouting operation, the changes in grouting pressure and flow rate should be observed, and the grouting parameters should be strictly controlled; (3) Auxiliary grouting reinforcement in the shaft and the pilot tunnel of the air duct Before the segment demolition, grouting reinforcement is carried out on the surrounding soil of the adjacent 4-ring segments on both sides of the ventilation shaft air duct. At the lower pilot tunnel near the end wall 2B, grouting holes are drilled from the primary support of the lower pilot tunnel of the ventilation shaft air duct for reinforcement. The horizontal spacing of the grouting holes is 1m, the vertical spacing is 1m, and they are arranged in a plum blossom shape, with a drilling length of 4m. Near the shaft, when the primary support is constructed in the shaft, grouting holes are horizontally drilled for reinforcement. The horizontal spacing of the grouting holes is 1m, the vertical spacing is 1m, and they are arranged in a plum blossom shape, with a drilling length of 4m. The grout used is single-component cement slurry. During the grouting process, the grouting parameters are strictly controlled to ensure that the diffusion range of the grout radius reaches 0.5m, and the grout between the grouting holes can effectively overlap.

5. An interval ventilation shaft air duct constructed by the mining method for demolishing shield tunnel segments, including an existing tunnel, and the existing tunnel includes a left-line tunnel and a right-line tunnel. It is characterized in that it further includes the underground first floor (1) and the underground second floor (2) of the ventilation shaft air duct constructed by the pilot tunnel bench method; the underground first floor transversely crosses the two existing tunnels above the tops of the left and right line tunnels and constructs the primary support until the end wall of the ventilation shaft air duct is blocked, and end wall 1A is set; the underground second floor transversely reaches the outer edge of the adjacent left-line tunnel below the tunnel top for blocking, and end wall 2B is set, and the primary support is constructed; a No. 1 shaft (100) is arranged between the left and right line tunnels, and a No. 2 shaft (120) is arranged on the side of the right-line tunnel, and the primary support is constructed; a No. 1 shaft opening (10) and a No. 2 shaft opening (12) are set on the middle partition of the underground first floor (1); within the range of the ventilation shaft air duct, the end wall 2B, the left-line tunnel segments, the primary support of the side wall of the No. 1 shaft, the right-line tunnel segments, and the primary support of the side wall of the No. 2 shaft are synchronously demolished to connect the ventilation shaft air duct with the left and right line tunnels, the No. 1 shaft, and the No. 2 shaft.

6. An interval ventilation shaft air duct constructed by the mining method for demolishing shield tunnel segments according to claim 5. It is characterized in that the underground first floor (1), the underground second floor (2), the demolition ranges of the left-line tunnel segments and the right-line tunnel segments, and the No. 1 shaft and the No. 2 shaft are provided with a secondary lining structure.

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