Method for sealing underwater tunnel entrances for tunnel boring machines

Abstract

This invention discloses a method for sealing underwater tunnel portals for tunnel boring machines (TBMs), comprising the following steps: 1. If leakage occurs during TBM entry, immediately refill the TBM receiving shaft with water up to the pressurized water level; 2. Grout the ground in the tunnel construction area; 3. Reinforce the tunnel interior; 4. Install steel rings (9) on the tunnel segments (41) with large misalignments for reinforcement; 5. Remove the steel pipe support system inside the tunnel (4) and carry out TBM re-pushing construction; 6. After the TBM is re-pushed into place, perform underwater portal sealing welding; 7. Pump water into the TBM receiving shaft and perform portal sealing reinforcement welding; 8. After the portal sealing reinforcement is completed, inject single-liquid grout into the portal and backfill with cement mortar; 9. During the shield cutting operation, weld and seal the exposed grease pipes and synchronous grouting pipes at the shield tail with iron plates. This invention can prevent tunnel portal leakage during TBM entry and improve construction safety.

Description

Technical Field

[0001] This invention relates to a method for tunnel boring machine (TBM) entry construction, and more particularly to a method for sealing underwater tunnel entrances for TBM entry. Background Technology

[0002] In the construction of subway tunnels using the shield tunneling method, the shield machine often faces the risk of leakage when entering the tunnel, especially when the tunnel section is located in adverse geological conditions. Currently, the conventional methods for receiving the shield machine upon entering the tunnel include steel base reception, underwater reception, and foamed concrete reception.

[0003] If leakage occurs during the tunnel boring machine's (TBM) entry and reception, conventional steel foundations are relatively passive in dealing with leakage risks and cannot proactively address them in a timely manner. Ground grouting and other solutions are limited by the traffic conditions above the tunnel and have a long response time. While underwater reception and foamed concrete reception can balance water and soil pressure through rapid water reinjection, there is still a certain risk of leakage when conventional dewatering is used to seal the tunnel entrance, potentially leading to leakage at the tunnel entrance during TBM entry.

[0004] During the secondary reception of the tunnel boring machine (TBM), existing construction techniques pose a significant risk of leakage at the tunnel portal, leading to soil erosion, severe deformation of the surface and tunnel structure, and even serious production accidents. Therefore, a tunnel portal sealing method is needed to effectively address leakage during TBM entry. Summary of the Invention

[0005] The purpose of this invention is to provide a method for sealing underwater tunnel entrances for tunnel boring machines (TBMs), which can prevent leakage at the tunnel entrances during TBM entry and improve construction safety.

[0006] This invention is implemented as follows:

[0007] A method for sealing underwater tunnel entrances for tunnel boring machines includes the following steps:

[0008] Step 1: If serious leakage occurs when the tunnel boring machine enters the tunnel, immediately reinject water into the receiving shaft of the tunnel boring machine. The water level of the reinjected water should be the same as the water level of the pressurized water to balance the water pressure inside and outside the receiving shaft of the tunnel boring machine.

[0009] Step 2: Grouting is carried out on the ground in the tunnel construction area. The grouting includes shallow filling grouting at the top of the tunnel and deep micro-disturbance grouting on both sides of the tunnel.

[0010] Step 3: Reinforce the interior of the tunnel, which includes polyurethane injection, support system installation, shield machine shell grouting, and tunnel bottom micro-disturbance grouting.

[0011] Step 4: Before the tunnel boring machine pushes the tunnel again, install steel rings across the joints of the tunnel segments with large misalignments for reinforcement;

[0012] Step 5: Dismantle the steel pipe support system inside the tunnel and carry out the shield machine re-pushing operation;

[0013] Step 6: After the tunnel boring machine is pushed back into place, underwater portal sealing welding is carried out;

[0014] Step 7: Pump water out of the tunnel boring machine receiving shaft and reinforce and weld the tunnel portal.

[0015] Step 8: After the tunnel portal is sealed and reinforced, inject single-component grout into the portal and backfill with cement mortar;

[0016] Step 9: After the grout from Step 8 has initially set, the shield cutting operation is carried out. After the cutting is completed, the grease pipes and synchronous grouting pipes exposed at the tail of the shield are welded and sealed with iron plates. After the sealing is completed, the shield machine reception is fully completed.

[0017] The construction method for shallow filling grouting at the top of the tunnel is as follows:

[0018] Shallow single-liquid grouting is carried out in the area of ​​large surface settlement corresponding to the shield machine receiving shaft. Multiple rows of second grouting holes for cement grout filling are drilled on the concrete pavement outside the shield machine receiving shaft enclosure. The drilling depth of the second grouting holes is consistent with the roadbed thickness. Cement grout is filled into the second grouting holes to fill the gap between the roadbed and the original soil.

[0019] The construction method for deep micro-disturbance grouting on both sides of the tunnel is as follows:

[0020] Deep micro-disturbance grouting is carried out on both sides above the tunnel near the leakage point. The third grouting holes of the deep micro-disturbance are arranged on the left and right sides of the tunnel edge, and the third grouting holes on the left and right sides are arranged in parallel and symmetrically. The grouting depth of the deep micro-disturbance grouting is from below the bottom surface of the tunnel structure to above the bottom surface of the tunnel structure.

[0021] The polyurethane injection construction method is as follows: polyurethane is injected into the bottom of the tunnel in the shield machine receiving section to seal the water leakage channels of the tunnel portal and the formed tunnel segments.

[0022] The installation of the support system includes the following steps:

[0023] Step S1: Install the support steel pipe. The support steel pipe is installed inside the tunnel boring machine receiving section. The support steel pipe includes one horizontal support and two vertical supports. The two vertical supports are symmetrically arranged about the longitudinal centerline of the tunnel. The horizontal support is perpendicularly connected to the two vertical supports and is located below the transverse centerline of the tunnel. Diagonal supports are added at tunnel segments with large misalignments.

[0024] Step S2: In the receiving section of the tunnel boring machine, a segment connecting plate is installed between adjacent tunnel segments, and the segment connecting plates are welded together to form an integral structure by tie rods;

[0025] Step S3: Install several tunnel tie rods on the outside of the tunnel segments. The tunnel tie rods are fixedly connected to the tunnel segments through the tie rod base plate and the rebar. Auxiliary tie rods are added between the tunnel segments with large misalignment and the tunnel tie rods.

[0026] The construction method for grouting the shield machine shell is as follows:

[0027] Two sets of grouting holes are configured on the tunnel segments: multiple A-ring shell grouting holes spaced apart on both sides of the A-ring at the front shield of the tunnel boring machine, and multiple articulated shield tail grouting holes located at the tail of the tunnel boring machine and arranged circumferentially. Each A-ring shell grouting hole and articulated shield tail grouting hole is equipped with a grouting ball valve. Before the tunnel boring machine pushes back up, except for the articulated shield tail grouting hole located at the top of the tunnel segment, ring clamp grouting is performed through multiple A-ring shell grouting holes and the remaining articulated shield tail grouting holes. After the clamp grouting, the grouting ball valve is kept unobstructed for secondary ring clamp grouting during the tunnel boring machine push-back stage.

[0028] The installation method of the steel ring with the seam is as follows:

[0029] Install brackets on the misaligned tunnel segments. Level the brackets with the tunnel segments of the next ring following the misaligned tunnel segment, so that the joint steel ring can be circumferentially connected between the brackets and the tunnel segments of the next ring following the misaligned tunnel segment. The joint steel ring is also circumferentially connected between the misaligned tunnel segment and the tunnel segments of the previous ring.

[0030] Step 6 includes the following sub-steps:

[0031] Step 6.1: Before receiving the tunnel boring machine, weld an arc-shaped steel ring to the bottom of the tunnel boring machine shell;

[0032] Step 6.2: Following the order from bottom to top and from left to right, weld arc-shaped steel plates onto the shield machine shell. Several arc-shaped steel plates located at the bottom of the shield machine shell are welded and fixed to the arc-shaped steel ring.

[0033] Step 6.3: Weld multiple triangular precision plates onto each curved steel plate.

[0034] Step 7 includes the following sub-steps:

[0035] Step 7.1: Pumping test. If all leakage channels are reliably sealed, proceed to step 7.2. If the leakage channels are not reliably sealed, perform ring grouting on the tunnel.

[0036] Step 7.2: Weld sealing plates from top to bottom to reinforce the opening.

[0037] Step 7.1 includes the following sub-steps:

[0038] Step 7.1.1: Pump water into the tunnel boring machine receiving shaft to lower the water level to 1m below the original soil water level. Stop pumping for 2-3 hours and observe the water level change in the shaft, and plot the water level change curve. If the water level curve does not rise, the seepage channel above the water surface is reliably blocked, and proceed to step 7.1.2. If the water level changes significantly and the seepage channel above the water surface is not reliably blocked, immediately recharge the water level to the original water level before pumping, and perform ring grouting in the tunnel.

[0039] Step 7.1.2: Lower the water level in the tunnel boring machine receiving shaft by another 1m and continue to observe the water level in the shaft for 2-3 hours, and draw a water level curve; if the water level curve remains stable, that is, the seepage channel above the water surface is reliably blocked, proceed to step 7.1.3; if the water level changes significantly and the seepage channel above the water surface is not reliably blocked, immediately recharge the water level to the original water level before pumping, and carry out ring grouting work in the tunnel;

[0040] Step 7.1.3: Lower the water level in the tunnel boring machine receiving shaft by another 1m, and observe the water level in the shaft for 2-3 hours. If the water level remains stable, all seepage channels are reliably sealed. If the water level changes significantly and the seepage channels above the water surface are not reliably sealed, immediately recharge the water level to the original water level before pumping, and carry out ring grouting work in the tunnel.

[0041] Step 7.1.4: Repeat step 7.1.3 until the water level stabilizes and the pumping test is passed;

[0042] Step 7.2 includes the following sub-steps:

[0043] Step 7.2.1: Pump the water in the receiving shaft of the tunnel boring machine to a level that meets the requirements for the welding space of the first sealing plate, and weld the first sealing plate to seal and reinforce the tunnel entrance;

[0044] Step 7.2.2: Pump water again until it meets the requirements below the second and third sealing plates and the welding space requirements for the second and third sealing plates. Weld the second and third sealing plates to seal and reinforce the opening.

[0045] Step 7.2.3: Repeat step 7.2.2, pumping water while welding the sealing plates, until all sealing plates are welded and the opening is sealed and reinforced;

[0046] Step 7.2.4: Seal the gap between the shield machine shell and the sealing plate with double-fast cement, and at the same time reserve grouting holes and install grouting ball valves at the arc-shaped steel plate.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] 1. This invention reinforces the ground inside the tunnel and the tunnel construction area before the tunnel boring machine (TBM) is pushed back into the tunnel. This effectively avoids problems such as soil erosion, deformation of the surface and tunnel structure, and loss of construction personnel and equipment caused by leakage when the TBM enters the tunnel. It also avoids the risk of leakage during the tunnel entrance sealing process when the TBM enters the tunnel in water, thus improving the safety of the TBM receiving process.

[0049] 2. This invention employs an underwater tunnel portal sealing process. By conducting pumping tests to determine whether all leakage channels are reliably sealed, the water level is gradually lowered and the tunnel portal is simultaneously sealed and reinforced through a method of pumping water and sealing simultaneously. At the same time, the water level inside the well is monitored in real time, and the welding of the tunnel portal sealing plate is reliable and safe. In the event of severe leakage when the tunnel boring machine enters the tunnel under adverse geological conditions, underwater tunnel portal sealing can provide a safe and effective guarantee for construction.

[0050] 3. This invention pumps water from the tunnel boring machine receiving shaft between the left and right lines during underwater tunnel portal sealing construction. This allows for timely backfilling of the receiving shaft in case of leakage and prompt grouting reinforcement and sealing. This approach quickly and effectively addresses the risk of leakage, minimizing it and solving the problem of leakage during tunnel boring machine entry. Attached Figure Description

[0051] Figure 1 This is a construction schematic diagram of shallow single-liquid grout injection in the underwater tunnel portal sealing method for tunnel boring machines of the present invention; in the figure, "340", "345", "350", "355", "360", "365", "370", and "335" are the number of rings of the tunnel segments;

[0052] Figure 2 This is a construction schematic diagram of cement grout filling in the underwater tunnel portal sealing method for tunnel boring machines according to the present invention; in the figure, "340", "345", "350", "355", "360", "365", "370", and "335" are the number of rings of the tunnel segments;

[0053] Figure 3 This is a construction schematic diagram of deep micro-disturbance grouting on both sides of the tunnel in the underwater tunnel portal sealing method for tunnel boring machines of the present invention;

[0054] Figure 4 This is a construction diagram of the supporting steel pipe in the underwater tunnel portal sealing method for tunnel boring machines of the present invention;

[0055] Figure 5This is a construction schematic diagram of the tunnel tie rod in the underwater tunnel portal sealing method for tunnel boring machine entry of the present invention; in the figure, "360", "359", "358", "357", "356", "355", and "354" are the number of rings of the tunnel segments;

[0056] Figure 6 This is a schematic diagram showing the distribution of grouting holes in the A-ring shell of the present invention for sealing the underwater tunnel entrance of a tunnel boring machine;

[0057] Figure 7 This is a schematic diagram showing the distribution of the grouting holes at the tail of the shield in the underwater tunnel portal sealing method for tunnel boring machines of the present invention;

[0058] Figure 8 This is a construction schematic diagram of the tunnel bottom micro-disturbance grouting in the underwater tunnel portal sealing method for tunnel boring machine entry of the present invention;

[0059] Figure 9 This is a construction schematic diagram of the steel rings slabs in the underwater tunnel portal sealing method for tunnel boring machines according to the present invention; in the diagram, "356", "357", and "358" represent the number of rings in the tunnel segments;

[0060] Figure 10 This is a schematic diagram of the underwater tunnel portal sealing and reinforcement method for tunnel boring machine entry in this invention;

[0061] Figure 11 This is a construction schematic diagram of the sealing plate in the underwater tunnel portal sealing method for tunnel boring machines according to the present invention.

[0062] In the diagram, 1 is the first grouting hole, 2 is the second grouting hole, 3 is the third grouting hole, 4 is the tunnel, 41 is the tunnel segment, 42 is the corbel, 43 is the grouting hole of the A ring shell, 44 is the grouting hole of the hinged shield tail, 5 is the transverse support, 6 is the vertical support, 7 is the tunnel tie rod, 8 is the auxiliary tie rod, 9 is the steel ring across the joint, 10 is the arc-shaped steel ring, 11 is the arc-shaped steel plate, 12 is the shield machine shell, 13 is the channel steel, 14 is the sealing wall, and 15 is the sealing plate. Detailed Implementation

[0063] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0064] A method for sealing underwater tunnel entrances for tunnel boring machines includes the following steps:

[0065] Step 1: If serious leakage occurs when the tunnel boring machine enters the tunnel, immediately reinject water into the receiving shaft of the tunnel boring machine. The water level of the reinjected water should be the same as the water level of the pressurized water to balance the water pressure inside and outside the receiving shaft of the tunnel boring machine.

[0066] When serious leakage occurs during the tunnel boring machine's entry into the tunnel, the leakage problem at the tunnel entrance can be quickly addressed by balancing the water pressure inside and outside the reinjection water well, reducing the duration of continuous leakage around the tunnel entrance.

[0067] Step 2: Grout the ground in the tunnel construction area.

[0068] The grouting includes shallow filling grouting at the top of the tunnel and deep micro-disturbance grouting on both sides of the tunnel.

[0069] The construction method for shallow filling grouting at the top of the tunnel is as follows:

[0070] Please see the appendix Figure 1 Shallow single-component grouting was carried out in the area of ​​significant surface settlement (cumulative settlement exceeding 5cm) corresponding to the tunnel boring machine receiving shaft. The drilling depth of the first grouting hole 1 for shallow single-component grouting was 4m; please refer to the attached document. Figure 2 Multiple rows of second grouting holes 2 are drilled on the concrete pavement outside the shield machine receiving shaft for cement grout filling. The drilling depth of the second grouting holes 2 is consistent with the roadbed thickness. For example, if the roadbed thickness is 40cm, the drilling depth of the second grouting holes 2 is 0.4m. Two rows of second grouting holes 2 can be drilled. Cement grout filling is carried out in the second grouting holes 2 to fill the gap between the roadbed and the original soil.

[0071] The construction method for deep micro-disturbance grouting on both sides of the tunnel is as follows:

[0072] Please see the appendix Figure 3 Deep micro-disturbance grouting is performed on both sides above the leakage point of tunnel 4. The third grouting holes 3 for deep micro-disturbance grouting are arranged in a planar manner 1-2m outside the tunnel edge on both sides, and the third grouting holes 3 on the left and right sides are arranged in parallel and symmetrically, for a total of 2 rows of third grouting holes 3. The number of third grouting holes 3 can be adjusted according to the actual situation, preferably 30 holes. The grouting depth of deep micro-disturbance grouting is from 3m below the structural bottom surface of tunnel 4 to 1m above the structural bottom surface of tunnel 4.

[0073] Step 3: Reinforce the interior of the tunnel.

[0074] The tunnel interior reinforcement includes polyurethane injection, support system installation, shield machine shell grouting, and tunnel bottom micro-disturbance grouting.

[0075] The polyurethane injection construction method is as follows: polyurethane is injected into the bottom of the tunnel in the shield machine receiving section to seal the water leakage channels of the tunnel portal and the formed tunnel segments, fill the seepage channels, and prevent further soil loss.

[0076] The installation of the support system includes the following steps:

[0077] Step S1: Install the supporting steel pipe.

[0078] Please see the appendix Figure 4The supporting steel pipe is installed in the receiving section of the tunnel boring machine. The supporting steel pipe includes one horizontal support 5 and two vertical supports 6. The two vertical supports 5 are symmetrically arranged about the longitudinal centerline of the tunnel 4. The horizontal support 5 is perpendicularly connected to the two vertical supports 6 and is located below the horizontal centerline of the tunnel 4. At the same time, the bridge frame (i.e. the part where the shield body and the frame are connected) and the tunnel segments 41 above the frame are vertically and symmetrically connected to the bridge frame or the frame through H-beams.

[0079] An oblique support (not shown in the figure) is installed at the tunnel segment 41 with a large misalignment (more than 3 cm). One end of the oblique support is supported on the misaligned part, and the other end of the oblique support is supported on the fixed member on the opposite side of the misaligned part, so as to provide support for the tunnel segment 41 with a large misalignment.

[0080] Preferably, both the transverse support 5 and the two vertical supports 6 can be made of 4-inch ordinary steel pipes. The tunnel segments 41 of the 353rd to 360th rings are the receiving sections of the tunnel boring machine, and a set of steel pipe support systems can be installed in each ring of the tunnel segments 41 of the 353rd to 360th rings; if the misalignment of the tunnel segments 41 of the 356th to 357th rings is large, diagonal supports can be added in the tunnel segments 41 of the 356th to 357th rings to slow down the convergence deformation rate of the formed tunnel and stabilize the formed tunnel structure.

[0081] Step S2: In the receiving section of the tunnel boring machine, a segment connecting plate is installed between two adjacent rings of tunnel segments 41. The segment connecting plates are welded together by tie rods to form an integral structure, which is used to further strengthen the stability of the formed tunnel segments 41.

[0082] Preferably, the segment connecting plate can be made of 30*30*2cm steel plate. In some cases, 30*50*2cm steel plate can also be used as the segment connecting plate between tunnel segments 41. The segment connecting plate is placed at the connection point of adjacent tunnel segments 41.

[0083] Please see the appendix Figure 5 Step S3: Install several tunnel tie rods 7 on the outside of the tunnel segment 41. The tunnel tie rods 7 are fixedly connected to the tunnel segment 41 through the tie rod base plate 71 and the rebar 72. Auxiliary tie rods 8 are added between the tunnel segment 41 and the tunnel tie rod 7 where the misalignment is large (more than 3cm).

[0084] The aforementioned tunnel tie rods 7 are arranged symmetrically along the circumference of the tunnel segment 41. The length direction of the tunnel tie rods 7 is parallel to the axial direction of the tunnel 4, and both ends of the tunnel tie rods 7 extend to the outer ends of the shield machine receiving section. The auxiliary tie rods 8 are arranged radially along the tunnel segment 41. Since the 353rd to 360th ring of tunnel segment 41 is the shield machine receiving section, the installation range of the tie rods 8 can be the 348th to 362nd ring of tunnel segment 41, preferably 6 tunnel tie rods 7.

[0085] Preferably, the tunnel tie rod 7 can be fixed by bolts. Depending on the site conditions, 20# I-beams or 10# channel steel can be selected as the tunnel tie rod 7, and 20# I-beams can be selected as auxiliary tie rods 8. Multiple I-beams and channel steels are spliced ​​together to form the tunnel tie rod 7 to meet its installation length requirements. Each I-beam and channel steel can connect 5-10 rings of tunnel segments 41. The tie rod base plate 71 can be made of 60*50*2cm steel plate, and the rebar 72 can be made of 2.5cm diameter steel bars, with a spacing of 15cm and a depth of 15cm. During the tunnel boring machine's re-pushing, the tunnel tie rods 7 and auxiliary tie rods 8 can play a role in transmitting thrust. In this area, the tunnel segments 41 of the 360th and 359th rings, which are directly connected to the tunnel tie rods 7, bear the force. The force is transmitted to the tunnel segments 41 of the 356th, 355th, etc. rings connected by the auxiliary tie rods 8 through the connection of the tunnel tie rods 7, so as to reduce the force on the tunnel segments 41 with larger misalignment.

[0086] The construction method for grouting the shield machine shell is as follows:

[0087] Please see the appendix Figure 6 and attached Figure 7 Two sets of grouting holes are configured on the tunnel segment 41: multiple A-ring shell grouting holes 43 are arranged at intervals along both sides of the A-ring located at the front shield of the tunnel boring machine, and multiple articulated shield tail grouting holes 44 are arranged circumferentially at the tail of the tunnel boring machine. Each A-ring shell grouting hole 43 and articulated shield tail grouting hole is equipped with a grouting ball valve. Before the tunnel boring machine is pushed back up, except for the articulated shield tail grouting hole located at the top of the tunnel segment 41, ring clamping grouting is performed through multiple A-ring shell grouting holes 43 and the remaining articulated shield tail grouting holes 44. After the clamping grouting, the grouting ball valve is kept unobstructed so that secondary ring clamping grouting can be performed during the tunnel boring machine push-back stage.

[0088] Preferably, there are 6 grouting holes 43 in the A-ring shell and 10 grouting holes in the hinged shield tail. The grouting holes 43 in the A-ring shell and the grouting holes in the hinged shield tail can utilize the grouting holes on the tunnel segment 41 itself, and the remaining grouting holes 43 in the A-ring shell and the grouting holes in the hinged shield tail can be opened at intervals on the tunnel segment 41 according to the construction conditions. The tunnel segment 41 has three grouting holes at the A-ring, so three more grouting holes 43 in the A-ring can be added. The tunnel segment 41 at the tail of the shield machine has four grouting holes, so six more grouting holes in the hinged shield tail can be added.

[0089] Preferably, the ring clamp grouting can be performed using polyurethane circulating skip-hole grouting, with 100 kg injected into each of the A-ring shell grouting holes 43 and the hinged shield tail grouting holes to observe the grouting effect.

[0090] During the secondary ring grouting in the tunnel boring machine's second push phase, the water-cement ratio of the cement grout was 1:1, the volume ratio of cement grout to water glass was 1:2, and the setting time was 15 seconds. Grouting technical requirements: single-hole injection volume 0.5m. 3 The grouting pressure should not exceed 0.4 MPa. During secondary ring grouting, a dual-control mode of pressure and injection volume is implemented, meaning the injection volume reaches 0.5 m... 3 If the pressure does not exceed the requirement, continue injection until the pressure reaches 0.4 MPa; if the injection volume does not reach 0.5 m³, continue injection until the pressure reaches 0.4 MPa. 3 However, once the grouting pressure has reached the required level, the single-hole grouting is completed, and the tunnel deformation should be closely monitored during the secondary ring grouting process.

[0091] The construction method of the tunnel bottom micro-disturbance grouting is as follows:

[0092] Please see the appendix Figure 8 In tunnels where leakage occurs, micro-disturbance grouting is performed on the bottom of tunnel segments 41 of rings 344-358 with significant misalignment (more than 3cm). If leakage occurs at the tunnel portal during the left-line shield receiving process, causing soil loss, micro-disturbance grouting is required on the bottom of tunnel segments 41 with significant misalignment to strengthen the bearing capacity of the segment bottom. The tunnel bottom micro-disturbance grouting uses three articulated shield tail grouting holes within the bottom range of a single-ring tunnel segment 41 to perform deep filling grouting within a 3m area below the tunnel segment 41. A single-liquid grout can be used to enhance the bearing capacity of the soil at the bottom of the tunnel, stabilize the formed tunnel structure, and prevent later settlement.

[0093] Please see the appendix Figure 9 Step 4: Before the tunnel boring machine pushes the shield back up, install steel rings 9 across the joints of the tunnel segments 41 with large misalignments for reinforcement.

[0094] Due to leakage, the misalignment of segment 41 of the 357th ring tunnel is relatively large, reaching 18cm with that of segment 41 of the 358th ring tunnel. A steel ring 9 is installed between segment 41 of the 358th ring tunnel and segment 41 of the 357th ring tunnel. The installation method of the steel ring 9 is as follows:

[0095] A bracket 42 is installed on the misaligned tunnel segment 41 (i.e., the 357th ring tunnel segment 41). The bracket 42 is leveled with the tunnel segment 41 of the next ring after the misaligned tunnel segment 41 (i.e., the 358th ring tunnel segment 41), so that the joint steel ring 9 can be circumferentially connected between the bracket 42 and the tunnel segment 41 of the next ring after the misaligned tunnel segment 41 (i.e., the 358th ring tunnel segment 41), and the joint steel ring 9 is circumferentially connected between the misaligned tunnel segment 41 and the tunnel segment 41 of the previous ring (i.e., the 356th ring tunnel segment 41).

[0096] Preferably, the joint-spanning steel ring 9 can be made of steel with a thickness of 3cm and a width of 90cm. The inner diameter of the joint-spanning steel ring 9 is determined according to the outer diameter of the tunnel segment 41 at its installation position. The joint-spanning steel ring 9 is continuously and fully welded to the tunnel segment 41. The bracket 42 is fixed to the tunnel segment 41 by rebar anchoring, and the bracket 42 is filled with epoxy mortar.

[0097] Step 5: Inspect the quality of the grout from Step 4. Once the grout quality is deemed acceptable, dismantle the steel pipe support system inside Tunnel 4 and proceed with the tunnel boring machine's re-pushing operation.

[0098] During the tunnel boring machine's repeated pushing operation, the factors that need to be controlled include:

[0099] Inside tunnel 4: a) During the advancement process, the arch bottom of the formed segments 41 (such as tunnel segments 41 of rings 345-362) converges in the receiving section and before and after it;

[0100] b. Misalignment between tunnel segments 41;

[0101] c. Over-injection of grease at the shield tail, 60kg per ring;

[0102] d. The tunnel boring machine maintains a ramp-up advance, with the elevation controlled above -30mm;

[0103] e. The number of rings that have come off the shield tail should be connected in a timely manner with tie rods made of 14# channel steel;

[0104] f. Perform mud-controlling, synchronous grouting, dual-liquid grouting, and polyurethane pressure injection work inside the tunnel.

[0105] Inside the tunnel boring machine receiving shaft: a) monitor the water level inside the shaft; b) monitor surface settlement every 4 hours; c) keep records of pumping tests.

[0106] Step 6: After the tunnel boring machine is pushed back into place, two divers will perform real-time underwater portal sealing welding.

[0107] The construction equipment for underwater tunnel portal sealing and welding includes: 300m 3 / h water pump and 3 150m 3 / h mud pump, SGⅢ type underwater oxy-acetylene torch, BR-21 underwater welding equipment wet welding torch, and diving equipment (0.6m) 3 One diesel air compressor, two diving suits, a breathing apparatus, two sets of oxygen tubing, one underwater walkie-talkie, etc.

[0108] The tunnel boring machine (TBM) re-pushing is a routine construction procedure in TBM construction and can be carried out using existing construction techniques, so it will not be elaborated here. After the TBM receiving shaft is cleaned of polyurethane, silt, and extension track, the underwater portal can be sealed, following a bottom-up sealing principle. The sealing process is carried out by two divers simultaneously: one diver performs the sealing work by welding the sealing plate around the tunnel lining, and the other diver assists in fixing the sealing plate. The specific construction method is as follows:

[0109] Please see the appendix Figure 10 Step 6 includes the following sub-steps:

[0110] Step 6.1: Before the tunnel boring machine is received, weld an arc-shaped steel ring 10 to the bottom of the tunnel boring machine shell 12.

[0111] Preferably, the arc-shaped steel ring 10 protrudes 5cm from the hole in the shield machine shell 12 and leaves a gap of about 2cm between it and the bottom of the tunnel segment 41. The arc-shaped steel ring 10 is a steel ring with a width of 5cm and an arc length of 3.6m, and the bottom of the shield machine shell 12 is welded and fixed to the arc-shaped steel ring 10 in one go.

[0112] Step 6.2: Following the order from bottom to top and from left to right, weld the arc-shaped steel plates 11 onto the shield machine shell 12. Several arc-shaped steel plates 11 located at the bottom of the shield machine shell 12 are welded and fixed to the arc-shaped steel rings 10.

[0113] Preferably, the arc-shaped steel plate 11 is made of steel plate with a width of 30cm and an arc length of 1.24m. The three arc-shaped steel plates 11 located at the bottom of the shield machine shell 12 are welded and fixed to the arc-shaped steel ring 10. The arc-shaped structure of the arc-shaped steel ring 10 facilitates the welding and positioning of the arc-shaped steel ring 10, so that the arc-shaped steel ring 10 is circumferentially welded to the shield machine shell 12.

[0114] Step 6.3: Weld multiple triangular precision plates (not shown in the figure) onto each arc-shaped steel plate 11. Preferably, the size of the triangular precision plates is 10*10*2cm to increase the compressive strength of the arc-shaped steel plate 11. The number of triangular precision plates can be increased or decreased according to actual needs.

[0115] Inspect all welds to ensure welding reliability before proceeding to step 7.

[0116] Step 7: Pump water out of the tunnel boring machine receiving shaft and reinforce and weld the tunnel portal.

[0117] Step 7 includes the following sub-steps:

[0118] Step 7.1: Pumping test. If all leakage channels are reliably sealed, proceed to step 7.2. If the leakage channels are not reliably sealed, perform ring grouting on tunnel 4, which is the shield machine shell grouting in step 3.

[0119] Step 7.1 includes the following sub-steps:

[0120] Step 7.1.1: Pump water from the tunnel boring machine receiving shaft until the water level drops to 1m below the original soil water level. Stop pumping for 2-3 hours and observe the water level changes. Record the water level changes every 5 minutes and plot the water level change curve. If the water level curve shows no upward movement, the seepage channel above the water surface is reliably sealed, proceed to step 7.1.2. If the water level changes significantly and the seepage channel above the water surface is not reliably sealed, immediately recharge the water to the original water level before pumping, and perform ring grouting in tunnel 4.

[0121] Step 7.1.2: Lower the water level in the tunnel boring machine receiving shaft by another 1m and continue to observe the water level for 2-3 hours. Record the water level change every 5 minutes and plot the water level curve. If the water level curve remains stable, meaning the seepage channel above the water surface is reliably sealed, proceed to step 7.1.3; if the water level changes significantly and the seepage channel above the water surface is not reliably sealed, immediately recharge the water level to the original water level before pumping (i.e., 1m lower than the original soil water level in step 7.1.1), and perform ring grouting work inside tunnel 4.

[0122] Step 7.1.3: Lower the water level in the tunnel boring machine receiving shaft by another 1m, and observe the water level for 2-3 hours. Record the water level change every 5 minutes. If the water level remains stable, all seepage channels are reliably sealed. If the water level changes significantly and the seepage channels above the water surface are not reliably sealed, immediately recharge the water level to the original water level before pumping (i.e., 2m lower than the original soil water level), and perform ring grouting in tunnel 4.

[0123] Step 7.1.4: Repeat step 7.1.3 until the water level stabilizes and the pumping test is passed.

[0124] Preferably, during the dewatering test of the left-line tunnel, water in the left-line shield machine receiving shaft can be pumped to the right-line shield machine receiving shaft. Prior to this, four water pumps should be installed in the right-line shield machine receiving shaft and connected to the pipelines. If there is a significant change in the water level in the left-line shield machine receiving shaft, the water in the right-line shield machine receiving shaft should be immediately reinjected into the left-line shield machine receiving shaft. Simultaneously, the left-line tunnel should be grouted again.

[0125] Step 7.2: Weld sealing plates from top to bottom to reinforce the opening.

[0126] Please see the appendix Figure 11 Step 7.2 includes the following sub-steps:

[0127] Step 7.2.1: Pump the water in the receiving shaft of the tunnel boring machine to a level that meets the requirements for welding construction space for the first sealing plate 15 (i.e., the sealing plate at the top of the tunnel portal), and weld the first sealing plate 15 to seal and reinforce the tunnel portal.

[0128] Preferably, when welding the sealing plate 15 on the upper part of the tunnel portal, after the top of the tunnel boring machine emerges from the water, the construction personnel can be transported to the top of the tunnel boring machine in the form of a basket, secured with safety belts, and the construction personnel can go to the top of the tunnel boring machine to carry out the tunnel portal sealing operation of the first sealing plate.

[0129] Step 7.2.2: Pump water again until it is below the second sealing plate 15 and the third sealing plate 15 (i.e., the two adjacent sealing plates on both sides of the first sealing plate), and meet the welding construction space requirements of the second sealing plate 15 and the third sealing plate 15. Weld the second sealing plate 15 and the third sealing plate 15 to seal and reinforce the opening.

[0130] Step 7.2.3: Repeat step 7.2.2, while pumping water, weld the sealing plate 15 until all sealing plates 15 are welded, and seal and reinforce the opening.

[0131] Preferably, after each subsequent rainfall reaches the sealable construction liquid level, a 2m long No. 14 channel steel 13 is welded on each of the left and right sides of the interface between the liquid level and the tunnel boring machine to provide a standing platform for welders. For welding below the waist of the tunnel boring machine shell 12, wooden ladders can be placed between the sides of the tunnel boring machine shell 12 and the sealing wall 14 to provide a standing platform for welders.

[0132] Step 7.2.4: Seal the gap between the shield machine shell 12 and the sealing plate 15 with double-fast cement, and at the same time reserve 6 grouting holes at the arc-shaped steel plate 11 and install grouting ball valves.

[0133] Step 8: After the tunnel portal is sealed and reinforced, single-liquid grout is injected into the tunnel portal through 6 reserved grouting ball valves to further reinforce the sealing. At the same time, the remaining freezing pipes are removed and the 6 reserved grouting holes are backfilled with cement mortar.

[0134] Step 9: After the grout from Step 8 has initially set, the shield cutting operation will be carried out. The cutting location is 10 cm outside the tunnel ring. After the cutting is completed, the grease pipe and synchronous grouting pipe exposed at the shield tail will be welded and sealed with iron plates. After the sealing is completed, the shield machine reception is completed and the shield machine removal work will begin.

[0135] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An underwater portal sealing method for a shield machine portal entry, characterized in that: The method comprises the following steps: Step 1: When the shield machine enters the hole, if serious leakage occurs, immediately backfill water into the shield machine receiving well, and the water level of the backfill water is consistent with the water level of the confined water, so as to balance the internal and external water pressure balance of the shield machine receiving well; Step 2: Grouting the ground in the tunnel construction area, wherein the grouting comprises shallow layer filling grouting of the top of the tunnel and deep layer micro-disturbance grouting of the two sides of the tunnel; Step 3: Reinforcing the inside of the tunnel, wherein the inside reinforcement of the tunnel comprises polyurethane pressure injection, support system installation, shield machine shell grouting and tunnel bottom micro-disturbance grouting; Step 4: Before the shield machine is pushed again, a steel ring (9) is installed on the large misaligned tunnel segment (41) to reinforce it; Step 5: Remove the steel pipe support system in the tunnel (4) and carry out the shield machine pushing construction again; Step 6: After the shield machine is pushed into place again, underwater hole sealing welding is carried out; Step 7: Water is pumped out of the shield machine receiving well and hole sealing reinforcement welding is carried out; Step 8: After the hole sealing reinforcement is completed, single liquid slurry is injected into the hole, and cement mortar is backfilled; Step 9: After the grouting slurry in step 8 is initially set, shield cutting operation is carried out, and after the cutting is completed, the exposed grease pipe and synchronous grouting pipe of the shield tail are welded and sealed with iron plates, and after the sealing is completed, the shield machine receiving is completed.

2. The underwater portal sealing method for a tunneling machine to enter a portal according to claim 1, characterized in that: The construction method of the shallow layer filling grouting of the top of the tunnel is as follows: In the area of the shield machine receiving well corresponding to the ground surface where the roadbed is greatly subsided, shallow layer single liquid slurry grouting is carried out, and a plurality of second grouting holes (2) for cement slurry filling grouting are punched on the outside of the concrete road surface of the shield machine receiving well, the punching depth of the second grouting holes (2) is consistent with the thickness of the roadbed, and cement slurry filling grouting is carried out in the second grouting holes (2) to fill the gap between the roadbed and the original soil.

3. The underwater portal sealing method for a tunneling machine to enter a portal according to claim 1, characterized in that: The construction method of the deep layer micro-disturbance grouting of the two sides of the tunnel is as follows: Deep layer micro-disturbance grouting is carried out on the upper sides of the two sides of the tunnel (4) near the leakage point, the third grouting holes (3) of the deep layer micro-disturbance grouting are arranged on the left and right sides of the tunnel edge line, and the third grouting holes (3) on the left and right sides are arranged in parallel and symmetrically, and the grouting depth of the deep layer micro-disturbance grouting is from below the structure bottom surface of the tunnel (4) to above the structure bottom surface of the tunnel (4).

4. The underwater portal sealing method for a tunneling machine to enter a portal according to claim 1, characterized in that: The construction method of the polyurethane pressure injection is as follows: polyurethane is injected into the tunnel bottom of the shield machine receiving section to seal the water leakage channels of the hole and the tunnel segment.

5. The underwater portal sealing method for a tunneling machine to enter a portal according to claim 1, characterized in that: The support system installation comprises the following steps: Step S1: Install a support steel pipe in the shield machine receiving section, wherein the support steel pipe comprises one horizontal support (5) and two vertical supports (6); the two vertical supports (6) are symmetrically arranged about the longitudinal center axis of the tunnel (4), the horizontal support (5) is vertically connected with the two vertical supports (6) and is located below the horizontal center axis of the tunnel (4); an inclined support is additionally installed at the large misaligned tunnel segment (41); Step S2: In the shield machine receiving section, tunnel segment connecting plates are installed between adjacent two rings of tunnel segments (41), and the tunnel segment connecting plates are welded and connected into an integrated structure through tension strips. Step S3: installing several tunnel stay bars (7) outside the tunnel segment (41), the tunnel stay bars (7) are fixedly connected with the tunnel segment (41) through the stay bar bottom plate (71) and the anchoring (72), and the auxiliary stay bar (8) is arranged between the large-misaligned tunnel segment (41) and the tunnel stay bar (7).

6. The underwater portal sealing method for a tunneling machine to enter a portal according to claim 1, characterized in that: The shield shell grouting construction method is: Two shell grouting holes are arranged on the tunnel segment (41), including a plurality of A-ring shell grouting holes (43) arranged on both sides of the A-ring at the front shield of the shield and a plurality of articulated shield tail grouting holes (44) arranged at the tail of the shield and along the ring direction, and each A-ring shell grouting hole (43) and articulated shield tail grouting hole is provided with a grouting ball valve; before the shield is pushed again, except for the articulated shield tail grouting hole at the top end of the tunnel segment (41), the A-ring shell grouting hole (43) and the remaining articulated shield tail grouting hole (44) are used for hoop pressure grouting, and the grouting ball valve is kept unblocked after the pressure grouting, so that the secondary hoop pressure grouting can be carried out during the shield pushing stage.

7. The underwater portal sealing method for a tunneling machine to enter a portal according to claim 1, characterized in that: The installation method of the riding seam steel ring (9) is: The bracket (42) is installed on the misaligned tunnel segment (41), the bracket (42) is leveled with the tunnel segment (41) of the next ring of the misaligned tunnel segment (41), so that the riding seam steel ring (9) can be connected in the ring direction between the bracket (42) and the tunnel segment (41) of the next ring of the misaligned tunnel segment (41), and the riding seam steel ring (9) is connected in the ring direction between the misaligned tunnel segment (41) and the tunnel segment (41) of the previous ring of the misaligned tunnel segment (41).

8. The underwater portal sealing method for a tunneling machine to enter a portal according to claim 1, characterized in that: The step 6 includes the following sub-steps: Step 6.1: before the shield receives, the arc-shaped steel ring (10) is welded at the bottom of the shield shell (12); Step 6.2: the arc-shaped steel plate (11) is welded on the shield shell (12) in the order of from bottom to top and from left to right, and a plurality of arc-shaped steel plates (11) at the bottom of the shield shell (12) are fixedly welded with the arc-shaped steel ring (10); Step 6.3: a plurality of triangular fine plates are welded on each arc-shaped steel plate (11).

9. The underwater portal sealing method for a tunneling machine to enter a portal according to claim 1, characterized in that: The step 7 includes the following sub-steps: Step 7.1: water pumping test, if all the leakage channels are reliably blocked, step 7.2 is executed, and if the leakage channels are not reliably blocked, the tunnel (4) is subjected to hoop grouting; Step 7.2: the sealing plate is welded from top to bottom to block and reinforce the hole door.

10. The underwater portal sealing method for a tunneling machine to enter a portal according to claim 9, characterized in that: The step 7.1 includes the following sub-steps: Step 7.1.1: water is pumped in the shield receiving well, so that the water level of the shield receiving well is lowered by 1m than the original soil water level, the water level change in the well is observed after stopping pumping for 2-3 hours, and the water level change curve is drawn; if the water level curve has no rising phenomenon, that is, the leakage channel above the water surface is reliably blocked, step 7.1.2 is executed; if the water level has obvious change, the leakage channel above the water surface is not reliably blocked, then the water level is immediately backfilled to the original water level before pumping, and the hoop grouting is carried out in the tunnel (4); Step 7.1.2: The water level in the shield machine receiving well is lowered by 1 m again, and the water level in the well is observed for 2-3 hours. If the water level curve remains stable, the leakage channel above the water surface is reliably sealed, and step 7.1.3 is performed. If the water level changes significantly, the leakage channel above the water surface is not reliably sealed, and the water level is immediately restored to the original water level before pumping, and the ring hoop grouting work in the tunnel (4) is performed; Step 7.1.3: The water level in the shield machine receiving well is lowered by 1 m again, and the water level in the well is observed for 2-3 hours. If the water level is stable, the leakage channel is reliably sealed, and if the water level changes significantly, the leakage channel above the water surface is not reliably sealed, and the water level is immediately restored to the original water level before pumping, and the ring hoop grouting work in the tunnel (4) is performed; Step 7.1.4: Repeat step 7.1.3 until the water level is stable and the pumping test is qualified; The step 7.2 includes the following steps: Step 7.2.1: Pump the water in the shield machine receiving well to below the first sealing plate (15) and meet the welding construction space requirements of the first sealing plate (15), weld the first sealing plate (15), and seal and reinforce the portal; Step 7.2.2: Pump the water again to below the second sealing plate (15) and the third sealing plate (15), and meet the welding construction space requirements of the second sealing plate (15) and the third sealing plate (15), weld the second sealing plate (15) and the third sealing plate (15), and seal and reinforce the portal; Step 7.2.3: Repeat step 7.2.2, pumping water while welding the sealing plate (15), until all the sealing plates (15) are welded, and the portal is sealed and reinforced; Step 7.2.4: Use double quick cement to seal the gap between the shield machine shell (12) and the sealing plate (15), and at the same time, reserve a grouting hole at the arc-shaped steel plate (11) and configure a grouting ball valve.

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