Construction method for reinforcing stratum to assist in warehouse entering operation after shield shutdown in subsidence area

Abstract

The invention discloses a construction method for reinforcing stratum auxiliary warehouse entering operation after shield shutdown in a subsidence area, and relates to the technical field of reinforcement. The construction method specifically comprises the steps that 1, the stratum reinforcing range of the subsidence area is determined; 2, designing grouting parameters of the subsidence area; 3, grouting reinforcement is conducted on the ground of the subsidence area; 4, grouting and water stopping are conducted in the hole; 5, a mud film is built on the tunnel face; step 6, reinforcement quality detection; and 7, under-pressure warehouse entering operation is carried out. Grouting work is carried out on a reinforced area from the ground, so that gaps between cavities and particles generated by collapse are directly filled, the risk of secondary collapse can be remarkably reduced, a compact impervious layer can be formed above a shield body firstly through ground reinforcement, the stratum can bear higher seepage pressure, and the stratum can bear higher seepage pressure. And the slurry permeation distance and compactness are better, and a better reinforcing effect can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of reinforcement technology, and in particular to a construction method for auxiliary entry operation of reinforced strata after a shield machine is shut down in a collapsed area. Background Art

[0002] When the shield tunnel is in the upper sand layer and the lower fully weathered muddy siltstone stratum, and the tunnel face collapses during the preparation for entering the warehouse after the machine is shut down near the structure, the conventional in-tunnel reinforcement and water-stopping and air pressure entry methods cannot guarantee that the tunnel face will not collapse again, and may also cause the deformation of the structure to exceed the limit.

[0003] For example, the announcement number CN108425680A, published on August 21, 2018, disclosed a method for treating ground collapse caused by shield tunneling, including the following steps: (1) reinforcing and dewatering the ground around the shield machine; (2) cleaning the debris in the tunnel and repairing the equipment; (3) freeing the shield machine and taking measures after the escape; and (4) constructing measures for the remaining section under the shield machine. A shield tunneling ground collapse re-pushing support structure is also disclosed, including rows of interlocking piles arranged in front of the shield machine cutterhead, on both sides of the shield body, and at the shield tail segment. The gap between the bottom of the interlocking piles and the top of the shield tail tunnel is filled with a chemical slurry for sealing and stopping water. A number of dewatering wells are opened between the shield machine cutterhead and both sides of the shield body and the interlocking piles. The above-disclosed reinforcement method cannot achieve stable reinforcement of the collapsed area of ​​the upper sand layer and the lower fully weathered muddy siltstone stratum. Summary of the Invention

[0004] The present invention aims to provide a method for enhancing the reinforcement of subsidence areas after shield tunneling. Grouting is performed directly into the subsidence area from the ground, filling the voids and gaps between particles caused by the collapse. This significantly reduces the risk of secondary collapse and provides enhanced reinforcement in the subsidence area.

[0005] To achieve the above-mentioned purpose, the present invention solves the technical problem by adopting a technical solution: a construction method for auxiliary entry operation of reinforced strata after the shield machine is shut down in a subsidence area, the specific steps of which include:

[0006] Step 1: Determine the scope of stratum reinforcement in the collapsed area;

[0007] Step 2: Design grouting parameters for the subsidence area;

[0008] Step 3: Grouting reinforcement of the ground in the collapsed area;

[0009] Step 4: Grouting to stop water in the hole;

[0010] Step 5: Establish mud film on the tunnel face;

[0011] Step 6: Reinforcement quality inspection;

[0012] Step 7: Pressurized storage operation.

[0013] The specific reinforcement range of the collapsed area in step 1 is as follows: the horizontal reinforcement range is from 3m in front of the shield machine cutter head to 3m behind the incision ring, and the shield body expands 3m on both sides; the vertical reinforcement range is from the ground to 1m of fully weathered muddy siltstone, and chemical slurry is used to reinforce the upper part of the shield body within 0.5 to 1.5m to form a protective layer around the shield body, and conventional double-liquid slurry is used to reinforce the area from 1m above the shield body to the ground.

[0014] The grouting parameters in step 2 specifically include: grouting hole position setting, grouting slurry configuration and grouting control.

[0015] The grouting holes are arranged in a 1.5mx1.5m plum blossom pattern.

[0016] The grouting slurry specifically includes chemical slurry and double-liquid slurry, and the chemical slurry and double-liquid slurry specifically include liquid A, liquid B and liquid C;

[0017] Wherein, liquid A includes water glass and water, and the ratio of liquid A is water glass: water = 1:03;

[0018] Liquid B includes phosphoric acid and water, and the ratio of liquid B is phosphoric acid: water = 1:18;

[0019] Liquid C includes cement and water, and the ratio of liquid C is cement: water = 1:1.5;

[0020] The chemical slurry is prepared using AB liquid, A liquid: B liquid = 1:1;

[0021] The double-liquid slurry is prepared using AC liquid, A liquid: B liquid = 1:1.

[0022] The grouting control specifically includes pressure control and settlement control. The grouting pressure ensures that the ground surface is not penetrated and does not exceed the sealing pressure of the shield tail of the shield machine. The pressure increase during a single grouting does not exceed 0.2MPa. Settlement control ensures that the deformation of ground structures does not exceed the limit during grouting.

[0023] The specific steps of step 3, ground grouting, include: using a drilling and grouting machine to reinforce the ground; measuring and setting out the ground, aligning the hole mark, and then pressing down the drill pipe to begin drilling; after reaching the designed depth, connecting liquid A and liquid B for chemical grouting reinforcement; when the grouting pressure reaches the designed pressure, lifting the drill pipe upward and continuing grouting to the designed pressure; grouting is performed in a 0.5m interval at an upward cycle; after reaching the designed elevation for chemical grouting reinforcement, the liquid B pipe is removed, the pipe is cleaned, and the liquid C pipe is connected to prepare for cement and water glass dual-liquid slurry injection; grouting is also performed in a 0.5m interval at an upward cycle. After the single hole injection is completed, the grouting hole is sealed with quick-drying, slightly expansive cement, and the drilling rig is moved to prepare for the next hole.

[0024] The grouting and water-stopping of step 4 specifically includes: after the ground grouting is completed, a water-stop ring is simultaneously constructed in the hole, polyurethane is injected on the shield body to fill the gap outside the shield body, and double-liquid slurry is injected behind the shield tail to stabilize the rear pipe segment.

[0025] The specific steps of establishing the mud film on the tunnel face in step 5 include: after the grouting reinforcement is completed, first injecting bentonite mud into the soil bin to replace the debris in the bin, discharging the residual debris in the bin through mud circulation, and gradually replacing the debris in the bin with high-quality, high-viscosity mud. After static pressure for 24 hours, lowering the liquid level to the working height to test the airtightness of the mud film on the tunnel face.

[0026] The reinforcement quality inspection in step 6 includes two items:

[0027] 1) Permeability test of reinforcement body: After ground grouting (i.e. after step 3 is completed), drill a hole in the ground to conduct a ground permeability test. The ground permeability is required to be no more than 1*10-6cm / s. If it does not meet the requirements, additional grouting reinforcement should be carried out. After the test, additional grouting reinforcement should be carried out on the exploration hole.

[0028] 2) Tunnel face airtightness test: After the mud film is established on the tunnel face (i.e., after step 5 is completed), the chamber is lowered to replace the mud in the chamber with high-pressure gas. The Samson pressure-maintaining system is set at the chamber entry pressure. If the excavation chamber pressure fluctuates less than 5 kPa within 2 hours, the pressure-maintaining test is qualified. If it fails, further formation reinforcement is required.

[0029] The beneficial effects of the present invention are:

[0030] By grouting the reinforced area from the ground, the voids and gaps between particles generated by the collapse can be directly filled, which can significantly reduce the risk of secondary collapse. In addition, through ground reinforcement, a dense impermeable layer can be formed above the shield, allowing the stratum to withstand higher penetration pressure, and the mud penetration distance and density are also improved, which can achieve better reinforcement effect.

[0031] Reinforcement work is carried out by replacing traditional cement with chemical slurry. Chemical slurry has the advantage of fast solidification speed, and is more efficient in reinforcing strata in water-rich sand layers. Chemical slurry also has the advantage of low strength after solidification. Reinforcement after the shield machine is shut down does not require worrying about the shield machine getting stuck and being unable to push again. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flowchart of the method of the present invention.

[0033] Figure 2 This is the reinforcement plan layout.

[0034] Figure 3 This is the reinforcement section layout diagram.

[0035] Figure 4 It is a specific construction flow chart. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0038] like Figure 1 As shown in the figure, the construction method for auxiliary entry operation of reinforced stratum after the shield machine is stopped in the collapse area includes the following specific steps:

[0039] Step 1: Determine the scope of stratum reinforcement in the collapsed area;

[0040] Step 2: Design grouting parameters for the subsidence area;

[0041] Step 3: Grouting reinforcement of the ground in the collapsed area;

[0042] Step 4: Grouting to stop water in the hole;

[0043] Step 5: Establish mud film on the tunnel face;

[0044] Step 6: Reinforcement quality inspection;

[0045] Step 7: Pressurized warehousing operation. After the on-site reinforcement quality inspection is passed, the warehousing operation is carried out according to the conventional pressurized warehousing process.

[0046] When reinforcing a collapsed area, the reinforcement range is determined based on the actual collapsed area, and then the grouting parameters are designed for the area that needs grouting based on the reinforcement range. By grouting the reinforced area from the ground, the voids caused by the collapse and the gaps between particles are directly filled, which can significantly reduce the risk of secondary collapse. In addition, through ground reinforcement, a dense impermeable layer can be formed above the shield first, so that the stratum can withstand higher seepage pressure, and the mud penetration distance and density are also better, which can achieve better reinforcement effect.

[0047] In one embodiment, the scope of reinforcement of the collapsed area in step 1 is specifically as follows: Figure 2 The plane reinforcement range is from 3m in front of the shield cutter head to 3m behind the cutter ring, and the shield body is expanded 3m on both sides; refer to Figure 3 The vertical reinforcement range is from the ground to 1m of fully weathered muddy siltstone. Chemical slurry is used to reinforce the upper part of the shield within 0.5 to 1.5m to form a protective layer around the shield. Conventional double-liquid slurry is used to reinforce the area from 1m above the shield to the ground.

[0048] By using conventional double-liquid slurry reinforcement above the shield, the strength of the reinforced upper part of the shield is ensured, which facilitates the subsequent establishment of a mud film on the tunnel face, thereby increasing the stability of the reinforced collapse area.

[0049] Specifically, the grouting parameters in step 2 include: grouting hole position setting, grouting slurry configuration and grouting control.

[0050] The specific hole positions of the grouting holes are arranged in a plum blossom pattern of 1.5mx1.5m, so as to ensure that the slurry enters the collapsed area evenly during grouting, thereby ensuring the stability of the reinforcement.

[0051] Grouting slurry chemical slurry and double liquid slurry, slurry chemical slurry and double liquid slurry specifically include A liquid, B liquid and C liquid;

[0052] Wherein, liquid A includes water glass and water, and the ratio of liquid A is water glass: water = 1:03;

[0053] Liquid B includes phosphoric acid and water, and the ratio of liquid B is phosphoric acid: water = 1:18;

[0054] Liquid C includes cement and water, and the ratio of liquid C is cement: water = 1:1.5;

[0055] Chemical slurry is prepared using AB liquid, A liquid: B liquid = 1:1

[0056] The double-liquid slurry is prepared using AC liquid, A liquid: B liquid = 1:1.

[0057] Chemical slurry solidification has the advantage of fast solidification speed, and is more efficient in reinforcing strata in water-rich sand layers. Chemical slurry also has the advantage of low strength after solidification. When reinforcing after the shield machine is shut down, there is no need to worry about the shield machine getting stuck and unable to be restored. This not only ensures the stable reinforcement of the collapsed area, but also facilitates the subsequent convenient re-pushing of the shield body, preventing the shield body from getting stuck in the soil bin and causing the cutter head to get stuck.

[0058] Grouting control specifically includes pressure control and settlement control. The grouting pressure ensures that the ground surface is not penetrated and does not exceed the sealing pressure of the shield tail of the shield machine. The pressure increase during a single grouting does not exceed 0.2MPa. Settlement control ensures that the deformation of ground structures does not exceed the limit during grouting.

[0059] This ensures that the pressure of the slurry during grouting does not cause damage to the shield machine and ground buildings, thereby enabling the slurry to stably enter the collapsed area for reinforcement work and ensuring that the subsequent shield machine can carry out excavation work.

[0060] Step 3: Ground grouting: The specific steps include: using a drilling and grouting machine for ground reinforcement, measuring and aligning the hole location markers on the ground, and then pressing down the drill pipe to begin drilling. After reaching the designed depth, connect liquid A and liquid B for chemical grouting reinforcement. When the grouting pressure reaches the designed pressure, lift the drill pipe upward and continue grouting to the designed pressure. Grouting is performed in a 0.5m interval. After reaching the designed elevation for chemical grouting reinforcement, the liquid B pipe is removed, the pipe is cleaned, and the liquid C pipe is connected to prepare for cement and water glass dual-liquid grouting. Grouting is also performed in a 0.5m interval. After the single hole is grouting is completed, the grouting hole is sealed with quick-drying, slightly expansive cement, and the drill rig is moved to prepare for the next hole.

[0061] Step 4, grouting and water-stopping, involves constructing a water-stop ring inside the tunnel after ground grouting is complete. Polyurethane is injected into the shield to fill the gap outside the shield, and dual-liquid grout is injected behind the shield tail to stabilize the rear segment. Before use, the water-stop ring must be quality-tested to ensure stable operation.

[0062] Step 5: Establishing a mud film on the tunnel face. The specific steps include: After the grouting reinforcement is completed, first inject bentonite mud into the soil bin to replace the debris in the bin, discharge the residual debris in the bin through mud circulation, and gradually replace the debris in the bin with high-quality, high-viscosity mud. After static pressure for 24 hours, lower the liquid level to the working height to test the airtightness of the mud film on the tunnel face.

[0063] The reinforcement quality inspection in step 6 includes two items:

[0064] 1) Permeability test of reinforcement body: After ground grouting (i.e. after step 3 is completed), drill a hole in the ground to conduct a ground permeability test. The ground permeability is required to be no more than 1*10-6cm / s. If it does not meet the requirements, additional grouting reinforcement should be carried out. After the test, additional grouting reinforcement should be carried out on the exploration hole.

[0065] 2) Tunnel face airtightness test: After the mud film is established on the tunnel face (i.e., after step 5 is completed), the chamber is lowered to replace the mud in the chamber with high-pressure gas. The Samson pressure-maintaining system is set at the chamber entry pressure. If the excavation chamber pressure fluctuates less than 5 kPa within 2 hours, the pressure-maintaining test is qualified. If it fails, further formation reinforcement is required.

[0066] Specific testing process reference Figure 4After the water stop ring quality inspection is qualified, first prepare the bentonite slurry, the soil bin bentonite slurry replaces the slag, circulates to establish a mud film, and the air system circulates and pressurizes, thereby performing air-slurry replacement, and the mud level is controlled at one-half of the soil bin, and then the soil bin air tightness test is carried out. After inspection, the air tightness does not meet the requirements, and the bentonite slurry is re-prepared, the soil bin bentonite slurry replaces the slag, circulates to establish a mud film, and air circulates and pressurizes, thereby performing air-slurry replacement, and the mud level is controlled at one-half of the soil bin, until the soil bin air tightness test is qualified. After the soil bin air tightness test is qualified, the man bin air tightness test is carried out. The man bin air tightness test result does not meet the requirements, and the man bin is inspected. After the man bin air tightness is qualified, the pressure is stable, and the man bin gas test is normal. At this time, the pressure is entered into the bin to check and change the tool. After the tool change is completed, the personnel leave the bin, close the hatch, and resume construction.

[0067] Before the air system is circulated and pressurized, the air compressor and mud circulation system need to be debugged, and the backup power supply and emergency supplies must be in place.

[0068] In summary, the reinforcement method of the present application has the following beneficial effects when used:

[0069] (1) Conventional cement slurry is difficult to solidify in water-rich sand layers, resulting in poor reinforcement quality. The chemical slurry used in the present invention has the advantage of fast solidification speed and higher reinforcement efficiency in water-rich sand layers;

[0070] (2) Conventional cement slurry has a relatively high strength after solidification. After the shield machine is shut down, in-situ grouting reinforcement can easily wrap around the shield body, making it difficult to re-push. If it enters the soil bin, it may even get the cutterhead stuck. The chemical slurry used in the present invention has the advantage of low strength after solidification. After the shield machine is shut down, reinforcement does not need to worry about the shield machine getting stuck and being unable to re-push.

[0071] (3) The operation of entering the silo in the water-rich sand layer generally adopts the technology of air-tight mud film and shield mud. However, these conventional technologies all form a dense airtight layer on the face of the tunnel. By injecting high-pressure gas into the silo, the air pressure balances the external water and soil pressure through the airtight layer. However, this airtight layer is only resistant to compression but not tension. In the sand layer that has collapsed, the face of the tunnel may collapse again as the collapse arch moves upward. The present invention uses grouting reinforcement on the ground to directly fill the voids generated by the collapse and the gaps between the particles, which can significantly reduce the risk of secondary collapse.

[0072] (4) Conventional mud penetration reinforcement methods increase the mud pressure to allow the mud to penetrate the strata around the face to form a dense penetration filling reinforcement area. However, due to the strong adsorption of mud, the mud penetration range is limited. In addition, since the stratum has already collapsed, excessive mud pressure in the chamber can easily lead to the stratum being penetrated and causing secondary collapse, endangering surrounding structures. Conventional processes have a general effect on the stability of the face. The present invention can first form a dense impermeable layer above the shield through ground reinforcement, so that the stratum can withstand higher penetration pressure, the mud penetration distance and density are also better, and a better reinforcement effect can be obtained.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A construction method for auxiliary entry operation of reinforced strata after shield machine shutdown in subsidence area, characterized in that: The specific steps include: Step 1: Determine the scope of stratum reinforcement in the collapsed area; Step 2: Design grouting parameters for the subsidence area; Step 3: Grouting reinforcement of the ground in the collapsed area; Step 4: Grouting to stop water in the hole; Step 5: Establish mud film on the tunnel face; Step 6: Reinforcement quality inspection; Step 7: Pressurized storage operation.

2. The method for auxiliary entry into the silo for reinforcement of the ground after the shield machine is shut down in a subsidence area according to claim 1, characterized in that: The specific reinforcement range of the collapsed area in step 1 is as follows: the horizontal reinforcement range is from 3m in front of the shield machine cutter head to 3m behind the incision ring, and the shield body expands 3m on both sides; the vertical reinforcement range is from the ground to 1m of fully weathered muddy siltstone, and chemical slurry is used to reinforce the upper part of the shield body within 0.5 to 1.5m to form a protective layer around the shield body, and conventional double-liquid slurry is used to reinforce the area from 1m above the shield body to the ground.

3. The method for auxiliary entry into the silo for reinforcement of the ground after the shield machine is shut down in a subsidence area according to claim 1, characterized in that: The grouting parameters in step 2 specifically include: grouting hole position setting, grouting slurry configuration and grouting control.

4. The method for auxiliary entry into the silo for reinforcement of the ground after the shield machine is shut down in a subsidence area according to claim 3 is characterized in that: The grouting holes are arranged in a 1.5mx1.5m plum blossom pattern.

5. The method for auxiliary entry into the warehouse for reinforcing the ground after the shield machine is shut down in a subsidence area according to claim 3 is characterized in that: The grouting slurry specifically includes chemical slurry and double-liquid slurry, and the chemical slurry and double-liquid slurry specifically include liquid A, liquid B and liquid C; Wherein, liquid A includes water glass and water, and the ratio of liquid A is water glass: water = 1:03; Liquid B includes phosphoric acid and water, and the ratio of liquid B is phosphoric acid: water = 1:18; Liquid C includes cement and water, and the ratio of liquid C is cement: water = 1:1.5; The chemical slurry is prepared using AB liquid, A liquid: B liquid = 1:1; The double-liquid slurry is prepared using AC liquid, A liquid: B liquid = 1:

1.

6. The method for auxiliary entry into the silo for reinforcement of the ground after the shield machine is shut down in a subsidence area according to claim 3, characterized in that: The grouting control specifically includes pressure control and settlement control. The grouting pressure ensures that the ground surface is not penetrated and does not exceed the sealing pressure of the shield tail of the shield machine. The pressure increase during a single grouting does not exceed 0.2MPa. Settlement control ensures that the deformation of ground structures does not exceed the limit during grouting.

7. A construction method for auxiliary entry into the stratum after shield tunneling in a subsidence area is stopped according to any one of claims 2 to 6, characterized in that: The specific steps of step 3, ground grouting, include: using a drilling and grouting machine to reinforce the ground; measuring and setting out the ground, aligning the hole mark, and then pressing down the drill pipe to begin drilling; after reaching the designed depth, connecting liquid A and liquid B for chemical grouting reinforcement; when the grouting pressure reaches the designed pressure, lifting the drill pipe upward and continuing grouting to the designed pressure; grouting is performed in a 0.5m interval at an upward cycle; after reaching the designed elevation for chemical grouting reinforcement, the liquid B pipe is removed, the pipe is cleaned, and the liquid C pipe is connected to prepare for cement and water glass dual-liquid slurry injection; grouting is also performed in a 0.5m interval at an upward cycle. After the single hole injection is completed, the grouting hole is sealed with quick-drying, slightly expansive cement, and the drilling rig is moved to prepare for the next hole.

8. The method for auxiliary entry into the silo for reinforcement of the ground after the shield machine is shut down in a subsidence area according to claim 7, characterized in that: The grouting and water-stopping of step 4 specifically includes: after the ground grouting is completed, a water-stop ring is simultaneously constructed in the hole, polyurethane is injected on the shield body to fill the gap outside the shield body, and double-liquid slurry is injected behind the shield tail to stabilize the rear pipe segment.

9. The method for auxiliary entry into the silo for reinforcement of the ground after the shield machine is shut down in a subsidence area according to claim 7, characterized in that: The specific steps of establishing the mud film on the tunnel face in step 5 include: after the grouting reinforcement is completed, first injecting bentonite mud into the soil bin to replace the debris in the bin, discharging the residual debris in the bin through mud circulation, and gradually replacing the debris in the bin with high-quality, high-viscosity mud. After static pressure for 24 hours, lowering the liquid level to the working height to test the airtightness of the mud film on the tunnel face.

10. A construction method for auxiliary entry into the stratum after shield machine shutdown in a subsidence area according to claim 9, characterized in that: The reinforcement quality inspection in step 6 includes two items: 1) Permeability test of reinforcement body: After ground grouting (i.e. after step 3 is completed), drill a hole in the ground to conduct a ground permeability test. The ground permeability is required to be no more than 1*10-6cm / s. If it does not meet the requirements, additional grouting reinforcement should be carried out. After the test, additional grouting reinforcement should be carried out on the exploration hole. 2) Tunnel face airtightness test: After the mud film is established on the tunnel face (i.e., after step 5 is completed), the chamber is lowered to replace the mud in the chamber with high-pressure gas. The Samson pressure-maintaining system is set at the chamber entry pressure. If the excavation chamber pressure fluctuates less than 5 kPa within 2 hours, the pressure-maintaining test is qualified. If it fails, further formation reinforcement is required.

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