An air pressure type retreat method for an underground shield machine

Abstract

The present invention relates to a pneumatic backward method for an underground shield machine, which is applied in the technical field of tunnel construction to solve the technical problem of difficult maintenance of the cutter head of the underground shield machine. The pre-stop preparation work includes the following steps: controlling the excavation diameter to be greater than or equal to the cutter head diameter; injecting high-viscosity bentonite outside the segments of 2-5 rings close to the shield tail; selecting a stable stratum for stopping the machine. The post-stop preparation work includes the following steps: making a water stop ring outside the segments of 6-8 rings close to the shield tail; sealing between the outer shell of the shield machine and the soil layer with high-viscosity bentonite; closing all the hatches leading to the soil chamber inside the shield body and sealing the screw conveyor with polyurethane; conducting a pressure test to detect whether the soil chamber leaks air; injecting high pressure into the soil chamber of the shield machine through the pressure maintaining system of the shield machine to make the shield machine move backward. The present invention has the effects of high efficiency and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of the underground retreat of a shield machine, and more specifically, it relates to a pneumatic retreat method for an underground shield machine. Background Art

[0002] During the process of the shield machine tunneling underground, its relationship with the stratum is very close. The characteristics of the stratum have a great impact on the construction speed of the tunnel, and also have a great impact on the performance and service life of the shield machine. When selecting and designing the shield machine, it will be designed according to the geological exploration report to ensure that the shield machine can excavate the stratum with the greatest hardness.

[0003] Since the geological exploration is carried out at intervals of 100 m, especially in hilly and mountainous areas such as Fujian Province and Sichuan Province, as well as in the case of underground remaining buildings, the error of the geological exploration is very large, resulting in damage to the cutter head and increased normal wear of the cutters. It is often necessary to manually excavate the front heading face for operations such as modifying the cutter head and replacing the cutters.

[0004] The above-mentioned excavation method requires manual operation. When the stratum is very hard, the difficulty of manual excavation is extremely huge, the material cost and the construction period cost are very high, and the danger is very high. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a pneumatic retreat method for an underground shield machine, and its advantage is to reduce the construction cost and save the construction period.

[0006] The above technical purpose of the present invention is achieved through the following technical solutions: A pneumatic retreat method for an underground shield machine includes the following steps:

[0007] 10 Preparation measures before shutdown;

[0008] The preparation work before shutdown includes the following steps:

[0009] Control the excavation diameter to be greater than or equal to the cutter head diameter;

[0010] Inject high-viscosity bentonite outside the 2-5 rings of segments close to the shield tail;

[0011] 20 Select a stable stratum for shutdown;

[0012] 30 Preparation measures after shutdown;

[0013] The preparation work after shutdown includes the following steps:

[0014] Make a water stop ring outside the 6-8 rings of segments close to the shield tail;

[0015] Seal between the shield machine shell and the soil layer with high-viscosity bentonite;

[0016] Close all the hatches leading to the hopper inside the shield body and seal the auger with polyurethane;

[0017] Conduct a pressure test to check if the hopper is airtight;

[0018] Inject high pressure into the hopper of the shield machine through the shield machine pressure maintaining system to make the shield machine retreat.

[0019] Further set: The stable formation can be a single formation or formations with the same mechanical properties.

[0020] Further set: In the preparatory measures before shutdown, the outer sides of the 2-3 rings of segments near the shield tail are polished smooth and evenly coated with 10-15 liters of butter.

[0021] Further set: Before the shield machine stops in step 20, adjust the telescopic amount of the articulated cylinders so that the overall shield body is in a cylindrical shape.

[0022] Further set: In the preparatory measures after shutdown, a total of 60-80 cubic meters of bentonite is injected into the outer shell of the shield machine. The bentonite is evenly injected from the bottom upwards to both sides, so that the outer side of the shield machine shell is evenly covered with bentonite.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Since the formation is specifically hard granite with a hardness of 80 MPa, it is difficult, costly, and time-consuming to manually excavate a 1-meter maintenance space. The backward movement method of the pneumatic shield machine, although it has high requirements for the formation and is difficult to select the shutdown position, is simple in overall operation, fast in efficiency, and low in construction difficulty, and can save a large amount of construction time;

[0025] 2. High safety. Compared with the operation space formed by manual excavation, the operation space formed by backward movement with pneumatic pressure reduces the time of working in a confined space, and the overall safety is more reliable;

[0026] 3. Environmental protection. Compared with manual excavation, the backward movement method with pneumatic pressure has less noise and does not generate particles such as dust and flying chips, effectively protecting the environment inside the tunnel;

[0027] 4. Short construction period. After the shield machine stops, inflation and backward movement can be carried out after three days of preparation, greatly shortening the construction period;

[0028] 5. Low cost. The equipment, labor, steel, and transportation required are very small, reducing costs;

[0029] 6. After the shield machine retreats, the face is intact, avoiding problems such as tool deformation and uneven wear caused by uneven tool forces. Description of the Drawings

[0030] Figure 1 is a schematic diagram of the state of the shield machine before shutdown in this embodiment;

[0031] Figure 2 is a schematic diagram of the state of the shield machine after shutdown in this embodiment;

[0032] Figure 3a is Figure 2 the enlarged view of part A in

[0033] Figure 3b is Figure 2 the enlarged view of part B in

[0034] Figure 4 is a schematic diagram of the state of the shield machine after the preparation work for backward movement is completed in this embodiment;

[0035] Figure 5 is a structural schematic diagram of the shield machine after the backward movement is completed in this embodiment.

[0036] In the figure: 1, segment; 2, shield tail; 3, screw conveyor; 4, shield body; 5, soil chamber; 6, propulsion cylinder; 7, articulated cylinder; 8, cutter head; 9, backing plate. Specific implementation mode

[0037] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0038] Embodiment: Refer to Figures 1-5 , a pneumatic backward movement method for an underground shield machine, comprising the following steps:

[0039] 10 The preparation measures before shutdown include the following steps:

[0040] Control the excavation diameter to be greater than or equal to the diameter of the cutter head 8, and the over-excavation value can be controlled within 5 mm;

[0041] Inject high-viscosity bentonite outside the 2-5 ring segments 1 near the shield tail 2; the 1-2 ring segments 1 within the range of the shield tail brush do not need to be injected with bentonite. Cement slurry was originally injected outside all segments 1. After the cement slurry solidifies, it is difficult to compress. Replace the cement slurry with bentonite. Bentonite has certain fluidity and sealing performance. After the shield tail 2 moves backward, the bentonite can flow forward from the gap between the shield shell and the soil layer, so as to reduce the backward resistance of the shield tail 2;

[0042] Increase the injection amount of grease for the shield tail 2 to prevent serious damage and air leakage of the shield tail brush during the backward movement;

[0043] For a shield machine equipped with a hinged system, it is necessary to adjust the telescopic amounts of all the hinged cylinders 7 to be the same, so that the front and rear of the shield body 4 are coaxial and cylindrical, reducing the resistance during the reverse movement of the shield machine;

[0044] A backing plate 9 is provided between the last ring of segment 1 near the shield tail 2 and the shield tail 2 to prevent the last ring of segment 1 from being suspended. The backing plate 9 can be made of profiles with corresponding dimensions, steel plates with corresponding thicknesses, etc. according to the gap between the segment 1 and the shield tail 2;

[0045] The outer sides of the last 2 - 3 rings of segments 1 near the shield tail 2 are polished and lubricating oil is applied. A total of 10 liters of lubricating oil is used, and the outer sides of the segments 1 are evenly coated;

[0046] The retraction stroke of the propulsion cylinder 6 is greater than the reverse stroke of the shield machine.

[0047] Select a stable formation for shutdown;

[0048] The stable formation is specifically a single formation, such as a granite formation, a soft soil formation, or a moderately weathered rock formation. The mechanical properties of such formations are uniform and stable. For soft soil formations, anchor bolts can be embedded in the formation in advance and concrete can be injected for reinforcement before the reverse movement is implemented. Specifically, in this embodiment, the granite formation is taken as an example, with a hardness of more than 80 MPa. The entire shield machine is placed in the stable formation, and the length of the stable formation covers the sum of the length of the shield machine main body and the reverse space length of the shield machine. During shutdown, the stability of the formation is judged by opening the chamber and observing the face to ensure that the face will not collapse.

[0049] Preparatory measures after shutdown;

[0050] The preparatory work after shutdown includes the following steps:

[0051] A water stop ring is made on the outer sides of the 6 - 8 rings of segments 1 near the shield tail 2; if there is no groundwater, the water stop ring can be omitted.

[0052] The space between the shield machine shell and the soil layer is sealed with high - viscosity bentonite; the high - viscosity bentonite has fluidity and sealing properties. The bentonite is gradually injected evenly from the bottom to both sides upwards, so that the bentonite evenly covers the outer side of the shield machine shell. A total of 60 - 80 cubic meters of bentonite needs to be injected. The bentonite is injected through the grouting holes leading from the inside of the middle shield to the outside, so that the bentonite fills the gap between the shield machine shell and the formation, playing a sealing role. At the same time, the bentonite also has a lubricating effect, reducing the friction between the shield body and the formation;

[0053] All hatches of the soil bin 5 are closed inside the shield body 4, and the screw machine 3 is sealed with polyurethane; after the soil bin 5 of the shield machine is emptied, the screw machine 3 continues to rotate, half of the soil inside the screw machine 3 is discharged, and then polyurethane is injected, and then the screw machine 3 is reversed to allow the polyurethane to enter the middle position of the screw machine 3. The polyurethane is specifically hydrophilic polyurethane. The outer diameter of the screw machine 3 is 80cm-90cm, and a total of 20 barrels / 10L of polyurethane are required;

[0054] Test the pressure to ensure that the soil bin 5 is in a sealed space. The pressure in the soil bin 5 reaches 0.1 MPa and there is no pressure relief within 5 minutes.

[0055] 40 Injecting high pressure into the soil bin 5 of the shield machine through the shield machine pressure maintenance system to make the shield machine retreat;

[0056] Taking a shield machine with an excavation diameter of 8 meters as an example, the weight of its shield body 4 is between 800 and 1000 tons. At this time, the shield machine as a whole is regarded as a piston rod, the stratum is regarded as a cylinder, and the formed tunnel is used as a cavity for the shield body 4 to slide. High-pressure gas is injected into the front of the cutter head 8. The effective area of ​​the high-pressure gas can be approximately regarded as the circular area where the middle shield diameter is located. At this time, through the pressure calculation formula P=F / S, the pressure of the soil bin 5 is calculated to be 0.3 MPa, and a thrust of nearly 1400 tons can be obtained. The stratum is granite with a hardness of 80 MPa, which meets the implementation conditions. At the same time, the pressure of the shield machine's own pressure maintaining system is above 1 MPa, and the pressure that the shield machine equipment itself can generate meets the shield machine's retreat requirements.

[0057] Using the shield machine's own pressure-maintaining system, air is inflated into the cutterhead 8 of the shield machine. When the air pressure reaches a certain value, the shield machine begins to slowly retreat. During the retreat of the shield machine, the piston rod of the thrust cylinder 6 is gradually retracted by 5-8 cm, and then the shield machine retreats again. The above process is repeated in sequence until the shield machine retreats 1 meter.

[0058] 50 The pipe segment 1 in the shield tail 2 is removed and the shield tail brush is replaced.

[0059] This implementation method is applicable to all shield machines within 9 meters.

[0060] The implementation principle of the above embodiment is: the shield machine is sealed from the middle shield position by injecting bentonite from the outside, the position of the shield machine connecting to the soil bin is closed, and the screw machine is sealed with polyurethane. High-pressure gas is injected into the soil bin to make the shield machine retreat.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An air pressure type backward movement method for an underground shield machine, characterized in that: It includes the following steps: 10 Preparation measures before shutdown; The preparation work before shutdown includes the following steps: Control the excavation diameter to be greater than or equal to the diameter of the cutter head (8); Inject high-viscosity bentonite outside the segments (1) of the 2-5 rings close to the shield tail (2); 20 Select a stable stratum for shutdown; 30 Preparation measures after shutdown; The preparation work after shutdown includes the following steps: Make a water stop ring outside the segments (1) of the 6-8 rings close to the shield tail (2); Seal between the outer shell of the shield machine and the soil layer with high-viscosity bentonite; Inside the shield body (4), close the hatch doors of all soil bins (5), and seal the screw conveyor (3) with polyurethane; Conduct a pressure test to detect whether the soil bin (5) leaks air; 40 Inject high pressure into the soil bin (5) of the shield machine through the shield machine pressure maintenance system to make the shield machine retreat; In the preparation measures before shutdown, the outer sides of the segments (1) of the 2-3 rings close to the shield tail (2) are polished smoothly and evenly smeared with 10-15 liters of butter in total.

2. The pneumatic reverse method of the underground shield machine according to claim 1, characterized in that: The stable stratum is a single stratum or strata with the same mechanical properties.

3. The pneumatic reverse method of the underground shield machine according to claim 1, characterized in that: Before the shield machine shuts down in step 20, adjust the telescopic amount of the articulated cylinder (7) so that the shield body (4) is in a cylindrical shape as a whole.

4. The pneumatic retraction method of the underground shield machine according to claim 1, characterized in that: In the preparation measures after shutdown, a total of 60-80 cubic meters of bentonite is injected into the outer shell of the shield machine. The bentonite is evenly injected from the bottom to both sides and gradually upwards, so that the bentonite evenly covers the outside of the shield machine shell.

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