Earth pressure balance shield model test device

Abstract

The application belongs to the technical field of shield construction and provides a soil pressure balance shield model test device, which comprises a rack, a sample mold, a moving bin and a test control system. The sample mold is fixed to one end of the inner cavity of the rack through a mold fixing frame. The moving bin is slidably connected to the other end of the inner cavity of the rack, and moves along a first direction. The moving bin comprises a soil bin and a foam configuration bin, which are independent cavities. The soil bin is rotationally connected with a cutting tool. The foam configuration bin is provided with a foam generator and a screw conveyor. The moving bin is provided with the test control system. The foam generator and the cutting tool are connected with each other and connected with the screw conveyor, so that the mechanical properties of the muck are monitored, the horizontal precise tunneling of the soil sample is performed, and the muck is discharged at the same time in the state of real-time foam modifier input.

Description

Technical Field

[0001] This invention belongs to the field of shield tunneling technology, and in particular relates to a test device for earth pressure balance shield tunneling models. Background Technology

[0002] Earth pressure balance (EPB) shield tunneling machines have become a promising type of tunnel boring machine. During excavation, the EPB shield achieves stability by balancing the pressure of the excavated soil within the earth chamber with that of the working face. Simultaneously, excavated soil is discharged via a screw conveyor within the earth chamber, and a soil discharge device installed at the discharge port continuously discharges soil while maintaining a balance between the amount of soil discharged and the amount of soil advanced. It is suitable for tunneling under most ground conditions, especially in water-saturated soft soil strata, clay, sand, and other soft soil foundations.

[0003] However, when EPB shield tunneling is excavating on the ground with poor soil consistency, the workability, permeability and plasticity of the excavated soil layer are not good, so it is impossible to achieve the best tunnel excavation. Therefore, obtaining the soil properties suitable for EPB shield construction is crucial to achieving the best tunnel excavation. In order to obtain soil in a low flow plastic state in EPB tunnel construction, soil improvement technology is usually used to improve the soil properties to improve the performance of EPB shield tunneling, including increasing the advance rate and reducing downtime.

[0004] With research into slag improvement technology, a foaming agent that is more practical than other slag improvement agents has been developed, and extensive research has been conducted on using foam as a slag improvement agent. However, EPB shield tunneling slag improvement technology is not yet fully mature, and the presence of air bubbles in the pores leads to the complexity of the behavior of soil-foam mixtures, so the actual behavior of soil under foam conditions has not yet been fully established.

[0005] Therefore, in order to further study the real behavior of soil under foam conditions, it is urgent to design an earth pressure balance shield tunneling model test device. Summary of the Invention

[0006] The purpose of this invention is to provide an earth pressure balance shield tunneling model test device to solve the above-mentioned problems. By connecting the foam generator, the cutting tool, and the screw conveyor, this invention enables simultaneous monitoring of the mechanical properties of the excavated soil, precise horizontal excavation of soil samples, and slag discharge while the foam modifier is introduced in real time. This can simulate the excavation situation of adding foam modifier in the actual earth pressure balance shield tunneling process.

[0007] To achieve the above objectives, the present invention provides the following solution, including:

[0008] frame;

[0009] The sample mold is fixed to one end of the inner cavity of the frame via a mold fixing frame.

[0010] The movable chamber is slidably connected to one end of the inner cavity of the frame away from the sample mold, and the movable chamber moves along a first direction; the movable chamber includes a soil chamber and a foam preparation chamber, which are independent cavities; the soil chamber is rotatably connected to a cutting component, the foam preparation chamber is equipped with a foam generator and a screw conveyor, and the movable chamber is equipped with a test control system.

[0011] Preferably, the foam generator is fixed to the inner wall of the foam preparation chamber. The foam generator has three inlets, two of which are connected to a foaming agent container and an additive container respectively through injection pipes, and the other inlet is connected to an air compressor pump through an air inlet pipe. The foam generator has one outlet, and the outlet of the foam generator is connected to two foam injection pipes through a tee, one of which is connected to the screw conveyor, and the other is connected to the cutting mechanism.

[0012] Preferably, the cutting mechanism includes a porous inner shaft and an outer cylinder. The outer cylinder is fixed to the inner wall of the soil chamber. The porous inner shaft passes through the outer cylinder, and several bearings are sleeved between the porous inner shaft and the outer cylinder. An electric motor is fixed to one side of the soil chamber. The output end of the electric motor passes through the end side wall of the outer cylinder and is fixed to the porous inner shaft. A tool assembly is fixed to the other end of the porous inner shaft. The inner cavity of the tool assembly is connected to the porous inner shaft. A first foam injection hole is opened on the outer cylinder, and the foam generator is connected to the first foam injection hole through a foam injection pipe.

[0013] Preferably, the tool assembly includes a tool disc, a feed hole is provided on one side of the tool disc, the multi-hole inner shaft is embedded in the feed hole, a plurality of cutting blades are detachably connected to the circumferential sidewall of the tool disc, the inner cavity of the cutting blades is connected to the inner cavity of the tool disc, a through hole is provided on the sidewall of the cutting blades facing the soil chamber, and cutting teeth are detachably connected to the ends of the plurality of cutting blades away from the tool disc.

[0014] Preferably, the screw conveyor includes a conveying cylinder, one end of which has a threaded outer wall, and the lower side wall of the foam preparation chamber has a mating thread. One end of the conveying cylinder is connected to the side wall of the foam preparation chamber via the thread and the mating thread, and the inner cavity of the conveying cylinder is connected to the soil chamber. The other end of the conveying cylinder passes through the foam preparation chamber and is fixedly connected to a fixing plate. A rotating motor is provided on the outer wall of the fixing plate, and the output end of the rotating motor passes through the fixing plate and is fixedly connected to an auger. A second foam injection hole is provided on the top surface of the conveying cylinder near the thread, and the foam generator is connected to the second foam injection hole via another foam injection pipe. A slag outlet is provided on the bottom surface of the conveying cylinder near the fixing plate.

[0015] Preferably, the foam generator further includes a fixed cylinder, which is fixedly connected to the foam configuration chamber. The three inlets and the outlet are all opened on the outer wall of the fixed cylinder. A reduction motor is fixedly connected to one end of the fixed cylinder. The output end of the reduction motor passes through the side wall of the fixed cylinder and is fixedly connected to a rotating cylinder. The inner cavity of the rotating cylinder is provided with several steel balls. The rotating cylinder and the fixed cylinder are rotatably connected by bearings.

[0016] Preferably, the moving mechanism includes a slide rail, which is fixedly connected to the inner cavity of the frame. The moving chamber is slidably connected to the slide rail via a shield support frame. A jack is fixedly connected to the side of the inner cavity of the frame away from the sample mold, and the output end of the jack is fixedly connected to the side wall of the moving chamber.

[0017] Preferably, the test control system includes two stirring motors respectively fixed above and below the side wall of the foam preparation chamber. The output ends of the two stirring motors pass through the side wall of the foam preparation chamber and are respectively fixed with stirring blades. The stirring blades are located inside the soil chamber. Sensors are also fixed on the stirring blades and the sensors are connected to the PC for signal transmission.

[0018] Preferably, the air pressure simulation system includes an air pump fixed to the inner wall of the foam configuration chamber, and the air pump is connected to the soil chamber via an air line.

[0019] Preferably, a sealing element is further provided between the porous inner shaft and the outer cylinder, and the side wall of the sealing element abuts against the tool assembly.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] This invention connects the foam generator to the cutting tool and to the screw conveyor, enabling simultaneous monitoring of the mechanical properties of the excavated soil, precise horizontal excavation of soil samples, and slag discharge while the foam modifier is introduced in real time. It can simulate the excavation situation of adding foam modifier during the actual earth pressure balance shield tunneling process. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of an earth pressure balance shield tunneling model test device according to the present invention;

[0024] Figure 2 This is a schematic diagram of the screw conveyor in this invention;

[0025] Figure 3 This is a schematic diagram of the tool assembly containing four cutting blades according to the present invention;

[0026] Figure 4 This is a schematic diagram of the tool assembly containing six cutting blades according to the present invention;

[0027] Figure 5 This is a schematic diagram of the cutting mechanism in this invention;

[0028] Figure 6 This is a schematic diagram of the foam generator in this invention;

[0029] Figure 7 for Figure 1 A magnified view of part A in the image;

[0030] The components include: 1. Frame; 2. Sample mold; 3. Moving chamber; 4. Soil chamber; 5. Air compressor pump; 6. Air line; 7. Air inlet pipe; 8. Foaming agent container; 9. Injection pipe; 10. Additive container; 11. Air pump; 12. Fixed cylinder; 13. Gear motor; 14. Sensor; 15. Stirring blade; 16. Foam injection pipe; 17. Outer cylinder; 18. Motor; 19. Shield support frame; 20. Mold fixing frame; 21. Slide rail; 22. Conveying device. 23. Slag outlet; 24. Rotating motor; 25. Screw auger; 26. Second foam injection hole; 27. Mating thread; 28. Thread; 29. ​​Fixing plate; 30. Jack; 31. Through hole; 32. Cutting teeth; 33. Longitudinal plate; 34. Foam preparation chamber; 35. Multi-hole inner shaft; 36. Stirring motor; 38. Seal; 39. First foam injection hole; 40. Cutter head; 41. Conveying hole; 42. Cutting blade; 44. Rotating drum; 45. Steel ball. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Reference Figure 1 As shown, the present invention provides a test device for earth pressure balance shield tunneling models, comprising:

[0034] Rack 1;

[0035] The sample mold 2 is fixed to one end of the inner cavity of the frame 1 via the mold fixing frame 20.

[0036] The movable chamber 3 is slidably connected to the end of the inner cavity of the frame 1 away from the sample mold 2. The movable chamber 3 moves along the first direction. The movable chamber 3 includes a soil chamber 4 and a foam preparation chamber 34, which are independent cavities. The soil chamber 4 is rotatably connected to a cutting part. The foam preparation chamber 34 is equipped with a foam generator and a screw conveyor. The movable chamber 3 is equipped with a test control system.

[0037] The moving mechanism on the frame 1 can control the moving chamber 3 to move towards the sample mold 2. When the moving chamber 3 and the sample mold 2 come into contact, the cutting mechanism in the soil chamber 4 comes into contact with the sample mold 2 and cuts the soil sample in the sample mold 2 into the soil chamber 4. At the same time, the foam generator can provide foam modifier to the cutting mechanism in real time when the cutting mechanism is cutting. The crushed soil entering the soil chamber 4 can be transferred to the outer wall of the device through the screw conveyor. The foam generator can also deliver foam modifier to the screw conveyor in real time. The test control system can monitor the mechanical properties of the slag in the soil chamber 4 in real time. The air compressor pump 5 is connected to the inside of the foam generator through the air inlet pipe 7. The foaming ratio of the foaming agent can be adjusted by adjusting the air pressure, thereby realizing the simulation of the effect of foam modifier on the mechanical properties of slag under different foaming ratios.

[0038] The design is further optimized so that the foam generator is fixed to the inner wall of the foam preparation chamber 34. The foam generator has three inlets, two of which are connected to the foaming agent container 8 and the additive container 10 through the injection pipe 9, respectively. The other inlet is connected to the air compressor pump 5 through the air inlet pipe 7. The foam generator has one outlet, and the outlet of the foam generator is connected to two foam injection pipes 16 through a tee. One foam injection pipe 16 is connected to the screw conveyor, and the other foam injection pipe 16 is connected to the cutting mechanism.

[0039] The foam generator can stir the foaming material fed into the foaming agent container 8 and the additive container 10 to generate a foam modifier. The foam modifier is then fed into the screw conveyor and the cutting mechanism through the foam injection pipe 16 to simulate the tunneling process under the condition of foam modifier.

[0040] The cutting mechanism is further optimized by including a porous inner shaft 35 and an outer cylinder 17. The outer cylinder 17 is fixed to the inner wall of the soil chamber 4. The porous inner shaft 35 passes through the outer cylinder 17, and several bearings are sleeved between the porous inner shaft 35 and the outer cylinder 17. A motor 18 is fixed to one side of the soil chamber 4. The output end of the motor 18 passes through the end side wall of the outer cylinder 17 and is fixed to the porous inner shaft 35. A tool assembly is fixed to the other end of the porous inner shaft 35. The inner cavity of the tool assembly is connected to the porous inner shaft 35. A first foam injection hole 39 is opened on the outer cylinder 17. The foam generator is connected to the first foam injection hole 39 through a foam injection pipe 16.

[0041] like Figure 5 As shown, the porous inner shaft 35 can be driven to rotate by turning on the motor 18. At the same time, several bearings are set between the inner shaft and the outer cylinder 17. The outer cylinder 17 is fixed to the inner wall of the soil chamber 4, which ensures that the outer cylinder 17 does not rotate when the motor 18 drives the porous inner shaft 35 to rotate. Since the tool assembly is fixed to the end of the porous inner shaft 35 away from the motor 18, the motor 18 can drive the porous inner shaft 35 to make the tool assembly rotate. The sealing member 38 set between the outer cylinder 17 and the porous inner shaft 35 forms a sealed cavity between the outer cylinder 17 and the porous inner shaft 35. The foam in the foam generator enters the inner cavity of the outer cylinder 17 through the foam injection pipe 16 and the first foam injection hole 39, and enters the tool assembly through the porous inner shaft 35. This arrangement ensures that the flow of foam is not affected when the porous inner shaft 35 and the tool assembly rotate.

[0042] Further optimization of the scheme: the tool assembly includes a tool disc 40, a feed hole 41 is opened on one side of the tool disc 40, a multi-hole inner shaft 35 is embedded in the feed hole 41, a number of cutting blades 42 are detachably connected to the circumferential side wall of the tool disc 40, the inner cavity of the cutting blade 42 is connected to the inner cavity of the tool disc 40, a through hole 31 is opened on the side wall of the cutting blade 42 facing the soil chamber 4, and a cutting tooth 32 is detachably connected to the end of the cutting blades 42 away from the tool disc 40.

[0043] like Figure 3 , Figure 4 As shown, the inner cavity of the cutter head 40 is connected to the porous inner shaft 35. Foam flows from the porous inner shaft 35 into the inner cavity of the cutter head 40 and then into the cutting blade 42. The foam is discharged from the through hole 31 on the side wall of the cutting blade 42. The number of cutting blades 42 is preferably 4 or 6. When the number of cutting blades 42 is 4, the included angle between any two adjacent cutting blades 42 is 90°. When the number of cutting blades 42 is 6, the included angle between any two adjacent cutting blades 42 is 60°. The tool opening ratio can be controlled by adjusting the number of cutting blades 42.

[0044] The screw conveyor is further optimized by including a conveying cylinder 22. One end of the conveying cylinder 22 has a thread 28 on its outer wall, and a mating thread 27 is provided on the lower side wall of the foam preparation chamber 34. One end of the conveying cylinder 22 is threadedly connected to the side wall of the foam preparation chamber 34 through the thread 28 and the mating thread 27. The inner cavity of the conveying cylinder 22 is connected to the soil chamber 4. The other end of the conveying cylinder 22 passes through the foam preparation chamber 34 and is fixedly connected to a fixing plate 29. A rotating motor 24 is provided on the outer wall of the fixing plate 29. The output end of the rotating motor 24 passes through the fixing plate 29 and is fixedly connected to an auger 25. A second foam injection hole 26 is provided on the top surface of the conveying cylinder 22 near the thread 28. The foam generator is connected to the second foam injection hole 26 through another foam injection pipe 16. A slag outlet 23 is provided on the bottom surface of the conveying cylinder 22 near the fixing plate 29.

[0045] like Figure 2 The conveying cylinder 22 shown is connected to the soil chamber 4 at one end and extends to the outside of the frame 1 at the other end. When the soil chamber 4 moves, the conveying cylinder 22 moves with it. By rotating the motor 24, the auger 25 set in the inner cavity of the conveying cylinder 22 can be driven to rotate, thereby discharging the broken soil in the soil chamber 4 from the slag outlet 23 on the bottom surface of the conveying cylinder 22. The second foam injection hole 26 set in the top surface of the conveying cylinder 22 is used to transfer the foam modifier in the foam generator into the inner cavity of the conveying cylinder 22, where it is further mixed with the soil slag in the inner cavity of the conveying cylinder 22 to improve the mechanical properties of the soil slag.

[0046] Further optimization of the design includes a fixed cylinder 12, which is fixedly connected to the foam configuration chamber 34. The three inlets and outlets are all located on the outer wall of the fixed cylinder 12. A reduction motor 13 is fixedly connected to one end of the fixed cylinder 12. The output end of the reduction motor 13 passes through the side wall of the fixed cylinder 12 and is fixedly connected to a rotating cylinder 44. Several steel balls 45 are arranged in the inner cavity of the rotating cylinder 44. The rotating cylinder 44 and the fixed cylinder 12 are rotatably connected by bearings.

[0047] like Figure 6 As shown, the three inlets on the fixed cylinder 12 can respectively introduce the foaming agent and additives from the foaming agent container 8 and the additive container 10, and at the same time introduce outside air into the fixed cylinder 12, thereby changing the air pressure inside the fixed cylinder 12. After the air pressure inside the fixed cylinder 12 changes, the foaming efficiency of the foaming agent is changed. The rotating cylinder 44 is also preferably made of a porous material, and its material is further preferably a porous acrylic material. Several steel balls 45 set in the inner cavity of the rotating cylinder 44 can fully mix the foaming agent in the fixed cylinder 12, so that the foaming agent foams more fully.

[0048] The scheme is further optimized. The moving mechanism includes a slide rail 21, which is fixedly connected to the inner cavity of the frame 1. The moving chamber 3 is slidably connected to the slide rail 21 through the shield support frame 19. A jack 30 is fixedly connected to the side of the inner cavity of the frame 1 away from the sample mold 2. The output end of the jack 30 is fixedly connected to the side wall of the moving chamber 3.

[0049] By activating the jack 30, the movable chamber 3 can be moved on the slide rail 21, thereby bringing the movable chamber 3 into contact with the sample mold 2 and cutting the sample mold 2.

[0050] Further optimization of the scheme: The test control system includes two stirring motors 36 fixed above and below the side wall of the foam preparation chamber 34, respectively. The output ends of the two stirring motors 36 pass through the side wall of the foam preparation chamber 34 and are respectively fixed with stirring blades 15. The stirring blades 15 are located inside the soil chamber 4. Sensors 14 are also fixed on the stirring blades 15. The sensors 14 are connected to the PC terminal for signal connection.

[0051] Reference Figure 7 As shown, the two stirring blades 15 installed on the side wall of the longitudinal plate 33 are connected to the PC via the torque sensor 14 and the data transmitter. Both can detect the rheological parameters of the slag in the soil chamber 4. Considering the influence of the slag's self-weight settling on the experiment during actual construction, the upper stirring blade 15 is used to balance the error, while the torque measured by the lower stirring blade 15 is closer to the actual rheological parameters of the slag.

[0052] Further optimization of the scheme includes a pressure simulation system, which includes an air pump 11 fixed to the inner wall of the foam configuration chamber 34. The air pump 11 is connected to the soil chamber 4 via an air line 6.

[0053] The air pump 11 installed can pump external air into the soil chamber 4 and provide air pressure to the soil chamber 4, thereby simulating tunneling construction when the soil chamber 4 is not fully filled.

[0054] In a further optimized design, a seal 38 is provided between the porous inner shaft 35 and the outer cylinder 17, with the sidewall of the seal 38 abutting against the tool assembly.

[0055] The seal 38 can seal the gap between the outer cylinder 17 and the tool assembly, ensuring that the foam modifier is completely introduced into the tool assembly from the porous inner shaft 35.

[0056] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0057] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A test device for earth pressure balance shield tunneling models, characterized in that, include: Rack (1); The sample mold (2) is fixed to one end of the inner cavity of the frame (1) via a mold fixing frame (20); The moving chamber (3) is slidably connected to one end of the inner cavity of the frame (1) away from the sample mold (2), and the moving chamber (3) moves along a first direction; the moving chamber (3) includes a soil chamber (4) and a foam preparation chamber (34), and the soil chamber (4) and the foam preparation chamber (34) are independent cavities; the soil chamber (4) is rotatably connected to a cutting part, the foam preparation chamber (34) is equipped with a foam generator and a screw conveyor, and the moving chamber (3) is equipped with a test control system; The foam generator is fixed to the inner wall of the foam preparation chamber (34). The foam generator has three inlets, two of which are connected to the foaming agent container (8) and the additive container (10) respectively through injection pipes (9), and the other inlet is connected to the air compressor pump (5) through the air inlet pipe (7). The foam generator has one outlet, and the outlet of the foam generator is connected to two foam injection pipes (16) respectively through a tee. One of the foam injection pipes (16) is connected to the screw conveyor, and the other foam injection pipe (16) is connected to the cutting mechanism. The test control system includes two stirring motors (36) respectively fixed above and below the side wall of the foam configuration chamber (34). The output ends of the two stirring motors (36) pass through the side wall of the foam configuration chamber (34) and are respectively fixed with stirring blades (15). The stirring blades (15) are located inside the soil chamber (4). A torque sensor (14) is also fixed on the stirring blades (15). The torque sensor (14) is connected to the PC terminal signal.

2. The earth pressure balance shield tunneling model test device according to claim 1, characterized in that: The cutting mechanism includes a porous inner shaft (35) and an outer cylinder (17). The outer cylinder (17) is fixed to the inner wall of the soil chamber (4). The porous inner shaft (35) passes through the outer cylinder (17), and several bearings are sleeved between the porous inner shaft (35) and the outer cylinder (17). An electric motor (18) is fixed to one side of the soil chamber (4). The output end of the electric motor (18) passes through the end side wall of the outer cylinder (17) and is fixed to the porous inner shaft (35). A tool assembly is fixed to the other end of the porous inner shaft (35). The inner cavity of the tool assembly is connected to the porous inner shaft (35). A first foam injection hole (39) is opened on the outer cylinder (17). The foam generator is connected to the first foam injection hole (39) through a foam injection pipe (16).

3. The earth pressure balance shield tunneling model test device according to claim 2, characterized in that: The tool assembly includes a cutter head (40), a feed hole (41) is provided on one side of the cutter head (40), the multi-hole inner shaft (35) is embedded in the feed hole (41), a plurality of cutting blades (42) are detachably connected to the circumferential side wall of the cutter head (40), the inner cavity of the cutting blade (42) is connected to the inner cavity of the cutter head (40), a through hole (31) is provided on the side wall of the cutting blade (42) facing the soil chamber (4), and a cutting tooth (32) is detachably connected to the end of the plurality of cutting blades (42) away from the cutter head (40).

4. The earth pressure balance shield tunneling model test device according to claim 3, characterized in that: The screw conveyor includes a conveying cylinder (22). One end of the conveying cylinder (22) has a thread (28) on its outer wall. The lower side wall of the foam preparation chamber (34) has a mating thread (27). One end of the conveying cylinder (22) is threaded to the side wall of the foam preparation chamber (34) through the thread (28) and the mating thread (27). The inner cavity of the conveying cylinder (22) is connected to the soil chamber (4). The other end of the conveying cylinder (22) passes through the foam preparation chamber (34) and is fixedly connected to a... A fixed plate (29) is provided with a rotating motor (24) on its outer wall. The output end of the rotating motor (24) passes through the fixed plate (29) and is fixedly connected to an auger (25). A second foam injection hole (26) is provided on the top surface of the conveying cylinder (22) near the thread (28). The foam generator is connected to the second foam injection hole (26) through another foam injection pipe (16). A slag outlet (23) is provided on the bottom surface of the conveying cylinder (22) near the fixed plate (29).

5. The earth pressure balance shield tunneling model test device according to claim 4, characterized in that: The foam generator also includes a fixed cylinder (12), which is fixedly connected to the foam configuration chamber (34). The three inlets and the outlet are all opened on the outer wall of the fixed cylinder (12). A reduction motor (13) is fixedly connected to one end of the fixed cylinder (12). The output end of the reduction motor (13) passes through the side wall of the fixed cylinder (12) and is fixedly connected to a rotating cylinder (44). The inner cavity of the rotating cylinder (44) is provided with several steel balls (45). The rotating cylinder (44) and the fixed cylinder (12) are rotatably connected by bearings.

6. The earth pressure balance shield tunneling model test device according to claim 5, characterized in that; It also includes: a moving mechanism, including a slide rail (21), the slide rail (21) being fixedly connected to the inner cavity of the frame (1), the moving chamber (3) being slidably connected to the slide rail (21) via a shield support frame (19), and a jack (30) being fixedly connected to the side of the inner cavity of the frame (1) away from the sample mold (2), the output end of the jack (30) being fixedly connected to the side wall of the moving chamber (3).

7. The earth pressure balance shield tunneling model test device according to claim 1, characterized in that, Also includes: The air pressure simulation system includes an air pump (11) fixed to the inner wall of the foam configuration chamber (34), and the air pump (11) is connected to the soil chamber (4) via an air line (6).

8. The earth pressure balance shield tunneling model test device according to claim 2, characterized in that: A sealing element (38) is also provided between the porous inner shaft (35) and the outer cylinder (17), and the side wall of the sealing element (38) abuts against the tool assembly.

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