Simulation device and method for soil pressure balance shield mud cake formation and muck improvement test

Abstract

The invention relates to the technical field of underground engineering shield mud cake formation, and discloses a simulation device and method for an earth pressure balance shield mud cake formation and muck improvement test. The technical problem that in the prior art, soil pressure shield mud cakes and the mud cake removing effect are difficult to conduct on-site tests is solved. The device comprises a simulated soil box, a cutterhead assembly is arranged in the machine body and comprises a cutterhead, a motor for driving the cutterhead to rotate and a driving main shaft; the pressure simulation assembly comprises a telescopic hydraulic jack, the telescopic hydraulic jack comprises a first force application unit and a second force application unit, the first force application unit is connected with the motor, and the second force application unit is connected with the pressurizing plate. According to the invention, the loss condition and loss amount of reagents such as a foaming agent and a stripping agent after injection under different stratum conditions can be clearly observed, so that the loss amount and the effect of the reagents are explored, and the method has important reference significance for researching the dosage, the action mechanism and the like of the reagents in different stratums.

Description

Technical Field

[0001] This invention relates to the field of shield tunneling mud cake technology in underground engineering, and in particular to a simulation device and method for testing earth pressure balance shield tunneling mud cake and slag improvement. Background Technology

[0002] When earth pressure balance (EPB) tunnel boring machines (TBMs) encounter soils with high water content and strong cohesion during their advancement, a dense mud film forms from the mixture of water and sticky substances, adhering to the TBM cutterhead and gradually thickening to form a mud cake. This hinders the normal progress of TBM construction, significantly impacting efficiency, safety, and cost. While some researchers have conducted studies on mud cake formation and removal in EPB TBMs, the effectiveness of these studies is difficult to demonstrate through field trials. Therefore, indoor simulation experiments can be used to simulate the effects of cutterhead mud cake formation and soil improvement.

[0003] Chinese patent application CN108266199A discloses an invention patent and method for simulating soil cake formation on the cutterhead of an earth pressure balance shield tunnel. The device has an openable and closable door at the top, and horizontal jacks on the outside of the pressure plate. The cutterhead is driven to rotate by a rotary motor via a drive shaft, which is equipped with a sensor array. Chinese utility model patent application CN218003212U discloses a utility model patent for simulating soil cake formation on the cutterhead of an earth pressure balance shield tunnel. This device rotates a threaded rod to drive a rotating pressure block. As the threaded ring gradually moves outward, the rotating pressure block gradually enters the mounting groove. The rotating threaded shaft drives the threaded tube and sliding plate to move. The sliding plate movement drives the drive motor, drive shaft, and fixed cutterhead to move until the fixed cutterhead moves the movable cover away from the experimental cylinder. Then, an electric telescopic rod is activated to move the extrusion plate towards the slide rail until the soil inside the experimental cylinder is completely extruded.

[0004] Currently, existing earth pressure balance shield tunneling mud cake simulation devices lack research on the impact of different geological formations on reagent loss and effectiveness after the injection of stripping agents and foaming agents. Therefore, it is necessary to optimize the design of earth pressure balance shield tunneling simulation test devices in this regard. Summary of the Invention

[0005] In view of the above technical problems, this disclosure provides a simulation device and method for testing mud cake formation and soil improvement in earth pressure balance (EPB) shield tunneling machines. This solves the problem in existing technologies where, when EPB shield tunneling machines encounter soil with high water content and strong viscosity during advancement, a dense mud film formed by the mixture of water and sticky substances adheres to the shield machine cutterhead and gradually thickens to form mud cake, thus hindering the normal progress of shield tunneling. This situation has a significant impact on the efficiency, safety, and cost of shield tunneling. While some scholars have conducted relevant research on mud cake formation and removal in EPB shield tunneling machines, the effectiveness of these studies has been difficult to demonstrate in field trials.

[0006] According to one aspect of this disclosure, a simulation device for testing earth pressure balance shield tunneling mud cake and slag improvement is provided, comprising a simulated soil box; a cutterhead assembly is disposed inside the simulated soil box, the cutterhead assembly comprising a cutterhead and a motor and a drive spindle for driving the cutterhead to rotate; It also includes a pressure simulation component, which includes a telescopic hydraulic jack. The hydraulic jack includes a first force application unit and a second force application unit. The first force application unit is connected to a motor to push the cutterhead assembly into the simulated soil box, and the second force application unit is connected to a pressure plate to apply pressure to the soil filled into the simulated soil box. At least one side wall of the simulated soil box is a transparent side wall, and a modifier seepage observation component is installed on the transparent side wall. A drain outlet for collecting and discharging seepage liquid is provided at the bottom of the simulated soil box, and a graduated cylinder for measuring the volume of seepage liquid is arranged below the drain outlet.

[0007] In some embodiments of this disclosure, the motor is provided with casters at its bottom.

[0008] In some embodiments of this disclosure, a torque sensor is mounted on the drive spindle.

[0009] In some embodiments of this disclosure, a soil chamber simulation room is provided behind the cutter head, and the soil chamber simulation room is separated from the main body of the simulated soil box by a partition, and the partition is connected to the drive spindle by a sliding bearing.

[0010] In some embodiments of this disclosure, a rubber sealing ring is provided between the partition and the inner wall of the simulated soil box; a slag discharge pipe is connected to the lower part of the soil chamber simulation chamber.

[0011] In some embodiments of this disclosure, the slag discharge pipe is equipped with a valve, and the slag discharge pipe is a transparent flexible hose.

[0012] In some embodiments of this disclosure, the top of the simulated soil box is provided with an opening and closing door, the drainage outlet is located below the groove area of ​​the side wall of the simulated soil box, and the opening and closing door is located above the groove area.

[0013] In some embodiments of this disclosure, a foam generating assembly is also included, which includes a foam generator, a foaming agent supply unit connected to the foam generator, an air supply unit, and a water supply unit. The output end of the foam generator is connected to the front of the cutter head via a pipe. A liquid flow meter, a gas flow meter, a solution metering regulating valve, and an air metering regulating valve are provided on the pipe.

[0014] A test method for earth pressure balance shield tunneling mud cake and spoil soil improvement includes the following steps: S1. Test preparation and soil filling: According to the test strata, the test soil is filled into the simulated soil box by opening and closing the compartment door. After filling, the compartment door is closed. S2, Formation pressure simulation: Activate the second force application unit of the pressure simulation component to apply a preset pressure to the soil in the simulated soil box through the pressure plate to simulate real formation soil pressure; S3, Shield tunneling: After reaching the preset earth pressure, the motor is started to drive the cutterhead to rotate, and at the same time the first force application unit of the pressure simulation component is started to push the cutterhead assembly into the soil to simulate the shield tunneling process; S4. Tunneling process monitoring: During the tunneling process, the torque changes of the cutterhead are monitored and recorded in real time by the torque sensor on the drive spindle. The fluid plastic state of the discharged slag is observed through a transparent slag discharge pipe, and the valves on the slag discharge pipe are controlled to simulate different slag discharge speeds. S5. Conduct soil improvement tests or mud cake soaking and removal tests: Depending on the experimental objective, perform either of the following two tests or in sequence: a. Slag Improvement Test: During the tunneling process, slag improver was injected into the soil chamber simulation chamber through a foam generator, and the effects of the slag improver on the slag improvement effect, slag discharge status and cutterhead mud cake formation were observed. b. Mud cake removal test: First, a stable mud cake is formed in front of the cutterhead by controlling the tunneling parameters; then, tunneling is stopped, the opening and closing chamber door is opened, and a mud cake removal agent is injected quantitatively into the mud cake in front of the cutterhead. S6. Leakage Analysis: After injecting the slag amendment or mud cake remover, perform the following operations: a. By simulating the transparent wall of the soil box, the seepage path, seepage rate, and dissolution and peeling process of the soil amendment or mud cake remover can be observed intuitively. b. Collect and measure the liquid seeping from the soil using a graduated cylinder located below the drain outlet; c. Record the volume V of the injected soil conditioner or mud cake remover, and the volume V of reagent lost through the drain outlet at different times t. t ; d. According to the formula Calculate the seepage rate L of the soil amendment or mud cake remover, and analyze the relationship between the seepage rate, seepage rate and the actual removal effect of the mud cake. S7. Post-test processing: After the test, open the opening and closing chamber door to clean the remaining slag in the simulated soil box, and reset each jack and cutter head component to its initial state.

[0015] The beneficial effects of this invention are as follows: At least one sidewall of the simulated soil chamber is transparent, enabling visualization and real-time monitoring of the experimental process. Operators can directly observe the cutterhead's excavation status, soil flow and compaction, the formation and evolution of mud cake on the cutterhead surface, and the diffusion and infiltration behavior of the soil conditioner. This significantly enhances the intuitiveness of the experiment and the richness of the data collected, providing direct evidence for qualitative analysis.

[0016] A modifier seepage monitoring component, including a drainage outlet and a measuring cylinder below, is installed on a transparent sidewall. This solves the problem that existing technologies cannot quantitatively assess the loss of modifiers in the formation. It enables the quantitative collection and measurement of fluid seeping from the soil, making it possible to calculate the seepage rate. Through quantitative data analysis, the effective utilization rate of modifiers under different formation conditions can be scientifically evaluated, providing direct experimental evidence for optimizing injection ratios and reducing material costs in engineering projects.

[0017] The pressure simulation component employs two independent force application units, enabling independent control and simulation of tunneling thrust and soil chamber pressure. The second force application unit simulates at-rest earth pressure through a pressure plate, more realistically reproducing the constraint state of the strata in front of the tunnel boring machine (TBM); the first force application unit independently drives the cutterhead to tunnel, simulating the TBM's propulsion force. This allows for independent and precise adjustment of test parameters, enabling the simulation of more complex construction conditions, and resulting in more representative and instructive test results.

[0018] A torque sensor is installed on the drive spindle. This sensor can monitor the torque changes of the cutterhead in real time and accurately during the tunneling process. The torque value is a key dynamic parameter reflecting the degree of mud cake formation on the cutterhead, the effect of soil amendment, and the tunneling resistance. By analyzing the torque data, the formation and development stages of mud cake and the effect of different amendments on reducing the load on the cutterhead can be quantitatively assessed, providing objective quantitative indicators for judging the construction status and the effectiveness of amendments.

[0019] The design of the soil chamber simulation chamber and muck discharge pipeline: A partition and sealing ring form a relatively closed soil chamber behind the cutterhead, simulating the pressure-holding environment of a shield tunneling soil chamber and preventing the amendment from leaking from behind the cutterhead, ensuring the accuracy of the test. The transparent flexible muck discharge pipeline with valves: The valves can precisely control the muck discharge speed and soil chamber pressure, simulating different tunneling equilibrium states; the transparent flexible hose allows direct observation of the fluidity, moisture content, and homogeneity of the discharged muck, providing the most intuitive window for evaluating the muck amendment effect.

[0020] The foam generation component enables precise injection of the slag amendment. By adjusting the flow rate and ratio of the solution and air, the foaming ratio, injection rate, and injection pressure can be precisely controlled, thereby systematically studying the effects of different foam parameters on the slag amendment effect and anti-caking performance, enabling the experiment to move from qualitative to quantitative research.

[0021] The groove forms a natural water collection channel and observation window, facilitating the collection of seepage fluid to the drain outlet and allowing for easy observation of the mud cake condition in the central area on the front of the cutterhead. The opening and closing chamber door provides convenient access for backfilling, cleaning, and intervention operations. During the soaking chamber test, the stripping agent can be directly injected into the front of the cutterhead without disassembling the device, greatly improving the convenience and efficiency of the test operation. Attached Figure Description

[0022] Figure 1 A schematic diagram of the simulation device used for earth pressure balance shield tunneling mud cake and slag improvement tests; Figure 2 A schematic diagram of the cutterhead structure of the simulation device used for earth pressure balance shield tunneling mud cake and slag improvement tests; The components in the diagram are named as follows: 1-Hydraulic jack, 2-Motor, 3-Supply valve, 4-Foam generator, 5-Rubber sealing ring, 6-Cutter head, 7-Drain outlet, 8-Measuring cylinder, 9-Slag discharge pipe, 10-Simulated soil box, 11-Torque sensor, 12-Opening and closing chamber door, 13-Cutter, 14-Cutter head opening. Detailed Implementation

[0023] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Example 1

[0024] This example discloses a simulation device and method for testing earth pressure balance shield tunneling mud cake and spoil improvement, see figure. It includes a simulated soil box 10; a cutter head assembly is set inside the simulated soil box 10, the cutter head assembly includes a cutter head 6 and a motor and drive spindle for driving the cutter head 6 to rotate; a cutter 13 is installed on the cutter head 6, and a cutter head opening 14 is opened on the cutter head 6.

[0025] It also includes a pressure simulation component, which includes a telescopic hydraulic jack 1. The hydraulic jack 1 includes a first force application unit and a second force application unit. The first force application unit is connected to a motor 2 to push the cutterhead assembly into the simulated soil box 10 for excavation. The second force application unit is connected to a pressure plate to apply pressure to the soil filled into the simulated soil box 10. At least one side wall of the simulated soil tank 10 is a transparent side wall, and a modifier seepage observation component is installed on the transparent side wall. A drain outlet 7 for collecting and draining seepage liquid is provided at the bottom of the simulated soil tank 10, and a measuring cylinder 8 for measuring the volume of seepage liquid is arranged below the drain outlet 7.

[0026] The motor 2 is equipped with casters at the bottom.

[0027] A torque sensor 11 is installed on the drive spindle.

[0028] The soil chamber simulation room is located behind the cutter head 6. The soil chamber simulation room is separated from the main body of the simulated soil box 10 by a partition. The partition is connected to the drive spindle by a sliding bearing.

[0029] A rubber sealing ring 5 is provided between the partition and the inner wall of the simulated soil box 10; the lower part of the soil chamber simulation room is connected to the slag discharge pipe 9.

[0030] A valve is installed on the slag discharge pipe 9, and the slag discharge pipe 9 is made of transparent flexible hose.

[0031] The top of the simulated soil tank 10 is provided with an opening and closing door 12, the drainage outlet 7 is located below the groove area on the side wall of the simulated soil tank 10, and the opening and closing door 12 is located above the groove area.

[0032] It also includes a foam generating assembly, which includes a foam generator 4, a foaming agent supply unit, an air supply unit, and a water supply unit connected to the foam generator 4. The output end of the foam generator 4 is connected to the front of the cutter head 6 through a pipe. The pipe is equipped with a liquid flow meter, a gas flow meter, a solution metering regulating valve, and an air metering regulating valve.

[0033] A supply valve 3 is installed on the flow pipe of the foam generator 4.

[0034] A test method for earth pressure balance shield tunneling mud cake and spoil soil improvement includes the following steps: S1. Test preparation and soil filling: According to the test strata, the test soil is filled into the simulated soil box 10 through the opening and closing door 12. After filling is completed, the opening and closing door 12 is closed. S2, Formation pressure simulation: Activate the second force application unit of the pressure simulation component to apply a preset pressure to the soil in the simulation soil box 10 through the pressure plate to simulate the real formation soil pressure; S3, Shield tunneling: After reaching the preset earth pressure, start motor 2 to drive cutterhead 6 to rotate, and at the same time start the first force application unit of the pressure simulation component to push the cutterhead component into the soil to simulate the shield tunneling process; S4. Tunneling process monitoring: During the tunneling process, the torque sensor 11 on the drive spindle monitors and records the torque changes of the cutterhead 6 in real time. The fluid plastic state of the discharged slag is observed through the transparent slag discharge pipe 9, and the valves on the slag discharge pipe 9 are controlled to simulate different slag discharge speeds. S5. Conduct soil improvement tests or mud cake soaking and removal tests: Depending on the experimental objective, perform either of the following two tests or in sequence: a. Slag Improvement Test: During the tunneling process, slag improver was injected into the soil chamber simulation chamber through foam generator 4, and the effects of slag improver on slag improvement effect, slag discharge status and cutterhead 6 mud cake formation were observed. b. Mud cake removal test: First, a stable mud cake is formed in front of the cutterhead 6 by controlling the tunneling parameters; then, the tunneling is stopped, the opening and closing chamber door 12 is opened, and a mud cake removal agent is injected quantitatively into the mud cake in front of the cutterhead 6. S6. Leakage Analysis: After injecting the slag amendment or mud cake remover, perform the following operations: a. By using the transparent wall of the simulated soil box 10, the seepage path, seepage rate, and dissolution and peeling process of the soil amendment or mud cake remover can be observed directly. b. Collect and measure the liquid seeping from the soil through the measuring cylinder 8 located below the drain outlet 7; c. Record the volume V of the injected soil conditioner or mud cake remover, and the volume V of reagent lost through drain outlet 7 at different times t. t ; d. According to the formula Calculate the seepage rate L of the soil amendment or mud cake remover, and analyze the relationship between the seepage rate, seepage rate and the actual removal effect of the mud cake. S7. Post-test processing: After the test, open the opening and closing chamber door 12 to clean the remaining slag in the simulated soil box 10, and reset each jack and cutter head 6 component to the initial state.

[0035] Although some preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0036] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this application and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A simulation device and method for testing earth pressure balance shield tunneling mud cake and slag improvement, characterized in that: It includes a simulated soil box; a cutterhead assembly is installed inside the simulated soil box, and the cutterhead assembly includes a cutterhead and a motor and a drive spindle for driving the cutterhead to rotate; It also includes a pressure simulation component, which includes a telescopic hydraulic jack. The hydraulic jack includes a first force application unit and a second force application unit. The first force application unit is connected to a motor to push the cutterhead assembly into the simulated soil box, and the second force application unit is connected to a pressure plate to apply pressure to the soil filled into the simulated soil box. At least one side wall of the simulated soil box is a transparent side wall, and a modifier seepage observation component is installed on the transparent side wall. A drain outlet for collecting and discharging seepage liquid is provided at the bottom of the simulated soil box, and a graduated cylinder for measuring the volume of seepage liquid is arranged below the drain outlet.

2. The simulation device for testing earth pressure balance shield tunneling mud cake and slag improvement as described in claim 1, characterized in that: The motor is equipped with casters at the bottom.

3. The simulation device for testing earth pressure balance shield tunneling mud cake and slag improvement as described in claim 1, characterized in that: A torque sensor is installed on the drive spindle.

4. The simulation device for testing earth pressure balance shield tunneling mud cake and slag improvement as described in claim 1, characterized in that: A soil chamber simulation room is provided behind the cutter head. The soil chamber simulation room is separated from the main body of the simulated soil box by a partition. The partition is connected to the drive spindle by a sliding bearing.

5. The simulation device for testing earth pressure balance shield tunneling mud cake and slag improvement as described in claim 4, characterized in that: A rubber sealing ring is provided between the partition and the inner wall of the simulated soil box; a slag discharge pipe is connected to the lower part of the soil chamber simulation room.

6. The simulation device for testing earth pressure balance shield tunneling mud cake and slag improvement as described in claim 5, characterized in that: The slag discharge pipe is equipped with a valve and is made of a transparent flexible hose.

7. The simulation device for earth pressure balance shield tunneling mud cake and spoil soil improvement test as described in claim 1, characterized in that: The simulated soil tank is equipped with an opening and closing door on its top, and the drainage outlet is located below the groove area on the side wall of the simulated soil tank, while the opening and closing door is located above the groove area.

8. The simulation device for testing earth pressure balance shield tunneling mud cake and spoil as described in claim 1, characterized in that: It also includes a foam generating assembly, which includes a foam generator, a foaming agent supply unit connected to the foam generator, an air supply unit, and a water supply unit. The output end of the foam generator is connected to the front of the cutter head through a pipe. The pipe is equipped with a liquid flow meter, a gas flow meter, a solution metering regulating valve, and an air metering regulating valve.

9. A test method for earth pressure balance shield tunneling mud cake and slag improvement, applicable to the simulation device used for earth pressure balance shield tunneling mud cake and slag improvement tests as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Test preparation and soil filling: According to the test strata, the test soil is filled into the simulated soil box by opening and closing the compartment door. After filling, the compartment door is closed. S2, Formation pressure simulation: Activate the second force application unit of the pressure simulation component to apply a preset pressure to the soil in the simulated soil box through the pressure plate to simulate real formation soil pressure; S3, Shield tunneling: After reaching the preset earth pressure, the motor is started to drive the cutterhead to rotate, and at the same time the first force application unit of the pressure simulation component is started to push the cutterhead assembly into the soil to simulate the shield tunneling process; S4. Tunneling process monitoring: During the tunneling process, the torque changes of the cutterhead are monitored and recorded in real time by the torque sensor on the drive spindle. The fluid plastic state of the discharged slag is observed through a transparent slag discharge pipe, and the valves on the slag discharge pipe are controlled to simulate different slag discharge speeds. S5. Conduct soil improvement tests or mud cake soaking and removal tests: Depending on the experimental objective, perform either of the following two tests or in sequence: a. Slag Improvement Test: During the tunneling process, slag improver was injected into the soil chamber simulation chamber through a foam generator, and the effects of the slag improver on the slag improvement effect, slag discharge status and cutterhead mud cake formation were observed. b. Mud cake removal test: First, a stable mud cake is formed in front of the cutterhead by controlling the tunneling parameters; Subsequently, the tunneling was stopped, the opening and closing chamber door was opened, and a measured amount of mud cake removal agent was injected into the mud cake in front of the cutterhead; S6. Leakage Analysis: After injecting the slag amendment or mud cake remover, perform the following operations: a. By simulating the transparent wall of the soil box, the seepage path, seepage rate, and dissolution and peeling process of the soil amendment or mud cake remover can be observed intuitively. b. Collect and measure the liquid seeping from the soil using a graduated cylinder located below the drain outlet; c. Record the volume V of the injected soil conditioner or mud cake remover, and the volume V of reagent lost through the drain outlet at different times t. t ; d. According to the formula Calculate the seepage rate L of the soil amendment or mud cake remover, and analyze the relationship between the seepage rate, seepage rate and the actual removal effect of the mud cake. S7. Post-test processing: After the test, open the opening and closing chamber door to clean the remaining slag in the simulated soil box, and reset each jack and cutter head component to its initial state.

Images