Earth pressure balance shield mudstone stratum tunneling muck improvement method

Abstract

The invention belongs to the technical field of tunneling muck improvement and water adding, and particularly discloses an earth pressure balance shield mudstone stratum tunneling muck improvement method which comprises the following steps: S1, carrying out stratum analysis on a mudstone stratum, and selecting an improvement material; s2, a frequency converter is additionally arranged on an original bentonite pump, and the frequency converter is integrated with a central control system of the shield tunneling machine through an intelligent control interface; s3, one water tank and two piston pumps are additionally arranged, meanwhile, a frequency converter, a flow sensor and a pressure sensor are arranged, and the intelligent water flow dynamic regulation and control technology is used for controlling the water adding flow in real time; s4, in the tunneling process of the shield tunneling machine, the muck is improved in real time through a water injection nozzle in front of a cutter head of the shield tunneling machine and a bentonite water adding injection line; and S5, after the shield tunneling machine completes tunneling of each ring, the improvement effect of the cutterhead and the muck is evaluated, system maintenance is carried out, and a water adding pipeline is checked and cleaned. The mud rock stratum muck improvement effect can be improved, and water adding flow and water pressure control is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of improving and adding water to excavation debris, and in particular to a method for improving excavation debris in mudstone strata using an earth pressure balance shield. Background Art

[0002] The characteristic of earth pressure balance shield is to use the excavated soil as the medium to support the stability of the excavation surface. Therefore, the soil as the supporting medium is required to have good plastic deformation and soft consistency, as well as small internal friction angle and low permeability. Since ordinary soil cannot fully meet these characteristics, it is necessary to improve it. The technical point is to inject water, bentonite slurry, clay, polymer or foam and other mixed additives into the front of the cutter head and the soil bin, and after strong stirring, improve the plasticity and fluidity of the excavated soil and reduce the water permeability of the soil.

[0003] However, since the cores of mudstone formations are mostly columnar and blocky, soft, easily weathered, easily softened when exposed to water, and have a low water content, conventional improvement methods such as foaming agents, polymers, and water have limitations. Even if a foam with a small foaming ratio is selected and the injection rate is increased, the cutterhead still has the problem of mud cake.

[0004] Although dispersants and polymers are more effective in viscous formations such as mudstone, it takes a certain amount of time for dispersants to produce effective chemical reactions. Therefore, the importance of adding water to the cutterhead and soil bin is the focus of shield tunneling waste improvement in mudstone formations.

[0005] At present, the shield machine generally uses a bentonite pump to add water to the soil improvement, and the 1st line of foam is changed to bentonite to assist the soil bin to add water. When using the bentonite pump to add water, the foam delivery pump and the corresponding ball valve that share the same pipeline with the bentonite delivery pipeline must be closed before use. The bentonite is pressed into the cutter head, soil bin and screw conveyor through the delivery pump to achieve the purpose of improving the soil. However, the water addition capacity of the 1st line bentonite pump is 15m 3 / h, which cannot meet the requirements of shield machine for mudstone strata excavation with an injection volume of 30m per ring in 30min 3 ~40m 3 There is a need for water addition, and there is no water addition on the cutter disc panel.

[0006] Based on this, it is urgent to provide a method for improving the excavation waste soil of mudstone strata in an earth pressure balance shield to solve the above technical problems. Summary of the invention

[0007] The invention provides a method for improving excavation debris in mudstone strata by an earth pressure balance shield, aiming to improve the improvement effect of excavation debris in mudstone strata and realize the flow rate and water pressure control of water addition.

[0008] The present invention is achieved through the following technical solution: A method for improving soil excavation in mudstone strata by an earth pressure balance shield, comprising the following steps:

[0009] S1. Conduct stratigraphic analysis on mudstone formations and select improved materials;

[0010] S2. Add a frequency converter to the original bentonite pump. The frequency converter is integrated with the central control system of the shield machine through an intelligent control interface to realize the control of the bentonite pump.

[0011] S3, add a water tank, two piston pumps of the same specifications as the bentonite pump, and set up frequency converters, flow sensors and pressure sensors, and use intelligent water flow dynamic control technology to control the water flow in real time;

[0012] S4. During the tunneling of the shield machine, the slag is improved in real time through the water spray port in front of the shield machine cutter head and the bentonite water injection line;

[0013] S5. After each tunneling ring is completed, the improvement effect of the cutterhead and slag is evaluated, system maintenance is carried out, and the water supply pipeline is checked and cleaned.

[0014] Furthermore, the formation analysis in S1 includes formation property evaluation and data analysis;

[0015] The formation property assessment includes conducting geological surveys on mudstone formations to assess the physical and chemical properties of mudstone, including hardness, water content, viscosity and weathering susceptibility; the data analysis includes analyzing the collected formation data to determine the variation range and geological conditions of the mudstone;

[0016] The improved materials include bentonite slurry, clay, high molecular polymer and specially formulated foam.

[0017] Further, in S2, the bentonite pump is controlled by a frequency converter, including the following steps:

[0018] S2.1. Select the inverter of corresponding specifications according to the power and operation requirements of the bentonite pump and test its compatibility;

[0019] S2.2. Install the frequency converter on the control panel of the bentonite pump;

[0020] S2.3, configure the intelligent control interface of the inverter to realize data exchange with the central control system of the shield machine through the CAN communication protocol;

[0021] S2.4. Set the starting frequency, acceleration time and deceleration time of the inverter according to the working requirements of the bentonite pump;

[0022] The frequency adjustment formula of the frequency converter for the bentonite pump is as follows:

[0023] f=f0+K p ×(SP-PV);

[0024] Where, f is the inverter output frequency; f0 is the reference frequency; K p is the proportional gain; SP is the set point; PV is the process variable.

[0025] Furthermore, the intelligent water flow dynamic control technology is implemented based on variable frequency control technology and PID control algorithm. The intelligent water flow dynamic control technology realizes real-time control of water flow, including the following steps:

[0026] S3.1. Define system variables, including real-time flow Q(t), target flow Q set (t), pump inlet pressure and outlet pressure, initialization of PID controller parameters, flow equation parameters, pump characteristic parameters and system resistance parameters;

[0027] S3.2, use flow sensors and pressure sensors to monitor real-time flow, pump inlet and outlet pressures;

[0028] S3.3, calculate the flow error e(t), and use the PID controller to determine the control output u(t) through the proportion, integration and differentiation of the calculated flow error;

[0029] S3.4, adjust the pump speed to match the target flow rate according to the control output u(t), and monitor whether the relationship between the actual flow rate and the system pressure conforms to the theoretical and actual working curves;

[0030] S3.5. Use real-time data feedback from flow sensors and pressure sensors to adjust K p , K i , K d , optimize the control effect, consider the influence of system resistance on control, and adjust the total pressure loss ΔP;

[0031] Among them, K p is the proportional gain, which is directly multiplied by the error and responds to the immediate deviation; K i is the integral gain; K d is the differential gain.

[0032] Furthermore, the mathematical formula involved in calculating the flow error e(t) in S3.3 is as follows:

[0033] e(t)=Q set (t)-Q(t);

[0034] Among them, Q set (t) is the target flow; Q(t) is the real-time flow; e(t) is the difference between the target flow and the real-time flow;

[0035] The specific mathematical formula involved in using the PID controller to determine the control output u(t) by calculating the proportion, integration and differentiation of the flow error is as follows:

[0036]

[0037] u(t) represents the control output of the PID controller.

[0038] Further, the relationship between the actual flow rate and the system pressure monitored in S3.4 involves the relationship between the flow rate Q and the system pressure difference ΔP and the performance of the pump;

[0039] The mathematical model formula involved in the relationship between the flow rate Q and the system pressure difference ΔP is as follows:

[0040]

[0041] Among them, C d is the flow coefficient; A is the pipe cross-sectional area; ρ is the water density;

[0042] The characteristic curve equation involved in the performance of the pump is as follows:

[0043] H=H0-kQ 2 ;

[0044] Where H is the total head generated by the pump; H0 is the maximum head of the pump at zero flow; k is a constant related to the pump characteristics; and Q is the flow rate of the pump.

[0045] Furthermore, in S3.5, real-time data feedback from the flow sensor and pressure sensor is used to adjust K p Quick response error, adjust K i Eliminate long-term errors and adjust K d To prevent overshoot and system oscillation, the mathematical formula involved in adjusting the total pressure loss ΔP is as follows:

[0046]

[0047] Where ΔP is the total pressure loss; f is the friction factor; L is the pipe length; D is the pipe diameter; v is the flow velocity; K r is the local resistance coefficient, and ρ is the density of the improved medium.

[0048] Furthermore, in S4, the real-time improvement of the slag soil through the water spray port in front of the shield machine cutter head and the bentonite water injection line includes the following steps:

[0049] S4.1. Determine the specific needs for soil improvement, including increasing the plasticity of the soil, reducing its permeability, or improving its fluidity;

[0050] S4.2. Calculate the mixing ratio and injection volume of water and bentonite;

[0051] S4.3, configure the water spray port and injection line, and set the parameters of the water spray port in front of the cutter disc and the bentonite water injection line according to the calculated injection volume and mixing ratio, including pressure, flow rate and injection angle;

[0052] S4.4. Use sensors to monitor the moisture and density of the soil in real time, and apply feedback control logic to adjust the injection amount of water and bentonite.

[0053] Further, the mathematical formula involved in calculating the injection amount of water and bentonite in S4.2 is as follows:

[0054] V material =a×V soil ×t;

[0055] Among them, V material is the total volume of the required materials; a is the mixing ratio; V soil is the volume of soil treated in the corresponding cycle; t is the excavation cycle time;

[0056] The mathematical formulas involved in applying feedback control logic in S4.4 to adjust the injection amount of water and bentonite are as follows:

[0057] V adjusted =V set +k×(V set -V measured );

[0058] Among them, V adjusted is the adjusted injection volume; V set is the set injection volume; V measured is the actual measured injection volume; k is the adjustment factor.

[0059] Furthermore, in S5, the improvement effect of the cutterhead and the slag is evaluated, system maintenance is performed, and the water supply pipeline is checked and cleaned to ensure the continuity and efficiency of the shield tunneling operation, including the following steps:

[0060] S5.1. Determine whether the fluidity, plasticity and stability of the soil meet the excavation requirements, take soil samples from the front of the cutterhead, conduct physical and chemical tests, including moisture content test, compression strength test and rheology test, and analyze the test results;

[0061] S5.2. Check and clean all water supply pipes, and perform pressure test and flow test on the system.

[0062] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0063] 1. In this method of improving soil during excavation in mudstone strata using an earth pressure balance shield, by adding a frequency converter to the original bentonite pump, the operating frequency and output pressure of the pump can be accurately adjusted to achieve accurate injection of soil improvement materials, improve the plasticity and adaptability of the soil, and ensure efficient operation of the shield machine under different stratum conditions.

[0064] 2. By using intelligent water flow dynamic control technology to control the water flow in real time, the amount of water added can be automatically adjusted according to the real-time geological data and the state of the slag during the excavation process, so as to achieve continuous optimization of the slag characteristics and maximize the excavation efficiency, and reduce mechanical failures and downtime caused by improper slag handling.

[0065] 3. The present invention solves the problem of mud cake formation during shield machine excavation in mudstone strata and the problem of insufficient water addition for slag improvement, effectively reduces the thrust of the shield machine, the torque of the cutterhead and the screw machine, reduces tool wear, increases the excavation speed, has low modification difficulty, is economical, practical, convenient, and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0067] Figure 1 The present invention is a flow chart of an embodiment of a method for improving excavation debris in mudstone strata by an earth pressure balance shield. DETAILED DESCRIPTION

[0068] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0069] Example

[0070] like Figure 1 As shown, this embodiment provides a method for improving soil excavation in mudstone strata by an earth pressure balance shield, comprising the following steps:

[0071] S1. Conduct stratigraphic analysis on mudstone formations, select improved materials, and check all technical equipment;

[0072] Formation analysis includes formation property assessment and data analysis;

[0073] The formation property assessment involves geological survey of mudstone formations to assess the physical and chemical properties of mudstone, including hardness, water content, viscosity, and weathering susceptibility. The data analysis involves analyzing the collected formation data to determine the range of variation and geological conditions of the mudstone.

[0074] Improved materials include bentonite slurries, clays, high molecular weight polymers and specially formulated foams;

[0075] The technical equipment includes shield machine operation panel, inverter PLC control circuit, foam box, foam pipeline, foam pump, foam generator, foam pipeline, bentonite soil bin water addition, water spray in front of the cutter disc, foam cutter disc nozzle, water spray on the back of the cutter disc, bentonite water injection line, water tank water injection line, water tank water addition inverter, bentonite water addition inverter, water tank water addition pump, bentonite pump, water tank, and bentonite box.

[0076] S2. Add a frequency converter to the original 15kW bentonite pump. The frequency converter is integrated with the central control system of the shield machine through an intelligent control interface to control the bentonite pump.

[0077] In this embodiment, the control of the bentonite pump is realized by the frequency converter, including the following steps:

[0078] S2.1. Select the inverter of corresponding specifications according to the power and operation requirements of the bentonite pump and test its compatibility;

[0079] S2.2. Install the frequency converter on the control panel of the bentonite pump;

[0080] S2.3, configure the intelligent control interface of the inverter to realize data exchange with the central control system of the shield machine through the CAN communication protocol;

[0081] S2.4. Set the starting frequency, acceleration time and deceleration time of the inverter according to the working requirements of the bentonite pump;

[0082] Among them, the frequency adjustment formula of the frequency converter for the bentonite pump is as follows:

[0083] f=f0+K p ×(SP-PV);

[0084] Where, f is the inverter output frequency; f0 is the reference frequency; K p is the proportional gain; SP is the set point; PV is the process variable;

[0085] Among them, the frequency adjustment formula is used to dynamically adjust the output frequency of the bentonite pump according to the actual operation requirements to achieve accurate control of flow or pressure. The proportional gain K pIt determines the response speed and stability of the control system, which needs to be optimized through actual testing. By adjusting the frequency in real time, it can ensure that the pump output is synchronized with the excavation demand, thereby effectively controlling the shield machine's soil improvement process;

[0086] Among them, the CAN communication protocol is a highly reliable network protocol that is used to provide real-time performance and high anti-interference capabilities in a high-speed data exchange environment. It is suitable for industrial occasions with relatively harsh environments.

[0087] S3, add a water tank, two 15kW piston pumps of the same specification as the bentonite pump, and set up frequency converters, flow sensors and pressure sensors, and use intelligent water flow dynamic control technology to control the water flow in real time;

[0088] In this embodiment, one water tank and two 15kW piston pumps of the same specification as the bentonite pump are added to provide sufficient water reserves and the required high-pressure water flow;

[0089] The water tank added in this embodiment can provide sufficient water reserves to ensure that sufficient water is continuously supplied throughout the excavation process. This is particularly important because in special geological conditions such as mudstone formations, the slag needs an appropriate amount of water to improve its fluidity and plasticity, thereby avoiding cutterhead blockage and conveying system failure. The use of two 15kW piston pumps of the same specification increases the redundancy and reliability of the system. When one pump is maintained or fails, the other can take over to ensure uninterrupted water supply. In addition, the multi-pump system allows for more flexible operation, and the flow and pressure can be adjusted according to actual needs to adapt to different excavation conditions.

[0090] In this embodiment, a frequency converter is provided to adjust the running speed of the pump. By controlling the power frequency of the motor, the frequency converter can accurately adjust the output of the pump to achieve fine control of the flow rate and pressure. Flow and pressure sensors are provided to provide real-time data on the system status. The flow sensor can measure the amount of water passing through the system, while the pressure sensor can monitor the water pressure in the system. Dynamic water flow regulation can be achieved to ensure that the optimal water flow conditions are always maintained during the operation of the shield machine.

[0091] Among them, the intelligent water flow dynamic control technology in this embodiment is realized based on frequency conversion control technology and PID control algorithm, which is used to optimize the water flow and pressure in the slag processing process of the earth pressure balance shield machine and realize the adaptive water resource management function. The intelligent water flow dynamic control technology realizes real-time control of water addition flow, including the following steps:

[0092] S3.1. Define system variables, including real-time flow Q(t), target flow Q set(t), pump inlet pressure and outlet pressure, initialization of PID controller parameters, flow equation parameters, pump characteristic parameters and system resistance parameters;

[0093] S3.2, use flow sensors and pressure sensors to monitor real-time flow, pump inlet and outlet pressures;

[0094] S3.3, calculate the flow error e(t), and use the PID controller to determine the control output u(t) through the proportion, integration and differentiation of the calculated flow error e(t) to adjust the speed of the water pump or the valve opening;

[0095] The mathematical formula involved in calculating the flow error e(t) in this embodiment is as follows:

[0096] e(t)=Q set (t)-Q(t);

[0097] Among them, Q set (t) is the target flow; Q(t) is the real-time flow; e(t) is the difference between the target flow and the real-time flow;

[0098] The specific mathematical formula involved in using the PID controller to determine the control output u(t) by calculating the proportion, integration and differentiation of the flow error is as follows:

[0099]

[0100] Among them, K p is the proportional gain, which is directly multiplied by the error and responds to the immediate deviation; K i is the integral gain; K d is the differential gain; u(t) represents the control output of the PID controller.

[0101] S3.4, adjust the pump speed to match the target flow rate according to the control output u(t), and monitor whether the relationship between the actual flow rate and the system pressure conforms to the theoretical and actual working curves;

[0102] In this embodiment, the relationship between monitoring the actual flow rate and the system pressure involves the relationship between the flow rate Q and the system pressure ΔP difference and the performance of the pump;

[0103] Among them, the mathematical model formula involved in the relationship between flow rate Q and system pressure difference ΔP is as follows:

[0104]

[0105] Among them, C d is the flow coefficient; A is the pipe cross-sectional area; ρ is the water density;

[0106] Among them, the characteristic curve equation involved in the performance of the pump is as follows:

[0107] H=H0-kQ 2 ;

[0108] Where H is the total head generated by the pump; H0 is the maximum head of the pump at zero flow; k is a constant related to the pump characteristics; and Q is the flow rate of the pump.

[0109] S3.5. Use real-time data feedback from flow sensors and pressure sensors to adjust K p , K i , K d , optimize the control effect, consider the influence of system resistance on control, and adjust the total pressure loss ΔP;

[0110] In this embodiment, real-time data feedback from flow sensors and pressure sensors is used to adjust K p Quick response error, adjust K i Eliminate long-term errors and adjust K d Prevent overshoot and system oscillation; the mathematical formula involved in adjusting the total pressure loss ΔP is as follows:

[0111]

[0112] Where ΔP is the total pressure loss; f is the friction factor; L is the pipe length; D is the pipe diameter; v is the flow velocity; K r is the local resistance coefficient, and ρ is the density of the improved medium.

[0113] S4. During the tunneling of the shield machine, the slag is improved in real time through the water spray port in front of the shield machine cutter head and the bentonite water injection line;

[0114] In this embodiment, the slag is improved in real time through the water spray port in front of the shield machine cutter head and the bentonite water injection line to maintain the stability and working conditions of the slag in front of the shield machine cutter head, improve the excavation efficiency and reduce the mechanical failure rate, which includes the following steps:

[0115] S4.1. Determine the specific needs for soil improvement, including increasing the plasticity of the soil, reducing its permeability, or improving its fluidity;

[0116] S4.2. Calculate the mixing ratio and injection volume of water and bentonite;

[0117] The mathematical formulas involved in calculating the injection amount of water and bentonite in this embodiment are as follows:

[0118] V material =a×V soil ×t;

[0119] Among them, V material is the total volume of the required materials; a is the mixing ratio; Vsoil is the volume of soil treated in the corresponding cycle; t is the excavation cycle time;

[0120] S4.3, configure the water spray port and injection line, and set the parameters of the water spray port in front of the cutter disc and the bentonite water injection line according to the calculated injection volume and mixing ratio, including pressure, flow rate and injection angle;

[0121] S4.4, use sensors to monitor the moisture and density of the soil in real time, and apply feedback control logic to adjust the injection amount of water and bentonite;

[0122] The mathematical formulas involved in applying feedback control logic to adjust the injection amount of water and bentonite in this embodiment are as follows:

[0123] V adjusted =V set +k×(V set -V measured );

[0124] Among them, V adjusted is the adjusted injection volume; V set is the set injection volume; V measured is the actual measured injection volume; k is the adjustment factor.

[0125] S5. After each tunneling ring is completed, the improvement effect of the cutterhead and slag is evaluated, system maintenance is carried out, and the water supply pipeline is checked and cleaned.

[0126] In this embodiment, the improvement effect of the cutterhead and the slag is evaluated, the system maintenance is performed, and the water supply pipeline is checked and cleaned to ensure the continuity and efficiency of the shield tunneling operation, including the following steps:

[0127] S5.1. Determine whether the fluidity, plasticity and stability of the soil meet the excavation requirements, take soil samples from the front of the cutterhead, conduct physical and chemical tests, including moisture content test, compression strength test and rheology test, and analyze the test results;

[0128] S5.2. Check and clean all water supply pipes, and perform pressure test and flow test on the system.

[0129] The present invention solves the problem of mud cake formation during shield tunneling in mudstone formations and the problem of insufficient water addition for slag improvement, effectively reduces the thrust of the shield machine, the torque of the cutterhead and screw machine, reduces tool wear, increases the tunneling speed, has low modification difficulty, is economical, practical, convenient, and easy to promote. In addition, by using intelligent water flow dynamic control technology to control the water addition flow in real time, the water addition amount can be automatically adjusted according to the real-time geological data and slag status during the tunneling process, so as to achieve continuous optimization of slag characteristics and maximization of tunneling efficiency, and reduce mechanical failures and downtime caused by improper slag treatment.

[0130] It should be noted that the above description of the disclosed embodiments enables professionals and technicians in the field to implement or use the present application. Various modifications to these embodiments will be apparent to professionals and technicians in the field, and the general principles defined herein can be implemented in other embodiments without departing from the scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

[0131] In the description of the present invention, it should be noted that the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0132] In the description of this document, terms such as "up", "down", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", and "longitudinal" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only used to illustrate the relative positional relationships between the various components or components, and do not particularly limit the specific installation orientations of the various components or components.

[0133] In the description of this document, some terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to the specific circumstances.

[0134] In the description of this document, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0135] The structures, proportions, sizes, etc. drawn in the drawings in this application are only used to match the contents disclosed in this technical briefing book for technical personnel in this field to understand and read, and are not used to limit the restrictive conditions for the implementation of this application. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application.

[0136] The terms used in this document are those common terms currently widely used in the art in consideration of the functions of the present disclosure, but these terms may vary according to the intention of a person of ordinary skill in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in this case, their detailed meanings will be described in the detailed description of the present disclosure. Therefore, the terms used in the document should not be understood as simple names, but rather as an overall description based on the meaning of the terms and the present disclosure.

[0137] Flowcharts or text are used in this document to illustrate the operating steps performed according to the embodiments of the present application. It should be understood that the operating steps in the embodiments of the present application are not necessarily accurately performed in the order of recording. On the contrary, various steps can be processed in reverse order or simultaneously as needed. At the same time, other operations can also be added to these processes, or a certain step or several steps can be removed from these processes.

[0138] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for improving soil excavation in mudstone strata by using an earth pressure balance shield. Features: The following steps are involved: S1. Conduct stratigraphic analysis on mudstone formations and select improved materials; S2. Add a frequency converter to the original bentonite pump. The frequency converter is integrated with the central control system of the shield machine through an intelligent control interface to realize the control of the bentonite pump. S3, add a water tank, two piston pumps of the same specifications as the bentonite pump, and set up frequency converters, flow sensors and pressure sensors at the same time, and use intelligent water flow dynamic control technology to control the water flow in real time; S4. During the tunneling of the shield machine, the slag is improved in real time through the water spray port in front of the shield machine cutter head and the bentonite water injection line; S5. After each tunneling ring is completed, the improvement effect of the cutterhead and slag is evaluated, system maintenance is carried out, and the water supply pipeline is checked and cleaned.

2. The method for improving soil in mudstone strata excavation by an earth pressure balance shield according to claim 1, Features: In S1, formation analysis includes formation property evaluation and data analysis; The formation property assessment includes conducting geological surveys on mudstone formations to assess the physical and chemical properties of mudstone, including hardness, water content, viscosity and weathering susceptibility; the data analysis includes analyzing the collected formation data to determine the variation range and geological conditions of the mudstone; The improved materials include bentonite slurry, clay, high molecular polymer and specially formulated foam.

3. The method for improving soil in mudstone strata excavation by an earth pressure balance shield according to claim 1, Features: In S2, the bentonite pump is controlled by the frequency converter, including the following steps: S2.

1. Select the inverter of corresponding specifications according to the power and operation requirements of the bentonite pump and test its compatibility; S2.

2. Install the frequency converter on the control panel of the bentonite pump; S2.3, configure the intelligent control interface of the inverter to realize data exchange with the central control system of the shield machine through the CAN communication protocol; S2.

4. Set the starting frequency, acceleration time and deceleration time of the inverter according to the working requirements of the bentonite pump; The frequency adjustment formula of the frequency converter for the bentonite pump is as follows: f=f 0 +K p ×(SP-PV); Where, f is the inverter output frequency; f 0 is the reference frequency; K p is the proportional gain; SP is the set point; PV is the process variable.

4. The method for improving soil in mudstone strata excavation by an earth pressure balance shield according to claim 1, Features: The intelligent water flow dynamic control technology is implemented based on frequency conversion control technology and PID control algorithm. The intelligent water flow dynamic control technology realizes real-time control of water addition flow, including the following steps: S3.

1. Define system variables, including real-time flow Q(t), target flow Q set (t), pump inlet pressure and outlet pressure, initialization of PID controller parameters, flow equation parameters, pump characteristic parameters and system resistance parameters; S3.2, use flow sensors and pressure sensors to monitor real-time flow, pump inlet and outlet pressures; S3.3, calculate the flow error e(t), and use the PID controller to determine the control output u(t) through the proportion, integration and differentiation of the calculated flow error; S3.4, adjust the pump speed to match the target flow rate according to the control output u(t), and monitor whether the relationship between the actual flow rate and the system pressure conforms to the theoretical and actual working curves; S3.

5. Use real-time data feedback from flow sensors and pressure sensors to adjust K p , K i , K d , optimize the control effect, consider the influence of system resistance on control, and adjust the total pressure loss ΔP; Among them, K p is the proportional gain, which is directly multiplied by the error and responds to the immediate deviation; K i is the integral gain; K d is the differential gain.

5. The method for improving soil in mudstone strata excavation by an earth pressure balance shield according to claim 4, Features: The mathematical formula involved in calculating the flow error e(t) in S3.3 is as follows: e(t)=Q set (t)-Q(t); Among them, Q set (t) is the target flow; Q(t) is the real-time flow; e(t) is the difference between the target flow and the real-time flow; The specific mathematical formula involved in using the PID controller to determine the control output u(t) by calculating the proportion, integration and differentiation of the flow error is as follows: u(t) represents the control output of the PID controller.

6. The method for improving soil in mudstone strata excavation by an earth pressure balance shield according to claim 4, Features: The relationship between the actual flow rate and the system pressure monitored in S3.4 involves the relationship between the flow rate Q and the system pressure difference ΔP and the performance of the pump; The mathematical model formula involved in the relationship between the flow rate Q and the system pressure difference ΔP is as follows: Among them, C d is the flow coefficient; A is the pipe cross-sectional area; ρ is the water density; The characteristic curve equation involved in the performance of the pump is as follows: H=H 0 -kQ 2 ; Where H is the total head generated by the pump; H 0 is the maximum head of the pump at zero flow; k is a constant related to the pump characteristics; Q is the flow rate of the pump.

7. The method for improving soil in mudstone strata excavation by an earth pressure balance shield according to claim 4, Features: S3.5 uses real-time data feedback from flow sensors and pressure sensors to adjust K p Quick response error, adjust K i Eliminate long-term errors and adjust K d To prevent overshoot and system oscillation, the mathematical formula involved in adjusting the total pressure loss ΔP is as follows: Where ΔP is the total pressure loss; f is the friction factor; L is the pipe length; D is the pipe diameter; v is the flow velocity; K r is the local resistance coefficient, and ρ is the density of the improved medium.

8. The method for improving soil in mudstone strata excavation by an earth pressure balance shield according to claim 1, Features: In S4, the slag is improved in real time through the water spray port in front of the shield machine cutter head and the bentonite water injection line, including the following steps: S4.

1. Determine the specific needs for soil improvement, including increasing the plasticity of the soil, reducing its permeability, or improving its fluidity; S4.

2. Calculate the mixing ratio and injection volume of water and bentonite; S4.3, configure the water spray port and injection line, and set the parameters of the water spray port in front of the cutter disc and the bentonite water injection line according to the calculated injection volume and mixing ratio, including pressure, flow rate and injection angle; S4.

4. Use sensors to monitor the moisture and density of the soil in real time, and apply feedback control logic to adjust the injection amount of water and bentonite.

9. The method for improving soil in mudstone strata excavation by an earth pressure balance shield according to claim 8, Features: The mathematical formulas involved in calculating the injection rates of water and bentonite in S4.2 are as follows: In material =a×V soil ×t; Among them, V material is the total volume of the required materials; a is the mixing ratio; V soil is the volume of soil treated in the corresponding cycle; t is the excavation cycle time; The mathematical formulas involved in applying feedback control logic in S4.4 to adjust the injection amount of water and bentonite are as follows: V adjusted =V set +k×(V set -V measured ); Among them, V adjusted is the adjusted injection volume; V set is the set injection volume; V measured is the actual measured injection volume; k is the adjustment factor.

10. The method for improving soil in mudstone strata excavation by an earth pressure balance shield according to claim 1, Features: In S5, the improvement effect of the cutterhead and the slag is evaluated, the system maintenance is carried out, and the water supply pipeline is inspected and cleaned to ensure the continuity and efficiency of the shield tunneling operation, including the following steps: S5.

1. Determine whether the fluidity, plasticity and stability of the soil meet the excavation requirements, take soil samples from the front of the cutterhead, conduct physical and chemical tests, including moisture content test, compression strength test and rheology test, and analyze the test results; S5.

2. Check and clean all water supply pipes, and perform pressure test and flow test on the system.

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