Soil pressure balance active control method based on internal friction angle of soil

Abstract

The invention discloses a soil pressure balance active control method based on an internal friction angle of soil, which comprises the following steps: measuring the slump and the expansion degree of muck based on a slump test, and further obtaining the internal friction angle of an unimproved soil body; based on the internal friction angle of the unimproved soil body, an active soil pressure coefficient and a passive soil pressure coefficient are obtained; when the active soil pressure coefficient or the passive soil pressure coefficient exceeds a safety threshold value, a target active soil pressure coefficient and a target passive soil pressure coefficient are set; based on the target active soil pressure coefficient and the target passive soil pressure coefficient, reversely calculating a target internal friction angle, and reversely deducing a target slump; and determining the mixing amount of the muck modifier according to the target slump, improving the muck, and carrying out feedback adjustment on the active soil pressure coefficient and the passive soil pressure coefficient of the improved muck until the active soil pressure coefficient and the passive soil pressure coefficient fall into a safety threshold value, so that soil pressure balance is realized. According to the invention, the internal friction angle is associated with the slump, the field calculation of the internal friction angle can be quickly completed, and the precision of earth pressure balance control is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of earth pressure balance control, and particularly relates to an active earth pressure balance control method based on the internal friction angle of soil. Background Technique

[0002] The earth pressure balance shield technology is the core method for ensuring the stability of the excavation face in underground tunnel engineering. Its basic principle is to dynamically adjust the soil pressure in the soil chamber of the shield machine to balance the water and soil pressure of the excavation face stratum, thereby avoiding surface settlement or collapse accidents. During the construction process, the cutterhead of the shield machine rotates to cut the soil in front, and the crushed muck enters the sealed soil chamber through the openings of the cutterhead, and then is discharged through the screw conveyor. By controlling the rotation speed of the screw conveyor or the shield propulsion speed, the accumulated amount of muck in the soil chamber can be dynamically adjusted, and finally the dynamic balance between the soil chamber pressure and the stratum pressure is achieved.

[0003] The reasonable setting of the soil chamber pressure is one of the core control parameters in shield construction. If the soil chamber pressure is too high, although it can maximally inhibit surface settlement, it will cause a significant increase in the cutterhead torque and the thrust of the propulsion cylinders, reduce the shield tunneling efficiency, and at the same time exacerbate equipment wear and energy consumption. On the contrary, if the soil chamber pressure is insufficient, it may cause instability of the excavation face, resulting in the influx of water and soil into the soil chamber or local collapse of the stratum, causing excessive surface settlement or even the risk of collapse. Therefore, the setting of the soil chamber pressure needs to find an optimal solution between safety and economy.

[0004] Currently, the theoretical setting of the soil chamber pressure is mainly based on the theories of active earth pressure, static earth pressure, and passive earth pressure in classical soil mechanics. However, there are multiple technical bottlenecks in the control of the soil chamber pressure in actual engineering:

[0005] Dynamic change of muck properties: The particle composition, water content, and unit weight of the excavated soil fluctuate with the stratum, and the type and dosage of additives will further change the fluidity and density of the muck, making it difficult to stabilize the mechanical parameters of the muck in the soil chamber. Difficult control of the discharged soil volume: The traditional method maintains the soil chamber pressure through the balance principle of "discharged soil volume ≈ excavated volume", but due to the real-time change of the muck unit weight and the fluctuation of the soil discharge efficiency of the screw conveyor, relying solely on the management of the discharged soil volume is likely to cause pressure out of control. Dependence on experience and disconnection from theory: Although the earth pressure theory provides a framework for pressure setting, actual construction still heavily relies on engineering experience.

[0006] To improve the accuracy of soil chamber pressure control, some technologies attempt to introduce pore water pressure monitoring or optimize the cutterhead torque-thrust ratio algorithm. However, these methods still have obvious defects: The pore water pressure or torque data can only indirectly reflect the soil state, and there is a delay in signal transmission and processing, making it difficult to respond promptly to sudden changes in the stratum. Therefore, the existing improvement schemes essentially still belong to the empirical correction of "adjusting fluidity with fluidity parameters" and fail to establish a direct relationship between the soil mechanical parameters and the soil chamber pressure.

[0007] In addition, the existing earth pressure balance control system still has the following technical bottlenecks in terms of predictability and accuracy:

[0008] Lack of real-time calculation of the internal friction angle: Traditional methods cannot obtain the internal friction angle of the improved soil mass in real time through the fluidity parameters of the muck, resulting in the disconnection between the set earth pressure in the soil chamber and the actual shear strength of the formation. Existing technologies rely on shutdown sampling and laboratory tests, which take ≥ 2 hours, and the earth pressure balance threshold during construction can only be estimated empirically, with too large an error.

[0009] Lags in formation response: It is impossible to predict in advance the attenuation trend of the internal friction angle with the tunneling distance. 60% of the pressure out-of-control accidents occur 15 - 30 minutes after the sudden change of the formation interface, and passive adjustment leads to excessive surface settlement.

[0010] In view of the above problems, there is an urgent need to propose an active earth pressure balance control method based on the internal friction angle of soil. Summary of the Invention

[0011] To solve the above technical problems, the present invention proposes an active earth pressure balance control method based on the internal friction angle of soil to solve the problems existing in the above-mentioned prior art.

[0012] To achieve the above object, the present invention provides an active earth pressure balance control method based on the internal friction angle of soil, including the following steps:

[0013] Based on the slump test, measure the slump and spread of the muck, and obtain the internal friction angle of the unimproved soil mass through a pre-established slump-internal friction angle correlation model;

[0014] Based on the internal friction angle of the unimproved soil mass, obtain the active earth pressure coefficient and the passive earth pressure coefficient through the Rankine earth pressure theory;

[0015] When the active earth pressure coefficient or the passive earth pressure coefficient exceeds the safety threshold, set the target active earth pressure coefficient and the target passive earth pressure coefficient;

[0016] Based on the target active earth pressure coefficient and the target passive earth pressure coefficient, inversely calculate the target internal friction angle, and inversely deduce the target slump through the slump-internal friction angle correlation model;

[0017] Determine the dosage of the muck conditioner through the target slump and implement muck improvement, and perform feedback adjustment on the active earth pressure coefficient and the passive earth pressure coefficient of the improved muck until they fall within the safety threshold to achieve earth pressure balance.

[0018] Optionally, the formula of the slump-internal friction angle correlation model is as follows:

[0019]

[0020] Wherein, is the internal friction angle, Hcylinder is the height of the slump cone, S v is the slump, S f is the spread.

[0021] Optionally, the process of setting the target active earth pressure coefficient and the target passive earth pressure coefficient includes:

[0022] Based on the formation characteristics and equipment parameters, select the optimal values of the active earth pressure coefficient and the passive earth pressure coefficient as the target values, and at the same time ensure that the optimal solution is obtained between the equipment load and the formation safety for the shield soil chamber pressure.

[0023] Optionally, the calculation formula of the shield soil chamber pressure is as follows:

[0024]

[0025] Wherein, P target is the shield soil chamber pressure, γ is the effective unit weight of the soil after muck improvement, h is the equivalent action height of the soil in front of the cutterhead of the shield machine, K a is the active earth pressure coefficient, K p is the passive earth pressure coefficient.

[0026] Optionally, based on the target active earth pressure coefficient and the target passive earth pressure coefficient, the formula for inversely calculating the target internal friction angle is as follows:

[0027]

[0028] Wherein, φ1 is the target internal friction angle.

[0029] The present invention also provides an earth pressure balance active control system based on the internal friction angle of soil for implementing the above method, including: a slump test module, an internal friction angle calculation module, an earth pressure coefficient calculation module, and a regulation module;

[0030] The slump test module is used to measure the slump and spread of the muck based on the slump test;

[0031] The internal friction angle calculation module is used to obtain the internal friction angle of the unimproved soil through a pre-established slump-internal friction angle correlation model;

[0032] The earth pressure coefficient calculation module is used to obtain the active earth pressure coefficient and the passive earth pressure coefficient based on the internal friction angle of the unimproved soil through the Rankine earth pressure theory;

[0033] The control module is used to set the target active earth pressure coefficient and the target passive earth pressure coefficient when the active earth pressure coefficient or the passive earth pressure coefficient exceeds the safety threshold, and based on the target active earth pressure coefficient and the target passive earth pressure coefficient, inversely calculate the target internal friction angle and the target slump, determine the admixture dosage of the muck conditioner through the target slump and implement muck improvement.

[0034] Optionally, the control module includes a data feedback unit and an optimization unit;

[0035] The data feedback unit is used to monitor the active earth pressure coefficient and the passive earth pressure coefficient of the improved muck in real time;

[0036] The optimization unit is used to compare the active earth pressure coefficient and the passive earth pressure coefficient of the improved muck with the preset safety threshold. If the deviation exceeds the limit, the admixture dosage of the muck conditioner is dynamically adjusted until the active earth pressure coefficient and the passive earth pressure coefficient of the improved muck fall within the safety threshold to achieve earth pressure balance.

[0037] The present invention also provides a computer device, including a memory, a processor and a computer program stored on the memory, and the processor executes the computer program to implement the steps of the method.

[0038] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and characterized in that the computer program realizes the steps of the method when being executed by a processor.

[0039] The present invention also provides a computer program product, including a computer program, and characterized in that the computer program realizes the steps of the method when being executed by a processor.

[0040] Compared with the prior art, the present invention has the following advantages and technical effects:

[0041] The present invention realizes the real-time accurate measurement and dynamic regulation of the internal friction angle: The traditional method relies on laboratory triaxial tests or direct shear tests to measure the internal friction angle, which takes several hours and cannot reflect the dynamic changes of the muck improvement effect during construction. However, the present invention relates the internal friction angle to the slump, and through the internal friction angle formula, the on-site calculation of the internal friction angle can be quickly completed, greatly improving the accuracy of earth pressure balance control and well controlling the error.

[0042] The present invention seamlessly connects muck improvement, parameter testing and pressure regulation to form a technical closed loop of "measurement → calculation → improvement → regulation". Through the collaborative application of a standardized slump tester and conventional geological parameters, the rapid calculation of the balance pressure can be realized without introducing complex equipment, and it has forward predictability. Description of the Drawings

[0043] The accompanying drawings, which form a part of this application, are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0044] Figure 1 It is the earth pressure balance control flow chart of the embodiment of the present invention;

[0045] Figure 2 It is the slump test diagram of the embodiment of the present invention;

[0046] Figure 3 It is the mapping diagram of slump, internal friction angle and earth pressure coefficient of the embodiment of the present invention. Detailed implementation manners

[0047] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will refer to the accompanying drawings and combine the embodiments to detail this application.

[0048] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0049] Embodiment 1

[0050] In the earth pressure balance shield construction, accurately controlling the earth pressure on the excavation face is the core element to ensure the safety and efficiency of the project. However, the stability of the earth pressure directly depends on the mechanical parameters of the soil mass after the muck improvement in front of the shield machine, especially the internal friction angle. The internal friction angle is a key index reflecting the shear strength of the soil mass, and its value directly affects the resistance of the soil mass to the cutterhead of the shield machine and the distribution of the soil chamber pressure. In traditional methods, the determination of the internal friction angle relies on complex triaxial tests or direct shear tests, which are not only time-consuming and laborious, but also unable to realize the real-time monitoring of the improved soil mass during the construction process. This technical bottleneck makes it difficult to improve the predictability and control accuracy of construction parameters, and seriously restricts the reliability and adaptability of shield construction under complex stratum conditions.

[0051] To solve the above problems, as Figure 1 shown, this embodiment provides an earth pressure balance active control method based on the internal friction angle of soil, including the following steps:

[0052] Based on the slump test, determine the slump and spread of the muck, and obtain the internal friction angle of the unimproved soil mass through a pre-established slump-internal friction angle correlation model;

[0053] Based on the internal friction angle of the unimproved soil mass, obtain the active earth pressure coefficient and the passive earth pressure coefficient through the Rankine earth pressure theory;

[0054] When the active earth pressure coefficient or the passive earth pressure coefficient exceeds the safety threshold, set the target active earth pressure coefficient and the target passive earth pressure coefficient;

[0055] Based on the target active earth pressure coefficient and the target passive earth pressure coefficient, inversely calculate the target internal friction angle, and inversely deduce the target slump through the slump-internal friction angle correlation model;

[0056] Determine the dosage of the muck conditioner through the target slump and implement muck improvement, and perform feedback adjustment on the active earth pressure coefficient and the passive earth pressure coefficient of the improved muck until it falls within the safety threshold to achieve earth pressure balance.

[0057] Implementable, this method analyzes the fluidity characteristics of the improved muck and establishes a mathematical relationship model between the slump, the spread, and the internal friction angle, thereby breaking through the limitations of traditional measurement methods. Its core principle lies in that after the muck is improved, the interaction and fluidity between soil particles change significantly, and the slump and the spread, as intuitive parameters representing fluidity, can indirectly reflect the change law of the internal friction characteristics of the soil mass.

[0058] As a specific implementation method, first conduct a slump test. The slump test reflects the plastic deformation ability of the soil mass under its own weight by measuring the free slump height of the muck in the slump cone; by recording the maximum horizontal diffusion diameter after the muck slumps, it characterizes the shear thinning effect when the soil mass flows. Based on the above test data, this embodiment deduces the calculation formula for the internal friction angle:

[0059]

[0060] where φ is the internal friction angle, H_cone is the height of the slump cone, S v is the slump, S f is the spread, that is, the maximum horizontal diffusion diameter after slumping. The specific experiment is as Figure 2 shown.

[0061] This formula converts the soil mass fluidity parameter into a numerical solution of the internal friction angle by quantifying the ratio of the slump to the spread. Among them, the numerator term 2(H 筒 -S v ) reflects the plastic deformation resistance of the soil mass in the vertical direction, while the denominator term S f corresponds to the flow ductility in the horizontal direction. The larger the ratio of the two, the more significant the frictional force between soil particles, and the internal friction angle increases accordingly.

[0062] The core of achieving earth pressure balance during shield tunneling lies in precisely controlling the acting pressure of the shield machine on the front soil mass to make it equal to the critical stability pressure of the soil. This critical pressure is determined by the dynamic balance relationship between the active earth pressure and the passive earth pressure of the soil. The active earth pressure is the minimum lateral pressure of the soil on the supporting structure in the unstable state, while the passive earth pressure is the maximum lateral resistance generated when the soil is compressed. Both are directly controlled by the numerical characteristics of the internal friction angle φ. The difference between the two directly determines the critical pressure value for maintaining the stability of the excavation face.

[0063] Based on the Rankine earth pressure theory, the active earth pressure coefficient K of the soil formed during the shield propulsion process a and the passive earth pressure coefficient K p can be expressed as functions of the internal friction angle:

[0064]

[0065] The active earth pressure coefficient K a : It reflects that the frictional resistance between particles during shear failure of the soil decreases, resulting in a reduction in lateral pressure. When the shield machine advances and causes a small displacement of the front soil mass, the shear action between soil particles weakens. At this time, the thrust generated by the soil on the shield machine is:

[0066] P a =γh·K a ,

[0067] In the formula, the larger the internal friction angle, the smaller the value of K a , indicating that the shear strength of the soil is higher. This characteristic is crucial for the design of the cutter head thrust of the shield machine. One is the optimization of the cutter head torque. Soils with a high φ value (such as dense sand layers) require a higher cutter head torque to overcome the soil shear resistance, and the decrease in K a means a reduction in the active earth pressure. At this time, the set value of the soil chamber pressure needs to be appropriately reduced to avoid overloading the cutter head. The second is the matching of the propulsion speed. In strata with a low K a value (such as soft clay), the active earth pressure is small, and the shield machine can appropriately increase the propulsion speed, but the discharge rate of the screw conveyor needs to be adjusted synchronously to prevent the sudden drop of the soil chamber pressure from causing the instability of the excavation face.

[0068] The passive earth pressure coefficient K p : It characterizes that the frictional force between particles is fully stimulated when the soil is externally compressed, and the lateral resistance is significantly increased. When the shield machine compresses the soil to the ultimate dense state, the frictional resistance between soil particles reaches the peak value. At this time, the resistance generated by the soil is:

[0069] P p =γh·K p ,

[0070] The increase in the internal friction angle φ significantly increases K pThe higher the value, the stronger the ability of the soil mass to resist deformation, which directly determines the construction strategy of the shield machine in dense soil layers. One is the setting of the upper limit of the soil chamber pressure. In sandy gravel or hard clay strata, the P corresponding to the high K value becomes the upper limit reference for setting the soil chamber pressure. If the actual pressure exceeds this value, it may cause a sharp increase in the propulsion resistance of the cutterhead and even lead to equipment jamming. The second is the response to sudden formation changes. When the formation suddenly changes from soft soil to hard rock, the sharp increase in the φ value causes a sharp increase in K, and it is necessary to dynamically reduce the propulsion speed and increase the injection amount of bentonite to relieve the instantaneous impact of the soil mass on the cutterhead. p value corresponds to P p to become the upper limit reference for setting the soil chamber pressure. If the actual pressure exceeds this value, it may cause a sharp increase in the propulsion resistance of the cutterhead and even lead to equipment jamming. The second is the response to sudden formation changes. When the formation suddenly changes from soft soil to hard rock, the sharp increase in the φ value causes a sharp increase in K p and it is necessary to dynamically reduce the propulsion speed and increase the injection amount of bentonite to relieve the instantaneous impact of the soil mass on the cutterhead.

[0071] γ: Effective unit weight of the soil mass after muck improvement (kN / m 3 );

[0072] h: Equivalent acting height of the soil mass in front of the shield cutterhead (m), usually taking the weighted value of the overburden thickness and the shield diameter;

[0073] K a , K p : Active and passive earth pressure coefficients calculated based on the measured internal friction angle φ.

[0074] To achieve the stability of the excavation face, the shield soil chamber pressure P target needs to be between P a and P p . According to engineering practice experience, the optimal balance pressure usually takes the arithmetic mean of the two, that is:

[0075]

[0076] The balance pressure P target is essentially the weighted average of the active and passive earth pressures. The purpose of using the arithmetic mean is to avoid pressure fluctuations under extreme working conditions and ensure the balance of the excavation face stability and the shield propulsion efficiency. The γh term in the formula represents the vertical stress generated by the self-weight of the soil mass, and the product of it and the earth pressure coefficient converts the vertical stress into the lateral pressure component.

[0077] In the traditional construction process, the setting of the balance pressure P target often depends on the empirical formula or the internal friction angle φ0 of the unimproved soil mass provided by the geological exploration report. Geological exploration data are usually based on laboratory tests of the original formation, such as triaxial tests or direct shear tests, which reflect the shear resistance characteristics of the soil mass without injecting modifiers. In actual construction, modifiers such as bentonite and foam added to optimize the muck fluidity will significantly change the interaction between soil particles. For example, the bentonite mud film wraps the soil particles to reduce the frictional resistance, and the foam reduces the shear strength through lubrication. This improvement effect makes the internal friction angle of the muck may be reduced by 30% - 50% compared with the original soil mass, resulting in K calculated based on φ0 a, K p and P target seriously deviate from the actual working conditions, making the values of K a and K p unable to meet the stability requirements of earth pressure balance. For example, in sandy strata, the φ0 of the unimproved soil is relatively high, and the calculated value of K a is on the low side, and the value of K p is on the high side. If the chamber pressure is set directly according to this, it will lead to too high a pressure threshold, resulting in a sharp increase in cutter head torque and a decrease in propulsion efficiency; conversely, in cohesive strata, the φ0 of the unimproved soil is relatively low, and the theoretical pressure threshold may be lower than the actual demand, causing a risk of excavation face instability.

[0078] Therefore, this embodiment proposes a reverse control logic based on the target balance pressure, and the specific steps are as follows:

[0079] (1) Target parameter setting:

[0080] Compare the calculated values of K a and K p with the safety valve value. When the measured value exceeds the engineering safety threshold, it is determined that the unimproved soil cannot meet the excavation face stability requirements, and muck improvement is required.

[0081] According to the engineering safety specifications and formation characteristics, preset a reasonable range of values for K a and K p : According to the formation characteristics and equipment parameters, select the optimal values of K a and K p to ensure that the balance pressure P target obtains the optimal solution between equipment load-bearing and formation safety.

[0082] (2) Inversion calculation of internal friction angle:

[0083] Based on the preset target values of K a and K p , inversely calculate the target internal friction angle φ1 through the Rankine earth pressure formula:

[0084]

[0085] Through double-formula cross-validation, ensure the physical rationality of φ1 (such as φ1 = 20° - 40°) to avoid calculation failure caused by theoretical contradictions.

[0086] (3) Derivation of the target slump value:

[0087] Substitute φ1 into the slump correlation formula Combined with the allowable spread range of the project, inversely deduce the target slump

[0088] For example, if φ1 = 25°, Sf = 450 mm, then S v ≈ 180 mm, indicating that the slump needs to be controlled in the range of 180 ± 20 mm through muck improvement.

[0089] (4) Dynamic regulation of bentonite dosage:

[0090] Based on the target S v value, calculate the required bentonite injection volume Q through historical test data or empirical formulas to ensure that the fluidity of the muck meets the standard, thereby achieving the active regulation of earth pressure balance.

[0091] (5) Closed-loop verification and optimization:

[0092] Real-time monitor the S v and S f of the improved muck, recalculate φ1, K a , K p and P target , and compare with the preset target values. If the standard is met, the shield can be advanced normally; if it is abnormal, it will be fed back to the bentonite dosage module for fine-tuning until the parameters converge within the theoretical range, forming a stable earth pressure balance state.

[0093] Through the above reverse regulation logic, this embodiment realizes the closed-loop control from the target mechanical parameters to the construction operation, breaks through the limitations of the traditional method relying on the parameters of unimproved soil, and provides a precise and adaptive pressure balance solution for shield construction in complex strata.

[0094] This embodiment combines a large number of indoor test and engineering measured data, systematically analyzes the correlation between slump, spread, and internal friction angle, active earth pressure and passive earth pressure under different improvement ratios, and the results are shown in Table 1 and Figure 3 as follows:

[0095] Table 1

[0096]

[0097] On the other hand, based on the same inventive concept as the above embodiment, this embodiment also provides an active earth pressure balance control system based on the internal friction angle of soil. The active earth pressure balance control system and the active earth pressure balance control method provided by the above embodiment can be mutually referred to in terms of effects. The system includes: a slump test module, an internal friction angle calculation module, an earth pressure coefficient calculation module, and a regulation module;

[0098] The slump test module is used to measure the slump and spread of the muck based on the slump test;

[0099] The internal friction angle calculation module is used to obtain the internal friction angle of the unimproved soil through a pre-established slump-internal friction angle correlation model;

[0100] The earth pressure coefficient calculation module is used to obtain the active earth pressure coefficient and the passive earth pressure coefficient based on the internal friction angle of the unimproved soil through the Rankine earth pressure theory;

[0101] The regulation module is used to set the target active earth pressure coefficient and the target passive earth pressure coefficient when the active earth pressure coefficient or the passive earth pressure coefficient exceeds the safety threshold. Based on the target active earth pressure coefficient and the target passive earth pressure coefficient, the target internal friction angle and the target slump are inversely calculated, and the admixture amount of the muck conditioner is determined through the target slump and muck improvement is implemented.

[0102] Implementably, the regulation module includes a data feedback unit and an optimization unit;

[0103] The data feedback unit is used to monitor the active earth pressure coefficient and the passive earth pressure coefficient of the improved muck in real time;

[0104] The optimization unit is used to compare the active earth pressure coefficient and the passive earth pressure coefficient of the improved muck with the preset safety threshold. If the deviation exceeds the limit, the admixture amount of the muck conditioner is dynamically adjusted until the active earth pressure coefficient and the passive earth pressure coefficient of the improved muck fall within the safety threshold to achieve earth pressure balance.

[0105] Embodiment II

[0106] This embodiment also provides a computer device, including a memory, a processor, and a computer program stored on the memory. The processor executes the computer program to implement the steps of the method.

[0107] Embodiment III

[0108] This embodiment also provides a computer-readable storage medium, on which a computer program is stored. It is characterized in that when the computer program is executed by a processor, the steps of the method are implemented.

[0109] Embodiment IV

[0110] This embodiment also provides a computer program product, including a computer program. It is characterized in that when the computer program is executed by a processor, the steps of the method are implemented.

[0111] The above is only a preferred specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An active control method for earth pressure balance based on the internal friction angle of soil, characterized in that: The following steps are involved: The slump and expansion of the soil were measured based on the slump test, and the internal friction angle of the unimproved soil was obtained through the pre-established slump-internal friction angle correlation model; Based on the internal friction angle of the unimproved soil, the active earth pressure coefficient and the passive earth pressure coefficient are obtained by using the Rankine earth pressure theory; When the active earth pressure coefficient or the passive earth pressure coefficient exceeds the safety threshold, the target active earth pressure coefficient and the target passive earth pressure coefficient are set; Based on the target active earth pressure coefficient and the target passive earth pressure coefficient, the target internal friction angle is reversely solved, and the target slump is reversely deduced through the slump-internal friction angle correlation model; The dosage of soil conditioner is determined by the target slump and soil improvement is implemented. The active earth pressure coefficient and passive earth pressure coefficient of the improved soil are feedback-adjusted until they fall within the safety threshold and soil pressure balance is achieved.

2. The method according to claim 1, characterized in that The formula of the slump-internal friction angle correlation model is as follows: Where φ is the internal friction angle, H is the height of the slump cone, S v is the slump, S f For expansion.

3. The method according to claim 1, characterized in that The process of setting the target active earth pressure coefficient and the target passive earth pressure coefficient includes: Based on the formation characteristics and equipment parameters, the optimal values ​​of the active earth pressure coefficient and the passive earth pressure coefficient are selected as the target values, while ensuring that the shield soil bin pressure achieves the optimal solution between equipment bearing and formation safety.

4. The method according to claim 3, characterized in that: The calculation formula of the shield soil bin pressure is as follows: Among them, P target is the shield soil bin pressure, γ is the effective weight of the soil after the slag is improved, h is the equivalent height of the soil in front of the shield machine cutter head, K a is the active earth pressure coefficient, K p is the passive earth pressure coefficient.

5. The method according to claim 4, characterized in that Based on the target active earth pressure coefficient and the target passive earth pressure coefficient, the formula for inversely solving the target internal friction angle is as follows: in, is the target internal friction angle.

6. An active earth pressure balance control system based on the internal friction angle of soil, characterized in that: Used to implement the method described in any one of claims 1 to 5, comprising: a slump test module, an internal friction angle calculation module, an earth pressure coefficient solution module and a control module; The slump test module is used to measure the slump and expansion of the slag based on the slump test; The internal friction angle calculation module is used to obtain the internal friction angle of unimproved soil through a pre-established slump-internal friction angle correlation model; The earth pressure coefficient calculation module is used to obtain the active earth pressure coefficient and the passive earth pressure coefficient through the Rankine earth pressure theory based on the internal friction angle of the unimproved soil; The control module is used to set the target active earth pressure coefficient and the target passive earth pressure coefficient when the active earth pressure coefficient or the passive earth pressure coefficient exceeds the safety threshold, and based on the target active earth pressure coefficient and the target passive earth pressure coefficient, reversely solve the target internal friction angle and the target slump, determine the amount of slag improver through the target slump and implement slag improvement.

7. The system according to claim 6, characterized in that The control module includes a data feedback unit and an optimization unit; The data feedback unit is used to monitor the active earth pressure coefficient and the passive earth pressure coefficient of the improved slag in real time; The optimization unit is used to compare the active earth pressure coefficient and the passive earth pressure coefficient of the improved slag with a preset safety threshold. If the deviation exceeds the limit, the amount of the slag improver is dynamically adjusted until the active earth pressure coefficient and the passive earth pressure coefficient of the improved slag fall within the safety threshold to achieve earth pressure balance.

8. A computer device comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 5.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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