Large-diameter slurry shield tail seal grease injection control system for high-pressure water layer

Abstract

This invention relates to the field of tunnel construction equipment technology, and discloses a sealing grease injection control system for ultra-large diameter slurry shield tunnels in high-pressure water layers. The system includes a central processing module, an acquisition module, an attitude detection module, and an injection module. The central processing module calculates the real-time radial clearance of the injection holes based on the mechanical geometry, constructs a rheological response benchmark model to calculate the theoretical stress relaxation time constant, and controls the injection module to perform pulsed grease injection. During the static observation phase after operation stops, it acquires the transient pressure decay sequence and fits it to extract the measured stress relaxation time constant. The central processing module calculates the ratio of the measured value to the theoretical value to obtain the relaxation coupling index. Based on the relaxation coupling index, it identifies the physical state of the sealing cavity and generates high-pressure replacement, dense filling, or standard maintenance commands to adjust the injection parameters. This invention decouples the sealing state through physical response characteristics, solves the problem of grease injection control lag under complex working conditions, and improves the safety of shield tunneling construction.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction equipment technology, specifically to a control system for injecting sealing grease into the tail of a large-diameter slurry shield tunnel in a high-pressure water layer. Background Technology

[0002] When ultra-large diameter slurry shield tunneling machines traverse geological environments with high pressure water layers such as rivers, lakes, and seas, the reliability of the shield tail sealing system is directly related to construction safety. The shield tail sealing system consists of multiple wire brushes and shield tail sealing grease filled between the wire brushes. By injecting grease into the sealing cavity, a pressure barrier is established to resist the intrusion of external high-pressure water and soil.

[0003] Existing shield tail sealing grease injection control methods rely on pressure threshold control or stroke volume control. The control system sets a fixed pressure range or grease injection volume per unit tunneling distance. When the detected pressure is lower than the set lower limit or the grease injection volume does not reach the preset value, the grease injection pump is activated. However, in actual engineering, the tunneling posture of the tunnel boring machine is frequently adjusted, resulting in uneven distribution of the shield tail gap in the circumferential direction. When the shield tail gap changes, the pressure response characteristics in the sealing cavity will change accordingly. The fixed pressure threshold cannot adapt to the dynamically changing geometric boundary conditions.

[0004] Especially in high-confined aquifer environments, where external water and soil pressures are high, when a seal fails and water intrusion occurs, the pressure sensor readings within the sealing cavity remain at a high level. This reading actually reflects the pressure of the intruding water, not the effective supporting pressure of the sealing grease. Existing control logic struggles to distinguish whether the high pressure within the sealing cavity originates from the dense filling of the grease or the conduction of external high-pressure water, easily leading to misjudgments of pressure reaching the target, causing grease injection delays, and ultimately triggering shield tail leakage accidents. Furthermore, existing technologies lack dynamic analysis of the rheological properties of the sealing grease under pressure, focusing only on instantaneous pressure values ​​while ignoring the physical state information implied by the pressure decay rate after pumping stops, making early identification of hidden defects such as air pocket cavities or grease loss difficult. Therefore, this invention proposes a sealing grease injection control system for ultra-large diameter slurry shield tunnels in high-confined aquifer environments to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in high-pressure water layers. This system solves the problem that existing technologies struggle to accurately identify the physical state of the tail sealing cavity in complex hydrogeological environments, leading to delayed or failed grease injection control.

[0006] To achieve the above objectives, the present invention provides a sealing grease injection control system for the tail of a high-pressure water layer ultra-large diameter slurry shield tunnel, including a central processing module, an acquisition module, an attitude detection module, and an injection module. The central processing module is connected to the other modules and configured to execute bidirectional closed-loop control logic.

[0007] The central processing module first constructs a rheological response benchmark model to obtain theoretical reference. Specifically, based on the mechanical geometric state data transmitted by the attitude detection module, the central processing module calculates the real-time radial clearance value at the grease injection hole, and combines the pre-stored rheological parameters of the sealing grease and the elastic modulus characteristics of the wire brush to calculate the theoretical stress relaxation time constant under the current working condition.

[0008] The system acquires measured response data through pulsed grease injection. The central processing module sends an action command to the injection module, controlling it to stop operating and enter a silent observation phase after the grease injection volume reaches a preset value. The central processing module acquires the transient pressure decay sequence collected by the acquisition module during the silent observation phase and extracts the measured stress relaxation time constant through a fitting algorithm.

[0009] The central processing module uses the ratio of the measured stress relaxation time constant to the theoretical stress relaxation time constant to obtain the relaxation coupling index. The relaxation coupling index is used to characterize the physical state of the sealed cavity. The central processing module generates control commands based on the numerical range of the relaxation coupling index to adjust the operating parameters of the injection module.

[0010] Regarding the acquisition of the real-time radial clearance value, the central processing module performs the following calculation steps: based on the stroke data of the articulated cylinder, the horizontal and vertical eccentricities of the shield tail center relative to the segment ring center are calculated through coordinate transformation; external water and soil pressure data are acquired and the shield shell compression deformation compensation is calculated based on the shield shell radial compressive stiffness coefficient; finally, the difference between the shield tail radius and the outer diameter of the segment is taken as the nominal clearance, the eccentricity projection component is superimposed and the deformation compensation is subtracted to obtain the real-time radial clearance value.

[0011] Regarding the calculation of the theoretical stress relaxation time constant, the central processing module determines the compression ratio of the wire brush based on the real-time radial gap value, linearly superimposes the bulk modulus of the sealing grease with the nonlinear stiffness contribution value under the compression ratio, and calculates the equivalent bulk modulus of the sealing cavity; simultaneously, it uses the Arrhenius equation of state to calculate the zero-shear dynamic viscosity of the sealing grease based on real-time temperature data, and divides the zero-shear dynamic viscosity by the equivalent bulk modulus to obtain the theoretical stress relaxation time constant.

[0012] Regarding the extraction of the measured stress relaxation time constant, the central processing module extracts the pressure sampling sequence after a preset delay from the stop time of the grease pump as the effective data window; constructs a pressure decay mathematical model including steady-state residual pressure, pressure decay amplitude, and exponential decay term; performs a logarithmic linearization transformation on the model, and uses the least squares method to regress and analyze the parameters characterizing the decay rate of transient components with time, taking their reciprocals as the result.

[0013] In addition, the central processing module executes flow resistance monitoring logic during pulsed grease injection. The system determines the pipeline status by calculating the pressure rise slope: if the slope exceeds the rigid blockage threshold, it is determined to be a physical blockage; if it is below the leakage threshold, it is determined to be a pipeline disconnection or a through-leak; only when the slope is between the two is the operating condition confirmed to be normal, allowing the subsequent parameter extraction process to be triggered.

[0014] Based on the relaxation coupling index, the system executes the following hierarchical control strategy: If the relaxation coupling index is less than the water intrusion threshold, water intrusion is detected, and the system enters high-pressure replacement mode. The central processing module uses the replacement gain coefficient to amplify the single grease injection volume and sets the upper limit of the grease injection pressure according to the external water and soil pressure, instructing the injection module to continuously pump sealing grease until the index recovers. If the relaxation coupling index is greater than the airbag cavity detection threshold, airbag cavities or sealing brush elastic failure are detected, and the system enters dense filling mode. The central processing module shortens the time interval between two adjacent pulse grease injections and reduces the instantaneous injection flow rate to maintain laminar flow and discharge gas. If the relaxation coupling index is within the above thresholds, the sealing status is determined to be normal, and the system enters standard maintenance mode. Based on the principle of volume conservation, the central processing module calculates the theoretical grease injection flow rate according to the tunnel boring machine's advance speed and shield tail geometric parameters, and dynamically adjusts the action frequency to maintain volume balance.

[0015] The acquisition module includes several pressure sensors distributed along the circumference of the shield tail, used to acquire transient waveforms after pumping stops; the injection module includes a grease pump and a control valve connected in series, the control valve being configured to cut off the fluid channel and isolate the pumping pipeline from the sealed chamber when pumping stops.

[0016] This invention provides a sealing grease injection control system for the tail of an ultra-large diameter slurry shield tunneling machine operating in high-confined aquifers. It offers the following advantages: 1. This invention establishes a dynamic theoretical stress relaxation time constant as an evaluation benchmark by constructing a rheological response benchmark model and combining it with real-time attitude calculation. The system compares the measured stress relaxation time constant extracted during the silent observation phase with the theoretical benchmark to calculate the relaxation coupling index. This can distinguish the medium properties (such as grease, water, or gas) in the sealed cavity, solving the problem of misjudgment caused by difficulty in accurately identifying the sealing state under variable gap conditions, and improving the accuracy of judging the integrity of the shield tail seal.

[0017] 2. Based on the numerical range of the relaxation coupling index, this invention specifically designs three operating modes: high-pressure replacement, dense filling, and standard maintenance. When water intrusion is detected, the system achieves forced replacement by increasing the grease injection volume and setting an upper pressure limit. When air bladder cavities are detected, the system maintains laminar flow by increasing the grease injection frequency and reducing the flow rate to expel gas. This avoids the blindness of traditional single grease injection modes in dealing with complex working conditions and ensures that the shield tail sealing structure can be quickly restored to an effective working state under different geological risks.

[0018] 3. This invention integrates flow resistance monitoring logic into the grease injection control, and uses the pressure rise slope to realize real-time diagnosis of the physical state of the grease injection pipeline. With the control valve set in series, the fluid channel is physically cut off when the grease injection pump stops running. On the one hand, the system can promptly identify abnormal conditions such as pipeline blockage or disconnection to prevent equipment damage or grease leakage. On the other hand, it can isolate the interference of residual pressure in the pumping pipeline on the pressure decay process of the sealed chamber, ensuring the authenticity and reliability of the basic data used for condition analysis. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the system architecture of the present invention; Figure 2 This is a schematic diagram of the overall process of the method of the present invention; Figure 3 This is a schematic diagram comparing the transient pressure relaxation characteristics under different sealing media according to the present invention; Figure 4 This is a schematic diagram of the time-varying curve and state switching of the relaxation coupling index throughout the entire process of the present invention; Figure 5 This diagram illustrates a comparison of the field application effects of the conventional method and the method of the present invention.

[0020] Legend 100. Central processing module; 200. Acquisition module; 300. Attitude detection module; 400. Injection module; 201. Pressure sensor; 301. Connecting sensor; 302. Propulsion sensor; 401. Grease pump; 402. Control valve. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1The present invention provides a sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in a high-pressure aquifer, including a central processing module 100, a data acquisition module 200, an attitude detection module 300, and an injection module 400.

[0023] The central processing module 100 serves as the core for computation and control, configured to perform logical operations and floating-point calculations. The central processing module 100 adopts an industrial programmable logic controller or an industrial computer. The central processing module 100 is connected to a storage unit, which pre-stores a table of rheological parameters of sealing grease, a curve of elastic modulus characteristics of wire brush, and geometric parameters of the shield tail structure.

[0024] The acquisition module 200 is used to acquire fluid pressure signals. The acquisition module 200 includes several pressure sensors 201. The pressure sensors 201 are distributed along the circumference of the shield tail, with one pressure sensor 201 installed for each grease injection port. The pressure sensors 201 are piezoresistive or capacitive sensors. The signal output terminal is connected to the central processing module 100 through an analog-to-digital converter interface. The sampling frequency of the pressure sensors 201 is configured to be no less than 50 Hz to capture the transient pressure decay waveform after pumping stops.

[0025] The attitude detection module 300 is used to acquire the mechanical geometric state data of the tunnel boring machine. The attitude detection module 300 includes an articulation sensor 301 and a propulsion sensor 302. The articulation sensor 301 is installed on the articulation cylinder at the connection between the middle shield and the tail shield and is used to detect the extension and retraction length of the grouped articulation cylinders. The data output terminal of the articulation sensor 301 is connected to the central processing module 100 and is used to calculate the spatial position and attitude of the tail shield relative to the tunnel segment. The propulsion sensor 302 is installed on the propulsion cylinder group and is used to detect the current propulsion displacement of the tunneling ring.

[0026] The injection module 400 serves as an actuator for pumping sealing grease into the sealing chamber. The injection module 400 includes several grease pumps 401 and control valves 402. Each set of grease pumps 401 is connected to a corresponding grease injection port via a hose. The grease pumps 401 are quantitative plunger pumps. The control valves 402 are connected in series in the pipeline between the grease pumps 401 and the grease injection ports. The control valves 402 are pneumatically or hydraulically driven shut-off valves. The opening and closing action of the shut-off valves is controlled by the central processing module 100. The control valves 402 are configured to cut off the fluid passage and isolate the pumping pipeline from the sealing chamber when the grease pumps 401 stop running.

[0027] The central processing module 100 establishes a bidirectional communication connection with the acquisition module 200, the attitude detection module 300, and the injection module 400 through an industrial fieldbus. The industrial fieldbus adopts the PROFIBUS (Process Fieldbus) protocol, the PROFINET (Process Field Network) protocol, or the EtherCAT (Ethernet Control Automation Technology) protocol. The central processing module 100 is configured to calculate the dynamic gap based on the geometric data transmitted by the attitude detection module 300, determine the sealing status based on the transient pressure data transmitted by the acquisition module 200, and generate control commands to adjust the operating parameters of the injection module 400.

[0028] See attached document Figure 2 The method provided by this invention is executed periodically by the central processing module 100, and a single control cycle covers the entire process of data acquisition, model solving, grease injection execution, feature extraction and feedback adjustment.

[0029] The central processing module 100 acquires real-time operating status data of the tunnel boring machine from the acquisition module 200 and the attitude detection module 300 via an industrial fieldbus. The operating status data includes the stroke data of the articulated cylinders, the group stroke data of the articulated cylinders, and the background pressure value at each grease injection hole.

[0030] To determine the physical boundary conditions at each grease injection hole, the central processing module 100 calculates the horizontal eccentricity of the shield tail center relative to the segment ring center based on the stroke difference of the articulated cylinders. and vertical eccentricity Combined with the shield tail radius , segment outer diameter And the pre-stored shield deformation compensation amount Calculate the first according to the following geometric relationship Real-time radial clearance value at each grease injection hole : ; in, For the first The circumferential angle position at each grease injection hole; Indicates the first The circumferential angular position of each grease injection hole on the circumference. This step maps mechanical attitude data to geometric constraints for fluid control.

[0031] The central processing module 100 constructs a rheological response benchmark model under the current working condition based on the real-time radial clearance value. This step is based on the physical principle that the overall stiffness of the shield tail sealing system increases as the clearance decreases, and high stiffness will lead to faster fluid pressure decay.

[0032] The central processing module 100 calls the pre-stored sealing brush material characteristic data and sealing grease rheological parameter table in the storage unit. First, based on the real-time radial gap value... Calculate the equivalent bulk modulus of the sealed cavity The calculation formula is as follows: ; in, Indicates the equivalent bulk modulus (unit: MPa); The bulk modulus of the sealing grease (unit: MPa) is taken as 1800 MPa. To determine the number of sealing brush passes, typically ; For the first Stiffness weighting coefficient of the brush; The reference elastic modulus (unit: MPa) of the wire brush bundle ranges from 50 MPa to 150 MPa. The initial free height of the wire brush (unit: mm) is determined by the wire brush manufacturing specifications. To compress the nonlinear exponent, the value ranges from 1.5 to 3.0.

[0033] Subsequently, the central processing module 100 is based on the equivalent bulk modulus. and the zero-shear dynamic viscosity of sealing grease The theoretical stress relaxation time constant was calculated based on Maxwell's viscoelastic model. : ; Theoretical stress relaxation time constant This is used to characterize the theoretical rate at which pressure naturally decays over time when the medium inside the sealed cavity is pure grease and the sealing structure is intact, given the current geometric clearance.

[0034] The central processing module 100 sends an action command to the injection module 400 to execute pulsed grease injection. The injection module 400 opens the control valve 402 and drives the grease injection pump 401 to operate, injecting a preset volume of sealing grease into the sealing cavity. During the operation of the grease injection pump 401, the central processing module 100 calculates the pressure rise slope of the data fed back by the pressure sensor 201. .

[0035] If the slope of the pressure rise If the preset rigid blockage threshold is exceeded, a physical blockage is determined to have occurred in the grease injection line. The central processing module 100 immediately stops the grease injection pump 401 and triggers an abnormal alarm. The rigid blockage threshold is set to 3 to 5 times the normal pumping pressure rise rate. If the pressure rise slope is... If the leakage value is below a preset leakage threshold (e.g., close to zero), it is determined that the pipeline is disconnected or there is a through-flow leakage channel in the sealed cavity.

[0036] When the amount of grease injected reaches the preset volume, the central processing module 100 controls the grease pump 401 to stop operating and simultaneously closes the control valve 402. The system enters the silent observation stage, and the acquisition module 200 continuously acquires the pressure signal in the sealed cavity at a frequency of not less than 50 Hz to form a transient pressure decay sequence after the pump stops.

[0037] The central processing module 100 extracts pressure decay data within a preset time window (e.g., 0 to 15 seconds after pump shutdown), and uses a nonlinear least squares method to fit the pressure decay sequence with an exponential function. The fitting model is as follows: ; in, for The pressure value at any given moment; This represents the steady-state residual pressure. This represents the pressure attenuation rate. This is an exponential decay term, describing the decay process of the transient component over time; The measured stress relaxation time constant is to be extracted. The central processing module 100 extracts the measured stress relaxation time constant from the fitting results. .

[0038] The central processing module 100 compares the measured stress relaxation time constant with the theoretical stress relaxation time constant and calculates the relaxation coupling index. To eliminate the influence of geometric gaps on the decision, the relaxation coupling index is defined using a normalized ratio. The formula for calculating the relaxation coupling index is: ; in, The measured stress relaxation time constant to be extracted; is the theoretical stress relaxation time constant.

[0039] The central processing module 100 identifies the physical state of the sealed cavity and adjusts the control strategy based on the numerical range of the relaxation coupling index. If the absolute value of the relaxation coupling index is less than the preset tolerance threshold... (For example If the sealing condition is determined to be normal, maintain the current grease injection parameters.

[0040] If the relaxation coupling exponent is less than the negative tolerance threshold ( This indicates the presence of water intrusion within the sealed cavity. This is because water's viscosity is much lower than that of sealing grease, and water lacks viscoelastic memory effect, resulting in a significantly faster pressure decay rate than theoretically expected (i.e.,...). (The value decreases significantly). At this point, the central processing module 100 switches to high-pressure replacement mode, and the instruction injection module 400 continuously pumps in grease until the relaxation coupling index returns to the normal range.

[0041] If the relaxation coupling exponent is greater than the positive tolerance threshold ( This indicates the presence of air pockets or sealing brush elastic failure within the sealed cavity. This is because the compressibility of the gas compensates for the pressure decay, or the sealing brush failure reduces the cavity stiffness, causing the pressure decay rate to be significantly slower than theoretically expected (i.e.,...). (The size increases significantly). At this time, the central processing module 100 switches to the exhaust and filling mode, and the instruction injection module 400 reduces the single pulse grease injection speed and increases the grease injection frequency.

[0042] See attached document Figure 2 In this embodiment, the central processing module 100 is configured to execute a tail shield gap calculation program. This program, based on the mechanical structural parameters and real-time attitude data of the tunnel boring machine, establishes a relative positional relationship model between the inner wall of the tail shield and the outer wall of the tunnel segments through coordinate transformation. The physical significance of this step lies in establishing the geometric boundary conditions for fluid control: the tail shield sealing brush, as an elastic porous medium, has porosity and mechanical stiffness that strictly depend on the degree of compression, which is directly determined by the current radial gap.

[0043] Establish the reference coordinate system and initialize the parameters for the shield tail cross-section. The system establishes a three-dimensional Cartesian coordinate system with the center of the shield machine's cut-out ring as the origin, the horizontal rightward direction as the positive X-axis, the vertical upward direction as the positive Y-axis, and the direction opposite to the shield machine's tunneling axis as the positive Z-axis. The following geometric parameters are initialized and set in the storage unit of the central processing module 100: shield tail radius... , segment outer diameter and design nominal gap ,in .

[0044] The system defines the number of grease injection holes as follows: , No. The circumferential angle position of each grease injection hole on the circumference is: The angle starts at 0 degrees from the positive half of the Y-axis, and is positive in the clockwise direction.

[0045] The system acquires articulation angle data and calculates the tail shield center deflection attitude. The attitude detection module 300 collects real-time stroke data of the articulation cylinder assembly between the middle and tail shields of the tunnel boring machine. The articulation cylinders are divided into four sections: upper, lower, left, and right. The system acquires the average extension / retraction length of the cylinders in each section. The central processing module 100 calculates the horizontal articulation angle based on the stroke difference between the left and right section cylinders. The vertical hinge angle is calculated based on the stroke difference between the upper and lower hydraulic cylinders. The calculation of the hinge angle involves the trigonometric function relationship between the diameter of the cylinder distribution circle and the stroke difference. Those skilled in the art can directly obtain this relationship based on the geometric relationship given in the tunnel boring machine manual. This is a conventional technical method in the field and will not be elaborated here.

[0046] Calculate the eccentricity of the shield tail cross-section center relative to the segment ring center. The shield tail structure, as a rigid body, has its spatial position relative to the segments determined by the deflection of the hinge angle and the shield tail length. Define the axial distance from the shield machine hinge center to the cross-section containing the shield tail grease injection holes as... The central processing module 100 calculates the horizontal eccentricity of the shield tail center in the X-axis direction based on the following geometric relationship. Vertical eccentricity in the Y-axis direction : ; ; in, The horizontal hinge angle is positive when deflected to the right. The vertical hinge angle is positive when the head is tilted upwards. This is the correction value for the subsidence deflection caused by the self-weight of the shield tail being suspended. This value is pre-determined by the structural mechanics simulation of the tunnel boring machine and stored in the system.

[0047] A dynamic gap calculation model considering the compressive deformation of the shield shell is constructed. In a high-confined aquifer environment, external water and soil pressure acting on the outer wall of the shield shell causes inward elastic radial deformation of the shield tail shell. The system has a pre-stored lookup table of shield shell radial deformation based on finite element analysis, and the shield shell compressive deformation compensation amount... External environmental pressure The function, where The earth pressure is measured in real time by earth pressure sensors installed on the earth chamber baffle or outer wall of the shield. The central processing module 100 combines the design nominal clearance, the projected component of the eccentricity in the radial direction of the grease injection hole, and the radial deformation of the shield shell to calculate the first... Real-time radial clearance value at each grease injection hole .

[0048] This step involves calculating the real-time radial clearance value. The macroscopic attitude data and environmental load data of the tunnel boring machine are mapped to the microscopic geometric boundary conditions at each specific grease injection point, and the real-time radial clearance value is calculated. It is then transmitted to the rheological response benchmark model building module as an input variable for calculating the equivalent cavity stiffness.

[0049] See attached document Figure 2 After obtaining the eccentricity data of the shield tail center relative to the segment center, the central processing module 100 further executes the circumferential gap distribution calculation program based on vector projection.

[0050] Calculate the geometric eccentricity projection at the grease injection points. Since the shield tail is a rigid cylinder, when its center shifts, the distance between the grease injection points at different angles on the circumference and the surface of the segment will change non-uniformly. The physical essence of this change is the projection of the shield tail center offset vector onto the radial direction of each grease injection hole.

[0051] Central processing module 100 based on horizontal eccentricity and vertical eccentricity Calculate the first trigonometric function projection rule. Geometric clearance correction at each injection hole Based on the defined coordinate system (0 degrees for the positive Y-axis, and positive for clockwise), the projection calculation formula is as follows: ; in, This refers to the horizontal eccentricity. This refers to the vertical eccentricity. For the first The circumferential angle position at each grease injection hole, when the calculation result... When the value is positive, it indicates that the shield tail is moving closer to the segment at that angle, resulting in a reduction in the physical gap.

[0052] This paper introduces a method for correcting the elastic deformation of the shield shell in deep-water environments. Under conditions of high-pressure aquifers, the outer wall of the tunnel boring machine (TBM) shield shell is subjected to enormous hydrostatic and earth pressures, resulting in radial elastic contraction. For ultra-large diameter TBMs with a diameter greater than 14 meters, under high water pressure conditions exceeding 0.5 MPa, the radial deformation of the shield shell is typically between 1 mm and 5 mm. This deformation is not negligible for controlling millimeter-level sealing gaps.

[0053] The central processing module 100 acquires the real-time environmental pressure values ​​measured by the external water and soil pressure sensor from the acquisition module 200. The central processing module 100 uses the equivalent radial stiffness method to calculate the shield shell's compressive deformation compensation. The calculation formula is as follows: ; in, Real-time environmental pressure value measured by water and soil pressure sensor (unit: MPa); The radial compressive stiffness coefficient of the shield tail shell (unit: MPa / mm) is pre-calibrated by finite element simulation based on the material properties (elastic modulus), wall thickness, and reinforcing rib structural parameters of the shield machine shell.

[0054] The central processing module 100 synthesizes the final real-time radial clearance field and designs the nominal clearance. Geometric clearance correction due to attitude and the amount of compensation for the compressive deformation of the shield shell Perform linear superposition to calculate the first... One injection port is located at The actual physical gap at a given moment Actual physical gap The calculation formula is as follows: ; in, For the first One injection port is located at The actual physical gap at any given moment; The nominal clearance of the shield tail structure under conditions of no external force and no eccentricity; For the first The circumferential angle position at each grease injection hole.

[0055] Through this step, the central processing module 100 completes the mapping from mechanical attitude to fluid boundary. For each grease injection hole, the system independently calculates and outputs a corresponding... The value serves as the sole geometric input variable for subsequent calculations of the equivalent stiffness of the sealed cavity.

[0056] See attached document Figure 2 In obtaining the first One injection port is located at The actual physical gap at a given moment Subsequently, the central processing module 100 further executes the physical field mapping program. The physical principle of this program is to treat the shield tail sealing cavity as an equivalent composite elastic system composed of fluid (grease) and solid (wire brush) in parallel. When the injection of sealing grease causes a change in the pressure inside the cavity, the overall volumetric stiffness of the system depends on the compressibility of the fluid and the rebound stiffness of the wire brush skeleton under the current compression.

[0057] A solid-liquid coupling stiffness model of the sealed cavity is constructed. This invention uses the equivalent bulk modulus of the sealed cavity... Defined as the linear superposition of the bulk modulus of sealing grease and the equivalent modulus of wire brush.

[0058] For the bulk modulus of sealing grease Its physical meaning is the pressure increment required for a unit volume relative change. The central processing module 100 reads the pre-stored grease physical property parameters in the storage unit, and within the common shield tail sealing temperature range (15℃ to 40℃), the bulk modulus of the sealing grease. The value range is from 1500MPa to 2200MPa.

[0059] The nonlinear compressive stiffness contribution of the wire brush assembly is calculated. As an elastic element of the sealing system, the stiffness of the wire brush increases nonlinearly with the increase of compression. In the physical model, the wire brush is regarded as a set of variable stiffness springs.

[0060] The central processing module 100 bases its data on the real-time radial clearance value. Determine the compression state of the wire brush and define its free height as... This parameter represents the natural elongation length of the wire brush when it is not compressed. For a typical three-brush structure (front brush, middle brush, and tail brush), the grease injection hole is usually located between two brushes. The system determines the stiffness weighting coefficient of each brush relative to the grease injection hole area based on the axial distance of the grease injection hole relative to the front and rear brushes. Stiffness weighting coefficient The calculation formula is: ; in, For the first The axial distance from the centerline of the brush to the center of the current grease injection hole; This represents the total axial distance between the centerlines of the two wire brushes before and after the grease injection hole. This formula indicates that the closer the wire brush is to the grease injection hole, the greater the influence of its stiffness characteristics on the pressure in that area.

[0061] A real-time equivalent bulk modulus benchmark is generated. The central processing module 100 couples the fluid modulus with the solid skeleton modulus to calculate the equivalent bulk modulus at the current moment and at the current grease injection hole. The calculation process uses the following mixed stiffness formula: ; in, Indicates the first At each grease injection hole Equivalent bulk modulus at time (unit: MPa); The bulk modulus of the sealing grease (unit: MPa) is taken as 1800 MPa. To determine the number of sealing brush passes, typically ; For the first Stiffness weighting coefficient of the brush; The reference elastic modulus (unit: MPa) of the wire brush bundle ranges from 50 MPa to 150 MPa. The initial free height of the wire brush (unit: mm) is determined by the wire brush manufacturing specifications. To compress the nonlinear exponent, the value ranges from 1.5 to 3.0.

[0062] parameter and The offline calibration method was adopted to determine the following: Before the shield tunneling started, the same batch of wire brush samples were subjected to compression tests using a pressure testing machine, the stress-strain curves were recorded, and the specific values ​​were obtained by power function fitting and stored in the central processing module 100.

[0063] The above formula establishes a quantitative relationship between geometric clearance and system stiffness: when the real-time radial clearance value at the shield tail... When the value is reduced, the compression ratio of the wire brush (the item in parentheses) increases, leading to... Exponential increase, The value is then used as the key denominator term in the calculation of the fluid stress relaxation time constant.

[0064] See attached document Figure 2 The equivalent bulk modulus of the sealed cavity was established. Afterwards, the central processing module 100 continues to execute the calculation steps for the theoretical rheological response parameters.

[0065] Determine the reference rheological parameters of the sealing grease. Since the shield tail sealing grease is a non-Newtonian fluid, its viscosity characteristics change with shear rate and temperature. In the pressure relaxation stage (zero flow rate state) after the grease pump stops, the key physical quantity that determines the pressure decay rate is the zero shear dynamic viscosity.

[0066] The central processing module 100 acquires real-time temperature data of the shield tail area through the acquisition module 200. The central processing module 100 uses the Arrhenius equation of state to calculate the zero-shear dynamic viscosity at the current temperature. The calculation formula is as follows: ; in, The zero-shear dynamic viscosity at the current temperature (unit: MPa·s); is the pre-exponential factor constant for oil and fat materials, with a value range of 1.0 × 10⁻⁶. -5 Up to 5.0×10 -4 MPa·s; The activation energy is the flow rate, ranging from 25 to 45 kJ / mol. The gas constant is 8.314 J / (mol·K); Thermodynamic temperature (unit: K), parameter and The rheological test report provided by the sealing grease supplier is entered into the system.

[0067] This invention calculates the theoretical stress relaxation time constant based on Maxwell's viscoelastic model to describe the dynamic response of the sealed cavity. In this model, the sealing system is equivalent to a purely elastic spring (characterized by...). ) and a purely viscous damper (characterized by The theoretical stress relaxation time constant of a system composed of series connections. This characterizes the decay of the internal stress of the system to its initial value under constant strain. The time required.

[0068] Central processing module 100 calls the calculated equivalent bulk modulus and the obtained zero-shear dynamic viscosity The theoretical stress relaxation time constant under the current operating condition is calculated using the following formula. : ; in, Indicates the first One injection port at The theoretical stress relaxation time constant at time t (unit: s); This indicates the zero-shear dynamic viscosity of the sealing grease (unit: MPa·s). The equivalent bulk modulus of the sealed cavity (unit: MPa).

[0069] According to this formula, the theoretical relaxation time is inversely proportional to the system stiffness. When the shield-tail gap decreases, the equivalent bulk modulus increases. As the pressure increases, the theoretical rate of pressure decay will accelerate. (The pressure decreases); conversely, when the gap increases and stiffness decreases, the pressure decay rate will slow down.

[0070] A theoretical pressure decay baseline curve is generated. To establish a benchmark for comparison, the central processing module 100 constructs an exponential decay equation describing the evolution of pressure over time under ideal conditions.

[0071] Define the time when the grease pump stops as The peak pressure at the moment the pump stops is Define steady-state residual pressure This represents the external background soil and water pressure at the current location of the grease injection hole. This value is determined by real-time readings from nearby soil pressure sensors, and the ideal pressure decay trajectory is shown. Follow the following mathematical model: ; in, for Theoretical predicted pressure value at any given time; The peak pressure at the instant the pump stops is obtained by pressure sensor 201 at the instant the pump stops. This represents the steady-state residual pressure. Indicates the moment the grease pump stops; Indicates time; The duration of relaxation experienced.

[0072] The pressure decay trajectory The pressure response characteristics were characterized under standard operating conditions where the sealing structure was intact, the cavity was filled with pure grease, and there was no air pocket. In subsequent control steps, the system will fit and compare the real-time collected pressure decay data with this benchmark curve, and identify abnormalities in the medium composition (such as water or gas) within the sealed cavity by the direction of deviation.

[0073] See attached document Figure 2 During the pulsed grease injection process initiated by the injection module 400, the central processing module 100 executes a real-time flow resistance monitoring program in parallel. This step, based on fluid mechanics principles, utilizes the pressure response characteristics of a fluid when compressed within a confined space to determine the physical connectivity integrity of the grease injection pipeline.

[0074] The transient pressure sequence during the pumping phase is acquired. After the grease pump is turned on, the acquisition module 200 uses a set sampling frequency. (For example, 100Hz to 500Hz) The pressure sensor value at the grease injection port is continuously read. Due to the reciprocating motion characteristics of the plunger pump, which generate high-frequency pressure pulsation noise, the central processing module 100 performs a moving average filtering process on the raw pressure data. The length of the moving window... The sampling points are set to 5 to 10, and the processed pressure values ​​are... The arithmetic mean of the original data within the window is used to preserve the macroscopic trend of pressure increasing with injection volume, while filtering out mechanical vibration noise.

[0075] Calculate the real-time pressure rise rate; select central processing module 100. A preset time window before the time. (Value range 0.2 seconds to 0.5 seconds), extract the pressure data sequence within this window. The total number of sampling points within the window at this time... Determined by the sampling frequency, i.e. Linear regression analysis of time and pressure data within this time window was performed using the least squares method to calculate the pressure rise rate. Pressure rise rate The calculation formula is as follows: ; in, Indicates the rate of pressure rise (unit: MPa / s); This represents the total number of sampling points within the regression analysis window; For the first in the window Timestamp of each sampling point; For the first in the window The pressure values ​​after filtering at each sampling point, when used with the least squares method, can effectively smooth out single-point measurement errors and provide a robust slope estimate that reflects the current pipeline volumetric stiffness characteristics.

[0076] The threshold for determining flow resistance conditions is pre-stored in the central processing module 100, which has a reference boost rate. and the rigid blocking threshold determined based on this benchmark. and leakage threshold The system, based on the fluid continuity equation and the principle of bulk modulus, calculates in real time... Compare with the threshold.

[0077] Reference boost rate The method for obtaining the data is as follows: During the tunnel boring machine commissioning phase, the grease injection pipeline is connected to the calibration container. A standard pumping test is conducted under conditions of unobstructed pipeline and no back pressure. The average slope during the pressure rise phase is statistically analyzed as... .

[0078] rigid blocking threshold Defined as: ; in, This is the blocking determination coefficient, with a value ranging from 3.0 to 5.0; if The condition is determined to be a hard blockage in the pipeline. When the end of the pipeline is blocked, the effective volume is... Minimal, depending on pressure increment In the injection volume Under constant conditions, the smallest This will lead to an increase in pressure. It has increased exponentially.

[0079] Leakage threshold Defined as: ; in, This is the leakage determination coefficient, with a value ranging from 0.1 to 0.2; if If the pipeline is ruptured, it is determined to be a pipeline leak or disconnection. When the pipeline is ruptured, the fluid flows to the atmospheric environment or low-pressure area with the least resistance, and it is impossible to establish a high-pressure gradient in the pipeline, which is manifested as the pressure hardly rising.

[0080] like This is considered a normal grease injection condition. At this time, the grease overcomes the resistance along the flow path and the back pressure of the shield tail to enter the sealing cavity, and the pressure rises linearly and steadily.

[0081] For abnormal operating conditions, when the system determines that there is a hard blockage or leakage in the pipeline, the central processing module 100 triggers the hardware interlock, immediately sends a shutdown command to the injection module 400, forcibly shuts down the grease pump and control valve, and outputs the corresponding fault alarm signal. This step ensures that the pressure decay data used for stress relaxation analysis in subsequent steps must come from a physically connected and unobstructed hydraulic system. Only when the judgment result is a normal grease injection condition and the grease injection volume reaches the preset volume will the central processing module 100 control the grease pump to stop normally and trigger the subsequent transient stress relaxation feature extraction process after pump shutdown.

[0082] See attached document Figure 2After the grease pump stops operating, the system enters the fluid rheological response analysis stage. This stage utilizes the natural pressure dissipation characteristics of fluid within a confined space to invert the rheological parameters of the sealed cavity. The central processing module 100 executes a pressure decay curve fitting program to calculate the measured stress relaxation time constant from discrete sensor sampling sequences.

[0083] When capturing the effective pressure decay data window, the fluid in the pipeline experiences a high-frequency hydraulic shock (i.e., water hammer effect) due to a sudden change in momentum at the moment the grease pump is shut off. This transient fluctuation interferes with the extraction of rheological characteristics. To eliminate this mechanical noise, the central processing module 100 introduces a stabilization delay. The value ranges from 0.05 seconds to 0.1 seconds.

[0084] System intercept time range The pressure sampling sequence within is used as the fitting sample set, where, The observation window length for decay is set to 2.0 to 5.0 seconds. This length is chosen based on the typical relaxation half-life of the sealing grease to ensure that the window contains sufficient curvature information to characterize the decay rate. The set of sampling points within this window is denoted as... ,in This represents the total number of sampling points.

[0085] A logarithmically linearized model is constructed based on Maxwell's viscoelastic constitutive equation. Ideal pressure decay follows an exponential law. In order to achieve parameter identification with low computing power consumption and high stability in embedded systems, the central processing module 100 uses the logarithmic transformation method to transform the nonlinear exponential fitting into a linear regression problem.

[0086] The original physical equation is: ; After rearranging the terms and taking the natural logarithm, we obtain the linearized equation: ; make slope ,intercept At this point, the problem is transformed into analyzing the transformed data points. Perform univariate linear regression, where, This represents the system's time constant.

[0087] In this step, the system performs data validation preprocessing: traversing the sampling points. Only retain those that meet the requirements. The sampling points enter the regression queue, among which For steady-state residual pressure, The preset tolerance threshold is 0.01 MPa. If the number of remaining sampling points after rejection is less than the total number of sampling points. If 50% of the samples are negative, the sample is deemed invalid.

[0088] The central processing module 100 performs least squares regression fitting and uses the least squares method to solve for the optimal slope of the linear equation. Optimal slope The calculation formula is as follows: ; in, This represents the total number of sampling points; For the first The relative time (s) of each sampling point; For the first Pressure values ​​after logarithmic transformation of each sampling point.

[0089] The optimal slope was calculated. Then, the system first verifies The sign. Since pressure physically exhibits decay, the optimal slope must be less than 0; if the calculation result... (Indicating that the pressure has not decreased or has even increased), then the data is considered abnormal (external interference exists), and the calculation is terminated. If Then, the measured stress relaxation time constant is calculated according to the physical definition. : ; Should The value is a comprehensive physical quantity that characterizes the hardness and viscosity of the sealed cavity and the fluid.

[0090] Goodness-of-fit testing and parameter validity determination: To quantify the reliability of the calculation results, the central processing module 100 calculates the goodness-of-fit coefficient. goodness-of-fit coefficient The calculation formula is as follows: ; in, This is the logarithmic transformation value of the actual observed data; The predicted value calculated based on the regression equation ; This represents the mean of the observed data.

[0091] The system presets a goodness-of-fit threshold. The value ranges from 0.85 to 0.90. The fitting was deemed valid, and the measured stress relaxation time constant was extracted. Store in the register; if The system determines that the decay data in this cycle does not conform to the laws of viscoelasticity, discards the current result, and retains the data from the previous cycle. The process remains unchanged, while abnormal events are recorded in the log.

[0092] See attached document Figure 2After obtaining the measured stress relaxation time constant With respect to the theoretical stress relaxation time constant Subsequently, the central processing module 100 executes the state identification program. This program, based on the normalization principle, transforms the absolute time constant, which is affected by multiple physics fields, into a dimensionless relative index that reflects the essential properties of the medium.

[0093] The relaxation coupling index (RCI) is calculated, and the central processing module 100 calls the calculated measured stress relaxation time constant. and the calculated theoretical stress relaxation time constant Perform ratio calculations and relax the coupling index. The calculation formula is as follows: ; in, For the first Each injection port at time The relaxation coupling index (dimensionless). For the first Each injection port at time The measured stress relaxation time constant (unit: s) was obtained by fitting field pressure decay data. For the first Each injection port at time The theoretical stress relaxation time constant (unit: s).

[0094] The physical significance of this calculation step lies in decoupling: the theoretical stress relaxation time constant. The RCI index already includes information on the changes in temperature (affecting viscosity) and shield tail clearance (affecting stiffness) at the current moment. Therefore, by performing a division operation, the RCI index eliminates the interference of temperature fluctuations and mechanical clearance changes on the monitoring results. At this point, the numerical change of RCI depends only on the differences in the physical properties of the medium components (grease, water, air) in the sealed cavity.

[0095] Define state identification thresholds. The central processing module 100 has two preset sets of state determination thresholds: water intrusion determination threshold. Cavity / Gas Detection Threshold .

[0096] The threshold was determined through offline experimental calibration. Water intrusion detection threshold The value ranges from 0.4 to 0.7. The calibration method is as follows: a mixture of oil and water with a water content of 30% (mass fraction) is prepared in a laboratory environment, and its stress relaxation time constant is measured. ,calculate Because water has a much lower viscosity than oil, the equivalent viscosity of the system decreases after mixing, leading to a change in the system's time constant. Decrease.

[0097] Cavity / Gas Detection Threshold The value ranges from 1.3 to 2.0. The calibration method is as follows: introduce 10% air by volume into the simulation chamber and measure its stress relaxation time constant. Due to the bulk modulus of the gas... (Approximately 0.1 MPa) is much smaller than the bulk modulus of oils. (Approximately 1800 MPa), the presence of gas significantly reduces the system's equivalent stiffness. According to the time constant of the formula system Decreasing the denominator leads to a decrease in the system's time constant. Increase.

[0098] To achieve automatic identification and closed-loop control of the sealing state based on the RCI index, this embodiment pre-constructs a hierarchical judgment logic based on rheological characteristics. The system presets two key dimensionless judgment thresholds: a water intrusion judgment threshold (denoted as...). ) and airbag detection threshold (denoted as ).

[0099] The physical meaning of these two thresholds is based on the compressibility and viscosity characteristics of the sealing medium: when low-viscosity slurry or water is mixed into the sealing cavity, pressure leakage is extremely rapid, leading to a decrease in the RCI value; while when highly compressible air accumulates in the sealing cavity to form an air pocket, the pressure maintenance capacity is artificially high, leading to an abnormally high RCI value. The specific judgment and decision-making logic is as follows: Water intrusion failure determination: If calculated in real time The system determines that the system is currently in a state of water intrusion or slurry intrusion. At this time, the risk of sealing medium loss is high, and the high-pressure replacement mode needs to be triggered. Airbag cavity determination: if calculated in real time The system determines that the airbag is currently in a loose connection state. At this time, the effective filling of the sealed cavity is insufficient, and the dense filling mode needs to be triggered. Normal state determination: If The system determines that the current sealing medium is in good condition and is in a normal sealing state, and maintains the standard maintenance mode.

[0100] Perform a sealing status classification determination. The central processing module 100 will calculate the results. The label of the sealing status of the current grease injection hole is output after comparing it with the above threshold. The specific judgment logic is as follows: Water intrusion failure state: if the conditions are met The system determines that external water pressure has intruded into the current grease injection area. Physically, this manifests as extremely rapid pressure decay, indicating a loss of the damping characteristics of a high-viscosity fluid. The central processing module 100 then updates the sealing status label. Marked as (High-pressure replacement mode).

[0101] Inflatable bladder underinflation state: if the conditions are met The system determines that there are gas cavities or incomplete grease filling in the current grease injection area. Physically, this manifests as extremely slow pressure decay, exhibiting low stiffness and high elasticity characteristics similar to a gas spring. The central processing module 100 will then display the sealing status label. Marked as (Dense Fill Mode).

[0102] Normal sealing condition: if the conditions are met The system determines that the current grease injection area is well-sealed and that the medium properties are consistent with the theoretical model. The central processing module 100 will then display the sealing status label. Marked as (Standard maintenance mode).

[0103] Generation of adaptive control parameters. Based on a defined sealing state label. The central processing module 100 looks up a table to generate a correction control command for the next grease injection cycle and sends it to the injection module 400.

[0104] like (High-pressure replacement mode): The system calls the pre-stored replacement parameter set. The specific control strategy is: the single injection volume of grease... Set the pressure to 1.2 to 1.5 times the standard reference value, while also setting the upper limit of the grease injection pressure. Set to 1.1 times the current external water and soil pressure, this strategy forces the inferior grease mixed with water out of the sealed cavity by increasing the injection volume and increasing the pressure gradient.

[0105] like (Dense Filling Mode): The system calls the pre-stored dense parameter set. The specific control strategy is to maintain the amount of fat injected in a single session. The time interval between two consecutive liposuction actions remains unchanged. Reduce to 50% of the standard value and decrease the grease injection flow rate. By reducing the value to 80% of the standard value, this strategy reduces fluid disturbance through high-frequency, low-speed injection, facilitating gas discharge through the tail brush gap under pressure.

[0106] like (Standard Maintenance Mode): The system maintains the current standard grease injection parameters, relying solely on the tunnel boring machine's advance speed fed back by the acquisition module 200. Perform linear scaling adjustments.

[0107] See attached document Figure 2 After confirming the sealing status of the current grease injection port label Subsequently, the central processing module 100 enters the multi-mode adaptive injection strategy execution stage. Based on fluid dynamics control principles, this stage reconstructs the medium distribution within the sealed cavity by dynamically adjusting the action parameters of the injection module 400.

[0108] Implement a high-pressure replacement strategy under water intrusion conditions. (When the seal status label...) Marked as This indicates that the external water and soil pressure is higher than the pressure inside the sealing cavity, causing the sealing grease to be diluted. The control objective at this time is to establish a strong positive pressure gradient.

[0109] Central processing module 100 calls the preset permutation gain coefficient. (Values ​​range from 1.2 to 1.5), calculate the corrected single injection volume. and the revised upper limit of grease injection pressure Single injection volume The calculation formula is as follows: ; Revised upper limit of grease injection pressure The calculation formula is as follows: ; in, The reference grease injection volume under standard operating conditions (unit: L); This is the displacement gain coefficient, and its physical meaning lies in compensating for the volume of ineffective grease carried away by water. This is the measured value of external soil and water pressure at the current location (unit: MPa). For safety overpressure margin, the value range is 0.2MPa to 0.5MPa.

[0110] The central processing module 100 sends control commands to the grease pump to increase the number of pumping strokes per unit time to meet the requirements. of Using the modified upper limit of grease injection pressure The excess grease volume creates an outward pressure gradient within the sealed cavity, forcing the emulsified and deteriorated grease-water mixture to be squeezed out through the gap between the tail brush and the tube segments, thereby replacing it with fresh grease.

[0111] Implement a dense filling strategy for airbag cavities, when In the (dense filling mode), it indicates that there is highly compressible gas in the sealed cavity. The control objective at this time is to discharge the gas without introducing fluid turbulence.

[0112] The central processing module 100 switches to high-frequency low-speed control mode to adjust the interval of the grease pump's action. and instantaneous injection flow rate Corrected action interval time The calculation is as follows: ; Corrected instantaneous flow rate The calculation is as follows: ; in, The grease injection interval in standard mode (unit: seconds); The frequency encryption coefficient ranges from 0.4 to 0.6. Pumping flow rate in standard mode (unit: L / min); This is the flow velocity suppression coefficient, with a value ranging from 0.7 to 0.9.

[0113] This strategy is designed based on the characteristics of laminar fluid flow: velocity suppression coefficient. This allows the injected grease to maintain a laminar flow state, utilizing the carrying effect of the high-viscosity fluid to smoothly push air bubbles to the discharge port, avoiding the formation of dead air cavities due to high-velocity turbulence and bubble breakage; frequency encryption coefficient This is to provide continuous thrust.

[0114] Execute the speed synchronization and following strategy under normal operating conditions. When At this time, the system executes follow-up control based on volume conservation. The central processing module 100 reads the tunnel boring machine's advance speed. (Unit: mm / min), and calculate the theoretical grease injection flow rate based on the shield tail geometric parameters. : ; in, The theoretical fat injection flow rate required at the current moment (unit: L / min); The tunnel boring machine's advance speed (unit: mm / min); The outer diameter of the shield tail (unit: mm); The theoretical radial clearance between the tail shield shell and the outer wall of the segment (unit: mm). The value is the grease loss coefficient, which takes into account the volume loss of grease adhering to the rough surface of the tunnel lining segments or the slight infiltration into the formation, and ranges from 1.1 to 1.3. This is the fill rate coefficient, with a value of 1.0; Unit conversion factor.

[0115] Central processing module 100 according to Dynamically adjust the operating frequency of the grease pump : ; in, This refers to the fixed displacement (in liters) of the grease injection pump per stroke. This step ensures that the volume of grease injected into the sealing cavity remains dynamically balanced with the void volume generated by the tunnel boring machine's propulsion, thus maintaining the stability of the sealing pressure.

[0116] Specific Implementation: Application Verification of Intelligent Control Method for Shield Tail Seal Based on Rheological Feedback This embodiment verifies the control method proposed in this invention using field data from a large-diameter slurry shield tunneling project. The target maintaining pressure of the sealed cavity was set at 0.65 MPa, and the data sampling frequency was 10 Hz.

[0117] Sealed medium condition identification and verification (corresponding appendix) Figure 3 ): Figure 3 The transient pressure relaxation characteristics acquired by the system during the pump stop interval (0-15 seconds) are demonstrated. The system recorded three typical pressure decay processes, with an initial peak pressure of 0.8 MPa and an ambient background pressure of approximately 0.6 MPa.

[0118] Water intrusion failure condition (thin light gray line in the figure): The pressure drops precipitously and rapidly decays to around 0.6 MPa of the background pressure within 2 seconds after the pump stops, indicating that the medium viscosity is extremely low and there is a through water intrusion channel.

[0119] Airbag / cavity condition (thick black line in the figure): The pressure decays slowly. After 15 seconds, the pressure inside the cavity is still maintained above 0.71 MPa. This indicates that there is highly compressible gas inside the sealed cavity, resulting in a large pressure relaxation time constant.

[0120] Under normal sealing conditions (middle gray line in the figure): the pressure exhibits a standard exponential decay characteristic, smoothly transitioning to near ambient pressure in about 10 seconds, indicating that the grease is fully filled and its viscoelastic characteristics are normal.

[0121] Full-process dynamic control response verification (corresponding appendix) Figure 4 ): Figure 4 This demonstrates the switching logic between the Relaxation Coupling Index (RCI) monitoring values ​​and the system control mode during the tunneling process from ring 1 to ring 100, and sets a water intrusion detection threshold for the system. Cavity / Gas Detection Threshold .

[0122] During normal tunneling: the relaxation coupling index fluctuates around 1.0, the system remains in standard maintenance mode, and routine grease injection is performed.

[0123] Water intrusion treatment stage: At the 30th ring, the relaxation coupling index was monitored to drop to about 0.4 (below the 0.6 threshold). The system judged that slurry or water intrusion had occurred and immediately switched to high pressure replacement mode to remove the inferior medium by increasing the grease injection pressure.

[0124] Airbag treatment phase: At the 70th ring, the relaxation coupling index was detected to suddenly increase to above 1.8 (above the 1.5 threshold). The system judged that there was an airbag or cavity and immediately switched to the dense filling mode to increase the amount of fat injected to fill the compressible space.

[0125] Comparison of voltage stabilization effect and economy (with corresponding appendix) Figure 5 ): Figure 5 The field application effects of the traditional pressure and flow dual control method (control group) and the method of the present invention (experimental group) were compared.

[0126] Pressure stability ( Figure 5 (Above figure): The target pressure was set at 0.65 MPa (shown by the horizontal line in the figure). The control group (light gray line / hollow circle) was affected by the change in the shield tail gap, resulting in large pressure fluctuations, oscillating between 0.4 MPa and 0.9 MPa; while the experimental group (black line / solid dot) maintained the pressure closely around 0.65 MPa through a stiffness compensation algorithm, without significant fluctuations.

[0127] Quantitative analysis of key indicators ( Figure 5 (See figure below): Statistical results show that after adopting the method of the present invention, the coefficient of variation of the sealing cavity pressure decreased from 18.5% in the control group to 6.2%, achieving precise pressure control; at the same time, due to the avoidance of excessive grease injection and ineffective leakage, the unit grease consumption decreased from 35.4 kg / ring to 29.8 kg / ring, saving about 15.8% of grease cost.

Claims

1. A high-pressure water layer super-large-diameter slurry shield shield tail sealing grease injection control system, characterized in that, It includes a central processing module (100), which calculates the real-time radial clearance value at the grease injection hole based on the mechanical geometric state data transmitted by the attitude detection module (300), and constructs a rheological response benchmark model to calculate the theoretical stress relaxation time constant; The central processing module (100) sends an action command to the injection module (400) to perform pulsed grease injection, and controls the injection module (400) to stop operating and enter the silent observation stage after the grease injection amount reaches the preset value; The central processing module (100) acquires the transient pressure decay sequence acquired by the acquisition module (200) during the silent observation phase, and fits the transient pressure decay sequence to extract the measured stress relaxation time constant. The central processing module (100) calculates the ratio of the measured stress relaxation time constant to the theoretical stress relaxation time constant to obtain the relaxation coupling index, identifies the physical state of the sealed cavity based on the numerical range of the relaxation coupling index, and generates control commands to adjust the operating parameters of the injection module (400).

2. The sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in a high-pressure aquifer as described in claim 1, is characterized in that... The central processing module (100) calculates the real-time radial clearance value at the grease injection hole based on the mechanical geometric state data transmitted by the attitude detection module (300), specifically including: Based on the stroke data of the articulated cylinder obtained by the attitude detection module (300), the horizontal and vertical eccentricity of the shield tail center relative to the segment ring center is calculated by coordinate transformation. Obtain external water and soil pressure data, and calculate the compensation amount of shield shell compression deformation based on the pre-stored shield shell radial compressive stiffness coefficient; The difference between the shield tail radius and the outer diameter of the segment is taken as the nominal clearance. The horizontal eccentricity and the projection components of the vertical eccentricity on the radial direction of the grease injection hole are subtracted from the nominal clearance, and the shield shell compression deformation compensation is also subtracted to obtain the real-time radial clearance value.

3. The sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in a high-pressure aquifer as described in claim 1, is characterized in that... The calculation of the theoretical stress relaxation time constant by constructing the rheological response benchmark model specifically includes: The compression ratio of the wire brush is determined based on the real-time radial gap value. The bulk modulus of the sealing grease is linearly superimposed with the nonlinear stiffness contribution value under the compression ratio to calculate the equivalent bulk modulus of the sealing cavity. Acquire real-time temperature data of the shield tail region and use the Arrhenius equation of state to calculate the zero-shear dynamic viscosity of the sealing grease at the current temperature; The theoretical stress relaxation time constant is obtained by dividing the zero-shear dynamic viscosity by the equivalent bulk modulus.

4. The sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in a high-pressure aquifer as described in claim 1, characterized in that, The specific steps for fitting the transient pressure decay sequence to extract the measured stress relaxation time constant include: The central processing module (100) extracts the pressure sampling sequence after a preset time delay from the stop time of the grease pump (401) as a valid data window; The central processing module (100) constructs a pressure decay mathematical model that includes steady-state residual pressure, pressure decay magnitude, and exponential decay term; The pressure attenuation mathematical model is subjected to logarithmic linearization transformation, and the parameters characterizing the attenuation rate of the transient component with time are obtained by least squares regression analysis. The reciprocal of the parameters is used as the measured stress relaxation time constant.

5. The sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in a high-pressure aquifer as described in claim 1, characterized in that, The central processing module (100) performs flow resistance monitoring logic during pulsed grease injection performed by the injection module (400): Calculate the pressure rise slope of the data fed back by the acquisition module (200); If the pressure rise rate exceeds the rigid blockage threshold, it is determined that the grease injection line is physically blocked and an abnormal alarm is triggered. If the pressure rise slope is lower than the leakage threshold, it is determined that the grease injection line is disconnected or there is a through leakage channel in the sealing cavity; When the pressure rise slope is determined to be between the leakage threshold and the rigid blockage threshold, the system is confirmed to be in normal grease injection condition, and the subsequent measured stress relaxation time constant extraction process is allowed to be triggered.

6. The sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in a high-pressure aquifer as described in claim 1, is characterized in that... Identifying the physical state of the sealed cavity based on the numerical range of the relaxation coupling index specifically includes: If the relaxation coupling index is less than the water intrusion determination threshold, it is determined that water has intruded into the sealed cavity, and the sealing state is marked as high-pressure replacement mode. If the relaxation coupling index is greater than the airbag cavity determination threshold, it is determined that there is an airbag cavity or the sealing brush elastic failure in the sealed cavity, and the sealing state is marked as dense filling mode. If the relaxation coupling index is between the water intrusion determination threshold and the airbag cavity determination threshold, the sealing state is determined to be normal, and the sealing state is marked as standard maintenance mode.

7. The sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in a high-pressure aquifer as described in claim 6, is characterized in that... When the sealing status is marked as the high-pressure replacement mode, the control commands generated by the central processing module (100) include: The preset displacement gain coefficient is used to amplify the baseline grease injection volume, and the single grease injection volume is calculated. Based on the current measured values ​​of external soil and water pressure and the safety overpressure margin, the upper limit of the grease injection pressure is set. The injection module (400) is instructed to continuously pump in sealing grease according to the calculated single injection volume and the upper limit of the injection pressure until the relaxation coupling index returns to the normal range.

8. The sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in a high-pressure aquifer as described in claim 6, is characterized in that... When the sealing state is marked as the dense filling mode, the control commands generated by the central processing module (100) include: The time interval between two adjacent pulse liposuction actions is shortened based on a preset frequency encryption coefficient; The instantaneous injection flow rate of a single pulse grease injection is reduced by a preset flow rate suppression coefficient, so that the injected sealing grease remains in a laminar flow state to expel gas.

9. The sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in a high-pressure aquifer as described in claim 6, is characterized in that... When the sealing status is marked as the standard maintenance mode, the control commands generated by the central processing module (100) include: Obtain the tunnel boring machine's advance speed and shield tail geometric parameters, and calculate the theoretical grease injection flow rate based on the principle of volume conservation; The operating frequency of the injection module (400) is dynamically adjusted according to the theoretical grease injection flow rate to keep the volume of the injected sealing grease in balance with the void volume generated by the tunnel boring machine's propulsion.

10. The sealing grease injection control system for the tail of a large-diameter slurry shield tunnel in a high-pressure aquifer as described in claim 1, characterized in that, The acquisition module (200) includes a plurality of pressure sensors (201) distributed along the circumferential direction of the shield tail. Each grease injection hole position corresponds to one pressure sensor (201). The pressure sensor (201) is used to acquire the transient pressure decay waveform after the pumping stops. The injection module (400) includes a plurality of grease pumps (401) and a control valve (402) connected in series in the grease injection pipeline. The control valve (402) is used to cut off the fluid passage to isolate the pumping pipeline from the sealed chamber when the grease pumps (401) stop running.

Images