A large slope inclined shaft TBM tunneling method

Abstract

The present application relates to a kind of large-gradient inclined shaft TBM tunneling method, belongs to large-gradient inclined shaft full-face tunneling technical field in the field of tunnel engineering. For 15°-35° large-gradient inclined shaft, double-support TBM host is prone to slide along axis, support force and propulsion force imbalance and technical problems such as muck conveying is prone to accumulation and jam, the method is to establish tunneling reference after advancing a stroke, real-time monitoring double-main support shoe group support force, based on the weight and inclination of host to calculate sliding component force, combined with safety margin and friction coefficient to determine support force target value, dynamically match double-support force and total thrust of propulsion force;After stroke is completed, keep support state and move host forward, with screw conveyor drive motor current as feedforward variable, according to proportion linkage control linear speed of rear belt conveyor.This method is mainly used for safe and efficient tunneling construction of large-gradient inclined shaft TBM, to ensure tunneling stability and muck conveying smoothness.

Description

Technical Field

[0001] This invention relates to the field of inclined shaft excavation technology. More specifically, this invention relates to a method for TBM excavation of steep inclined shafts. Background Technology

[0002] In the construction of water conservancy and hydropower projects, transportation tunnels, and mine roadways, inclined shafts serve as crucial channels for ventilation, drainage, transportation, and pipeline laying, with increasingly widespread applications. As construction extends to deeper and more complex geological conditions, more and more inclined shafts need to be constructed under steep slope conditions. The most common angle between the shaft axis and the horizontal plane is between 15° and 35°. This slope range makes it difficult to achieve efficient excavation using traditional drill-and-blast methods and places stringent requirements on the construction stability of full-face tunnel boring machines (TBMs). Due to their stable support and high excavation efficiency, dual-support full-face tunnel boring machines have become one of the mainstream equipment for excavating such steep inclined shafts.

[0003] During the aforementioned steep-slope TBM tunneling process, the weight of the main unit itself generates a significant downward force along the shaft axis. This force dynamically changes with the tunneling inclination angle and is a core factor affecting tunneling stability. In existing dual-support TBM tunneling, the control of the tensioning force of the first and second main support shoe groups and the total thrust of the propulsion hydraulic cylinders is mostly based on fixed parameters set according to construction experience in horizontal or gently sloping tunnels, or only simple manual fine-tuning is performed, failing to fully consider the influence of the downward force due to gravity under steep slopes. Summary of the Invention

[0004] Another objective of this invention is to provide a TBM tunneling method for steep inclined shafts, which solves the problems of low tunneling safety and poor efficiency caused by the instability of the dual-support TBM main unit due to the influence of gravity sliding force in inclined shafts with a steep slope of 15°-35°, the inability to dynamically match the support force, propulsion force and sliding force, and the lack of coordination between the speed of the excavated soil conveying line and the output. This invention overcomes the dilemma that traditional fixed parameter control cannot simultaneously take into account anti-sliding, shaft wall protection and tunneling efficiency.

[0005] This addresses the problem that when the TBM main unit moves forward in a steep inclined shaft, the belt conveyor relies solely on a single signal of the screw conveyor current to control its speed, lacking feedback correction. This can easily lead to soil accumulation or slippage due to load fluctuations, making it unsuitable for real-time soil transportation needs. This solution improves the accuracy of conveying control.

[0006] This invention addresses the problem of insufficient quantitative basis for judging the working condition when abnormal torque occurs in belt conveyors, making it difficult to distinguish different abnormal types such as stable load changes, large material jamming, and continuous overload, leading to blind handling measures and easy exacerbation of the fault. It aims to achieve accurate working condition identification.

[0007] To address the lack of targeted control strategies for different abnormal operating conditions of belt conveyors, the inability of a single handling method to adapt to various faults, which can easily lead to equipment damage or interruption of excavated soil transportation, affecting the continuity of tunneling on steep slopes, and to improve the scientific nature of fault handling.

[0008] To address the issues that when tunneling with a TBM on a steep slope, monitoring only the support shoe tension cannot predict the bearing state of the shaft wall, and that fixed early warning thresholds are not suitable for different geological conditions and can easily overlook potential damage risks to the shaft wall, this invention aims to provide early warnings for shaft wall safety.

[0009] The solution addresses the problem of insufficient graded control mechanism when the displacement rate of the hydraulic cylinder exceeds the threshold. Simply stopping the machine or continuing to excavate is unreasonable and can easily lead to increased damage to the well wall or excessively low excavation efficiency. The goal is to balance safety protection and construction efficiency.

[0010] To address the dangerous situation where the displacement rate of the hydraulic cylinder of the support shoe continuously exceeds the threshold, and there is no systematic safety adjustment plan, relying solely on reducing force or stopping the machine cannot guarantee the anti-slip requirements, which can easily lead to the instability of the main unit, a reliable emergency protection system should be constructed.

[0011] When the maximum available anti-slip friction is insufficient, there is a lack of step-by-step decision-making logic, making it impossible to make up for the friction gap through optimization and adjustment. This can easily lead to direct interruption of tunneling, causing project delays, or forced tunneling, causing safety accidents. Therefore, risk classification and handling can be achieved.

[0012] To achieve these objectives and other advantages according to the present invention, a method for tunneling inclined shafts using a TBM with a steep gradient is provided, comprising the following steps:

[0013] Establish a benchmark for the excavation of a double-supported full-face tunnel boring machine under steep slope conditions. The steep slope conditions are the conditions for inclined shaft excavation where the angle between the axis of the inclined shaft and the horizontal plane is 15°-35°.

[0014] Start the tunneling machine and perform one tunneling advance stroke, with a stroke length of 300mm-800mm. At the same time, continuously monitor the first real-time tension force applied to the well wall by the first main support shoe group and the second real-time tension force applied to the well wall by the second main support shoe group.

[0015] Based on the preset total weight of the tunneling machine main unit and the real-time tunneling inclination angle, the downward force component is calculated using mechanical formulas, and the downward force component of the tunneling machine main unit's gravity along the inclined shaft axis is calculated in real time. Using the resistance to this downward force as the control objective, based on this downward force component, the preset safety margin, and the friction coefficient between the shaft wall and the support shoes, the target value of the second real-time support force required by the second main support shoe group is calculated. Using this second real-time support force target value as a constraint, combined with the preset effective tunneling thrust range of the cutterhead, the first real-time support force of the first main support shoe group and the total thrust of the tunneling machine's propulsion hydraulic cylinder are calculated. Based on the calculation results, the second real-time support force, the first real-time support force, and the total thrust of the propulsion hydraulic cylinder are dynamically set synchronously. The safety margin is a preset additional friction force value, which is between 50 kN and 300 kN.

[0016] Once the tunneling of this stroke is completed, the advance is stopped and the first and second main support shoe groups are kept in a taut state. The return hydraulic cylinder of the tunneling machine is activated, causing the main body of the tunneling machine to move forward one stroke along the axis of the inclined shaft. During the forward movement, the current value of the drive motor of the screw conveyor in the tunneling machine is monitored in real time. The real-time signal of the drive motor current value is used as a feedforward control variable and input to the control system corresponding to the continuous belt conveyor set behind the tunneling machine. According to a predetermined proportional coefficient, the running linear speed of the continuous belt conveyor is kept in a real-time proportional relationship with the current value of the drive motor. This proportional coefficient is between 0.01m / (s·A) and 0.05m / (s·A).

[0017] Preferably, during the step of activating the return hydraulic cylinder to move the main body of the tunneling machine forward by one stroke, the linear speed of the continuous belt conveyor behind the tunneling machine is controlled as follows:

[0018] The current value of the drive motor of the screw conveyor is used as the main adjustment signal, and the torque value of the drive roller of the continuous belt conveyor is collected in real time as the feedback correction signal.

[0019] The control system of the continuous belt conveyor first calculates the initial target linear velocity based on the current value of the drive motor and a predetermined proportional coefficient. At the same time, based on the initial target linear velocity and a preset load-speed model, the control system calculates the expected torque range corresponding to the expected flow rate of excavated soil at that linear velocity. The load-speed model is preset according to the tunneling parameters and the characteristics of the excavated soil.

[0020] The real-time torque value of the drive roller is compared with the expected torque range: if the real-time torque value is consistently higher than the upper limit of the expected torque range, and this state lasts for more than a first set duration, the control system determines that the actual load of the continuous belt conveyor is greater than the expected load, and adds a positive speed compensation amount to the initial target linear speed. The magnitude of the positive speed compensation amount is proportional to the extent to which the real-time torque value exceeds the upper limit of the expected torque range; if the real-time torque value is consistently lower than the lower limit of the expected torque range, and this state lasts for more than a second set duration, the control system determines that the actual load is less than expected or there is a risk of slippage, and controls the continuous belt conveyor to perform a deceleration process. During the deceleration process, the real-time torque value of the drive roller is continuously monitored, and it is determined whether it has recovered to the expected torque range; if it has recovered, the deceleration process is terminated and the current operating linear speed is maintained. The deceleration rate during the deceleration process is lower than the preset maximum value.

[0021] Preferably, when comparing the real-time torque value of the drive roller with the expected torque range, if the real-time torque value continuously deviates from the expected torque range, the following operating condition mode determination is performed:

[0022] The effective value change rate of the current of the screw conveyor drive motor and the speed following error of the continuous belt conveyor drive motor are calculated simultaneously.

[0023] Based on the following quantitative criteria, the mode for real-time identification of abnormal operating conditions is as follows:

[0024] When the short-term change rate of the real-time torque value is lower than the first threshold and the change rate of the effective current value is lower than the second threshold, it is determined to be a stable change mode of the actual load.

[0025] If the real-time torque value shows a positive peak exceeding the third threshold within the preset time window, and the speed following error shows an instantaneous deviation exceeding the fourth threshold within the associated time window where this peak occurs, it is judged as a large material or mechanical instantaneous jamming mode.

[0026] When the real-time torque value remains above the upper limit of the expected torque range for a duration that reaches the fifth threshold, and the average value within its rolling time window shows a monotonically increasing trend, it is identified as a continuous overload mode.

[0027] Preferably, based on the identified operating mode, the corresponding control strategy is switched and executed in real time:

[0028] If the actual load is determined to be in a stable change mode, then speed compensation or deceleration based on torque feedback is executed.

[0029] If the system is identified as a large piece of material or a momentary mechanical jamming mode, the current speed-based control command is immediately interrupted, and the continuous belt conveyor is controlled to limit and stabilize the output torque of its drive motor at a preset safe torque threshold for a first preset duration. After the first preset duration ends, the torque limiting state is exited, and the closed-loop control of the continuous belt conveyor's running linear speed is restored based on the drive motor current value of the screw conveyor.

[0030] If the system is determined to be in a continuous overload mode, a load reduction operation procedure is initiated. This procedure includes: gradually reducing the target linear velocity by a preset decreasing step size based on the proportion by which the real-time torque value exceeds the upper limit of the expected torque range, until the real-time torque value returns to the expected torque range.

[0031] Preferably, the step of starting the tunneling machine and executing one tunneling propulsion stroke further includes real-time monitoring and dynamic early warning settings for the bearing condition of the well wall, specifically:

[0032] Real-time monitoring of the extension displacement rate of each support shoe cylinder in the first and second main support shoe groups;

[0033] Based on the assessment information of the rock mass stability ahead of the current tunneling section, and the correspondence between the pressure and displacement change rate of each support shoe cylinder recorded in the stable wellbore section during historical tunneling, a warning threshold for the displacement change rate is dynamically set for each support shoe cylinder.

[0034] Preferably, when the displacement change rate of any support shoe cylinder exceeds its warning threshold, the control system immediately executes primary control and graded judgment, specifically as follows:

[0035] S1. Control the abnormal support shoe cylinder to reduce the tension force to a preset initial low value;

[0036] S2. Simultaneously reduce the total thrust of the hydraulic cylinder by a preset percentage;

[0037] S3. Within the first set time window after executing steps S1 and S2, continuously monitor the displacement change rate of the abnormal support shoe cylinder and make a graded judgment accordingly:

[0038] If the displacement change rate has dropped below its warning threshold before the end of the first time window, a controlled state determination is made: if the displacement change rate drops by more than a preset proportion of its initial excess, it is determined to be a first type of response condition. At this time, the control system restores the tensioning force of the abnormal support shoe cylinder to the value before it executes step S1, and adjusts the total thrust to the value before it executes step S2, and continues the current stroke tunneling.

[0039] If the rate of displacement change drops below the warning threshold within the first time window, and the rate of decrease does not exceed the preset ratio, it is determined to be a second type of response condition; the control system maintains the tension of the abnormal support shoe cylinder at the initial low value and maintains the reduced total thrust to complete the tunneling.

[0040] If the rate of displacement change is still higher than its warning threshold at the end of the first time window, it is determined to be a third type of response condition and triggers systemic safety adjustment control.

[0041] Preferably, when the response condition is determined to be a Type III condition and a systemic safety adjustment control is triggered, the control system executes the following steps:

[0042] Maintain the abnormal support shoe low tension force set in step S1 and the total thrust set in step S2, while continuously monitoring the pressure and displacement change rate of all support shoe cylinders; when the fluctuation amplitude of the pressure and displacement change rate is continuously lower than their respective preset stability thresholds, it is determined that the current working condition has entered a stable state.

[0043] After determining that the current working condition has entered a stable state, evaluate the average pressure and average displacement rate of the other normal support shoe cylinders in the main support shoe group to which the abnormal support shoe cylinder belongs.

[0044] While maintaining the current reduced total thrust level, recalculate the total clamping friction force required to resist the sliding component force, and calculate the actual total friction force that all support shoe cylinders can provide at present based on the real-time working pressure of each support shoe cylinder.

[0045] Calculate the friction gap value, which is the difference between the total required tension friction force and the actual total friction force. The friction gap value is compensated by increasing the overall tension force of another main support shoe group. During the process of increasing the tension force, the displacement change rate of all support shoe cylinders in this group is monitored in real time.

[0046] If, during the process of increasing the tension, the displacement rate of any support shoe cylinder in the other main support shoe group exceeds its warning threshold, the increase of the tension of that group shall be stopped immediately, and the total friction force provided by the support shoe cylinders of that group at this time shall be recorded as the maximum available anti-slip friction force under the current working condition.

[0047] Preferably, the final operating condition decision is based on the recorded maximum available anti-slip friction:

[0048] If the maximum available anti-slip friction force is greater than or equal to the total tightening friction force requirement, the system is determined to be able to work stably under the current working conditions and maintain the current parameters to complete this tunneling stroke.

[0049] If the maximum available anti-slip friction force is less than the total tension friction force requirement, the system is deemed to have insufficient anti-slip capability and an early warning is issued. The control system first optimizes the tension force on the other normal support shoe cylinders in the main support shoe group to which the abnormal support shoe cylinder belongs, on the premise that the displacement change rate of each support shoe cylinder does not exceed its early warning threshold. The principle of internal optimization is that the displacement change rate of each normal support shoe cylinder does not exceed its early warning threshold and the tension force is evenly distributed.

[0050] If, after internal optimization, the total friction of the system cannot meet the total clamping friction requirement, the total thrust will be gradually reduced to the minimum preset value, and the total clamping friction requirement will be recalculated after each reduction in thrust.

[0051] If the total thrust reaches the minimum preset value and the recalculated total clamping friction requirement is greater than the maximum available anti-slip friction, the current tunneling process will be unconditionally interrupted and a wellbore instability handling alarm will be triggered.

[0052] The present invention has at least the following beneficial effects:

[0053] This invention achieves dynamic and precise matching of the TBM's clamping force, propulsion force, and sliding force under steep inclines. It enhances anti-slip reliability through a safety margin design and simultaneously controls the speed of the excavated soil conveyor line to prevent accumulation or slippage. This invention effectively solves the risk of main unit instability, protects the shaft wall from excessive compression, balances tunneling safety and efficiency, is suitable for 15°-35° inclined shaft conditions, eliminates the need for manual parameter adjustments based on experience, reduces operational difficulty, and ensures construction continuity.

[0054] This invention employs a dual-signal control mode of current feedforward + torque feedback, combined with a load-speed model to accurately predict the torque range, thereby achieving dynamic correction of the belt conveyor's linear speed. This invention can adjust the speed according to the real-time load, avoiding the lag of single-signal control, reducing problems such as soil accumulation, equipment overload, or slippage, improving the stability of soil conveying, adapting to varying soil output on steep slopes, and ensuring smooth tunneling cycles.

[0055] This invention constructs a working condition discrimination system through multiple quantitative indicators, enabling precise differentiation of different abnormal working conditions and overcoming the shortcomings of traditional discrimination methods that are vague and subjective. This invention provides a clear basis for subsequent targeted handling, avoiding the need to apply uniform measures to different faults such as momentary jamming and continuous overload, reducing ineffective equipment losses, lowering the risk of fault escalation, and improving the intelligent level of belt conveyor operation.

[0056] This invention provides customized control strategies for different abnormal operating conditions. It limits torque to prevent damage during momentary jamming, stabilizes the load through step-down speed reduction during sustained overload, and precisely compensates for speed changes when the load is stable. This invention ensures that all types of faults are handled scientifically, balancing equipment protection and continuous transport, avoiding tunneling interruptions due to improper handling, guaranteeing the efficiency of steep slope TBM construction, and extending equipment lifespan.

[0057] This invention expands the monitoring dimension to include the displacement change rate of the hydraulic cylinder of the support shoe, and dynamically sets early warning thresholds by combining geological assessment and historical data to adapt to different rock mass conditions. This invention can predict abnormal wellbore bearing capacity in advance, avoiding missed risks caused by monitoring only the support force. It can issue early warnings before potential damage to the wellbore occurs, reducing wellbore failure, lowering subsequent repair costs, and ensuring tunneling safety.

[0058] This invention establishes a hierarchical control and judgment mechanism. Upon exceeding a threshold, primary stress reduction protection is first implemented, followed by differentiated handling based on the recovery status. This invention avoids the drawbacks of blindly shutting down or continuing tunneling. During rapid recovery, parameters are promptly reset to ensure efficiency; during slow recovery, low load is maintained for safety; and in dangerous conditions, emergency adjustments are triggered, balancing safety protection and construction progress, and improving adaptability to different working conditions.

[0059] This invention provides a systematic adjustment scheme for hazardous working conditions. It achieves dynamic balance of anti-slip force through working condition stability assessment and friction gap compensation, while cross-group compensation and tightening force ensure anti-slip requirements are met. This invention avoids main engine instability caused by a single force reduction, while simultaneously monitoring the status of another set of support shoes in real time to prevent secondary damage to the wellbore, constructing a reliable emergency protection system, and improving the fault tolerance and safety of steep-slope tunneling.

[0060] This invention establishes a tiered decision-making logic, prioritizing internal optimization and thrust reduction to compensate for friction gaps, and only interrupting tunneling when necessary, thereby minimizing project delays. This invention clearly defines handling paths for different risk levels, avoiding both safety accidents caused by forced tunneling and inefficiency due to excessive conservatism, while issuing precise early warnings to guide on-site handling and ensure the controllability and safety of steep-slope tunneling.

[0061] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0062] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0063] According to one embodiment of the present invention, a TBM tunneling method for steep inclined shafts includes the following steps:

[0064] Establish a benchmark for the excavation of a double-supported full-face tunnel boring machine (TBM) under steep slope conditions. A steep slope condition is defined as an inclined shaft excavation where the angle between the shaft axis and the horizontal plane is 15°-35°. The steep slope can be any angle among 15°, 20°, 25°, 30°, and 35°. A double-supported hard rock TBM can be used as the excavation equipment. The main body material can be high-strength alloy steel, and the support shoe assembly material can be high-strength wear-resistant alloy steel. The TBM can be installed at the starting position of the inclined shaft, with the machine body axis aligned with the inclined shaft axis. When establishing the excavation benchmark, first calibrate the inclined shaft axis angle using an inclination sensor, then adjust the position of the support shoe assembly to initially fit against the shaft wall, ensuring the excavation direction is consistent with the inclined shaft axis. Parameter setting can be done by pre-setting benchmark values ​​based on the slope parameters in the inclined shaft design drawings, and then calibrating with the aid of a level and laser positioning instrument.

[0065] The tunneling machine is started and a tunneling propulsion stroke is executed, with a stroke length of 300mm-800mm. Simultaneously, the first real-time tension force applied to the shaft wall by the first main support shoe group and the second real-time tension force applied to the shaft wall by the second main support shoe group are continuously monitored. The stroke length can be any value among 300mm, 500mm, 600mm, and 800mm. A hydraulic propulsion system can be used as the propulsion device, and the propulsion hydraulic cylinder can be made of 45# steel. Pressure sensors can be used to monitor the tension force; the pressure sensor housing can be made of stainless steel, and the accuracy class can be set to 0.5. The hydraulic propulsion system can be mounted at the rear of the tunneling machine main unit and fixedly connected to the machine frame. The pressure sensor can be mounted in the hydraulic circuit of each support shoe cylinder in the first and second main support shoe groups, collecting the hydraulic pressure in real time and converting it into tension force data. During operation, the hydraulic propulsion system is started, driving the cutterhead to rotate and cut the rock, while simultaneously propelling the machine body forward a set stroke. The pressure sensor synchronously collects the first real-time tension force of the first main support shoe group and the second real-time tension force of the second main support shoe group, and the data is transmitted to the control system.

[0066] Based on the preset total weight of the tunneling machine (TBM) and the real-time tunneling inclination angle, the sliding component force is calculated using mechanical formulas (specifically, sliding component force = machine weight × sin(tunneling inclination angle)). The sliding component force of the TBM's weight along the inclined shaft axis is calculated in real-time. An inclination sensor can be used to collect the real-time tunneling inclination angle. The inclination sensor can be mounted in the middle of the TBM's body and rigidly connected to it. The measurement range covers 0°-90°, with a measurement accuracy of ±0.1°. The machine weight can be preset using factory parameters. The inclination sensor transmits inclination angle data to the control system in real-time, and the control system automatically substitutes it into the formula to calculate the sliding component force, updating the calculation results every 100ms. The safety margin can be selected from any value among 50kN, 100kN, 200kN, and 300kN. The friction coefficient between the shaft wall and the support shoe can be set according to the shaft wall rock type; it can be set to 0.3-0.5 for hard rock conditions and 0.2-0.3 for soft rock conditions. The friction coefficient can be set by taking samples during preliminary geological exploration, testing the friction coefficient between the rock samples and the support shoe material using a friction and wear testing machine, and taking the median value of the test results as the preset value. During operation, the control system first substitutes the sliding force, safety margin, and friction coefficient, and calculates the second real-time support force target value through a formula to ensure that the friction force generated between the support shoe and the well wall is sufficient to resist the sliding force.

[0067] With the control objective of resisting the downward force, the target value of the second real-time support force required by the second main support shoe group is calculated based on the downward force, the preset safety margin, and the friction coefficient between the well wall and the support shoe.

[0068] Using the second real-time tension target value as a constraint, and combined with the preset effective tunneling thrust range of the cutterhead, the first real-time tension of the first main support shoe assembly and the total thrust of the tunneling machine's propulsion hydraulic cylinders are calculated. The effective tunneling thrust range of the cutterhead can be set to 1000kN-5000kN, with the specific value adjusted according to the cutterhead diameter and rock hardness. For hard rock conditions, it is taken as 3000kN-5000kN, and for soft rock conditions, it is taken as 1000kN-3000kN. A thrust sensor can be used to monitor the total thrust of the propulsion hydraulic cylinders. The thrust sensor can be mounted on the end of the cylinder rod of the propulsion hydraulic cylinder and connected to the cylinder rod and the machine frame. During operation, the control system, constrained by the second real-time tension target value, calculates the first real-time tension and the total thrust of the propulsion hydraulic cylinders within the effective tunneling thrust range of the cutterhead using mechanical balance formulas to ensure that the thrust and tension are matched.

[0069] Based on the calculation results, the second real-time tensioning force, the first real-time tensioning force, and the total thrust of the propulsion hydraulic cylinder are synchronously and dynamically set. The safety margin is a preset additional friction force value, ranging from 50kN to 300kN. An electro-hydraulic proportional valve can be used to control the pressure of the support shoe cylinder and the propulsion hydraulic cylinder. This valve can be installed on the main oil line of the hydraulic system and connected to the control system signal. During operation, the control system converts the calculated tensioning force and thrust values ​​into electrical signals, which are transmitted to the electro-hydraulic proportional valve. By adjusting the valve opening, the oil line pressure is controlled, achieving synchronous dynamic adjustment of the tensioning force and thrust. Parameters are adjusted every 200ms to ensure real-time matching with operating conditions.

[0070] After the tunneling stroke is completed, the advance is stopped while the first and second main support shoe assemblies remain taut. The return hydraulic cylinder of the tunneling machine is activated, causing the main body of the tunneling machine to move forward one stroke along the axis of the inclined shaft. During this forward movement, the current value of the drive motor of the screw conveyor in the tunneling machine is monitored in real time. The real-time signal of the drive motor current value is used as a feedforward control variable and input to the control system corresponding to the continuous belt conveyor located behind the tunneling machine. According to a predetermined proportional coefficient, the running linear speed of the continuous belt conveyor is kept in a real-time proportional relationship with the current value of the drive motor. This proportional coefficient is between 0.01 m / (s·A) and 0.05 m / (s·A). The return hydraulic cylinder can be made of 45# steel and has the same structure as the advance hydraulic cylinder. The return hydraulic cylinder can be mounted between the main body of the tunneling machine and the rear frame, with both ends hinged to the machine body and the frame, respectively. During operation, after the stroke is completed, the hydraulic propulsion system stops working, and the electro-hydraulic proportional valve maintains its current opening, keeping the support shoe assembly continuously taut. Then, the return hydraulic cylinder is activated, and its extension and retraction drive the main unit forward, the forward distance matching the propulsion stroke. During this forward movement, the support shoe assembly remains in contact with the shaft wall to prevent the main unit from sliding down. A current sensor can be used to monitor the drive motor current value. The current sensor can be mounted on the power supply line of the screw conveyor drive motor and connected to the control system signal. The screw conveyor can be mounted inside the tunneling machine main unit near the cutterhead, while the continuous belt conveyor can be mounted on one side of the inclined shaft roadway behind the tunneling machine main unit, with the machine body fixedly connected to the support at the bottom of the roadway. During operation, the current sensor collects the drive motor current data in real time and transmits it to the control system as a feedforward signal to adjust the operating status of the continuous belt conveyor. The proportionality coefficient can be selected from any value among 0.01m / (s·A), 0.02m / (s·A), 0.03m / (s·A), 0.04m / (s·A), and 0.05m / (s·A). For soft rock conditions, use 0.03m / (s·A)–0.05m / (s·A), and for hard rock conditions, use 0.01m / (s·A)–0.03m / (s·A). (In soft rock formations, the cutterhead excavation resistance is relatively small, and under the same current, the amount of excavated and discharged excavated soil per unit time is usually greater, and the excavated soil is often more viscous.) Due to the tendency of soil to stick, a higher linear speed of the belt conveyor is required to prevent soil accumulation within the conveying system. Therefore, a relatively large proportional coefficient of 0.03-0.05 m / (s·A) is set to achieve a higher current-speed gain and ensure sufficient conveying capacity. Conversely, in hard rock conditions, the soil yield is lower and the particle size is more uniform. Excessive linear speed can easily lead to insufficient conveyor belt load or soil spillage. Therefore, a lower proportional coefficient of 0.01-0.03 m / (s·A) is used to make the speed adjustment smoother, balancing conveying efficiency and stability.A variable frequency drive (VFD) controller can be used to control the linear speed of the continuous belt conveyor. The VFD controller can be installed inside the electrical control cabinet of the continuous belt conveyor and connected to the drive motor and control system. During operation, the control system calculates the target linear speed of the continuous belt conveyor based on the current sensor signal and a preset proportional coefficient. The VFD controller then adjusts the speed of the drive motor to achieve a direct proportional linkage between the linear speed and the current value, ensuring that the amount of slag conveyed matches the output.

[0071] The correlation between the screw conveyor drive motor current and the amount of excavated soil produced is based on the excavated soil conveying volume corresponding to different current values ​​collected through preliminary tests. The fluctuation range of excavated soil production corresponding to each 1A change in current is determined, serving as the basis for feedforward control. The correspondence between the opening degree and pressure of the electro-hydraulic proportional valve can be determined through a preset calibration curve. The calibration curve collects corresponding pressure values ​​at 5% opening intervals, fitting a linear correlation equation to ensure precise matching between opening adjustment and target pressure. When calculating the tensioning force of the first main support shoe group and the total thrust of the propulsion hydraulic cylinder, the control system is based on the force balance relationship of the tunneling machine's main unit along the inclined shaft axis. The core of this mechanical balance is that the total thrust generated by the propulsion hydraulic cylinder must be equal to the thrust required for cutterhead excavation, the main unit's downward sliding force, and the sum of frictional losses within the system. Simultaneously, the total anti-slip friction force jointly provided by the first and second main support shoe groups must not be less than the sum of the main unit's downward sliding force and a preset safety margin to ensure no risk of the main unit sliding down. The calculation logic of the control system is as follows: First, the minimum target value of the support force required by the second main support shoe group is determined by using the anti-slip requirement as a mandatory constraint; then, under the premise of satisfying this constraint and the effective tunneling thrust range of the cutterhead, the reasonable values ​​of the support force of the first main support shoe group and the total thrust of the propulsion are solved.

[0072] By adopting this technical solution, the present invention ensures stable tunneling of the dual-support TBM in inclined shafts with a steep slope of 15°-35°, effectively resisting the downward force of the main unit's gravity and preventing the main unit from becoming unstable and sliding down; dynamically matching the clamping force, thrust, and downward force to protect the shaft wall from excessive compression damage, while ensuring that the cutterhead tunneling thrust is within an effective range and maintaining tunneling efficiency; realizing real-time linkage between the excavated soil conveying linear speed and the screw conveyor drive motor current to avoid excavated soil accumulation or insufficient conveying, ensuring the continuity of the tunneling cycle; and comprehensively improving the safety and stability of TBM tunneling in steep inclined shafts, adapting to the needs of different rock conditions.

[0073] According to another embodiment of the present invention, in the step of activating the return hydraulic cylinder to move the main body of the tunneling machine forward by one stroke, the running linear speed of the continuous belt conveyor behind the tunneling machine is controlled in the following manner:

[0074] The current value of the drive motor of the screw conveyor is used as the main control signal, and the torque value of the drive roller of the continuous belt conveyor is collected in real time as the feedback correction signal. A torque sensor can be selected to collect the torque value of the drive roller. The torque sensor can be mounted on the end of the shaft of the drive roller of the continuous belt conveyor, connected to the shaft and the frame. The measurement range is 0 N·m-5000 N·m, and the measurement accuracy is ±5 N·m. During operation, the current signal collected by the current sensor is used as the main control signal, and the torque sensor synchronously collects the real-time torque value of the drive roller, transmitting it to the control system as a feedback signal to form a closed-loop control.

[0075] The control system of the continuous belt conveyor first calculates the initial target linear velocity based on the drive motor current value using a predetermined proportional coefficient. Simultaneously, based on the initial target linear velocity and a pre-set load-velocity model, the control system calculates the expected torque range corresponding to the expected flow rate of excavated soil at that linear velocity. This load-velocity model is pre-set based on tunneling parameters and excavated soil characteristics. The load-velocity model is pre-established through analysis and learning of historical tunneling data (pre-set tunneling parameters and excavated soil characteristics, including particle size and moisture content, with particle size ranging from 0mm to 200mm and moisture content from 5% to 20%). Specifically, during stable tunneling stages with various typical rock formations and combinations of tunneling parameters, the system synchronously records the screw conveyor drive motor current, the continuous belt conveyor's operating linear velocity, the drive roller torque, and relevant excavated soil characteristics (such as average particle size and moisture content) and tunneling parameters (such as cutterhead rotation speed). Using this data, through multiple regression analysis or machine learning algorithms, the system fits the correspondence between the conveyor linear velocity and the expected drive torque under different operating conditions. Based on this model, for any given current linear velocity, the system can predict a normal driving torque value and its reasonable fluctuation range (i.e., the expected torque range). During operation, the control system first substitutes the current value and proportional coefficient to calculate the initial target linear velocity, and then obtains the corresponding expected torque range through the load-speed model. The upper and lower limits of the expected torque range are set at 500 N·m (the basis for setting the upper and lower limits of the expected torque range at 500 N·m is determined by combining 10%-15% of the rated torque of the belt conveyor, ensuring that the difference adapts to load fluctuations while avoiding frequent adjustments). The load-speed model is preset according to the tunneling parameters and the characteristics of the excavated soil. The tunneling parameters include tunneling speed and cutterhead speed. The cutterhead speed can be set from 5 r / min to 20 r / min, and the tunneling speed can be set from 5 mm / min to 30 mm / min. The experimental objects for model establishment were the continuous belt conveyor and the screw conveyor. The experimental method simulated different combinations of slag and tunneling parameters, collecting corresponding linear velocity and torque values. Statistical analysis employed linear regression to fit the data, forming a load-velocity model. The model error was controlled within a preset range. The specific fitting form of the load-velocity model used a linear fitting function V = k × T + b, where V is the linear velocity of the belt conveyor, T is the torque of the drive roller, k is the fitting slope, and b is the intercept. This model was derived by fitting data from at least 30 sets of data under different working conditions, with a fitting accuracy R0. 2 Not less than 0.95. Regarding materials, the conveyor belt of a continuous belt conveyor can be made of rubber canvas, and the drive roller can be made of high-strength alloy steel.

[0076] The real-time torque value of the drive roller is compared with the expected torque range: if the real-time torque value is consistently higher than the upper limit of the expected torque range, and this state lasts for more than a first set duration, the control system determines that the actual load of the continuous belt conveyor is greater than the expected load, and adds a positive speed compensation amount to the initial target linear speed. The magnitude of the positive speed compensation amount is proportional to the extent to which the real-time torque value exceeds the upper limit of the expected torque range; if the real-time torque value is consistently lower than the lower limit of the expected torque range, and this state lasts for more than a second set duration, the control system determines that the actual load is less than expected or there is a risk of slippage, and controls the continuous belt conveyor to perform a deceleration process. During the deceleration process, the real-time torque value of the drive roller is continuously monitored, and it is determined whether it has recovered to the expected torque range; if it has recovered, the deceleration process is terminated and the current operating linear speed is maintained. The deceleration rate during the deceleration process is lower than the preset maximum value. The first set duration can be set to 3 seconds, and the second set duration can be set to 2 seconds. The magnitude of the positive speed compensation is proportional to the extent to which the real-time torque value exceeds the upper limit of the expected torque range. The compensation coefficient is set to 0.005 m / (s·N·m). For example, the greater the torque exceedance, the greater the speed compensation. This positive compensation aims to alleviate overload by increasing the conveying speed. The proportional relationship (compensation coefficient) can be determined based on system characteristics and experience. During operation, the control system compares the real-time torque value with the expected torque range in real time. If the real-time torque value remains above the upper limit for 3 seconds, the positive speed compensation is calculated according to the compensation coefficient and added to the initial target linear speed to increase the belt conveyor's operating speed and reduce slag accumulation. If the real-time torque value remains below the lower limit for 2 seconds, it is determined to be underloaded or slipping, and the deceleration process is initiated. The deceleration rate during the deceleration process is set to 0.02 m / s². 2 The preset maximum value is 0.05 m / s 2 To ensure smooth deceleration and prevent soil slippage, a speed sensor can be used to monitor the linear speed of the belt conveyor. The speed sensor can be mounted on the driven roller end of the continuous belt conveyor and connected to it, providing real-time feedback of the operating speed to the control system. The correction logic for the speed sensor feedback signal uses a PID algorithm to correct the deceleration, with a proportional coefficient set to 0.5, an integral time set to 0.1s, and a derivative time set to 0.05s, ensuring that the deceleration remains stable within the preset range. During operation, the control system gradually reduces the drive motor speed through the frequency converter during deceleration. The speed sensor provides real-time feedback on speed changes to ensure that the deceleration does not exceed the maximum value. If the torque value recovers to the expected range, deceleration is immediately terminated, maintaining the current linear speed.

[0077] This invention improves the linear speed control accuracy of continuous belt conveyors through closed-loop control of current feedforward and torque feedback, avoiding the lag caused by single signal control; it predicts the torque range based on the load-speed model, making the linear speed adjustment more in line with the actual needs of muck transportation; it adopts differentiated speed adjustment strategies for abnormal torque conditions, reducing muck accumulation, equipment overload or slippage, and ensuring the stability of muck transportation; the deceleration process is smooth and controllable, avoiding safety hazards caused by muck slippage on steep slopes, and is suitable for muck transportation conditions in steep inclined shaft excavation.

[0078] According to another embodiment of the present invention, when comparing the real-time torque value of the drive roller with the expected torque range, if the real-time torque value continuously deviates from the expected torque range, the following operating condition mode determination is performed:

[0079] The effective rate of change of the current of the screw conveyor drive motor and the speed following error of the continuous belt conveyor drive motor are calculated synchronously. The calculation period for the effective rate of change of the current is set to 1 second, and the speed following error is the difference between the target speed and the actual speed, with an error threshold of ±5 r / min. An oscilloscope can be used to acquire the motor current signal. The oscilloscope can be connected to the output of the current sensor (the data transmission method between the oscilloscope, data acquisition unit, and control system uses RS485 bus transmission, with a transmission baud rate set to 9600 bps to ensure real-time data transmission with a delay of no more than 100 ms) for analyzing the effective rate of change of the current. The speed sensor can be mounted on the output shaft of the continuous belt conveyor drive motor to acquire actual speed data. The effective rate of change of the current is calculated as the difference between the maximum and minimum effective values ​​of the current within 1 second, and the short-time torque change rate is calculated as the change of the arithmetic mean of the instantaneous torque values ​​within 0.5 seconds.

[0080] Based on the following quantitative criteria, the mode for real-time identification of abnormal operating conditions is as follows:

[0081] When the short-term rate of change of the real-time torque value is lower than the first threshold and the effective rate of change of the current value is lower than the second threshold, the system is identified as being in a stable load change mode. The first threshold is set to 0.5 N·m / s, and the second threshold is set to 0.3 A / s. That is, when the short-term rate of change of the real-time torque value is lower than 0.5 N·m / s and the effective rate of change of the current value is lower than 0.3 A / s, the system is identified as being in a stable load change mode. (The thresholds for the short-term torque rate of change and the current rate of change used to identify the stable change mode are determined through statistical analysis of a large amount of data from normal and stable operating periods. For example, a threshold value that is not exceeded in more than 95% of stable data periods can be used.) The calculation period for the short-term rate of change is set to 0.5 s. During operation, the control system calculates the short-term torque rate of change every 0.5 s and the effective rate of change of the current value every 1 s, compares them with the set thresholds, and completes the operating condition identification.

[0082] If the real-time torque value exhibits a positive peak exceeding the third threshold within a preset time window, and the speed following error shows an instantaneous deviation exceeding the fourth threshold within the associated time window of this peak, it is identified as a large material or mechanical momentary jamming mode. The third threshold is set to 1000 N·m, the fourth threshold is set to 10 r / min, the preset time window is set to 0.5 s, and the associated time window is set to 1 s. That is, if the real-time torque value exhibits a positive peak exceeding 1000 N·m within 0.5 s, and the speed following error shows an instantaneous deviation exceeding 10 r / min within the 1 s associated time window of this peak, it is considered a momentary jamming mode caused by large materials or mechanical momentary jamming. (The speed following error threshold used for distinguishing the same mode takes into account the dynamic response characteristics of the drive motor control system and is usually several times the normal control overshoot. The duration threshold (e.g., 5 seconds) used for distinguishing the "continuous overload mode" is related to the thermal inertia and allowable short-term overload capacity of the drive system, aiming to distinguish between instantaneous impact and continuous overload that may trigger thermal protection.) It is distinguished as a large material or mechanical instantaneous jamming mode; the torque positive peak threshold (e.g., 1000 N·m) used for distinguishing the instantaneous jamming mode is set based on the estimated impact torque value generated by the smallest typical rock block size that may cause jamming. During operation, the control system monitors the torque peak and speed following error in real time. When the above conditions are met within the set time window, it is immediately distinguished as the corresponding working condition, and the peak occurrence time and error value are recorded to provide a basis for subsequent handling.

[0083] If the real-time torque value remains above the upper limit of the expected torque range for a duration exceeding the fifth threshold, and the mean value within its rolling time window exhibits a monotonically increasing trend (the criterion for a monotonically increasing trend is to confirm that the overload condition is still worsening), then it is classified as a continuous overload mode. The fifth threshold is set to 5 seconds, and the rolling time window is set to 3 seconds. That is, if the real-time torque value remains above the upper limit of the expected torque range for 5 seconds, and the mean value within its 3-second rolling time window exhibits a monotonically increasing trend, it is classified as a continuous overload mode. The mean value within the rolling time window is calculated using the arithmetic mean method, with the mean data updated every 0.5 seconds. The control system compares adjacent mean data to determine whether there is a monotonically increasing trend (the criterion for a monotonically increasing mean value within the rolling time window is that the mean value of three consecutive updates increases sequentially, and the increase is not less than 0.5 N·m). A data acquisition device can be used to record the torque value and mean data. The data acquisition device can be installed at the signal output end of the control system, with a storage period set to 0.1 seconds for easy subsequent operating condition analysis.

[0084] By adopting this technical solution, the present invention achieves accurate differentiation of different abnormal working conditions through multi-dimensional quantitative criteria, avoiding the subjectivity and ambiguity of traditional discrimination methods; it clarifies the discrimination criteria for each working condition, providing a clear basis for subsequent targeted handling; it reduces the probability of misjudgment of working conditions, avoiding the expansion of equipment damage or failure caused by taking uniform handling measures for different abnormal working conditions; and it improves the intelligent level of continuous belt conveyor operation status monitoring, ensuring the stability of slag and soil transportation in steep inclined shafts.

[0085] According to another embodiment of the present invention, based on the identified operating mode, the corresponding control strategy is switched and executed in real time:

[0086] If the actual load is determined to be in a stable change mode, then a speed compensation or deceleration process based on torque feedback is executed; the speed compensation is adjusted according to the preset compensation coefficient, and the deceleration process is executed according to the preset deceleration, with the compensation coefficient and deceleration being consistent (the deceleration during the deceleration process is set to 0.02 m / s). 2 With the compensation coefficient set at 0.005 m / (s·N·m), there is no need to repeatedly adjust the equipment and parameters. During operation, after the control system identifies this mode, it directly calls the corresponding control logic and dynamically adjusts the linear speed based on the torque feedback signal to ensure that the speed matches the load and maintains stable conveying.

[0087] If a large piece of material or a momentary mechanical jamming mode is detected, the current speed-based control command is immediately interrupted. The continuous belt conveyor is controlled to limit and stabilize the output torque of its drive motor at a preset safe torque threshold for a first preset duration. After the first preset duration ends, the torque limiting state is exited, and closed-loop control of the continuous belt conveyor's linear speed is restored based on the drive motor current value of the screw conveyor. The first preset duration is set to 2 seconds. The safe torque threshold can be set to 2000 N·m, determined according to the rated torque of the belt conveyor, and should not exceed 60% of the rated torque. During operation, after the speed control command is interrupted, the control system limits the drive motor's output torque through the frequency converter, stabilizing it at 2000 N·m for 2 seconds to avoid momentary jamming causing motor overload or conveyor belt damage, while providing time for large pieces of material to pass or for the jamming to be cleared. During the recovery process, the linear speed gradually increases to the target linear speed corresponding to the current current value, with a recovery rate set to 0.03 m / s² (linear speed recovery rate 0.03 m / s²). 2The setting is based on the angle of repose test of the slag (this rate is lower than the critical recovery rate of slag sliding on the conveyor belt), to avoid slag slippage caused by sudden speed changes. During operation, after the preset time expires, the control system releases the torque limit, switches back to closed-loop control mode, adjusts the linear speed according to the current signal and torque feedback signal, gradually restores to normal operation, and continuously monitors the working condition to prevent jamming from happening again; the rated torque of the belt conveyor is determined by calculation based on the design conveying capacity, conveyor belt width, and slag bulk density, using the formula T. 额定 =K×Q×v×r, where K is the safety factor (taken as 1.2-1.5), Q is the conveying capacity, v is the linear velocity, and r is the radius of the drive roller;

[0088] If a continuous overload mode is detected, a load reduction operation procedure is initiated. This procedure includes: based on the proportion by which the real-time torque value exceeds the upper limit of the expected torque range, gradually reducing the target linear velocity with a preset decreasing step size until the real-time torque value recovers to the expected torque range. The decreasing step size is set to 0.02 m / s, and each decrease is held for 1 second. The torque value is then used to determine whether to continue reducing the speed. During operation, the control system calculates the torque excess ratio and gradually reduces the target linear velocity with the decreasing step size. After each adjustment, the torque change is monitored until the torque recovers to the expected range, at which point the speed reduction stops and the current linear velocity is maintained. The relationship between the torque excess ratio and the decreasing step size during load reduction is: Δv = 0.02 × (T 实际 -T 上限 ) / T 上限 Where Δv is the decreasing step size, T 实际 For real-time torque, T 上限 This represents the upper limit of the expected torque.

[0089] This invention provides targeted control strategies for different abnormal working conditions, achieving precise matching between working conditions and handling measures; limiting torque to protect equipment during momentary jamming to avoid overload damage, and delaying recovery to ensure continuous conveying; step-down speed reduction to smoothly reduce load during continuous overload to prevent the fault from escalating; precise speed adjustment to maintain conveying efficiency when the load changes steadily; and overall improvement of the fault handling capability of continuous belt conveyors to ensure the continuity and safety of inclined shaft excavation with large slopes.

[0090] According to another embodiment of the present invention, the step of starting the tunneling machine and performing one tunneling propulsion stroke further includes real-time monitoring and dynamic early warning settings for the bearing state of the well wall, specifically:

[0091] The system monitors the rate of change of extension displacement of each support shoe cylinder in the first and second main support shoe groups in real time. A displacement sensor can be used to monitor this rate of change. The displacement sensor can be mounted on the outside of the cylinder barrel and connected to the cylinder rod. The measurement range is 0mm-500mm, the measurement accuracy is ±0.1mm, and the calculation period for the rate of change of displacement is set to 0.5s. During operation, the displacement sensor collects the extension displacement data of each support shoe cylinder in real time. The control system calculates the rate of change every 0.5s and transmits the data synchronously to the monitoring terminal.

[0092] Based on the assessment information of the rock mass stability ahead of the current tunneling section, and the correspondence between the pressure and displacement change rate of each support shoe cylinder recorded in the stable wellbore section during historical tunneling (historical data fitting uses the least squares method, and the fitting accuracy requirement is R...), 2 To ensure the reliability of the correlation between pressure and displacement change rates (≥0.9), a dynamic warning threshold for the displacement change rate is set for each support shoe cylinder. Rock mass stability assessment can be achieved through ground-penetrating radar (GPR) detection data quantification standards: a detection wave velocity greater than 3000 m / s indicates intact rock mass, 1500-3000 m / s indicates relatively intact rock mass, and less than 1500 m / s indicates fractured rock mass). GPR can be mounted above the cutterhead of the tunneling machine and fixedly connected to the machine body, with a detection depth of 0-5m, used to obtain data on the integrity of the rock mass ahead. Historical data can be recorded through a data storage module, which can be installed inside the control system, storing historical support shoe pressure, displacement change rate, and corresponding wellbore condition data. The warning threshold is set according to the rock mass stability classification: 0.5 mm / s for intact rock mass, 0.3 mm / s for relatively intact rock mass, and 0.1 mm / s for fractured rock mass. The setting method is to automatically match the warning threshold by fitting the correspondence between pressure and displacement change rate through historical data and combining it with the current rock mass assessment results. The dynamic setting of the displacement change rate warning threshold is a process that integrates real-time geological assessment and historical experience data. In practice, the control system pre-stores baseline values ​​for warning thresholds corresponding to different rock mass stability levels (e.g., intact, relatively intact, broken), derived from theoretical calculations and engineering experience. Simultaneously, the system acquires real-time geological assessment information of the rock mass ahead (e.g., the Rock Mass Integrity Index (RQD) obtained through ground-penetrating radar) and converts it into the corresponding stability level. Furthermore, the system also calls upon the historical average displacement rate of each support shoe recorded during recent excavation in similarly stable rock strata. The final dynamic warning threshold is obtained through a weighted comprehensive calculation of the aforementioned theoretical baseline values ​​and historical experience values. For example, a higher weight can be assigned to the real-time geological assessment results, while fine-tuning can be made by referring to historical performance, so that the threshold reflects both current geological conditions and the actual operating characteristics of the equipment.

[0093] This invention expands the monitoring dimensions of wellbore bearing capacity, extending from single pressure monitoring to displacement change rate monitoring, enabling early prediction of potential wellbore damage risks; dynamic early warning thresholds are adapted to different rock mass stability conditions, avoiding inaccurate or missed warnings caused by fixed thresholds; thresholds are set based on historical data and real-time geological assessments, improving early warning reliability and reducing wellbore damage; and it provides accurate monitoring data for subsequent wellbore protection and control, ensuring wellbore safety during steep inclined shaft excavation.

[0094] According to another embodiment of the present invention, when the displacement change rate of any support shoe cylinder exceeds its warning threshold, the control system immediately performs primary control and graded judgment, specifically as follows:

[0095] S1. Control the abnormal support shoe cylinder's clamping force to decrease to a preset initial low value; the initial low value can be set to 500kN, determined according to the rated clamping force of the support shoe cylinder (the determination of the rated clamping force of the support shoe cylinder is based on the well wall rock mass compressive strength test and the calculation of the support shoe contact area to ensure that the rated clamping force does not exceed the well wall's ultimate bearing capacity), and is not less than 20% of the rated clamping force. During operation, after the control system detects an over-threshold signal, it immediately sends a signal to the corresponding electro-hydraulic proportional valve of the support shoe cylinder, adjusts the valve opening to reduce the oil circuit pressure, and reduces the clamping force to the initial low value, thereby reducing the pressure on the well wall;

[0096] S2. Simultaneously, reduce the total thrust of the propulsion hydraulic cylinder by a preset percentage; the preset percentage is set to 30% (the preset percentage is mainly to balance the needs of well wall protection and continuous tunneling. Reducing the thrust by a certain percentage aims to reduce disturbance to areas of suspected well wall instability, while ensuring that the remaining thrust can still maintain the minimum effective tunneling requirements of the cutterhead and avoid complete tunneling stagnation. The reason for setting the preset thrust reduction ratio of 30% is based on previous test data, which shows that this ratio can minimize well wall disturbance while maintaining the basic cutting capability of the cutterhead). The reduced thrust is not lower than the lower limit of the effective tunneling thrust range of the cutterhead. During operation, while reducing the tension of the abnormal support shoe cylinder, the control system synchronously adjusts the electro-hydraulic proportional valve of the propulsion hydraulic cylinder to reduce the total propulsion thrust by the preset percentage, reducing the disturbance of tunneling to the well wall, providing time for well wall stabilization, and maintaining the minimum effective tunneling capability of the cutterhead.

[0097] S3. Within the first set time window after executing steps S1 and S2, continuously monitor the displacement change rate of the abnormal support shoe cylinder and make a graded judgment accordingly (within the first set time window after executing primary control, continuously monitor the displacement change rate of the abnormal support shoe cylinder and make a graded judgment accordingly; the first set time window is set to 5 seconds, and the preset proportion of the initial portion exceeding the warning threshold is set to 80%). The preset proportion is used to scientifically assess the recoverability of wellbore deformation. This proportion is an empirical critical value used to judge the degree of recovery of the displacement rate after unloading. If the recovery exceeds this proportion, it is considered that the wellbore deformation is mainly elastic, the bearing capacity is basically recovered, and normal operation can be resumed; if the recovery is insufficient, it means that plastic deformation or damage has occurred, and protective measures need to be taken again.

[0098] If the displacement change rate has decreased to below its warning threshold before the end of the first time window, a controlled state determination is made: if the decrease in displacement change rate exceeds a preset proportion of its initial excess (exceeding the initial excess warning threshold), it is determined to be a first-type response condition. At this time, the control system restores the tensioning force of the abnormal support shoe cylinder to the value before its execution step S1 (tensioning force to the level before adjustment), and adjusts the total thrust to the value before its execution step S2, and continues the current stroke tunneling; during the recovery process, the tensioning force and thrust gradually rise, and the rise rate is set to 100kN / s (the critical basis for the rise rate of tensioning force and thrust of 100kN / s, this rate can avoid the support shoe from generating impact load on the well wall, and the rise time is controlled within 2s, which does not affect the tunneling efficiency), to avoid the condition fluctuation caused by parameter mutation. After recovery, the displacement change rate is continuously monitored to ensure no rebound; the first-type response condition mostly corresponds to the slight deformation of the well wall caused by instantaneous force disturbance, and the bearing capacity of the well wall is not substantially affected. Rapid parameter recovery can maximize the tunneling efficiency.

[0099] If the displacement change rate drops below the warning threshold within the first time window, and the decrease does not exceed a preset proportion, it is determined to be a second type of response condition. The control system maintains the clamping force of the abnormal support shoe cylinder at its initial low value and maintains the reduced total thrust to complete the tunneling. The second type of response condition indicates that the wellbore has minor damage or limited bearing capacity and cannot withstand the original parameter load. Maintaining low-load operation can prevent the damage from expanding and ensure the smooth completion of this stroke. During the operation, the current parameters are maintained to continue tunneling, while the displacement change rate monitoring is strengthened, and data is collected every 0.2 seconds until the stroke is completed to avoid secondary damage to the wellbore caused by parameter adjustments and to provide data support for parameter optimization in subsequent strokes.

[0100] If the rate of displacement change remains above the warning threshold at the end of the first time window, it is classified as a third-type response condition, triggering a systematic safety adjustment control. This third-type response condition is a high-risk scenario, meaning the wellbore's bearing capacity is nearing its limit. Simple primary control cannot solve the problem; a systematic adjustment is needed to balance anti-sliding requirements with wellbore protection to prevent main unit instability or wellbore collapse. During operation, if the rate of displacement change does not drop below the threshold after the time window ends, the control system classifies it as a dangerous condition, immediately sends a signal to trigger the systematic safety adjustment procedure, and simultaneously issues a warning signal to remind operators to pay attention to the condition and prepare for manual intervention. The first type of condition is common in hard rock with transient disturbances, the second type often occurs in soft rock or weathered rock sections, and the third type corresponds to fracture zones or precursors to local wellbore instability.

[0101] This technical solution enables rapid primary control upon exceeding a threshold, reducing wellbore compression and disturbance and preventing damage from escalating. Differential handling is achieved through tiered judgment: parameters are promptly reset to ensure tunneling efficiency during rapid recovery, while maintaining low load for safety during slow recovery; emergency adjustments are triggered promptly in dangerous conditions, constructing a multi-level wellbore protection mechanism; balancing wellbore safety and tunneling efficiency, adapting to different wellbore stability conditions, and enhancing the fault tolerance of steep-slope tunneling.

[0102] According to another embodiment of the present invention, when a third type of response condition is determined and a systemic safety adjustment control is triggered, the control system performs the following steps:

[0103] Maintain the abnormal low support force set in step S1 and the total thrust set in step S2, while continuously monitoring the pressure and displacement change rate of all support shoe cylinders. When the fluctuation amplitude of the pressure and displacement change rate is continuously lower than their respective preset stability thresholds, the current working condition is determined to have entered a stable state. The stability thresholds are set as follows: pressure fluctuation amplitude ±50kN, displacement change rate fluctuation amplitude ±0.05mm / s. The stability thresholds are set based on the accuracy of the pressure sensor (0.5 grade) and the displacement change rate threshold based on the sensor measurement accuracy and the minimum fluctuation value of the wellbore stability test. During operation, data from all support shoe cylinders are continuously collected through pressure and displacement sensors, updated every 0.1s, to determine whether the fluctuation amplitude is lower than the stability threshold. The duration is set to 2s, meaning that when the fluctuation amplitude is lower than the threshold and remains unchanged for 2s, the working condition is confirmed to be stable. During operation, the control system continuously monitors the fluctuation data. After the stability condition is met, it records the current pressure and displacement change rate data of all support shoe cylinders as the basis for subsequent calculations.

[0104] After determining that the current working condition has entered a stable state, the average pressure and average displacement change rate of the other normal support shoe cylinders in the main support shoe group to which the abnormal support shoe cylinder belongs are evaluated. The average pressure is calculated using the arithmetic mean method, and the average displacement change rate is also calculated using the arithmetic mean method. The calculation period is set to 1 second. During the operation, the control system extracts the data of the normal support shoe cylinders in the abnormal support shoe group, calculates the average value, and evaluates the working status of the support shoe group.

[0105] While maintaining the current reduced total thrust level, the required total clamping friction force to resist the sliding component is recalculated. Based on the real-time working pressure of each support shoe cylinder (the support shoe group to which the abnormal support shoe belongs), the actual total friction force that all support shoe cylinders (the support shoe group to which the abnormal support shoe belongs) can provide is calculated. The required total clamping friction force is obtained through the sliding component and safety margin. The actual total friction force is obtained through the pressure of each support shoe cylinder, the coefficient of friction, and the contact area of ​​the support shoe. The contact area of ​​the support shoe can be set to 0.5m. 2 -1.0m 2 The actual total friction force is calculated based on the basic formula of friction force, determined according to the size of the support shoe. The system multiplies the real-time working pressure of each support shoe cylinder by the effective working area of ​​its piston to obtain the normal pressure of the support shoe on the well wall. Then, the normal pressures of all support shoes are summed and multiplied by the preset friction coefficient to obtain the actual total anti-slip friction force that the current system can provide. The correspondence between the contact area of ​​the support shoe and the size of the support shoe is as follows: the area of ​​the circular support shoe is calculated according to S=πr², and the area of ​​the square support shoe is calculated according to S=a×b. The size selection is determined in combination with the flatness of the well wall and the stroke of the support shoe cylinder.

[0106] The friction gap value is calculated as the difference between the total required tensioning friction force and the actual total friction force. The friction gap value is compensated by increasing the overall tensioning force of another main support shoe group. During the increase of the tensioning force, the displacement change rate of all support shoe cylinders in this group is monitored in real time. During the compensation process, the tensioning force is gradually increased at a rate of 50 kN / s. Each time the parameter is increased, the displacement change rate of the support shoe cylinders in this group is monitored to ensure that it does not exceed their respective warning thresholds.

[0107] If, during the process of increasing the tension, the displacement rate of any cylinder in the other main support shoe group exceeds its warning threshold, the increase in tension for that group will be immediately stopped, and the total friction force provided by the cylinders in that group at this time will be recorded as the maximum available anti-slip friction force under the current working condition. During operation, upon detecting an over-threshold signal, the increase in tension will be immediately stopped, the current pressure will be maintained, and the maximum available anti-slip friction force data will be recorded to provide a basis for subsequent working condition decisions.

[0108] By adopting this technical solution, the present invention achieves systematic safety adjustment for dangerous working conditions. It first stabilizes the working conditions and then compensates for friction, avoiding instability caused by blind adjustment. It compensates for friction gaps across the main support shoe group to ensure the need to resist the sliding component force and prevent the main machine from sliding down. During the compensation process, the status of another set of support shoes is monitored in real time to avoid secondary damage to the well wall. It accurately records the maximum available anti-slip friction force, providing accurate data for subsequent decision-making and improving the safety protection capability of tunneling on steep slopes.

[0109] According to yet another embodiment of the invention, the final operating condition decision is made based on the recorded maximum available anti-slip friction:

[0110] If the maximum available anti-slip friction force is greater than or equal to the total tension friction force requirement, the system is determined to be able to work stably under the current working conditions and maintain the current parameters to complete this tunneling stroke. During the operation, the low tension force of the abnormal support shoe group, the reduced total thrust, and the compensation tension force of the other group are maintained. The pressure, displacement change rate, and total friction force of all support shoe cylinders are continuously monitored until this stroke is completed.

[0111] If the maximum available anti-slip friction force is less than the total tension friction force requirement, the system is deemed to have insufficient anti-slip capability and an early warning is issued. The control system first performs internal optimization of the tension force on the remaining normal support shoe cylinders within the main support shoe group to which the abnormal support shoe cylinder belongs, ensuring that the displacement change rate of each support shoe cylinder does not exceed its warning threshold. The principle of internal optimization is that the displacement change rate of each normal support shoe cylinder does not exceed its warning threshold, and the tension force is evenly distributed. During the optimization process, the tension force of the normal support shoe cylinders is gradually adjusted, and the displacement change rate is monitored every 20kN adjustment to ensure compliance with the principle. Internal optimization refers to the redistribution of the tension force of the remaining normal support shoes within the main support shoe group to which the abnormal support shoe belongs. The optimization process follows two principles: First, ensure that after redistribution, the displacement change rate of each support shoe in the group does not exceed its respective dynamic warning threshold; second, under the premise of satisfying the first principle, make the tension force of each support shoe in the group as uniform as possible. The specific algorithm for internal optimization of tension force adopts the deviation distribution method, which divides the tension force to be supplemented equally according to the number of normal support shoe cylinders. After each adjustment, the deviation of the displacement change rate of each cylinder is calculated. If the deviation does not exceed ±0.02mm / s, it is judged as uniform distribution.

[0112] If, after internal optimization, the total friction of the system cannot meet the total clamping friction requirement, the total thrust will be gradually reduced to the minimum preset value, and the total clamping friction requirement will be recalculated after each reduction in thrust. The minimum preset value is set to 800kN, the thrust reduction is set to 200kN each time, and the reduction is held for 1 second before recalculating the total clamping friction requirement. During operation, the total thrust is gradually reduced according to a set range. After each reduction, the required value is recalculated and compared with the maximum available anti-slip friction force to determine whether the requirement is met. The setting of a thrust reduction range of 200kN and a holding time of 1s is based on the fact that 200kN corresponds to 10%-15% of the total thrust, and holding for 1s allows the friction force to return to a stable state, avoiding frequent adjustments. The minimum preset value of the total thrust is a safety baseline to ensure the basic functions and safety of the equipment. Its setting comprehensively considers the following factors: the minimum thrust required to overcome mechanical friction and inertia to maintain the cutterhead idling or minimum speed; the lower limit of pressure to avoid creeping instability in the propulsion hydraulic cylinder under extremely low pressure; and the equipment pressure holding requirements defined in engineering. This value needs to be experimentally calibrated according to the hydraulic system and transmission characteristics of the specific tunnel boring machine model.

[0113] If, when the total thrust reaches the minimum preset value, the recalculated total tensioning friction requirement exceeds the maximum available anti-slip friction, the current tunneling process will be unconditionally interrupted, triggering a wellbore instability alarm. The maintenance strategy for the support shoe assembly will be interrupted, with the tensioning force replenished every 5 minutes at a rate of 5% of the current pressure to ensure continuous resistance to the sliding force. Simultaneously, the audible and visual alarms will be activated, linking to the on-site monitoring system to upload operational data in real time. During operation, the propulsion and conveying systems will be interrupted, maintaining all support shoe assemblies in their current tensioned state to prevent the main unit from sliding. An audible and visual alarm will also be issued to remind operators to take manual measures to check the wellbore condition and equipment malfunctions.

[0114] By adopting this technical solution, the present invention prioritizes internal optimization and thrust reduction to compensate for friction gaps through a tiered decision-making logic, thereby minimizing project delays; it clarifies the handling paths for different risk levels to avoid safety accidents caused by forced tunneling or inefficiency caused by excessive conservatism; it maintains a taut state when tunneling is interrupted to prevent the main unit from slipping and ensure equipment safety; and it accurately issues early warnings and handling alarms, providing time and basis for manual intervention, thereby improving the controllability and safety of steep slope tunneling.

[0115] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for TBM excavation of inclined shafts with steep gradients, characterized in that, Includes the following steps: Establish a benchmark for the excavation of a double-supported full-face tunnel boring machine under steep slope conditions. The steep slope conditions are the conditions for inclined shaft excavation where the angle between the axis of the inclined shaft and the horizontal plane is 15°-35°. Start the tunneling machine and perform one tunneling advance stroke, with a stroke length of 300mm-800mm. At the same time, continuously monitor the first real-time tension force applied to the well wall by the first main support shoe group and the second real-time tension force applied to the well wall by the second main support shoe group. Based on the preset total weight of the tunneling machine host and the real-time tunneling inclination angle, the downward component of the tunneling machine host's gravity along the inclined shaft axis is calculated in real time. With the control objective of resisting the downward force, the target value of the second real-time support force required by the second main support shoe group is calculated based on the downward force, the preset safety margin, and the friction coefficient between the well wall and the support shoe. Using the second real-time tensioning target value as a constraint, and combined with the preset effective tunneling thrust range of the cutterhead, the first real-time tensioning force of the first main support shoe assembly and the total thrust of the tunneling machine's propulsion hydraulic cylinder are calculated; based on the calculation results, the second real-time tensioning force, the first real-time tensioning force, and the total thrust of the propulsion hydraulic cylinder are set synchronously and dynamically, wherein the safety margin is a preset additional friction force value, which is between 50kN and 300kN; Once the tunneling of this stroke is completed, the advance is stopped and the first and second main support shoe groups are kept in a taut state. The return hydraulic cylinder of the tunneling machine is activated, causing the main body of the tunneling machine to move forward one stroke along the axis of the inclined shaft. During the forward movement, the current value of the drive motor of the screw conveyor in the tunneling machine is monitored in real time. The real-time signal of the drive motor current value is used as a feedforward control variable and input to the control system corresponding to the continuous belt conveyor set behind the tunneling machine. According to a predetermined proportional coefficient, the running linear speed of the continuous belt conveyor is kept in a real-time proportional relationship with the current value of the drive motor. This proportional coefficient is between 0.01m / (s·A) and 0.05m / (s·A).

2. The steep-slope inclined shaft TBM tunneling method as described in claim 1, characterized in that, During the step of activating the return hydraulic cylinder to move the main body of the tunneling machine forward by one stroke, the running linear speed of the continuous belt conveyor behind the tunneling machine is controlled as follows: The current value of the drive motor of the screw conveyor is used as the main adjustment signal, and the torque value of the drive roller of the continuous belt conveyor is collected in real time as the feedback correction signal. The control system of the continuous belt conveyor first calculates the initial target linear velocity based on the current value of the drive motor and a predetermined proportional coefficient. At the same time, based on the initial target linear velocity and a preset load-speed model, the control system calculates the expected torque range corresponding to the expected flow rate of excavated soil at that linear velocity. The load-speed model is preset according to the tunneling parameters and the characteristics of the excavated soil. The real-time torque value of the drive roller is compared with the expected torque range: if the real-time torque value is consistently higher than the upper limit of the expected torque range, and this state lasts for more than a first set duration, the control system determines that the actual load of the continuous belt conveyor is greater than the expected load, and adds a positive speed compensation amount to the initial target linear speed. The magnitude of the positive speed compensation amount is proportional to the extent to which the real-time torque value exceeds the upper limit of the expected torque range; if the real-time torque value is consistently lower than the lower limit of the expected torque range, and this state lasts for more than a second set duration, the control system determines that the actual load is less than expected or there is a risk of slippage, and controls the continuous belt conveyor to perform a deceleration process. During the deceleration process, the real-time torque value of the drive roller is continuously monitored, and it is determined whether it has recovered to the expected torque range; if it has recovered, the deceleration process is terminated and the current operating linear speed is maintained. The deceleration rate during the deceleration process is lower than the preset maximum value.

3. The steep-slope inclined shaft TBM tunneling method as described in claim 2, characterized in that, When comparing the real-time torque value of the drive roller with the expected torque range, if the real-time torque value continuously deviates from the expected torque range, the following operating condition mode determination is performed: The effective value change rate of the current of the screw conveyor drive motor and the speed following error of the continuous belt conveyor drive motor are calculated simultaneously. Based on the following quantitative criteria, the mode for real-time identification of abnormal operating conditions is as follows: When the short-term change rate of the real-time torque value is lower than the first threshold and the change rate of the effective current value is lower than the second threshold, it is determined to be a stable change mode of the actual load. If the real-time torque value shows a positive peak exceeding the third threshold within the preset time window, and the speed following error shows an instantaneous deviation exceeding the fourth threshold within the associated time window where this peak occurs, it is judged as a large material or mechanical instantaneous jamming mode. When the real-time torque value remains above the upper limit of the expected torque range for a duration that reaches the fifth threshold, and the average value within its rolling time window shows a monotonically increasing trend, it is identified as a continuous overload mode.

4. The steep-slope inclined shaft TBM tunneling method as described in claim 3, characterized in that, Based on the identified operating mode, switch and execute the corresponding control strategy in real time: If the actual load is determined to be in a stable change mode, then speed compensation or deceleration based on torque feedback is executed. If the system is identified as a large piece of material or a momentary mechanical jamming mode, the current speed-based control command is immediately interrupted, and the continuous belt conveyor is controlled to limit and stabilize the output torque of its drive motor at a preset safe torque threshold for a first preset duration. After the first preset duration ends, the torque limiting state is exited, and the closed-loop control of the continuous belt conveyor's running linear speed is restored based on the drive motor current value of the screw conveyor. If the system is determined to be in a continuous overload mode, a load reduction operation procedure is initiated. This procedure includes: gradually reducing the target linear velocity by a preset decreasing step size based on the proportion by which the real-time torque value exceeds the upper limit of the expected torque range, until the real-time torque value returns to the expected torque range.

5. The steep-slope inclined shaft TBM tunneling method as described in claim 1, characterized in that, The process of starting the tunneling machine and executing one tunneling propulsion stroke further includes real-time monitoring and dynamic early warning settings for the bearing condition of the wellbore, specifically: Real-time monitoring of the extension displacement rate of each support shoe cylinder in the first and second main support shoe groups; Based on the assessment information of the rock mass stability ahead of the current tunneling section, and the correspondence between the pressure and displacement change rate of each support shoe cylinder recorded in the stable wellbore section during historical tunneling, a warning threshold for the displacement change rate is dynamically set for each support shoe cylinder.

6. The steep-slope inclined shaft TBM tunneling method as described in claim 5, characterized in that, When the displacement change rate of any support shoe cylinder exceeds its warning threshold, the control system immediately executes primary control and graded judgment, specifically: S1. Control the abnormal support shoe cylinder to reduce the tension force to a preset initial low value; S2. Simultaneously reduce the total thrust of the hydraulic cylinder by a preset percentage; S3. Within the first set time window after executing steps S1 and S2, continuously monitor the displacement change rate of the abnormal support shoe cylinder and make a graded judgment accordingly: If the displacement change rate has dropped below its warning threshold before the end of the first time window, a controlled state determination is made: if the displacement change rate drops by more than a preset proportion of its initial excess, it is determined to be a first type of response condition. At this time, the control system restores the tensioning force of the abnormal support shoe cylinder to the value before it executes step S1, and adjusts the total thrust to the value before it executes step S2, and continues the current stroke tunneling. If the rate of displacement change drops below the warning threshold within the first time window, and the rate of decrease does not exceed the preset ratio, it is determined to be a second type of response condition; the control system maintains the tension of the abnormal support shoe cylinder at the initial low value and maintains the reduced total thrust to complete the tunneling. If the rate of displacement change is still higher than its warning threshold at the end of the first time window, it is determined to be a third type of response condition and triggers systemic safety adjustment control.

7. The steep-slope inclined shaft TBM tunneling method as described in claim 6, characterized in that, When the system is determined to be in a Category III response condition and triggers systemic safety adjustment control, the control system executes the following steps: Maintain the abnormal support shoe low tension force set in step S1 and the total thrust set in step S2, while continuously monitoring the pressure and displacement change rate of all support shoe cylinders; when the fluctuation amplitude of the pressure and displacement change rate is continuously lower than their respective preset stability thresholds, it is determined that the current working condition has entered a stable state. After determining that the current working condition has entered a stable state, evaluate the average pressure and average displacement rate of the other normal support shoe cylinders in the main support shoe group to which the abnormal support shoe cylinder belongs. While maintaining the current reduced total thrust level, recalculate the total clamping friction force required to resist the sliding component force, and calculate the actual total friction force that all support shoe cylinders can provide at present based on the real-time working pressure of each support shoe cylinder. Calculate the friction gap value, which is the difference between the total required tension friction force and the actual total friction force. The friction gap value is compensated by increasing the overall tension force of another main support shoe group. During the process of increasing the tension force, the displacement change rate of all support shoe cylinders in this group is monitored in real time. If, during the process of increasing the tension, the displacement rate of any support shoe cylinder in the other main support shoe group exceeds its warning threshold, the increase of the tension of that group shall be stopped immediately, and the total friction force provided by the support shoe cylinders of that group at this time shall be recorded as the maximum available anti-slip friction force under the current working condition.

8. The steep-slope inclined shaft TBM tunneling method as described in claim 7, characterized in that, Final operating condition decision based on the recorded maximum available anti-slip friction: If the maximum available anti-slip friction force is greater than or equal to the total tightening friction force requirement, the system is determined to be able to work stably under the current working conditions and maintain the current parameters to complete this tunneling stroke. If the maximum available anti-slip friction force is less than the total tension friction force requirement, the system is deemed to have insufficient anti-slip capability and an early warning is issued. The control system first optimizes the tension force on the other normal support shoe cylinders in the main support shoe group to which the abnormal support shoe cylinder belongs, on the premise that the displacement change rate of each support shoe cylinder does not exceed its early warning threshold. The principle of internal optimization is that the displacement change rate of each normal support shoe cylinder does not exceed its early warning threshold and the tension force is evenly distributed. If, after internal optimization, the total friction of the system cannot meet the total clamping friction requirement, the total thrust will be gradually reduced to the minimum preset value, and the total clamping friction requirement will be recalculated after each reduction in thrust. If the total thrust reaches the minimum preset value and the recalculated total clamping friction requirement is greater than the maximum available anti-slip friction, the current tunneling process will be unconditionally interrupted and a wellbore instability handling alarm will be triggered.