Real-time matching control method for pipe jacking force and stratum resistance of sand and gravel stratum

Abstract

The application discloses a kind of sandy gravel stratum pipe jacking force-stratum resistance real-time matching control method, belong to underground engineering pipe jacking construction technical field, solve the technical problem that sandy gravel stratum in jacking force and stratum resistance mismatching easily cause pipe jamming, ground upheaval or settlement.The method is by real-time acquisition jacking cylinder pressure calculation jacking force, synchronous acquisition cutterhead torque, screw conveyor speed and earth pressure, based on the sudden gradient of torque and speed ratio identifies resistance sudden change area and dynamically predicts target resistance;According to the real-time deviation of jacking force and target resistance, jacking speed, grouting pressure and screw conveyor speed are linked and adjusted;Through grouting closed-loop control and earth pressure fluctuation analysis, determine abnormal permeation area and correct permeability coefficient, realize the real-time dynamic matching of jacking system parameters and stratum resistance.It is mainly used for safe and efficient propulsion control of sandy gravel stratum pipe jacking construction.

Description

Technical Field

[0001] This invention relates to the field of underground engineering pipe jacking construction technology. More specifically, this invention relates to a real-time matching control method for pipe jacking force and formation resistance in gravel and sand formations. Background Technology

[0002] Gravel and sand formations, as typical heterogeneous geological bodies, pose severe challenges to pipe jacking construction due to their engineering characteristics. The random distribution of gravel and sand in these formations creates a highly heterogeneous structure, leading to dramatic fluctuations in cutterhead cutting resistance and pipe-soil friction (the frictional resistance generated between the outer wall of the pipe section and the surrounding soil due to relative movement). Especially when large-diameter gravel clusters are locally concentrated, they can cause instantaneous jumps in jacking force during the jacking process, making it difficult for traditional construction control methods to effectively cope with such abrupt changes.

[0003] In terms of matching and controlling the jacking force with the formation resistance, existing technologies mainly rely on feedback adjustment using a single parameter, the pressure of the jacking cylinder. This method cannot identify the fundamental changes in formation resistance caused by differences in the spatial distribution of gravel in sand and gravel formations. When encountering abrupt changes in resistance, there is often a response lag of 3 to 5 rings. This lag effect can easily cause overload or underload of the jacking system, thereby inducing pipe section jamming or even excessive surface subsidence.

[0004] Existing grouting control strategies mostly employ fixed pressure or linear velocity correlation models, which are difficult to adapt to the high variability of permeability in gravel formations. The random distribution of seepage channels in gravel layers causes grout diffusion to exhibit strong nonlinear characteristics. Conventional grouting pressure settings often fail to match the actual permeability requirements of the formation, resulting in incomplete lubrication film formation or excessive grout permeation.

[0005] For soil removal system control, current technologies generally establish a simple linear relationship between the screw conveyor speed and the jacking speed. However, in gravel strata, the intermittent jamming of the screw blades by gravel can significantly alter soil removal efficiency. Existing control models do not establish a coupling analysis mechanism between torque and speed, resulting in soil pressure fluctuations that often exceed the safety threshold.

[0006] Of particular note is the lack of ability to predict abrupt changes in formation resistance in existing technologies. When the cutterhead encounters a gravel mass, the sudden increase in jacking force often occurs 1-2 seconds after physical contact, while the control system takes at least 5 seconds to detect the change in cylinder pressure and respond. This time difference results in the overshoot of jacking force in gravel formation pipe jacking construction generally reaching 15%-25% of the design value, becoming a core bottleneck restricting construction accuracy.

[0007] In summary, in the construction of pipe jacking in gravel strata, it is still necessary to solve the problem of real-time and accurate matching between jacking force and stratum resistance, especially the advanced prediction and dynamic compensation of resistance change zones, in order to eliminate the response lag and overshoot of traditional control methods and avoid pipe section jamming and uncontrolled surface settlement. Summary of the Invention

[0008] One object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages that will be described later.

[0009] Another objective of this invention is to provide a real-time matching control method for pipe jacking force and formation resistance in gravel formations. This method identifies sudden changes in resistance in real time and dynamically predicts the target formation resistance, and adjusts the jacking speed, grouting pressure, and soil removal parameters in a coordinated manner. This effectively adapts to the abrupt changes in gravel formation characteristics and reduces the risk of pipe jamming and ground deformation.

[0010] To achieve these objectives and other advantages according to the present invention, a real-time matching control method for pipe jacking force and formation resistance in gravel formations is provided, comprising:

[0011] 1. A method for real-time matching and control of pipe jacking force and formation resistance in gravel and sand formations, characterized in that it includes:

[0012] S1. Real-time acquisition of the pressure value P of the jacking machine's hydraulic cylinder. c Calculate the current jacking force F c :F c =k1×P c ×A;

[0013] S2, Synchronously acquire cutter head torque T and screw conveyor speed N s and excavation pressure P s Based on the coupling effect of gravel on the cutterhead and screw conveyor in the gravel strata, the relationship between T and N is calculated. s Mutation gradient M: M = ▽ (T / N) s When the abrupt change gradient M exceeds the preset threshold N, it is determined to be a zone of abrupt change in resistance of gravel strata;

[0014] S3. When a zone of abrupt change in resistance is identified in gravel formations, dynamically predict the target formation resistance F. r :F r =F0+k2(MN);

[0015] S4. Based on the current jacking force F c With the target formation resistance F r Real-time deviation value ΔF: ΔF = F c -F r Real-time adjustment of the jacking system:

[0016] like If ΔF ≤ B, then maintain the current jacking parameters; if ΔF > B, then execute: decrease the jacking speed V and increase the grouting pressure P in conjunction. j Press N s =λ×V reduces the screw conveyor speed; if ΔF<-B, then execute: increase the jacking speed V, and simultaneously reduce the grouting pressure P. j Press N s =λ×V increases the speed of the screw conveyor;

[0017] S5, P fed back by the grouting pressure sensor j Actual value, closed-loop control of the grouting pump output, making P j The jacking speed V satisfies: P j =f×V 0.5 Real-time data based on the excavation pressure P s Standard deviation σ s If σ s If the permeability coefficient is greater than σ0, it is determined to be a gravel formation with abnormal permeability. The permeability coefficient f' of the gravel formation is dynamically corrected as follows: f' = f + k3(σ s -σ0);

[0018] Where A is the effective working area of ​​the hydraulic cylinder, in meters. 2 ;

[0019] k1 is the system efficiency coefficient, obtained from the hydraulic cylinder no-load propulsion calibration test, with a value of 0.85~0.95;

[0020] k2 is the particle size influence factor determined based on the gravel gradation, k2=0.3d 1.5 d. Maximum gravel size in the gravel layer, mm;

[0021] F0 is the design reference resistance, in kN;

[0022] λ is the soil removal efficiency coefficient for gravel strata, expressed in rpm·min / mm, and λ = Q / 1.4S, where Q is the theoretical discharge capacity of the screw conveyor, expressed in m³ / s. 3 / min; S is the cross-sectional area of ​​the pipe section, m 2 ;

[0023] B is the resistance tolerance, in kN, and is taken as 5%~10% of F0;

[0024] f is the permeability coefficient of the gravel formation; σ0 is the statistical value of the standard deviation of the excavation pressure in the test section of the homogeneous gravel formation, in MPa.

[0025] k3 is the permeability correction factor, MPa -1 ·s -0.5 .

[0026] Preferably, the permeability correction factor k3 is calibrated by performing the following operations during trial inference in gravel formations: fixing the jacking speed V at 20 mm / min; and adjusting the initial grouting pressure P... j0 Begin by gradually increasing the grouting pressure and recording the standard deviation σ of the soil pressure after each increase. s According to the formula = Calculate the values ​​for each working condition; take the arithmetic mean of k3 for each working condition as the final calibration value of k3.

[0027] Preferably, in step S3, if the measured deviation value of the jacking force for three consecutive rings is... If the value is greater than 15%, then a dynamic correction of the particle size influence factor k2, determined based on the gravel gradation, is initiated: k2' = k2 + M i -N>0.1s -1 And F c,i -F0>50kN; where F c,i The pressure value of the inlet cylinder of the i-ring pipe jacking machine; M i For the i-th ring T and N s The mutation gradient.

[0028] Preferably, in step S4, when the jacking pipe is in a curved section and the radius of curvature R < 500D, P j The relationship between P and the jacking speed V is corrected to: j =f×V 0.5 Where D is the outer diameter of the jacking pipe section, in meters; k4 is the curve segment compensation coefficient, with a value of 0.02θ, where θ is the axial deviation angle between pipe sections during curve jacking, in degrees.

[0029] Preferably, the real-time matching control method for pipe jacking force and formation resistance in gravel formations further includes performing a friction reset operation every 100 rings of advance:

[0030] Pause jacking and maintain grouting pressure P j The pressure was 0.8 MPa for 5 minutes.

[0031] The pipe section was slightly retracted by 20mm to release the interfacial shear stress;

[0032] When restarting the jacking, the initial speed is reduced to 60% of the speed before the pause, and then resumed in steps of 10% / min.

[0033] Preferably, the corrected k2, k3, and f' are stored according to the classification of the ground-penetrating radar scan results; when the ground-penetrating radar identifies similar stratigraphic features, the historical optimal parameter combination is automatically called and preloaded.

[0034] Preferably, the mechanism for obtaining the historical optimal parameter combination is as follows:

[0035] Real-time acquisition of ground-penetrating radar scanning signals, extraction of characteristic signals of sand and gravel strata: dielectric constant ρ, reflection wave coefficient φ, and 0.2m scale reflectivity percentage P. 200 ;

[0036] The effect evaluation function based on parameter combination is S=0.5× The parameter combination that minimizes S is the historically optimal parameter combination.

[0037] When the radar identifies that the characteristic signals of the gravel strata are the same, it automatically loads the historical best parameter combination under the same gravel strata.

[0038] The benchmark value for the jacking force fluctuation is the standard deviation of the jacking force in the trial push section.

[0039] Preferably, when the cutterhead rotation speed fluctuation exceeds ±5% of the set value for 10 consecutive seconds, the target formation resistance prediction value in step S3 is adjusted to F. r ':F r '=F r ×8%.

[0040] The present invention has at least the following beneficial effects:

[0041] Firstly, this invention can accurately adapt to sudden changes in resistance in gravel formations. By calculating the sudden change gradient of cutterhead torque and screw conveyor speed in real time, it can dynamically predict the resistance of the target formation, effectively cope with sudden changes in gravel resistance in gravel formations, and reduce the risk of pipe jacking jamming.

[0042] Secondly, this invention can achieve intelligent correction of permeability anomalies. Based on the step grouting test, the permeability correction factor k3 is calibrated, and the permeability coefficient is corrected in real time by combining the standard deviation of the soil pressure. This significantly improves the control accuracy of grouting pressure in permeable gravel strata and reduces strata disturbance.

[0043] Thirdly, this invention can also achieve adaptive gradation changes. When the continuous jacking deviation exceeds the limit, it automatically corrects the particle size influence factor k2, dynamically optimizes the resistance prediction model, adapts to the spatial variability of sand and gravel gradation, and avoids jacking force loss of control caused by error accumulation.

[0044] Fourth, this invention introduces a pipe section deviation angle compensation coefficient when the radius of curvature of the curved section is small, corrects the grouting pressure-jacking speed relationship, effectively compensates for the additional resistance of curved jacking, and suppresses surface subsidence caused by formation loss.

[0045] Fifth, the present invention periodically performs micro-retraction of pipe sections and grouting pressure maintenance to release interfacial shear stress, reset pipe-soil friction resistance, maintain long-term stable operation of the jacking system and extend equipment life;

[0046] Sixth, this invention also achieves automatic preloading of parameters k2, k3 and f' by matching historical optimal parameters with ground-penetrating radar features, thereby improving the construction efficiency of similar strata and reducing trial-and-error costs.

[0047] 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. Attached Figure Description

[0048] Figure 1 This is a flowchart illustrating the real-time matching control method for pipe jacking force and formation resistance in gravel formations as described in this invention. Detailed Implementation

[0049] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0050] It should be understood that terms such as “having,” “comprising,” and “including” used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0051] like Figure 1 This invention provides a real-time matching control method for pipe jacking force and formation resistance in gravel formations, comprising:

[0052] A method for real-time matching and control of pipe jacking force and formation resistance in gravel and sand formations, characterized by comprising:

[0053] S1. Real-time acquisition of the pressure value P of the jacking machine's hydraulic cylinder. c Calculate the current jacking force F c :F c =k1×P c ×A;

[0054] S2, Synchronously acquire cutter head torque T and screw conveyor speed N s and excavation pressure P s Based on the coupling effect of gravel on the cutterhead and screw conveyor in the gravel strata, the relationship between T and N is calculated. s Mutation gradient M: M = ▽ (T / N) s When the abrupt change gradient M exceeds the preset threshold N, it is determined to be a zone of abrupt change in resistance of gravel strata;

[0055] S3. When a zone of abrupt change in resistance is identified in gravel formations, dynamically predict the target formation resistance F. r :F r =F0+k2(MN);

[0056] S4. Based on the current jacking force F c With the target formation resistance F rReal-time deviation value ΔF: ΔF = F c -F r Real-time adjustment of the jacking system:

[0057] like If ΔF ≤ B, then maintain the current jacking parameters; if ΔF > B, then execute: decrease the jacking speed V and increase the grouting pressure P in conjunction. j Press N s =λ×V reduces the screw conveyor speed; if ΔF<-B, then execute: increase the jacking speed V, and simultaneously reduce the grouting pressure P. j Press N s =λ×V increases the speed of the screw conveyor;

[0058] S5, P fed back by the grouting pressure sensor j Actual value, closed-loop control of the grouting pump output, making P j The jacking speed V satisfies: P j =f×V 0.5 Real-time data based on the excavation pressure P s Standard deviation σ s If σ s If the permeability coefficient is greater than σ0, it is determined to be a gravel formation with abnormal permeability. The permeability coefficient f' of the gravel formation is dynamically corrected as follows: f' = f + k3(σ s -σ0);

[0059] Where A is the effective working area of ​​the hydraulic cylinder, in meters. 2 ;

[0060] k1 is the system efficiency coefficient, obtained from the hydraulic cylinder no-load propulsion calibration test, with a value of 0.85~0.95;

[0061] k2 is the particle size influence factor determined based on the gravel gradation, k2=0.3d 1.5 d. Maximum gravel size in the gravel layer, mm;

[0062] F0 is the design reference resistance, in kN;

[0063] λ is the soil removal efficiency coefficient for gravel strata, expressed in rpm·min / mm, and λ = Q / 1.4S, where Q is the theoretical discharge capacity of the screw conveyor, expressed in m³ / s. 3 / min; S is the cross-sectional area of ​​the pipe section, m 2 ;

[0064] B is the resistance tolerance, in kN, and is taken as 5%~10% of F0;

[0065] f is the permeability coefficient of the gravel formation; σ0 is the statistical value of the standard deviation of the excavation pressure in the test section of the homogeneous gravel formation, in MPa.

[0066] k3 is the permeability correction factor, MPa-1 ·s -0.5 .

[0067] The above technical solution senses changes in the formation state in real time, especially sudden changes in resistance and abnormal permeability, and dynamically predicts the target formation resistance based on changes in formation state. This allows for precise control of the jacking system parameters, ensuring real-time matching between the jacking force and the formation resistance. This avoids problems such as pipe jamming due to insufficient jacking force or ground heave and equipment overload due to excessive jacking force.

[0068] The above technical solution includes real-time monitoring and calculation of the jacking force, using a pressure sensor to collect the pressure value P of the main jacking cylinder of the pipe jacking machine in real time. c (Unit: MPa), and combined with the effective working area A of the hydraulic cylinder (unit: m2) and the system efficiency coefficient k1 (empirical value range: 0.85~0.95), calculate the current actual jacking force F. c (Unit: kN), F c =k1×P c ×A. Where k1 is determined through a cylinder no-load propulsion calibration test based on the specific equipment, taking into account operational system losses and frictional losses for precise determination. The pressure sensor is a high-precision pressure sensor, such as the Honeywell ST series, which is installed in the inlet and / or return oil lines of the main jacking cylinder, close to the cylinder body, to ensure that the pressure measurement accurately reflects the cylinder thrust.

[0069] The above technical solution also includes the step of identifying abrupt changes in formation resistance, and simultaneously collecting the cutterhead drive torque T (unit: kN·m) and the screw conveyor speed N. s (Unit: rpm). Calculate the ratio T / N. s The mutation gradient M (i.e., the gradient operator ▽(T / N)) s When M exceeds a preset threshold N, it is determined that the formation has entered a region of abrupt change in resistance within a gravel stratum. This mechanism is based on the coupled resistance effect of gravel in the gravel stratum on the cutterhead cutting (torque) and the screw conveyor's slag discharge (speed). The cutterhead driving torque T is obtained through a cutterhead torque sensor installed at the drive end (motor side) or output end (cutterhead side) of the cutterhead drive spindle, and the screw conveyor speed N... s The soil discharge pressure P is measured by a screw conveyor speed sensor installed on the screw conveyor drive motor shaft or reducer output shaft. s The soil pressure is measured by a pressure sensor installed in the pressure chamber of the screw conveyor's outlet (slag discharge port). Based on the identification of abrupt changes in formation resistance, dynamic prediction of the target formation resistance is further performed. Once a resistance abrupt change zone (M>N) is identified, the prediction is immediately based on the degree of change (M - N) and the particle size influence factor k2 (k2=0.3d) calibrated based on the gravel gradation. 1.5d is the maximum gravel size in mm. Based on the baseline design resistance F0 (unit: kN), the target formation resistance Fr required at present is dynamically predicted. r =F0 + k2(MN) (unit: kN). The k2 formula reflects the significant amplification effect of large-diameter gravel on the increase in resistance. The d value needs to be determined through geological exploration (common range: 20mm~100mm+). F0 is calculated based on the geological report and design. N (mutation threshold) needs to be calibrated in the trial section, where the pipe jacking machine is operated at a moderate and stable jacking speed. Maintain relatively constant key parameters such as cutterhead speed and grouting pressure, record the ratio of cutterhead torque to screw conveyor speed, and set a safety threshold N based on its maximum variation range, generally not exceeding 1.5 times the maximum variation range.

[0070] The above technical solution also includes real-time control of the jacking system and calculation of the current jacking force F. c With target resistance F r The real-time deviation ΔF, if If the thrust is ≤B (B is the resistance tolerance, ranging from 5% to 10% of F0), then the current jacking parameters are maintained. If ΔF > B, the jacking force is too large, then the jacking speed V is reduced, and the grouting pressure P is increased accordingly. j Press N s =λ×V reduces the screw conveyor speed, where λ is the soil discharge efficiency coefficient (λ = Q / (1.4 ×S), and Q is the theoretical discharge capacity of the screw conveyor in m³). 3 / min, S is the cross-sectional area of ​​the pipe section in m² 2 To ensure that the amount of soil removed matches the jacking speed, avoid over- or under-discharge. If ΔF < -B, indicating insufficient jacking force, then: increase the jacking speed V and simultaneously reduce the grouting pressure P. j Press N s =λ×V increases the screw conveyor speed. Further, the grouting pressure sensor (P) is used to... j Feedback of actual values, closed-loop control of grouting pump output, so that P j The relationship P satisfies with the jacking speed V. j =f×V 0.5 (f is the initial permeability coefficient of the gravel formation). The aim is to dynamically adjust the grout injection pressure based on the advance speed to optimize the friction reduction effect. The soil pressure P is calculated in real time. s Standard deviation σ s (Reflecting the degree of fluctuation in soil discharge pressure), if σ s >σ0 (σ0 is the standard deviation of the statistical analysis of the homogeneous stratum trial section), is judged as a permeability anomaly zone (such as the presence of lenses, interlayers, etc.), and the dynamic correction permeability coefficient f' = f + k3× (σs - σ0) (k3 is the permeability correction factor, unit MPa) is calculated.-1 ·s -0.5 The revised f' is used to update the formula for the grouting pressure target value P. j =f×V 0.5 .

[0071] Based on the above technical solution, a specific workflow of the present invention is as follows:

[0072] Initial and Continuous Monitoring: The pipe jacking machine starts its advance in the gravel and sand strata. The control system continuously collects key data at high frequency: main jacking cylinder pressure, cutterhead drive torque, screw conveyor speed, and outlet pressure. The system calculates the current actual jacking force and the ratio of cutterhead torque to screw conveyor speed in real time.

[0073] Sudden Change Identification and Target Setting: When the system detects a sudden and sharp increase in the rate of change of the torque / speed ratio, exceeding a preset threshold (e.g., the cutterhead encountering dense clusters of large rocks causing a surge in torque and a decrease in speed), it immediately determines that it has entered a resistance change zone. Based on the severity of this change and the known maximum rock size in the strata, the system dynamically calculates and sets a higher target resistance value on top of the foundation design resistance value, which serves as the jacking force required for this difficult section.

[0074] Deviation Analysis and Parameter Adjustment: The system immediately compares the current actual jacking force with the newly set target resistance value. Assuming the actual jacking force is significantly lower than the target value (excessive negative deviation, posing a risk of machine jamming), the control system immediately implements adjustments: increasing the propulsion speed to increase thrust; simultaneously adjusting the grouting pressure according to speed changes (avoiding excessive grouting when thrust is insufficient); and automatically increasing the screw conveyor speed to match the increased propulsion speed, ensuring smooth soil removal. This series of actions aims to rapidly increase the actual jacking force, bringing it closer to the target value.

[0075] Permeability Monitoring and Correction: During the grouting process, the system continuously monitors the stability of the outlet pressure. If drastic fluctuations in outlet pressure are detected (with a standard deviation significantly greater than the baseline value for normal, uniform formations), this indicates a local anomaly in formation permeability (such as encountering highly permeable sand layers). The system then dynamically adjusts the permeability coefficient used to calculate the target grouting pressure value based on the magnitude of the abnormal fluctuations (increasing the coefficient in permeable zones). The updated permeability coefficient takes effect immediately, and the closed-loop grouting control system adjusts the pressure output of the grouting pump accordingly to ensure that the slurry injection pressure adapts to the new formation conditions, maintaining effective lubrication and formation support.

[0076] Stable Progress: After adjustments, when the actual jacking force recovers to within the allowable tolerance range of the deviation from the target resistance value, the system maintains the current combination of parameters such as jacking speed, grouting pressure, and screw conveyor speed, achieving stable and safe continuous jacking. The entire closed-loop process of perception-prediction-decision-adjustment continuously cycles, ensuring that the pipe jacking machine can intelligently and adaptively cope with the complex and variable characteristics of gravel strata.

[0077] According to the above technical solution, it can identify sudden changes in jacking resistance caused by large-diameter gravel or dense layers in gravel strata in real time. Once a sudden risk is identified, the system predicts the target resistance value required for that section in advance and actively and dynamically adjusts the jacking speed, grouting pressure, and soil removal speed. This effectively avoids insufficient jacking force due to a sudden increase in resistance (leading to pipe jamming and ground collapse) or excessive jacking force due to blind jacking (causing pipe section damage, ground heave, and equipment overload) in traditional methods. It significantly improves the safety and continuity of construction in complex gravel strata and reduces unplanned downtime. By monitoring the fluctuation characteristics of soil removal pressure in real time, it intelligently judges local anomalies in stratum permeability (such as seepage channels or water-resistant interlayers). After an anomaly is detected, the key parameter (permeability coefficient) of grouting pressure control is immediately and dynamically corrected, and the target value of grouting pressure is updated in real time. This allows the grouting system to adapt to changes in stratum permeability: automatically increasing grouting pressure in high-permeability areas to ensure the formation of an effective mud jacket, and avoiding excessive pressure that could fracture the strata in low-permeability areas. Closed-loop control ensures precise regulation of grouting pressure, maximizes the friction-reducing effect of the grout, effectively supports the excavation face and controls the deformation of the surrounding strata, reducing the risk of surface subsidence and grout loss. Simultaneously, an intelligent linkage mechanism is established between the advance speed, grouting pressure, and screw conveyor speed. When adjusting the core parameter, the advance speed, the grouting pressure and soil removal speed automatically and collaboratively change according to a preset engineering logic relationship (the grouting pressure dynamically adjusts with the square root of the speed, and the soil removal speed is proportional to the advance speed). This ensures that the soil removal volume always matches the advance volume (preventing over-excavation or under-excavation), and that the grouting pressure matches the advance speed and stratum characteristics (optimizing lubrication and stratum stability). This allows the three core functions of the pipe jacking system—thrust, soil removal, and friction reduction—to maintain efficient and coordinated operation under dynamic stratum conditions, significantly improving the controllability, stability, and overall efficiency of the construction process, while reducing excessive reliance on the individual experience of operators.

[0078] In one technical solution, the permeability correction factor k3 is calibrated by performing the following operations during trial inference in gravel formations: fixing the jacking speed V at 20 mm / min; and adjusting the initial grouting pressure P... j0 Begin by gradually increasing the grouting pressure and recording the standard deviation σ of the soil pressure after each increase. s According to the formula = Calculate the values ​​for each working condition; take the arithmetic mean of k3 for each working condition as the final calibration value of k3.

[0079] The above technical solution quantifies the sensitivity of permeability coefficient correction by actively changing the grouting pressure and observing the formation response (fluctuation of soil pressure) under controllable test conditions. A homogeneous gravel formation was selected for calibration, and the jacking speed V was strictly fixed at 20 mm / min to eliminate the influence of changes in jacking speed on the fluctuation of soil pressure. This ensured that the observed fluctuations primarily reflected the relationship between grouting pressure changes and formation permeability, starting from a relatively low initial grouting pressure (P). j0 Begin with the grouting process. Then, gradually increase the grouting pressure in preset, controllable steps. After each pressure increase, allow the system to stabilize for a short period (e.g., a few minutes) to allow the formation response (exit pressure) to reach a new stable state. After each grouting pressure increase and stabilization, the system continuously monitors the pressure (P) at the screw conveyor outlet. s Calculate and record the standard deviation (σ) of the soil pressure Ps under this steady-state condition. s Standard deviation σ s The fluctuation of the grouting pressure is quantified, serving as a direct indicator of the sensitivity of formation permeability to changes in grouting pressure. The greater the change in permeability, the higher the σ... s For P j The system is more sensitive to changes in pressure. For each increase in grouting pressure, the system calculates a temporary k3 value. This temporary k3 value represents the proportional relationship between the unit change in soil pressure fluctuation and the adjustment amount of grouting pressure under this specific pressure change, while also considering the influence of a fixed jacking speed. After completing all preset grouting pressure step increase operations, the system obtains multiple temporary k3 values ​​(corresponding to different pressure change conditions). Finally, the arithmetic mean of all these temporary k3 values ​​is taken as the final value of the calibrated permeability correction factor k3 used for subsequent formal jacking control. Taking the average is to obtain a more robust and representative comprehensive indicator.

[0080] According to the above technical solution, a specific workflow is as follows: In the trial section (a section of uniformly geological gravel strata) in the early stage of the project, the jacking speed of the pipe jacking machine is set and stabilized at 20 mm / min. A low initial grouting pressure value is set (e.g., 0.01~0.1 MPa). The control system is prepared to record grouting pressure and soil discharge pressure data. Advancement begins. After running stably at the initial grouting pressure for a few minutes, the system records the soil discharge pressure data at this time and calculates its standard deviation σ. s1 Then, increase the grouting pressure by a predetermined step (e.g., increase by 0.1 MPa). Run the grouting pressure steadily for several minutes, record the soil pressure data under the new pressure, and calculate its standard deviation σ. s2Repeat this process and record σ. s3 For each pressure increase: the system records the change in grouting pressure and the corresponding change in the standard deviation of the soil pressure. Combined with a fixed jacking speed, the system calculates a temporary k3 value characterizing the sensitivity to pressure changes. The system further calculates the arithmetic mean of multiple temporary supports, which is the calibrated permeability correction factor. In subsequent formal jacking, when the system detects permeability anomalies requiring correction of the permeability coefficient f, this calibrated k3 value is used for calculation.

[0081] The above technical solution provides a standardized calibration process based on field measurement data. By actively changing the input (grouting pressure) under controllable conditions (fixed speed, stepped pressure increase) and accurately measuring the output response (fluctuation of soil pressure), this method objectively quantifies the sensitivity of permeability changes in specific gravel formations to grouting pressure adjustments. This significantly improves the accuracy and reliability of the k3 value, thereby ensuring the predictive accuracy and control effect of the permeability anomaly correction logic. Eliminating subjectivity and uncertainty, the above technical solution provides a repeatable and verifiable engineering test method, allowing the determination of the k3 value to be based on the actual formation response data of specific projects. This not only reduces excessive reliance on the operator's personal experience but, more importantly, greatly enhances the adaptability of the entire control system to different gravel formation conditions, ensuring the consistency and scientific validity of the control strategy across different projects, and enabling faster and more accurate calculation of the target grouting pressure value adapted to the permeability characteristics of new formations.

[0082] In one of the technical solutions, in step S3, if the measured deviation value of the jacking force for three consecutive rings is... If the value is greater than 15%, then a dynamic correction of the particle size influence factor k2, determined based on the gravel gradation, is initiated: k2' = k2 + M i -N>0.1s −1 And F c,i -F0>50kN; where F c,i The pressure value of the inlet cylinder of the i-ring pipe jacking machine; M i For the i-th ring T and N s The mutation gradient.

[0083] The above technical solution addresses the prediction error problem that may arise when the initial k2 value, calibrated based on the maximum gravel size, deviates from the expected actual geological gradation. Its core lies in using recent actual construction data to reverse-calibrate the k2 value when the system continuously detects significant and persistent deviations in the jacking force prediction, thereby improving the accuracy of subsequent resistance predictions. During the advancement process, the system continuously monitors the relative deviation between the actual jacking force and the target resistance prediction value for each ring (typically referring to the advancement process of a segment). If the deviation values ​​for three consecutive rings exceed the 15% significance threshold, and simultaneously meet the two additional conditions of a sufficiently large resistance mutation intensity (i.e., the amount by which the mutation gradient exceeds the threshold) and a sufficiently significant amount by which the actual jacking force exceeds the base resistance, the system determines that the initial k2 value may need adjustment. At this point, the system automatically triggers a dynamic k2 correction procedure. This procedure extracts data from these three rings that meet the conditions: the amount by which the actual jacking force exceeds the base resistance for each ring, and the amount by which the resistance mutation intensity for that ring exceeds the threshold. Using these actual data points, the system calculates a provisional k2 value for each ring, which better reflects the actual situation of that ring (the calculation principle is: dividing the actual resistance increment by the mutation intensity increment, reflecting the true response intensity of the formation to the mutation). Finally, the system compares these three provisionally calculated k2 values ​​with the original k2 value, takes the average of their differences, and adds this average to the original k2 value, thus obtaining a new, corrected particle size influence factor k2' calibrated with actual field data. This corrected k2' will be used in the target resistance prediction calculation for subsequent advancing rings. The maximum gravel particle size d provided by geological exploration is an estimate from the design stage; the actual gravel gradation distribution encountered during construction may be more complex and variable. When significant prediction deviations occur in multiple consecutive rings, it indicates that the initial k2 setting can no longer accurately reflect the true response intensity of the current formation to resistance mutations. By using the latest, reliable measured data (resistance increment and mutation intensity) to back-calculate and correct the k2 value, the system can dynamically adapt to changes in actual formation gradation, significantly improving the subsequent target resistance F. r The accuracy of the predictions makes the jacking force control more realistic.

[0084] The heterogeneity of gravel strata poses a significant challenge to construction control. The initially calibrated k2 value may become invalid due to local stratigraphic variations (such as dense gravel zones or changes in grain size distribution). The condition-triggered correction mechanism (continuous exceedance + significant abrupt change) established in the above technical solution can intervene promptly when prediction deviations accumulate and become significant, preventing the control effect from continuously deteriorating due to parameter inaccuracies (such as long-term insufficient or excessive jacking force). It is equivalent to adding an adaptive feedback loop for the key geological parameter k2 to the control system, greatly reducing the absolute dependence on the accuracy of previous geological exploration and enhancing the long-term effectiveness and reliability of the entire control method in complex and unknown strata.

[0085] In one of the technical solutions, in step S4, when the jacking pipe is in a curved section and the radius of curvature R < 500D, P j The relationship between P and the jacking speed V is corrected to: j =f×V 0.5 Where D is the outer diameter of the jacking pipe section, in meters; k4 is the curve segment compensation coefficient, with a value of 0.02θ, where θ is the axial deviation angle between pipe sections during curve jacking, in degrees.

[0086] The above technical solution addresses the special working conditions of curved pipe jacking by introducing an adaptive curvature radius compensation mechanism into the original grouting pressure control logic. Its core is to intelligently adjust the grouting pressure to offset the increased additional resistance in curved sections by dynamically sensing the curvature of the pipe jacking trajectory. The system continuously monitors the curvature radius of the current advancing section of the pipe jacking machine (obtained through the guidance system or pipe section attitude sensors). When the detected curvature radius is less than 500 times the outer diameter of the pipe section (i.e., R < 500D), it determines that a sharp curve section has been entered and triggers the compensation mode. Based on the actual axial deviation angle θ between pipe sections (measured in real time by the hinge angle sensor), a curve section compensation coefficient k4 (k4 = 0.02θ) is generated proportionally. This coefficient directly reflects the lateral compression intensity during pipe section correction. A compensation term that is inversely proportional to the curvature radius and directly proportional to the square of the pipe diameter is superimposed on the original grouting pressure benchmark value (proportional to the square root of the velocity). The smaller the curvature (the sharper the turn) or the larger the pipe diameter, the more significant the increase in compensation pressure, thereby specifically offsetting the additional frictional resistance of the soil outside the curve section on the pipe wall.

[0087] In sharp curves, lateral soil compression caused by pipe section correction significantly increases friction. Traditional uniform grouting strategies can easily lead to a surge in jacking force or pipe section jamming. The above-mentioned technical solution establishes an intelligent mapping between grouting pressure and spatial trajectory through dual sensing of curvature radius and deflection angle. It specifically compensates for the additional resistance on the outside of the curve, effectively preventing runaway jacking force in curved sections and ensuring smooth turning of the pipe section along the designed trajectory. The stress distribution in the soil of curved sections is complex, and standard grouting pressure may not be sufficient to form an effective lubricating mud film on the outside of the curve. This solution uses adaptive pressure compensation to ensure that the outer periphery of the pipe wall, especially in stress concentration areas, is always adequately wrapped with mud, significantly reducing direct friction between the pipe section and the soil, reducing shear disturbance to the strata caused by correction, and fundamentally suppressing the risk of ground settlement or pipe section deformation common in curved sections. The above-mentioned technical solution also incorporates spatial geometric parameters into the real-time control closed loop, enabling the grouting system to have three-dimensional path adaptability. It forms a multi-dimensional synergy with the permeability correction and resistance change correction of straight sections, fully covering the linear / nonlinear advancement scenarios of pipe jacking in gravel strata, and significantly improving the control accuracy and equipment safety of complex trajectory construction.

[0088] In one of the technical solutions, the real-time matching control method for pipe jacking force and formation resistance in gravel formations further includes performing a friction reset operation every 100 rings of advance:

[0089] Pause jacking and maintain grouting pressure P j The pressure was 0.8 MPa for 5 minutes.

[0090] The pipe section was slightly retracted by 20mm to release the interfacial shear stress;

[0091] When restarting the jacking, the initial speed is reduced to 60% of the speed before the pause, and then resumed in steps of 10% / min.

[0092] The above technical solution actively eliminates abnormal interfacial shear forces accumulated during long-term jacking due to local failure of the mud sleeve or stress redistribution in gravel strata by periodically performing friction reset operations (pausing jacking every 100 rings and implementing pressure holding lubrication, micro-retraction of pipe sections, and step restart). During the pressure holding stage, maintaining a grouting pressure of 0.8MPa can repair weak mud films, micro-retraction of 20mm releases the pipe-soil locking stress, and step restart (recovery at an initial speed of 60%+10% / min) avoids a sudden increase in shear stress. This significantly reduces the time-varying friction fluctuations of the jacking system, prevents the risk of pipe section jamming or ground subsidence caused by a sudden surge in jacking force, and improves the stability and safety of continuous construction of long-distance gravel strata pipe jacking.

[0093] In one technical solution, the corrected k2, k3, and f' parameters are stored according to the results of ground-penetrating radar (GPR) scans. When GPR identifies similar stratigraphic features, the system automatically calls the historical optimal parameter combination for preloading. By binding and storing the dynamically corrected key parameters (k2, k3, f') with the rock strata feature maps scanned by GPR, a stratigraphic feature-control parameter knowledge base is established. When the pipe jacking advances to a similar stratigraphic section identified by GPR, the system automatically calls the historical optimal parameter combination for preloading, realizing the self-migration of control parameters driven by stratigraphic characteristics. This significantly reduces the repeated calibration process, avoids the risk of secondary trial and error under the same stratigraphic conditions, and improves the jacking force-resistance matching response speed in complex stratigraphic areas by more than 40%. At the same time, by reusing verified parameter combinations, the system ensures control accuracy and effectively prevents jacking force fluctuations and stratigraphic disturbances caused by parameter adaptation lags.

[0094] In one of the technical solutions, the mechanism for obtaining the historical optimal parameter combination is as follows:

[0095] Real-time acquisition of ground-penetrating radar scanning signals, extraction of characteristic signals of sand and gravel strata: dielectric constant ρ, reflection wave coefficient φ, and 0.2m scale reflectivity percentage P. 200 ;

[0096] The effect evaluation function based on parameter combination is S=0.5× The parameter combination that minimizes S is the historically optimal parameter combination.

[0097] When the radar identifies that the characteristic signals of the gravel strata are the same, it automatically loads the historical best parameter combination under the same gravel strata.

[0098] The benchmark value for the jacking force fluctuation is the standard deviation of the jacking force in the trial push section.

[0099] The above technical solution establishes an intelligent matching library of stratigraphic characteristics and control parameters. It quantifies stratigraphic characteristics through ground-penetrating radar (GPR) scanning and selects optimal control parameters based on multi-dimensional construction effect evaluation. The specific implementation involves three steps: real-time acquisition of GPR signals, analysis of three key indicators of gravel strata—dielectric constant (reflecting density), reflection wave coefficient (characterizing interface impedance), and 0.2-meter scale reflectivity ratio (indicating gravel distribution uniformity)—to form a unique stratigraphic fingerprint; calculation of a comprehensive effect score S for the parameter combination (k2 / k3 / f') used in each stratigraphic section. This score integrates three key indicators: jacking force fluctuation rate (weight 50%, compared to the baseline value of the trial section), surface subsidence (weight 30%, compared to the design allowable value), and grouting consumption (weight 20%, compared to the theoretical design value), with the minimum value of S marked as the optimal parameter combination for the current stratum; when the radar scans a new section matching the historical stratigraphic fingerprint, it automatically retrieves the corresponding optimal parameter set (k2 / k3 / f') and pre-loads it into the control system, skipping the trial-and-error process and directly applying the verified optimal configuration.

[0100] The aforementioned technical solution breaks through the traditional parameter setting mode that relies on manual experience. By accurately mapping radar characteristics with multi-target evaluation, it transforms the physical characteristics of the strata into quantifiable control parameters, enabling the jacking system to possess geologically adaptive intelligence. When the radar identifies similar strata fingerprints, it automatically reuses the historically optimal parameter combination, avoiding repeated adjustments under the same geological conditions, shortening the parameter adaptation time for new sections, and significantly improving the efficiency of continuous construction in complex strata. The multi-target evaluation function (S) coordinates jacking force stability, settlement control, and grouting efficiency, ensuring that the parameter sets used balance construction safety (suppressing sudden changes in jacking force and surface settlement) and resource optimization (avoiding grouting waste), achieving refined control of long-distance pipe jacking at the system level.

[0101] In one technical solution, when the cutterhead rotation speed fluctuation exceeds ±5% of the set value for 10 consecutive seconds, the target formation resistance prediction value in step S3 is adjusted to Fr': Fr' = Fr × 8%. By monitoring the stability of the cutterhead rotation speed in real time (when the fluctuation exceeds ±5% for 10 consecutive seconds), the target resistance prediction value is proactively increased by 8%, pre-compensating for the surge in instantaneous cutting resistance caused by uneven gravel distribution or local hard rock. This effectively avoids the risk of equipment overload or jamming caused by sudden changes in cutterhead torque, while providing a buffer margin for the jacking system and ensuring the continuity and stability of tunneling power output in complex formations.

[0102] 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 illustrations shown and described herein.

Claims

1. A method for real-time matching and control of pipe jacking force and formation resistance in gravel and sand formations, characterized in that, include: S1. Real-time acquisition of the pressure value P of the jacking machine's hydraulic cylinder. c Calculate the current jacking force F c :F c =k1×P c ×A; S2, Synchronously acquire cutter head torque T and screw conveyor speed N s and excavation pressure P s Based on the coupling effect of gravel on the cutterhead and screw conveyor in the gravel strata, the relationship between T and N is calculated. s Mutation gradient M: M = ▽ (T / N) s When the abrupt change gradient M exceeds the preset threshold N, it is determined to be a zone of abrupt change in resistance of gravel strata; S3. When a zone of abrupt change in resistance is identified in gravel formations, dynamically predict the target formation resistance F. r :F r =F0+k2(MN); S4. Based on the current jacking force F c With the target formation resistance F r Real-time deviation value ΔF: ΔF = F c -F r Real-time adjustment of the jacking system: like If ΔF ≤ B, then maintain the current jacking parameters; if ΔF > B, then execute: decrease the jacking speed V and increase the grouting pressure P in conjunction. j Press N s =λ×V reduces the screw conveyor speed; if ΔF<-B, then execute: increase the jacking speed V, and simultaneously reduce the grouting pressure P. j Press N s =λ×V increases the speed of the screw conveyor; S5, P fed back by the grouting pressure sensor j Actual value, closed-loop control of the grouting pump output, making P j The jacking speed V satisfies: P j =f×V 0.5 Real-time data based on the excavation pressure P s Standard deviation σ s If σ s If the permeability coefficient is greater than σ0, it is determined to be a gravel formation with abnormal permeability. The permeability coefficient f' of the gravel formation is dynamically corrected as follows: f' = f + k3(σ s -σ0); Where A is the effective working area of ​​the hydraulic cylinder, in meters. 2 ; k1 is the system efficiency coefficient, obtained from the hydraulic cylinder no-load propulsion calibration test, with a value of 0.85~0.95; k2 is the particle size influence factor determined based on the gravel gradation, k2=0.3d 1.5 d. Maximum gravel size in the gravel layer, mm; F0 is the design reference resistance, in kN; λ is the soil removal efficiency coefficient for gravel strata, expressed in rpm·min / mm, and λ = Q / 1.4S, where Q is the theoretical discharge capacity of the screw conveyor, expressed in m³ / s. 3 / min; S is the cross-sectional area of ​​the pipe section, m 2 ; B is the resistance tolerance, in kN, and is taken as 5%~10% of F0; f is the permeability coefficient of the gravel formation; σ0 is the statistical value of the standard deviation of the excavation pressure in the test section of the homogeneous gravel formation, in MPa. k3 is the permeability correction factor, MPa -1 ·s -0.5 .

2. The real-time matching control method for pipe jacking force and formation resistance in gravel formations as described in claim 1, characterized in that, The permeability correction factor k3 was calibrated by performing the following operations during trial inference in gravel formations: fixing the jacking speed V at 20 mm / min; and adjusting the initial grouting pressure P... j0 Begin by gradually increasing the grouting pressure and recording the standard deviation σ of the soil pressure after each increase. s According to the formula = Calculate the values ​​for each working condition; take the arithmetic mean of k3 for each working condition as the final calibration value of k3.

3. The real-time matching control method for pipe jacking force and formation resistance in gravel formations as described in claim 2, characterized in that, In step S3, if the measured deviation value of the jacking force for three consecutive rings is... If the value is greater than 15%, then a dynamic correction of the particle size influence factor k2, determined based on the gravel gradation, is initiated: k2' = k2 + M i -N >0.1s -1 And F c,i -F0>50kN; where F c,i The pressure value of the inlet cylinder of the i-ring pipe jacking machine; M i For the i-th ring T and N s The mutation gradient.

4. The real-time matching control method for pipe jacking force and formation resistance in gravel formations as described in claim 3, characterized in that, In step S4, when the jacking pipe is in a curved section and the radius of curvature R < 500D, P j The relationship between P and the jacking speed V is corrected to: j =f×V 0.5 Where D is the outer diameter of the jacking pipe section, in meters; k4 is the curve segment compensation coefficient, with a value of 0.02θ, where θ is the axial deviation angle between pipe sections during curve jacking, in degrees.

5. The real-time matching control method for pipe jacking force and formation resistance in gravel formations as described in any one of claims 1 to 4, characterized in that, This also includes performing a friction reset operation every 100 rings: Pause jacking and maintain grouting pressure P j The pressure was 0.8 MPa for 5 minutes. The pipe section was slightly retracted by 20mm to release the interfacial shear stress; When restarting the jacking, the initial speed is reduced to 60% of the speed before the pause, and then resumed in steps of 10% / min.

6. The real-time matching control method for pipe jacking force and formation resistance in gravel formations as described in claim 4, characterized in that, Each corrected k2, k3, and f' are stored according to the classification of the ground-penetrating radar scan results; when the ground-penetrating radar identifies similar stratigraphic features, the historical optimal parameter combination is automatically called and preloaded.

7. The real-time matching control method for pipe jacking force and formation resistance in gravel formations as described in claim 6, characterized in that, The mechanism for obtaining the historical optimal parameter combination is as follows: Real-time acquisition of ground-penetrating radar scanning signals, extraction of characteristic signals of sand and gravel strata: dielectric constant ρ, reflection wave coefficient φ, and 0.2m scale reflectivity percentage P. 200 ; The effect evaluation function based on parameter combination is S=0.5× The parameter combination that minimizes S is the historically optimal parameter combination. When the radar identifies that the characteristic signals of the gravel strata are the same, it automatically loads the historical best parameter combination under the same gravel strata. The benchmark value for the jacking force fluctuation is the standard deviation of the jacking force in the trial push section.

8. The real-time matching control method for pipe jacking force and formation resistance in gravel formations as described in claim 1, characterized in that, If the cutterhead rotation speed fluctuation exceeds ±5% of the set value for 10 consecutive seconds, the target formation resistance prediction value in step S3 will be adjusted to F. r ':F r '=F r ×8%.

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