Safety prediction method and device for large-diameter pipe jacking construction in complex stratum

Abstract

The application provides a large-diameter pipe jacking construction safety prediction method and device for complex strata. In the soil layer drilling process, based on the water storage coefficient, the Mises stress and the seepage pressure gradient, the preset seepage stress coupling model is used to predict the predicted Mises stress of the pipe joint in the next prediction time period. Finally, different levels of safety warnings are issued based on the predicted Mises stress, and the pipe jacking construction system is controlled based on different levels of safety warnings to carry out sound wave suppression, injection of viscosity enhancer, and emergency shutdown and pipe joint glue injection operations to ensure that the soil layer drilling is stable. The scheme can accurately predict the seepage instability risk of the sand and gravel composite stratum, and avoids the problem that the prior art can only monitor the jacking force and settlement during the soil layer drilling process, and cannot warn the instantaneous seepage instability.

Description

Technical Field

[0001] This application relates to the field of soil drilling technology, specifically to a method and device for predicting the safety of large-diameter pipe jacking construction in complex strata. Background Technology

[0002] Pipe jacking is a trenchless underground pipeline laying technology. Its core lies in using jacking equipment to push the pipeline from a working shaft into the ground without large-scale surface excavation. Pipe jacking utilizes the thrust of the main jacking cylinder and intermediate jacking stations to push the pipeline into the ground at the designed slope, while simultaneously removing excavated soil. After each section of pipeline is pushed into the soil, the next section is advanced, continuing until the receiving shaft. The principle is that the jacking head breaks up the soil ahead, and then jacks push the pipeline forward. Special attention must be paid to safety during the drilling process in complex geological formations.

[0003] In water-rich sand and gravel composite strata (such as the alluvial deposits of the Yangtze River Delta), the permeability coefficients of the gravel layer and the sand layer differ greatly when the pipe jacking machine passes through (for example, the permeability coefficients of the gravel layer and the sand layer are 10 and 10, respectively). -2 cm / s and 10 -4 Groundwater flow (cm / s) creates dynamic seepage channels. When a local vacuum negative pressure is generated in front of the pipe jacking machine due to cutting disturbance, groundwater in the high-permeability gravel layer can suddenly rush into the low-permeability sand layer, causing instantaneous liquefaction of the sand layer (liquefaction index > 1.0). The soil strength in front of the pipe jacking can drop sharply by more than 90%. At this time, the thrust sensor of the pipe jacking machine shows a normal value (due to the reduced soil resistance in front), but undetected circumferential stress concentration has appeared in the pipe section behind (local stress > yield strength of Q345 steel 345MPa), ultimately leading to the bursting of the pipe joint. Existing technology in pipe jacking construction often only monitors the jacking force and settlement, but cannot provide early warning of instantaneous seepage instability. Summary of the Invention

[0004] This invention provides a method and apparatus for predicting the safety of large-diameter pipe jacking construction in complex geological formations. This method addresses the problem that existing technologies often only monitor the jacking force and settlement when drilling in sandy and gravelly composite formations rich in groundwater, but cannot provide early warnings of instantaneous seepage instability.

[0005] On one hand, this application provides a method for predicting the safety of large-diameter pipe jacking construction in complex geological formations. This method involves installing a microwave resonant sensor on the inner wall of the drilling fluid circulation pipeline, installing a fiber optic grating (FBG) array on the inner wall of each subsequently jacked pipe section, installing a first pore water pressure gauge array on the outer wall of each subsequently jacked pipe section, and radially installing a second pore water pressure gauge array in the soil layer at a predetermined distance in front of the pipe jacking head. The method includes:

[0006] During the drilling process in the soil layer, the water storage coefficient of the soil layer around the pipe section is obtained based on the drilling fluid density and yield stress collected by the microwave resonant sensor, the Mises stress of the pipe section is obtained based on the circumferential strain of the pipe section collected by the FBG array, and the seepage pressure gradient is obtained based on the measured values ​​of the first pore water pressure gauge array and the second pore water pressure gauge array.

[0007] Based on the water storage coefficient, Mises stress, and seepage pressure gradient, a pre-set seepage stress coupling model is used to predict the predicted Mises stress of the pipe section in the next prediction time period; wherein, the seepage stress coupling model indicates the relationship between the stress change rate and the seepage pressure gradient and the current stress under a specific water storage coefficient.

[0008] Based on the predicted Mises stress, different levels of safety warnings are issued, and based on the different levels of safety warnings, the pipe jacking construction system is controlled to perform sound wave suppression, injection of thickeners, and emergency shutdown and pipe section grouting operations to ensure that the drilling of the soil layer does not become unstable.

[0009] In one optional embodiment of this application, the method further includes: setting a ring-shaped acoustic wave emitting array at the front end of the pipe jacking machine head;

[0010] Based on different levels of safety early warning control, the pipe jacking construction system performs sound wave suppression, injection of adhesive, and emergency shutdown and pipe section grouting operations, including:

[0011] If the predicted Mises stress is greater than or equal to the first stress threshold and less than the second stress threshold, a first-level safety warning is issued, and the pipe jacking construction system is controlled to start the ring-shaped acoustic wave transmitting array to emit suppression acoustic waves to the soil layer in front.

[0012] If the predicted Mises stress is greater than or equal to the second stress threshold and less than the third stress threshold, a level two safety warning is issued, and the pipe jacking construction system is controlled to inject a viscosity modifier into the drilling fluid.

[0013] If the predicted Mises stress is greater than or equal to the third stress threshold, a level three safety warning will be issued, and the pipe jacking construction system will be shut down and adhesive will be injected into the pipe section behind the pipe jacking machine head.

[0014] Among them, the first stress threshold, the second stress threshold, and the third stress threshold increase sequentially, and the third stress threshold is the stress extreme value of the pipe section.

[0015] In one optional embodiment of this application, the first stress threshold is 250 MPa, the second stress threshold is 300 MPa, and the third stress threshold is 345 MPa.

[0016] The control system for pipe jacking construction activates a ring-shaped acoustic wave transmitting array to emit suppressive acoustic waves forward into the soil layer, including:

[0017] The ring-shaped acoustic wave transmitting array was controlled to transmit suppressed acoustic waves at a frequency of 100Hz to the soil layer in front with a power of 3kW until the second pore water pressure gauge array detected that the fluctuation amplitude of the seepage pressure in the soil layer in front was reduced by 40%.

[0018] The control of the pipe jacking system involves injecting a viscosifier into the drilling fluid, including:

[0019] The control pipe jacking construction system injects hydrolyzed polyacrylamide and nano-montmorillonite into the drilling fluid, such that the hydrolyzed polyacrylamide accounts for 0.4%-0.6% of the volume of the mixed drilling fluid, and the nano-montmorillonite accounts for 0.1%-0.2% of the volume of the mixed drilling fluid, until the microwave resonant sensor detects that the yield stress of the drilling fluid has increased to 150-200 Pa.

[0020] Controlling the shutdown of the pipe jacking construction system and injecting adhesive into the pipe section behind the pipe jacking machine head includes:

[0021] The pipe jacking construction system was shut down, and quick-setting epoxy resin was injected through the pre-embedded holes of the joints of the rear pipe sections until the FBG array detected that the circumferential stress had decreased to 300 MPa.

[0022] In one optional embodiment of this application, the method further includes:

[0023] Before construction begins, a preliminary seepage stress coupling model is constructed based on the physical mechanism of seepage pressure gradient driving stress change and water storage coefficient amplifying the current stress accumulation effect:

[0024] σ pred =σ vM +Δt(a▽P+bS s σ vM )

[0025] Where, σ pred To predict the Mises stress, σ vM Let S be the current Mises stress of the pipe section, ▽P be the seepage pressure gradient, and S be the pressure gradient of the seepage flow. s Δt is the water storage coefficient of the soil layer surrounding the pipe section, a is the seepage pressure influence coefficient, and b is the water storage coefficient coupling coefficient.

[0026] The coupling coefficients of the seepage pressure influence coefficient and the water storage coefficient are calibrated using historical engineering data to obtain a preset seepage stress coupling model.

[0027] Based on the water storage coefficient, Mises stress, and seepage pressure gradient, a pre-defined seepage stress coupling model is used to predict the predicted Mises stress of the pipe section within the prediction time period, including:

[0028] The water storage coefficient, Mises stress, and seepage pressure gradient are input into a preset seepage stress coupling model for calculation to obtain the corresponding predicted Mises stress.

[0029] In one optional embodiment of this application, the water storage coefficient of the soil layer surrounding the pipe section is obtained based on the drilling fluid density and yield stress collected by a microwave resonant sensor, including:

[0030] If the yield stress is greater than 80 Pa, then the water storage coefficient is determined to be 3 × 10⁻⁶. -5 m -1 ;

[0031] If the yield stress is not greater than 80 Pa, the water storage coefficient is determined by the following formula:

[0032]

[0033] Among them, S S E represents the water storage coefficient of the soil layer surrounding the pipe section. soil Let ρ be the elastic modulus of the soil, ρ be the density of the drilling fluid, g be the acceleration due to gravity, and τ be the acceleration due to gravity. y This represents the yield stress of the drilling fluid.

[0034] In one optional embodiment of this application, the Mises stress of the pipe section is obtained based on the circumferential strain acquired by the FBG array, using the following formula:

[0035]

[0036] Where, σ θ For the circumferential stress of the pipe section, σ r For the radial stress of the pipe section, σ z Let P be the axial stress of the pipe section, E be the elastic modulus of the pipe section, and P be the axial stress of the pipe section. W ε is the sum of earth pressure and water pressure. θ For the circumferential strain of the pipe section, σ vM Let be the current Mises stress of the pipe section, and v be the Poisson's ratio, taken as 0.3.

[0037] In one optional embodiment of this application, the seepage pressure gradient is obtained based on the measured values ​​of the first pore water pressure gauge array and the second pore water pressure gauge array, and is achieved by the following formula:

[0038]

[0039] in, P2 is the measured value of the second pore water pressure gauge array, P1 is the measured value of the first pore water pressure gauge array, and Δx is the radial distance between the second pore water pressure gauge array and the pipe jacking machine head, i.e., the preset distance.

[0040] Secondly, embodiments of this application provide a safety prediction device for large-diameter pipe jacking construction in complex geological formations. The device includes: a microwave resonant sensor installed on the inner wall of the drilling fluid circulation pipeline; a fiber optic grating (FBG) array installed on the inner wall of each subsequently jacked pipe section; a first pore water pressure gauge array installed on the outer wall of each subsequently jacked pipe section; and a second pore water pressure gauge array radially installed in the soil layer at a predetermined distance in front of the pipe jacking head; and:

[0041] The parameter acquisition module is used to obtain the water storage coefficient of the soil around the pipe section based on the drilling fluid density and yield stress collected by the microwave resonant sensor during the drilling process, obtain the Mises stress of the pipe section based on the circumferential strain collected by the FBG array, and obtain the seepage pressure gradient based on the measured values ​​of the first pore water pressure gauge array and the second pore water pressure gauge array.

[0042] The pipe section stress prediction module is used to predict the Mises stress of the pipe section in the next prediction time period based on the water storage coefficient, Mises stress and seepage pressure gradient, using a preset seepage stress coupling model; wherein, the seepage stress coupling model indicates the relationship between the stress change rate and the seepage pressure gradient and the current stress under a specific water storage coefficient.

[0043] The early warning and control module is used to issue different levels of safety warnings based on the predicted Mises stress, and to control the pipe jacking construction system to perform sound wave suppression, injection of thickener, and emergency shutdown and pipe section grouting operations based on the different levels of safety warnings, so as to ensure that the drilling of the soil layer does not become unstable.

[0044] In one optional embodiment of this application, a ring-shaped acoustic wave emitting array is provided at the front end of the pipe jacking machine head;

[0045] Based on different levels of safety early warning control, the pipe jacking construction system performs sound wave suppression, injection of adhesive, and emergency shutdown and pipe section grouting operations, including:

[0046] If the predicted Mises stress is greater than or equal to the first stress threshold and less than the second stress threshold, a first-level safety warning is issued, and the pipe jacking construction system is controlled to start the ring-shaped acoustic wave transmitting array to emit suppression acoustic waves to the soil layer in front.

[0047] If the predicted Mises stress is greater than or equal to the second stress threshold and less than the third stress threshold, a level two safety warning is issued, and the pipe jacking construction system is controlled to inject a viscosity modifier into the drilling fluid.

[0048] If the predicted Mises stress is greater than or equal to the third stress threshold, a level three safety warning will be issued, and the pipe jacking construction system will be shut down and adhesive will be injected into the pipe section behind the pipe jacking machine head.

[0049] Among them, the first stress threshold, the second stress threshold, and the third stress threshold increase sequentially, and the third stress threshold is the stress extreme value of the pipe section.

[0050] In one optional embodiment of this application, the first stress threshold is 250 MPa, the second stress threshold is 300 MPa, and the third stress threshold is 345 MPa.

[0051] The control system for pipe jacking construction activates a ring-shaped acoustic wave transmitting array to emit suppressive acoustic waves forward into the soil layer, including:

[0052] The ring-shaped acoustic wave transmitting array was controlled to transmit suppressed acoustic waves at a frequency of 100Hz to the soil layer in front with a power of 3kW until the second pore water pressure gauge array detected that the fluctuation amplitude of the seepage pressure in the soil layer in front was reduced by 40%.

[0053] The control of the pipe jacking system involves injecting a viscosifier into the drilling fluid, including:

[0054] The control pipe jacking construction system injects hydrolyzed polyacrylamide and nano-montmorillonite into the drilling fluid, such that the hydrolyzed polyacrylamide accounts for 0.4%-0.6% of the volume of the mixed drilling fluid, and the nano-montmorillonite accounts for 0.1%-0.2% of the volume of the mixed drilling fluid, until the microwave resonant sensor detects that the yield stress of the drilling fluid has increased to 150-200 Pa.

[0055] Controlling the shutdown of the pipe jacking construction system and injecting adhesive into the pipe section behind the pipe jacking machine head includes:

[0056] The pipe jacking construction system was shut down, and quick-setting epoxy resin was injected through the pre-embedded holes of the joints of the rear pipe sections until the FBG array detected that the circumferential stress had decreased to 300 MPa.

[0057] In one optional embodiment of this application, the device is further used for:

[0058] Before construction begins, a preliminary seepage stress coupling model is constructed based on the physical mechanism of seepage pressure gradient driving stress change and water storage coefficient amplifying the current stress accumulation effect:

[0059] σ pred =σ vM +Δt(a▽P+bS s σ vM )

[0060] Where, σ pred To predict the Mises stress, σ vM Let S be the current Mises stress of the pipe section, ▽P be the seepage pressure gradient, and S be the pressure gradient of the seepage flow. s Δt is the water storage coefficient of the soil layer surrounding the pipe section, a is the seepage pressure influence coefficient, and b is the water storage coefficient coupling coefficient.

[0061] The coupling coefficients of the seepage pressure influence coefficient and the water storage coefficient are calibrated using historical engineering data to obtain a preset seepage stress coupling model.

[0062] Based on the water storage coefficient, Mises stress, and seepage pressure gradient, a pre-defined seepage stress coupling model is used to predict the predicted Mises stress of the pipe section within the prediction time period, including:

[0063] The water storage coefficient, Mises stress, and seepage pressure gradient are input into a preset seepage stress coupling model for calculation to obtain the corresponding predicted Mises stress.

[0064] In one optional embodiment of this application, the water storage coefficient of the soil layer surrounding the pipe section is obtained based on the drilling fluid density and yield stress collected by a microwave resonant sensor, including:

[0065] If the yield stress is greater than 80 Pa, then the water storage coefficient is determined to be 3 × 10⁻⁶. -5 m -1 ;

[0066] If the yield stress is not greater than 80 Pa, the water storage coefficient is determined by the following formula:

[0067]

[0068] Among them, S S E represents the water storage coefficient of the soil layer surrounding the pipe section. soil Let ρ be the elastic modulus of the soil, ρ be the density of the drilling fluid, g be the acceleration due to gravity, and τ be the acceleration due to gravity. y This represents the yield stress of the drilling fluid.

[0069] In one optional embodiment of this application, the Mises stress of the pipe section is obtained based on the circumferential strain acquired by the FBG array, using the following formula:

[0070]

[0071] Where, σ θ For the circumferential stress of the pipe section, σ r For the radial stress of the pipe section, σ z Let P be the axial stress of the pipe section, E be the elastic modulus of the pipe section, and P be the axial stress of the pipe section. W ε is the sum of earth pressure and water pressure. θ For the circumferential strain of the pipe section, σ vM Let be the current Mises stress of the pipe section, and v be the Poisson's ratio, taken as 0.3.

[0072] In one optional embodiment of this application, the seepage pressure gradient is obtained based on the measured values ​​of the first pore water pressure gauge array and the second pore water pressure gauge array, and is achieved by the following formula:

[0073]

[0074] in, P2 is the measured value of the second pore water pressure gauge array, P1 is the measured value of the first pore water pressure gauge array, and Δx is the radial distance between the second pore water pressure gauge array and the pipe jacking machine head, i.e., the preset distance.

[0075] Thirdly, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements any of the above-described methods for predicting the safety of large-diameter pipe jacking construction in complex geological formations.

[0076] Fourthly, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described methods for predicting the safety of large-diameter pipe jacking construction in complex geological formations.

[0077] Fifthly, the present invention also provides a computer program product, including a computer program that, when executed by a processor, implements any of the above-described methods for predicting the safety of large-diameter pipe jacking construction in complex geological formations.

[0078] The solution provided in this application, during soil drilling, firstly obtains the water storage coefficient of the soil surrounding the pipe section based on the drilling fluid density and yield stress collected by a microwave resonant sensor; secondly, obtains the Mises stress of the pipe section based on the circumferential strain collected by an FBG array; and thirdly, obtains the seepage pressure gradient based on the measured values ​​of the first and second pore water pressure gauge arrays. Then, based on the water storage coefficient, Mises stress, and seepage pressure gradient, a preset seepage stress coupling model is used to predict the predicted Mises stress of the pipe section in the next prediction time period. Finally, based on the predicted Mises stress, different levels of safety warnings are issued, and the pipe jacking construction system is controlled to perform acoustic suppression, injection of viscosity enhancers, and emergency shutdown and pipe section adhesive injection operations based on these warnings to ensure that soil drilling does not become unstable. This solution can accurately predict seepage instability risks in sand and gravel composite formations, avoiding the problem of existing technologies that only monitor jacking force and settlement during soil drilling but cannot provide early warnings for instantaneous seepage instability. Attached Figure Description

[0079] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0080] Figure 1A flowchart illustrating a method for predicting the safety of large-diameter pipe jacking construction in complex geological formations, provided by this invention.

[0081] Figure 2 This is a flowchart illustrating the specific implementation of a method for predicting the safety of large-diameter pipe jacking construction in complex geological formations, as described in one embodiment of the invention.

[0082] Figure 3 This is a schematic diagram of the process for determining the water storage coefficient in one embodiment of the invention;

[0083] Figure 4 A structural block diagram of a safety prediction device for large-diameter pipe jacking construction in complex geological formations provided by the present invention;

[0084] Figure 5 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0085] In sand and gravel composite strata, the permeability coefficients of the sand and gravel layers differ by two orders of magnitude. The cutting disturbance from the pipe jacking machine head triggers a dynamic redistribution of multiphase fluids (groundwater, gas, and sand / gravel particles). Specifically, this includes abrupt changes in permeability coefficient, with the gravel layer permeability coefficient (k1 = 10) increasing dramatically. -2 The speed (cm / s) is much higher than that of the sand layer (k2=10). -4 The flow rate (cm / s) of the groundwater at the interface creates a high-speed seepage channel. During the cutting process of the pipe jacking machine, the gas in the pores of the gravel layer is instantly released, creating a local vacuum (negative pressure reaching -20 kPa), which causes pore water from the adsorbed sand layer to rapidly migrate towards the gravel layer. Sand liquefaction and stress abrupt changes occur, with the pore water pressure in the sand layer suddenly increasing, causing the effective stress to approach zero (liquefaction index L>1.0), resulting in a loss of soil shear strength. Simultaneously, the circumferential stress of the pipe section rapidly concentrates due to soil support failure, exceeding the yield strength of the steel. In this situation, the thrust sensor of the pipe jacking machine head shows a normal value (due to reduced soil resistance ahead), but undetected circumferential stress concentration (local stress > Q345 steel yield strength 345 MPa) has appeared in the rear pipe section, ultimately leading to the pipe joint bursting. To address these issues, this application proposes a safety prediction scheme for large-diameter pipe jacking construction in complex strata. The scheme will be described in detail below.

[0086] Figure 1 A flowchart illustrating a method for predicting the safety of large-diameter pipe jacking construction in complex geological formations, as provided in this application embodiment, is shown below. Figure 1 As shown.

[0087] First, a microwave resonant sensor is installed on the inner wall of the drilling fluid circulation pipeline, a fiber optic grating (FBG) array is installed on the inner wall of each subsequent jacking pipe section, a first pore water pressure gauge array is installed on the outer wall of each subsequent jacking pipe section, and a second pore water pressure gauge array is radially installed in the soil layer at a predetermined distance in front of the pipe jacking head.

[0088] It should be noted that the embodiments of this application take Q345 steel as an example for illustration. When the pipe section material is other materials, the solution can also be adjusted and applied. This application is not limited to this.

[0089] Specifically, in order to achieve automatic control, automatic safety warning, and automatic anti-instability operation for soil drilling, in addition to the aforementioned sensors, this application embodiment also includes a central control unit for processing and analyzing the data collected by the sensors, issuing warnings based on the processing results according to the scheme provided in this application embodiment, and further issuing anti-instability instructions according to the scheme provided in this application embodiment, thereby ensuring the automation of the entire soil drilling process.

[0090] Specifically, a microwave resonant sensor is installed on the inner wall of the drilling fluid circulation pipeline, positioned 1 meter from the grouting port, to collect data such as drilling fluid density and yield stress at a frequency of 2.4-2.5 GHz. A fiber optic grating (FBG) array is installed on the inner wall of each subsequent jacking section, with eight points evenly distributed circumferentially on each section's inner wall to collect circumferential strain, with a strain measurement range of ±5000 με. A first pore water pressure gauge array is installed on the outer wall of each subsequent jacking section. Fiber optic grating pore water pressure gauges can be used, with four measuring points (0°, 90°, 180°, 270°) arranged circumferentially along the outer wall of the section, each 10 cm from the pipe wall. During data acquisition, the sampling rate can be set to 10 Hz. The fiber optic signal is transmitted to the central control unit at the ground control center via a pre-embedded line in the section. The average value of the four measuring points is taken as the pore water pressure around the pipe, i.e., the measured value of the first pore water pressure gauge. A second pore water pressure gauge array is radially installed in the soil layer at a preset distance in front of the pipe jacking machine head. It can be arranged in a ring along the radial direction of the pipe jacking machine head (perpendicular to the jacking direction), with a total of 6 measuring points, evenly distributed at 60° intervals. Each measuring point is buried 1.5 meters in the stratum (in the sand and gravel stratum, it needs to penetrate the gravel layer to enter the sand layer). The sampling rate can be set to 10Hz.

[0091] In addition, a ring-shaped acoustic wave emitting array is set at the front end of the pipe jacking machine head, 0.5m away from the cutterhead, with a frequency range of 100Hz-10kHz (programmable sweep frequency) and a power of 1-5kW (adjustable in 8 levels), used to emit suppressive acoustic waves forward to the soil layer.

[0092] Based on the above settings, the method of this application may include:

[0093] Step S101: During the drilling process, the water storage coefficient of the soil layer around the pipe section is obtained based on the drilling fluid density and yield stress collected by the microwave resonant sensor, the Mises stress of the pipe section is obtained based on the circumferential strain of the pipe section collected by the FBG array, and the seepage pressure gradient is obtained based on the measured values ​​of the first pore water pressure gauge array and the second pore water pressure gauge array.

[0094] Specifically, during the pipe jacking process, key parameters of the interaction between the formation, structure, and fluids are acquired in real time through multi-sensor collaborative monitoring. In practice, three sets of microwave resonant sensors are first installed circumferentially at equal intervals on the inner wall of the drilling fluid circulation pipeline behind the pipe jacking head. The operating frequency band is set to 2.4-2.5 GHz, and the density and yield stress of the drilling fluid are continuously collected at a sampling rate of 200 Hz. The phase shift and amplitude attenuation characteristics of the microwave signal in the slurry can be dynamically analyzed using a pre-calibrated rheological model to deduce the dynamic yield stress value of the drilling fluid. This value is then combined with the density parameter to match the water storage coefficient from a built-in empirical database. This database can be optimized in real time based on bentonite concentration and formation permeability classification parameters to ensure the adaptability of the water storage coefficient to the current operating conditions.

[0095] Meanwhile, eight fiber optic grating (FBG) measurement points are evenly distributed circumferentially on the inner wall of each prefabricated pipe section, with a 45° interval between the measurement points. Each measurement point integrates a temperature compensation module to eliminate environmental thermal disturbances. The real-time acquired circumferential strain data is converted into circumferential stress through the pipe's elastic modulus and Poisson's ratio. Combined with the pipe section's geometric parameters and stress boundary conditions, the radial and axial stress components are derived. Finally, based on the fourth strength theory, the Mises stress is calculated by integrating triaxial stress to accurately characterize the overall yield risk of the pipe section.

[0096] To reconstruct the seepage pressure gradient, a radial second array of pore water pressure (4 measuring points) is arranged 3 meters in front of the pipe jacking machine head to monitor the water pressure field in the advancing direction in real time. At the same time, a first array of pore water pressure can be set at 1-meter intervals on the outer wall of the pipe section. The water pressure distribution around the pipe can be generated by spatial interpolation and surface fitting. The intensity of non-uniform groundwater flow is quantified by the finite difference method to obtain the seepage pressure gradient.

[0097] All sensor data are synchronized at the microsecond level via Precise Time Protocol (PTP) and embedded with quality control algorithms: microwave data is filtered by sliding window mean to eliminate slurry bubble interference; fiber optic strain signals are denoised by wavelet thresholding to suppress high-frequency components of mechanical vibration; and pore water pressure data undergoes consistency verification (manual review is triggered when the difference between adjacent measuring points exceeds 20 kPa). The final output includes three core parameters: the water storage coefficient of the soil surrounding the pipe section, the Mises stress of the pipe section, and the seepage pressure gradient, providing high-confidence input for subsequent seepage-stress coupling models.

[0098] In addition to microwave resonant sensing, the water storage coefficient can also be indirectly calibrated through the dynamic response of soil compressibility. A miniature pressure pulse generator is placed in front of the pipe jacking machine head to emit controllable pressure waves into the soil layer at a frequency of 1-5Hz. Simultaneously, distributed optical fiber acoustic sensing (DAS) is used to capture the propagation velocity and attenuation characteristics of the pressure waves. The pressure wave velocity is positively correlated with the soil compressibility modulus. Combined with the transient response curve of pore water pressure, the contributions of soil skeleton compression and fluid release are separated through an inversion algorithm to dynamically calculate the water storage coefficient.

[0099] Step S102: Based on the water storage coefficient, Mises stress, and seepage pressure gradient, the predicted Mises stress of the pipe section in the next prediction time period is predicted using a preset seepage stress coupling model; wherein, the seepage stress coupling model indicates the relationship between the stress change rate and the seepage pressure gradient and the current stress under a specific water storage coefficient.

[0100] Specifically, this step achieves advanced prediction of the mechanical state of the pipe section by constructing a coupling relationship model between transient seepage and joint stress. In practice, the water storage coefficient, real-time Mises stress, and seepage pressure gradient extracted in step S101 are input into a preset seepage-stress coupling model. This model, based on the constitutive relationship between soil compression and water release effects and the elastoplastic deformation of the pipe section, establishes a two-way mechanism of seepage-driven stress accumulation and stress feedback-regulated seepage. In the model, the stress change rate is represented as the seepage pressure gradient and the current stress, where the seepage pressure gradient dominates the short-term stress surge, and the product of the water storage coefficient and the current stress reflects the amplification effect of long-term soil creep on structural fatigue.

[0101] For example, during the prediction process, the model iterates in 50-millisecond time steps: first, it calculates the instantaneous load increment of groundwater on the pipe section based on the current seepage pressure gradient; then, it corrects the hysteretic response of soil deformation under load by incorporating the water storage coefficient; finally, it outputs the evolution curve and peak predicted value of the Mises stress within the next 10 seconds by constraining the hardening criterion and damage threshold of the pipe section material. To enhance adaptability to different working conditions, the deviation between the predicted Mises stress and the measured FBG value can be compared in real time. When the error exceeds 5%, the model parameter correction is automatically triggered to ensure prediction robustness.

[0102] Step S103: Based on the predicted Mises stress, issue different levels of safety warnings, and based on the different levels of safety warnings, control the pipe jacking construction system to perform sound wave suppression, inject adhesive, and perform emergency shutdown and pipe section grouting operations to ensure that the drilling of the soil layer does not become unstable.

[0103] Specifically, this step involves constructing a three-tiered, progressive safety early warning system based on predicted Mises stress, which is then linked to the pipe jacking construction system to achieve risk-level intervention. For example:

[0104] When the predicted Mises stress value triggers a Level 1 safety warning (250-300 MPa), the system immediately activates the ring-shaped acoustic wave transmitting array, directionally radiating the soil layer ahead in a 100Hz low-frequency continuous wave mode (3kW power, 500ms pulse width). The acoustic energy is focused on the sand-gravel interface, disrupting the capillary water film structure and reorganizing the particle skeleton, reducing the liquefaction index to below 0.7 and decreasing the seepage velocity by 60%. Simultaneously, the second pore water pressure gauge array monitors the pore water pressure fluctuations in the sand layer in real time. When the pressure drop reaches 30 kPa, it switches to an intermittent emission mode (50% duty cycle) to avoid excessive disturbance to the formation.

[0105] If the Mises stress is predicted to trigger a level 2 safety warning (300-345MPa), the system will simultaneously perform drilling fluid rheological property control: in the grouting ring behind the drill head, a composite thickener of nano-montmorillonite and polyacrylamide is injected at a flow rate of 8L / min to increase the yield stress of the drilling fluid to 180Pa, forming a shear thickening barrier.

[0106] When the predicted Mises stress triggers a Level 3 safety warning (≥345MPa), the system cuts off the hydraulic propulsion power within 50ms and initiates the pipe section injection emergency procedure. Six sets of injection holes pre-embedded in the pipe section joint are sprayed with fast-setting epoxy resin (curing time ≤15s) at a pressure of 1.2MPa, achieving radial penetration and filling along the gap between the pipe section and the soil, forming a circumferential reinforcement layer.

[0107] The solution provided in this application, during soil drilling, firstly obtains the water storage coefficient of the soil surrounding the pipe section based on the drilling fluid density and yield stress collected by a microwave resonant sensor; secondly, obtains the Mises stress of the pipe section based on the circumferential strain collected by an FBG array; and thirdly, obtains the seepage pressure gradient based on the measured values ​​of the first and second pore water pressure gauge arrays. Then, based on the water storage coefficient, Mises stress, and seepage pressure gradient, a preset seepage stress coupling model is used to predict the predicted Mises stress of the pipe section in the next prediction time period. Finally, based on the predicted Mises stress, different levels of safety warnings are issued, and the pipe jacking construction system is controlled to perform acoustic suppression, injection of viscosity enhancers, and emergency shutdown and pipe section adhesive injection operations based on these warnings to ensure that soil drilling does not become unstable. This solution can accurately predict seepage instability risks in sand and gravel composite formations, avoiding the problem of existing technologies that only monitor jacking force and settlement during soil drilling but cannot provide early warnings for instantaneous seepage instability.

[0108] In one optional embodiment of this application, the method further includes: setting a ring-shaped acoustic wave emitting array at the front end of the pipe jacking machine head;

[0109] Based on different levels of safety early warning control, the pipe jacking construction system performs sound wave suppression, injection of adhesive, and emergency shutdown and pipe section grouting operations, including:

[0110] If the predicted Mises stress is greater than or equal to the first stress threshold and less than the second stress threshold, a first-level safety warning is issued, and the pipe jacking construction system is controlled to start the ring-shaped acoustic wave transmitting array to emit suppression acoustic waves to the soil layer in front.

[0111] If the predicted Mises stress is greater than or equal to the second stress threshold and less than the third stress threshold, a level two safety warning is issued, and the pipe jacking construction system is controlled to inject a viscosity modifier into the drilling fluid.

[0112] If the predicted Mises stress is greater than or equal to the third stress threshold, a level three safety warning will be issued, and the pipe jacking construction system will be shut down and adhesive will be injected into the pipe section behind the pipe jacking machine head.

[0113] Among them, the first stress threshold, the second stress threshold, and the third stress threshold increase sequentially, and the third stress threshold is the stress extreme value of the pipe section.

[0114] Specifically, such as Figure 2 As shown, the first stress threshold is 250 MPa, the second stress threshold is 300 MPa, and the third stress threshold is 345 MPa.

[0115] The control system for pipe jacking construction activates a ring-shaped acoustic wave transmitting array to emit suppressive acoustic waves forward into the soil layer, including:

[0116] The ring-shaped acoustic wave transmitting array was controlled to transmit suppressed acoustic waves at a frequency of 100Hz to the soil layer in front with a power of 3kW until the second pore water pressure gauge array detected that the fluctuation amplitude of the seepage pressure in the soil layer in front was reduced by 40%.

[0117] The control of the pipe jacking system involves injecting a viscosifier into the drilling fluid, including:

[0118] The control pipe jacking construction system injects hydrolyzed polyacrylamide and nano-montmorillonite into the drilling fluid, such that the hydrolyzed polyacrylamide accounts for 0.4%-0.6% of the volume of the mixed drilling fluid, and the nano-montmorillonite accounts for 0.1%-0.2% of the volume of the mixed drilling fluid, until the microwave resonant sensor detects that the yield stress of the drilling fluid has increased to 150-200 Pa.

[0119] Controlling the shutdown of the pipe jacking construction system and injecting adhesive into the pipe section behind the pipe jacking machine head includes:

[0120] The pipe jacking construction system was shut down, and quick-setting epoxy resin was injected through the pre-embedded holes of the joints of the rear pipe sections until the FBG array detected that the circumferential stress had decreased to 300 MPa.

[0121] The first-level warning indicates that a seepage channel has initially formed, with a localized risk of sand liquefaction (liquefaction index L = 0.6-0.8), requiring suppression of liquefaction development. The second-level warning indicates that the stress in the pipe section is approaching its yield strength (70%-90%), seepage is accelerating, and may cause pipe section deformation. The third-level warning indicates that the pipe section has entered the plastic deformation stage, seepage is out of control, and there is a possibility of bursting at any time, requiring an emergency shutdown.

[0122] In one optional embodiment of this application, the method further includes:

[0123] Before construction begins, a preliminary seepage stress coupling model is constructed based on the physical mechanism of seepage pressure gradient driving stress change and water storage coefficient amplifying the current stress accumulation effect:

[0124] σ pred =σ vM +Δt(a▽P+bS s σ vM )

[0125] Where, σ pred To predict the Mises stress, σ vM Let S be the current Mises stress of the pipe section, ▽P be the seepage pressure gradient, and S be the pressure gradient of the seepage flow. s Δt is the water storage coefficient of the soil layer surrounding the pipe section, a is the seepage pressure influence coefficient, and b is the water storage coefficient coupling coefficient.

[0126] The coupling coefficients of the seepage pressure influence coefficient and the water storage coefficient are calibrated using historical engineering data to obtain a preset seepage stress coupling model.

[0127] Based on the water storage coefficient, Mises stress, and seepage pressure gradient, a pre-defined seepage stress coupling model is used to predict the predicted Mises stress of the pipe section within the prediction time period, including:

[0128] The water storage coefficient, Mises stress, and seepage pressure gradient are input into a preset seepage stress coupling model for calculation to obtain the corresponding predicted Mises stress.

[0129] Historical engineering data: Complete monitoring data from 20 pipe jacking soil drilling projects in similar geological formations were selected, including σ vM P, S s And the actual stress change rate. In the calibration process, the objective function is constructed to minimize the sum of squared prediction errors, and linear regression is used to solve for the final calibration results, namely the seepage pressure influence coefficient 'a' and the water storage coefficient coupling coefficient 'b', to ensure the model's formation adaptability.

[0130] In one optional embodiment of this application, the water storage coefficient of the soil layer surrounding the pipe section is obtained based on the drilling fluid density and yield stress collected by a microwave resonant sensor, including:

[0131] If the yield stress is greater than 80 Pa, then the water storage coefficient is determined to be 3 × 10⁻⁶. -5 m -1 ;

[0132] If the yield stress is not greater than 80 Pa, the water storage coefficient is determined by the following formula:

[0133]

[0134] Among them, S S E represents the water storage coefficient of the soil layer surrounding the pipe section. soil Let ρ be the elastic modulus of the soil, ρ be the density of the drilling fluid, g be the acceleration due to gravity, and τ be the acceleration due to gravity. y This represents the yield stress of the drilling fluid.

[0135] Specifically, such as Figure 3 As shown, when the yield stress is greater than 80 Pa, the water storage coefficient is directly determined to be 3 × 10⁻⁶. -5 m -1 This is to ensure that the model does not diverge.

[0136] In one optional embodiment of this application, the Mises stress of the pipe section is obtained based on the circumferential strain acquired by the FBG array, using the following formula:

[0137]

[0138] Where, σ θ For the circumferential stress of the pipe section, σ r For the radial stress of the pipe section, σ z Let P be the axial stress of the pipe section, E be the elastic modulus of the pipe section, and P be the axial stress of the pipe section. W ε is the sum of earth pressure and water pressure. θ For the circumferential strain of the pipe section, σ vM Let be the current Mises stress of the pipe section, and v be the Poisson's ratio, taken as 0.3.

[0139] In one optional embodiment of this application, the seepage pressure gradient is obtained based on the measured values ​​of the first pore water pressure gauge array and the second pore water pressure gauge array, and is achieved by the following formula:

[0140]

[0141] in, P2 is the measured value of the second pore water pressure gauge array, P1 is the measured value of the first pore water pressure gauge array, and Δx is the radial distance between the second pore water pressure gauge array and the pipe jacking machine head, i.e., the preset distance.

[0142] Figure 4A structural block diagram of a safety prediction device for large-diameter pipe jacking construction in complex geological formations provided in this application embodiment is shown below. Figure 4 As shown.

[0143] The device includes: a microwave resonant sensor installed on the inner wall of the drilling fluid circulation pipeline; a fiber optic grating (FBG) array installed on the inner wall of each subsequently jacked pipe section; a first pore water pressure gauge array installed on the outer wall of each subsequently jacked pipe section; and a second pore water pressure gauge array radially installed in the soil layer at a predetermined distance in front of the pipe jacking head; and:

[0144] The parameter acquisition module 201 is used to obtain the water storage coefficient of the soil around the pipe section based on the drilling fluid density and yield stress collected by the microwave resonant sensor during the drilling process, obtain the Mises stress of the pipe section based on the circumferential strain collected by the FBG array, and obtain the seepage pressure gradient based on the measured values ​​of the first pore water pressure gauge array and the second pore water pressure gauge array.

[0145] The pipe section stress prediction module 202 is used to predict the predicted Mises stress of the pipe section in the next prediction time period based on the water storage coefficient, Mises stress and seepage pressure gradient using a preset seepage stress coupling model; wherein, the seepage stress coupling model indicates the relationship between the stress change rate and the seepage pressure gradient and the current stress under a specific water storage coefficient.

[0146] The early warning and control module 203 is used to issue different levels of safety warnings based on the predicted Mises stress, and to control the pipe jacking construction system to perform sound wave suppression, injection of adhesive, and emergency shutdown and pipe section grouting operations based on the different levels of safety warnings, so as to ensure that the drilling of the soil layer does not become unstable.

[0147] The solution provided in this application, during soil drilling, firstly obtains the water storage coefficient of the soil surrounding the pipe section based on the drilling fluid density and yield stress collected by a microwave resonant sensor; secondly, obtains the Mises stress of the pipe section based on the circumferential strain collected by an FBG array; and thirdly, obtains the seepage pressure gradient based on the measured values ​​of the first and second pore water pressure gauge arrays. Then, based on the water storage coefficient, Mises stress, and seepage pressure gradient, a preset seepage stress coupling model is used to predict the predicted Mises stress of the pipe section in the next prediction time period. Finally, based on the predicted Mises stress, different levels of safety warnings are issued, and the pipe jacking construction system is controlled to perform acoustic suppression, injection of viscosity enhancers, and emergency shutdown and pipe section adhesive injection operations based on these warnings to ensure that soil drilling does not become unstable. This solution can accurately predict seepage instability risks in sand and gravel composite formations, avoiding the problem of existing technologies that only monitor jacking force and settlement during soil drilling but cannot provide early warnings for instantaneous seepage instability.

[0148] In one optional embodiment of this application, a ring-shaped acoustic wave emitting array is set at the front end of the pipe jacking machine head. Based on different levels of safety early warning control, the pipe jacking construction system performs acoustic wave suppression, injection of adhesive, and emergency shutdown and pipe section glue injection operations, including:

[0149] If the predicted Mises stress is greater than or equal to the first stress threshold and less than the second stress threshold, a first-level safety warning is issued, and the pipe jacking construction system is controlled to start the ring-shaped acoustic wave transmitting array to emit suppression acoustic waves to the soil layer in front.

[0150] If the predicted Mises stress is greater than or equal to the second stress threshold and less than the third stress threshold, a level two safety warning is issued, and the pipe jacking construction system is controlled to inject a viscosity modifier into the drilling fluid.

[0151] If the predicted Mises stress is greater than or equal to the third stress threshold, a level three safety warning will be issued, and the pipe jacking construction system will be shut down and adhesive will be injected into the pipe section behind the pipe jacking machine head.

[0152] Among them, the first stress threshold, the second stress threshold, and the third stress threshold increase sequentially, and the third stress threshold is the stress extreme value of the pipe section.

[0153] In one optional embodiment of this application, the first stress threshold is 250 MPa, the second stress threshold is 300 MPa, and the third stress threshold is 345 MPa.

[0154] The control system for pipe jacking construction activates a ring-shaped acoustic wave transmitting array to emit suppressive acoustic waves forward into the soil layer, including:

[0155] The ring-shaped acoustic wave transmitting array was controlled to transmit suppressed acoustic waves at a frequency of 100Hz to the soil layer in front with a power of 3kW until the second pore water pressure gauge array detected that the fluctuation amplitude of the seepage pressure in the soil layer in front was reduced by 40%.

[0156] The control of the pipe jacking system involves injecting a viscosifier into the drilling fluid, including:

[0157] The control pipe jacking construction system injects hydrolyzed polyacrylamide and nano-montmorillonite into the drilling fluid, such that the hydrolyzed polyacrylamide accounts for 0.4%-0.6% of the volume of the mixed drilling fluid, and the nano-montmorillonite accounts for 0.1%-0.2% of the volume of the mixed drilling fluid, until the microwave resonant sensor detects that the yield stress of the drilling fluid has increased to 150-200 Pa.

[0158] Controlling the shutdown of the pipe jacking construction system and injecting adhesive into the pipe section behind the pipe jacking machine head includes:

[0159] The pipe jacking construction system was shut down, and quick-setting epoxy resin was injected through the pre-embedded holes of the joints of the rear pipe sections until the FBG array detected that the circumferential stress had decreased to 300 MPa.

[0160] In one optional embodiment of this application, the device is further used for:

[0161] Before construction begins, a preliminary seepage stress coupling model is constructed based on the physical mechanism of seepage pressure gradient driving stress change and water storage coefficient amplifying the current stress accumulation effect:

[0162] σ pred =σ vM +Δt(a▽P+bS s σ vM )

[0163] Where, σ pred To predict the Mises stress, σ vM Let S be the current Mises stress of the pipe section, ▽P be the seepage pressure gradient, and S be the pressure gradient of the seepage flow. s Δt is the water storage coefficient of the soil layer surrounding the pipe section, a is the seepage pressure influence coefficient, and b is the water storage coefficient coupling coefficient.

[0164] The coupling coefficients of the seepage pressure influence coefficient and the water storage coefficient are calibrated using historical engineering data to obtain a preset seepage stress coupling model.

[0165] Based on the water storage coefficient, Mises stress, and seepage pressure gradient, a pre-defined seepage stress coupling model is used to predict the predicted Mises stress of the pipe section within the prediction time period, including:

[0166] The water storage coefficient, Mises stress, and seepage pressure gradient are input into a preset seepage stress coupling model for calculation to obtain the corresponding predicted Mises stress.

[0167] In one optional embodiment of this application, the water storage coefficient of the soil layer surrounding the pipe section is obtained based on the drilling fluid density and yield stress collected by a microwave resonant sensor, including:

[0168] If the yield stress is greater than 80 Pa, then the water storage coefficient is determined to be 3 × 10⁻⁶. -5 m -1 ;

[0169] If the yield stress is not greater than 80 Pa, the water storage coefficient is determined by the following formula:

[0170]

[0171] Among them, S S E represents the water storage coefficient of the soil layer surrounding the pipe section. soil Let ρ be the elastic modulus of the soil, ρ be the density of the drilling fluid, g be the acceleration due to gravity, and τ be the acceleration due to gravity. y This represents the yield stress of the drilling fluid.

[0172] In one optional embodiment of this application, the Mises stress of the pipe section is obtained based on the circumferential strain acquired by the FBG array, using the following formula:

[0173]

[0174] Where, σ θ For the circumferential stress of the pipe section, σ r For the radial stress of the pipe section, σ z Let P be the axial stress of the pipe section, E be the elastic modulus of the pipe section, and P be the axial stress of the pipe section. W ε is the sum of earth pressure and water pressure. θ For the circumferential strain of the pipe section, σ vM Let be the current Mises stress of the pipe section, and v be the Poisson's ratio, taken as 0.3.

[0175] In one optional embodiment of this application, the seepage pressure gradient is obtained based on the measured values ​​of the first pore water pressure gauge array and the second pore water pressure gauge array, and is achieved by the following formula:

[0176]

[0177] in, P2 is the measured value of the second pore water pressure gauge array, P1 is the measured value of the first pore water pressure gauge array, and Δx is the radial distance between the second pore water pressure gauge array and the pipe jacking machine head, i.e., the preset distance.

[0178] Figure 5 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 5As shown, the electronic device may include: a processor 310, a communication interface 320, a memory 330, and a communication bus 340. The processor 310, communication interface 320, and memory 330 communicate with each other via the communication bus 340. The processor 310 can call logical instructions in the memory 330 to execute a safety prediction method for large-diameter pipe jacking construction in complex geological formations. This method includes: installing a microwave resonant sensor on the inner wall of the drilling fluid circulation pipeline; installing a fiber optic grating (FBG) array on the inner wall of each subsequently jacked pipe section; installing a first pore water pressure gauge array on the outer wall of each subsequently jacked pipe section; and radially installing a second pore water pressure gauge array in the soil layer at a predetermined distance in front of the pipe jacking head. During the soil drilling process, the water storage coefficient of the soil layer surrounding the pipe section is obtained based on the drilling fluid density and yield stress collected by the microwave resonant sensor, and the Mises stress of the pipe section is obtained based on the circumferential strain of the pipe section collected by the FBG array. The system obtains the seepage pressure gradient based on the measured values ​​of the first and second pore water pressure gauge arrays. Based on the storage coefficient, Mises stress, and seepage pressure gradient, a preset seepage stress coupling model is used to predict the predicted Mises stress of the pipe section in the next prediction time period. The seepage stress coupling model indicates the relationship between the stress change rate, seepage pressure gradient, and current stress under a specific storage coefficient. Based on the predicted Mises stress, different levels of safety warnings are issued, and based on the different levels of safety warnings, the pipe jacking construction system is controlled to perform sound wave suppression, injection of thickener, and emergency shutdown and pipe section grouting operations to ensure that the soil drilling does not become unstable.

[0179] Furthermore, the logical instructions in the aforementioned memory 330 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0180] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the safety prediction method for large-diameter pipe jacking construction in complex formations provided by the above methods. The method includes: setting a microwave resonant sensor on the inner wall of the drilling fluid circulation pipeline, setting a fiber optic grating (FBG) array on the inner wall of each subsequently jacked pipe section, setting a first pore water pressure gauge array on the outer wall of each subsequently jacked pipe section, and radially setting a second pore water pressure gauge array in the soil layer at a predetermined distance in front of the pipe jacking head; during the soil drilling process, obtaining the drilling fluid density and yield stress around the pipe section based on the data collected by the microwave resonant sensor. The water storage coefficient of the soil layer is used to obtain the Mises stress of the pipe section based on the circumferential strain collected by the FBG array, and the seepage pressure gradient is obtained based on the measured values ​​of the first and second pore water pressure gauge arrays. Based on the water storage coefficient, Mises stress, and seepage pressure gradient, the predicted Mises stress of the pipe section in the next prediction time period is predicted using a preset seepage stress coupling model. The seepage stress coupling model indicates the relationship between the stress change rate, seepage pressure gradient, and current stress under a specific water storage coefficient. Based on the predicted Mises stress, different levels of safety warnings are issued, and based on the different levels of safety warnings, the pipe jacking construction system is controlled to perform sound wave suppression, injection of thickener, and emergency shutdown and pipe section glue injection operations to ensure that the drilling of the soil layer does not become unstable.

[0181] Furthermore, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon. When executed by a processor, the computer program implements the safety prediction method for large-diameter pipe jacking construction in complex geological formations provided by the methods described above. This method includes: installing a microwave resonant sensor on the inner wall of the drilling fluid circulation pipeline; installing a fiber optic grating (FBG) array on the inner wall of each subsequently jacked pipe section; installing a first pore water pressure gauge array on the outer wall of each subsequently jacked pipe section; and radially installing a second pore water pressure gauge array in the soil layer at a predetermined distance in front of the pipe jacking head. During drilling in the soil layer, the water storage coefficient of the soil layer surrounding the pipe section is obtained based on the drilling fluid density and yield stress collected by the microwave resonant sensor, and the water storage coefficient is determined based on the FBG array... The circumferential strain of the pipe section is collected to obtain the Mises stress of the pipe section. The seepage pressure gradient is obtained based on the measured values ​​of the first and second pore water pressure gauge arrays. Based on the water storage coefficient, Mises stress, and seepage pressure gradient, a preset seepage stress coupling model is used to predict the predicted Mises stress of the pipe section in the next prediction time period. The seepage stress coupling model indicates the relationship between the stress change rate, seepage pressure gradient, and current stress under a specific water storage coefficient. Based on the predicted Mises stress, different levels of safety warnings are issued, and based on the different levels of safety warnings, the pipe jacking construction system is controlled to perform sound wave suppression, injection of thickener, and emergency shutdown and pipe section glue injection operations to ensure that the drilling of the soil layer does not become unstable.

[0182] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0183] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0184] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A large-diameter pipe jacking construction safety prediction method for complex strata, characterized by, The method comprises the following steps: During the soil drilling process, the water storage coefficient of the soil around the pipe section is obtained based on the drilling fluid density and the yield stress collected by the microwave resonance sensor, the Mises stress of the pipe section is obtained based on the circumferential strain of the pipe section collected by the FBG array, and the seepage pressure gradient is obtained based on the measured values of the first pore water pressure gauge array and the second pore water pressure gauge array; Based on the water storage coefficient, the Mises stress, and the seepage pressure gradient, a preset seepage stress coupling model is used to predict the predicted Mises stress of the pipe section in the next prediction time period; wherein the seepage stress coupling model indicates the relationship between the stress change rate and the seepage pressure gradient and the current stress under a specific water storage coefficient; Based on the predicted Mises stress, different levels of safety warnings are issued, and the pipe jacking construction system is controlled based on different levels of safety warnings to perform sound wave suppression, injection of viscosity enhancer, and emergency shutdown and pipe section glue injection operations to ensure that the soil drilling is stable; The method further comprises the following steps: Before the construction starts, a preliminary seepage stress coupling model is constructed based on the physical mechanism that the seepage pressure gradient drives the stress change and the water storage coefficient amplifies the current stress accumulation effect; wherein, is the predicted Misess stress, is the current Misess stress of the pipe section, is the seepage pressure gradient, is the storage coefficient of the soil surrounding the pipe section, is the prediction time period, is the seepage pressure influence coefficient, is the storage coefficient coupling coefficient; The seepage pressure influence coefficient and the water storage coefficient coupling coefficient are calibrated through historical engineering data to obtain the preset seepage stress coupling model; The method further comprises the following steps: The water storage coefficient, the Mises stress, and the seepage pressure gradient are input into the preset seepage stress coupling model for calculation to obtain the corresponding predicted Mises stress.

2. The method of claim 1, wherein, The method further comprises the following steps: The method further comprises the following steps: If the predicted Mises stress is greater than or equal to the first stress threshold and less than the second stress threshold, a first-level safety warning is issued, and the pipe jacking construction system is controlled to start the annular sound wave emission array to emit inhibitory sound waves to the front soil layer; If the predicted Mises stress is greater than or equal to the second stress threshold and less than the third stress threshold, a second-level safety warning is issued, and the pipe jacking construction system is controlled to inject viscosity enhancer into the drilling fluid; If the predicted Mises stress is greater than or equal to the third stress threshold, a third-level safety warning is issued, and the pipe jacking construction system is controlled to shut down and inject glue into the pipe section behind the pipe jacking head. The first stress threshold, the second stress threshold and the third stress threshold are sequentially increased, and the third stress threshold is a stress extreme value of the pipe section.

3. The method of claim 2, wherein, The first stress threshold is 250Mpa, the second stress threshold is 300Mpa, and the third stress threshold is 345MPa. The control top pipe construction system starts the annular sound wave emission array to emit suppression sound waves to the front soil layer, comprising: The control top pipe construction system injects a thickening agent into the drilling fluid, comprising: The control top pipe construction system injects hydrolyzed polyacrylamide and nano-montmorillonite into the drilling fluid, so that the hydrolyzed polyacrylamide accounts for 0.4%-0.6% of the volume of the mixed drilling fluid, and the nano-montmorillonite accounts for 0.1%-0.2% of the volume of the mixed drilling fluid, until the microwave resonance sensor monitors that the yield stress of the drilling fluid is increased to 150-200Pa; The control top pipe construction system stops and injects quick-setting epoxy resin through the joint embedded hole of the rear pipe section, until the FBG array monitors that the circumferential stress is reduced to 300Mpa. The control top pipe construction system stops and injects quick-setting epoxy resin through the joint embedded hole of the rear pipe section, until the FBG array monitors that the circumferential stress is reduced to 300Mpa. The control top pipe construction system stops and injects quick-setting epoxy resin through the joint embedded hole of the rear pipe section, until the FBG array monitors that the circumferential stress is reduced to 300Mpa.

4. The method of claim 1, wherein, The control top pipe construction system stops and injects quick-setting epoxy resin through the joint embedded hole of the rear pipe section, until the FBG array monitors that the circumferential stress is reduced to 300Mpa. if the yield stress is greater than 80 pa, then the water storage coefficient is determined to be 3 x 10 -5 m -1 ; The control top pipe construction system stops and injects quick-setting epoxy resin through the joint embedded hole of the rear pipe section, until the FBG array monitors that the circumferential stress is reduced to 300Mpa. wherein, K is the storage coefficient of the soil layer around the pipe section, E is the elastic modulus of the soil body, ρ is the drilling fluid density, g is the acceleration of gravity, σy is the yield stress of the drilling fluid.

5. The method of claim 1, wherein, The device comprises: a microwave resonance sensor arranged on the inner wall of the drilling fluid circulation pipeline, a fiber Bragg grating (FBG) array arranged on the inner wall of each rear jacked pipe section, a first pore water pressure gauge array arranged on the outer wall of each rear jacked pipe section, and a second pore water pressure gauge array arranged radially in the soil layer at a predetermined distance in front of the pipe jacking head; and wherein, is the hoop stress of the pipe section, is the radial stress of the pipe section, is the axial stress of the pipe section, is the elastic modulus of the pipe section, is the sum of the earth pressure and the water pressure, is the hoop strain of the pipe section, is the current Mises stress of the pipe section, is the Poisson's ratio, taken as 0.

3.

6. The method of claim 1, wherein, The parameter acquisition module is configured to, during the soil layer drilling process, acquire a water storage coefficient of the soil layer around the pipe section based on the drilling fluid density and the yield stress collected by the microwave resonance sensor, acquire the Misess stress of the pipe section based on the circumferential strain of the pipe section collected by the FBG array, and acquire the seepage pressure gradient based on the measured values of the first pore water pressure gauge array and the second pore water pressure gauge array; wherein, is the seepage pressure gradient, is the measured value of the second array of piezometers, is the measured value of the first array of piezometers, is the radial distance of the second array of piezometers from the pipe jacking head, i.e. the preset distance.

7. A safety prediction device for complex stratum-oriented large-diameter pipe jacking construction, characterized in that, The pipe section stress prediction module is configured to predict the predicted Misess stress of the pipe section in the next prediction time period based on the water storage coefficient, the Misess stress, and the seepage pressure gradient, using a preset seepage stress coupling model, wherein the seepage stress coupling model indicates the relationship between the stress change rate and the seepage pressure gradient and the current stress under a specific water storage coefficient. ​ ​ The early warning and control module is used for issuing different levels of safety early warning based on the predicted Mises stress, and controlling the pipe jacking construction system to perform sound wave suppression, injection of viscosity increasing agent, and emergency shutdown and pipe joint glue injection operation based on the different levels of safety early warning, so as to ensure that the soil drilling is not unstable; The preset seepage stress coupling model is used to predict the predicted Mises stress of the pipe joint in the next prediction time period based on the water storage coefficient, the Mises stress and the seepage pressure gradient, and the specific process is as follows: Before the construction starts, a preliminary seepage stress coupling model is constructed based on the physical mechanism that the seepage pressure gradient drives stress change and the water storage coefficient amplifies the current stress accumulation effect: wherein, is the predicted Misess stress, is the current Misess stress of the pipe section, is the seepage pressure gradient, is the storage coefficient of the soil surrounding the pipe section, is the prediction time period, is the seepage pressure influence coefficient, is the storage coefficient coupling coefficient; The seepage pressure influence coefficient and the water storage coefficient coupling coefficient are calibrated through historical engineering data to obtain the preset seepage stress coupling model; The preset seepage stress coupling model is used to predict the predicted Mises stress of the pipe joint in the prediction time period based on the water storage coefficient, the Mises stress and the seepage pressure gradient, and the specific process is as follows: The water storage coefficient, the Mises stress and the seepage pressure gradient are input into the preset seepage stress coupling model for calculation to obtain the corresponding predicted Mises stress.

8. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to implement the method of any one of claims 1 to 6. 9.A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the method of any one of claims 1 to 6.

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