Slurry shield construction - experimental implementation of coupled splitting risk control system and its application

Abstract

The present invention provides a coupled splitting risk control system for slurry shield construction and experimental implementation, and its application. The experimental system includes a slurry pressure and shield model experimental device and a main unit. The main unit is equipped with a slurry pressure and shield model control subsystem, a slurry pressure and shield tunneling speed early warning subsystem, a stress state and tunneling speed conversion subsystem, and a transmitting and receiving subsystem for connecting to a shield machine at the shield construction site. The slurry pressure and shield model experimental device includes a CT scanning device, a shield model box, a shield machine model, a mud air pressure loading module, and a mud pressure monitoring module. The CT scanning device is equipped with a mobile platform, and the shield model box and shield machine model are placed on the mobile platform. The technical solution of the present invention couples the actual slurry shield project with the slurry shield splitting experimental system in real time, avoiding the possible risk of mud splitting, controlling the project risk, and significantly reducing the project accident rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of shield tunneling, and in particular relates to a slurry shield construction-experimental implementation coupled splitting risk control system and its application. Background Art

[0002] The control of slurry pressure and excavation speed during stratum excavation by slurry shield is crucial. When the shield machine passes through shallow buried deep strata and the overlying soil is below the water level, if the slurry pressure is too high, stratum splitting is likely to occur. The through splitting channel from the excavation surface to the stratum surface will allow water to continuously penetrate through the channel, causing immeasurable accident consequences. The existing disclosed technology mainly focuses on the formation mechanism of shield mud film and the performance analysis experiment of mud film, while the mud stratum splitting experiment has not received much attention. In addition, there is still a gap in the digital visualization of mud penetration and splitting. At present, most research results show that the entire process of dynamic shield tunneling and mud film formation can be realized, but the visualization of mud penetration in the soil has not been achieved. The method of manually excavating to check the mud penetration is not ideal. First, the method of adding colorant to the mud to distinguish the color of the soil is not effective when encountering darker soil. Secondly, and most importantly, the soil is severely disturbed during the excavation process, and the original state of the mud splitting shape or penetration shape is extremely easy to be destroyed. Therefore, the excavation inspection method cannot accurately and truly reflect the experimental results.

[0003] Despite this, some scholars have made some contributions in the direction of slurry shield visualization, but these technologies mainly rely on direct observation through simple methods such as transparent model boxes and transparent soil. However, transparent soil is essentially different from real soil, and there are large differences in soil cohesion, friction angle, porosity and gradation. It is impossible to use a single transparent soil to simulate multiple types of soil such as dry sand, unsaturated soil or silty clay. Therefore, it is impossible to correctly reflect the penetration of mud in the soil layer and the mud splitting mechanism; furthermore, the traditional direct observation method does not combine digitalization and information technology, and only stays at the qualitative analysis of the experiment. It is also very subjective and lacks quantitative measurement of the mud infiltration morphology and scale. Summary of the Invention

[0004] In response to the above technical problems, the present invention discloses a slurry shield construction-experimental implementation coupled splitting risk control system and its application, which can clearly obtain the penetration state of mud in the soil layer and the soil pressure state during the slurry shield process, which is conducive to risk control.

[0005] To this end, the technical solution adopted in the present invention is:

[0006] A slurry shield construction-experimental implementation coupled splitting risk control system includes a slurry pressure and shield model experimental device and a host computer. The host computer is equipped with a slurry pressure and shield model control subsystem, a slurry pressure and shield tunneling speed early warning subsystem, a stress state and tunneling speed conversion subsystem, and a transmitting and receiving subsystem for connecting to the shield machine at the shield construction site.

[0007] The host is equipped with a CT scanning control subsystem, a two-dimensional section Figure 3 Dimensional reconstruction computing subsystem; the host is electrically connected to the display screen and the wireless transmission module;

[0008] The mud water pressure and shield model experimental device includes a CT scanning device, a shield model box, a shield machine model, a mud air pressure loading module and a mud pressure monitoring module. The CT scanning device is provided with a mobile platform, and the shield model box and the shield machine model are placed on the mobile platform.

[0009] The shield model box includes a model box, the model box is provided with a displacement sensor, the model box is provided with an opening for allowing the shield machine model to penetrate, the shield machine model includes a shield machine cutterhead and a mud water tank, the mud water tank is connected to a mud injection pipe and a mud pressure measuring pipe respectively through a pipeline, the other end of the mud injection pipe is connected to the mud output hole of the mud mixer, and the other end of the mud pressure measuring pipe is connected to a mud pressure monitoring module; the mud air pressure loading module is connected to the mud mixer for stirring the mud containing the scanning contrast agent through an air pressure pipe; the shield machine cutterhead is connected to a shield driving mechanism, the shield machine model is connected to a mobile driving mechanism, and the mobile driving mechanism drives the shield machine model to move to perform shield operation;

[0010] The host communicates with the displacement sensor, mobile drive mechanism, shield drive mechanism, mud pressure monitoring module, and mud air pressure loading module. The mud water pressure and shield model control subsystem obtains information from the mud pressure monitoring module and displacement sensor, and controls the mobile drive mechanism, shield drive mechanism, and mud air pressure loading module.

[0011] The mud pressure and shield tunneling speed warning subsystem monitors the mud pressure of the experimental shield in real time (i.e., the data from the mud pressure monitoring module). When the mud pressure is lower than the threshold, the system issues a warning signal, adjusts the pressure of the mud tank, and transmits the warning signal to the shield construction site.

[0012] The stress state and tunneling speed variation subsystem calculates the required slurry pressure for the laboratory shield tunneling system by scaling the preset experimental model with the actual project data collected from the shield construction site. Conversely, the project-scale value is calculated by simultaneously collecting and scaling the real-time experimental data and transmitting feedback to the shield construction site. The experimental model is the experimental model of this slurry pressure and shield model experimental device.

[0013] Furthermore, the mud water pressure and shield tunneling speed early warning subsystem monitors the experimental shield mud water pressure in real time with a time step of 0.1s. When the mud water pressure at a certain time step is monitored to be lower than 10% of the average value of the previous 10 time steps, the system immediately issues an early warning signal and automatically lowers the mud water tank pressure. At the same time, the early warning signal is transmitted to the shield engineering site.

[0014] By adopting this technical solution, in addition to realizing the shield machine model pushing and shield cutter head rotation excavation in the general shield experimental device, it can also realize the simulation of shield mud and water splitting phenomenon.

[0015] During the process of excavating to the high-risk section of slurry splitting at the engineering site, real-time excavation parameters can be transmitted to the host computer via wireless signals. The actual mud pressure and excavation speed are converted into values ​​suitable for the laboratory scale through the stress state and excavation speed conversion subsystem. The parameters are then transmitted to the slurry pressure and shield model control subsystem. The slurry shield excavation test is carried out in the soil with the same or similar water and soil conditions and burial depth as the actual excavation section through the shield model. At the same time, CT scanning is used to obtain a two-dimensional cross-sectional view of the mud splitting morphology in the formation, and then the two-dimensional cross-sectional view is reconstructed in three dimensions to construct a three-dimensional view of the dynamic development process of the mud splitting morphology or the final splitting morphology, thereby realizing qualitative analysis of the mud splitting morphology and quantitative analysis of the splitting area scale. The 3D view obtained allows observation of the slurry penetration morphology and internal earth pressure values. The mud-water pressure and shield tunneling speed warning subsystem receives the results from the scanning system, and gives recommended values ​​through analysis, or manually gives recommended values, which are used as new tunneling parameters. These are fed back to the construction site through the stress state and tunneling speed conversion subsystem, and the shield machine receives signals from the test end to update the tunneling parameters, thus realizing a coupled closed loop.

[0016] The mud-water pressure and shield model experimental device performs input control periodically, and performs high-frequency laboratory internal feedback loop control between adjacent input control time intervals. During this period, the excavation parameters maintain the excavation parameters of the last input control. When there is a large risk of mud splitting or mud splitting occurs during the test, the early warning system immediately sends a warning signal and parameter control signal to the engineering end, and makes timely adjustments to the on-site excavation to avoid engineering accidents caused by mud splitting.

[0017] As a further improvement of the present invention, the mud mixer includes a base and a transparent outer cover, the bottom of the transparent outer cover is connected to the base, an air pressure loading partition is provided in the transparent outer cover, the air pressure loading partition is provided with an air pressure release hole, and the transparent outer cover is connected to the air pressure tube; a stirring blade and a mud output hole are provided on the base, and the stirring blade is connected to the stirring motor.

[0018] As a further improvement of the present invention, the mobile drive mechanism includes a hydraulic cylinder and a hydraulic rod, a model shell loading plate is provided outside the model box, the shell of the shield machine model is supported on the model shell loading plate by a hydraulic rod, and the hydraulic rod is driven by a hydraulic cylinder.

[0019] As a further improvement of the present invention, the box is provided with a 90° bent arm, and the 90° bent arm is connected to the laser point cloud displacement sensor.

[0020] As a further improvement of the present invention, the pipe is a transparent pipe, and further a PP pipe.

[0021] As a further improvement of the present invention, the mud shield splitting visualization experimental system includes AR glasses, which are connected to a host. The host transmits the three-dimensional morphological view of the mud splitting to the AR glasses through a wireless transmission module. The observer can observe the three-dimensional morphology of the mud splitting by any displacement of the model box in situ through the AR glasses, making the research object more intuitive.

[0022] The present invention also discloses a control method for the slurry shield construction-experimental implementation coupled splitting risk control system as described above, comprising the following steps:

[0023] Step S1, experimental preparation:

[0024] The water and soil with the same conditions as the actual project are arranged in the model box, and the soil is laid by layered compaction;

[0025] Use a shield machine cutterhead with a cover-diameter ratio consistent with the actual project;

[0026] Use mud that is consistent with the actual engineering performance and add CT contrast agent, then add it into the mud mixer. The top of the mud liquid surface is compacted with an air pressure loading partition and the air pressure release hole is tightened.

[0027] Start the mud agitator to stir, start the mud air pressure loading module, inject gas into the mud agitator through the air pressure pipe, press the mud in the mud agitator into the mud water tank through the mud injection pipe until it is full, and let the mud flow into the mud pressure monitoring module through the mud pressure measuring pipe until there is a pressure indication, then turn off the air pressure loading;

[0028] The excavation data from the construction site is converted into laboratory-scale model parameters through the stress state and excavation speed conversion subsystem, and then input into the mud water pressure and shield model control subsystem to enter the test phase;

[0029] The excavation data includes mud pressure, excavation speed and cutter head rotation speed, etc.

[0030] Step S2, coupling test stage:

[0031] The shield drive mechanism and the mobile drive mechanism are started, and the host receives data from the actual engineering site through the transmitting and receiving subsystems, and updates the shield model excavation and mud pressure information in real time;

[0032] The CT scanning control subsystem is started. The mobile platform drives the shield model box and the shield machine model to move back and forth for CT scanning. The displacement sensor provides feedback on the displacement and deformation information of the soil surface.

[0033] During the loading splitting process, the CT scanning device and the two-dimensional cross section Figure 3 The 2D reconstruction calculation subsystem works continuously, and in each scanning cycle, the 2D section Figure 3 The 3D reconstruction calculation subsystem calculates a 3D model of mud penetration morphology and displays the mud penetration morphology in the model box in real time;

[0034] The mud permeability morphology and surface displacement information obtained by scanning are input into the mud-water pressure and shield tunneling speed early warning subsystem. Through calculation and analysis, the adjusted tunneling parameter recommended values ​​are obtained, and the adjusted tunneling parameter recommended values ​​are transmitted to the stress state and tunneling speed conversion subsystem to be converted into engineering-scale values. The obtained engineering-scale values ​​are transmitted to the control end of the actual project through the transmitting and receiving subsystem for real-time tunneling parameter control; wherein, the calculation and analysis adopt conventional methods.

[0035] When the mud-water pressure and shield tunneling speed warning subsystem detects abnormal surface displacement or mud splitting, it immediately sends restricted tunneling parameters and warning signals to the actual project control end; at the same time, if abnormal internal soil pressure is observed through human AR, human intervention can be used to recommend values ​​and warning signals.

[0036] In step S3, when the actual shield machine has completely passed the highest-risk tunneling section, the coupling test ends, the transmitting and receiving subsystems are disconnected, and the coupling control ends. The actual shield machine continues to excavate the remaining section of the project according to the design values.

[0037] The present invention also discloses an application of the above-mentioned slurry shield construction-experimental implementation coupled splitting risk control system for three-dimensional reconstruction and in-situ observation of the dynamic development process of slurry splitting morphology during dynamic excavation of a shield machine in pure dry sand strata, comprising the following steps:

[0038] Step S21, experimental preparation:

[0039] The required pure dry sand is compacted and laid in layers in the model box;

[0040] CT contrast agent was added to the mud with a Martens viscosity of 35s and then placed in a mud mixer. The top of the mud surface was compacted with an air pressure loading partition and the air pressure release hole was tightened.

[0041] Start the mud agitator to stir, start the mud air pressure loading module, inject gas into the mud agitator through the air pressure pipe, press the mud in the mud agitator into the mud water tank through the mud injection pipe until it is full, and let the mud flow into the mud pressure monitoring module through the mud pressure measuring pipe until there is a pressure indication, then turn off the air pressure loading;

[0042] Step S22, experimental phase and dynamic scanning:

[0043] The CT scanning control subsystem is started. The mobile platform drives the shield model box and the shield machine model to move back and forth for CT scanning. The displacement sensor provides feedback on the displacement and deformation information of the soil surface.

[0044] Start the shield drive mechanism and mobile drive mechanism, start the shield machine excavation, and at the same time start the mud air pressure loading module to linearly load the mud;

[0045] During the loading splitting process, the CT scanning device and the two-dimensional cross section Figure 3 The 2D reconstruction calculation subsystem works continuously, and in each scanning cycle, the 2D section Figure 3 The 3D reconstruction calculation subsystem calculates a 3D model of the mud penetration morphology and displays the mud penetration morphology in the model box in real time. When the surface of the simulation box bulges and mud gushes out at the moment, indicating that splitting has occurred, the air pressure loading is turned off, the CT scanning and mud stirring are stopped, and the mobile platform returns to its original position.

[0046] Step S23, post-experiment processing and in-situ observation:

[0047] The host sends the three-dimensional model of the mud penetration morphology during splitting to the AR glasses through the wireless transmission module. The operator wears the AR glasses to conduct in-situ observation at any position, thereby achieving intuitive understanding and direct observation of mud splitting in pure dry sand formations.

[0048] After the experiment, the soil and mud in the model box should be cleaned out of the box, the shield machine cutter head opening of the simulation box should be unblocked to prevent mud consolidation and blockage, and the mud in the mud mixer should be cleared.

[0049] The present invention also discloses an application of the above-mentioned slurry shield construction-experimental implementation coupled splitting risk control system, which is used for three-dimensional reconstruction and in-situ observation of the final form of slurry splitting when the shield machine is stationary and not advancing in pure dry sand strata, including the following steps:

[0050] Step S31, experimental preparation:

[0051] The required pure dry sand is compacted and laid in layers in the model box;

[0052] CT contrast agent was added to the mud with a Martens viscosity of 35s and then placed in a mud mixer. The top of the mud surface was compacted with an air pressure loading partition and the air pressure release hole was tightened.

[0053] Start the mud agitator to stir, start the mud air pressure loading module, inject gas into the mud agitator through the air pressure pipe, press the mud in the mud agitator into the mud water tank through the mud injection pipe until it is full, and let the mud flow into the mud pressure monitoring module through the mud pressure measuring pipe until there is a pressure indication, then turn off the air pressure loading;

[0054] Step S32, experimental stage:

[0055] The displacement sensor feeds back the displacement and deformation information of the soil surface, and the mud air pressure loading module is turned on to linearly load the mud. When the surface bulges and mud sprays out at the moment, it indicates that splitting has occurred. The air pressure loading is then turned off, and the experiment is complete.

[0056] Step S33: 3D reconstruction and in-situ observation of the mud splitting morphology:

[0057] Start the CT scanning control subsystem, and the mobile platform drives the shield model box and the shield machine model to move forward and backward for CT scanning. Figure 3 The 3D reconstruction calculation subsystem reconstructs a complete 3D model of the mud formation splitting, turns off the CT scanning and mud stirring, and returns the mobile platform to its original position;

[0058] The host sends the three-dimensional model of the mud penetration morphology during splitting to the AR glasses through the wireless transmission module. The operator wears the AR glasses to conduct in-situ observation at any position, thereby achieving intuitive understanding and direct observation of mud splitting in pure dry sand formations.

[0059] After the experiment, the soil and mud in the model box should be cleaned out of the box, the shield machine cutter head opening of the simulation box should be unblocked to prevent mud consolidation and blockage, and the mud in the mud mixer should be cleared.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] First, by adopting the technical solution of the present invention, with the help of a scaled indoor slurry shield splitting test system, the actual slurry balance shield project is coupled with the slurry shield splitting test system in real time, and the mud splitting risk can be calculated. Through the test, the tunneling parameters such as the slurry pressure of the shield machine at the project site are adjusted in real time to avoid the possible mud splitting risk, control the project risk, and greatly reduce the project accident rate.

[0062] Second, experiments on the slurry splitting phenomenon during shield tunneling were conducted. Based on this, digital and intelligent technologies were combined to use CT scanning to achieve two-dimensional cross-sectional scanning and three-dimensional morphological reconstruction of the original slurry splitting form without soil disturbance, thus enabling visualization and quantitative measurement of slurry shield splitting. Furthermore, augmented reality (AR) technology could be used to provide relevant researchers with real-time in-situ dynamic observation of the slurry penetration form and internal soil pressure conditions, allowing researchers to provide real-time feedback on the recommended values ​​of on-site shield tunneling parameters.

[0063] Third, the technical solution of the present invention fills the gap in the lack of effective experimental equipment in mud splitting experiments, and provides practical support for in-depth research on mud pressure control of slurry balance shield machines passing through shallow buried strata and the formation mechanism of shield mud splitting. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is a structural diagram and workflow of a slurry shield splitting experimental system according to an embodiment of the present invention.

[0065] Figure 2 It is a front view of the mud water pressure and shield model experimental device according to an embodiment of the present invention.

[0066] Figure 3 It is a rear view of the mud water pressure and shield model experimental device according to an embodiment of the present invention.

[0067] Figure 4 This is a connection diagram of the shield model box and the host computer, etc. according to an embodiment of the present invention.

[0068] Figure 5 This is an overall assembly diagram of the shield model box according to an embodiment of the present invention.

[0069] Figure 6 This is an overall assembly diagram of the shield model box from another angle according to an embodiment of the present invention.

[0070] Figure 7 It is an overall perspective view of the shield model box assembly according to an embodiment of the present invention.

[0071] Figure 8 Schematic diagram of the cutter head hole arrangement according to an embodiment of the present invention.

[0072] Figure 9 1 is an exploded view of a mud mixer according to an embodiment of the present invention.

[0073] Reference numerals include:

[0074] 1-CT scanner body, 2-operating platform and steps, 3-mobile platform track, 4-mobile platform, 5-model box, 6-shield machine model shell, 7-model shell loading plate, 8-point cloud laser scanner, 9-shield drive motor, 10-hydraulic cylinder, 11-hydraulic rod, 12-AR glasses, 13-mud mixer, 14-mud injection pipe, 15-mud pressure measuring tube, 16-air pressure tube, 17-line, 18-integrated platform, 19-display, 20-host, 21-transparent outer cover, 22-air pressure loading partition, 23-air pressure release hole, 24-mixing blade, 25-mud output hole, 26-base, 27-extension plate, 28-cutter head spindle, 29-mud and water tank, 30-cutter head. DETAILED DESCRIPTION

[0075] The preferred embodiments of the present invention are described in further detail below.

[0076] like Figure 1 As shown, a slurry shield construction-experimental implementation coupled splitting risk control system includes a slurry pressure and shield model experimental device and a host 20, wherein the host 20 is equipped with a main control system, a slurry pressure and shield model control subsystem, a slurry pressure and shield tunneling speed early warning subsystem (hereinafter referred to as the early warning system), a stress state and tunneling speed conversion subsystem (hereinafter referred to as the conversion system), a transmitting and receiving subsystem for connecting to the shield machine at the shield construction site, a CT scanning control subsystem, a two-dimensional cross-section Figure 3 The dimensional reconstruction calculation subsystem and AR subsystem are connected; the host 20 is electrically connected to the display screen 19 and the wireless transmission module. The mud pressure and shield tunneling speed warning system monitors the experimental shield mud pressure in real time with a time step of 0.1s. When the mud pressure at a certain time step is lower than 10% of the average value of the previous 10 time steps, the system immediately issues a warning signal and automatically lowers the mud tank pressure. The warning signal is also transmitted to the shield engineering site. The stress state and tunneling speed change subsystem calculates the required mud pressure for the laboratory shield by scaling and calculating the real-time data collected from the project based on the ratio of the preset experimental model to the actual project. Conversely, the engineering scale value is calculated by scaling and calculating the real-time data collected from the experiment and transmitted back to the engineering site.

[0077] like Figures 2 to 5 As shown, the mud water pressure and shield model experimental device includes a CT scanning device, a shield model box, a shield machine model, a mud air pressure loading module, a mud pressure monitoring module and AR glasses 12. The host 20 is connected to the CT scanning device through a line 17.

[0078] Specifically, the CT scanning device includes a CT scanner body 1, an operating platform and steps 2, a mobile platform 4 track 3, and a mobile platform 4. The shield model box and the shield machine model are placed on the mobile platform 4; the mobile platform 4 is controlled by the CT scanning control subsystem. The shield model box includes a model box 5 with transparent organic glass on three sides. The model box 5 is connected to the point cloud laser scanner 8 with a 90° bent arm. The model box 5 is provided with an opening for allowing the shield machine model to pass through. The shield machine model includes a cutterhead 30 with an opening, a cutterhead spindle 28 and a mud and water tank 29. The mud and water tank 29 is connected to a mud injection pipe 14 and a mud pressure measuring pipe 15 through two transparent PP pipes respectively. The other end of the mud injection pipe 14 is connected to the mud output hole 25 of the mud mixer 13, and the other end of the mud pressure measuring pipe 15 is connected to the mud pressure inlet hole and connected to the mud pressure monitoring module; the mud air pressure loading module is connected to the mud mixer 13 for stirring the mud containing the scanning contrast agent through the air pressure pipe 16; the shield machine cutterhead 30 is provided with an opening and connected to the cutterhead spindle 28, and the cutterhead spindle 28 is connected to the shield drive motor 9; the bottom of the shield drive motor 9 is fixed on the extension plate 27 of the shield machine model shell 6. The shield machine model is connected to a mobile drive mechanism, specifically, a hydraulic cylinder 10 and a hydraulic rod 11. A model housing loading plate 7 is provided outside the model box 5. The shield machine model housing is supported on the model housing loading plate 7 by two hydraulic rods 11, which are driven by the hydraulic cylinder 10. The mud pressure monitoring module and the mud air pressure loading module are located within the integrated platform 18.

[0079] The mud mixer 13 includes a base 26 and a transparent outer cover 21. The bottom of the transparent outer cover 21 is connected to the base 26. An air pressure loading partition 22 is provided in the transparent outer cover 21. The air pressure loading partition 22 is provided with an air pressure release hole 23. The top of the transparent outer cover 21 is connected to the air pressure tube 16 and the air pressure loading air inlet. The base 26 is provided with a stirring blade 24 and a mud output hole 25. The stirring blade 24 is connected to the stirring motor. The stirring motor is arranged in the base 26. The mud output hole 25 is connected to the mud injection pipe 14. The air pressure loading partition 22 is used to separate the stirred mud and the loaded air pressure. Barium sulfate is added to the mud as a scanning contrast agent, and the whole is covered with a transparent cylindrical glass cover, that is, the transparent outer cover 21.

[0080] The host 20 communicates with the displacement sensor, mobile drive mechanism, shield drive mechanism, mud pressure monitoring module, mud air pressure loading module, CT scanning device, and AR glasses 12. The mud water pressure and shield model control subsystem obtains information from the mud pressure monitoring module and displacement sensor, and controls the mobile drive mechanism, shield drive mechanism, and mud air pressure loading module.

[0081] In this system, the shield model box is placed as a whole on the mobile platform 4 of the CT scanning device. The movement of the mobile platform 4 is controlled by the CT scanning control subsystem. After the CT scan is started, the shield model box as a whole passes through the semicircular area of ​​the CT scanning device for two-dimensional cross-sectional scanning. The CT scanning device is provided with steps for personnel movement.

[0082] like Figure 1 As shown in the figure, the system realizes the following functions: when the engineering site is excavated to the high-risk section of mud-water splitting, the real-time excavation parameters are transmitted to the laboratory model test control system through wireless signals, the actual mud pressure and excavation speed are converted into values ​​suitable for the laboratory scale through the conversion system, and the parameters are then transmitted to the model control system. The slurry shield excavation test is carried out in the soil with water and soil conditions and burial depth similar to the actual excavation section through the shield model. At the same time, the three-dimensional (3D) morphology of mud penetration in the soil layer is scanned by CT, and the mud penetration morphology and internal earth pressure value are observed in situ through artificial AR. The early warning system receives the results from the scanning system and evaluates the mud splitting risk. Risk, at the same time, a recommended value is given through the system or manually. The signal is fed back to the engineering site as a new excavation parameter through the change system processing. The shield machine receives the signal from the test end to update the excavation parameter to realize the coupled closed loop; the model control system performs input control every 30 seconds, and performs high-frequency laboratory internal feedback loop control between adjacent input control time intervals. During this period, the excavation parameters maintain the excavation parameters of the last input control. When there is a large risk of mud splitting or mud splitting occurs in the test, the early warning system immediately sends a warning signal and parameter control signal to the engineering end, and makes timely adjustments to the on-site excavation to avoid engineering accidents such as mud splitting.

[0083] In the test system, in addition to realizing the shield machine model jacking and shield cutter head rotation excavation in general shield experimental devices, the shield mud splitting phenomenon can also be realized. During the mud splitting experiment and after the experiment is completed, the central control system can automatically perform a mobile CT scan on the mobile platform below the model box to obtain a two-dimensional cross-sectional image of the mud splitting morphology in the stratum. Then, the two-dimensional cross-sectional image is reconstructed in three dimensions to construct a three-dimensional view of the dynamic development process of the mud splitting morphology or the final splitting morphology, thereby realizing qualitative analysis of the mud splitting morphology and quantitative analysis of the splitting area scale. In addition, the three-dimensional morphological view of the mud splitting is transmitted to the AR glasses through wireless transmission. Researchers can use the AR glasses to directly realize the in-situ arbitrary displacement of the model box and dynamically observe the three-dimensional morphology of the mud splitting, making the research object more intuitive.

[0084] The above-mentioned slurry shield construction-experimental implementation coupled splitting risk control system can be used for coupled risk control with the shield tunneling process at the engineering site, and the test system can also be used independently for slurry splitting mechanism research. The implementation plan is:

[0085] (1) Real-time coupled risk control of construction excavation and test excavation

[0086] 1. Test preparation:

[0087] A geological survey is conducted on the excavation sections in the project where the shield machine is excavating upward with a small burial depth, passing under the riverbed and having a shear groove. After obtaining the hydrological condition report of the actual survey, approximate water and soil conditions are arranged in the model box to keep the shield's cover-diameter ratio consistent with the actual one. The soil is laid by layered compaction, with one round of compaction every 0.5D.

[0088] The viscosity was measured using a Marsh funnel and the same mud as that used in actual engineering was used for the experiment. 5% barium sulfate was added to the mud as a CT contrast agent. The mud was placed in a mud mixer, and the top of the liquid surface was compacted with an air pressure loading partition and the air pressure release hole was tightened.

[0089] The host starts the connection of the CT scanning control subsystem, the model mud water pressure and the shield model control subsystem. After the mud mixer starts to stir the mud for 5 minutes, a small amount of air pressure is adjusted to inject into the mud mixer through the air pressure tube. The mud in the mixer is pressed into the mud water bin of the shield machine through the mud injection pipe until it is full. The mud flows into the mud pressure monitoring module through the mud pressure measuring tube. The pressure measuring system has a digital display, that is, the air pressure loading is turned off, and the transmitting and receiving system starts to receive the excavation data from the project site, including mud pressure, excavation speed and cutterhead speed, and converts the actual mud pressure and other excavation parameters into laboratory-scale model parameters through the conversion system, and transmits them to the control system to enter the test phase.

[0090] 2. Coupling test stage:

[0091] During the test, the excavation progress of the model needs to be slightly ahead of the actual project, so as to detect the splitting risk in advance and give timely warning.

[0092] After tunneling information is input into the control system, the shield drive motor and hydraulic cylinder are activated. The shield model's tunneling progress and mud pressure are updated and controlled in real time based on the received information. The CT scanning control subsystem initiates scanning, and the mobile platform automatically moves the shield model box and the shield machine model back and forth along the mobile platform track at a constant speed for CT scanning. A point cloud laser scanner is activated to detect soil surface displacement and deformation. During the loading and splitting process, the CT scanning and 3D reconstruction calculation system operates continuously, with a scan cycle of 30 seconds. A 3D model of the mud penetration pattern is calculated and displayed in real time within the model box. The scanned mud penetration pattern and surface displacement information are input into the early warning system. After computational analysis, the recommended values ​​for adjusted tunneling parameters are transmitted to the transformation system, converted to engineering-scale values, and output. These values ​​are then transmitted to the engineering end through the transmitter-receiver system for real-time tunneling parameter control. If the early warning system detects abnormal surface displacement or mud splitting, it immediately issues restricted tunneling parameters and a warning signal to the engineering end. Furthermore, if abnormal internal soil pressure is observed through AR, the recommended values ​​and warning signal can be manually adjusted.

[0093] 3. End of the trial:

[0094] When the shield machine completely passes through the tunneling section with the highest risk in the actual project, the coupling test can be ended, the engineering end and the test section can disconnect the transmission and reception to end the coupling control, and the engineering end shield machine continues to excavate the remaining engineering part according to the design value.

[0095] (2) 3D reconstruction of the final shape of slurry splitting when the shield machine is stationary and not advancing in pure dry sand strata

[0096] 1. Experimental Preparation:

[0097] First, the required pure dry sand is compacted and laid in layers in the model box, with one round of compaction every 0.5D. A total of 4 layers of soil are laid, and the final buried depth of the shield machine is 0.5D.

[0098] The experiment was conducted using mud with a Martens viscosity of 35s. 5% barium sulfate was added to the mud as a CT contrast agent. The mud was placed in a mud mixer, and the top of the liquid surface was compacted with an air pressure loading partition and the air pressure release hole was tightened.

[0099] The host starts the connection of the CT scanning control subsystem, the model mud water pressure and the shield model control subsystem. After the mud mixer starts to stir the mud for 5 minutes, a small amount of air pressure is adjusted to be injected into the mud mixer through the air pressure pipe. The mud in the mixer is pressed into the mud and water bin of the shield machine through the mud injection pipe until it is filled. The mud flows into the mud pressure monitoring module through the mud pressure measuring tube. The pressure measuring system has a reading display, that is, the air pressure loading is turned off and the experimental stage begins.

[0100] 2. Experimental phase and dynamic scanning:

[0101] Start the CT scanning control subsystem to start scanning. The mobile platform drives the upper shield model box and shield machine model to automatically move forward and backward at a constant speed along the mobile platform track for CT scanning. Start the point cloud laser scanner to detect the displacement and deformation of the soil surface. Start the shield drive motor and hydraulic cylinder to start the shield machine excavation. The shield machine cutter head speed is 3rpm, the thrust speed is 0.1mm / s, and the air pressure is turned on to load the mud. Linear loading is used and the loading speed is 0.5kPa / s. During the loading and splitting process, CT scanning and two-dimensional cross-section Figure 3 The 3D reconstruction calculation subsystem works continuously, with a scanning cycle of 30 seconds. It calculates and completes a 3D model of mud penetration morphology, and displays the dynamic development of mud splitting in the model box in real time. When mud ejects at the moment of surface bulge, it indicates that splitting has occurred, and the air pressure loading is turned off.

[0102] 3. Post-experimental processing and in-situ observation:

[0103] Once the splitting phenomenon occurs, the pneumatic loading is immediately terminated, the CT scanning control subsystem and mud mixing are shut down, and the mobile platform is returned to its original position. A 3D model of the splitting morphology is wirelessly transmitted to the AR glasses. Based on the positioning of the characteristic points of the model box, a 3D AR image of the splitting morphology is displayed at the actual location of the model box. The AR glasses can be worn to observe the splitting morphology in situ at any position through the operating platform and steps, thus achieving an intuitive understanding and direct observation of the mud splitting in the pure dry sand formation. After the experiment, the soil and mud in the model box should be cleared out of the box, the shield machine cutterhead opening should be promptly unblocked to prevent mud consolidation and blockage, and the mud in the mud mixing system should also be promptly removed.

[0104] (3) 3D reconstruction of the final shape of slurry splitting when the shield machine is stationary and not advancing in pure dry sand strata

[0105] 1. Experimental Preparation:

[0106] This step is consistent with Implementation Plan (II).

[0107] 2. Experimental stage:

[0108] The point cloud laser scanner was started through the central control system to detect the displacement and deformation of the soil surface. The air pressure loading of the mud was turned on, and linear loading was adopted with a loading speed of 0.5 kPa / s. When the mud was ejected at the moment when the surface bulged, it indicated that splitting occurred. The air pressure loading was then turned off and the experiment was completed.

[0109] 3. 3D reconstruction and in-situ observation of mud splitting morphology:

[0110] Start the CT scanning control subsystem to start scanning. The mobile platform drives the upper shield model box and shield machine model to move forward and backward automatically at a constant speed along the mobile platform track to perform CT scanning, and through the two-dimensional section Figure 3 The 3D reconstruction calculation subsystem performs 3D reconstruction to reconstruct a complete 3D model of mud formation splitting. The CT scanning and mud stirring are turned off, the mobile platform returns to its original position, and the 3D model of the splitting shape is sent to the AR glasses via wireless transmission. Based on the positioning of the feature points of the model box, the 3D AR image of the splitting shape can be presented at the actual position of the model box. The user can wear AR glasses and conduct in-situ observation at any position through the operating platform and steps, thereby realizing intuitive understanding and direct observation of mud splitting in pure dry sand formations.

[0111] 4. Post-experimental processing:

[0112] After the experiment, the soil and mud in the model box should be cleaned out of the box, the shield machine cutter head opening should be cleared in time to prevent mud solidification and blockage, and the mud in the mud mixing system should also be cleared in time.

[0113] The AR glasses involved in the aforementioned technical solution include an AR in-situ real-time observation algorithm in the host. This AR in-situ real-time observation algorithm involves the definition of the test system, data filtering, noise analysis, and mechanical parameter calculation, and uses existing technologies. Specifically, it includes the following:

[0114] The initial information state is set to s t , process noise and sensor observation noise are set to η k and λ k , the noise changes of the two are represented by Q and R, that is,

[0115]

[0116] l t =Cs t +λ k (0.1) t is time, ε t is the strain information, D t is the displacement information.

[0117] The solution uses the last optimization result to predict the current value, and uses the observed value to correct the current value to obtain the optimized value, and uses the information at time t-1 to predict the information at time t.

[0118]

[0119] P t =FP t-1 F T +Q (0.2)

[0120] Each iteration predicts and corrects the value at time t based on the value at time t-1, and the value at time t-1 needs to be updated after each correction.

[0121] K t =P t-1 H T (HP t-1 H T +R) -1 (0.3) CT scanning involves grayscale mapping, denoising, mud morphology grayscale processing of the original image, 3D reconstruction of 2D sections, refinement and post-processing of the reconstructed surface, etc.

[0122] The grayscale map is calculated using the following method:

[0123]

[0124] Where: a and b are the images before and after mapping respectively; p0 and p 99.9 The 0th and 99.9th percentiles, respectively, p0 = -1024.

[0125] In order to reduce the amount of calculation, the non-global pixels are weighted averaged, and the relationship between the weight degree and the neighborhood block is:

[0126]

[0127] Where: u(x) is the grayscale value of point x after filtering; R(x) is the square area with a side length of 2r+1 around x, that is, the search area; λ(y) is the grayscale value of image y; u(x) is the normalization coefficient.

[0128] In plane detection, the plane equation is given in Hesse normal form:

[0129]

[0130] Where: r is the coordinate vector, is the unit normal vector of the plane.

[0131] Geometric center coordinates:

[0132]

[0133] Singular Value Decomposition:

[0134]

[0135] Euclidean change matrix:

[0136]

[0137] From the above formula, we can get the plane equation in Hesse normal form and obtain the transformation matrix.

[0138] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A slurry shield construction-experimental implementation coupled splitting risk control splitting experimental system, characterized by: The system includes a mud-water pressure and shield model experimental device and a host computer, wherein the host computer is equipped with a mud-water pressure and shield model control subsystem, a mud-water pressure and shield tunneling speed early warning subsystem, a stress state and tunneling speed conversion subsystem, and a transmitting and receiving subsystem for connecting to a shield machine at a shield construction site. The host is equipped with a CT scanning control subsystem and a two-dimensional cross-sectional image three-dimensional reconstruction calculation subsystem; the host is electrically connected to the display screen and the wireless transmission module; The mud water pressure and shield model experimental device includes a CT scanning device, a shield model box, a shield machine model, a mud air pressure loading module and a mud pressure monitoring module. The CT scanning device is provided with a mobile platform, and the shield model box and the shield machine model are placed on the mobile platform. The shield model box includes a model box, the model box is provided with a displacement sensor, the model box is provided with an opening for allowing the shield machine model to penetrate, the shield machine model includes a shield machine cutterhead and a mud water tank, the mud water tank is connected to a mud injection pipe and a mud pressure measuring pipe respectively through a pipeline, the other end of the mud injection pipe is connected to the mud output hole of the mud mixer, and the other end of the mud pressure measuring pipe is connected to a mud pressure monitoring module; the mud air pressure loading module is connected to the mud mixer for stirring the mud containing the scanning contrast agent through an air pressure pipe; the shield machine cutterhead is connected to a shield driving mechanism, the shield machine model is connected to a mobile driving mechanism, and the mobile driving mechanism drives the shield machine model to move to perform shield operation; The host communicates with the displacement sensor, the mobile drive mechanism, the shield drive mechanism, the mud pressure monitoring module, and the mud air pressure loading module. The mud water pressure and shield model control subsystem obtains information from the mud pressure monitoring module and the displacement sensor, and controls the mobile drive mechanism, the shield drive mechanism, and the mud air pressure loading module. The mud pressure and shield tunneling speed warning subsystem monitors the mud pressure of the experimental shield in real time. When the mud pressure is lower than the threshold, the system issues a warning signal, adjusts the pressure of the mud tank, and transmits the warning signal to the shield construction site. The stress state and tunneling speed change subsystem obtains the mud pressure required for the laboratory shield by scaling calculation through the ratio of the preset experimental model to the actual project and by collecting real-time data from the shield construction project site. Conversely, the engineering scale value is obtained by scaling calculation through the collection of real-time experimental data at the same time, and is transmitted and fed back to the shield construction project site.

2. The slurry shield construction-experimental implementation coupled splitting risk control system according to claim 1, characterized in that: The mud mixer includes a base and a transparent outer cover, the bottom of the transparent outer cover is connected to the base, an air pressure loading partition is provided in the transparent outer cover, the air pressure loading partition is provided with an air pressure release hole, and the transparent outer cover is connected to the air pressure tube; a stirring blade and a mud output hole are provided on the base, and the stirring blade is connected to the stirring motor.

3. The slurry shield construction-experimental implementation coupled splitting risk control system according to claim 1, characterized in that: The mobile driving mechanism includes a hydraulic cylinder and a hydraulic rod. A model shell loading plate is provided outside the model box. The shell of the shield machine model is supported on the model shell loading plate through a hydraulic rod. The hydraulic rod is driven by the hydraulic cylinder.

4. The slurry shield construction-experimental implementation coupled splitting risk control system according to claim 1, characterized in that: The model box is provided with a 90° bent arm, and the 90° bent arm is connected to the laser point cloud displacement sensor.

5. The slurry shield construction-experimental implementation coupled splitting risk control system according to claim 1, characterized in that: The pipeline is a transparent tube.

6. The slurry shield construction-experimental implementation coupled splitting risk control system according to claim 1, characterized in that: It includes AR glasses, which are connected to a host. The host transmits the three-dimensional morphological view of mud splitting to the AR glasses through a wireless transmission module. The observer observes the three-dimensional morphology of mud splitting by dynamically observing the arbitrary displacement of the model box in situ through the AR glasses.

7. The control method for the slurry shield construction-experimental implementation coupled splitting risk control system according to any one of claims 1 to 6, characterized in that: The steps include: Step S1, experimental preparation: The water and soil with the same conditions as the actual project are arranged in the model box, and the soil is laid by layered compaction; Use a shield machine cutterhead with a cover-diameter ratio consistent with the actual project; Use mud that is consistent with the actual engineering performance and add CT contrast agent, then add it into the mud mixer. The top of the mud liquid surface is compacted with an air pressure loading partition and the air pressure release hole is tightened. Start the mud agitator to stir, start the mud air pressure loading module, inject gas into the mud agitator through the air pressure pipe, press the mud in the mud agitator into the mud water tank through the mud injection pipe until it is full, and let the mud flow into the mud pressure monitoring module through the mud pressure measuring pipe until there is a pressure indication, then turn off the air pressure loading; The excavation data from the construction site is converted into laboratory-scale model parameters through the stress state and excavation speed conversion subsystem, and then input into the mud water pressure and shield model control subsystem to enter the test phase; The excavation data includes mud pressure, excavation speed and cutterhead speed; Step S2, coupling test stage: The shield drive mechanism and the mobile drive mechanism are started, and the host receives data from the actual engineering site through the transmitting and receiving subsystems, and updates the shield model excavation and mud pressure information in real time; The CT scanning control subsystem is started. The mobile platform drives the shield model box and the shield machine model to move back and forth for CT scanning. The displacement sensor provides feedback on the displacement and deformation information of the soil surface. During the loading and splitting process, the CT scanning device and the two-dimensional cross-sectional image three-dimensional reconstruction calculation subsystem work continuously. In each scanning cycle, the two-dimensional cross-sectional image three-dimensional reconstruction calculation subsystem calculates a three-dimensional model of the mud penetration morphology and displays the mud penetration morphology in the model box in real time. The scanned mud permeability morphology and surface displacement information is input into the mud-water pressure and shield tunneling speed early warning subsystem. Through calculation and analysis, the recommended values ​​for adjusted tunneling parameters are obtained. These recommended values ​​are then transmitted to the stress state and tunneling speed conversion subsystem and converted into engineering-scale values. The obtained engineering-scale values ​​are then transmitted to the control end of the actual project through the transmitting and receiving subsystem for real-time tunneling parameter control. When the mud-water pressure and shield tunneling speed warning subsystem detects abnormal surface displacement or mud splitting, it immediately sends restricted tunneling parameters and warning signals to the actual project control end; at the same time, if abnormal internal soil pressure is observed through artificial AR, human intervention recommended values ​​and warning signals will be issued.

8. Step S3: When the shield machine has completely passed the tunneling section with the highest risk in the actual project, the coupling test is terminated, the transmitting and receiving subsystems are disconnected, and the coupling control is ended.

9. The application of the coupled splitting risk control system for slurry shield construction-experimental implementation as claimed in claim 6, characterized in that: The three-dimensional reconstruction and in-situ observation of the dynamic development process of slurry splitting morphology during shield machine dynamic excavation in pure dry sand strata include the following steps: Step S21, experimental preparation: The required pure dry sand is compacted and laid in layers in the model box; CT contrast agent was added to the mud with a Martens viscosity of 35s and then placed in a mud mixer. The top of the mud surface was compacted with an air pressure loading partition and the air pressure release hole was tightened. Start the mud agitator to stir, start the mud air pressure loading module, inject gas into the mud agitator through the air pressure pipe, press the mud in the mud agitator into the mud water tank through the mud injection pipe until it is full, and let the mud flow into the mud pressure monitoring module through the mud pressure measuring pipe until there is a pressure indication, then turn off the air pressure loading; Step S22, experimental phase and dynamic scanning: The CT scanning control subsystem is started. The mobile platform drives the shield model box and the shield machine model to move back and forth for CT scanning. The displacement sensor provides feedback on the displacement and deformation information of the soil surface. Start the shield drive mechanism and mobile drive mechanism, start the shield machine excavation, and at the same time start the mud air pressure loading module to linearly load the mud; During the loading and splitting process, the CT scanning device and the two-dimensional cross-sectional image three-dimensional reconstruction calculation subsystem work continuously. In each scanning cycle, the two-dimensional cross-sectional image three-dimensional reconstruction calculation subsystem calculates a three-dimensional model of the mud penetration morphology and displays the mud penetration morphology in the model box in real time. When the surface of the simulation box bulges and mud sprays out at the moment, indicating that splitting has occurred, the air pressure loading is turned off, and the CT scanning and mud stirring are stopped, and the mobile platform returns to its original position; Step S23, post-experiment processing and in-situ observation: The host sends the three-dimensional model of the mud penetration morphology during splitting to the AR glasses through the wireless transmission module. The operator wears the AR glasses to conduct in-situ observation at any position, thereby achieving intuitive understanding and direct observation of mud splitting in pure dry sand formations.

10. The application of the coupled splitting risk control system for slurry shield construction-experimental implementation as claimed in claim 6, characterized in that: The method is used for 3D reconstruction and in-situ observation of the final shape of slurry splitting when the shield machine is stationary and not advancing in pure dry sand strata, including the following steps: Step S31, experimental preparation: The required pure dry sand is compacted and laid in layers in the model box; CT contrast agent was added to the mud with a Martens viscosity of 35s and then placed in a mud mixer. The top of the mud surface was compacted with an air pressure loading partition and the air pressure release hole was tightened. Start the mud agitator to stir, start the mud air pressure loading module, inject gas into the mud agitator through the air pressure pipe, press the mud in the mud agitator into the mud water tank through the mud injection pipe until it is full, and let the mud flow into the mud pressure monitoring module through the mud pressure measuring pipe until there is a pressure indication, then turn off the air pressure loading; Step S32, experimental stage: The displacement sensor feeds back the displacement and deformation information of the soil surface, and the mud air pressure loading module is turned on to linearly load the mud. When the surface bulges and mud sprays out at the moment, it indicates that splitting has occurred. The air pressure loading is then turned off, and the experiment is completed. Step S33: 3D reconstruction and in-situ observation of the mud splitting morphology: The CT scanning control subsystem is activated, and the mobile platform drives the shield model box and shield machine model to move back and forth for CT scanning. The complete 3D model of the mud formation splitting is reconstructed through the 2D cross-section image 3D reconstruction calculation subsystem. The CT scanning and mud mixing are turned off, and the mobile platform returns to its original position. The host sends the three-dimensional model of the mud penetration morphology during splitting to the AR glasses through the wireless transmission module. The operator wears the AR glasses to conduct in-situ observation at any position, thereby achieving intuitive understanding and direct observation of mud splitting in pure dry sand formations.

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