Shield tunneling machine composite stratum tunneling prediction method based on discrete element simulation and storage medium

Abstract

The invention provides a shield tunneling machine composite stratum tunneling prediction method based on discrete element simulation and a storage medium. The shield tunneling machine composite stratum tunneling prediction method comprises the steps of collecting stratum parameters of a shield construction section; establishing a three-dimensional model of the cutterhead; constructing a single-layer geological soil model in discrete element modeling software to form a tunneling simulation model; setting the thrust and the rotating speed of the cutterhead to carry out single-layer geological tunneling simulation, and obtaining tunneling speeds under different working conditions; establishing a mathematical model of the single-layer geological tunneling speed; according to the method, simulation is conducted on the single-layer geological tunneling process of the shield tunneling machine through EDEM software, a large amount of single-layer geological simulation data are obtained, the tunneling progress prediction from the single-layer geology to the composite stratum is achieved through weighted calculation, the prediction precision problem caused by insufficient data in the early stage of construction is solved, and the construction efficiency is improved. And the influence of the stratum change in the composite stratum on the tunneling efficiency can be effectively dealt with, and a reliable technical means is provided for accurate prediction of the tunneling progress of the shield tunneling machine.

Description

Technical Field

[0001] This invention relates to the field of tunnel boring machine (TBM) excavation prediction, and in particular to a method and storage medium for predicting TBM excavation in complex strata based on discrete element method (DEM) simulation. Background Technology

[0002] With the rapid development of infrastructure construction in my country, the shield tunneling method, as a highly efficient tunnel construction technology, has been widely used in tunnel engineering for water conservancy and hydropower, underground engineering, and urban rail transit. Compared with the traditional drill and blast method, the shield tunneling method has significant advantages such as faster excavation speed, construction safety, and environmental friendliness. However, the tunneling efficiency of the shield machine (including penetration depth, tunneling speed, and tunneling progress) is an important reference for equipment operation and project construction planning. Therefore, accurately predicting the tunneling progress of the shield machine is crucial for the smooth progress of the construction project.

[0003] Currently, domestic and international research on the prediction of tunnel boring machine (TBM) speed and progress mainly focuses on empirical models and intelligent models. Empirical models are typically built based on specific geological conditions, and their predictions are often unreliable when applied to new geological environments or complex strata. Furthermore, while intelligent models improve prediction accuracy to some extent, their accuracy significantly decreases in the early stages of construction due to insufficient data. This is primarily because intelligent models require a large amount of tunneling cycle data for training, which is often difficult to obtain in the initial stages of construction.

[0004] In practical engineering, tunnel boring machines (TBMs) often need to excavate in complex geological formations, meaning that multiple strata with different properties exist within the same construction section. The mechanical properties of complex strata are complex, with significant differences in parameters such as compressive strength and shear strength between different strata. This poses a greater challenge to predicting the tunneling progress. Traditional prediction methods often fail to accurately reflect the impact of strata changes on tunneling efficiency when dealing with complex strata, leading to significant deviations between predicted results and actual construction progress.

[0005] In recent years, the Discrete Element Method (DEM), as an advanced numerical simulation method, has been widely used in geotechnical mechanics and tunnel engineering. Using DEM simulation software (such as EDEM), the tunneling process of a tunnel boring machine (TBM) can be simulated with high precision, obtaining various parameters during the tunneling process (such as tunneling speed and cutterhead torque). The advantage of DEM simulation technology lies in its ability to simulate the complex interactions between particles, thus more accurately reflecting the mechanical behavior of the strata. Furthermore, DEM simulation can be performed in the early stages of construction, without being limited by the amount of actual construction data, providing a new solution for predicting the progress of TBM tunneling.

[0006] Therefore, the applicant developed a prediction method for tunnel boring machines in composite strata based on discrete element simulation, which solves the problem of reduced prediction accuracy in existing prediction technologies. Summary of the Invention

[0007] This invention proposes a prediction method for tunnel boring machine (TBM) excavation in complex strata based on discrete element method (DEM) simulation, solving the problems mentioned in the background art. The technical solution of this invention is implemented as follows: A method for predicting the tunneling progress of tunnel boring machines in complex strata based on discrete element simulation includes: Step S1: Collect stratum parameters for each section of the tunnel boring machine (TBM); Step S2: Create a 3D model of the cutter head; Step S3: Construct a single-layer geological soil model in the discrete element modeling software and import it into the cutterhead model to form a tunneling simulation model; Step S4: Set the cutterhead thrust and rotation speed to perform single-layer geological tunneling simulation and obtain the tunneling speed under different working conditions; Step S5: Establish a mathematical model of single-layer geological tunneling speed with respect to thrust and rotational speed; Step S6: Based on the proportions of each layer in the composite strata The tunneling time in complex strata is calculated using a weighted formula:

[0008]

[0009] In the formula: —The time it takes for a tunnel boring machine to advance 1 meter in the i-th stratum under certain construction conditions, in hours; —The tunneling speed of the tunnel boring machine in the i-th stratum under a certain construction condition, in mm / s; —The time it takes for a tunnel boring machine to advance 1 meter in a composite geological stratum under certain construction conditions, expressed in hours; —The proportion of the i-th stratum in the composite stratum.

[0010] Furthermore, step S3 includes calibrating the soil particle contact parameters, which include normal stiffness per unit area, shear stiffness per unit area, critical normal stress, critical shear stress, and bonding disk radius.

[0011] Furthermore, the contact parameters are calibrated through virtual tests, including uniaxial compression tests or triaxial stress tests, and the error between the simulated uniaxial compressive strength and the measured strength after calibration is ≤5%.

[0012] Furthermore, step S3 specifically includes: Step S31: Create a cube model of 1000mm×1000mm×1000mm; Step S32: Generate a particle bed using Block Factory; Step S33: Import the 3D model of the cutter head and set the contact mechanics parameters.

[0013] Furthermore, the mathematical model for step S5 is as follows:

[0014] in, Thrust, in 10,000 kN; x2 is rotational speed, in rpm. , This represents the stratigraphic correlation coefficient.

[0015] Furthermore, in step S4: Set the simulation time step to 1-2 minutes; The cutter head rotates ≥2 revolutions; The tunneling speed is taken as the average value during the simulation process.

[0016] Furthermore, formation parameters include triaxial pressure, Poisson's ratio, elastic modulus, and unit weight.

[0017] Furthermore, the strata include sandy clayey soil, completely weathered granite, soil-like strongly weathered granite, massive strongly weathered granite, moderately weathered granite, and slightly weathered granite.

[0018] Furthermore, the calibration parameters for the slightly weathered granite satisfy: normal stiffness per unit area = 8.0 × 1 N / m³, shear stiffness per unit area = 8.0 × 1 N / m³, critical normal stress = 8.9 × 1 Pa, critical shear stress = 8.9 × 1 Pa.

[0019] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the method for predicting the tunneling progress of a tunnel boring machine in composite strata.

[0020] Compared with existing technologies, this solution has the following advantages: 1. Improve prediction accuracy: Through EDEM discrete element simulation technology, a large amount of simulation data can be obtained in the early stage of construction, making up for the lack of actual construction data and significantly improving the accuracy of tunnel boring machine progress prediction; 2. Adaptable to complex strata: The weighted calculation method is adopted to estimate the tunneling progress based on the proportion of different strata, which can effectively cope with the impact of strata changes on tunneling efficiency in complex strata and adapt to complex geological conditions; 3. Optimize construction planning: Accurate tunneling progress forecasting provides a reliable progress reference for construction projects, which helps to optimize construction plans, rationally allocate resources, improve construction efficiency, and reduce construction costs; 4. Enhance construction safety: By simulating the tunneling behavior of the tunnel boring machine under different geological conditions, potential construction risks can be identified in time, and measures can be taken in advance to enhance construction safety. 5. Validation and optimization of the model: Comparative analysis of simulation results and field measured data can verify the reliability of the simulation model and provide a basis for further optimization of the model, thereby improving the universality and accuracy of the prediction method. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a model diagram for single-layer geological soil parameter calibration provided by the present invention; Figure 2 This invention provides a graph showing the variation of uniaxial compressive strength of moderately weathered mixed granite with loading time. Figure 3 This is a tunneling model diagram of a tunnel boring machine provided by the present invention; Figure 4 This is a prediction result diagram of the single-layer geological tunneling progress of a tunnel boring machine provided by the present invention; Figure 5 This invention provides a geological map for tunneling in composite strata using a tunnel boring machine. Figure 6 This is a prediction result diagram of the tunneling progress of a shield machine in composite strata, provided by the present invention. Figure 7 This is a flowchart of the method for predicting tunneling in composite strata using a shield machine based on discrete element simulation, as described in this invention. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Reference Figure 7This invention provides a method for predicting the tunneling progress of a tunnel boring machine in complex strata based on discrete element simulation, including: Step S1: Collect stratum parameters for each section of the tunnel boring machine (TBM); Step S2: Create a 3D model of the cutter head; Step S3: Construct a single-layer geological soil model in the discrete element modeling software and import it into the cutterhead model to form a tunneling simulation model; Step S4: Set the cutterhead thrust and rotation speed to perform single-layer geological tunneling simulation and obtain the tunneling speed under different working conditions; Step S5: Establish a mathematical model of single-layer geological tunneling speed with respect to thrust and rotational speed; Step S6: Based on the proportions of each layer in the composite strata The tunneling time in complex strata is calculated using a weighted formula:

[0025]

[0026] In the formula: —The time it takes for a tunnel boring machine to advance 1 meter in the i-th stratum under certain construction conditions, in hours; —The tunneling speed of the tunnel boring machine in the i-th stratum under a certain construction condition, in mm / s; —The time it takes for a tunnel boring machine to advance 1 meter in a composite geological stratum under certain construction conditions, expressed in hours; —The proportion of the i-th stratum in the composite stratum.

[0027] Taking the shield tunneling data of a certain subway shield tunnel section as an example, the details are as follows.

[0028] A method for predicting tunneling progress from single-layer geology to composite strata using EDEM software for single-layer geological simulation and weighted calculation includes the following steps: Step S1: Collect the types of strata in the shield tunneling area on site, and conduct triaxial tests on the soil of each type of strata to obtain parameters such as triaxial pressure, Poisson's ratio, elastic model, and unit weight of each soil stratum.

[0029] Step 2: Create a 3D model of the cutter head in CAD software based on its features.

[0030] Step 3: When simulating the tunneling process of a tunnel boring machine using EDEM software, the soil material parameters first need to be calibrated. This mainly includes the intrinsic parameters of soil particles (such as density, Poisson's ratio, and elastic modulus), and the contact parameters between soil particles and external materials, as well as between soil particles themselves (such as static friction coefficient, dynamic friction coefficient, and coefficient of restitution). In the EDEM model, most of the intrinsic parameters of soil particles are consistent with those of real soil particles, so recalibration is unnecessary. Due to the complex contact characteristics between particles, five bond parameters—Normal Stiffness per unit area, Shear Stiffness per unit area, Critical Normal Stress, Critical Shear Stress, and Bonded Disk Radius—are recalibrated through uniaxial compression tests. The following section details the parameter calibration process using a virtual rock (moderately weathered mixed granite) sample with a uniaxial compressive strength of 34.23 MPa as an example.

[0031] The uniaxial compression test used a 1000mm × 2000mm cylindrical rock specimen for virtual uniaxial compression testing. For rock particle generation, a particle factory was built into EDEM. Particles were first generated within the cylindrical geometry and then compacted using a pressure of 10000N to facilitate subsequent bond formation. After the rock specimen was generated, the particle generation mold was virtualized, and upper and lower pressure plates were set. The uniaxial compression simulation model of the rock is shown in the attached figure. Figure 1 As shown. The uniaxial compression simulation test was conducted strictly according to the indoor uniaxial compression test procedure. The method of applying load was to keep the lower pressure plate stationary and move the upper pressure plate downward at a uniform speed of 2 mm / s. The rock specimen failed after reaching the peak compressive strength.

[0032] In the initial loading stage, the bonds did not break, and the rock specimen was in the elastic deformation stage. As the upper pressure plate moved downwards, the load on the rock specimen increased continuously. When the peak compressive strength of 24.5 MPa was reached, the pressure on the upper pressure plate suddenly dropped from 32.4 MPa to 3.95 MPa. At the same time, a large number of bonds broke instantaneously, and the rock fractured, as shown in the attached figure. Figure 2 As shown.

[0033] In EDEM, rock specimens under different bond parameters were simulated, and the uniaxial compressive strength values ​​of the specimens under each set of parameters were recorded. After multiple modifications of the bond parameters and trial calculations, the project needs to calibrate each rock layer of the shield tunnel strata. The corresponding values ​​of the uniaxial compressive strength of each layer and the bond bond are shown in the table below.

[0034] Table 1 shows the calibration results of the soil parameters for the above strata:

[0035] The EDEM tunneling model is established using the following steps: First, a 1000mm × 1000mm × 1000mm Block model is created. Then, a pre-generated Block Factory is imported into the model to construct a large particle bed. Finally, the 3D model of the tunnel boring machine is imported into the EDEM particle bed model, as shown in the attached figure. Figure 3 As shown.

[0036] Step 4: In the simulation of a single tunneling pass of the tunnel boring machine (TBM), a fixed thrust and rotation speed are set for the cutterhead. Based on the set cutterhead rotation speed, the simulation time step is set to 1-2 minutes to ensure that the cutterhead completes two revolutions. During rotation, the cutterhead contacts the soil particles, forcing them to separate from the particle bed. These separated particles enter the soil chamber through the cutterhead opening and are transported to the outside by a screw conveyor at the bottom of the soil chamber, thus simulating the TBM tunneling process. As tunneling progresses, the changes in the cutterhead's tunneling speed and torque over time are fed back to the simulation system, and the average value is taken as the simulation result. By changing the cutterhead thrust and rotation speed, simulated values ​​of the tunneling speed and cutterhead torque under different thrust and rotation speed conditions are obtained.

[0037] Table 2 shows the simulation results of the tunneling speed of the tunnel boring machine mentioned above:

[0038]

[0039] 32 represents the simulation results of the cutterhead torque of the tunnel boring machine mentioned above:

[0040]

[0041] Step 5: Regression analysis was performed on the tunneling parameters of each stratum using Matlab software. The curve fitting results are shown in Table 3. According to the geological exploration report, the shield tunneling area of ​​rings 307-337 on the left line of the project is mostly composed of soil-like strongly weathered mixed granite. Based on the measured data of shield machine thrust and cutterhead rotation speed of rings 307-337 on the left line of the project, combined with the fitting results of the tunneling speed of soil-like strongly weathered mixed granite, the tunneling progress of the shield machine in this section was predicted and compared with the measured tunneling progress on site. The results are attached. Figure 4 As shown.

[0042] Table 4 shows the fitting results of the tunneling parameters for the above-mentioned strata:

[0043] Step 6: Predicting the tunneling progress of the tunnel boring machine (TBM) in composite strata. This is done using a weighted calculation method based on the proportion of different strata. Specifically, the tunneling progress of the TBM under a specific construction condition in a single stratum is first predicted. Then, based on the proportion of each stratum in the composite stratum, a weighted calculation is performed. Finally, the tunneling progress of the TBM under a specific construction condition in the composite stratum is calculated. The specific calculation formula is as follows:

[0044]

[0045] In the formula: —Time (h) for the tunnel boring machine to excavate 1m in the i-th stratum under certain construction conditions; —The tunneling speed of the tunnel boring machine under a certain construction condition in the i-th stratum, in mm / s; —Time (h) for a tunnel boring machine to advance 1m in a composite geological stratum under certain construction conditions; —The proportion of the i-th stratum in the composite stratum.

[0046] Based on the above formula, the tunneling progress of the tunnel boring machine from ring 1 to ring 334 on the left line of the project was predicted, and compared with the actual measured progress on site. The geological map of the left line of the project is attached. Figure 5 As shown in the attached document. Figure 6 The results show that the tunneling progress predicted by the EDEM simulation data is roughly equal to the actual measured data on site. The significant difference in tunneling progress between the 140th and 200th rings is due to the fact that the tunnel cutters were being maintained on site during that period, resulting in chaotic time records.

[0047] This invention proposes a method for predicting the tunneling progress of a tunnel boring machine (TBM) in complex geological formations based on discrete element method (DEM) simulation, aiming to address the insufficient prediction accuracy of existing technologies under complex geological conditions. This method uses DEM software to perform high-precision simulation of the TBM's single-layer geological tunneling process, acquiring a large amount of basic data. Combined with weighted calculations, the prediction results of the single-layer geological tunneling progress are extended to complex geological formations. Specifically, firstly, geological parameters of the construction section are collected, a three-dimensional model of the cutterhead is established, and imported into DEM software to construct the tunneling model. Subsequently, by setting the cutterhead thrust and rotational speed under different working conditions, single-layer geological tunneling simulation is performed to obtain tunneling speed and cutterhead torque data. Matlab software is used to fit the data, establish a mathematical model, and then perform weighted calculations based on the proportion of each stratum to ultimately predict the tunneling progress in complex geological formations.

[0048] The extensive data presented in the examples demonstrates the significant benefits of this method. First, discrete element method (DEM) simulation technology enables the acquisition of substantial simulation data in the early stages of construction, effectively addressing the prediction accuracy issues caused by insufficient actual construction data. Second, the weighted calculation method accurately addresses the impact of different strata proportions on tunneling efficiency in complex geological formations, adapting to complex geological conditions. Furthermore, this method provides a reliable schedule reference for construction projects, helping to optimize construction plans, rationally allocate resources, improve construction efficiency, and reduce construction costs. Simultaneously, by simulating the tunneling behavior of the tunnel boring machine under different geological conditions, potential risks can be identified in a timely manner, enhancing construction safety. Finally, the comparative analysis of simulation results and on-site measured data verifies the reliability of the model and provides a basis for model optimization, improving the universality and accuracy of the prediction method.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for predicting the tunneling progress of a tunnel boring machine in composite strata based on discrete element simulation, characterized in that, include: Step S1: Collect stratum parameters for each section of the tunnel boring machine (TBM); Step S2: Create a 3D model of the cutter head; Step S3: Construct a single-layer geological soil model in the discrete element modeling software and import it into the cutterhead model to form a tunneling simulation model; Step S4: Set the cutterhead thrust and rotation speed to perform single-layer geological tunneling simulation and obtain the tunneling speed under different working conditions; Step S5: Establish a mathematical model of single-layer geological tunneling speed with respect to thrust and rotational speed; Step S6: Based on the proportions of each layer in the composite strata The tunneling time in complex strata is calculated using a weighted formula: In the formula: —The time it takes for a tunnel boring machine to advance 1 meter in the i-th stratum under certain construction conditions, in hours; —The tunneling speed of the tunnel boring machine in the i-th stratum under a certain construction condition, in mm / s; —The time it takes for a tunnel boring machine to advance 1 meter in a composite geological stratum under certain construction conditions, expressed in hours; —The proportion of the i-th stratum in the composite stratum.

2. The method for predicting the tunneling progress of a tunnel boring machine in composite strata based on discrete element simulation according to claim 1, characterized in that: Step S3 includes calibrating the soil particle contact parameters, which include normal stiffness per unit area, shear stiffness per unit area, critical normal stress, critical shear stress, and bonding disk radius.

3. The method for predicting the tunneling progress of a tunnel boring machine in composite strata based on discrete element simulation according to claim 2, characterized in that: The contact parameters are calibrated through virtual tests, including uniaxial compression tests or triaxial stress tests, and the error between the simulated uniaxial compressive strength and the measured strength after calibration is ≤5%.

4. The method according to claim 1, characterized in that: Step S3 specifically includes: Step S31: Create a cube model of 1000mm×1000mm×1000mm; Step S32: Generate a particle bed using Block Factory; Step S33: Import the 3D model of the cutter head and set the contact mechanics parameters.

5. The method for predicting the tunneling progress of a tunnel boring machine in composite strata based on discrete element simulation according to claim 1, characterized in that: The mathematical model for step S5 is as follows: in, Thrust, in 10,000 kN; x2 is rotational speed, in rpm. , This represents the stratigraphic correlation coefficient.

6. The method for predicting the tunneling progress of a tunnel boring machine in composite strata based on discrete element simulation according to claim 1, characterized in that: In step S4: Set the simulation time step to 1-2 minutes; The cutter head rotates ≥2 revolutions; The tunneling speed is taken as the average value during the simulation process.

7. The method for predicting the tunneling progress of a tunnel boring machine in composite strata based on discrete element simulation according to claim 1, characterized in that: The formation parameters include triaxial pressure, Poisson's ratio, elastic modulus, and unit weight.

8. The method for predicting the tunneling progress of a tunnel boring machine in composite strata based on discrete element simulation according to claim 1, characterized in that: The strata include sandy clay soil, completely weathered granite, soil-like strongly weathered granite, massive strongly weathered granite, moderately weathered granite, and slightly weathered granite.

9. The method for predicting the tunneling progress of a tunnel boring machine in composite strata based on discrete element simulation according to claim 2, characterized in that: The calibration parameters of the slightly weathered granite satisfy: normal stiffness per unit area = 8.0 × 1 N / m³, shear stiffness per unit area = 8.0 × 1 N / m³, critical normal stress = 8.9 × 1 Pa, critical shear stress = 8.9 × 1 Pa.

10. A computer-readable storage medium storing a computer program, characterized in that, When the program is executed by the processor, it implements the method for predicting the tunneling progress of a tunnel boring machine in composite strata as described in any one of claims 1-9.

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