Method, device and processing equipment for constructing shield tunneling model in heterogeneous sand and gravel strata

Abstract

The present invention provides a method, device and processing equipment for constructing a shield tunneling model in a heterogeneous sand and gravel stratum. The construction method includes: constructing a finite element model of the shield structure according to preset shield construction parameters, where the finite element model of the shield structure includes a stratum model and a shield support mechanism model, and the stratum model includes an intermediate stratum, a bearing layer and a bottom layer; obtaining the size data and volume of the intermediate stratum, and constructing a finite element model of heterogeneous aggregate accumulation based on the size data and volume of the intermediate stratum; first merging the finite element model of heterogeneous aggregate accumulation with the intermediate stratum of the finite element model of the shield structure, and then defining material properties, setting contact conditions and interaction conditions for the merged model to construct a shield tunneling model in a heterogeneous sand and gravel stratum. The construction method provided by the present invention comprehensively considers the characteristics of heterogeneous strata and seepage effects, and the constructed shield tunneling model can be applied to the analysis of complex stratum conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of geotechnical engineering, and particularly relates to a method, device and processing equipment for constructing a shield tunneling model for heterogeneous sand and gravel strata. Background Art

[0002] Shield method, mining method, open cut construction and cut-and-cover construction are common means for underground tunnel construction. Among them, the shield method, due to its high degree of mechanization, high construction efficiency, environmental friendliness and other characteristics, can effectively reduce the impact on the surrounding environment when applied in densely built-up urban areas, and can adjust construction parameters in real time to adapt to various geological conditions. Therefore, it is widely used in urban tunnel construction. Although the shield method has many advantages, it still faces many challenges under complex stratum conditions, especially when dealing with multiple complex strata, such as soft soil, sand and gravel mixed layer, hard rock and water-rich strata, etc. Shield construction is easily affected by seepage, water pressure and stratum inhomogeneity, resulting in problems such as stratum deformation, leakage and collapse. Therefore, the safety and stability control of shield construction has always been a research hotspot in the academic and engineering fields.

[0003] In the current modeling research on shield construction, the soil model assumes that the stratum is homogeneous or layer-wise homogeneous. Although this assumption simplifies the analysis process, it cannot accurately reflect the actual situation under complex stratum conditions. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for constructing a shield tunneling model for heterogeneous sand and gravel strata that comprehensively considers the characteristics of heterogeneous strata and seepage effects. The shield tunneling model constructed by using this construction method can be applied to the analysis of complex stratum conditions, providing a theoretical basis and technical support for construction parameter optimization and safety control.

[0005] In a first aspect, the present invention provides a method for constructing a shield tunneling model for heterogeneous sand and gravel strata. The construction method includes the following steps: Step S10: According to preset shield construction parameters, a finite element model of the shield structure is constructed. The finite element model of the shield structure includes a stratum model and a shield support mechanism model. Along the height direction of the stratum model, the stratum model includes an intermediate stratum, a bearing layer located above the intermediate stratum, and a bottom layer located below the intermediate stratum. A tunnel is excavated in the intermediate stratum; Step S20: Obtain the size data and volume of the intermediate stratum, and construct a finite element model of heterogeneous aggregate accumulation based on the size data and volume of the intermediate stratum. And the sum of the volumes of all the aggregates included in the finite element model of heterogeneous aggregate accumulation is 30% to 40% of the volume of the intermediate stratum; Step S30: First, merge the finite element model of heterogeneous aggregate accumulation with the intermediate stratum of the finite element model of the shield structure, and then define material properties, set contact conditions and interaction conditions for the merged model to construct a shield tunneling model for heterogeneous sand and gravel strata. The intermediate stratum of the shield tunneling model for heterogeneous sand and gravel strata is composed of soil and aggregates.

[0006] In a specific embodiment, the bearing layer is a soft stratum, the bottom layer is a dense stratum, and the intermediate stratum is a sand and gravel stratum.

[0007] In a specific embodiment, the thickness ratio of the bearing layer, the intermediate stratum and the bottom layer is: (3 - 5):(4 - 6):(10 - 12).

[0008] In a specific embodiment, the step of constructing a finite element model of heterogeneous aggregate accumulation based on the size data and volume of the intermediate stratum includes: Step (1): Generate a virtual space based on the size data of the intermediate stratum. The virtual space has the same size data as the intermediate stratum; Step (2): Obtain the geometric model of the original aggregate. Based on the geometric model of the original aggregate as the basic model, use a random function to generate random aggregate geometric models with different particle sizes in the virtual space, and randomly rotate and move the random aggregate geometric models to control that adjacent random aggregate geometric models do not overlap, to obtain a first three-dimensional discrete element model of aggregate accumulation. The first three-dimensional discrete element model of aggregate accumulation includes a multi-level graded aggregate model set, and the volume fraction of each level of graded aggregate model set satisfies a preset condition; Step (3): On the premise of keeping the central coordinates of each random aggregate geometric model unchanged, scale down each random aggregate geometric model by a preset ratio in equal proportion to obtain a second three-dimensional discrete element model of aggregate accumulation; Step (4): Through file format conversion, convert the second three-dimensional discrete element model of aggregate accumulation into the finite element model of heterogeneous aggregate accumulation.

[0009] In a specific embodiment, both the first aggregate accumulation three-dimensional discrete element model in step (2) and the second aggregate accumulation three-dimensional discrete element model in step (3) are constructed using the PFC3D software. Step (4) includes: step (a), exporting the second aggregate accumulation three-dimensional discrete element model as multiple STL files, and each STL file also carries the position information of the random aggregate geometric model; step (b), batch importing the STL files into MATLAB for data processing to obtain multiple IGES files; step (c), importing all the IGES files into Abaqus, and batch reading the IGES files through the Abaqus Python script to convert and obtain the heterogeneous aggregate accumulation finite element model.

[0010] In a specific embodiment, the multi-level graded aggregate model set includes a very large-sized aggregate model set with an equivalent particle size range of 3.8 m to 5 m, a large-sized aggregate model set with an equivalent particle size range of 2.8 m to 3.8 m, a medium-sized aggregate model set with an equivalent particle size range of 1.8 m to 2.8 m, and a small-sized aggregate model set with an equivalent particle size range of 1.0 m to 1.8 m.

[0011] In a specific embodiment, the shield support mechanism model includes a shield shell model for supporting the inner wall of the tunnel, a grouting layer model located within the shield shell model, and a lining segment model located within the grouting layer model.

[0012] In a specific embodiment, the definition of material properties includes: defining the elastic modulus of the aggregate, using a coupled elastoplastic model for the soil in the intermediate formation and defining the permeability coefficient and deformation characteristics of the soil, defining the elastic modulus, Poisson's ratio, yield criterion, cohesion, and internal friction angle of the intermediate formation, setting the shield shell model and the lining segment model in the shield support mechanism model to an impermeable condition, and defining mechanical parameters; the setting of the contact conditions includes the contact setting between the intermediate formation and the bottom layer, the contact setting between the intermediate formation and the bearing layer, the contact setting between the soil in the intermediate formation and the aggregate, the contact setting between the components in the shield support mechanism model, and the contact setting between the shield support mechanism model and the intermediate formation; the setting of the interaction conditions includes introducing a seepage field in the soil area of the intermediate formation and defining the pore pressure distribution of water and the coupling relationship between the pore pressure distribution of water and the mechanical behavior of the intermediate formation.

[0013] Second, the present invention provides a device for constructing a shield tunneling model for a heterogeneous sand and gravel formation. The construction device includes:

[0014] The first construction module is used to construct a finite element model of the shield structure according to preset shield construction parameters. The finite element model of the shield structure includes a formation model and a shield support mechanism model. Along the height direction of the formation model, the formation model includes an intermediate formation, a bearing layer located above the intermediate formation, and a bottom layer located below the intermediate formation. A tunnel is excavated in the intermediate formation. The second construction module is used to obtain the size data and volume of the intermediate formation, and construct a finite element model of heterogeneous aggregate accumulation based on the size data and volume of the intermediate formation. The sum of the volumes of all the aggregates included in the finite element model of heterogeneous aggregate accumulation is 30% - 40% of the volume of the intermediate formation. The third construction module is used to first merge the finite element model of heterogeneous aggregate accumulation with the intermediate formation of the finite element model of the shield structure, and then define material properties, set contact conditions and interaction conditions for the merged model to construct a shield tunneling model of heterogeneous sand and gravel formation. The intermediate formation of the shield tunneling model of heterogeneous sand and gravel formation is composed of soil and aggregates.

[0015] In a third aspect, the present invention provides a processing device, which includes: a processor and a memory. A computer program is stored in the memory. When the processor executes the computer program, the processing device implements the construction method described above.

[0016] The beneficial effects of the present invention at least include:

[0017] 1. The method for constructing a shield tunneling model for heterogeneous sand and gravel strata provided by the present invention includes: Step S10: Construct a finite element model of the shield structure according to preset shield construction parameters. The finite element model of the shield structure includes a stratum model and a shield support mechanism model. Along the height direction of the stratum model, the stratum model includes an intermediate stratum, a bearing layer located above the intermediate stratum, and a bottom layer located below the intermediate stratum. The tunnel is excavated in the intermediate stratum; Step S20: Obtain the size data and volume of the intermediate stratum, and construct a finite element model of heterogeneous aggregate accumulation based on the size data and volume of the intermediate stratum. The sum of the volumes of all the aggregates included in the finite element model of heterogeneous aggregate accumulation is 30% - 40% of the volume of the intermediate stratum; Step S30: First, merge the finite element model of heterogeneous aggregate accumulation with the intermediate stratum of the finite element model of the shield structure, and then define material properties, set contact conditions and interaction conditions for the merged model to construct a shield tunneling model for heterogeneous sand and gravel strata. The intermediate stratum of the shield tunneling model for heterogeneous sand and gravel strata is composed of soil and aggregates. The construction method of the present invention fully considers the characteristics such as complex stratum particle gradation, significant permeability change, and uneven mechanical parameters. By merging the finite element model of heterogeneous aggregate accumulation with the intermediate stratum of the finite element model of the shield structure, the constructed shield tunneling model for heterogeneous sand and gravel strata can dynamically simulate the stratum response and stability change during the shield tunneling process, analyze key influencing factors such as shield driving force, earth pressure, and seepage pressure, and provide a theoretical basis and technical support for construction parameter optimization and safety control.

[0018] 2. The present invention batch generates a random aggregate geometric model through PFC software, and combines MATLAB tools to optimize and convert data formats to ensure compatibility with the Abaqus platform.

[0019] 3. The present invention establishes a mapping relationship between the microscopic structure and the macroscopic mechanical properties through finite element simulation technology, can accurately transfer the microscopic gradation characteristics to the macroscopic analysis, supports the simulation of the deformation and stress distribution of complex strata during the shield propulsion process, and provides an accurate data basis for construction optimization and mechanical analysis.

[0020] 4. The distribution of the random aggregates in the first aggregate accumulation three-dimensional discrete element model constructed by the present invention conforms to the Gaussian distribution, that is, the aggregate density in the tunnel center area is higher, and the aggregate density gradually decreases away from the shield tunneling area. This distribution method can ensure the full filling of aggregates in the tunnel core area while reducing the number of aggregates in the edge area, reducing the calculation amount, and improving the calculation efficiency.

[0021] In addition to the purposes, features, and advantages described above, the present invention has other purposes, features, and advantages. The following will refer to the drawings for a further detailed description of the present invention. Description of the Drawings

[0022] Figure 1 Schematic diagram of the step process of the method for constructing a shield tunneling model in a heterogeneous sand and gravel formation provided by an embodiment of the present invention;

[0023] Figure 2 Finite element model diagram of the shield structure constructed by the present invention;

[0024] Figure 3 Three-dimensional discrete element model diagram of the first aggregate accumulation constructed by the present invention;

[0025] Figure 4 Schematic diagram of the simulation of the internal structure of the shield tunneling model in a heterogeneous sand and gravel formation constructed by the present invention;

[0026] Figure 5 Module diagram of the device for constructing a shield tunneling model in a heterogeneous sand and gravel formation provided by another embodiment of the present invention. Detailed Description of the Invention

[0027] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] The method for constructing a shield tunneling model in a heterogeneous sand and gravel formation provided by the present invention is an improvement on the technical problem that the existing homogeneous formation cannot simulate complex formations, resulting in low accuracy of simulation results. By setting the formation as a three-layer structure and filling the middle formation with aggregates of different gradation particle sizes to form a heterogeneous sand and gravel formation, the constructed model not only takes into account the influence of complex formations on simulation results, but also can introduce a seepage field to consider the influence of seepage and water pressure on shield construction, making the simulation results more accurate.

[0029] Please refer to Figure 1 , the present invention provides a method for constructing a shield tunneling model in a heterogeneous sand and gravel formation, and the construction method includes the following steps:

[0030] Step S10: According to the preset shield construction parameters, construct a finite element model of the shield structure. The finite element model of the shield structure includes a formation model 200 and a shield support mechanism model 300. Along the height direction of the formation model 200, the formation model 200 includes an intermediate formation 201A, a bearing layer 202 located above the intermediate formation 201A, and a bottom layer 203 located below the intermediate formation. The tunnel is excavated in the intermediate formation 201A.

[0031] In the present invention, the preset shield construction parameters include the size of the shield structure and the diameter and burial depth ratio of the tunnel to be excavated.

[0032] In the present invention, the dimensions of the shield structure are determined based on the dimensions of the stratum model and are the same as those of the stratum model, that is, the length of the stratum model is the length of the shield structure, the width of the stratum model is the width of the shield structure, and the thickness / depth / height of the stratum model is the height of the shield structure.

[0033] Preferably, the shield support mechanism model 300 includes a shield shell model for supporting the inner wall of the tunnel, a grouting layer model located within the shield shell model, and a lining segment model located within the grouting layer model.

[0034] Preferably, the bearing layer 202 is a soft stratum, the bottom layer 203 is a dense stratum, and the intermediate stratum 201A is a sandy gravel stratum.

[0035] Preferably, the thickness ratio of the bearing layer, the intermediate stratum, and the bottom layer is: (3 - 5):(4 - 6):(10 - 12).

[0036] In actual construction projects, the shield area often traverses multiple geological units (such as fill strata, silt strata, gravel strata, pebble strata, or weathered rock strata, etc.). In the present invention, the stratum model is set as a three-layer structure. On the one hand, it makes the stratum model closer to the actual engineering construction situation, which can improve the accuracy of the simulation results; on the other hand, the three-layer structure can flexibly replace any layer of soil material, thus meeting the construction simulation requirements under different site conditions. For example, in a certain project, the bottom layer is strongly weathered rock or completely weathered mudstone, and only the parameters of the bottom layer need to be changed to carry out the adaptability simulation, without the need to re-establish the overall model.

[0037] In the present invention, the finite element model of the shield structure is constructed using Abaqus software. Specifically: the entire modeling process adopts a three-dimensional solid model, and at the same time combines the composite modeling method of shell elements and solid elements to ensure the calculation accuracy and modeling efficiency.

[0038] In the present invention, the total size of the shield model structure is designed as 80m (length) × 50m (width) × 40m (depth), the diameter D of the tunnel to be excavated is 6.4m, and the tunnel burial depth ratio is 2D, that is, 12.8m.

[0039] The stratum structure is divided into a three-layer structure. The thickness of the bearing layer is 7.8m, and its index parameters are: unit weight is 18 - 20kN / m 3 , elastic modulus is 4 - 6MPa, cohesion is 5 - 15kPa, and internal friction angle is 10 - 15 degrees; the thickness of the intermediate stratum is 10m, and its index parameters include: unit weight is 20kN / m 3 , compression modulus is 25MPa, cohesion is 0kPa, and internal friction angle is 36 degrees; the thickness of the bottom layer is 22.2m, and its index parameters include: unit weight is 23.9kN / m 3, the compression modulus is 43 MPa, the cohesion is 0 kPa, and the internal friction angle is 45 degrees.

[0040] In the present invention, the shield shell model in the shield support mechanism model is set as a shell element with a radius of 3.2 m, which is used to support the inner wall of the tunnel; the grouting layer is set as an annular solid structure with an outer diameter of 3.2 m and an inner diameter of 3.0 m, which plays a role in simulating support and anti-seepage; the lining segment is set as an annular solid structure with an outer diameter of 3.0 m and an inner diameter of 2.7 m. The lining segment serves as the final support structure to provide overall stability.

[0041] Please refer to Figure 2 , Figure 2 which is the finite element model diagram of the shield structure constructed for the present invention.

[0042] Step S20: Obtain the size data and volume of the intermediate formation, and construct a heterogeneous aggregate packing finite element model based on the size data and volume of the intermediate formation. The sum of the volumes of all the aggregates included in the heterogeneous aggregate packing finite element model is 30% - 40% of the volume of the intermediate formation.

[0043] In an alternative embodiment, the step of constructing a heterogeneous aggregate packing finite element model based on the size data and volume of the intermediate formation includes:

[0044] Step (1): Generate a virtual space based on the size data of the intermediate formation. The virtual space has the same size data as the intermediate formation.

[0045] In the present invention, the size of the intermediate formation is 80 m (length) × 50 m (width) × 10 m (height). In this way, the size of the virtual space is also 80 m (length) × 50 m (width) × 10 m (height).

[0046] Step (2): Obtain the geometric model of the original aggregate. Based on the geometric model of the original aggregate, use a random function to generate random aggregate geometric models with different particle sizes in the virtual space, and randomly rotate and move the random aggregate geometric models to control that adjacent random aggregate geometric models do not overlap, thereby obtaining a first aggregate packing three-dimensional discrete element model. The first aggregate packing three-dimensional discrete element model includes a multi-level graded aggregate model set, and the volume fraction of each level of graded aggregate model set satisfies a preset condition.

[0047] It should be noted that in the present invention, the particle size of the aggregate refers to the equivalent particle size of the aggregate.

[0048] In the present invention, the first aggregate packing three-dimensional discrete element model is constructed using PFC3D software.

[0049] In an alternative embodiment, a geometric model of the original aggregate is constructed based on the selected real aggregate.

[0050] This step specifically includes: randomly selecting real aggregates, and obtaining the geometric model of the real aggregates by the image method or the three-dimensional scanning method.

[0051] It should be noted that in the present invention, both the image method and the three-dimensional scanning method are prior arts.

[0052] In an alternative embodiment, the random function is:

[0053] .

[0054] Wherein, is the i-th aggregate particle size generated; is the set minimum particle size, with a value of 1; is the set maximum particle size, with a value of 5; is a random number between 0 and 1.

[0055] Using this random function to determine the particle sizes of aggregates of each gradation can ensure that the random distribution of particle sizes meets the inhomogeneous characteristics.

[0056] In the present invention, understanding the geometric model of the original aggregate as the basic model means that the shapes of the geometric models of random aggregates with different particle sizes generated subsequently are similar to the shape of the geometric model of the original aggregate, that is, the geometric model of the random aggregate is obtained by enlarging or reducing the geometric model of the original aggregate, and the magnification or reduction factor = the particle size calculated by the random function / the equivalent particle size of the original aggregate.

[0057] In an alternative embodiment, the multi-gradation aggregate model set includes a super-large particle size aggregate model set with an equivalent particle size range of 3.8m to 5m, a large particle size aggregate model set with an equivalent particle size range of 2.8m to 3.8m, a medium particle size aggregate model set with an equivalent particle size range of 1.8m to 2.8m, and a small particle size aggregate model set with an equivalent particle size range of 1m to 1.8m.

[0058] In the present invention, according to the engineering requirements, the aggregates are divided into different gradation ranges. Limited by the huge stacking volume and complex composition of actual engineering materials, the more the number of aggregates selected by BBS, the better. Too many will cause the computer to fail to meet the requirements, and compared with the overall size of the model, if the aggregates are too small, the advantages of inhomogeneity cannot be reflected. Therefore, the aggregates are divided into different gradation ranges, the minimum particle size is set to 1m, and the maximum particle size is set to 5m to ensure that the particle sizes meet the engineering requirements and reduce the calculation complexity.

[0059] In an alternative embodiment, the volume fraction of each graded aggregate model set satisfying the preset condition means that, taking the sum of the volumes of all the aggregates in the three-dimensional discrete element model of the first aggregate packing as 100%, the volume fraction corresponding to the extra-large particle size aggregate model set is between 20% and 30%, the volume fraction corresponding to the large particle size aggregate model set is between 20% and 30%, the volume fraction corresponding to the medium particle size aggregate model set is between 20% and 30%, and the volume fraction corresponding to the small particle size aggregate model set is between 10% and 20%.

[0060] In an embodiment of the present invention, the volume fraction of each graded aggregate model set satisfying the preset condition means that the sum of the volumes of all the aggregates in the extra-large particle size aggregate model set is 28.1% of the total volume, the sum of the volumes of all the aggregates in the large particle size aggregate model set is 25.1% of the total volume, the sum of the volumes of all the aggregates in the medium particle size aggregate model set is 28.6% of the total volume, and the sum of the volumes of all the aggregates in the small particle size aggregate model set is 18.2% of the total volume, where the total volume is the sum of the volumes of all the aggregates in the three-dimensional discrete element model of the first aggregate packing.

[0061] In other embodiments, the volume fractions of different graded aggregate model sets can also be other values. For example, the volume fraction corresponding to the extra-large particle size aggregate model set can also be 24%, 26%, 27%, etc., the volume fraction corresponding to the large particle size aggregate model set can also be 23%, 25%, 27%, etc., the volume fraction corresponding to the medium particle size aggregate model set can also be 26%, 28.5%, 29%, etc., and the volume fraction corresponding to the small particle size aggregate model set can also be 17.5%, 18%, 18.5%, etc.

[0062] In an alternative embodiment, the sum of the volumes of all the aggregates included in the heterogeneous aggregate packing finite element model is 40% of the volume of the intermediate formation.

[0063] For ease of understanding, an example is given based on the optional data above. Assume the volume of the intermediate formation is 80m × 50m × 10m = 4000m 3 , then the sum of the volumes of all the aggregates included in the heterogeneous aggregate packing finite element model = 4000 × 40% = 1600m 3 , so the sum of the volumes of all the aggregates in the extra-large particle size aggregate model set = 1600 × 28.1%, the sum of the volumes of all the aggregates in the large particle size aggregate model set = 1600 × 25.1%, the sum of the volumes of all the aggregates in the medium particle size aggregate model set = 1600 × 28.6%, and the sum of the volumes of all the aggregates in the small particle size aggregate model set = 1600 × 18.2%.

[0064] In another alternative embodiment, the volume fraction of each graded aggregate model set satisfying the preset condition can also be that, taking the volume of the virtual space as 100%, the volume fractions corresponding to the extra-large particle size aggregate model set, the large particle size aggregate model set, the medium particle size aggregate model set, and the small particle size aggregate model set are respectively defined.

[0065] For ease of understanding, by way of example, if taking the volume of the virtual space as 100%, assuming that the sum of the volumes of all the aggregates included in the heterogeneous aggregate packing finite element model is 40% of the volume of the intermediate formation, then the volume fraction corresponding to the extra-large particle size aggregate model set = 40% × 28.1%, the volume fraction corresponding to the large particle size aggregate model set = 40% × 25.1%, the volume fraction corresponding to the medium particle size aggregate model set = 40% × 28.6%, and the volume fraction corresponding to the small particle size aggregate model set = 40% × 18.2%.

[0066] Please refer to Figure 3 , Figure 3 , which is the first three-dimensional discrete element model diagram of aggregate packing constructed for the present invention.

[0067] Step (3): On the premise of keeping the central coordinates of each of the random aggregate geometric models unchanged, each of the random aggregate geometric models is scaled down in equal proportion according to a preset ratio to obtain a second three-dimensional discrete element model of aggregate packing.

[0068] In the present invention, the corresponding equal-proportion scaling operation of this step is carried out in the PFC3D software.

[0069] During the PFC3D calculation process, in order to reduce the calculation error and ensure the stability of the aggregate packing structure, the volumes of all the random aggregates are uniformly fine-tuned to reduce the calculation error, while keeping the central coordinates of each of the random aggregate geometric models unchanged to ensure the integrity of the aggregate structure. The adjustment formula is as follows:

[0070] .

[0071] Wherein, The adjusted volume of the i th random aggregate, V i is the initial volume of the i th random aggregate, δ is the set scaling ratio.

[0072] In the present invention, δ = 0.001 to minimize the error of the volume fraction.

[0073] In the present invention, the central coordinates of the adjusted random aggregates remain unchanged, and only the volume is slightly adjusted to avoid boundary problems caused by precision errors. This adjustment method is applicable to all random aggregates, rather than only the random aggregates at the boundary of the computational domain, ensuring that all random aggregates can still be correctly recognized after being imported into Abaqus and are consistent with the calculation results in PFC3D.

[0074] Step (4): Convert the three-dimensional discrete element model of the second aggregate accumulation into the finite element model of the heterogeneous aggregate accumulation through file format conversion.

[0075] In an alternative embodiment, step (4) includes:

[0076] Step (a): Export the three-dimensional discrete element model of the second aggregate accumulation as multiple STL files, and each STL file also carries the position information of the random aggregate geometric model.

[0077] It can be understood that each random aggregate geometric model is separately saved as an STL file.

[0078] The position and volume distribution of the random aggregates have been set during the PFC3D calculation and stored as database information. Therefore, when constructing the finite element model of the heterogeneous aggregate accumulation, these coordinate data can be directly called without the need for additional placement operations.

[0079] Step (b): Batch import the STL files into MATLAB for data processing to obtain multiple IGES files.

[0080] Step (c): Import all the IGES files into Abaqus, and batch read the IGES files through the Abaqus Python script to convert and obtain the finite element model of the heterogeneous aggregate accumulation.

[0081] By using the file format conversion method provided by the present invention, it can be ensured that the random aggregate geometric model can be correctly imported and is consistent with the PFC3D calculation results.

[0082] Step S30: First, merge the finite element model of the heterogeneous aggregate accumulation with the intermediate formation of the finite element model of the shield structure, and then define the material properties, set the contact conditions and interaction conditions for the merged model to construct a non-homogeneous sand and gravel formation shield tunneling model. The intermediate formation 201B of the non-homogeneous sand and gravel formation shield tunneling model is composed of soil and aggregates.

[0083] In the present invention, step S30 is operated using Abaqus software.

[0084] In an alternative embodiment, the operation of merging the heterogeneous aggregate accumulation finite element model with the intermediate formation of the finite element model of the shield structure is specifically as follows: performing a Boolean operation to merge the heterogeneous aggregate accumulation finite element model with the intermediate formation of the finite element model of the shield structure, and disabling the soil mass that overlaps with the aggregate in the intermediate formation.

[0085] In an alternative embodiment, the definition of material properties includes: defining the elastic modulus of the aggregate; using an elasto-plastic model with seepage and coupling for the soil mass in the intermediate formation, and defining the permeability coefficient and deformation characteristics of the soil mass; defining the elastic modulus, Poisson's ratio, yield criterion, cohesion, and internal friction angle of the intermediate formation; setting the shield shell model and the lining segment model in the shield support mechanism model to impermeable conditions, and defining mechanical parameters, where the mechanical parameters include the elastic modulus and density.

[0086] In the present invention, the elastic modulus of the aggregate is between 10,000 MPa and 30,000 MPa, belonging to high-stiffness elastic parameters.

[0087] In an alternative embodiment, the setting of the contact conditions includes the contact setting between the intermediate formation and the bottom layer, the contact setting between the intermediate formation and the bearing layer, the contact setting between the soil mass of the intermediate formation and the aggregate, the contact setting between the components in the shield support mechanism model, and the contact setting between the shield support mechanism model and the intermediate formation.

[0088] In an alternative embodiment, the setting of the interaction conditions includes introducing a seepage field in the soil mass region of the intermediate formation, and defining the pore pressure distribution of water and the coupling relationship between the pore pressure distribution of water and the mechanical behavior of the intermediate formation.

[0089] In the present invention, seepage refers to the flow of fluid in a porous medium.

[0090] In the present invention, the mechanical behavior of the intermediate formation includes deformation, failure, and stability.

[0091] Please refer to Figure 4 , Figure 4 which is a schematic diagram of the internal structure of the shield tunneling model for the heterogeneous sand and gravel formation constructed according to the present invention.

[0092] Dividing the mesh of the shield tunneling model for the heterogeneous sand and gravel formation constructed according to the present invention, applying boundary conditions and loading processes, including the actions of shield propulsion force, earth pressure, and seepage pressure, etc., and performing calculation and analysis, can output the results of formation deformation and force response for analyzing the stability and safety during the shield construction process.

[0093] Please refer to Figure 5, the present invention also provides a device 100 for constructing a shield tunneling model for heterogeneous sand and gravel strata. The construction device 100 includes:

[0094] A first construction module 101, configured to construct a finite element model of a shield structure according to preset shield construction parameters. The finite element model of the shield structure includes a stratum model and a shield support mechanism model. Along the height direction of the stratum model, the stratum model includes an intermediate stratum, a bearing layer located above the intermediate stratum, and a bottom layer located below the intermediate stratum. A tunnel is excavated in the intermediate stratum.

[0095] A second construction module 102, configured to obtain the size data and volume of the intermediate stratum, and construct a finite element model of heterogeneous aggregate accumulation based on the size data and volume of the intermediate stratum. And the sum of the volumes of all the aggregates included in the finite element model of heterogeneous aggregate accumulation is 30% - 40% of the volume of the intermediate stratum.

[0096] A third construction module 103, configured to first merge the finite element model of heterogeneous aggregate accumulation with the intermediate stratum of the finite element model of the shield structure, and then define material properties, set contact conditions and interaction conditions for the merged model, so as to construct a shield tunneling model for heterogeneous sand and gravel strata. The intermediate stratum of the shield tunneling model for heterogeneous sand and gravel strata is composed of soil and aggregates.

[0097] Those skilled in the art can clearly understand that for the convenience and brevity of description, the working process of the above-described construction device can refer to the content in the foregoing method embodiments, and will not be repeated here.

[0098] The present invention also provides a processing device, Figure 5 The shown construction device can be arranged in this processing device. The processing device includes a memory, a processor, a communication interface and a bus. Among them, the memory, the processor and the communication interface are communicatively connected to each other through the bus. And this computer device can include multiple processors, so as to implement the functions of the above different modules through different processors.

[0099] The memory can be a read-only memory, a static storage device, a dynamic storage device or a random access memory. The memory can store executable code sequences. When the executable code stored in the memory is executed by the processor, the processor and the communication interface are used to execute the method for constructing a shield tunneling model for heterogeneous sand and gravel strata provided in the embodiments of the present application. The memory can also include other software modules and data required for other running processes such as an operating system. And the operating system can be LINUX, UNIX, WINDOWS™, etc.

[0100] The processor may be a general - purpose central processing unit (CPU), a microprocessor, an application - specific integrated circuit (ASIC), a graphics processing unit (GPU), or one or more integrated circuits.

[0101] The processor may also be an integrated circuit chip with signal - processing capabilities. In the implementation process, some or all of the functions of the heterogeneous sand - gravel stratum shield tunneling model construction method of this application can be completed by the integrated logic circuit in the hardware of the processor or instructions in software form. The above - mentioned processor may also be a general - purpose processor, a digital signal processing (DSP), an application - specific integrated circuit (ASIC), a field - programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general - purpose processor may be a microprocessor, or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of this application can be directly embodied as being executed and completed by a hardware decoding processor, or executed and completed by a combination of hardware and software modules in the decoding processor. The software module may be located in a mature storage medium in the art, such as a random access memory, a flash memory, a read - only memory, a programmable read - only memory, or an electrically erasable programmable memory, a register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the heterogeneous sand - gravel stratum shield tunneling model construction method of the embodiments of this application.

[0102] The communication interface uses a transceiver module such as, but not limited to, a transceiver to achieve communication between the computer device and other devices or communication networks. For example, the communication interface may be any one or any combination of the following devices: a network interface (such as an Ethernet interface), a wireless network card, and other devices with network access functions.

[0103] The bus may include a path for transmitting information between various components of the computer device (for example, the memory, the processor, the communication interface).

[0104] A communication path is established between each of the above - mentioned computer devices through a communication network. Each computer device is used to implement part of the functions of the heterogeneous sand - gravel stratum shield tunneling model construction method provided in the embodiments of this application. Any computer device may be a computer device (for example: a server) in a cloud data center, or a computer device in an edge data center, etc.

[0105] The descriptions of the processes corresponding to the above-mentioned various drawings each have their own focuses. For the parts not detailed in a certain process, reference can be made to the relevant descriptions of other processes.

[0106] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product for providing the data synchronization cloud service includes one or more computer instructions. When these computer program instructions are loaded and executed on a computer device, the processes or functions of the method for constructing a shield tunneling model for heterogeneous sand and gravel strata provided by the embodiments of the present application are implemented in whole or in part.

[0107] The processing device can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from a website, a computer, a server, or a data center to another website, a computer, a server, or a data center by wire (such as coaxial cable, optical fiber, digital subscriber line) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium stores computer program instructions for providing the data synchronization cloud service.

[0108] The above content is a further detailed description of the present invention in combination with specific preferred implementation manners. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions and substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for constructing a shield tunneling model in a heterogeneous sandstone stratum, characterized in that: The construction method comprises the following steps: Step S10, constructing a finite element model of a shield structure according to preset shield construction parameters, wherein the finite element model of the shield structure includes a stratum model and a shield support mechanism model, wherein along the height direction of the stratum model, the stratum model includes an intermediate stratum, a bearing layer located above the intermediate stratum, and a bottom layer located below the intermediate stratum, and the tunnel is excavated in the intermediate stratum; Step S20, obtaining the size data and volume of the intermediate stratum, and constructing a heterogeneous aggregate accumulation finite element model based on the size data and volume of the intermediate stratum, wherein the sum of the volumes of all aggregates included in the heterogeneous aggregate accumulation finite element model is 30% to 40% of the volume of the intermediate stratum; Step S30: first merge the finite element model of the heterogeneous aggregate accumulation with the intermediate stratum of the finite element model of the shield structure, and then define the material properties of the merged model, set contact conditions and interaction conditions, and construct a heterogeneous sand and gravel stratum shield tunneling model, wherein the intermediate stratum of the heterogeneous sand and gravel stratum shield tunneling model consists of soil and aggregate.

2. The method for constructing a shield tunneling model in a heterogeneous sandstone stratum according to claim 1, characterized in that: The bearing layer is a soft stratum, the bottom layer is a dense stratum, and the middle stratum is a sandstone stratum.

3. The method for constructing a shield tunneling model in a heterogeneous sandstone stratum according to claim 2, characterized in that: The thickness ratio of the bearing layer, the intermediate layer and the bottom layer is: A:B:C, wherein the value range of A is 3-5, the value range of B is 4-6, and the value range of C is 10-12.

4. The method for constructing a shield tunneling model in a heterogeneous sandstone stratum according to claim 1, characterized in that: The step of constructing a finite element model of heterogeneous aggregate accumulation based on the size data and volume of the intermediate stratum comprises: Step (1), generating a virtual space based on the dimension data of the intermediate stratum, wherein the virtual space has the same dimension data as the intermediate stratum; Step (2), obtaining a geometric model of original aggregate, taking the geometric model of original aggregate as a basic model, generating random aggregate geometric models of different particle sizes in the virtual space by using a random function, and randomly rotating and moving the random aggregate geometric models to control adjacent random aggregate geometric models not to overlap, thereby obtaining a first aggregate stacking three-dimensional discrete element model, wherein the first aggregate stacking three-dimensional discrete element model includes a multi-level graded aggregate model set, and the volume fraction of each level graded aggregate model set meets a preset condition; Step (3), under the premise of keeping the central coordinates of each of the random aggregate geometric models unchanged, each of the random aggregate geometric models is proportionally reduced according to a preset ratio to obtain a second aggregate stacking three-dimensional discrete element model; Step (4): converting the second aggregate stacking three-dimensional discrete element model into the heterogeneous aggregate stacking finite element model through file format conversion.

5. The method for constructing a shield tunneling model in a heterogeneous sandstone stratum according to claim 4, characterized in that: The first aggregate stacking three-dimensional discrete element model in step (2) and the second aggregate stacking three-dimensional discrete element model in step (3) are both constructed using PFC3D software, and step (4) includes: Step (a), exporting the second aggregate stacking three-dimensional discrete element model as a plurality of STL files, wherein each STL file also carries position information of the random aggregate geometric model; Step (b), batch importing the STL files into MATLAB for data processing to obtain multiple IGES files; Step (c), importing all IGES files into Abaqus, batch reading IGES files through Abaqus Python script, and converting to obtain the heterogeneous aggregate stacking finite element model.

6. The method for constructing a shield tunneling model in a heterogeneous sandstone stratum according to any one of claims 1 to 5, characterized in that: The shield support mechanism model includes a shield shell model for supporting the inner wall of the tunnel, a grouting layer model located in the shield shell model, and a lining segment model located in the grouting layer model.

7. The method for constructing a shield tunneling model in a heterogeneous sandstone stratum according to any one of claims 1 to 5, characterized in that: The material property definition includes: defining the elastic modulus of aggregate; using the soil-water coupled elastoplastic model for the soil in the middle stratum, and defining the permeability coefficient and deformation characteristics of the soil; defining the elastic modulus, Poisson's ratio, yield criterion, cohesion and internal friction angle of the middle stratum; setting the shield shell model and lining segment model in the shield support mechanism model to impermeable conditions, and defining mechanical parameters; The contact condition settings include the contact settings between the middle stratum and the bottom layer, the contact settings between the middle stratum and the bearing layer, the contact settings between the soil and the aggregate in the middle stratum, the contact settings between the components in the shield support mechanism model, and the contact settings between the shield support mechanism model and the middle stratum; The setting of the interaction condition includes introducing a seepage field in the soil region of the intermediate stratum, and defining the pore pressure distribution of water and the coupling relationship between the pore pressure distribution of water and the mechanical behavior of the intermediate stratum.

8. A device for constructing a shield tunneling model in a heterogeneous sandstone stratum, characterized in that: The construction device comprises: The first construction module is used to construct a finite element model of a shield structure according to preset shield construction parameters, wherein the finite element model of the shield structure includes a stratum model and a shield support mechanism model, and along the height direction of the stratum model, the stratum model includes an intermediate stratum, a bearing layer located above the intermediate stratum, and a bottom layer located below the intermediate stratum, and the tunnel is excavated in the intermediate stratum; The second construction module is used to obtain the size data and volume of the intermediate stratum, and construct a heterogeneous aggregate accumulation finite element model based on the size data and volume of the intermediate stratum, and the sum of the volumes of all aggregates included in the heterogeneous aggregate accumulation finite element model is 30% to 40% of the volume of the intermediate stratum; The third construction module is used to first merge the finite element model of the heterogeneous aggregate accumulation with the intermediate stratum of the finite element model of the shield structure, and then define the material properties of the merged model, set contact conditions and interaction conditions, and construct a heterogeneous sand and gravel stratum shield excavation model. The intermediate stratum of the heterogeneous sand and gravel stratum shield excavation model consists of soil and aggregate.

9. A processing device, characterized in that: The processing device comprises: a processor and a memory, wherein a computer program is stored in the memory, and when the processor executes the computer program, the processing device implements the construction method according to any one of claims 1 to 7.

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