Heterogeneous sandstone stratum shield tunneling model construction method and device and processing equipment

Abstract

The invention provides a heterogeneous gravel stratum shield tunneling model construction method and device and processing equipment. The construction method comprises the steps that a finite element model of a shield structure is constructed according to preset shield construction parameters, the finite element model of the shield structure comprises a stratum model and a shield support mechanism model, and the stratum model comprises a middle stratum, a bearing layer and a bottom layer; obtaining size data and volume of an intermediate stratum, and constructing a heterogeneous aggregate accumulation finite element model based on the size data and volume of the intermediate stratum; firstly, intermediate stratums of a heterogeneous aggregate accumulation finite element model and a finite element model of a shield structure are combined, then material attributes are defined for the combined model, contact conditions and interaction conditions are set, and a heterogeneous gravel stratum shield tunneling model is constructed. According to the construction method provided by the invention, the heterogeneous stratum characteristics and the seepage influence are comprehensively considered, and the constructed shield tunneling model can be applied to complex stratum condition analysis.

Description

Technical Field

[0001] The present invention belongs to the technical field of geotechnical engineering, and in particular relates to a method, a device and a processing equipment for constructing a shield tunneling model for a heterogeneous sandstone stratum. Background Art

[0002] Shield method, mining method, open-cut construction and dark-cut construction are common means of underground tunnel construction. Among them, shield method is widely used in urban tunnel construction because of its high degree of mechanization, high construction efficiency, and green environmental protection. It can effectively reduce the impact on the surrounding environment when applied to densely built-up areas in cities, and can adjust construction parameters in real time to adapt to various geological conditions. Although shield method has many advantages, it still faces many challenges under complex formation conditions, especially when dealing with a variety of complex formations, such as soft soil, sand and gravel mixed layers, hard rock and water-rich formations. Shield construction is easily affected by seepage, water pressure and formation heterogeneity, leading to formation deformation, leakage and collapse. Therefore, the safety and stability control of shield construction has always been a research hotspot in academia and engineering.

[0003] In the current modeling research on shield construction, the soil model assumes that the strata are homogeneous or layered 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 in a heterogeneous sandstone stratum that comprehensively considers the heterogeneous stratum characteristics and seepage effects. The shield tunneling model constructed by 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 the first aspect, the present invention provides a method for constructing a shield excavation model in a heterogeneous sandstone stratum, the construction method comprising the following steps: step S10, constructing a finite element model of a shield structure according to preset shield construction parameters, the finite element model of the shield structure comprising a stratum model and a shield support mechanism model, along the height direction of the stratum model, the stratum model comprising 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, based on the intermediate stratum A finite element model of heterogeneous aggregate accumulation is constructed based on the size data and volume of the intermediate stratum, and the sum of the volumes of all aggregates contained in the finite element model of heterogeneous aggregate accumulation is 30% to 40% of the volume of the intermediate stratum; step S30, 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 of heterogeneous sand and gravel stratum, wherein the intermediate stratum of the shield tunneling model of heterogeneous sand and gravel stratum is composed of soil and aggregate.

[0006] In a specific embodiment, the bearing layer is a soft stratum, the bottom layer is a dense stratum, and the middle stratum is a sandstone stratum.

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

[0008] In a specific embodiment, the step of constructing a heterogeneous aggregate accumulation finite element model based on the size data and volume of the intermediate stratum comprises: step (1), generating a virtual space based on the size data of the intermediate stratum, wherein the virtual space has the same size data as the intermediate stratum; step (2), obtaining a geometric model of the original aggregate, taking the geometric model of the original aggregate as a basic model, generating random aggregate geometric models of different particle sizes in the virtual space 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 accumulation three-dimensional discrete element model, wherein the first aggregate accumulation 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 meets a preset condition; step (3), while keeping the central coordinates of each random aggregate geometric model unchanged, scaling down each random aggregate geometric model by a preset ratio, thereby obtaining a second aggregate accumulation three-dimensional discrete element model; and step (4), converting the second aggregate accumulation three-dimensional discrete element model into the heterogeneous aggregate accumulation finite element model by file format conversion.

[0009] In a specific embodiment, 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 multiple STL files, and each STL file also carries the position information of the random aggregate geometric model; step (b), importing the STL files in batches into MATLAB for data processing to obtain multiple IGES files; step (c), importing all IGES files into Abaqus, batch reading the IGES files through the Abaqus Python script, and converting to obtain the heterogeneous aggregate stacking finite element model.

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

[0011] In a specific implementation, 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.

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

[0013] In a second aspect, the present invention provides a device for constructing a shield tunneling model in a heterogeneous sandstone stratum, the device comprising: The first construction module is used 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 on the upper side of the intermediate stratum and a bottom layer located on the lower side of 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 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 aggregates included in the finite element model of heterogeneous aggregate accumulation 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 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 of a heterogeneous sand and gravel stratum, and the intermediate stratum of the shield tunneling model of the heterogeneous sand and gravel stratum consists of soil and aggregate.

[0014] In a third aspect, the present invention provides a processing device, comprising: 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 described above.

[0015] The beneficial effects of the present invention include at least: 1. The method for constructing a shield tunneling model in a heterogeneous sandstone stratum provided by the present invention comprises: 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 comprises a stratum model and a shield support mechanism model, wherein along the height direction of the stratum model, the stratum model comprises an intermediate stratum, a bearing layer located on the upper side of the intermediate stratum and a bottom layer located on the lower side of 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 contained in the heterogeneous aggregate accumulation finite element model is 30% to 40% of the volume of the intermediate stratum; step S30, firstly converting the heterogeneous aggregate accumulation finite element model into a finite element model; The model is merged with the middle stratum of the finite element model of the shield structure, and then the material properties of the merged model are defined, the contact conditions and the interaction conditions are set, and a shield tunneling model for a heterogeneous sand and gravel stratum is constructed, wherein the middle stratum of the shield tunneling model for a heterogeneous sand and gravel stratum is composed of soil and aggregate. The construction method of the present invention fully considers the characteristics of complex stratum particle grading, significant permeability changes, and uneven mechanical parameters. By merging the finite element model of the heterogeneous aggregate accumulation with the middle stratum of the finite element model of the shield structure, the constructed shield tunneling model for a heterogeneous sand and gravel stratum can dynamically simulate the stratum response and stability changes during shield tunneling, analyze key influencing factors such as shield propulsion force, soil pressure and seepage pressure, and provide a theoretical basis and technical support for construction parameter optimization and safety control.

[0016] Second, the present invention uses PFC software to batch generate random aggregate geometric models, and combines MATLAB tools to optimize and convert data formats to ensure Abaqus platform compatibility.

[0017] 3. The present invention establishes a mapping relationship between microstructure and macroscopic mechanical properties through finite element simulation technology, which can accurately transfer microscopic grading characteristics to macroscopic analysis, support the simulation of deformation and stress distribution of complex strata during shield advancement, and provide an accurate data basis for construction optimization and mechanical analysis.

[0018] 4. The distribution of 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 central area of ​​the tunnel is higher, while the aggregate density away from the shield excavation area gradually decreases. This distribution method can ensure that the core area of ​​the tunnel is fully filled with aggregates while reducing the amount of aggregates in the edge area, reducing the amount of calculation and improving the calculation efficiency.

[0019] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the steps of a method for constructing a shield tunneling model in a heterogeneous sandstone stratum provided by an embodiment of the present invention; Figure 2 A finite element model diagram of the shield structure constructed by the present invention; Figure 3 A diagram of a first aggregate accumulation three-dimensional discrete element model constructed by the present invention; Figure 4 A schematic diagram of the simulation of the internal structure of the shield tunneling model for the heterogeneous sandstone stratum constructed by the present invention; Figure 5 A module diagram of a device for constructing a shield tunneling model in a heterogeneous sandstone stratum provided in another embodiment of the present invention. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0022] The method for constructing a shield tunneling model for a heterogeneous sand and gravel stratum provided by the present invention is an improvement on the technical problem that the existing homogeneous strata cannot simulate complex strata, resulting in low accuracy of simulation results. The stratum is set as a three-layer structure and aggregates with different graded particle sizes are filled in the middle stratum to form a heterogeneous sand and gravel stratum. In this way, the constructed model not only takes into account the influence of complex strata on the simulation results, but also can introduce the seepage field to consider the influence of seepage and water pressure on shield construction, so that the simulation results are more accurate.

[0023] See also Figure 1 The present invention provides a method for constructing a shield tunneling model in a heterogeneous sandstone stratum, the method comprising 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 200 and a shield support mechanism model 300. Along the height direction of the stratum model 200, the stratum model 200 includes an intermediate stratum 201A, a bearing layer 202 located on the upper side of the intermediate stratum 201A, and a bottom layer 203 located on the lower side of the intermediate stratum. The tunnel is excavated in the intermediate stratum 201A.

[0024] 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.

[0025] In the present invention, the size of the shield structure is determined based on the size of the formation model, and the two are the same, that is, the length of the formation model is the length of the shield structure, the width of the formation model is the width of the shield structure, and the thickness / depth / height of the formation model is the height of the shield structure.

[0026] 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 in the shield shell model, and a lining segment model located in the grouting layer model.

[0027] Preferably, the bearing layer 202 is a soft stratum, the bottom layer 203 is a dense stratum, and the middle stratum 201A is a sandstone stratum.

[0028] Preferably, the thickness ratio of the bearing layer, the intermediate layer and the bottom layer is: (3-5): (4-6): (10-12).

[0029] In real engineering projects, the shield area often passes through multiple geological units (such as fill layers, powder layers, gravel layers, pebble layers or weathered rock layers, etc.). The present invention sets the stratum model as a three-layer structure. On the one hand, the stratum model is closer to the actual engineering construction situation and can improve the accuracy of the simulation results; on the other hand, the three-layer structure can flexibly replace any layer of soil materials to adapt to the construction simulation requirements under different site conditions. For example, if the bottom layer in a certain project is a strongly weathered rock layer or fully weathered mudstone, only the bottom layer parameters need to be changed to carry out adaptive simulation without rebuilding the overall model.

[0030] In the present invention, the finite element model of the shield structure is constructed using Abaqus software. Specifically, the entire modeling process uses a three-dimensional solid model, and a composite modeling method combining shell elements and solid elements is combined to ensure calculation accuracy and modeling efficiency.

[0031] In the present invention, the total size of the shield model structure is designed to be 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.

[0032] The stratum structure is divided into three layers, the bearing layer thickness is 7.8m, and its index parameters are: gravity is 18~20kN / m 3 , elastic modulus is 4~6MPa, cohesion is 5~15kPa, internal friction angle is 10~15 degrees; the thickness of the middle stratum is 10m, and its index parameters include: gravity is 20kN / m 3 , compression modulus is 25MPa, cohesion is 0kPa, internal friction angle is 36 degrees; the bottom layer thickness is 22.2m, and its index parameters include: gravity is 23.9kN / m 3, compression modulus is 43MPa, cohesion is 0kPa, and internal friction angle is 45 degrees.

[0033] In the present invention, the shield shell model in the shield support mechanism model is set as a shell unit 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, and the lining segment serves as the final supporting structure to provide overall stability.

[0034] Please refer to Figure 2 , Figure 2 This is a finite element model diagram of the shield structure constructed by the present invention.

[0035] Step S20: Obtain the size data and volume of the intermediate stratum, and construct a heterogeneous aggregate stacking 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 stacking finite element model is 30% to 40% of the volume of the intermediate stratum.

[0036] In an optional 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): generating a virtual space based on the dimension data of the intermediate stratum, wherein the virtual space has the same dimension data as that of the intermediate stratum.

[0037] In the present invention, the size of the intermediate layer is 80m (length) × 50m (width) × 10m (height), so the size of the virtual space is also 80m (length) × 50m (width) × 10m (height).

[0038] 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.

[0039] It should be noted that, in the present invention, the particle size of aggregate refers to the equivalent particle size of aggregate.

[0040] In the present invention, the PFC3D software is used to construct a first aggregate accumulation three-dimensional discrete element model.

[0041] In an optional implementation, a geometric model of the original aggregate is constructed based on the selected real aggregate.

[0042] This step specifically includes: randomly selecting real aggregates, and obtaining a geometric model of the real aggregates by an imaging method or a three-dimensional scanning method.

[0043] It should be noted that, in the present invention, the imaging method or the three-dimensional scanning method both adopt the existing technology.

[0044] In an optional implementation, the random function is: .

[0045] in, is the i-th aggregate size generated; The minimum particle size is set to 1. The maximum particle size is set to 5. A random number between 0 and 1.

[0046] The random function is used to determine the particle size of each level of aggregate, which can ensure that the random distribution of particle size meets the heterogeneous characteristics.

[0047] In the present invention, taking the geometric model of the original aggregate as the basic model can be understood as: the shape of the subsequently generated random aggregate geometric model of different particle sizes is similar to the shape of the geometric model of the original aggregate, that is, the random aggregate geometric model is obtained by enlarging or reducing the geometric model of the original aggregate, and the magnification or reduction multiple = particle size calculated by the random function / equivalent particle size of the original aggregate.

[0048] In an optional embodiment, the multi-graded aggregate model set includes an extra-large particle size aggregate model set with an equivalent particle size range of 3.8m~5m, a large particle size aggregate model set with an equivalent particle size range of 2.8m~3.8m, a medium particle size aggregate model set with an equivalent particle size range of 1.8m~2.8m and a small particle size aggregate model set with an equivalent particle size range of 1m~1.8m.

[0049] In the present invention, according to the engineering requirements, the aggregates are divided into different gradation ranges. Due to the huge amount of actual engineering materials and the complex composition, the more BBS the better the number of aggregates, and too much will cause the computer to fail to meet the requirements. Compared with the overall size of the model, if the aggregate is too small, the advantage of heterogeneity 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 size meets the engineering requirements and reduce the calculation complexity.

[0050] In an optional embodiment, the volume fraction of each graded aggregate model set meets the preset conditions, which means that, taking the sum of the volumes of all aggregates in the first aggregate stacking three-dimensional discrete element model 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%.

[0051] In one embodiment of the present invention, the volume fraction of each graded aggregate model set meets the preset conditions, which means that the sum of the volumes of all aggregates in the extra-large particle size aggregate model set is 28.1% of the total volume, the sum of the volumes of all aggregates in the large particle size aggregate model set is 25.1% of the total volume, the sum of the volumes of all aggregates in the medium particle size aggregate model set is 28.6% of the total volume, and the sum of the volumes of all aggregates in the small particle size aggregate model set is 18.2% of the total volume, wherein the total volume is the sum of the volumes of all aggregates in the first aggregate stacking three-dimensional discrete element model.

[0052] In other embodiments, the volume fractions of different levels of 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.

[0053] In an optional embodiment, the sum of the volumes of all aggregates included in the heterogeneous aggregate accumulation finite element model is 40% of the volume of the middle stratum.

[0054] For ease of understanding, an example is given based on the optional data above. Assume that the volume of the middle stratum is 80m×50m×10m=4000m 3 , then the volume of all aggregates included in the finite element model of heterogeneous aggregate accumulation = 4000 × 40% = 1600m 3 , then the sum of the volumes of all aggregates in the extra-large particle size aggregate model set = 1600×28.1%, the sum of the volumes of all aggregates in the large particle size aggregate model set = 1600×25.1%, the sum of the volumes of all aggregates in the medium particle size aggregate model set = 1600×28.6%, and the sum of the volumes of all aggregates in the small particle size aggregate model set = 1600×18.2%.

[0055] In another optional embodiment, the volume fraction of each graded aggregate model set that meets the preset conditions may 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 limited respectively.

[0056] For ease of understanding, an example is given. If the volume of the virtual space is 100%, and it is assumed that the sum of the volumes of all aggregates contained in the heterogeneous aggregate accumulation finite element model is 40% of the volume of the intermediate stratum, 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%.

[0057] Please refer to Figure 3 , Figure 3 This is a diagram of the first aggregate stacking three-dimensional discrete element model constructed in the present invention.

[0058] 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.

[0059] In the present invention, the scaling down operation corresponding to this step is performed in the PFC3D software.

[0060] In the PFC3D calculation process, in order to reduce the calculation error and ensure the stability of the aggregate stacking structure, the volume of all random aggregates is uniformly fine-tuned to reduce the calculation error, while keeping the center coordinates of each random aggregate geometric model unchanged to ensure the integrity of the aggregate structure. The adjustment formula is as follows: .

[0061] in, No. i The adjusted volume of random aggregate, V i For the i The initial volume of random aggregate, δ The zoom ratio is set.

[0062] In the present invention, δ=0.001 to minimize the error of the volume fraction.

[0063] In the present invention, the center coordinates of the random aggregate remain unchanged after adjustment, and only the volume is fine-tuned to avoid boundary problems caused by precision errors. This adjustment method is applicable to all random aggregates, rather than just random aggregates at the boundary of the computational domain, to ensure that all random aggregates can still be correctly identified after being imported into Abaqus and are consistent with the calculation results in PFC3D.

[0064] Step (4): converting the second aggregate stacking three-dimensional discrete element model into the heterogeneous aggregate stacking finite element model through file format conversion.

[0065] In an optional embodiment, the step (4) includes: Step (a), exporting the second aggregate stacking three-dimensional discrete element model as a plurality of STL files, and each STL file also carries the position information of the random aggregate geometric model.

[0066] It is understood that each random aggregate geometry model is saved separately as an STL file.

[0067] The position and volume distribution of random aggregates have been set during PFC3D calculation and stored as database information. Therefore, when constructing the finite element model of heterogeneous aggregate accumulation, these coordinate data can be directly called without the need for placement operations.

[0068] Step (b), batch importing the STL files into MATLAB for data processing to obtain multiple IGES files.

[0069] 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.

[0070] The file format conversion method provided by the present invention can ensure that the random aggregate geometric model can be correctly imported and is consistent with the PFC3D calculation result.

[0071] 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 the contact conditions and interaction conditions, and construct a heterogeneous sand and gravel stratum shield tunneling model. The intermediate stratum 201B of the heterogeneous sand and gravel stratum shield tunneling model is composed of soil and aggregate.

[0072] In the present invention, the step S30 is performed using Abaqus software.

[0073] In an optional embodiment, the operation of merging the intermediate stratum of the finite element model of the heterogeneous aggregate accumulation and the finite element model of the shield structure is specifically as follows: the finite element model of the heterogeneous aggregate accumulation and the intermediate stratum of the finite element model of the shield structure are merged by Boolean operation, and the soil body where the intermediate stratum overlaps with the aggregate is disabled.

[0074] In an optional embodiment, the definition of material properties includes: defining the elastic modulus of aggregate; using a water-soil coupled elastoplastic model for the soil in the intermediate stratum, and defining the permeability and deformation characteristics of the soil; defining the elastic modulus, Poisson's ratio, yield criterion, cohesion and internal friction angle of the intermediate stratum; setting the shield shell model and lining segment model in the shield support mechanism model to impermeable conditions, and defining mechanical parameters, wherein the mechanical parameters include elastic modulus and density.

[0075] In the present invention, the elastic modulus of the aggregate is between 10000MPa and 30000MPa, which is a high-rigidity elastic parameter.

[0076] In an optional embodiment, 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 of the middle stratum and the aggregate, the contact settings between the elements in the shield support mechanism model, and the contact settings between the shield support mechanism model and the middle stratum.

[0077] In an optional embodiment, 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.

[0078] In the present invention, seepage refers to the flow of fluid in porous media.

[0079] In the present invention, the mechanical behavior of the intermediate formation includes deformation, destruction and stability.

[0080] Please refer to Figure 4 , Figure 4 A simulation schematic diagram of the internal structure of a shield tunneling model in a heterogeneous sandstone stratum constructed in the present invention.

[0081] The shield tunneling model in the heterogeneous sand and gravel stratum constructed by the present invention is divided into grids for simulation model, and boundary conditions and loading processes are applied, including the effects of shield thrust, soil pressure and seepage pressure, etc., and calculation and analysis are performed. The stratum deformation and force response results can be output for analyzing the stability and safety of the shield construction process.

[0082] See also Figure 5The present invention also provides a device 100 for constructing a shield tunneling model in a heterogeneous sandstone stratum, the device 100 comprising: The first construction module 101 is used 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. The tunnel is excavated in the intermediate stratum.

[0083] The second construction module 102 is used 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 aggregates included in the finite element model of heterogeneous aggregate accumulation is 30% to 40% of the volume of the intermediate stratum.

[0084] The third construction module 103 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 material properties, set contact conditions and interaction conditions for the merged model to 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.

[0085] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the working process of constructing the device described above can refer to the contents in the aforementioned method embodiment and will not be repeated here.

[0086] The present invention also provides a processing device, Figure 5 The construction device shown can be arranged in the processing device. The processing device includes a memory, a processor, a communication interface and a bus. The memory, the processor and the communication interface are connected to each other through the bus. In addition, the computer device may include multiple processors so that the functions of the above-mentioned different modules can be realized by different processors.

[0087] The memory may be a read-only memory, a static storage device, a dynamic storage device or a random access memory. The memory may store an executable code sequence. 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 in a heterogeneous sandstone formation provided in the embodiment of the present application. The memory may also include software modules and data required for other running processes such as an operating system. The operating system may be LINUX, UNIX, WINDOWSTM, etc.

[0088] 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.

[0089] 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 method for constructing a shield tunneling model for a heterogeneous sandstone stratum of the present application may be completed by hardware integrated logic circuits or software instructions in the processor. The above-mentioned processor may also be a general-purpose processor, digital signal processing (DSP), application-specific integrated circuit (ASIC), field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application may be implemented or executed. 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 the embodiments of the present application may be directly embodied as being executed by a hardware decoding processor, or may be executed by a combination of hardware and software modules in a 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. The storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the method for constructing a shield tunneling model for a heterogeneous sandstone stratum according to the embodiment of the present application.

[0090] The communication interface uses a transceiver module such as, but not limited to, a transceiver to realize the communication between the computer device and other devices or the communication network. For example, the communication interface can 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.

[0091] A bus may include a pathway that transfers information between various components of a computer device (eg, memory, processor, communication interface).

[0092] 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 method for constructing a shield tunneling model in a heterogeneous sandstone formation provided in an embodiment of the present application. Any computer device can be a computer device in a cloud data center (e.g., a server), or a computer device in an edge data center, etc.

[0093] The descriptions of the processes corresponding to the above-mentioned figures have different emphases. For parts that are not described in detail in a certain process, please refer to the relevant descriptions of other processes.

[0094] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product 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 process or function of the method for constructing a shield tunneling model for a heterogeneous sandstone formation provided in the embodiment of the present application is implemented in whole or in part.

[0095] The processing device may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. Computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium stores computer program instructions for providing data synchronization cloud services.

[0096] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which 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: (3-5): (4-6): (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 claim 4 or 5, characterized in that: The multi-graded aggregate model set includes an extra-large aggregate model set with an equivalent particle size range of 3.8m~5m, a large aggregate model set with an equivalent particle size range of 2.8m~3.8m, a medium aggregate model set with an equivalent particle size range of 1.8m~2.8m, and a small aggregate model set with an equivalent particle size range of 1.0m~1.8m.

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 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.

8. 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.

9. 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.

10. 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 8.

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