Shield tail synchronous grouting simulation method and system for soft soil stratum shield construction

Abstract

The invention discloses a soft soil stratum shield construction shield tail synchronous grouting simulation method and system, and relates to the technical field of tunnel and underground engineering, and the method comprises the following steps: constructing a shield tail synchronous grouting three-dimensional finite element model, and establishing geometric components of the three-dimensional finite element model; physical parameters, material attributes and state equations of the geometric components are obtained; selecting an explicit time integration method and setting a time analysis step and a time increment step; appointing a grid unit type, and performing grid division; setting contact attributes, boundary conditions of geometric components and a predefined field; and area initialization is carried out, and fluid-solid coupling calculation is carried out after initialization. According to the invention, the filling diffusion process of slurry in the shield tail gap and the interaction of lining-slurry-soil body are realized, the conformity is high, the cost is low, and different engineering geological conditions can be simulated; the influence of grouting construction parameters on the grouting effect is researched by adjusting the grouting pressure, the grouting speed, the grouting rate, the slurry viscosity, the density and other parameters, and guidance is provided for engineering.

Description

Technical Field

[0001] The invention relates to the technical field of tunnels and underground engineering, and more particularly to a method and system for simulating synchronous grouting of a shield tail in shield construction in soft soil. Background Art

[0002] The shield method is widely used in underground construction due to its advantages such as fast construction speed and little impact on surrounding strata and structures. During the shield tunneling process, due to the diameter difference between the cutterhead and the lining, an annular space is formed between the surrounding soil and the tunnel lining after the shield tunneling. This annular space is usually called the shield tail gap. The shield tail gap is an important factor affecting the stability of the surrounding strata and structures. In shield tunnel construction, the synchronous grouting method is generally used to fill the shield tail gap around the lining to reduce the deformation of the soil after the shield tail is removed. The traditional finite element simulation method applies pressure to the soil around the tunnel to study the impact of the shield grouting construction process on the surrounding strata, but it cannot study the diffusion mechanism of the slurry in the shield tail gap.

[0003] Therefore, how to provide a simulation method and system for synchronous grouting at the shield tail of shield construction in soft soil strata, simulate the diffusion mechanism of slurry in the shield tail gap in soft soil strata, and provide guidance for synchronous grouting construction parameters is an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0004] In view of this, the present invention provides a method and system for simulating synchronous grouting of shield tail in shield construction in soft soil strata. The diffusion of slurry in the gap of shield tail and the interaction of "lining-slurry-soil" are simulated based on the finite element model coupled with Euler-Lagrangian. Compared with the penetration diffusion of discrete elements, the finite element simulation is more about filling diffusion, which is more in line with the synchronous grouting process of soft soil layers in reality, and at the same time greatly reduces the calculation cost. In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A method for simulating synchronous grouting of shield tail in shield construction in soft soil, comprising:

[0006] Construct a three-dimensional finite element model of synchronous grouting of the shield tail and establish the geometric components of the three-dimensional finite element model;

[0007] Get the physical parameters of the geometric components and set the material properties and state equations for the geometric components;

[0008] Select the explicit time integration method and set the time analysis step and time increment step;

[0009] Specify the mesh element type and mesh the three-dimensional finite element model of synchronous grouting at the shield tail;

[0010] Set contact properties, boundary conditions and predefined fields for geometric components;

[0011] The regional initialization is performed, and after the initialization, the fluid-solid coupling calculation of the three-dimensional finite element model is performed to obtain the simulation results of the synchronous grouting of the shield tail and analyze them.

[0012] Optionally, the geometric components include Euler components and Lagrangian components, the Euler components are the grouting pipe and the grouting area, and the Lagrangian components are the soil, the lining continuum and the injected slurry.

[0013] Optionally, the state equation is a linear US-UP Hugoniot form of the Mie-Grüneisen state equation for state equation modeling of the slurry, and the linear US-UP state equation model is used to simulate the incompressible flow controlled by the Navier-Stokes motion equations.

[0014] Optionally, the obtaining of physical parameters of the geometric component and setting material properties for the geometric component includes:

[0015] The soil was subjected to particle grading measurement and triaxial compression test to obtain soil physical parameters, and the material properties were assigned to the soil in the three-dimensional finite element model of synchronous grouting at the shield tail.

[0016] Conducting performance tests on the synchronous grouting slurry to obtain the slurry physical parameters;

[0017] Rheological tests were carried out on the synchronous grouting slurry to obtain the rheological parameters of the slurry, and the rheological curve was established. The rheological curve was fitted to obtain the rheological model of the slurry, and the material properties were given to the slurry in the three-dimensional finite element model of synchronous grouting at the shield tail.

[0018] Optionally, the specified grid unit type includes: setting the soil, lining continuum and injected slurry as Lagrangian grid components, setting the grouting pipe and grouting area as Eulerian grid components, the Lagrangian component adopts 8-node C3D8R unit, and the Eulerian component adopts 8-node EC3D8R unit.

[0019] Optionally, meshing the shield tail synchronous grouting three-dimensional finite element model includes:

[0020] The mesh near the grouting area of ​​the Lagrangian component is encrypted, and the sparse mesh is used in the area outside the encrypted area. The mesh of the Euler component is encrypted. After the mesh division is completed, the mesh properties are adjusted and all are changed to explicit meshes;

[0021] The flow of slurry in the Euler grid is tracked by calculating the Euler volume fraction EVF of the slurry in each unit. If the slurry completely fills the Euler unit, the EVF is 1; if there is no slurry in the Euler unit, the EVF is 0; if the EVF of the slurry in a certain Euler unit is greater than 0 and less than 1, the rest of the unit will be automatically set to an empty area;

[0022] The fluid volume fraction method is used to track the geometric boundary of the injected slurry. The geometric boundary of the slurry is determined based on the EVF of the slurry and the empty area within the Eulerian unit. In each unit, the interface between the slurry and the empty area is determined by a straight line.

[0023] Optionally, the setting of contact attributes includes: adopting a penalty function contact method, wherein the normal contact adopts hard contact;

[0024] The outer radius of the Euler region is slightly larger than the outer diameter of the gap ring at the shield tail, allowing the grout to penetrate into the Lagrangian region in a small area. The grout is allowed to deform temporarily in the Lagrangian region, allowing the soil to pass through the Euler domain without resistance until it encounters an Euler unit with a non-zero EVF;

[0025] In the penalty function contact method, the velocity of the soil boundary generates a kinetic force on the grout region, while the grout generates a pressure on the soil region.

[0026] Optionally, the boundary conditions of the geometric component include:

[0027] In the initial analysis step, no changes in the flow velocity boundary conditions are set;

[0028] In the dynamic display analysis step, change the flow velocity in the horizontal direction;

[0029] The boundary condition of the Euler component is to set the velocity boundary of the Euler component in the x, y, and z directions to 0, that is, to fully constrain the velocity;

[0030] In the subsequent dynamic display analysis step, the horizontal flow velocity is adjusted.

[0031] Optionally, the predefined field includes: setting an initial slurry area at the grouting hole position, changing void to 0 after selecting the area to achieve full filling, and initializing the Euler area to an empty area without any material properties.

[0032] Optionally, a shield tail synchronous grouting simulation system for shield construction in soft soil strata includes:

[0033] Construction module: used to construct the three-dimensional finite element model of the synchronous grouting of the shield tail and establish the geometric components of the three-dimensional finite element model;

[0034] Fitting module: used to obtain the physical parameters of geometric components and set material properties and state equations for geometric components;

[0035] Method selection module: used to select explicit time integration method and set time analysis step and time increment step;

[0036] Meshing module: used to specify the mesh unit type and mesh the three-dimensional finite element model of synchronous grouting at the shield tail;

[0037] Setting module: used to set contact properties, boundary conditions of geometric components and predefined fields;

[0038] Simulation analysis module: used for regional initialization, after which the fluid-solid coupling calculation of the three-dimensional finite element model is performed to obtain the shield tail synchronous grouting simulation results and perform analysis.

[0039] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a method and system for simulating synchronous grouting of the shield tail in shield construction in soft soil, which has the following beneficial effects:

[0040] The invention proposes a simulation method for synchronous grouting of the tail of a shield in soft soil layer shield construction, comprising: constructing a three-dimensional finite element model of synchronous grouting of the tail of a shield, and establishing geometric components of the three-dimensional finite element model; obtaining physical parameters of the geometric components, and setting material properties and state equations for the geometric components; selecting an explicit time integration method and setting a time analysis step and a time increment step; specifying a grid unit type, and gridding the three-dimensional finite element model of synchronous grouting of the tail of a shield; setting contact properties, boundary conditions of geometric components and predefined fields; performing regional initialization, and after initialization, performing fluid-solid coupling calculation of the three-dimensional finite element model, obtaining a simulation result of synchronous grouting of the tail of a shield and performing analysis. Compared with traditional finite element simulation, the present invention can realize the filling and diffusion process of slurry in the gap at the shield tail and the interaction of "lining-slurry-soil"; compared with discrete element simulation, it is more in line with the synchronous grouting process of soft soil layers in reality, and the calculation cost is greatly reduced; different engineering geological conditions can be simulated by adjusting the density, elastic modulus, Poisson's ratio, internal friction angle, internal cohesion and tunnel burial depth; by adjusting the settings of parameters such as grouting pressure, grouting speed, grouting rate, slurry viscosity and density, the influence of grouting construction parameters on the grouting effect can be studied to provide guidance for the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0042] Figure 1A schematic flow chart of a method for simulating synchronous grouting at the tail of a shield in soft soil shield construction provided by the present invention.

[0043] Figure 2 A half view of the geometric model of the Lagrangian component provided by the present invention.

[0044] Figure 3 This is a schematic diagram of the geometric model of the Euler component provided by the present invention.

[0045] Figure 4 This is a schematic diagram of the change process of the slurry volume fraction cloud diagram every 2s during the simulated synchronous grouting provided by the present invention.

[0046] Figure 5 A schematic diagram of surface settlement verification for simulation and experiment provided by the present invention.

[0047] Figure 6 A schematic diagram of the grouting pressure verification for the simulation and test provided by the present invention. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The embodiment of the present invention discloses a method for simulating synchronous grouting of shield tail in shield construction in soft soil. Figure 1 As shown, including:

[0050] Construct a three-dimensional finite element model of synchronous grouting of the shield tail and establish the geometric components of the three-dimensional finite element model;

[0051] Get the physical parameters of the geometric components and set the material properties and state equations for the geometric components;

[0052] Select the explicit time integration method and set the time analysis step and time increment step;

[0053] Specify the mesh element type and mesh the three-dimensional finite element model of synchronous grouting at the shield tail;

[0054] Set contact properties, boundary conditions and predefined fields for geometric components;

[0055] The regional initialization is performed, and after the initialization, the fluid-solid coupling calculation of the three-dimensional finite element model is performed to obtain the simulation results of the synchronous grouting of the shield tail and analyze them.

[0056] Furthermore, a three-dimensional finite element model of synchronous grouting of the shield tail is established using modeling software, and the geometric model dimensions of the soil, lining continuum, injected slurry, grouting pipe and grouting area are set. The geometric components include Euler components and Lagrangian components. The Euler components are the grouting pipe and the grouting area, and the Lagrangian components are the soil, lining continuum and injected slurry.

[0057] Furthermore, in the Lagrangian component, the soil adopts the linear elastic + Mohr Coulomb constitutive model, and the basic parameters include internal friction angle, cohesion, elastic modulus and Poisson's ratio. The lining and the injected slurry adopt the elastic-plastic constitutive model, which can describe the stress-strain relationship of the material in the elastic and plastic stages. The specific physical parameters are obtained according to the test.

[0058] In the Euler component, the slurry is modeled using the linear US-UP Hugoniot form of the Mie-Grüneisen state equation. The linear US-UP state equation model can be used to simulate incompressible flow governed by the Navier-Stokes equations of motion. The Mie-Grüneisen state equation is in the following form:

[0059] pp H =Γρ(E m -E H );

[0060]

[0061]

[0062]

[0063]

[0064] U S =c0+sU P ;

[0065] Where Γ is the Mie-Grüneisen parameter, c0 is the speed of sound, s is an empirical parameter in shock wave propagation, ρ is the material density; p is the pressure defined as positive in compression; p H Hugoniot pressure; E m is the internal energy per unit mass; E H is the Hugoniot specific energy per unit mass; ρ0 is the reference density; Γ0 is the material constant; η (η=1-ρ0 / ρ) is the nominal volume compressive strain, c0 and s establish the particle velocity (U S ) and linear shock wave velocity (U P ) between them.

[0066] Furthermore, the obtaining of physical parameters of the geometric components and setting material properties for the geometric components includes:

[0067] The soil is subjected to particle grading measurement and triaxial compression test to obtain soil physical parameters such as density, elastic modulus, Poisson's ratio, internal friction angle, internal cohesion and particle grading curve, and the material properties of the soil are assigned in the three-dimensional finite element model of synchronous grouting at the shield tail;

[0068] Conducting performance tests on synchronous grouting slurry to obtain slurry physical parameters such as density, viscosity and dynamic viscosity;

[0069] Rheological tests were carried out on the synchronous grouting slurry to obtain the rheological parameters of the slurry, and the rheological curve was established. The rheological curve was fitted to obtain the rheological model of the slurry, and the material properties were given to the slurry in the three-dimensional finite element model of synchronous grouting at the shield tail.

[0070] Furthermore, selecting an explicit time integration method and setting a time analysis step and a time increment step includes: based on a calculation method under explicit dynamics, using an explicit time integration method, directly discretizing dynamic equations, setting a time analysis step, setting the time increment step to automatic, and solving a group of nonlinear differential equations using a central difference method.

[0071] Furthermore, the specified grid unit type includes: setting the soil, lining continuum and injected slurry as Lagrangian grid components, setting the grouting pipe and grouting area as Eulerian grid components, the Lagrangian component adopts the 8-node C3D8R unit, and the Eulerian component adopts the 8-node EC3D8R unit.

[0072] Furthermore, the meshing of the shield tail synchronous grouting three-dimensional finite element model includes:

[0073] The mesh near the grouting area of ​​the Lagrangian component is encrypted, and the sparse mesh is used in the area outside the encrypted area. The mesh of the Euler component is encrypted. After the mesh division is completed, the mesh properties are adjusted and all are changed to explicit meshes;

[0074] The flow of slurry in the Euler grid is tracked by calculating the Euler volume fraction EVF of the slurry in each unit. If the slurry completely fills the Euler unit, the EVF is 1; if there is no slurry in the Euler unit, the EVF is 0; if the EVF of the slurry in a certain Euler unit is greater than 0 and less than 1, the rest of the unit will be automatically set to an empty area;

[0075] The fluid volume fraction method is used to track the geometric boundary of the injected slurry. The geometric boundary of the slurry is determined based on the EVF of the slurry and the empty area within the Eulerian unit. In each unit, the interface between the slurry and the empty area is determined by a straight line.

[0076] Furthermore, the setting of contact properties includes: adopting a penalty function contact method, wherein the normal contact adopts hard contact;

[0077] Contact between Eulerian and Lagrangian elements is not required;

[0078] The outer radius of the Euler region is slightly larger than the outer diameter of the gap ring at the shield tail, allowing the grout to penetrate into the Lagrangian region in a small area. The grout is allowed to deform temporarily in the Lagrangian region, allowing the soil to pass through the Euler domain without resistance until it encounters an Euler unit with a non-zero EVF;

[0079] In the penalty function contact method, the velocity of the soil boundary generates a kinetic force on the grout region, while the grout generates a pressure on the soil region.

[0080] Furthermore, the boundary conditions of the geometric components include:

[0081] In the initial analysis step, no changes in the flow velocity boundary conditions are set;

[0082] In the dynamic display analysis step, change the flow velocity in the horizontal direction;

[0083] The boundary condition of the Euler component is to set the velocity boundary of the Euler component in the x, y, and z directions to 0, that is, to fully constrain the velocity;

[0084] In the subsequent dynamic display analysis step, the horizontal flow velocity is adjusted.

[0085] Furthermore, the predefined field includes: setting an initial slurry area at the grouting hole position, that is, the slurry at the 4 grouting hole positions, changing void to 0 after selecting the area to achieve full filling, and initializing the Euler area to an empty area without any material properties.

[0086] Furthermore, in the Euler formula, the conservation equations are written in the form of spatial derivatives, and the material can flow freely in a discrete grid fixed in space. In the Lagrangian formula, the material derivative form is used, and the material can deform with the grid.

[0087] The Lagrangian form of the conservation equations for mass, momentum, and energy is as follows:

[0088]

[0089]

[0090]

[0091] Where t is time, ρ is material density; v is material velocity; σ is Cauchy stress; b is body force; e is internal energy per unit volume; is the strain rate.

[0092] The conservation equations for mass, momentum, and energy in Euler form are as follows:

[0093]

[0094]

[0095]

[0096] in, is the tensor product, ρ is the material density; v is the material velocity; σ is the Cauchy stress; b is the body force; e is the internal energy per unit volume; is the strain rate.

[0097] In a specific embodiment, a shield tail synchronous grouting simulation system for shield construction in soft soil strata includes:

[0098] Construction module: used to construct the three-dimensional finite element model of the synchronous grouting of the shield tail and establish the geometric components of the three-dimensional finite element model;

[0099] Fitting module: used to obtain the physical parameters of geometric components and set material properties and state equations for geometric components;

[0100] Method selection module: used to select explicit time integration method and set time analysis step and time increment step;

[0101] Meshing module: used to specify the mesh unit type and mesh the three-dimensional finite element model of synchronous grouting at the shield tail;

[0102] Setting module: used to set contact properties, boundary conditions of geometric components and predefined fields;

[0103] Simulation analysis module: used for regional initialization, after which the fluid-solid coupling calculation of the three-dimensional finite element model is performed to obtain the shield tail synchronous grouting simulation results and perform analysis.

[0104] Furthermore, the simulation calculation results are extracted to analyze the slurry pressure, surface settlement, vertical displacement of the soil around the tunnel, and soil pressure.

[0105] In a specific implementation, a method for simulating synchronous grouting of the shield tail in shield construction in soft soil strata is provided, and the specific steps are as follows:

[0106] The numerical simulation was carried out with the synchronous grouting of the shield tail in soft soil as the research target. The geometric dimensions of the scaled model test of the four-hole synchronous grouting of the shield tail in soft soil were referred to, and the three-dimensional finite element model of synchronous grouting of the shield tail was established using the modeling software. The range of the studied soil, the buried depth of the tunnel, the lining continuum, the injected slurry and the grouting pipe were defined by setting the size parameters of the geometric model.

[0107] In the reference scale model test, the dimensions of the model box are 1.2m (length) × 1.2m (width) × 1.2m (height), the inner and outer diameters of the lining are 0.35m and 0.37m respectively, and the inner and outer diameters of the model shield machine are 0.37m and 0.40m respectively.

[0108] In a specific embodiment, Figure 2 The Lagrangian component of the simulation model is a half view. Considering that the best detection surface selected in the test is the center of the tunnel, the area without slurry injection, that is, the shield tail gap (grouting area), is hollowed out and spliced ​​with the Euler component at the corresponding tunnel center position to realize the slurry inflow process. Based on the specific size of the scaled test and considering the grouting process of the middle section, the soil range is 0.7m (length) × 1.2m (width) × 1.2m (height); the inner diameter of the lining is 0.35m, the outer diameter is 0.37m, and the length is 0.7m; the inner diameter of the slurry injected area is 0.37m, the outer diameter is 0.4m, and the length is 0.6m. The shield tail gap is filled, simulating the situation of 100% grouting rate; the inner diameter of the gap area is 0.37m, the outer diameter is 0.4m, and the length is 0.1m.

[0109] In a specific embodiment, Figure 3 For the Euler component view of the simulation model, a grouting hole is set at the upper and lower positions with an angle of 45°, and the diameter of the grouting hole is 0.01m to simulate the 4-hole grouting process in actual working conditions. At the same time, the Euler boundary and inflow velocity are set at the grouting port to achieve the continuous injection process of slurry at the grouting port. The Euler component is 0.1m long, with an inner diameter of 0.37m and an outer diameter of 0.43m.

[0110] In a specific embodiment, in the Lagrangian component, the soil constitutive model adopts linear elasticity + Mohr-Coulomb, and the basic parameters include internal friction angle, cohesion, elastic modulus and Poisson's ratio, etc. The lining and the injected slurry adopt elastoplastic constitutive model. This model can describe the stress-strain relationship of the material in the elastic stage and the plastic stage. The specific physical parameters are obtained according to the test.

[0111] In a specific embodiment, in an Euler component, a hydrodynamic material model is used to define the behavior of the fluid to simulate the slurry flow phenomenon, wherein the volume strength of the slurry is described by a state equation (EOS), and the EOS is used to describe the behavior of the slurry under high strain rate and large deformation conditions. The slurry model adopts the linear US-UP Hugoniot form of the Mie-Grüneisen state equation, and the linear US-UP state equation model is used to simulate the incompressible flow controlled by the Navier-Stokes motion equation. The Mie-Grüneisen state equation is in the form of:

[0112] pp H =Γρ(Em -E H );

[0113]

[0114]

[0115]

[0116]

[0117] U S =c0+sU P ;

[0118] Where ρ is the material density, p is the pressure which is defined as positive when compressed, and p H stands for Hugoniot pressure, E m Represents the internal energy per unit mass, E H represents the Hugoniot specific energy per unit mass, ρ0 is the reference density, Γ0 is the material constant, η (η=1-ρ0 / ρ) is the nominal volume compressive strain, c0 and s establish the particle velocity (U S ) and linear shock wave velocity (U P ) between them.

[0119] In a specific embodiment, it is necessary to conduct field sampling of the soft soil layer to be simulated to obtain sufficient original soil samples. By conducting a triaxial compression test on the original soil sample, the stress-strain relationship curve, Mohr stress circle, and strength envelope of the original soil sample are obtained. Then, the specific physical parameters of the original soil sample are obtained. The soil density is 1780kg / m 3 , elastic modulus is 10.5MPa, Poisson’s ratio is 0.3, internal friction angle is 20.38°, internal cohesion is 53.2kPa, and material properties are assigned to soil components in the numerical model.

[0120] The required simulated synchronous grouting slurry was prepared. The performance of the synchronous grouting slurry was tested to obtain specific slurry physical parameters. The slurry density was 1200kg / m 3 The dynamic viscosity is 0.105Pa·s. The rheological parameters of the slurry are obtained through the rheological test of the synchronous grouting slurry, and the rheological curve is established and fitted. Considering that the slurry is a Newtonian fluid, the material properties are given to the slurry in the model.

[0121] In a specific embodiment, based on the calculation method under the display dynamics, an explicit time integration method is adopted to directly discretize the dynamic equations, the time analysis step is set to 12s, and the time increment step is set to automatic. The central difference method is used to solve the nonlinear differential equations.

[0122] In a specific embodiment, the soil component, the slurry injected component and the lining continuum component are Lagrangian mesh components, and the grouting area component is an Euler mesh component. The Lagrangian component uses 8-node C3D8R, the number of elements is 35104, and the number of nodes is 39168; the Euler component uses 8-node EC3D8R, the number of grids is 31232, and the number of nodes is 38208.

[0123] In a specific embodiment, the geometric model of synchronous grouting of the shield tail is meshed, specifically: the mesh near the grouting area of ​​the Lagrangian component is encrypted, the area outside the encryption process uses a sparse mesh, and the mesh of the Euler component is encrypted. After the meshing is completed, the mesh properties are adjusted and all are changed to explicit meshes. Focus on the interaction between the "lining-grouting-soil" in the shield tail gap;

[0124] The flow of slurry in the Euler grid is tracked by calculating the Euler volume fraction (EVF) of the slurry in each cell. If the slurry completely fills the Euler cell, the EVF is 1; if there is no slurry in the Euler cell, the EVF is 0. If the EVF of the slurry in a certain Euler cell is greater than 0 and less than 1, the rest of the cell will be automatically set to an empty area;

[0125] The fluid volume fraction method is used to track the geometric boundary of the injected slurry. The geometric boundary of the slurry is determined based on the EVF of the slurry and the empty area within the Eulerian unit. In each unit, the interface between the slurry and the empty area is determined by a straight line.

[0126] In a specific embodiment, the contact properties are set and a "penalty function" contact method is adopted, in which hard contact is adopted for normal contact. Contact between the Euler unit and the Lagrangian unit is not required. The outer radius of the Euler region is slightly larger than the outer diameter of the shield tail gap ring, allowing the slurry to penetrate into the Lagrangian region in a small range, and the slurry can be temporarily deformed in the Lagrangian region. At the same time, the soil can pass through the Euler domain without resistance until it encounters an Euler unit with a non-zero EVF. In the "penalty function" contact method, the velocity of the soil boundary produces a kinetic force on the slurry region, and the pressure in the slurry produces a force on the soil region.

[0127] In a specific embodiment, boundary conditions are set for the geometric model. In the initial analysis step, no change in the flow velocity boundary conditions is set. In the dynamic display analysis step, the flow velocity in the horizontal direction is changed. The boundary conditions of the Euler component set the velocity boundary to 0 in the x, y, and z directions of the Euler component, that is, the velocity is fully constrained. This setting can ensure that during the simulation process, stable flow velocity boundary conditions are maintained in the initial stage, and in the subsequent dynamic display analysis step, the flow velocity in the horizontal direction can be adjusted. By constraining the velocity of the Euler component in all directions, its motion state in the simulation can be better controlled, which helps to improve the accuracy and stability of the simulation. The predefined field sets the initial slurry area, that is, the slurry at the positions of the four grouting holes. After selecting the area, change void to 0 to achieve full filling. The Euler domain is initialized as an empty area without any material properties.

[0128] In a specific embodiment, the conservation equations in the Euler formula are written in the form of spatial derivatives, and the material can flow freely in a discrete grid fixed in space, while the Lagrangian formula uses the material derivative form, and the material can deform with the grid.

[0129] The conservation equations for mass, momentum, and energy can be written in Lagrangian form as follows:

[0130]

[0131]

[0132]

[0133] Where ρ is the material density; v is the material velocity; σ is the Cauchy stress; b is the body force; e is the internal energy per unit volume; is the strain rate.

[0134] The conservation equations for mass, momentum, and energy can be written in Euler form as follows:

[0135]

[0136]

[0137]

[0138] Where ρ is the material density; v is the material velocity; σ is the Cauchy stress; b is the body force; e is the internal energy per unit volume; is the strain rate.

[0139] In a specific embodiment, Figure 4 The surface settlement and slurry pressure distribution results of the simulation calculation are extracted for the change process of the slurry volume fraction cloud map at every 2s interval, and compared with the experimental data, such as Figure 5 and Figure 6 As shown, the feasibility and rationality of the present invention are verified, and finally the slurry pressure, surface settlement, vertical displacement of the soil around the tunnel and the soil pressure are analyzed. The present invention solves the problem of synchronous grouting simulation of the shield tail in soft soil in the field of tunnel and underground engineering technology, is more economical and reasonable, and more in line with actual needs, and can be effectively applied in the field of tunnel and underground engineering technology.

[0140] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0141] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for simulating synchronous grouting of shield tail in shield construction in soft soil, characterized in that: include: Construct a three-dimensional finite element model of synchronous grouting of the shield tail and establish the geometric components of the three-dimensional finite element model; Get the physical parameters of the geometric components and set the material properties and state equations for the geometric components; Select the explicit time integration method and set the time analysis step and time increment step; Specify the mesh element type and mesh the three-dimensional finite element model of synchronous grouting at the shield tail; Set contact properties, boundary conditions and predefined fields for geometric components; The regional initialization is performed, and after the initialization, the fluid-solid coupling calculation of the three-dimensional finite element model is performed to obtain the simulation results of the synchronous grouting of the shield tail and analyze them.

2. The method for simulating synchronous grouting of shield tail in soft soil shield construction according to claim 1, characterized in that: The geometric components include Euler components and Lagrangian components. The Euler components are the grouting pipe and the grouting area, and the Lagrangian components are the soil, the lining continuum and the injected grout.

3. The method for simulating synchronous grouting of shield tail in soft soil shield construction according to claim 2, characterized in that: The state equation is a linear US-UP Hugoniot form of the Mie-Grüneisen state equation to model the slurry state equation. The linear US-UP state equation model is used to simulate the incompressible flow controlled by the Navier-Stokes motion equation.

4. The method for simulating synchronous grouting of shield tail in shield construction in soft soil according to claim 1, characterized in that: The obtaining of physical parameters of the geometric components and setting material properties for the geometric components includes: The soil was subjected to particle grading measurement and triaxial compression test to obtain soil physical parameters, and the material properties were assigned to the soil in the three-dimensional finite element model of synchronous grouting at the shield tail. Conducting performance tests on the synchronous grouting slurry to obtain the slurry physical parameters; Rheological tests were carried out on the synchronous grouting slurry to obtain the rheological parameters of the slurry, and the rheological curve was established. The rheological curve was fitted to obtain the rheological model of the slurry, and the material properties were given to the slurry in the three-dimensional finite element model of synchronous grouting at the shield tail.

5. The method for simulating synchronous grouting of shield tail in shield construction in soft soil according to claim 1, characterized in that: The specified grid unit type includes: setting the soil, lining continuum and injected slurry as Lagrangian grid components, setting the grouting pipe and grouting area as Eulerian grid components, the Lagrangian component adopts the 8-node C3D8R unit, and the Eulerian component adopts the 8-node EC3D8R unit.

6. The method for simulating synchronous grouting of shield tail in soft soil shield construction according to claim 1, characterized in that: The meshing of the shield tail synchronous grouting three-dimensional finite element model comprises: The mesh near the grouting area of ​​the Lagrangian component is encrypted, and the sparse mesh is used in the area outside the encrypted area. The mesh of the Euler component is encrypted. After the mesh division is completed, the mesh properties are adjusted and all are changed to explicit meshes; The flow of slurry in the Euler grid is tracked by calculating the Euler volume fraction EVF of the slurry in each unit. If the slurry completely fills the Euler unit, the EVF is 1; if there is no slurry in the Euler unit, the EVF is 0; if the EVF of the slurry in a certain Euler unit is greater than 0 and less than 1, the rest of the unit will be automatically set to an empty area; The fluid volume fraction method is used to track the geometric boundary of the injected slurry. The geometric boundary of the slurry is determined based on the EVF of the slurry and the empty area within the Eulerian unit. In each unit, the interface between the slurry and the empty area is determined by a straight line.

7. The method for simulating synchronous grouting of shield tail in shield construction in soft soil according to claim 1, characterized in that: The setting of contact attributes includes: adopting a penalty function contact method, wherein normal contact adopts hard contact; The outer radius of the Euler region is slightly larger than the outer diameter of the gap ring at the shield tail, allowing the grout to penetrate into the Lagrangian region in a small area. The grout is allowed to deform temporarily in the Lagrangian region, allowing the soil to pass through the Euler domain without resistance until it encounters an Euler unit with a non-zero EVF; In the penalty function contact method, the velocity of the soil boundary generates a kinetic force on the grout region, while the grout generates a pressure on the soil region.

8. The method for simulating synchronous grouting of shield tail in shield construction in soft soil according to claim 1, characterized in that: The boundary conditions of the geometric components include: In the initial analysis step, no changes in the flow velocity boundary conditions are set; In the dynamic display analysis step, change the flow velocity in the horizontal direction; The boundary condition of the Euler component is to set the velocity boundary of the Euler component in the x, y, and z directions to 0, that is, to fully constrain the velocity; In the subsequent dynamic display analysis step, the horizontal flow velocity is adjusted.

9. The method for simulating synchronous grouting of shield tail in soft soil shield construction according to claim 1, characterized in that: The predefined field includes: setting an initial slurry area at the grouting hole position, changing void to 0 after selecting the area to achieve full filling, and initializing the Euler area to an empty area without any material properties.

10. A shield tail synchronous grouting simulation system for shield construction in soft soil, characterized in that: include: Construction module: used to construct the three-dimensional finite element model of the synchronous grouting of the shield tail and establish the geometric components of the three-dimensional finite element model; Fitting module: used to obtain the physical parameters of geometric components and set material properties and state equations for geometric components; Method selection module: used to select explicit time integration method and set time analysis step and time increment step; Meshing module: used to specify the mesh unit type and mesh the three-dimensional finite element model of synchronous grouting at the shield tail; Setting module: used to set contact properties, boundary conditions of geometric components and predefined fields; Simulation analysis module: used for regional initialization, after which the fluid-solid coupling calculation of the three-dimensional finite element model is performed to obtain the shield tail synchronous grouting simulation results and perform analysis.

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