CN116305455A - OpenSees-based shield tunnel-soil body power interaction simulation method - Google Patents
OpenSees-based shield tunnel-soil body power interaction simulation method Download PDFInfo
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Abstract
The invention discloses a shield tunnel-soil body power interaction simulation method based on OpenSees, which comprises the following steps: s1: setting boundary conditions, and establishing a tunnel-soil body power interaction finite element model; s2: carrying out gravity analysis on the tunnel-soil body dynamic interaction finite element model; s3: zero clearing treatment is carried out on soil displacement; s4: adding a shield tunnel segment, a bolt at a joint and compression-resistant rubber gasket material units and material information, and setting a contact surface between a tunnel and a soil body; s5: binding a nonlinear beam unit based on a fiber section on a segment unit, and simulating nonlinear characteristics of the segment; s6: the soil body property is changed from linear elasticity to elastoplasticity; s7: performing incremental dynamic analysis on the model, wherein an initial state adopts an initial stress field of soil body, and earthquake excitation is applied to the bottom of the model; according to the method, the earthquake resistance of the tunnel is predicted and estimated through a shield tunnel earthquake response refined numerical modeling and calculating method.
Description
Technical Field
The invention relates to the technical field of tunnel soil safety, in particular to a shield tunnel-soil power interaction simulation method based on OpenSees.
Background
In recent years, tunnel engineering in China gradually develops along with economic prosperity, and becomes one of important routes for interconnection and interworking between regions. The tunnel engineering has the characteristic that the whole engineering is buried underground, and the safety and the permanence of the tunnel engineering can be ensured to the greatest extent only by fully considering the earthquake effect. The earthquakes often lead to liquefaction of soft soil layers with higher underground water levels, such as silt, saturated silt soil, sand soil layers and the like, the remolding of the soil bodies extrudes the tunnels in all directions, and the tunnels are settled, displaced and even destroyed along with the extrusion, so that serious accidents and casualties are caused. The soil liquefaction in the earthquake of the Japan-Saka god seriously damages subway stations and section tunnels, and large-scale liquefaction phenomena under the strong earthquake effect occur in a plurality of places such as the earthquake of the Turkish and the large earthquake of the Wenchuan. The scholars at home and abroad try to establish tunnel-soil body interaction limited models of liquefiable soil layer seeds by adopting different methods so as to predict and evaluate the shock resistance of the tunnel.
The existing tunnel-soil body interaction model mainly establishes a two-dimensional model under the plane strain assumption by a finite element method, and a plurality of entity units are used for simulating soil layers, beam units are used for simulating a bent structure such as a duct piece unit, and column units are used for simulating a compressed structure such as a pile foundation. Or establishing a three-dimensional model, and simulating the tunnel structure by adopting an elastic model.
The actual tunnel structure is not a simple bent rod piece under the action of soil body compressive stress, and the nonlinear property of the tunnel structure is considered, and the mutual influence relation between soil pressure and lining is considered. Most of the existing models do not consider transverse connection among lining segment blocks and longitudinal connection among segment rings, stress-strain response of soil layers and lining materials is regarded as being changed in an elastic range, a tunnel structure is regarded as an equivalent integral ring, research focuses on integral power and deformation of the tunnel, and influence of a joint structure serving as the weakest part of the tunnel on stress of the tunnel structure is ignored. In the research of a tunnel-soil body interaction model in a liquefiable stratum, the influence of the nonlinear property of a segment and the opening amount of a joint on tunnel deformation is not considered in most parts.
Disclosure of Invention
In order to more accurately evaluate the dynamic interaction between the tunnel and the soil body and predict the tunnel deformation condition under the earthquake action, the invention provides a novel shield tunnel earthquake reaction refinement numerical modeling and calculating method for predicting and evaluating the earthquake resistance of the tunnel.
The invention provides the following technical scheme:
a shield tunnel-soil body power interaction simulation method based on OpenSees comprises the following steps:
s1: setting boundary conditions, and establishing a tunnel-soil body power interaction finite element model;
s2: defining soil material properties, and carrying out gravity analysis on a tunnel-soil dynamic interaction finite element model;
s3: under the premise that the initial stress state of the soil body is kept unchanged, carrying out zero clearing treatment on the soil body displacement;
s4: adding a shield tunnel segment, a bolt at a joint, a compression-resistant rubber gasket material unit and material information, and setting a contact surface between a tunnel and a soil body;
s5: a nonlinear beam unit based on a fiber section is bound on the side edge of the duct piece unit, and the nonlinear characteristic of the duct piece is simulated;
s6: the soil body property is changed from linear elasticity to elastoplasticity;
s7: incremental dynamic analysis is performed on the model, and seismic excitation is applied to the bottom of the model.
Preferably, in the step S1, a dangerous section soil region is selected, a two-dimensional tunnel-soil dynamic interaction finite element model is established, and a two-dimensional tunnel-soil is established by adopting a middle 1/3 breadth section of a single-layer lining ring structureThe physical power is interacted with the finite element model and numerical calculation is carried out, the longitudinal width of the whole model is set to be 1/3 of the width of the lining ring, wherein the maximum height h of the grid size of the numerical model max The selection is determined by:
wherein v is s Representing shear wave velocity of the softest soil layer; f (f) max Representing the maximum frequency in the input ground motion.
Preferably, in the step S1, the boundary conditions of the tunnel-soil body dynamic interaction finite element model are set as follows:
(1) The displacement free ends at the same height node are bound at two sides of the model, so that two opposite vertical edges at two sides of the model can be ensured to move simultaneously under the action of external load;
(2) The degree of freedom in the vertical direction of all nodes is fixed at the bottom of the model, and as the nodes with the same height at the two sides of the model are bound, the nodes at the two sides of the bottom of the model are completely fixed, besides the nodes, the horizontal direction of the bottom is not limited, and the vibration excitation is input by using the direction;
(3) Setting watertight boundaries at the bottom and the side surfaces of the model, setting the initial pore pressure of all nodes of the soil body at the surface and above the underground water line to be 0, and fixing all pore pressure degrees of freedom;
(4) At the free field boundary of the model, respectively setting a thicker free field earth column simulation free field boundary at two sides of the model on the basis of the original model, wherein the thickness is 700-800 times of the original model thickness;
(5) In the aspect of the boundary treatment of free field soil columns at two ends of the model, the same as the original model soil body boundary treatment, the displacement free ends of nodes at the same height at two sides of the soil column (left and right) are bound to ensure that the nodes at two sides of the soil column can move together in the horizontal and vertical directions, and the degree of freedom of all nodes at the bottom of the soil column in the vertical direction and the degree of freedom of two nodes at the outermost side of the bottom in the horizontal direction are fixed; in the aspect of pore pressure treatment, the pore pressure degree of freedom of all soil mass nodes at the earth surface of the earth column and above the underground water line is fixed, and the initial pore pressure is set to be 0; and finally, connecting the soil columns at the two sides with the original model, and binding the free field soil column at the same height with the displacement free ends of the corresponding side nodes of the soil body of the original model so as to enable the free field soil column and the displacement free ends to move together.
Preferably, in the step S2, for the liquefiable saturated soil body, a water-soil coupling unit in openses, i.e., a fourdernodequadup unit, is adopted to simulate saturated sand in the numerical model; for non-liquefied soil types, simulation is performed by using a multi-yield surface plasticity constitutive relation.
Preferably, in the step S2, during the application of gravity load, the soil material behavior is linear elastic, and in the subsequent fast dynamic loading phase, the soil stress-strain response is converted into elastoplasticity by the material update process.
Preferably, in the step S4, the tunnel-soil body contact surface is set as a thin layer interface unit, the thickness of the set unit is 0.1m, and the position of the unit is between the periphery of the tunnel lining and the adjacent soil body.
Preferably, in step S4, the zero length unit is used to simulate the bolt and the rubber compression-resistant gasket in the joint structure, the zero length unit simulating the connection bolt and the rubber compression-resistant gasket binds the corresponding nodes sharing the same coordinate position on the contact surface of two adjacent duct pieces, and the arrangement direction of the units is perpendicular to the contact surface of the duct pieces.
More preferably, rubber compression-resistant gaskets and connecting bolts are simulated in the direction of the segment contact surface. Rubber compression-resistant gasket
The friction force and the contact pressure between adjacent duct pieces can be approximately simulated by using a uniaxial elastic material; the uniaxial elastic material
The tangential modulus E of the required parameter of the model is calculated by the following formula:
c wherein E represents the elastic modulus of the segment; i represents the section moment of inertia of the segment; l represents a segment ringA width; n represents a bolt
b b Number of pieces; g represents bolt shear modulus; s represents the cross-sectional area of the bolt; m represents a rectangular section coefficient; l represents the length of the connecting bolt;
the connecting bolt uses a uniaxial Giuffre-Mengo tto-Pinto reinforcing bar mould section bar with isotropic strain hardening
The material is Steel02 in OpenSees.
Compared with the prior art, the invention has at least the following advantages:
1. the invention adopts a dynamic time domain finite element method, and can conveniently simulate various complex stratum conditions and structural forms; considering the soil liquefaction effect, the same grid unit and different constitutive types are adopted for the liquefiable soil and the non-liquefiable soil, so that the true deformation condition between the soil and the tunnel can be reflected, and the applicability of the invention to various tunnel projects is greatly improved;
2. the invention uses linear elastic soil body material during the gravity load application period of the finite element model, and then updates the linear elastic soil body material into elastoplastic soil body material in the earthquake dynamic loading stage, thereby accurately simulating the stress-strain response of the tunnel structure under the earthquake action; simulating nonlinear material properties and geometric characteristics of the segment by adopting a composite unit of a nonlinear beam unit and a quadrilateral solid unit based on a fiber section;
3. according to the invention, the thin-layer contact surface unit is arranged between the contact surface of the tunnel and the soil body, so that the interaction between the structure and the soil body is effectively simulated, and the accuracy of the model is greatly improved;
4. according to the invention, the zero length unit is adopted to simulate the rubber compression-resistant gaskets and bolts between the duct pieces, so that the abrupt change of contact stress and bolt connecting force between adjacent duct pieces caused by the opening and dislocation phenomenon of the joint structure is accurately simulated.
Drawings
The invention will be further described with reference to the accompanying drawings, in which embodiments do not constitute any limitation of the invention, and other drawings can be obtained by one of ordinary skill in the art without inventive effort from the following drawings.
FIG. 1 is a flow chart of a shield tunnel-soil body power interaction simulation method based on OpenSees in an embodiment of the invention;
FIG. 2 is a schematic diagram of a numerical model of shield tunnel-soil body power interaction according to an embodiment of the present invention;
FIG. 3 is a schematic cross-sectional view of a tunnel and a schematic thickness of a contact surface unit in an embodiment of the invention;
FIG. 4 is a schematic illustration of a simulation of rubber gaskets and tie bolts between tunnel segments using zero length units in accordance with an embodiment of the present invention;
FIG. 5 is a schematic diagram of the location and binding of nonlinear beam units and quadrilateral physical units according to an embodiment of the present invention.
Detailed Description
A method for simulating power interactions of a shield tunnel and a soil body based on OpenSees is described in further detail below with reference to specific embodiments, which are only for comparison and explanation purposes, and the present invention is not limited to these embodiments.
Example 1
Referring to fig. 1, the OpenSees-based shield tunnel-soil body power interaction simulation method provided by the embodiment predicts and evaluates the earthquake resistance of a tunnel through a shield tunnel earthquake response refinement numerical modeling and calculating method, and includes the following steps:
s1: setting boundary conditions, and establishing a tunnel-soil body power interaction finite element model;
s2: defining soil material properties, and carrying out gravity analysis on a tunnel-soil dynamic interaction finite element model;
s3: under the premise that the initial stress state of the soil body is kept unchanged, carrying out zero clearing treatment on the soil body displacement;
s4: adding a shield tunnel segment, a bolt at a joint, a compression-resistant rubber gasket material unit and material information, and setting a contact surface between a tunnel and a soil body;
s5: a nonlinear beam unit based on a fiber section is bound on the side edge of the duct piece unit, and the nonlinear characteristic of the duct piece is simulated;
s6: the soil body property is changed from linear elasticity to elastoplasticity;
s7: incremental dynamic analysis is performed on the model, and seismic excitation is applied to the bottom of the model.
Preferably, in the step S1, a dangerous section soil region is selected, a two-dimensional tunnel-soil body dynamic interaction finite element model is established, the two-dimensional tunnel-soil body dynamic interaction finite element model established by a 1/3 breadth section in the middle of a single-layer lining ring structure is adopted, numerical calculation is performed, the longitudinal width of the whole model is set to be 1/3 lining ring width, wherein the maximum height h of the grid size of the numerical model max The selection is determined by:
wherein v is s Representing shear wave velocity of the softest soil layer; f (f) max Representing the maximum frequency in the input ground motion.
Preferably, in the step S1, the boundary condition setting step of the tunnel-soil body dynamic interaction finite element model is as follows:
(1) The displacement free ends at the same height node are bound at two sides of the model, so that two opposite vertical edges at two sides of the model can be ensured to move simultaneously under the action of external load;
(2) The degree of freedom in the vertical direction of all nodes is fixed at the bottom of the model, and as the nodes with the same height at the two sides of the model are bound, the nodes at the two sides of the bottom of the model are completely fixed, besides the nodes, the horizontal direction of the bottom is not limited, and the vibration excitation is input by using the direction;
(3) Setting watertight boundaries at the bottom and the side surfaces of the model, setting the initial pore pressure of all nodes of the soil body at the surface and above the underground water line to be 0, and fixing all pore pressure degrees of freedom;
(4) At the free field boundary of the model, respectively setting a thicker free field earth column simulation free field boundary at two sides of the model on the basis of the original model, wherein the thickness is 700-800 times of the original model thickness;
(5) In the aspect of the boundary treatment of free field soil columns at two ends of the model, the same as the original model soil body boundary treatment, the displacement free ends of nodes at the same height at two sides of the soil column (left and right) are bound to ensure that the nodes at two sides of the soil column can move together in the horizontal and vertical directions, and the degree of freedom of all nodes at the bottom of the soil column in the vertical direction and the degree of freedom of two nodes at the outermost side of the bottom in the horizontal direction are fixed; in the aspect of pore pressure treatment, the pore pressure degree of freedom of all soil mass nodes at the earth surface of the earth column and above the underground water line is fixed, and the initial pore pressure is set to be 0; and finally, connecting the soil columns at the two sides with the original model, and binding the free field soil column at the same height with the displacement free ends of the corresponding side nodes of the soil body of the original model so as to enable the free field soil column and the displacement free ends to move together.
Preferably, in the step S2, for the liquefiable saturated soil body, a water-soil coupling unit in openses, i.e., a fourdernodequadup unit, is adopted to simulate saturated sand in the numerical model; for non-liquefied soil types, simulation is performed by using a multi-yield surface plasticity constitutive relation.
Preferably, in the step S2, during the application of gravity load, the soil material behavior is linear elastic, and in the subsequent fast dynamic loading phase, the soil stress-strain response is converted into elastoplasticity by the material update process.
Preferably, in the step S4, the tunnel-soil body contact surface is set as a thin layer interface unit, the thickness of the set unit is 0.1m, and the position of the unit is between the periphery of the tunnel lining and the adjacent soil body.
Preferably, in step S4, the zero length unit is used to simulate the bolt and the rubber compression-resistant gasket in the joint structure, the zero length unit simulating the connection bolt and the rubber compression-resistant gasket binds the corresponding nodes sharing the same coordinate position on the contact surface of two adjacent duct pieces, and the arrangement direction of the units is perpendicular to the contact surface of the duct pieces.
The material used for the tie bolt in this example was a uniaxial Giuffre-Menegotto-Pinto bar model with isotropic strain hardening, and the type of material used was Steel02 material in OpenSees.
More preferably, a uniaxial elastic material is arranged in the direction of the contact surface of the duct piece, and the friction force between the uniaxial elastic material and the duct piece is approximately simulated; the tangential modulus E of the parameters required by the uniaxial elastic material model is calculated by the following formula:
wherein E is c Representing the elastic modulus of the segment; i represents the section moment of inertia of the segment; l represents the segment ring width; n represents the number of bolts; g b Representing the shear modulus of the bolt; s is S b Representing the cross-sectional area of the bolt; m represents a rectangular section coefficient; l represents the length of the connecting bolt.
A material model for the rubber compression-resistant liner and a tangential modulus calculating method thereof. The friction force in the direction of the contact surface of the segment is simulated by taking the properties of the segment and the bolt into consideration.
Example 2
The openses-based shield tunnel-soil body power interaction simulation method provided by the embodiment specifically comprises the following steps:
s1: setting boundary conditions, and establishing a tunnel-soil body power interaction finite element model;
and selecting a dangerous section soil domain, and establishing a two-dimensional finite element model. A finite element model is built and numerical calculation is carried out by adopting a middle 1/3 breadth section of a single-layer lining ring structure, and the calculation efficiency can be greatly improved by adopting a full breadth model of each ring lining of a tunnel instead of adopting a full breadth model of each ring lining of a tunnel. The overall model longitudinal width was set to 1/3 of the liner ring width.
The numerical model mesh size selection is determined as the maximum height hmax of the model mesh size, determined by:
wherein v is s Representing shear wave velocity of the softest soil layer; f (f) max Representing the maximum frequency in the input ground motion.
The specific setting steps of the boundary conditions are as follows:
(1) The two sides of the model are bound with the free displacement ends at the same height node, so that two opposite vertical edges of the two sides of the model can move simultaneously under the action of external load, and the two vertical edges are used for effectively reflecting the boundary effect of the layered shear deformation soil box and simulating the shear movement of the soil body under the action of the earthquake vibration load;
(2) The degree of freedom in the vertical direction of all nodes is fixed at the bottom of the model, and as the nodes with the same height at the two sides of the model are bound, the nodes at the two sides of the bottom of the model are completely fixed, besides the nodes, the horizontal direction of the bottom is not limited, and the vibration excitation is input by using the direction;
(3) Setting watertight boundaries at the bottom and the side surfaces of the model, setting the initial pore pressure of all nodes of the soil body at the surface and above the underground water line to be 0, and fixing all pore pressure degrees of freedom so as to meet the actual engineering soil liquefaction condition adopted by the model;
(4) At the free field boundary of the model, a thicker free field earth column is arranged at each side of the model on the basis of the original model to simulate the free field boundary, the thickness is set to be 700-800 times the original model thickness, and in the method, the thickness is 500m, and the width is set to be 1m;
(5) In the aspect of the processing of the free field soil column boundaries at two ends of the model, the same as the processing of the soil body boundaries of the original model, the displacement free ends of the nodes at the same height at two sides of the soil column (left and right) are bound to ensure that the nodes at two sides of the soil column can move together in the horizontal and vertical directions, and the degrees of freedom of all the nodes at the bottom of the soil column in the vertical direction and the degrees of freedom of the nodes at the outermost side of the bottom in the horizontal direction are fixed. In the aspect of pore pressure treatment, the pore pressure degree of freedom of all soil mass nodes at the earth surface of the earth column and above the underground water line is fixed, and the initial pore pressure is set to be 0. Finally, the two side earth columns are connected with the original model, as shown in fig. 2, the free field earth column at the same height and the displacement free ends of the corresponding side nodes of the original model soil body are bound (equalDOF) so as to move together.
S2: defining soil material properties, and carrying out gravity analysis on a tunnel-soil dynamic interaction finite element model;
and for the liquefiable saturated soil in the model, simulating saturated sand in the numerical model by adopting a water-soil coupling unit in OpenSees, namely a FourdNodeQuadUP unit. Each node of the unit has three degrees of freedom, including DOF1, DOF2 for describing the displacement of the solid in the x, y directions, and DOF3 for describing the fluid pressure, i.e. the pore pressure. The method uses a PressureDependMultiYIeld material to be applied to the solid-fluid complete coupling unit FourdEQUADUP unit with very low permeability so as to simulate the soil earthquake response under the condition of completely no drainage in the tunnel-soil dynamic interaction finite element model.
And simulating the non-liquefied soil body type in the model by using a multi-yield-surface plastic constitutive relation, wherein the yield surface type is Von Mises multi-yield surface so as to reflect the elastoplasticity characteristic of soil body shear hysteresis and the permanent deformation of soil body. The constitutive model adopts a PressureRendependMultiYIeld material type and is applied to a FourdNodeQuadUP unit.
During application of gravity loading, the soil material behavior is linear elastic, and in the subsequent fast dynamic loading phase, the soil stress-strain response is converted into elastoplasticity through material update processing.
S3: under the premise that the initial stress state of the soil body is kept unchanged, carrying out zero clearing treatment on the soil body displacement;
s4: adding a shield tunnel segment, a bolt at a joint, a compression-resistant rubber gasket material unit and material information, and setting a contact surface between a tunnel and a soil body;
according to the embodiment of the invention, the two-dimensional finite element model is built by adopting the composite unit of the nonlinear beam unit and the quadrilateral entity unit based on the fiber section. The former is used to represent material properties, reflecting reinforced concrete cross-sectional properties, and the latter is used to reflect geometry of the structure, providing a volumetric representation of the structure.
In the nonlinear beam unit based on the fiber section, which is used in the invention, a Giuffre-Mengo tto-Pinto model is adopted to simulate tunnel segment Steel bars, and the type of the used material is Steel02 material in OpenSees.
The invention adopts a uniaxial Concrete material with tensile strength and linear stretching softening to simulate tunnel segment core Concrete and a Concrete protective layer, namely Concrete02 material in OpenSees.
In the quadrilateral solid unit, an elastic-complete plastic drager-Prager model is adopted to simulate lining concrete. The stiffness in the composite unit is mainly provided by the nonlinear beam units based on fiber cross sections, thus weakening the stiffness of the quadrangular entity units. The stiffness of the nonlinear beam unit based on the fiber section is set to be the same as that of the elastic cantilever, and the modulus of the quadrilateral unit is set to be 0.0001 times of the actual modulus of the elastic cantilever.
According to the invention, a thin layer interface unit is arranged at the junction of the tunnel structure and the soil body so as to consider the rigidity change of the structure-soil body unit. The reinforced concrete segment has larger rigidity difference with the adjacent soil body, the tunnel-soil body contact surface is set as a thin layer interface unit, the thickness of the unit is set to be 0.1m, and the position of the unit is between the periphery of the tunnel lining and the adjacent soil body. The thin layer interface unit is schematically shown in fig. 3:
according to the invention, the difference of rigidity between the structure and the soil body is considered, and the thin layer interface unit between the structure and the soil body is subjected to shearing parameter weakening treatment. Considering that the shield underground tunnel is integrally distributed in different soil layers, a segmented thin layer interface unit with weakened shearing parameters is adopted to simulate the tunnel-soil body contact surface. The shear parameter weakening coefficient was used 0.7.
The invention adopts a zero length unit to simulate the bolt and the rubber compression-resistant gasket in the joint structure, and the joint structure is schematically shown in fig. 4.
The zero length unit (zerolength element) of the invention has a unit length of zero and can bind two nodes at the same position. The zero length units simulating the connecting bolts and the rubber compression-resistant gaskets bind corresponding nodes sharing the same coordinate position on the contact surfaces of two adjacent duct pieces, and the arrangement directions of the units are all perpendicular to the contact surfaces of the duct pieces. The material of the connecting bolt is simulated by adopting a uniaxial Giuffre-Mengo tto-Pinto reinforcing bar model with isotropic strain hardening, the material type is Steel02 material in OpenSees, and the material of the rubber compression-resistant gasket is simulated by adopting a uniaxial elastic compression-resistant and non-tension material.
The invention fully simulates the earthquake response of the joint structure under the action of earthquake load, and the friction effect between the bolt and the contact surface of the duct piece is considered, so that the uniaxial elastic material is arranged in the direction of the contact surface of the duct piece, and the friction force between the bolt and the duct piece can be approximately simulated. The tangential modulus E of the parameters required for the uniaxial elastic material model can be calculated as follows:
wherein E is c Representing the elastic modulus of the segment; i represents the section moment of inertia of the segment; l represents the segment ring width; n represents the number of bolts; g b Representing the shear modulus of the bolt; s is S b Representing the cross-sectional area of the bolt; m represents a rectangular section coefficient; l represents the length of the connecting bolt.
S5: as shown in fig. 5, a nonlinear beam unit based on a fiber section is bound at the side of the segment unit, so that the nonlinear characteristic of the segment is simulated;
s6: the soil body property is changed from linear elasticity to elastoplasticity;
s7: and performing incremental dynamic analysis on the model, wherein the initial state adopts the soil body initial stress field, and earthquake excitation is applied to the bottom of the model.
Through the steps, the method for modeling and calculating the fine numerical value of the earthquake response of the shield tunnel can be established, target tunnel vulnerability analysis can be carried out through the method in the later period, a tunnel loss probability curve and a function recovery probability curve are drawn, the earthquake resistance of the tunnel is predicted, and the method becomes the basis for building the earthquake resistance toughness assessment framework of the tunnel.
The method provided by the embodiment of the invention has the key points that the full width model of each ring lining of the tunnel is replaced by the middle 1/3 width model of the single-layer lining replacement structure for calculation, so that the calculation efficiency is greatly improved; considering the soil liquefaction effect, the nonlinear characteristics of the duct pieces and the joint structures of the joints of the adjacent duct pieces, the liquefaction characteristics of saturated sand, the nonlinear characteristics of steel bars and concrete in the duct pieces, the deformation and dislocation of the joint of the duct pieces and the like can be accurately simulated under the action of earthquake load.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.
Claims (8)
1. A shield tunnel-soil body power interaction simulation method based on OpenSees is characterized in that the earthquake resistance of a tunnel is predicted and estimated by a shield tunnel earthquake reaction refinement numerical modeling and calculating method, and the method comprises the following steps:
s1: setting boundary conditions, and establishing a tunnel-soil body power interaction finite element model;
s2: defining soil material properties, and carrying out gravity analysis on a tunnel-soil dynamic interaction finite element model;
s3: under the premise that the initial stress state of the soil body is kept unchanged, carrying out zero clearing treatment on the soil body displacement;
s4: adding a shield tunnel segment, a bolt at a joint, a compression-resistant rubber gasket material unit and material information, and setting a contact surface between a tunnel and a soil body;
s5: a nonlinear beam unit based on a fiber section is bound on the side edge of the duct piece unit, and the nonlinear characteristic of the duct piece is simulated;
s6: the soil body property is changed from linear elasticity to elastoplasticity;
s7: and performing incremental dynamic analysis on the model, wherein the initial state adopts the soil body initial stress field, and earthquake excitation is applied to the bottom of the model.
2. The method for simulating power interaction between shield tunnel and soil body based on OpenSees according to claim 1,the method is characterized in that in the step S1, a dangerous section soil domain is selected, a two-dimensional tunnel-soil body power interaction finite element model is established, the two-dimensional tunnel-soil body power interaction finite element model established by a 1/3 breadth section in the middle of a single-layer lining ring structure is adopted, numerical calculation is carried out, the longitudinal width of the whole model is set to be 1/3 lining ring width, wherein the maximum height h of the grid size of the numerical model max The selection is determined by:
wherein v is s Representing shear wave velocity of the softest soil layer; f (f) max Representing the maximum frequency in the input ground motion.
3. The OpenSees-based shield tunnel-soil body power interaction simulation method according to claim 1, wherein in the step S1, the boundary condition setting step of the tunnel-soil body power interaction finite element model is as follows:
(1) The displacement free ends at the same height node are bound at two sides of the model, so that two opposite vertical edges at two sides of the model can be ensured to move simultaneously under the action of external load;
(2) The degree of freedom in the vertical direction of all nodes is fixed at the bottom of the model, and as the nodes with the same height at the two sides of the model are bound, the nodes at the two sides of the bottom of the model are completely fixed, besides the nodes, the horizontal direction of the bottom is not limited, and the vibration excitation is input by using the direction;
(3) Setting watertight boundaries at the bottom and the side surfaces of the model, setting the initial pore pressure of all nodes of the soil body at the surface and above the underground water line to be 0, and fixing all pore pressure degrees of freedom;
(4) At the free field boundary of the model, respectively setting a thicker free field earth column simulation free field boundary at two sides of the model on the basis of the original model, wherein the thickness is 700-800 times of the original model thickness;
(5) In the aspect of the boundary treatment of free field soil columns at two ends of the model, the same as the original model soil body boundary treatment, the displacement free ends of nodes at the same height at two sides of the soil column (left and right) are bound to ensure that the nodes at two sides of the soil column can move together in the horizontal and vertical directions, and the degree of freedom of all nodes at the bottom of the soil column in the vertical direction and the degree of freedom of two nodes at the outermost side of the bottom in the horizontal direction are fixed; in the aspect of pore pressure treatment, the pore pressure degree of freedom of all soil mass nodes at the earth surface of the earth column and above the underground water line is fixed, and the initial pore pressure is set to be 0; and finally, connecting the soil columns at the two sides with the original model, and binding the free field soil column at the same height with the displacement free ends of the corresponding side nodes of the soil body of the original model so as to enable the free field soil column and the displacement free ends to move together.
4. The OpenSees-based shield tunnel-soil body power interaction simulation method according to claim 1, wherein in the step S2, for the liquefiable saturated soil body, a water-soil coupling unit in OpenSees, namely a fourdonodequadrup unit, is adopted to simulate saturated sand in the numerical model; for non-liquefied soil types, simulation is performed by using a multi-yield surface plasticity constitutive relation.
5. The OpenSees-based shield tunnel-soil body dynamic interaction simulation method according to claim 1, wherein in the step S2, the soil body material behavior is linear elastic during the application of gravity load, and the soil body stress-strain response is converted into elastoplasticity through the material update process in the subsequent fast dynamic loading stage.
6. The OpenSees-based shield tunnel-soil body power interaction simulation method according to claim 1, wherein in the step S4, a tunnel-soil body contact surface is set as a thin layer interface unit, the thickness of the set unit is 0.1m, and the unit is located between the periphery of the tunnel lining and the adjacent soil body.
7. The OpenSees-based shield tunnel-soil body power interaction simulation method according to claim 1, wherein in the step S4, a zero length unit is adopted to simulate a bolt and a rubber compression-resistant gasket in a joint structure, a zero length unit simulating a connecting bolt and a rubber compression-resistant gasket binds corresponding nodes sharing the same coordinate position on two adjacent duct piece contact surfaces, and the unit arrangement directions are all perpendicular to the duct piece contact surfaces.
8.The OpenSees-based shield tunnel-soil body dynamic interaction simulation method as claimed in claim 7, which is characterized in that Characterized in that the rubber compression-resistant gasket and the connecting bolt are simulated in the direction of the contact surface of the duct piece. Rubber compression-resistant gasket The uniaxial elastic material can be used for approximately simulating the friction force and the contact pressure between adjacent duct pieces; required by the uniaxial elastic material model The parameter tangential modulus E is calculated by the following formula:
c wherein E represents the elastic modulus of the segment; i represents the section moment of inertia of the segment; l represents the segment ring width; n represents the number of bolts;
b b g represents bolt shear modulus; s represents the cross-sectional area of the bolt; m represents a rectangular section coefficient; l represents the length of the connecting bolt; connecting screw
The bolt uses a uniaxial Giuffre-Mengo tto-Pinto bar form material with isotropic strain hardening
The type is Steel02 in OpenSees.
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| CN117216862A (en) * | 2023-11-09 | 2023-12-12 | 湖南大学 | Three-dimensional shield tunnel dynamic analysis model based on fiber beam unit |
| CN117216862B (en) * | 2023-11-09 | 2024-02-02 | 湖南大学 | Three-dimensional shield tunnel dynamic analysis model based on fiber beam unit |
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