CN102561395B - Three-dimensional fine modeling method oriented to immersed tube tunnel seismic design - Google Patents

Abstract

A three-dimensional simplified modeling method for an immersed tunnel, comprising: analyzing the structure of the immersed tunnel to determine the part to be modeled; defining the nodes on the axis of the immersed tunnel model; defining the units required for the immersed tunnel model; defining the material Properties and interface attributes; define the constraint relationship between the nodes of the simulated joint and the end points of the pipe joint; assemble the above-mentioned components into an immersed tunnel model and use it for calculation and analysis. The invention can simulate the initial compression of joints produced by hydraulic pressure bonding during the construction of immersed tube tunnels, accurately calculate the stress and opening amount of the joints, and realize the fine calculation of joint positions. The invention not only fully considers the analysis accuracy requirement, but also meets the calculation efficiency requirement, and has good engineering practicability.

Description

A three-dimensional refined modeling method for seismic design of immersed tube tunnels

technical field

The invention belongs to the field of underwater tunnel engineering and relates to a modeling method that can be used for the seismic design of immersed tube tunnels.

Background technique

The immersed tube method is a new construction method developed in the early 20th century to build underwater tunnels. Due to its unique advantages, the immersed tube method has become the preferred construction method for underwater tunnel construction in recent years. In the longitudinal seismic analysis of immersed tube tunnels, whether the established 3D analysis model is suitable or not involves the efficiency of calculation and the reliability of the results. Therefore, a reasonable 3D model of immersed tube tunnels is very important for seismic analysis.

In the past, most of the models used for seismic analysis of immersed tunnels used spring-mass models, and individual projects used full 3D refined models. Since the joints of immersed tube tunnels are less rigid than the pipe joints, they are often the weakest parts of the tunnel, and their stress and deformation are the key points in the project, especially the structural measures such as Gina waterstops and shear keys under the action of earthquakes. Performance directly affects the security of the tunnel. Gina waterstop is a super elastic material, in order to ensure its watertightness, it needs to meet the minimum compression requirement. Under the action of an earthquake, with the deformation of the joint, the amount of compression may decrease, resulting in the failure of the water seal. The shear key is the main anti-seismic structure of the joint, and its stress and deformation are directly related to the anti-seismic capacity of the tunnel. In the past, most of the models used for seismic analysis of immersed tunnels used spring-mass models, and individual projects used full 3D refined models. Although the calculation amount of the spring-mass model is small, the simulation of the joint is relatively rough, and the tension and compression, bending and shearing are simply simulated with one spring each, so the real compression and opening of the Gina waterstop cannot be calculated, nor can it be analyzed The force of the shear bond. This model cannot take into account the slippage of the pipe body caused by hydraulic compression during construction and the resulting initial compression of the joint, which will lead to the inability to accurately calculate important control conditions such as the opening of the joint in the subsequent seismic analysis, and the model cannot calculate Possible sliding of tunnel and soil under earthquake action. Therefore, the spring-mass model is not suitable for accurate calculation of joint locations. Although the full three-dimensional refined model can accurately calculate and analyze the force, deformation and opening of the tunnel joint, the calculation cost is too high and it is not suitable for the calculation and analysis in the century project.

Contents of the invention

The existing spring-mass model cannot simulate the hydraulic crimping of immersed tube tunnels, the existing spring-mass model cannot accurately calculate the force and opening of the joints, and the existing spring-mass model cannot simulate the shear bond and Gina stop. Due to the shortage of water strips and the disadvantages of high calculation cost of the full three-dimensional refined model, the purpose of the present invention is to provide a three-dimensional simplified modeling method for immersed tube tunnels.

In order to solve the problems of the technologies described above, the technical solution of the present invention comprises the following steps:

Step 1, carry out structural analysis on the immersed tube tunnel, and determine the part to be modeled;

Step 2, define the nodes on the axis of the immersed tunnel model;

Step 3, define the elements required for the immersed tunnel model, including: beam elements for simulating pipe joints, nonlinear spring elements for simulating Gina waterstops, spring and pot elements for simulating soil, and simulating Sliding elements for tunnels in contact with soil, spring elements for simulating shear bonds, etc.;

Step 4, set the elastic modulus and Poisson's ratio of the pipe joint material, determine the cross-sectional size, and set the parameters of the soil spring, sticky pot, shear key, and Gina waterstop;

Step 5, define the constraint relationship between the nodes of the simulated joint and the end points of the pipe joint;

Step 6, assemble the above-mentioned components into an immersed tunnel model, and use it for calculation and analysis.

Further, step 1 includes: determining the geometric position of the axis, the buried depth of the tunnel, and the distribution of the surrounding soil layers, and taking the part of the tunnel to be constructed by the buried pipe section method as the modeling range.

The nodes in step 2 include three parts: the nodes on the axis of the pipe joint, the nodes of the foundation spring and the sticky pot used to simulate the behavior of the soil, and the nodes at the end of the pipe along the perimeter of the cross section. The number of nodes on the axis of the pipe joint is related to It is related to the geometry of the beam element representing the pipe joint.

The units described in step 3 include: beam elements for simulating pipe joints, nonlinear spring elements for simulating Gina waterstops, spring and sticky pot elements for simulating soil, and sliding elements for simulating the contact between tunnel and soil element, a spring element for simulating a shear bond.

Step 4 includes: setting the elastic modulus and Poisson's ratio of the pipe joint material, determining the cross-sectional size, and setting the parameters of the earth spring, sticky pot, shear key, and Gina waterstop.

Step 5: set the nodes along the circumference of the joint and the end nodes of the pipe joint as rigid body constraints, and keep these nodes from generating relative displacement.

Further, a modeling method for the seismic design of immersed tube tunnels, including:

Step 1: Structural analysis of the tunnel structure to be designed, including: determining the geometric position of the axis, the buried depth of the tunnel, and the distribution of the surrounding soil layers. The immersed tube tunnel model includes pipe joints, foundation springs, sticky pots, sliding units, Gina waterstops, and shear keys;

Step 2, define the control nodes of the immersed tunnel model. The control nodes include three parts: nodes on the axis of the pipe joint, nodes of the foundation spring and sticky pot used to simulate soil behavior, and nodes along the perimeter of the cross-section at the end of the pipe joint. The number of nodes on the pipe joint axis is related to the geometric size of the beam element representing the pipe joint;

Step 3, define the unit used to simulate the immersed tunnel;

1) Simulation of pipe joints: Discretize the pipe joints into three-dimensional linear beam units on the basis of the joint axis nodes of the immersed tube tunnel defined in step 2, that is, define the end points of two adjacent nodes on the axis of each pipe joint as the unit 3D linear beam element;

2) Simulation of pipe joints: a) Simulation of Gina waterstop: Use several nonlinear spring elements to simulate the function of Gina waterstop. In step 2, the nodes along the perimeter of the cross-section at the end of each pipe section have been set. The corresponding nodes along the perimeter of the cross-section at the ends of the pipe joints on both sides of the joint are taken as the unit endpoints, and each pair of nodes is defined as a nonlinear spring unit;

b) Simulation of the shear bond: According to the actual arrangement position of each shear bond in the joint, find out the corresponding nodes of the nodes along the perimeter of the end faces of the pipe joints on both sides of the joint, and define the Cartesian connection element with each pair of corresponding nodes as the element endpoint; If the unit is used to simulate a horizontal shear bond, the shear bond stiffness in the horizontal direction should be defined in the unit; if it is a vertical shear bond, then the corresponding vertical shear bond stiffness should be defined; If there is also a numerical shear bond in the middle of the cross section, this method is also used to set the nodes of the shear bond according to the specific geometric position and define Cartesian connection elements between the corresponding nodes;

3) Soil simulation: take the node of the unit simulating soil behavior defined in step 2 as the end point, and define parallel spring units and sticky pot units in three directions of space respectively, so as to simulate the behavior of soil;

4) Simulation of soil-tunnel interaction: define the Cartesian & Cardan connection unit with the node on the axis of the pipe joint and the node on the side of the simulated soil behavior corresponding to its position near the pipe joint as the unit end point, except along the horizontal and longitudinal direction of the tunnel Except for the degrees of freedom, the rest of the degrees of freedom are set as rigid, and the friction coefficient of the soil-tunnel is set appropriately in the horizontal and vertical directions, and the direction of the normal force is defined as the vertical direction. A possible vertical slide is generated under;

Step 4, define material properties and interface properties;

1) Set material constants such as elastic modulus and Poisson's ratio of the joint material;

2) Determine the cross-sectional area of the pipe joint, the moment of inertia about the centroid axis, the product of inertia, the torsion constant, and the shear center position and other parameters through calculation;

3) Use appropriate theoretical calculations to determine the respective coefficients of the spring and the pot in the spring-pot parallel unit used to simulate the behavior of the soil;

4) Determine the force-compression nonlinear relationship curve of the Gina material;

Step 5, define the constraint relationship: set the nodes along the perimeter of the joint (including the nodes corresponding to the shear keys) and the nodes at the end of the joint as rigid body constraints, and keep these nodes without relative displacement; the nodes along the perimeter of the joint The nodes include the corresponding nodes of each shear key;

Step 6, assemble the above-mentioned components into an immersed tunnel model, and use it for calculation and analysis.

The invention makes up for the deficiencies of the above two models, can simulate the initial compression of joints produced by hydraulic pressure bonding during the construction of immersed tunnels, and accurately calculate the stress and opening of the joints. In this invention, the joint Gina waterstop is simulated as a number of springs arranged along the actual perimeter, and the shear key is simulated as a spring at the corresponding position, which realizes the refined calculation of the joint position. The invention not only fully considers the analysis accuracy requirement, but also meets the calculation efficiency requirement, and has good engineering practicability.

Description of drawings

Fig. 1 is a flowchart of a three-dimensional refined modeling method for the seismic design of an immersed tunnel in an example of the present invention.

Fig. 2 is a three-dimensional view of the example of the present invention used in the seismic design model of the immersed tube tunnel.

Fig. 3 is a three-dimensional view of the pipe joint model of the immersed tunnel.

Explanation of the numbers in the accompanying drawings:

1-Immersed tube tunnel pipe joint; 2-Foundation spring; 3-Stick pot; 4-Sliding unit; 5-Shear key; 6-Gina waterstop; Node; 9-right end point of left pipe joint; 10-left end point of right pipe joint; 11-left node of shear key; 12-right node of shear key; 13-rigid connection

Detailed ways

Below in conjunction with the accompanying drawings and embodiments, based on the general finite element software ABAQUS, the specific implementation of the present invention will be further described in detail.

Step 1: Structural analysis of the tunnel structure to be designed, including: determining the geometric position of its axis, the buried depth of the tunnel, and the distribution of surrounding soil layers. The part of the tunnel to be constructed by the buried pipe segment method is taken as the modeling range.

As shown in Figure 1, the immersed tunnel model includes pipe joints 1, foundation springs 2, sticky pots 3, sliding units 4, shear keys 5, Gina waterstops 6 and other parts.

Step 2, as shown in Figure 1, define the control nodes of the immersed tunnel model. The control nodes include three parts: nodes on the axis of the pipe joint, nodes of the foundation spring and sticky pot used to simulate soil behavior, and nodes along the perimeter of the cross-section at the end of the pipe joint. The number of nodes on the pipe joint axis is related to the geometric size of the beam element representing the pipe joint, which depends on the analysis accuracy and the length of the pipe joint, and also considers the calculation cost. Generally speaking, the larger the number of nodes, the higher the accuracy, but the higher the computational cost. Taking a node every five meters can better balance the calculation accuracy and calculation cost. . In this embodiment, each pipe section has a length of 180 meters and is divided into 32 beam units, so 33 nodes are set on the axis of each pipe section. The nodes of foundation springs and sticky pots used to simulate the behavior of soil can be obtained by the translation of the nodes on the axis of each pipe joint in space. Nodes can be set at intervals along the perimeter of the cross-section at the end of the pipe joint, and in this embodiment, a node is set every meter.

Step 3, define the unit used to simulate the immersed tunnel;

1) Simulation of pipe joints: as shown in Figure 1, the pipe joints are discretized into three-dimensional linear beam units on the basis of the joint axis nodes of immersed tunnel tunnels defined in step 2, that is, two adjacent beam units on the axis of each pipe joint Nodes define 3D linear beam elements for the endpoints of the element;

2) Simulation of pipe joints: a) Simulation of Gina waterstop: use several nonlinear spring elements to simulate the function of Gina waterstop. As shown in Figures 1 and 2, the nodes along the circumference of the cross-section at the ends of the pipe joints have been set in step 2, and the corresponding nodes along the circumference of the cross-section at the ends of the pipe joints on both sides of the joint are used as the unit endpoints. The nodes are defined as nonlinear spring elements;

b) Simulation of the shear bond: As shown in Figure 2, the shear bond is another main component of the joint except the Gina waterstop. According to the actual arrangement position of each shear bond in the joint, the corresponding nodes of the nodes along the perimeter of the pipe joint end faces on both sides of the joint are found, and each pair of corresponding nodes is used as the unit end point to define the Cartesian (Cartesian unit) connection unit. If the unit is used to simulate a horizontal shear key, the shear key stiffness in the horizontal direction should be defined in the unit; if it is a vertical shear key, the corresponding vertical shear key stiffness should be defined. If the tunnel to be designed also has numerical shear bonds in the middle of the joint cross-section, this method is also used to set the nodes of the shear bonds according to the specific geometric positions and define Cartesian connection elements between the corresponding nodes.

3) Soil simulation: As shown in Figure 1, take the node of the unit simulating soil behavior defined in step 2 as the endpoint, and define parallel spring units and sticky pot units in three directions in space to simulate soil behavior of the body;

4) Simulation of soil-tunnel interaction: as shown in Figure 1, the node on the axis of the pipe joint and the node on the side of the simulated soil behavior corresponding to the position of the unit near the pipe joint are used as the end points of the unit to define the Cartesian & Cardan (Flute Karl unit and universal joint unit) connection unit. Except for the degrees of freedom along the horizontal and longitudinal directions of the tunnel, the rest of the degrees of freedom are set as rigid. The appropriate soil-tunnel friction coefficient is set in the horizontal and vertical directions, and the direction of the normal force is defined as the vertical direction. This unit allows the possible longitudinal sliding of pipe joints under hydraulic pressure and earthquake;

Step 4, define material properties, interface properties, etc.;

1) Set material constants such as elastic modulus and Poisson's ratio of the joint material;

2) Determine the cross-sectional area of the pipe joint, the moment of inertia about the centroid axis, the product of inertia, the torsion constant, and the shear center position and other parameters through calculation.

3) Use appropriate theoretical calculations to determine the respective coefficients of the spring and the pot in the spring-pot parallel unit used to simulate the behavior of the soil;

4) Determine the force-compression nonlinear relationship curve of the Gina material;

Step 5, define the constraint relationship: set the nodes along the circumference of the joint and the end nodes of the pipe joint as rigid body constraints (if there is a vertical shear bond in the middle, the corresponding end point of the shear bond should be included), and keep these nodes No relative displacement occurs;

Step 6, assemble the above-mentioned components into an immersed tunnel model, and use it for calculation and analysis.

The above description of the embodiments is for those of ordinary skill in the art to understand and apply the present invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the embodiments herein. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (5)

1. for a modeling method for immersed tube tunnel seismic design, it is characterized in that: comprising:

Step 1, carries out structural analysis to immersed tube tunnel, determines and needs modeling part;

Step 2, defines the node on this immersed tube tunnel model axis;

Step 3, defines this immersed tube tunnel model and needs unit;

Step 4, definition material property, interface property;

Step 5, the restriction relation between node and this tube coupling end points of definition simulation joint area;

Step 6, is immersed tube tunnel model by above-mentioned each assembling parts, and for computational analysis;

Step 1 comprises: determine the geometric position of its axis, the buried depth in tunnel, and the distribution of soil layer around, getting the tunnel segment of intending with the construction of sunken tube method is modeling scope;

In step 2, node comprises three parts: node on tube coupling axis, for simulating the ground spring of soil body behavior and the node of sticky kettle and the tube coupling end node along cross section girth, on tube coupling axis, the quantity of node is relevant with the physical dimension of beam element that characterizes tube coupling.

2. the modeling method for immersed tube tunnel seismic design according to claim 1, is characterized in that: described in step 3, unit comprises: for simulate tube coupling beam element, simulation Gina waterstop nonlinear spring unit, for spring and the sticky kettle unit of simulating the soil body, the sliding unit contacting with the soil body for simulation tunnel, for simulating the spring unit of shear key.

3. the modeling method for immersed tube tunnel seismic design according to claim 1, it is characterized in that: step 4 comprises: modulus of elasticity, the poisson's ratio of setting tube coupling material, determine cross dimension, the parameter of soil spring, sticky kettle, shear key, Gina waterstop is set.

4. the modeling method for immersed tube tunnel seismic design according to claim 1, is characterized in that: in step 5: node and this tube coupling endpoint node along joint circumferential direction are set to Rigid Constraints, keep these nodes not produce relative displacement.

5. the modeling method for immersed tube tunnel seismic design according to claim 1, is characterized in that: comprising:

Step 1, the tunnel structure that proposes meter is carried out to structural analysis, comprise: determine the geometric position of its axis, the buried depth in tunnel, the distribution of soil layer around, getting the tunnel segment of intending with the construction of sunken tube method is modeling scope, and this immersed tube tunnel model comprises tube coupling, ground spring, sticky kettle, sliding unit, Gina waterstop, shear key;

Step 2, define the control node of this immersed tube tunnel model, control node and comprise three parts: node on tube coupling axis, for simulating the ground spring of soil body behavior and the node of sticky kettle and the tube coupling end node along cross section girth, on tube coupling axis, the quantity of node is relevant with the physical dimension of the beam element of sign tube coupling;

Step 3, definition is for simulating the unit of this immersed tube tunnel;

1) simulation of tube coupling: on the basis of the defined immersed tube tunnel tube coupling of step 2 axis node by discrete tube coupling be three-dimensional linear beam element, i.e. the three-dimensional linear beam element of the end points take adjacent two nodes on each tube coupling axis as unit definition;

2) simulation of tube coupling joint: a) simulation of Gina waterstop: with the effect of some nonlinear spring unit simulation Gina waterstops, the node of each tube coupling end along cross section girth has been set in step 2, corresponding node take tube coupling end, joint both sides along cross section girth, as cell terminals, will be defined as nonlinear spring unit between every pair of node;

B) simulation of shear key: the actual arrangement position according to each shear key at joint, find out the corresponding node of joint both sides tube coupling end face along the node of girth, the definition Cartesian linkage unit take every pair of corresponding node as cell terminals; If this unit should define the shear key rigidity of horizontal direction in this unit for dummy level shear key; If vertically shear key defines corresponding vertically shear key rigidity; Also there is vertical shear key if propose the tunnel of meter at middle part, joint cross section, adopt equally the method the node of shear key to be set and between corresponding node, to define Descartes's linkage unit according to concrete geometric position;

3) simulation of the soil body: take the node of unit of the simulation soil body behavior of definition in step 2 as end points, three directions define respectively spring unit in parallel and sticky kettle unit in space, simulates the behavior of the soil body with this;

4) the interactional simulation in the soil body-tunnel: take the node near tube coupling side of the unit of node on tube coupling axis and the simulation soil body behavior corresponding with its position as cell terminals definition Cartesian & Cardan linkage unit, except along the longitudinal degree of freedom of tunnel level, all the other degree of freedom are all set to rigidity, the friction factor in the suitable soil body-tunnel is longitudinally set in level, the direction of normal force is defined as vertical direction, and this unit allows tube coupling under waterpower crimping and geological process, to produce possible longitudinal sliding motion;

Step 4, definition material property, interface property;

1) material constant such as modulus of elasticity, poisson's ratio of joint material is set;

2) by the parameter such as area, moment of inertia, the product of inertia, torsion constant and the shear center position to centre of form axle in calculative determination tube coupling cross section;

3) adopt suitable theoretical calculative determination for simulating spring-sticky kettle unit medi-spring in parallel and the sticky kettle coefficient separately of soil body behavior;

4) determine power-decrement non-linear relation curve of Gina material;

Step 5, definition restriction relation: by the node along joint circumferential direction, comprise each shear key corresponding node, be set to Rigid Constraints with this joint endpoint node, keep these nodes without relative displacement; The described node along joint circumferential direction comprises each shear key corresponding node;

Step 6, is immersed tube tunnel model by above-mentioned each assembling parts, and for computational analysis.

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