Calculation Method for Seismic Response of Closely-Spaced Underground Structure Groups and Anti-Seismic Design Process

Abstract

The present invention discloses a method for calculating the seismic response of a group of closely spaced intersecting underground structures, and presents a corresponding seismic design process. By establishing calculation models of soil - a single typical underground structure and soil - a group of closely spaced intersecting underground structures, the main influencing factors affecting the seismic response of the system are determined, and influencing factors are recommended based on numerical parameter analysis. The complex interaction problem is simplified into a seismic analysis problem of a relatively mature single typical underground structure, realizing the seismic response analysis of a group of closely spaced intersecting underground structures under seismic action and a practical seismic design process, effectively solving the seismic design problem of a large number of emerging groups of intersecting underground structures at close range.

Description

Technical Field

[0001] The present invention relates to the technical field of earthquake resistance in civil engineering, and particularly relates to a method for calculating the seismic response of a group of closely spaced intersecting underground structures and an earthquake-resistant design process. Background Art

[0002] With the intensive development of urban underground space development, it is inevitable that underground projects will cross each other closely. Crossing forms such as cross-shaped and X-shaped are emerging continuously. For example, in the Hongzhong section between Line 2 and Line 4 of Wuhan Metro, there is a group of closely spaced overlapping tunnels with 4 tunnels of 2 lines, and the minimum net distance is only 1.3m ( Figure 1 ), which is much less than 1 times the tunnel diameter; another example is the cross-section of the intersection of Line 10 and Line 16 of Beijing Metro, the underground complex of Shanghai Hongqiao Hub and other actual engineering cases, where the structural spacing is generally less than 1 times the structural size (0.5D - 1D). These structures play an important role in the daily functions of the city. Therefore, it is very urgent to study the seismic performance of closely spaced underground crossing structures. Under certain conditions, the seismic performance of a single underground structure can meet its own seismic requirements. However, with the addition of newly built underground structures, more soil-structure interfaces change the propagation of seismic waves, thus changing the environment of the original single underground structure, and the smaller the spacing, the greater this change. Eventually, a complex interaction system of closely spaced underground crossing structures is formed, in which there are interactions between the original underground structure and the newly built underground structure, and between the underground structure and the soil mass.

[0003] The current deficiencies are mainly reflected in the following aspects:

[0004] 1) Insufficient basis for seismic design of intersection nodes: Currently, the design of underground intersection structures does not consider the influence of adjacent underground structures.

[0005] 2) Bottleneck in calculation efficiency: When jointly analyzing a certain underground four-story transfer station and a tunnel group in Guangzhou, the degrees of freedom of the ABAQUS model exceeded 5×10^6, and the single time history analysis took 240 hours, which could not meet the engineering iteration requirements.

[0006] 3) Distortion of three-dimensional wave field: The shaking table test by Japanese scholar Kawashima shows that the two-dimensional model will underestimate the stress concentration effect at the intersection node by 25%.

[0007] The 21st century is the century of urban underground space development and utilization. The urban underground space will surely be further developed and utilized on a large scale. The seismic performance of complex structures composed of closely spaced underground structures during an earthquake is crucial for the overall earthquake resistance and disaster prevention ability of the city. Its research is of great significance for improving the overall seismic performance and optimizing the urban disaster prevention and mitigation strategies. Summary of the Invention

[0008] In view of the deficiencies of the background technology, the technical problem to be solved by the present invention is to provide a calculation method for the seismic response of a group of closely spaced intersecting underground structures and an anti-seismic design process, which simplifies the complex interaction problem into a more mature seismic analysis problem of a single typical underground structure, realizes the seismic response analysis of a group of closely spaced intersecting underground structures under seismic action and a practical anti-seismic design process, and effectively solves the anti-seismic design problem of a large number of emerging groups of closely spaced underground intersecting structures at present.

[0009] To this end, the present invention is implemented by adopting the following technical solutions:

[0010] A calculation method for the seismic response of a group of closely spaced intersecting underground structures, characterized in that it includes the following steps:

[0011] Step 1: Establish a calculation model of soil - single typical underground structure and soil - group of closely spaced intersecting underground structures;

[0012] Step 2: Analyze the main influencing factors of the seismic response of soil - single typical underground structure and soil - group of closely spaced intersecting underground structures, and verify the rationality of the calculation models of soil - single typical underground structure and soil - group of closely spaced intersecting underground structures;

[0013] Step 3: Simplified calculation method for the seismic response of soil - group of closely spaced intersecting underground structures: Based on the verified calculation model, carry out numerical parameter analysis, and determine the value ranges of their respective influence factors by comparing with the seismic response of the corresponding soil - single typical underground structure.

[0014] Further, the said Step 1 includes the following sub - steps:

[0015] (1) Determination of the calculation range: According to the "Code for Seismic Design of Urban Rail Structure" and the specific dimensions of the subway depot, determine the corresponding calculation range;

[0016] (2) Establishment of the calculation model: Based on the actual structure dimensions and the soil calculation range, write the corresponding code program based on the parametric design language of the software to realize the establishment of the overall model;

[0017] (3) Mesh division and element type: The soil is adopted with 10 - node tetrahedral elements, and the above - ground and underground structures are discretized with structural elements;

[0018] (4) Constitutive model and calculation parameters: The soil adopts the Davidenkov equivalent linearization model to consider the nonlinear characteristics of the soil, and the structure adopts the plastic damage model of concrete;

[0019] (5) Contact treatment: Among them, the normal direction adopts hard connection to avoid intrusion, and the tangential friction adopts the Coulomb model;

[0020] (6) Boundary conditions: The lateral binding boundary is adopted to make the nodes at the same height of the model have the same horizontal displacement, so as to simulate the shear deformation of the soil mass during an earthquake;

[0021] (7) Damping setting: The Rayleigh damping model is adopted, and the Rayleigh damping coefficient is determined by calculating the system frequency;

[0022] (9) Dynamic time step: There should be at least 10 calculation steps within the time interval of the ground motion record;

[0023] (10) Ground motion input: The selected ground motion time history curve is input at the bottom of the model, and different input directions and their combinations are considered as required;

[0024] Finally, a calculation model is generated;

[0025] Furthermore, step 2 includes the following sub-steps:

[0026] (1) Based on the completed shaking table test, taking the completed test condition of double tunnels passing under a subway station as an example, by comparing and analyzing the test data and numerical calculation results, the rationality of the calculation models of soil - single typical underground structure and soil - closely spaced intersecting underground structure group is verified;

[0027] (2) Based on the numerical parameter analysis, the main influencing factors affecting the system are determined, including aspects of site soil, underground structure, and ground motion.

[0028] Furthermore, in the sub-step (1), the lateral calculation width of the calculation range is taken as 7 times the structure width, the longitudinal calculation length is equal to the structure length, and the vertical calculation depth depends on the bedrock surface depth of the formation where it is located.

[0029] Furthermore, in the sub-step (2), the software is BIM, and the code program includes global W_station, i.e., the width of the station (m), global L_station, i.e., the length of the station (m), global H_station, i.e., the height of the station (m), global D_tunnel, i.e., the diameter of the tunnel (m), global D_space, i.e., the net distance between the subway station and the tunnel (m), global E_structure, i.e., the elastic modulus of the structure (Pa), global Density_structure, i.e., the density of the structure (kg / m 3 )

[0030] Furthermore, in the sub-step (2), the aspect of site soil is the type of site soil, and the type of site soil includes medium-soft soil and medium-hard soil. The equivalent shear wave velocity of the medium-soft soil is less than or equal to 200 m / s, and the equivalent shear wave velocity of the medium-hard soil is greater than 200 m / s. The aspect of the underground structure includes the intersection angle φΘ 、Net structure spacing φ D 、Structural characteristic dimension φ L , where the ground motion aspects include ground motion type φ T and ground motion amplitude φ A .

[0031] Furthermore, the value range of the influence factors obtained from the calculation and analysis in step 3 is as follows in the table:

[0032] .

[0033] Furthermore, compare the seismic response results of the underground structure obtained by the simplified calculation method of the soil - closely - spaced underground structure group seismic response with the results of the shaking table test and the true three - dimensional time - history analysis to verify the rationality of the simplified method.

[0034] After adopting the above technical solutions, the present invention simplifies complex problems and transforms unknown problems into known problems, that is: calculate and analyze the seismic response law of complex underground cross - structures, determine the interaction influence factors under different working conditions, and use these influence factors to correct the seismic analysis method and seismic design process of the existing single typical underground structure, so as to establish the seismic response analysis method and seismic design process of complex closely - spaced underground structure groups.

[0035] The present invention also discloses a seismic design process based on the above - mentioned seismic response calculation method of the closely - spaced underground structure group, which is characterized by including the following steps:

[0036] Step 1: If the engineering requirement is a single underground structure, design according to the existing specifications and calculate and give the internal force and deformation of the structure;

[0037] Step 2: If the engineering requirement is a closely - spaced underground structure group, determine the influence factors of each factor based on the type of site soil, and take values for the intersection angle φ Θ 、Net structure spacing φ D 、Structural characteristic dimension φ L 、Ground motion type φ T and ground motion amplitude φ A and calculate and give the internal force and deformation of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention has the following drawings:

[0039] Figure 1 is a structural schematic diagram of 4 closely - spaced overlapping tunnel groups in the Hongzhong section of Wuhan Metro in the background technology;

[0040] Figure 2 is the overall flow chart of the present invention;

[0041] Figure 3 Schematic diagram of the calculation model established for the present invention, where (a) is the calculation model of a 4-hole tunnel at close range, (b) is the calculation model of a double tunnel passing under a subway station, and (c) is the intersection of tunnels (parallel up and down, 45 degrees, 90 degrees intersection);

[0042] Figure 4 Schematic diagram of the shaking table test of the close-range underground intersection structure group completed, where (a) is the schematic diagram of the shaking table test of a single tunnel and a double parallel tunnel, (b) is the schematic diagram of the shaking table test of parallel tunnels up and down, and (c) is the shaking table test of a double tunnel passing under a subway station;

[0043] Figure 5 Curve comparison diagram of the numerical calculation results and test data of the shaking table in the present invention, where (a) is the curve comparison diagram of the numerical calculation results and test data on the ground surface, (b) is the curve comparison diagram of the numerical calculation results and test data of the station, and (c) is the comparison of the numerical calculation results and test data under the condition of a double shield tunnel passing under a subway station;

[0044] Figure 6 Flow chart of the seismic design of the close-range intersection underground structure group in the present invention. Detailed implementation manners

[0045] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in combination with the attached drawings and preferred embodiments, details the specific implementation manners, structures, features and their effects according to the present invention as follows.

[0046] Referring to the above attached Figure 2-5 As shown, the method for calculating the seismic response of a close-range intersection underground structure group provided by the present invention is characterized in that it includes the following steps:

[0047] Step 1: Establish a calculation model of soil - a single typical underground structure and soil - a close-range intersection underground structure group; the said Step 1 includes the following sub-steps:

[0048] (1) Determination of the calculation range: Determine the corresponding calculation range according to the "Code for Seismic Design of Urban Rail Transit Structures" and the specific dimensions of the subway depot;

[0049] (2) Establishment of the calculation model: Based on the actual structural dimensions and the soil calculation range, write the corresponding code program based on the parametric design language of the software to realize the establishment of the overall model;

[0050] (3) Mesh division and element type: The soil adopts 10-node tetrahedral elements, and the above-ground and underground structures are discretized using structural elements;

[0051] (4) Constitutive model and calculation parameters: The Davidenkov equivalent linearization model is adopted for the soil to consider the nonlinear characteristics of the soil, and the plastic damage model of concrete is used for the structure;

[0052] (5) Contact treatment: Among them, the normal direction adopts hard contact to avoid intrusion, and the tangential friction adopts the Coulomb model;

[0053] (6) Boundary conditions: The lateral binding boundary is adopted to make the nodes at the same height of the model have the same horizontal displacement to simulate the shear deformation of the soil during an earthquake;

[0054] (7) Damping setting: The Rayleigh damping model is adopted, and the Rayleigh damping coefficient is determined by calculating the system frequency;

[0055] (8) Dynamic time step: There should be at least 10 calculation steps within the time interval of the ground motion record;

[0056] (9) Ground motion input: The selected ground motion time history curve is input at the bottom of the model, and different input directions and their combinations are considered as required;

[0057] (10) Finally, a calculation model is generated;

[0058] In the sub-step (1), the lateral calculation width of the calculation range is taken as 7 times the structure width, the longitudinal calculation length is equal to the structure length, and the vertical calculation depth depends on the bedrock surface depth of the location stratum;

[0059] In the sub-step (2), the software is BIM, and the code program includes global W_station which is the station width (m), global L_station which is the station length (m), global H_station which is the station height (m), global D_tunnel which is the tunnel diameter (m), global D_space which is the net distance between the subway station and the tunnel (m), global E_structure which is the structural elastic modulus (Pa), global Density_structure which is the structural density (kg / m 3 ), and the code program example is as follows:

[0060] global W_station = 80.0 ; Station width (m)

[0061] global L_station = 400.0 ; Station length (m)

[0062] global H_station = 12.0 ; Station height (m)

[0063] global D_tunnel = 12.0 ; tunnel diameter (m)

[0064] global D_space = 1.0 ; Clearance distance between subway station and tunnel (m)

[0065] global E_structure = 35e9 ; Structural elastic modulus (Pa)

[0066] global Density_structure = 2500 ; Structural density (kg / m3).

[0067] Step 2: Analyze the main influencing factors of the seismic response of soil-single typical underground structure and soil-closely intersecting underground structure groups, and verify the rationality of the calculation models of soil-single typical underground structure and soil-closely intersecting underground structure groups; Step 2 includes the following sub-steps:

[0068] (1) Based on the completed shaking table test, taking the completed double tunnel under the subway station test condition as an example, the rationality of the soil-single typical underground structure and soil-close-range cross-underground structure group calculation models was verified by comparing and analyzing the test data and numerical calculation results;

[0069] (2) Determine the main influencing factors of the system based on numerical parameter analysis, including site soil, underground structure, and seismic motion;

[0070] The site soil in the sub-step (2) is the site soil type, which includes medium soft soil and medium hard soil. The equivalent shear wave velocity of the medium soft soil is less than or equal to 200m / s, and the equivalent shear wave velocity of the medium hard soil is greater than 200m / s. The underground structure includes the intersection angle φ Θ 、Net structural spacing φ D 、Structural characteristic dimension φ L , the seismic aspects include seismic type φ T and the earthquake amplitude φ A .

[0071] Step 3: Simplified calculation method for the seismic response of soil-closely intersecting underground structures: Based on the verified calculation model, numerical parameter analysis is carried out. By comparing the seismic response of the corresponding soil-single typical underground structure, the value range of each influencing factor is determined;

[0072] The impact factor values calculated and analyzed in step 3 are as follows:

[0073] ;

[0074] The seismic response results of the underground structures obtained by the simplified calculation method of the soil mass - closely - spaced intersecting underground structure group are compared with the results of the shaking table test and the true three - dimensional time - history analysis to verify the rationality of the simplified method.

[0075] The present invention also provides an earthquake - resistant design process based on the above - mentioned calculation method for the seismic response of the closely - spaced intersecting underground structure group, which is characterized by the following steps:

[0076] Step 1: If the engineering requirement is a single underground structure, design it according to the existing specifications and calculate the internal forces and deformations of the structure.

[0077] Step 2: If the engineering requirement is a closely - spaced intersecting underground structure group, determine the influence factors of each factor based on the type of site soil, and take values for the intersection angle φ Θ 、the net spacing of the structures φ D 、the characteristic size of the structures φ L 、the type of ground motion φ T and the amplitude of the ground motion φ A to calculate the internal forces and deformations of the structures.

[0078] In the present invention, by establishing calculation models including soil mass - single typical underground structure and soil mass - closely - spaced intersecting underground structure group, the main influencing factors affecting the seismic response of the system are determined, and influence factors are recommended based on numerical parameter analysis. The complex interaction problem is simplified into the seismic analysis problem of a relatively mature single typical underground structure, realizing the seismic response analysis and practical earthquake - resistant design process of the closely - spaced intersecting underground structure group under earthquake action, and effectively solving the earthquake - resistant design problem of a large number of emerging closely - spaced underground structure intersecting structure groups at present.

[0079] The above - mentioned are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above - disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for calculating the seismic response of a group of closely spaced underground structures, characterized in that: The following steps are involved: Step 1: Establish calculation models of soil-single typical underground structure and soil-closely spaced intersecting underground structure groups; Step 2: Analyze the main influencing factors of the seismic response of soil-single typical underground structure and soil-closely intersecting underground structure groups, and verify the rationality of the calculation models of soil-single typical underground structure and soil-closely intersecting underground structure groups; Step 3: Simplified calculation method for the seismic response of soil-closely intersecting underground structures: Based on the verified calculation model, numerical parameter analysis is carried out. By comparing the seismic response of the corresponding soil-single typical underground structure, the value range of each influencing factor is determined; The step 2 includes the following sub-steps: Based on completed shaking table tests, taking the completed dual-tunnel underpass subway station test condition as an example, the rationality of the soil-single typical underground structure and soil-closely intersecting underground structure calculation models was verified by comparing and analyzing the test data and numerical calculation results. Determine the main influencing factors of the system based on numerical parameter analysis, including site soil, underground structure, and seismic motion; The respective influence factors in step 3 include the crossing angle φ Θ , the net structural spacing φ D , the structural characteristic size φ L , the type of ground motion φ T and the ground motion amplitude φ A .

2. The seismic response calculation method for the close-range cross underground structure group according to claim 1, characterized in that: The step 1 includes the following sub-steps: (1) Determination of calculation scope: Determine the corresponding calculation scope based on the "Code for Seismic Design of Urban Rail Structures" and the specific dimensions of the subway depot; (2) Establishment of the calculation model: Based on the actual structural dimensions and soil calculation range, the corresponding code program is written based on the parametric design language of the software to achieve the establishment of the overall model; (3) Meshing and element type: 10-node tetrahedron elements are used for soil, and structural elements are used for discretization of above-ground and underground structures; (4) Constitutive model and calculation parameters: The Davidenkov equivalent linearization model is used for soil to consider the nonlinear characteristics of the soil, and the plastic damage model of concrete is used for the structure; (5) Contact treatment: hard contact is used in the normal direction to avoid intrusion, and the Coulomb model is used for tangential friction; (6) Boundary conditions: Lateral binding boundaries are used to ensure that nodes at the same height in the model have the same horizontal displacement to simulate the shear deformation of the soil during an earthquake; (7) Damping setting: The Rayleigh damping model is used, and the Rayleigh damping coefficient is determined by the system frequency calculation; (8) Dynamic time step: There must be at least 10 calculation steps within the time interval of the ground motion recording; (9) Earthquake motion input: Input the selected earthquake motion time history curve at the bottom of the model, and consider different input directions and their combinations as required; (10) Finally, the computational model is generated.

3. The method for calculating the seismic response of the closely spaced cross - underground structure group according to claim 2, characterized in that: In the sub-step (1), the horizontal calculation width of the calculation range is 7 times the structure width, the longitudinal calculation length is equal to the structure length, and the vertical calculation depth depends on the depth of the bedrock surface of the local stratum.

4. The seismic response calculation method for the close-crossing underground structure group according to claim 2, characterized in that: In the sub-step (2), the software is BIM, and the code program includes global W_station, i.e., the width of the station (m), global L_station, i.e., the length of the station (m), global H_station, i.e., the height of the station (m), global D_tunnel, i.e., the diameter of the tunnel (m), global D_space, i.e., the net distance between the subway station and the tunnel (m), global E_structure, i.e., the elastic modulus of the structure (Pa), global Density_structure, i.e., the density of the structure (kg / m 3 ) 5. The seismic response calculation method for the close-range cross underground structure group according to claim 1, characterized in that: In the sub-step (2), the site soil aspect refers to the type of site soil, which includes medium-soft soil and medium-hard soil. The equivalent shear wave velocity of the medium-soft soil is less than or equal to 200 m / s, and the equivalent shear wave velocity of the medium-hard soil is greater than 200 m / s. The underground structure aspect includes the intersection angle φ Θ , the net spacing of the structure φ D , the characteristic dimension of the structure φ L . The ground motion aspect includes the type of ground motion φ T and the amplitude of the ground motion φ A .

6. The method for calculating the seismic response of a group of closely spaced cross - underground structures according to claim 1, wherein: The value range of the impact factor calculated and analyzed in step 3 is as follows: 。 7. The method for calculating the seismic response of a group of closely spaced cross-underground structures according to claim 6, characterized in that: The seismic response results of underground structures obtained by the simplified calculation method of the seismic response of soil-closely spaced intersecting underground structures are compared with the results of shaking table tests and real three-dimensional time history analysis to verify the rationality of the simplified method.

8. The seismic design process of the calculation method for the seismic response of the closely-spaced cross underground structure group according to any one of claims 1-7, characterized in that: The following steps are involved: Step 1: If the project requires a single underground structure, design it according to existing specifications and calculate the internal forces and deformations of the structure; Step 2: If the engineering requirement is a group of closely spaced underground structures with intersections, determine the influence factors of each factor based on the type of site soil, and determine the values of the intersection angle φ Θ , the net spacing between structures φ D , the characteristic dimension of the structure φ L , the type of ground motion φ T and the amplitude of ground motion φ A to calculate and obtain the internal forces and deformations of the structure.

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