A method for making a shaking table test model for an overlapping tunnel-group subway station

Abstract

The present invention provides a method for making a shaking table test model of an overlapping group-tunnel subway station, including similarity ratio determination, model surrounding rock material determination, model material determination, and model joint form and material determination: similarity ratio determination, according to the performance and parameters of the shaking table, including table size, bearing capacity, vibration degree of freedom, table input maximum acceleration and working frequency, determine the similarity between the model and the prototype; model surrounding rock material determination, mainly based on the similarity of physical indicators of model surrounding rock material and actual engineering surrounding rock material; model material determination, mainly based on the similarity of main physical indicators of model material and actual engineering structural material; model joint form and material determination, mainly based on the structural form and function of actual engineering joints, and the energy decay degree of the connection part under the action of earthquake motion. The present invention can make the test model and the actual project consistent to the maximum extent, and ensure the authenticity of the test effect.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering, and in particular relates to a method for manufacturing a shaking table test model of an overlapping tunnel-group subway station. Background Art

[0002] Due to the complexity and particularity of tunnel engineering, tunnel environment and earthquake action, it is impossible to conduct a large number of repetitive tests on prototype tunnels for the research on tunnel structure performance under the influence of earthquakes, and model tests can only be used. He Chuan, Zhang Jing and other scholars have studied the seismic response mechanism and damage mechanism of tunnel structures when passing through unfavorable geological conditions such as soil and rock strata and fault damage zones through shaking table model tests with different similarity ratios, and also proposed seismic isolation technology and measures. Xin Chunlei studied the seismic reduction measures of tunnel structures passing through fault fracture zones through model tests, mainly analyzing the differences in seismic response of lining structures under conditions such as the setting of seismic reduction layers, seismic reduction joints and the absence of any seismic reduction measures.

[0003] The use of shaking table model tests to simulate the dynamic response of subway stations under earthquakes and the way in which the structures are damaged and destroyed has gradually gained attention and reliance. However, the model making effect and accuracy in the test have a crucial impact on the test results. In the production of test models, in order to meet the limitations of the test equipment, the model making materials usually need to be determined through similar relationships. The determination of similar relationships and similar materials is the difficulty and focus of this type of test. Therefore, the research and development of test model design methods and test technologies is particularly important in similar test research processes. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for making a shaking table test model of an overlapping group-tunnel subway station, which can maximize the consistency between the test model and the actual project and ensure the authenticity of the test results.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] The embodiment of the present invention also provides a method for making a shaking table test model of an overlapping tunnel group subway station, including determining a similarity ratio, determining a model surrounding rock material, determining a model material, and determining a model joint form and material:

[0007] The similarity ratio is determined by determining the similarity between the model and the prototype based on the performance and parameters of the vibration table, including table size, load capacity, vibration degrees of freedom, table input maximum acceleration and operating frequency;

[0008] The model surrounding rock material is determined mainly based on the similarity of physical indicators between the model surrounding rock material and the actual engineering surrounding rock material, including elastic modulus, density, compressive strength and Poisson's ratio;

[0009] The model material is determined mainly based on the similarity of the main physical indicators of the model material and the actual engineering structure material, including material density, compressive strength and elastic modulus;

[0010] The model joint form and material are determined mainly based on the structural form and function of the actual engineering joint, and the degree of energy decay of the connection part under the action of seismic motion; in the description of seismic effect, it is represented by an acceleration time history curve; the acceleration time history curve is obtained through calculation and analysis.

[0011] Preferably, the similarity ratio is determined according to the Buckingham-π theorem, with the geometric dimensions, density, elastic modulus and inertial acceleration similarity ratio of the model as basic parameters, and the basic equation of the similarity relationship is:

[0012] S G / (S l ·S ρ )=S a (1)

[0013] Where S G , S l and S ρ are the shear modulus, geometric dimensions and density similarity ratio of the model, S a is the inertial acceleration similarity ratio;

[0014] The geometric dimensions and density similarity ratio are based on the performance and parameters of the vibration table, including table size, load capacity, vibration degree of freedom, maximum table input acceleration and operating frequency; the elastic modulus and inertial acceleration similarity ratio are obtained by converting the geometric dimensions and density similarity ratio through formula (1).

[0015] As a preferred method, the model surrounding rock material is determined, and foamed concrete is selected as the surrounding rock model material, which is analogous to the surrounding rock around the actual engineering tunnel; the foamed concrete mix ratio adopts cement: water: foam = 9kg: 4.6kg: 16L; the physical and mechanical properties of the foamed concrete are determined by indoor tests, wherein the elastic modulus is determined by making a 150mm×

[0016] The compressive strength of the prism test block with a side length of 150mm×300mm was tested by making a cubic test block with a side length of 150mm using a pressure testing machine.

[0017] As a preferred model material, a mixture of gypsum and diatomaceous earth is selected as the model material, analogous to the concrete in the actual engineering structure; the gypsum and diatomaceous earth mixture ratio adopts water: gypsum: diatomaceous earth

[0018] =1.6kg:1kg:0.1kg; By casting a standard specimen of Φ50×100mm, the elastic modulus is tested using a pressure testing machine;

[0019] Galvanized steel wire was selected as the model skeleton material, analogous to the steel bars in the actual engineering structure; the cross-sectional reinforcement ratio of the test model tunnel structure was determined according to the equal strength principle, and the steel bars inside the actual engineering tunnel structure were converted into the corresponding steel wire mesh, and the formula is as follows:

[0020]

[0021] Among them, A ps , f py are the cross-sectional steel bar area and strength of the prototype structure; A pc , f pc are the cross-sectional concrete area and strength of the prototype structure; A ms , f my are the cross-sectional steel bar area and strength of the model structure; A mc , f mc are the cross-sectional concrete area and strength of the model structure respectively.

[0022] Preferably, the joint form and material of the model are determined by establishing different surrounding rock, tunnel structure and joint numerical simulation analysis models:

[0023] (1) Numerical simulation model of actual tunnel engineering, using the material properties of surrounding rock, tunnel structure and joints used in actual engineering;

[0024] (2) A numerical simulation model of the physical test model, using the aforementioned physical test model simulation materials, foamed concrete, gypsum and diatomaceous earth mixture, and the undetermined joint filling material;

[0025] During the numerical simulation analysis, the properties of the joint filling material are adjusted, and the energy decay patterns and degrees of the connection parts of the two different numerical simulation models under the action of seismic motion are compared until the seismic effects of the joints in the two different numerical simulation models are consistent, and the properties of the joint filling material can be determined.

[0026] Preferably, the model making steps are as follows:

[0027] (1) Determine the similarity ratio based on the performance of the vibration table and the test simulation range;

[0028] (2) Compare and select model materials and determine material ratio;

[0029] (3) Cut the foam according to the drawing and make the inner mold template of the test model tunnel structure;

[0030] (4) Cut wooden boards according to the drawings and make the outer formwork template of the test model tunnel structure;

[0031] (5) Wire mesh tied to the test model tunnel structure skeleton;

[0032] (6) Assembling the test model tunnel structure template;

[0033] (7) preparing a mixture of gypsum and diatomaceous earth according to the ratio determined by the test model material selection;

[0034] (8) Integral casting test model tunnel lining;

[0035] (9) Dismantle the inner and outer formwork of the test model tunnel lining;

[0036] (10) Indoor dehumidification curing test model tunnel lining for 15 days;

[0037] (11) Assembling the various components of the test model tunnel lining to form an integral model tunnel;

[0038] (12) Making external simulated surrounding rock templates for the test model tunnel;

[0039] (13) pouring foamed concrete on the outside of the test model tunnel to form simulated surrounding rock of the test model tunnel;

[0040] (14) Overall maintenance for 28 days;

[0041] (15) Remove the external formwork of the test model tunnel to simulate the surrounding rock and complete the production of the test model.

[0042] The present invention has the following beneficial effects:

[0043] The invention provides a method for making a shaking table test model of an overlapping tunnel subway station. Compared with the prior art, the invention has the following beneficial effects:

[0044] (1) The present invention provides a complete set of methods for making a shaking table test model for simulating earthquake effects on tunnel engineering. This method can maximize the consistency between the test model and the actual engineering, thereby ensuring the authenticity of the test results.

[0045] (2) The test results obtained by the method provided by the present invention can effectively guide the design and construction of actual projects.

[0046] (3) The method for selecting structural joint filling materials provided by the present invention can not only guide the design of such experimental schemes and the construction of models, but can also be applied to actual projects to further explore the construction technology for forming such structural joints. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of the present invention.

[0048] Figure 1 The figures are comparison diagrams of the numerical simulation analysis results of the joint material selection in the embodiment of the present invention, wherein (a) is a comparison diagram of the acceleration time history curve, (b) is a comparison diagram of the acceleration spectrum curve, and (c) is a comparison diagram of the spectrum amplification factor;

[0049] Figure 2 (a) perspective view, (b) cross-sectional view, and (c) longitudinal view of a physical test model in an embodiment of the present invention;

[0050] Figure 3 The flow chart of the physical test model in the embodiment of the present invention is shown in FIG.

[0051] Description of reference numerals:

[0052] 1. Tunnel; 2. Surrounding rock; 3. Tunnel structure; 4. Communication passage; 5. Joint. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] This embodiment provides a method for making a model for a subway station shaking table model test, including determining a similarity ratio, determining a model surrounding rock material, determining a model material, and determining a model joint form and material.

[0055] 1. Determination of similarity ratio. In this embodiment, according to the Buckingham-π theorem, the geometric size, density, elastic modulus and inertial acceleration similarity ratio of the model are used as basic parameters, and the basic equation of the similarity relationship is:

[0056] S G / (S l ·S ρ )=S a (1)

[0057] Where S G , S l and S ρ are the shear modulus, geometric dimensions and density similarity ratio of the model, S a is the inertial acceleration similarity ratio.

[0058] The geometric dimensions and density similarity ratio are based on the performance and parameters of the vibration table, including table size, load capacity, vibration degree of freedom, maximum table input acceleration and operating frequency; the elastic modulus and inertial acceleration similarity ratio are obtained by converting the geometric dimensions and density similarity ratio through formula (1).

[0059] 2. The model surrounding rock material is determined based on the elastic modulus, density, compressive strength and Poisson's ratio of the model surrounding rock material and the actual engineering surrounding rock material.

[0060] In this embodiment, foamed concrete is selected as the model material of surrounding rock 2, analogous to the surrounding rock around the actual engineering tunnel. The foamed concrete mix ratio adopts cement: water: foam = 9kg: 4.6kg: 16L. The physical and mechanical properties of foamed concrete are determined by indoor tests, where the elastic modulus is determined by making a prism test block with a side length of 150mm×150mm×300mm, and the compressive strength is determined by making a cubic test block with a side length of 150mm, and tested by a pressure test machine, referring to the "Standard for Test Methods for Physical and Mechanical Properties of Concrete" (GB / T 50081-2019).

[0061] 3. The model material is determined based on the material density, elastic modulus and compressive strength of the model material and the actual engineering structure material.

[0062] (1) In this embodiment, a mixture of gypsum and diatomite is selected as a model material, analogous to concrete in actual engineering structures. The proportion of gypsum and diatomite mixture is water: gypsum: diatomite = 1.6kg: 1kg: 0.1kg. The elastic modulus is tested by pouring a standard specimen of Φ50×100mm using a pressure testing machine. Refer to "Determination of Mechanical Properties of Building Gypsum" (GB / T 17669.3-1999).

[0063] (2) In this embodiment, galvanized steel wire is selected as the model skeleton material, analogous to the steel bars in the actual engineering structure. The cross-sectional reinforcement ratio of the test model tunnel structure 3 is determined according to the equal strength principle, and the steel bars inside the actual engineering tunnel structure are converted into corresponding steel wire meshes, and the formula is as follows:

[0064]

[0065] Among them, A ps , f py are the cross-sectional steel bar area and strength of the prototype structure; A pc , f pc are the cross-sectional concrete area and strength of the prototype structure; A ms , f my are the cross-sectional steel bar area and strength of the model structure; A mc , f mc are the cross-sectional concrete area and strength of the model structure respectively.

[0066] 4. The material of the model joint is determined according to the structural form and function of the actual engineering joint, as well as the degree of energy decay of the connection part under the action of earthquake motion. In the description of earthquake effect, it is represented by the acceleration time history curve; the acceleration time history curve is obtained through calculation and analysis. The acceleration time history curve needs to be obtained through calculation and analysis.

[0067] Normally, there are two main connection modes between the subway station connecting channel and the main tunnel. One is rigid connection, which can be simulated by using high-strength adhesives such as epoxy resin, assuming that the nodes of the connection part do not undergo relative displacement; the other is flexible connection, which assumes that the nodes of the connection part can undergo a certain relative displacement.

[0068] In this embodiment, numerical simulation analysis models of different surrounding rocks, tunnel structures and joints are established:

[0069] (1) Numerical simulation model of actual tunnel engineering, using the material properties of surrounding rock, tunnel structure and joints used in actual engineering;

[0070] (2) The numerical simulation model of the physical test model adopts the aforementioned physical test model simulation materials foamed concrete, gypsum + diatomaceous earth, and the undetermined joint filling material.

[0071] During the numerical simulation analysis, the properties of the joint filling material are adjusted, and the energy decay patterns and degrees of the connection parts of the two different numerical simulation models under the action of seismic motion are compared until the seismic effects of the joints in the two different numerical simulation models are consistent, and the properties of the joint filling material can be determined.

[0072] Table 1 Numerical simulation analysis parameters

[0073]

[0074] In this embodiment, the connecting channel 4 and the tunnel 1 are flexibly connected, and the connection mode of the joint 5 is a flexible connection. Through numerical simulation analysis, silicone rubber is used to simulate the joint. The specific parameters are as follows: silicone rubber type 703, viscosity 5000Pa.s, operating temperature range -60~150℃, tensile strength 1.2Mpa, elongation 250%, Shore hardness 20-30A, and shear strength 1.1Mpa.

[0075] The physical test model making process of this embodiment is as follows:

[0076] (1) Determine the similarity ratio based on the vibration table performance and test simulation range.

[0077] (2) Compare and select model materials and determine the material ratio.

[0078] (3) Cut the foam according to the drawing and make the inner mold template of the test model tunnel structure 3.

[0079] (4) Cut wooden boards according to the drawings and make the outer formwork template of the test model tunnel structure 3.

[0080] (5) Test model tunnel structure 3 skeleton tied with wire mesh.

[0081] (6) Assemble the test model tunnel structure 3 template.

[0082] (7) Prepare a gypsum + diatomaceous earth mixture according to the ratio determined by the test model material selection.

[0083] (8) Integral casting of test model tunnel lining.

[0084] (9) Remove the inner and outer formwork of the test model tunnel lining.

[0085] (10) Indoor dehumidification maintenance test model tunnel lining for 15 days.

[0086] (11) Assemble the various components of the test model tunnel lining to form an overall model tunnel 1.

[0087] (12) Produce a template for simulating the surrounding rock 2 outside the test model tunnel 1.

[0088] (13) Pouring foamed concrete on the outside of the test model tunnel to form simulated surrounding rock of the test model tunnel.

[0089] (14) Overall maintenance for 28 days.

[0090] (15) Remove the external formwork of the test model tunnel to simulate the surrounding rock and complete the production of the test model.

[0091] The present invention is currently aimed at solving the problem of test model design and production in the vibration table test of subway stations. Through the inventor's systematic research on its working principle, the problem of similarity between the test model and the actual project is solved, and the test model is highly similar to the tunnel structure in the actual project. In fact, the basic idea behind the present invention can also be used in similar work and device development in other fields.

[0092] It can be seen from the above technical solutions that the method for making a shaking table test model of an overlapping group-tunnel subway station provided in this embodiment is a complete method for making a shaking table test model for simulating earthquake effects on tunnel engineering. This method can maximize the consistency between the test model and the actual engineering and ensure the authenticity of the test results. The test results obtained by the method provided in this embodiment can effectively guide the design and construction of actual engineering. The method for selecting structural joint filling materials provided in this embodiment can not only guide the design of such test schemes and the construction of models, but can also be applied to actual engineering to further explore the construction technology for forming such structural joints.

[0093] The above embodiments of the present invention are described in detail through examples, but the contents described are only exemplary embodiments of the embodiments of the present invention and cannot be considered to limit the scope of implementation of the embodiments of the present invention. The protection scope of the embodiments of the present invention is defined by the claims. Anyone who utilizes the technical solutions described in the embodiments of the present invention, or who, inspired by the technical solutions of the embodiments of the present invention, designs similar technical solutions within the essence and protection scope of the embodiments of the present invention to achieve the above technical effects, or who makes equal changes and improvements to the scope of application, shall still fall within the scope of protection covered by the patent of the embodiments of the present invention.

Claims

1. A method for making a shaking table test model of an overlapping tunnel subway station, characterized in that: Including similarity ratio determination, model surrounding rock material determination, model material determination, and model joint form and material determination: The similarity ratio is determined by determining the similarity between the model and the prototype based on the performance and parameters of the vibration table, including table size, load capacity, vibration degrees of freedom, table input maximum acceleration and operating frequency; The model surrounding rock material is determined mainly based on the similarity of physical indicators between the model surrounding rock material and the actual engineering surrounding rock material, including elastic modulus, density, compressive strength and Poisson's ratio; The model material is determined mainly based on the similarity of the main physical indicators of the model material and the actual engineering structure material, including material density, compressive strength and elastic modulus; The model joint form and material are determined mainly based on the structural form and function of the actual engineering joint, and the energy decay degree of the connection part under the action of earthquake motion. The energy decay degree is represented by an acceleration time history curve in the description of earthquake effect; the acceleration time history curve is obtained by calculation and analysis; The joint form and material of the model are determined by establishing different surrounding rock, tunnel structure and joint numerical simulation analysis models: (1) Numerical simulation model of actual tunnel engineering, using the material properties of surrounding rock, tunnel structure and joints used in actual engineering; (2) The numerical simulation model of the test model uses the model surrounding rock material and model material determined above, as well as the undetermined joint filling material; During the numerical simulation analysis, the properties of the joint filling material are adjusted, and the energy decay law and degree of the connection parts of the two different numerical simulation models of the actual tunnel project and the test model under the action of seismic motion are compared until the seismic effect of the joints in the two different numerical simulation models is consistent, and the properties of the joint filling material can be determined.

2. The method for making a shaking table test model of an overlapping tunnel subway station according to claim 1 is characterized in that: The similarity ratio is determined according to the Buckingham-π theorem, with the geometric size, density, elastic modulus and inertial acceleration similarity ratio of the model as basic parameters, and the basic equation of the similarity relationship is: （1） in are the shear modulus, geometric dimensions and density similarity ratio of the model, is the inertial acceleration similarity ratio; The geometric dimensions and density similarity ratio are based on the performance and parameters of the vibration table, including table size, load capacity, vibration degree of freedom, maximum table input acceleration and operating frequency; the elastic modulus and inertial acceleration similarity ratio are obtained by converting the geometric dimensions and density similarity ratio through formula (1).

3. The method for making a shaking table test model of an overlapping tunnel subway station according to claim 2 is characterized in that: The model surrounding rock material is determined, and foamed concrete is selected as the surrounding rock model material, which is analogous to the surrounding rock around the actual engineering tunnel; the foamed concrete mix ratio adopts cement: water: foam = 9kg: 4.6kg: 16L; the physical and mechanical properties of the foamed concrete are determined through indoor tests, wherein the elastic modulus is determined by making a prism test block with a side length of 150mm×150mm×300mm, and the compressive strength is determined by making a cubic test block with a side length of 150mm, and tested by a pressure testing machine.

4. The method for making a shaking table test model of an overlapping tunnel subway station according to claim 3 is characterized in that: The model material is determined by selecting a mixture of gypsum and diatomaceous earth as the model material, analogous to the concrete in the actual engineering structure; the gypsum and diatomaceous earth mixture ratio is water: gypsum: diatomaceous earth = 1.6kg: 1kg: 0.1kg; by casting a standard specimen of Φ50×100mm, the elastic modulus is tested using a pressure testing machine; Galvanized steel wire was selected as the model skeleton material, analogous to the steel bars in the actual engineering structure; the cross-sectional reinforcement ratio of the test model tunnel structure was determined according to the equal strength principle, and the steel bars inside the actual engineering tunnel structure were converted into the corresponding steel wire mesh, and the formula is as follows: ； in, are the cross-sectional reinforcement area and strength of the prototype structure, respectively; are the cross-sectional concrete area and strength of the prototype structure, respectively; are the cross-sectional reinforcement area and strength of the model structure respectively; are the cross-sectional concrete area and strength of the model structure respectively.

5. The method for making a shaking table test model of an overlapping tunnel subway station according to claim 1, characterized in that: The model making steps are as follows: (1) Determine the similarity ratio based on the vibration table performance and test simulation range; (2) Compare and select model materials and determine material ratio; (3) Cut the foam according to the drawing and make the inner mold template of the test model tunnel structure; (4) Cut wooden boards according to the drawings and make the outer formwork of the test model tunnel structure; (5) Tie wire mesh to the test model tunnel structure frame; (6) Assembling the test model tunnel structure template; (7) Prepare a mixture of gypsum and diatomaceous earth according to the ratio determined by the test model material selection; (8) Integral casting test model tunnel lining; (9) Dismantle the inner and outer formwork of the test model tunnel lining; (10) Indoor dehumidification curing test model tunnel lining for 15 days; (11) Assembling the various components of the test model tunnel lining to form an integral model tunnel; (12) Make a template for simulating surrounding rock outside the test model tunnel; (13) Pouring foamed concrete on the outside of the test model tunnel to form simulated surrounding rock of the test model tunnel; (14) Overall maintenance for 28 days; (15) Remove the external formwork of the test model tunnel to simulate the surrounding rock and complete the production of the test model.

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