Low-frequency vibration and noise reduction structure system for subway tunnel and design method

Abstract

The invention discloses a low-frequency vibration attenuation and noise reduction structure system for a subway tunnel and a design method, macromolecule geopolymer concrete adopted by the low-frequency vibration attenuation and noise reduction structure system for the subway tunnel is a simulated phonon crystal concrete ternary structure body, and the structure system comprises a vibration attenuation and isolation foundation ballast bed composite structure and a sound insulation and vibration attenuation composite structure; the vibration reduction and isolation foundation and ballast bed composite structure comprises a vibration isolation wall, a modified soil layer, vibration reduction piles, a foundation and a ballast bed. The vibration isolation wall is inserted into the foundation to form two side boundaries, the modified soil layer is arranged at the top of a groove formed by the vibration isolation wall and the foundation, the vibration reduction pile sequentially penetrates through the modified soil layer and the foundation from top to bottom, the bottom of the vibration reduction pile is flush with the bottom of the vibration isolation wall, and the track bed is arranged at the top of the modified soil layer. The sound insulation and vibration reduction composite structure comprises a sound insulation barrier layer and a vibration reduction wall. According to the low-frequency vibration and noise reduction structural system for the subway tunnel, high-molecular geopolymer concrete which is excellent in physical and chemical performance, stable in long-acting performance, low in carbon and environmentally friendly is adopted as a vibration reduction structural material, optimized low-frequency vibration and noise reduction and long-acting operation and maintenance of subway engineering can be achieved, and the low-frequency vibration and noise reduction structural system has the advantages of being simple in process, low in later-period maintenance cost, ecological, environmentally friendly and the like.

Description

Technical Field

[0001] The present invention relates to the field of subway tunnel engineering, and in particular to a low-frequency vibration and noise reduction structural system for subway tunnels and an optimization design method. Background Art

[0002] Urban rail transit projects are key livelihood projects in my country's transportation sector. With the continuous expansion of modern urban scale and the significant increase in population density, the available ground land resources are becoming increasingly tight, resulting in the rapid and effective development of subway projects underground in cities. Subways have the advantages of large carrying capacity, high speed, punctual operation, safety and reliability, and play an irreplaceable role in the construction of urban three-dimensional space transportation systems and the alleviation of urban traffic congestion. However, during the construction process, subways will inevitably overlap or be close to ground building structures in the vertical direction, which leads to more serious vibration and noise effects during subway operation, which brings about a series of problems that need to be solved urgently.

[0003] First, the vibration generated during subway operation is gradually transmitted to the upper ground building structure through the surrounding medium soil layer, thereby inducing secondary vibration of the building structure, which in turn leads to uneven settlement of the building foundation, fatigue cracking damage or even collapse, seriously shortening the functional accuracy and service life of precision instruments and equipment; secondly, the long-term vibration of the subway causes the cumulative deformation of the surrounding shallow buried soil layer to exceed the standard, resulting in leakage in the tunnel lining structure in the later stage. Over time, water and sand gushing occurs, resulting in large-scale settlement of the ground to varying degrees and deformation and damage of the tunnel structure; thirdly, the long-term and repeated low-frequency vibration of the subway The frequency is highly coincident with the natural frequency of the main organs of the human body, which will cause irreversible and serious damage to the physical and mental health of residents; then, the existing subway roadbeds and sleepers are mostly made of ordinary cement concrete, which belongs to a rigid structural system and has no attenuation effect on vibration response. In addition, cement produces a large amount of environmental pollution and greenhouse gases during the preparation, transportation and construction process, which is not in line with the concept of sustainable development of ecological environment protection in the transportation field; finally, the viscoelastic damping materials, fasteners and floating plates in the traditional subway vibration and noise reduction measures have more or less problems such as poor integrity, easy aging, poor serviceability and high construction cost.

[0004] In view of this, it is necessary to provide a new low-frequency vibration and noise reduction structural system for subway tunnels and a construction method thereof to solve or at least improve the above-mentioned technical defects. Summary of the invention

[0005] The main purpose of the present invention is to provide a low-frequency vibration and noise reduction structural system for subway tunnels and a design method thereof, aiming to solve the technical problems of poor vibration and noise reduction effects and environmental pollution in the prior art subway tunnels.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, the present invention provides a low-frequency vibration reduction and noise reduction structural system for a subway tunnel, comprising a vibration reduction and vibration isolation foundation ballast composite structure and a sound insulation and vibration reduction composite structure; the vibration reduction and vibration isolation foundation ballast composite structure comprises a vibration isolation wall, a modified soil layer, a vibration reduction pile, a foundation and a ballast, the vibration isolation wall is inserted into the interior of the foundation to form two side boundaries, the modified soil layer is arranged at the top of the groove formed by the vibration isolation wall and the foundation, the vibration reduction pile passes through the modified soil layer and the foundation in sequence from top to bottom, and the bottom of the vibration reduction pile is arranged flush with the bottom of the vibration isolation wall, and the ballast is arranged on the top of the modified soil layer; the sound insulation and vibration reduction composite structure comprises a sound insulation barrier layer and a vibration reduction wall, and the vibration reduction wall is arranged on the upper surface of the sound insulation barrier layer.

[0007] The vibration-damping pile comprises a modified rubber coating, a support pipe and a mixing pile. The modified rubber coating is sleeved on the outer surface of the support pipe, and the mixing pile is arranged inside the support pipe and is formed by mixing concrete. The modified soil layer is formed by injecting grouting cementitious materials into the foundation surface soil layer and mixing them.

[0008] The vibration isolation wall, vibration reduction pile, roadbed and polymer concrete vibration reduction wall are all made of concrete materials; the concrete materials include the following components by weight: 642-875 parts of granulated blast furnace slag powder, 275-375 parts of fly ash, 92-125 parts of silica fume, 1326-1807 parts of coarse aggregate, 1014-1382 parts of fine aggregate, 2-6 parts of modified expanded polystyrene polymer particles, 404-550 parts of alkali activator, 25-34 parts of high-performance water reducing agent, and 242-330 parts of mixing water. The ternary structure of pseudo-phononic crystal concrete is formed by mixing in this way.

[0009] The coarse aggregate has a particle size of 15 to 25 mm and is a combination of one or more of basalt, granite, and limestone, with basalt being preferred; the fine aggregate has a fineness modulus of 1.5 to 2.5 and is a combination of one or more of river sand, machine-made sand, and recycled concrete fine aggregate.

[0010] The polystyrene polymer particles are prepared from expanded polystyrene polymer particles and a modifier; the particle size of the expanded polystyrene polymer particles is 1.5-3.0 mm; the modifier is added in an amount of 1%-3%, and is one or more combinations of triethanolamine, polyvinyl alcohol, and guar gum ether.

[0011] The alkali activator is one or more combinations of alkali metal hydroxides, alkali silicates, alkali carbonates, and alkali sulfates, wherein a composite alkali activator of alkali metal hydroxides and alkali silicates is preferred; the high-performance water reducer is a high-performance polycarboxylic acid-based water reducer.

[0012] In the design method of the low-frequency vibration and noise reduction structural system for the subway tunnel, the polymer geopolymer concrete is a ternary structure of phononic crystal concrete, and each parameter satisfies the following conditions:

[0013]

[0014]

[0015] Among them, H f is the effective vibration reduction frequency bandwidth, is the filling rate of the ternary structure of pseudophononic crystal concrete;

[0016] n is the number of scatterers in the pseudophononic crystal aggregate, r i is the radius of the unit cell scatterer, a is the lattice constant of the pseudophononic crystal;

[0017] Therefore, each performance parameter directly affects the strength, vibration reduction performance and band gap distribution of concrete; therefore, it is necessary to first control the filling rate of high molecular weight geopolymer concrete. Then control the size or gradation of each unit cell to achieve the best coupling between lattice constant and filling rate. Therefore, it is recommended that the maximum particle size of the unit cell scatterer is r i Less than 0.03m, so as to control the grading of aggregate.

[0018] The construction method of the above-mentioned vibration reduction and noise reduction structural system for subway tunnels comprises the following steps:

[0019] Step 1: Measure and lay out, initially level the site, inject grouting materials into the soil within a certain depth range below the surface of the foundation and mix it thoroughly with a mixer. Stop mixing after the mixed soil has solidified, and use a press to compact and level the solidified surface soil of the foundation to ensure that the overall height difference of the soil layer on the foundation surface is no more than 10mm;

[0020] Step 2: Excavate the earth and stone for pre-embedded vibration isolation walls and vibration reduction piles according to the direction, burial depth and location of the vibration isolation walls and vibration reduction piles specified in the design drawings;

[0021] Step 3: Wrap and fix the modified rubber coating layer on the outer surface of the support pipe, hoist the prefabricated vibration isolation wall and support pipe and place them in the corresponding positions after excavation, and pour the prepared concrete material into the support pipe to form vibration reduction piles; hoist the prefabricated integrated ballast and place it on the corresponding position of the foundation surface to form a vibration reduction and vibration isolation foundation ballast composite structure;

[0022] Step 4: According to the location of the vibration isolation wall, hoist the sound insulation barrier layer and place it on the corresponding position of the foundation surface, then hoist the vibration reduction wall and place it close to the top of the sound insulation barrier layer to form a sound insulation and vibration reduction composite structure.

[0023] In this way, an overall structure for vibration reduction and noise reduction is formed by vibration isolation walls, vibration reduction piles, modified soil layers and sound insulation barriers, thus realizing an efficient vibration reduction and noise reduction system for subway rail transit.

[0024] In the above scheme, the low-frequency vibration reduction and noise reduction structural system for subway tunnels includes a vibration reduction and vibration isolation foundation and ballast composite structure and a sound insulation and vibration reduction composite structure; the vibration reduction and vibration isolation foundation and ballast composite structure includes a vibration isolation wall, a modified soil layer, a vibration reduction pile, a foundation and a ballast; the sound insulation and vibration reduction composite structure includes a sound insulation barrier layer and a vibration reduction wall. This low-frequency vibration reduction and noise reduction structural system for subway tunnels uses materials with excellent physical and chemical properties, long-term stable performance, and low carbon and environmental protection as vibration reduction structural materials and composite acoustic metamaterials as sound insulation and noise reduction structures, which can achieve high-efficiency low-frequency vibration reduction and noise reduction and long-term operation and maintainability of subway projects, and has the advantages of simple process, low later maintenance costs, and ecological and environmental protection.

[0025] The present invention mainly has the following beneficial effects:

[0026] 1. The present invention adopts concrete materials, wherein the elastic constants and mass densities of coarse aggregate, modified expanded polystyrene polymer particles and geopolymer mortar are significantly different. During the preparation process, the modified expanded polystyrene polymer particles can be suspended and wrapped on the surface of the coarse aggregate scatterer to form a unit cell, and embedded in the geopolymer mortar matrix to form a three-component local resonance type phononic crystal structure, which can generate a broadband low-frequency band gap, which can effectively inhibit and block the propagation of low-frequency elastic waves generated by vibration during subway operation, thereby significantly reducing the impact of low-frequency vibration. Since the phononic crystal ternary structure of a single unit cell has only one vibration-damping band gap, and the pseudo-phononic crystal is composed of multiple units, the number of vibration-damping band gaps is equivalent to the number of pseudo-phononic crystal heavy units, and an optimized design is required to achieve efficient vibration reduction. The effect of the optimized design depends on the lattice constant and filling rate of the ternary structure. In addition, the sound insulation barrier layer composed of a double-layer sound insulation board and an acoustic metamaterial film can couple the resonance effect of the acoustic metamaterial film and the Helmholtz resonance effect of the internal cavity of the sound insulation board to achieve efficient blocking of the low-frequency vibration noise of the subway.

[0027] 2. The present invention adopts vibration isolation walls, modified soil layers and vibration reduction piles as vibration reduction and isolation foundation structures. On the one hand, it can effectively cut off the elastic wave propagation path of subway vibration transmitted through the soil, thereby reducing the adverse effects of subway vibration. On the other hand, it significantly improves the stress characteristics of the foundation, enhances the bearing capacity of the foundation, and weakens the fatigue damage of the foundation under the long-term cyclic dynamic load of the subway. It can prevent the subway track bearing structure from experiencing different degrees of uneven settlement, achieve uneven control of the subway track, reduce wheel-rail impact noise, and alleviate rail wear and damage.

[0028] 3. The present invention adopts geopolymer as the base cementitious material for preparing concrete. As a new type of solid waste-based green cementitious material, geopolymer has the advantages of excellent mechanical properties, early strength and fast hardening, good long-term durability, and strong resistance to chemical ion corrosion. In addition, the raw materials for preparing geopolymer are mostly bulk industrial solid waste containing silicon and aluminum mineral components. While being able to effectively improve the resource utilization rate of industrial solid waste, it further achieves the ecological sustainable development goals of low-carbon emission reduction, reduced environmental pollution, and reduced greenhouse gas emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0030] Figure 1 It is a cross-sectional schematic diagram of a vibration reduction and noise reduction structural system for a subway tunnel according to an example of the present invention;

[0031] Figure 2 It is a three-dimensional structural diagram of a vibration reduction and noise reduction structural system for a subway tunnel according to an example of the present invention;

[0032] Figure 3 It is the structural schematic diagram of the vibration reduction pile;

[0033] Figure 4 Aggregate gradation curves in concrete of different schemes in Examples 1 to 5;

[0034] Figure 5 is the energy band structure diagram of the concrete obtained in Example 1;

[0035] Figure 6 is the energy band structure diagram of the concrete obtained in Example 2;

[0036] Figure 7 is the energy band structure diagram of the concrete obtained in Example 3;

[0037] Figure 8 is the energy band structure diagram of the concrete obtained in Example 4;

[0038] Fig. 9 This is the energy band structure diagram of the concrete obtained in Example 5.

[0039] Explanation of the accompanying figures: 1. Vibration isolation wall; 2. Modified soil layer; 3. Vibration reduction piles; 4. Foundation; 5. Roadbed; 6. Sound insulation barrier layer; 7. Vibration reduction wall; 8. Modified rubber coating layer; 9. Support pipe; 10. Mixing piles.

[0040] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0043] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0044] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0046] See also Figure 1-Figure 2The present invention provides a low-frequency vibration reduction and noise reduction structural system for subway tunnels, including a vibration reduction and vibration isolation foundation ballast composite structure and a sound insulation and vibration reduction composite structure; the vibration reduction and vibration isolation foundation ballast composite structure includes a vibration isolation wall 1, a modified soil layer 2, a vibration reduction pile 3, a foundation 4 and a ballast 5, and the materials of the above components or structures are all polymer geopolymer concrete. The vibration isolation wall 1 is inserted into the foundation 4 to form the boundaries on both sides, the modified soil layer 2 is arranged at the top of the groove formed by the vibration isolation wall 1 and the foundation 4, the vibration reduction pile 3 passes through the modified soil layer 2 and the foundation 4 from top to bottom, and the bottom of the vibration reduction pile 3 is arranged flush with the bottom of the vibration isolation wall 1, and the ballast 5 is arranged on the top of the modified soil layer 2; the sound insulation and vibration reduction composite structure includes a sound insulation barrier layer 6 and a vibration reduction wall 7, and the vibration reduction wall 7 is arranged on the upper surface of the sound insulation barrier layer 6.

[0047] The above-mentioned vibration isolation wall 1, vibration reduction piles 3, roadbed 5, and vibration reduction wall 7 are all made of high molecular geopolymer concrete material. As a new type of solid waste-based green cementitious material, geopolymer has the advantages of excellent mechanical properties, early strength and rapid hardening, good long-term durability, and strong resistance to chemical ion corrosion. In addition, the raw materials for preparing geopolymers are mostly bulk industrial solid waste containing silicon and aluminum mineral components. While being able to effectively improve the resource utilization rate of industrial solid waste, it further achieves the ecological sustainable development goals of low-carbon emission reduction, reducing environmental pollution, and reducing greenhouse gas emissions.

[0048] Reference Figure 3 The vibration-damping pile 3 includes a modified rubber coating layer 8, a support pipe 9 and a mixing pile 10 from the outside to the inside. The modified rubber coating layer 8 is sleeved on the outer surface of the support pipe 9, and the mixing pile 31 is arranged inside the support pipe 9. The modified rubber coating layer 8 is formed by mixing and stirring concrete materials. The thickness of the modified rubber coating layer 8 is 10 mm, the inner diameter of the support pipe 9 is 100 mm, the outer diameter is 110 mm, and the length is 3 m. The modified soil layer 2 is formed by mixing and injecting grouting cementitious materials into the surface soil layer of the foundation 4. The depth of the modified soil layer 2 is 100 mm. The grouting cementitious materials are polymer geopolymer concrete materials. This embodiment adopts a pile foundation form in which a support pipe 9 is wrapped with a modified rubber coating layer 8 and sleeved on the outer surface of a mixing pile 10. On the one hand, it can effectively improve the stress performance of the soil layer of the foundation 4, and can significantly enhance the fatigue damage resistance of the soil layer of the foundation 4 under the long-term dynamic cycle load of the subway, reduce the uneven settlement of the foundation 4, improve the bearing capacity of the foundation 4, realize the control of the unevenness of the subway track, reduce the wheel-rail impact noise, and alleviate the wear and damage of the rail. On the other hand, the modified rubber coating layer 8 wraps the support pipe 9 and the soil layer of the foundation 4 to form a three-component local resonance phononic crystal structure, and the mixing pile 10 itself formed by mixing a high molecular weight geopolymer concrete material can also serve as a three-component local resonance phononic crystal structure. Under the joint action of the two, the elastic wave propagation path transmitted by the subway vibration through the soil can be effectively cut off, thereby reducing the adverse effects of the subway vibration.

[0049] The vibration isolation wall 1, the vibration reduction pile 3, the ballast bed 5 and the vibration reduction wall 7 are all made of high molecular geopolymer concrete material; the high molecular geopolymer concrete material includes the following components by weight: 642-875 parts of granulated blast furnace slag powder, 275-375 parts of fly ash, 92-125 parts of silica fume, 1326-1807 parts of coarse aggregate, 1014-1382 parts of fine aggregate, 2-6 parts of modified foamed polystyrene polymer particles, 404-550 parts of alkali activator, 25-34 parts of high performance water reducer, and 242-330 parts of mixing water.

[0050] The particle size of the coarse aggregate is 15 to 25 mm, and it is one or more combinations of basalt, granite, and limestone, among which basalt is preferred; the fineness modulus of the fine aggregate is 1.5 to 2.5, and it is one or more combinations of river sand, machine-made sand, and recycled concrete fine aggregate.

[0051] The polystyrene polymer particles are prepared from expanded polystyrene polymer particles and a modifier; the particle size of the expanded polystyrene polymer particles is 1.5-3.0 mm; the modifier content is 1%-3%, and is one or more combinations of triethanolamine, polyvinyl alcohol, and guar gum ether.

[0052] The alkali activator is one or more combinations of alkali metal hydroxides, alkali silicates, alkali carbonates, and alkali sulfates, wherein a composite alkali activator of alkali metal hydroxides and alkali silicates is preferred; the high-performance water reducer is a high-performance polycarboxylic acid-based water reducer.

[0053] The present invention also provides a construction method of a vibration reduction and noise reduction structural system for a subway tunnel, comprising the following steps:

[0054] Step 1: Measure and lay out, initially level the site, inject grouting material into the soil within a certain depth range below the surface of foundation 4 and fully mix it with a mixer. Stop mixing after the mixed soil is solidified, and use a press to compact and level the solidified surface mixed soil of foundation 4 to ensure that the overall height difference of the surface soil layer of foundation 4 is no more than 10mm;

[0055] Step 2: excavate the earth and stone for pre-embedded vibration isolation wall 1 and vibration reduction pile 3 according to the direction, burial depth and distribution position of vibration isolation wall 1 and vibration reduction pile 3 specified in the design drawings;

[0056] Step 3: Wrap and fix the modified rubber coating layer 8 on the outer surface of the support tube 9, hoist the prefabricated vibration isolation wall 1 and the support tube 9 and place them in the corresponding positions after excavation, and pour the prepared polymer geopolymer concrete into the support tube 9 to form the vibration reduction pile 3; hoist the prefabricated integrated roadbed 5 and place it on the corresponding position of the surface layer of the foundation 4 to form a vibration reduction and vibration isolation foundation roadbed composite structure;

[0057] Step 4: According to the orientation of the vibration isolation wall 1, the sound insulation barrier layer 6 is hoisted and placed on the corresponding position of the surface of the foundation 4, and then the vibration reduction wall 7 is hoisted and placed closely on the sound insulation barrier layer 6 to form a sound insulation and vibration reduction composite structure.

[0058] In order to achieve the best vibration reduction effect, the three-component localized phononic crystal structure of the isolation wall is optimized. The proportion and gradation of the aggregate in the high molecular geopolymer concrete directly affect the strength of the concrete, and also affect its vibration reduction performance, mainly affecting the distribution of the band gap. In the following embodiments, the particle size of the aggregate (stone) is controlled according to the ratio, and the gradation curve is as follows: Figure 5 , the grading is required to be uniform and continuous.

[0059] Distribution of vibration reduction band gap of phononic crystal concrete:

[0060]

[0061]

[0062] Among them, H f is the effective vibration reduction frequency bandwidth of the structural system, is the filling rate of the ternary structure of pseudophononic crystal concrete;

[0063] n is the number of scatterers in the pseudophononic crystal aggregate, n = 5-6, r i is the radius of the unit cell scatterer, and a is the lattice constant of the pseudo-phononic crystal.

[0064] The band structure reflects the vibration wave transmission characteristics and vibration reduction performance in the phononic crystal. The band structure distribution is related to the lattice constant and filling rate of the phononic crystal. The lattice constant refers to the physical size of the unit cell in the lattice, and the filling rate refers to the degree to which the scatterer material of the unit cell is filled with its particles within a certain stacking volume. Its size reflects the density of the particles of the granular material filling each other. The optimization process of the three-component localized phononic crystal structure of the isolation wall will be specifically described in combination with specific embodiments.

[0065] Example 1

[0066] High molecular geopolymer concrete is the material used for the vibration isolation wall, modified soil layer, vibration reduction pile, foundation and roadbed in the present invention. According to the requirements of pseudo-phononic crystal vibration reduction, a three-component local resonance phononic crystal structure is made. The unit cell parameters of Scheme 1 are shown in Table 1. The lattice constant is 0.05m and the filling rate is 0.57. It can generate a broadband low-frequency band gap, which can effectively suppress and block the propagation of low-frequency elastic waves generated by vibration during subway operation, thereby significantly reducing the impact of low-frequency vibration.

[0067] Table 1 Equivalent stone structure parameters of high molecular geopolymer concrete (Scheme 1)

[0068]

[0069] Through finite element analysis and experimental determination (Plaxis+Comsol software, the same as in other embodiments), it is found that the polymer geopolymer concrete has multiple band gaps, which are 0.5-35.6Hz, 47.7-54.7Hz, 59.0-66.1Hz, 69.6-74.8Hz, 77.1-93.9Hz, 98.3-142.8Hz, and the total effective band gap width is 115.7Hz. The energy band structure diagram is shown in Figure 5 .

[0070] Example 2

[0071] The polymer geopolymer concrete is made into a three-component local resonance phononic crystal structure. The unit cell parameters of Scheme 2 are shown in Table 2. The lattice constant is 0.06m and the filling rate is 0.51. It can generate a broadband low-frequency band gap, which can effectively suppress and block the propagation of low-frequency elastic waves generated by vibration during subway operation, thereby significantly reducing the impact of low-frequency vibration.

[0072] Table 2 Equivalent stone structure parameters of high molecular weight geopolymer concrete (Scheme 2)

[0073]

[0074] Through finite element analysis and experimental determination, it was found that polymer geopolymer concrete has multiple band gaps, which are 0.5-31.2Hz, 40.3-54.2Hz, 59.9-66.9Hz, 70.1-83.3Hz, 87.0-111.5Hz, 124.8-130.6Hz, and the total effective band gap width is 95.1Hz. The energy band structure diagram is shown in Figure 6 .

[0075] Example 3

[0076] The polymer geopolymer concrete is made into a three-component local resonance phononic crystal structure. The unit cell parameters of Scheme 3 are shown in Table 3. The lattice constant is 0.075m and the filling rate is 0.47. It can generate a broadband low-frequency band gap, which can effectively suppress and block the propagation of low-frequency elastic waves generated by vibration during subway operation, thereby significantly reducing the impact of low-frequency vibration.

[0077] Table 3 Equivalent stone structure parameters of high molecular geopolymer concrete (Scheme 3)

[0078]

[0079] Through finite element analysis and experimental determination, it was found that polymer geopolymer concrete has multiple band gaps, which are 0.5-27.7Hz, 35.3-48.2Hz, 52.9-65.6Hz, 70.1-81.8Hz, 87.0-98.6Hz, 104.9-111.0Hz, and the total effective band gap width is 82.2Hz. The energy band structure diagram is shown in Figure 7 .

[0080] Example 4

[0081] The polymer geopolymer concrete is made into a three-component local resonance phononic crystal structure. The unit cell parameters of Scheme 4 are shown in Table 4. The lattice constant is 0.05m and the filling rate is 0.52. It can generate a broadband low-frequency band gap, which can effectively suppress and block the propagation of low-frequency elastic waves generated by vibration during subway operation, thereby significantly reducing the impact of low-frequency vibration.

[0082] Table 4 Equivalent stone structure parameters of high molecular weight geopolymer concrete (Scheme 4)

[0083]

[0084] Through finite element analysis and experimental determination, it was found that polymer geopolymer concrete has multiple band gaps, which are 0.5-37.0Hz, 47.5-56.7Hz, 61.7-70.5Hz, 74.4-83.0Hz, 86.2-108.3Hz, 119.7-137.6Hz, and the total effective band gap width is 103.1Hz. The energy band structure diagram is shown in Figure 8 .

[0085] Example 5

[0086] The polymer geopolymer concrete is made into a three-component local resonance phononic crystal structure. The unit cell parameters of Scheme 5 are shown in Table 5. The lattice constant is 0.05m and the filling rate is 0.41. It can generate a broadband low-frequency band gap, which can effectively suppress and block the propagation of low-frequency elastic waves generated by vibration during subway operation, thereby significantly reducing the impact of low-frequency vibration.

[0087] Table 5 Equivalent stone structure parameters of high molecular geopolymer concrete (Scheme 5)

[0088]

[0089] Through finite element analysis and experimental determination, it was found that polymer geopolymer concrete has multiple band gaps, which are 0.5-35.5Hz, 46.6-68.1Hz, 85.7-88.1Hz, 91.0-94.6Hz, 97.2-107.3Hz, 119.6-125.2Hz, and the total effective band gap width is 78.3Hz. The energy band structure diagram is shown in Fig. 9 .

[0090] From the energy band structure diagrams and related parameters of the above five embodiments, it can be seen that the lattice constants are all 0.05m, and the total effective band gap width increases with the increase of the filling rate. When the particle gradation of the scatterer is uniform, it is conducive to the increase of the total effective band gap width. At the same time, the increase of the lattice constant slightly reduces the total effective band gap width. In summary, in order to achieve a good vibration reduction effect for polymer geopolymer concrete, it is recommended to first control the filling rate, which is greater than 0.52, and then control the size of each unit cell itself, or reasonably grade it to meet the optimal coupling between the lattice constant and the filling rate. It is recommended that the maximum particle size of the scatterer is less than 0.03m, which is conducive to controlling the gradation of the aggregate. Scheme 1 has the largest total band gap width and the best vibration reduction control effect. Its unit cell constant is 0.01m and the filling rate is 0.57.

Claims

1. A low-frequency vibration reduction structural system for subway tunnels, It is characterized in that It includes a vibration-damping and vibration-isolating foundation and ballast composite structure and a sound-insulating and vibration-damping composite structure; the vibration-damping and vibration-isolating foundation and ballast composite structure includes a vibration-isolating wall, a modified soil layer, a vibration-damping pile, a foundation and a ballast, the vibration-damping wall is inserted into the interior of the foundation to form boundaries on both sides, the modified soil layer is arranged at the top of the groove formed by the vibration-damping wall and the foundation, the vibration-damping pile passes through the modified soil layer and the foundation in sequence from top to bottom, and the bottom of the vibration-damping pile is arranged flush with the bottom of the vibration-damping wall, and the ballast is arranged on the top of the modified soil layer; the materials of the vibration-damping wall, the vibration-damping pile, the foundation and the ballast are all high-molecular-weight geopolymer concrete.

2. The low-frequency vibration reduction structural system for a subway tunnel according to claim 1, It is characterized in that The vibration-damping pile comprises a modified rubber coating, a support pipe and a mixing pile. The modified rubber coating is sleeved on the outer surface of the support pipe, and the mixing pile is arranged inside the support pipe and is formed by mixing concrete. The modified soil layer is formed by injecting grouting cementitious materials into the foundation surface soil layer and mixing them.

3. The low-frequency vibration and noise reduction structural system for a subway tunnel according to any one of claims 1 to 2, It is characterized in that The polymer geopolymer concrete material includes the following components by weight: 642-875 parts of granulated blast furnace slag powder, 275-375 parts of fly ash, 92-125 parts of silica fume, 1326-1807 parts of coarse aggregate, 1014-1382 parts of fine aggregate, 2-6 parts of polystyrene polymer particles, 404-550 parts of alkali activator, 25-34 parts of high-performance water reducing agent, and 242-330 parts of mixing water.

4. The low-frequency vibration and noise reduction structural system for subway tunnels according to claim 3, It is characterized in that The coarse aggregate has a particle size of 15 to 25 mm and is a combination of one or more of basalt, granite, and limestone; the fine aggregate has a fineness modulus of 1.5 to 2.5 and is a combination of one or more of river sand, machine-made sand, and recycled concrete fine aggregate.

5. The low-frequency vibration and noise reduction structural system for subway tunnels according to claim 3, It is characterized in that The polystyrene polymer particles are prepared from expanded polystyrene polymer particles and a modifier; the particle size of the expanded polystyrene polymer particles is 1.5-3.0 mm; the modifier is added in an amount of 1%-3%, and is one or more combinations of triethanolamine, polyvinyl alcohol, and guar gum ether.

6. The low-frequency vibration and noise reduction structural system for subway tunnels according to claim 3, It is characterized in that The alkali activator is one or more combinations of alkali metal hydroxides, alkali silicates, alkali carbonates, and alkali sulfates, wherein a composite alkali activator of alkali metal hydroxides and alkali silicates is preferred; the high-performance water reducer is a high-performance polycarboxylic acid-based water reducer.

7. The design method of the low-frequency vibration and noise reduction structural system for subway tunnels according to claim 1 or 3, It is characterized in that The polymer geopolymer concrete is a ternary structure of phononic crystal concrete, and each parameter satisfies the following conditions: Among them, H f is the effective vibration reduction frequency bandwidth of the structural system, is the filling rate of the ternary structure of pseudophononic crystal concrete; n is the number of scatterers in the pseudophononic crystal aggregate, n = 5-6, r i is the radius of the unit cell scatterer, a is the lattice constant of the pseudophononic crystal; Therefore, each performance parameter directly affects the strength, vibration reduction performance and band gap distribution of concrete; it is necessary to first control the filling rate of high molecular weight geopolymer concrete Then control the size or gradation of each unit cell to achieve the best coupling between lattice constant and filling rate. Therefore, it is recommended that the maximum particle size of the unit cell scatterer is r i Less than 0.03m, so as to control the grading of aggregate.

8. The construction method of the low-frequency vibration and noise reduction structural system for subway tunnels according to claim 1, It is characterized in that The following steps are involved: Step 1: Measure and lay out, initially level the site, inject grouting materials into the soil under the surface of the foundation and mix it thoroughly with a mixer. Stop mixing after the mixed soil has solidified, and use a press to compact and level the solidified surface soil of the foundation to ensure that the overall height difference of the soil layer on the foundation surface is no more than 10mm; Step 2: Excavate the earth and stone for pre-embedded vibration isolation walls and vibration reduction piles according to the direction, burial depth and location of the vibration isolation walls and vibration reduction piles specified in the design drawings; Step 3: Wrap and fix the modified rubber coating layer on the outer surface of the support pipe, hoist the prefabricated vibration isolation wall and support pipe and place them in the corresponding positions after excavation, and pour the prepared concrete material into the support pipe to form vibration reduction piles; hoist the prefabricated integrated ballast and place it on the corresponding position of the foundation surface to form a vibration reduction and vibration isolation foundation ballast composite structure; Step 4: According to the location of the vibration isolation wall, the sound insulation barrier layer is hoisted and placed on the corresponding position of the foundation surface, and then the vibration reduction wall is hoisted and placed closely on the sound insulation barrier layer to form a sound insulation and vibration reduction composite structure; in this way, an overall structure of vibration reduction and noise reduction is formed by the vibration isolation wall, vibration reduction piles, modified soil layer and sound insulation barrier, realizing an efficient vibration reduction and noise reduction system for subway rail transit.

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