Composite material suitable for subway vibration reduction sleeper and application of composite material

Abstract

The invention relates to a composite material suitable for a subway vibration reduction sleeper and application of the composite material. The composite material comprises a matrix material, macromolecular particles accounting for 15-20% of the volume of the matrix material, a scatterer, magnesium oxide powder accounting for 1.0-1.5% of the use amount of cement, and calcium fluosilicate accounting for 0.5-0.8% of the use amount of the cement. The composite material is poured into a periodic layered structure including but not limited to a wave shape, a spiral shape or a streamline shape by adopting a printing nozzle, a band gap filtering effect on vibration wave propagation is achieved, and the maximum attenuation amplitude is 6-8 dB. The method can be used for preparing the subway vibration reduction sleeper. And the defect of short service life of the existing vibration reduction product is overcome, and long-acting vibration reduction can be realized.

Description

Technical Field

[0001] The present invention relates to a composite material applicable to a subway vibration damping sleeper and its application, belonging to the technical field of vibration control in track engineering. Background Art

[0002] As an important part of urban transportation facilities, urban rail transit shoulders the important responsibility of leading the ecological, efficient and diversified development of the city, and can be roughly divided into subways, light rails, intercity railways, etc. Among them, the subway, as the most effective public transportation facility in densely populated urban areas, has the advantages of large carrying capacity, safety and comfort, intensification, punctuality all-weather, etc., and plays an indispensable and important role in alleviating urban transportation congestion. However, the continuous and repeated low-frequency vibration characteristics of the subway running across urban buildings have brought non-negligible problems to the surrounding environment and the physical health of nearby residents.

[0003] First of all, the continuous and repeated vibrations generated during the operation of rail transit gradually spread to the ground building structure through the surrounding medium soil layer, thereby inducing secondary vibrations in the building structure, and then causing uneven settlement, fatigue cracking damage or even collapse of the building foundation, especially damaging the continuity of ancient building sites, and seriously reducing the functional accuracy and service life of precision instrument equipment. Secondly, the long-term vibration of the subway easily causes the vibration liquefaction of the shallow buried soil layer around it, resulting in serious over-standard cumulative settlement deformation, causing leakage in the tunnel lining structure in the later stage. Over time, water and sand gushing phenomena occur, leading to large-area uneven settlement and tunnel structure deformation and damage on the ground. In history, there was an event where the subway tunnel segments in a certain city leaked water and caused the suspension of operation. It was because the subway trains vibrated all year round, resulting in vibration liquefaction and settlement leakage of the silty sand soil layer through which the tunnel passed, showing the importance of long-term vibration damping. Thirdly, the long-term repeated low-frequency vibration frequency of the subway highly coincides with the natural vibration frequency of the main organs of the human body, which will cause irreversible serious damage to the physical and mental health of residents and reduce the sense of happiness in life.

[0004] Existing subway roadbeds and sleepers are mostly made of ordinary Portland cement concrete and belong to a rigid structure system without vibration damping function; due to the high cost of existing vibration damping technologies, anti-vibration measures are only provided at important nodes and key protection sections. Traditional subway vibration damping technical measures are mostly viscoelastic damping materials or external rigid components, with poor structural integrity, unstable service performance, and frequent replacement, which invisibly increases the construction and operation and maintenance costs of the subway.

[0005] In view of this, it is necessary to provide a new type of subway low-frequency vibration damping technology and product with low cost and long-term vibration damping to solve or at least improve the current defects of subway vibration damping technology. Summary of the Invention

[0006] To overcome the technical problems of poor low-frequency vibration damping effect and high cost in existing subways, the purpose of the present invention is to provide a composite material applicable to subway vibration damping sleepers and its application. The composite material is based on the phonon crystal theory and forms a unit cell-like structure with the characteristic of elastic vibration wave propagation bandgap through the combination of different materials. By utilizing this bandgap characteristic, the attenuation of elastic vibration waves is achieved, overcoming the disadvantages of poor low-frequency vibration damping effect and inability to adjust the vibration damping frequency in existing vibration damping technologies. Moreover, it has the characteristics of corrosion resistance and weather resistance, enhancing the service life of the vibration damping sleepers and realizing long-term vibration damping.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions: A composite material applicable to subway vibration damping sleepers, comprising: matrix material, polymer microparticles accounting for 15 - 20% of the volume of the matrix material, scatterers, magnesium oxide powder accounting for 1.0 - 1.5% of the cement dosage, and calcium fluosilicate accounting for 0.5 - 0.8% of the cement dosage.

[0008] The matrix material is conventional cement mortar with a strength reaching above C50.

[0009] The scatterers are selected from stones or slag, with a particle size between 5 - 25 mm and meeting the non-uniformity coefficient Cu≥2. The polymer microparticles need to meet: the density of the polymer microparticle glue is 11.0 - 13.5 kg / m 3 , and the water-binder ratio is between 0.23 - 0.26; adding polymer microparticles is to improve the vibration damping effect.

[0010] Magnesium oxide reacts with calcium sulfate in the cement to generate CaMg(SiO4)2, which is beneficial to the strength of the alkali-activated composite concrete and promotes the rapid setting, hardening, and stabilization of the composite concrete; calcium fluosilicate is used to control the pH value and hardness of the concrete.

[0011] The above composite material has the properties of a pseudo-phonon crystal, is cast into a periodic layered structure with a wavy or spiral or streamline shape, and has a bandgap filtering effect on the propagation of vibration waves, thereby achieving long-term vibration damping with a maximum attenuation amplitude of 6 - 8 dB and can be used for the preparation of subway vibration damping sleepers.

[0012] A preparation method for subway vibration damping sleepers, the steps are as follows: The first step: material selection; to reduce the manufacturing cost of the vibration damping sleepers, we select stones or slag as scatterers, with a particle size between 5 - 25 mm and meeting the non-uniformity coefficient Cu≥2; to achieve the vibration damping effect, polymer microparticles are incorporated into the matrix material, and the volume ratio of the polymer microparticles is 15 - 20%, and the density of the polymer microparticle glue is 11.0 - 13.5 kg / m 3 , and the water-binder ratio is between 0.23 - 0.26; the matrix material is made of cement mortar with a strength reaching above C50.

[0013] Step 2: Selection of additives; To make the composite concrete meet the strength requirements, an appropriate amount of magnesium oxide powder is selected and the proportion is controlled at 1.0 - 1.5% of the cement dosage. Magnesium oxide reacts with calcium sulfate in the cement to form CaMg(SiO4)2, which utilizes the strength of magnesium oxide alkali-activated composite concrete and promotes the rapid setting, hardening, and stabilization of the composite concrete. At the same time, calcium fluosilicate at 0.5 - 0.8% of the cement dosage is incorporated. Calcium fluosilicate reacts with magnesium ions in magnesium oxide to form water-insoluble fluosilicates, enhancing the pH value and hardness of the concrete.

[0014] Step 3: Selection of concrete printing nozzles; Select the nozzle type according to different shaping forms. A single-tube nozzle is used for the wave shape, a double-tube nozzle is used for the spiral shape, and a parallel triple-tube inclined nozzle is used for the streamline shape. Determine the selection of the pressure, speed, and quantity of the composite concrete during spraying, as well as the rotation method.

[0015] Step 4: Preparation of the mold box; According to the pre-designed pouring plan, pour concrete layers of different shapes in layers, such as wave shape, spiral shape, streamline shape, etc. These shapes are distributed periodically to form a sleeper in the form of a phononic crystal.

[0016] Step 5: Raw material preparation; The raw materials are injected into the mixing bin according to the ratio for preparation. The temperature during preparation is controlled between 35~45°C. This temperature is beneficial to the fluidity and workability of the composite concrete production. Then, it is pumped under pressure to the printer nozzle for pouring.

[0017] Step 6: Sleeper production; During production, pour layer by layer. When pouring into a wave shape or spiral shape, the spraying pressure of the composite concrete is controlled at 50 - 100 kPa. When pouring into a streamline shape, the spraying pressure of the composite concrete is controlled at 100 - 150 kPa. Pour to form a periodic structure of wave shape, spiral shape, or streamline shape. The thickness of each layer is 3 - 4 cm, and 5 - 6 layers are poured, with a total thickness of 18 - 20 cm.

[0018] Step 7: Curing after pouring; After each sleeper is produced, carry out steam curing for 6 h, then let it stand for 24 h before demolding. After demolding, carry out water curing for 5 - 7 days, and the water temperature for water curing is not lower than 10°C. After water curing, let it stand in a flat area for 20 days.

[0019] Beneficial effects: The present invention mainly has the following advantages: (1) The present invention uses cement mortar as the matrix material, adds polymer microparticles and scatterers, and uses magnesium oxide powder to alkali-activate the strength of the composite concrete and promote the rapid setting, hardening and stabilization of the composite concrete. Calcium fluosilicate is incorporated to enhance the pH value and hardness of the concrete; the obtained composite material has the properties of a phononic crystal, is cast into a periodic layered structure with a wavy, spiral or streamline shape, and has a bandgap filtering effect on the propagation of vibration waves, thereby achieving long-term vibration reduction with a vibration reduction effect of 6-8 dB, and can be used for the preparation of subway vibration reduction sleepers.

[0020] (2) The present invention uses a composite material with the properties of a phononic crystal, and uses a printing nozzle to pour concrete layers of different shapes (such as wavy, spiral, streamline, etc.) in layers. These shapes are periodically distributed to prepare a composite phononic crystal type sleeper, which has the characteristics of corrosion resistance and weather resistance, enhances the long-term service performance of the vibration reduction sleeper, and achieves long-term vibration reduction. Specific implementation manner

[0021] A method for preparing a subway vibration reduction sleeper, the steps are as follows: The first step: selection of materials; to reduce the manufacturing cost of the vibration reduction sleeper, we select stones or slag as scatterers, the particle size of which is between 5-25 mm and satisfies the non-uniformity coefficient Cu≥2; to achieve the vibration reduction effect, polymer microparticles are incorporated into the matrix material, and the volume ratio of the polymer microparticles is 15-20%, and the density of the polymer microparticle glue is 11.0-13.5 kg / m 3 , and the water-binder ratio is between 0.23-0.26; the matrix material is made of cement mortar, and the strength reaches above C50.

[0022] The second step: selection of additives; to make the composite concrete meet the strength requirements, an appropriate amount of magnesium oxide powder is selected and the proportion is controlled at 1.0-1.5% of the cement dosage. Magnesium oxide reacts with calcium sulfate in the cement to form CaMg(SiO4)2, and the strength of the composite concrete is alkali-activated by magnesium oxide and the composite concrete is promoted to set, harden and stabilize quickly; at the same time, 0.5-0.8% of the cement dosage of calcium fluosilicate is incorporated. Calcium fluosilicate reacts with magnesium ions in magnesium oxide to form water-insoluble fluorosilicates, enhancing the pH value and hardness of the concrete.

[0023] The third step: selection of the concrete printing nozzle; select the nozzle type according to different shaping. A single-tube nozzle is used for the wavy shape, a double-tube nozzle is used for the spiral shape, and a parallel three-tube inclined nozzle is used for the streamline shape. Determine the selection of the pressure, speed and quantity of the composite concrete during spraying, and the selection of the rotation method.

[0024] The fourth step: prepare the mold box; according to the pre-designed pouring scheme, pour concrete layers of different shapes in layers, such as wavy, spiral, streamline, etc. These shapes are periodically distributed to form a composite phononic crystal type sleeper.

[0025] Step 5: Raw material preparation; The raw materials are injected into the mixing bin according to the ratio for preparation. The temperature during preparation is controlled between 35 and 45 °C. This temperature is beneficial to the fluidity and workability of the composite concrete. Then, it is pumped under pressure and conveyed to the printer nozzle for pouring.

[0026] Step 6: Sleeper production; During production, it is poured layer by layer. When pouring into a wave shape or spiral shape, the ejection pressure of the composite concrete is controlled at 50 - 100 kPa. When pouring into a streamline shape, the ejection pressure of the composite concrete is controlled at 100 - 150 kPa. A periodic structure in the shape of a wave, spiral, or streamline is formed. The thickness of each layer is 3 - 4 cm, and 5 - 6 layers are poured, with a total thickness of 18 - 20 cm.

[0027] Step 7: Curing after pouring; After each sleeper is produced, it is steam-cured for 6 h, then left to stand for 24 h before the formwork can be removed. After formwork removal, it is water-cured for 5 - 7 days, and the water temperature for water-curing is not lower than 10 °C. After water-curing, it is left to stand in a flat area for 20 days.

[0028] In Examples 1 to 3, single-factor assessments were carried out on the key parameters during the preparation process. The polymer microparticle material used in the following examples is: polystyrene microparticles, with an average particle size of 1.0 mm.

[0029] Example 1 The dosage of the polymer microparticles is fixed at 18%, the lattice constant is taken as 10 cm, and the type of the periodic layered structure is changed: (1) In a wave shape: 0 - 21.95 Hz, 40.13 - 46.79 Hz, 51.25 - 55.93 Hz, 59.25 - 68.02 Hz, 71.76 - 81.96 Hz, 112.39 - 121.88 Hz, and 234.21 - 240.35 Hz, with a total bandwidth of 68.91 Hz, and the maximum attenuation amplitude can reach 7.8 dB.

[0030] (2) In a spiral shape: 0 - 22.23 Hz, 39.06 - 46.11 Hz, 51.64 - 56.01 Hz, 58.73 - 68.32 Hz, 71.76 - 82.83 Hz, 111.52 - 122.16 Hz, and 232.81 - 242.61 Hz, with a total bandwidth of 74.75 Hz, and the maximum attenuation amplitude can reach 9.7 dB.

[0031] (3) Streamlined: 0 - 20.36 Hz, 40.38 - 45.95 Hz, 50.81 - 55.16 Hz, 58.86 - 67.12 Hz, 71.05 - 80.13 Hz, 112.01 - 120.72 Hz, and 233.71 - 239.06 Hz, with a total bandwidth of 61.68 Hz and a maximum attenuation amplitude of up to 6.2 dB.

[0032] Among them, the vibration damping effect of the sleeper with a spiral periodic structure is the best.

[0033] Example 2

[0034] The fixed periodic layered structure type is spiral, and the lattice constant is taken as 10 cm: Change the dosage of polymer microparticles: (1) The dosage of polymer microparticles is 15%: 0 - 20.47 Hz, 39.34 - 45.26 Hz, 51.02 - 55.27 Hz, 58.13 - 67.22 Hz, 71.76 - 80.06 Hz, 111.39 - 120.08 Hz, and 233.51 - 240.08 Hz, with a total bandwidth of 63.29 Hz and a maximum attenuation amplitude of up to 6.2 dB.

[0035] (2) The dosage of polymer microparticles is fixed at 18%: 0 - 22.23 Hz, 39.06 - 46.11 Hz, 51.64 - 56.01 Hz, 58.73 - 68.32 Hz, 71.76 - 82.83 Hz, 111.52 - 122.16 Hz, and 232.81 - 242.61 Hz, with a total bandwidth of 74.75 Hz and a maximum attenuation amplitude of up to 9.7 dB.

[0036] (3) The dosage of polymer microparticles is 20%: 0 - 24.19 Hz, 39.06 - 47.22 Hz, 51.71 - 57.12 Hz, 58.46 - 68.93 Hz, 71.25 - 83.42 Hz, 111.03 - 123.94 Hz, and 234.92 - 242.67 Hz, with a total bandwidth of 81.06 Hz and a maximum attenuation amplitude of up to 10.3 dB.

[0037] It can be seen that as the dosage of polymer microparticles increases from 15% to 20%, the vibration damping effect improves successively, but the manufacturing cost increases accordingly. In terms of cost performance, the cost performance of the dosage of polymer microparticles fixed at 18% is the best, and the vibration damping effect is also acceptable.

[0038] Example 3

[0039] The fixed periodic layered structure type is spiral and the dosage of polymer microparticles is 18%, change the lattice constant of the periodic structure: (1) The lattice constant is 8 cm: 0 - 18.52 Hz, 40.01 - 44.35 Hz, 52.10 - 56.12 Hz, 58.94 - 68.03 Hz, 73.86 - 82.15 Hz, 112.39 - 123.23 Hz, and 245.51 - 261.31 Hz. The total bandwidth is 70.9 Hz, and the maximum attenuation amplitude can reach 8.9 dB.

[0040] (2) The lattice constant is 10 cm: 0 - 22.23 Hz, 39.06 - 46.11 Hz, 51.64 - 56.01 Hz, 58.73 - 68.32 Hz, 71.76 - 82.83 Hz, 111.52 - 124.16 Hz, and 233.81 - 241.61 Hz. The total bandwidth is 74.75 Hz, and the maximum attenuation amplitude can reach 9.68 dB.

[0041] (3) The lattice constant is 12 cm: 0 - 23.19 Hz, 38.12 - 46.02 Hz, 51.70 - 57.31 Hz, 58.54 - 68.72 Hz, 71.33 - 83.91 Hz, 111.23 - 123.85 Hz, and 234.92 - 239.67 Hz. The total bandwidth is 76.83 Hz, and the maximum attenuation amplitude can reach 9.8 dB.

[0042] It can be seen that as the lattice constant increases, the bandgap width in the low - frequency band increases, and the bandgap width in the high - frequency band slightly decreases, which is beneficial to low - frequency vibration reduction.

[0043] In summary, as the proportion of polymer particles increases, the total bandwidth of the vibration - reduction bandgap increases, and the vibration - reduction effect also increases. It is mainly the increase in the high - frequency bandgap, which is beneficial to the attenuation of frequencies below 100 Hz. The sleeper with a spiral periodic structure is more beneficial for vibration reduction. It is more reasonable to take a lattice constant of 10 cm for the design and manufacture of the sleeper.

[0044] The technical features of the above - described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above - described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0045] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above - described embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A composite material applicable to subway vibration damping sleepers, characterized in that, Comprising: Matrix material, polymer microparticles accounting for 15 - 20% of the volume of the matrix material, scatterers, magnesium oxide powder accounting for 1.0 - 1.5% of the cement dosage, and calcium fluosilicate accounting for 0.5 - 0.8% of the cement dosage; The matrix material is conventional cement mortar with a strength reaching above C50; The scatterers are selected from stones or slag with a particle size between 5 - 25 mm and meeting the non-uniformity coefficient Cu ≥ 2; The density of the polymer microparticles is 11.0 - 13.5 kg / m 3 , and the water-cement ratio is between 0.23 and 0.26; Magnesium oxide reacts with calcium sulfate in the cement to form CaMg(SiO4)2, which is beneficial to the strength of the alkali-activated composite concrete and promotes the rapid setting, hardening, and stabilization of the composite concrete; calcium fluosilicate is used to control the pH value and hardness of the composite material.

2. Application of the composite material according to claim 1 in the preparation of subway vibration-damping sleepers.

3. The application according to claim 2, wherein The composite material is cast into a periodic layered structure including but not limited to a wavy, spiral, or streamline shape by a printing nozzle, which has a bandgap filtering effect on the propagation of vibration waves, and the maximum attenuation amplitude is 6 - 8 dB.

4. A preparation method of a subway vibration damping sleeper, characterized in that, The steps are as follows: The first step: Selection of materials; To reduce the manufacturing cost of the vibration damping sleeper, gravel or slag is selected as the scatterer, with a particle size between 5 - 25 mm and meeting the coefficient of non-uniformity Cu≥2; To achieve the vibration damping effect, polymer microparticles are incorporated into the matrix material, with the volume ratio of the polymer microparticles being 15 - 20% and the density of the polymer microparticles being 11.0 - 13.5 kg / m 3 , and the water-cement ratio is between 0.23 - 0.26; The matrix material is made of cement mortar with a strength of C50 or above; The second step: Selection of additives; To make the composite concrete meet the strength requirements, magnesium oxide powder is incorporated, and the proportion is controlled at 1.0 - 1.5% of the cement dosage. Magnesium oxide reacts with calcium sulfate in the cement to form CaMg(SiO4)2, utilizing the strength of magnesium oxide to alkali-activate the composite concrete and promoting the rapid setting, hardening, and stabilization of the composite concrete; at the same time, calcium fluosilicate accounting for 0.5 - 0.8% of the cement dosage is incorporated. Calcium fluosilicate reacts with magnesium ions in magnesium oxide to form water-insoluble fluorosilicates, enhancing the pH value and hardness of the concrete; The third step: Selection of the concrete printing nozzle; Select the nozzle type according to different shapes. A single-tube nozzle is used for the wavy shape, a double-tube nozzle is used for the spiral shape, and a parallel three-tube inclined nozzle is used for the streamline shape; Determine the selection of the pressure, speed, and quantity of the composite concrete during spraying, and the selection of the rotation method; The fourth step: Preparation of the mold box; According to the pre-designed pouring plan, layer by layer pour concrete layers in different forms, such as wavy, spiral, streamline, etc. These shapes are periodically distributed and combined into a phonon crystal-type sleeper; The fifth step: Raw material preparation; The raw materials are injected into the mixing bin according to the ratio for preparation. The temperature during preparation is controlled between 35 - 45 °C. This temperature is beneficial to the fluidity and workability of the composite concrete, and then it is pumped and pressurized to be transported to the printer nozzle for pouring; The sixth step: Sleeper production; Layer by layer pouring construction to obtain the sleeper blank; The seventh step: Curing after pouring is completed.

5. The preparation method of a subway vibration damping sleeper according to claim 4, characterized in that, In the sixth step, when pouring the wavy and spiral shapes, the spraying pressure of the composite concrete is controlled at 50 - 100 kPa, and when pouring the streamline shape, the spraying pressure of the composite concrete is controlled at 100 - 150 kPa, pouring to form a periodic structure of wavy, spiral, or streamline shape; The thickness of each layer is 3 - 4 cm, and 5 - 6 layers are poured, with a total thickness of 18 - 20 cm.

6. The preparation method of a subway vibration damping sleeper according to claim 4, characterized in that, The specific operation method of the seventh step is: After each sleeper is produced, it is steam-cured for 6 h, then left to stand for 24 h before demolding, and after demolding, it is water-cured for 5 - 7 days, and the water temperature for water-curing is not lower than 10 °C. After water-curing, it is placed in a flat area and left to stand for 20 days.