CN111611635B - Design method of high-speed railway ballastless track high-low temperature test platform - Google Patents
Design method of high-speed railway ballastless track high-low temperature test platform Download PDFInfo
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Abstract
The invention provides a design method of a high-low temperature test platform of a ballastless track of a high-speed railway. The method comprises the following steps: establishing a high-low temperature test platform model of the ballastless track of the high-speed railway by using finite element software, wherein the high-low temperature test platform model comprises a test box library model, a test box base model, a working space fluid model and a ballastless track model, the test box library model is fixedly arranged on the test box base model, and the ballastless track model is fixedly arranged in the test box library model; and adjusting the component structure in the high-speed railway ballastless track high-low temperature test platform model according to the heat preservation effect, stability and applicability performance indexes of the high-speed railway ballastless track high-low temperature test platform model, and realizing the design and optimization of the ballastless track high-low temperature test platform. The method has the advantages of high visualization degree, flexible modeling configuration and comprehensive design factor consideration, and can provide a system and a complete design method for the establishment of a high-low temperature test platform of the ballastless track of the high-speed railway.
Description
Technical Field
The invention relates to the technical field of high-speed railway ballastless track tests, in particular to a design method of a high-low temperature test platform of a high-speed railway ballastless track.
Background
The high-speed railway ballastless track is used as a concrete structural project placed in a natural environment, is subjected to the influence of various natural environment condition changes, the temperatures of each point on the surface and the inside of the high-speed railway ballastless track change at any time, and temperature deformation and ballastless track diseases are generated.
Aiming at the problem of the damage of the ballastless track, at present, students at home and abroad develop outdoor tests, the outdoor tests not only need to consume a great deal of time, manpower and material resources, but also only study the influence of a temperature field on the stress of the track component aiming at a specific working point, and do not consider the influence of extreme high and low temperature, temperature circulation and the like on the generation and development of the damage of the track component. The test box of the ballastless track of the high-speed railway can conduct extremely high-low temperature and temperature circulation for carrying out indoor tests on the ballastless track so as to solve the test requirement which cannot be achieved outdoors, but the test box of the ballastless track of the high-speed railway for the indoor tests is not established at present, the platform construction is still in the early stage, and a systematic method for designing the test box of the ballastless track of the high-speed railway is not yet available.
Disclosure of Invention
The embodiment of the invention provides a design method of a high-low temperature test platform of a ballastless track of a high-speed railway, which aims to overcome the problems in the prior art.
In order to achieve the above purpose, the present invention adopts the following technical scheme.
A design method of a high-speed railway ballastless track high-low temperature test platform comprises the following steps:
establishing a high-low temperature test platform model of a ballastless track of a high-speed railway by using finite element software, wherein the high-low temperature test platform model comprises a test box library model, a test box base model, a working space fluid model and a ballastless track model, the test box library model is fixedly arranged on the test box base model, the working space fluid model is a fluid space which is not occupied by an object and needs to be heated or cooled in the test platform model, and the ballastless track model is fixedly arranged in the test box library model;
and adjusting the component structure in the high-speed railway ballastless track high-low temperature test platform model according to the heat preservation effect, stability and applicability performance indexes of the high-speed railway ballastless track high-low temperature test platform model, so as to design and optimize the ballastless track high-low temperature test platform.
Preferably, the library body plate of the test box library body model adopts a three-layer structure of an inner container, a middle heat-insulating layer and an outer container, wherein the inner container is made of stainless steel plates, the outer container is made of color steel plates, the middle heat-insulating layer is made of heat-insulating materials, and the inner container, the middle heat-insulating layer and the outer container are all simulated by adopting entity units.
Preferably, the test box base model adopts a form of steel plates plus a concrete base or an integral concrete foundation structure and is positioned at the bottom of the test box warehouse body model.
Preferably, the ballastless track model comprises a steel rail, a fastener unit, a track plate, a mortar layer, a supporting layer and a wide-narrow seam, wherein the steel rail is simulated by adopting a beam unit, the fastener unit is simulated by adopting a spring unit, the track plate, the mortar layer and the supporting layer are simulated by adopting a solid unit, longitudinal restraint on a longitudinally connected ballastless track is realized at the restraint end part of the ballastless track model by arranging a counterforce wall and a jack, the counterforce wall and the jack are simulated by adopting the solid unit, and the pre-compression of the jack is realized by heating a jack part.
Preferably, an air inlet part model and an air outlet part model are arranged at the junction of the test box body model and the working space fluid model, and the air inlet part model and the air outlet part model are cube fluid space parts with side length of 0.5 m.
Preferably, the method comprises:
establishing a space coupling heat transfer mathematical model of a high-speed railway ballastless track high-low temperature test platform by using finite element software, wherein the space coupling heat transfer mathematical model specifically comprises the following steps:
(1) The specific length, width and height dimensions of the high-low temperature test box body consider the elastic modulus, poisson ratio, density, expansion coefficient, heat conductivity coefficient and specific heat of the material;
(2) The specific length, width and height dimensions of the test box base take the elastic modulus, poisson ratio, density, expansion coefficient, heat conductivity coefficient and specific heat of the material into consideration;
(3) The working space fluid component is used for determining the size of an internal cuboid fluid space under the non-empty condition based on the size of a platform and a ballastless track structure for test paved in a test box, establishing the working space fluid component under the non-empty condition, and considering the density, expansion coefficient, thermal conductivity, specific heat and dynamic viscosity coefficient of air fluid;
(4) The air inlet and outlet component is set as a cube fluid space component with a certain size according to design requirements and is placed at the edge of the platform box body, and the density, the expansion coefficient, the thermal conductivity, the specific heat and the dynamic viscosity coefficient of air fluid are considered.
(5) The ballastless track structure for the test is modeled by considering longitudinal constraints at two ends and considering the actual thermal conductivity material properties and geometric dimensions of the ballastless track structure.
Preferably, the working space fluid model is used for calculating the internal air temperature field distribution under the heating condition and the cooling condition, and the position of the air inlet and outlet, the air inlet and outlet mode, the air inlet speed and the temperature set value are adjusted so as to meet the heat preservation and insulation performance requirements of the test platform.
Preferably, under the condition of the same thickness of the box body structure layer, the lower the heat conductivity coefficient of the heat preservation layer material, the larger the thermal resistance of the box body structure, the smaller the average heat conductivity coefficient of the box body, and the better the heat preservation and insulation performance of the test platform model.
Preferably, when the test platform model carries out a temperature-rising experiment, the air inlet and the air return opening are arranged on the same side of the test box body, and the air inlet is above the air return opening.
Preferably, the top warehouse body plate of the test box body is a top plate, the vertical displacement of the top plate is calculated by adopting a static analysis method under the condition of only considering the self weight of the structure, the thickness of the inner and outer structural layers of the top plate is increased, or a plurality of pairs of side support columns are arranged in a contrasting manner to support the test box warehouse body model, so that the vertical displacement of the top plate under the action of self gravity load is reduced.
According to the technical scheme provided by the embodiment of the invention, the design method of the high-speed railway ballastless track high-low temperature test platform is high in visualization degree, flexible in modeling configuration and comprehensive in design factor consideration, a system and a complete design method can be provided for building the high-speed railway ballastless track high-low temperature test platform, and the early working problem of the test platform is solved.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a structural perspective view of a high-low temperature test platform model of a ballastless track of a high-speed railway, which is provided by the embodiment of the invention;
FIG. 2 is a schematic diagram of a finite element model of a test chamber library model and a test chamber base model according to an embodiment of the present invention;
FIG. 3 is a schematic illustration of a working space fluid model provided in an embodiment of the present invention;
FIG. 4 is a schematic diagram of an air inlet model and an air outlet model according to an embodiment of the present invention;
FIG. 5 is a model diagram of a ballastless track structure in a test box provided by an embodiment of the invention;
FIG. 6 is a schematic diagram showing the vertical displacement of the top plate of the tank body before the improvement design under the action of dead weight according to the embodiment of the invention;
FIG. 7 is a schematic diagram showing a change in vertical displacement according to the thickening of a top plate structure according to an embodiment of the present invention;
FIG. 8 is a schematic view of vertical displacement of a top plate after placement of a support column according to an embodiment of the present invention;
FIG. 9 is a schematic diagram showing the thermal resistance of a box body with a thermal insulation layer made of different thermal insulation materials according to an embodiment of the present invention;
FIG. 10 is a schematic diagram showing comparison of average thermal conductivity coefficients of a case body with different insulating layer materials for an insulating layer according to an embodiment of the present invention;
FIG. 11 is a schematic diagram of the temperature of the outer wall of a thermal insulation layer according to an embodiment of the present invention when the thermal insulation layer is operated at low temperature using different materials;
FIG. 12 is a schematic diagram of three alternative air inlet and outlet modes, namely upper air inlet, lower air return, lower air inlet, upper air return, left air inlet and right air return, under the condition of temperature rise according to the embodiment of the invention;
FIG. 13 is a schematic view of selecting horizontal planes of different heights in the vertical direction in a test chamber according to an embodiment of the present invention;
FIG. 14 is a schematic view of a selected position of a No. 1 temperature node on each height level in a test chamber according to an embodiment of the present invention;
FIG. 15 is a schematic diagram of a vertical temperature gradient of air when a temperature raising mode of upper air intake and lower air return is adopted in the embodiment of the present invention;
FIG. 16 is a schematic diagram of a vertical air temperature gradient change curve in a heating mode of lower air intake and upper air return according to an embodiment of the present invention;
fig. 17 is a schematic diagram of a vertical air temperature gradient change curve in a heating mode of left air intake and right air return according to an embodiment of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present invention and are not to be construed as limiting the present invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless expressly stated otherwise, as understood by those skilled in the art. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
For the purpose of facilitating an understanding of the embodiments of the invention, reference will now be made to the drawings of several specific embodiments illustrated in the drawings and in no way should be taken to limit the embodiments of the invention.
The embodiment of the invention establishes a high-speed railway ballastless track test box model and a ballastless track space coupling heat transfer analysis model for internal test by using large-scale general finite element software, and designs a test box of the high-speed railway ballastless track.
The embodiment of the invention provides a design method of a high-low temperature test platform of a ballastless track of a high-speed railway based on an outside-in design principle. The method comprises the steps of establishing a high-low temperature test platform model of the ballastless track of the high-speed railway by using finite element software, wherein the high-low temperature test platform model comprises a test box base model, a working space fluid model and a ballastless track model, the test box base model is fixedly arranged on the test box base model, the working space fluid model is a fluid space which is not occupied by an object and needs to be heated or cooled in the test platform model, and the ballastless track model is fixedly arranged in the test box base model. Specific embodiments may employ ABAQUS large finite element software.
And adjusting the component structure in the high-speed railway ballastless track high-low temperature test platform model according to the heat preservation effect, stability and applicability performance indexes of the high-speed railway ballastless track high-low temperature test platform model, and realizing the design and optimization of the ballastless track high-low temperature test platform.
The method adopts means such as static analysis, modal analysis and harmonic response analysis to design the structural stability and safety of the test box library model and the test box foundation; designing the heat preservation and insulation performance of the test box library model through the structural heat transfer mathematical model of the test box library model; the working space fluid model analysis model established by utilizing the finite element CFD (Computational Fluid Dynamics fluid dynamics) module is utilized to design test parameters such as an air inlet and outlet mode, an air inlet speed, a test temperature set value and the like based on air temperature field uniformity analysis; through the ballastless track model for the test, an indoor constraint mode of the ballastless track for the test is designed, and the temperature loading mode of the ballastless track during the test is designed based on the heat convection and heat radiation principles. Based on the finite element model, the method steps are adopted, so that the design and optimization of the ballastless track test box are realized.
The structure diagram of the high-low temperature test platform model of the ballastless track of the high-speed railway is shown in fig. 1, and the structure diagram comprises a test box base model, a working space fluid model and a ballastless track model. The test box base model is fixedly arranged on the upper surface of the test box base model, and the ballastless track model is fixedly arranged in the test box base model.
A schematic diagram of a finite element model of a test box library model and a test box base model provided by the embodiment of the invention is shown in fig. 2, and the test box library model with high and low temperature is taken as a design main body, adopts a multilayer structure, and adopts a solid unit for modeling. The warehouse body plate of the high-low temperature test box warehouse body model adopts a three-layer structure form of an inner container, a middle heat-insulating layer and an outer container, wherein the inner container is made of stainless steel plates, the outer container is made of color steel plates, the middle heat-insulating layer is made of polyurethane hard foam materials and other heat-insulating materials, and the model is simulated by adopting entity units.
The test box base model adopts two structural forms of a steel plate and a concrete base and an integral concrete foundation, is positioned at the bottom of the test box base model, and is modeled by adopting entity units in the model.
Fig. 3 is a schematic diagram of a working space fluid model according to an embodiment of the present invention, and fig. 4 is a schematic diagram of an air intake component model and an air outlet component model according to an embodiment of the present invention. As shown in fig. 3 and fig. 4, the working space fluid model is a fluid space which is not occupied by an object and needs to be heated or cooled in the test platform model, the air inlet component and the air outlet component are positioned at the junction of the test box body model and the working space fluid model, and the 8-node hexahedral unit FC3D8 simulation commonly used in fluid simulation is adopted.
A schematic diagram of a ballastless track model provided by the embodiment of the invention is shown in fig. 5. The slab ballastless track model comprises a steel rail, a fastener unit, a track slab, a mortar layer, a supporting layer and a wide-narrow seam, wherein the steel rail is simulated by adopting a beam unit, the fastener unit is simulated by adopting a spring unit, and the track slab, the mortar layer and the supporting layer are simulated by adopting a solid unit.
The geometric dimension and the material applicability design of the structure composition of the test box are considered, and the length, width and height dimensions of the inner part of the test box body are respectively set to 26m, 5m and 3m. The elastic modulus, poisson ratio, density, expansion coefficient, thermal conductivity and specific heat of the materials used are considered.
The length, width and height dimensions of the test box base model are respectively set to 27m, 7m and 2m. The elastic modulus, poisson ratio, density, expansion coefficient, thermal conductivity and specific heat of the materials used are considered.
A cuboid fluid space with length, width and height of 26m, 5m and 3m is set under the empty load condition of the test box. Under the non-empty condition, namely, the ballastless track model structure paved in the test box occupies indoor space, the working space fluid model component under the non-empty condition can be built according to the size of the ballastless track model. Consider the density, expansion coefficient, thermal conductivity, specific heat, and dynamic viscosity coefficient of an air fluid. The air inlet and air outlet parts are square fluid space parts with side length of 0.5m, namely the cross section area of the air inlet and the air outlet is 0.25m2 for visual representation. Consider the density, expansion coefficient, thermal conductivity, specific heat, and dynamic viscosity coefficient of an air fluid.
A CRTS II plate type ballastless track model for the test is paved in the center of the inside of the test box, and comprises a steel rail, a fastener, a track plate, a CA mortar layer, a supporting layer, a wide-narrow seam and other structures, and actual material properties, geometric dimensions and two-end constraints are considered. The longitudinal restraint of the longitudinally connected ballastless track is realized in a mode that a counterforce wall and a jack are arranged at the restraint end part of the ballastless track, the counterforce wall and the jack are simulated by adopting entity units, and the pre-compression of the jack is realized by heating jack parts.
And (3) considering the safety design of the test platform, adopting finite element static force calculation, and calculating the vertical displacement of the top plate under the condition of only considering the dead weight of the structure. Adopting modal analysis in finite elements to simulate the characteristics of main modes of each order of the structure in a frequency range which is easy to be affected, and judging the actual vibration response of the structure under the action of a vibration source in the frequency range; the method comprises the steps of adopting harmonic response analysis in finite elements to determine steady-state response of a structure when the structure bears load changing along with a simple harmonic rule, only calculating steady-state forced vibration of the structure in the analysis process, calculating displacement-frequency curves of the structure at several frequencies without considering transient vibration at the beginning of excitation, predicting the sustainable dynamic characteristics of the structure, and verifying whether the design can overcome harmful effects caused by resonance, fatigue and other forced vibration. Judging the structural stability and vibration characteristics of the test platform; the structural stability of the test platform is optimized by arranging supporting columns for supporting, adjusting the thickness of the steel plate and the like.
The heat insulation performance design of the test box is considered, the indoor air of the test box is heated, after the temperature is raised, heat is transferred to the inner surface of the test box body model in an air convection heat exchange and heat radiation mode, heat is transferred to the outer surface of the box body from the inner surface of the box body in a heat conduction mode, the heat insulation capacity of the test box body enclosure structure is judged by calculating the heat conductivity coefficient, the heat flow density, the thermal resistance of the box body and the temperature of the outer wall of the box body, the thickness of the box body enclosure structure is adjusted according to the heat insulation capacity, whether a heat insulation layer is arranged is judged, and a proper heat insulation layer material is selected.
Considering the uniform design of the air temperature in the test box, setting the fluid inflow with speed and temperature at the air inlet of the working space fluid model, setting the fluid outflow with zero pressure at the air outlet, calculating the internal air temperature field distribution under the heating condition and the cooling condition by the working space fluid model analysis model established by the finite element CFD module, and adjusting the air inlet and outlet mode, the air inlet speed and the temperature set value to obtain the optimal air temperature uniformity in the test box.
And (3) through the established test box and the internal plate type ballastless track space coupling heat transfer mathematical model, adopting methods such as heat convection and heat radiation as boundary conditions of model temperature load, calculating to obtain an internal temperature field of the ballastless track for test, and further designing a temperature loading mode of the ballastless track for test.
The effectiveness of the invention is further illustrated in the following figures and examples:
example 1
In the embodiment, structural safety is analyzed, and an optimal design scheme of the ballastless track test box is provided by adopting the method for enhancing structural stability.
The box body of the test box mainly comprises an inner structural layer steel plate, an outer structural layer steel plate and an intermediate heat preservation layer, and adopts the design of 30mm of an inner container, 100mm of the heat preservation layer and 20mm of an outer container, and a top box body plate of the box body of the test box is a top plate. Through calculation of a finite element static analysis module, it is found that, due to the fact that the top plate is long in length and thin in inner and outer structural layers, fig. 6 is a schematic diagram of vertical displacement of the top plate of the box body before improved design under the action of dead weight, as shown in fig. 6, under the action of gravity, the vertical displacement of 11.83mm is generated at the maximum in the middle of the top plate, the sinking amount is large, and the structural stability is poor. The solution of contrasting the provision of pairs of lateral support columns to support or adjust the thickness of the roof of the box is considered to enhance the structural stability of the test box, wherein the support columns are schematically illustrated in fig. 1. Fig. 8 is a schematic view of vertical displacement of a top plate after a support column is arranged, and as can be seen from fig. 8, the vertical displacement of the top plate is reduced to a certain extent after the vertical support column is arranged, and the reduction of the vertical displacement of the top plate after the support column is arranged is not great because the bending stiffness of the top plate is smaller, and the reduction of the vertical displacement of the top plate is only reduced by 3.84mm after the support column is arranged.
Fig. 7 is a schematic diagram showing a change of vertical displacement along with thickening of a top plate according to an embodiment of the present invention, as shown in fig. 7, as the thickness of a structural layer steel plate increases, the vertical displacement of the top plate generated under the action of self gravity load gradually decreases, because the greater the thickness of the steel plate, the greater the bending stiffness of the steel plate, and the smaller the central sinking amount of the steel plate under the action of gravity load. When the thickening amount is 15mm, compared with the original situation, the displacement of the top plate is reduced by about 9mm, and the effect is obvious. Meanwhile, as the structural layer is thickened, the reduction rate of the vertical displacement of the top plate is gradually reduced, and when the thickening amount is increased from 0mm to 5mm, the vertical displacement is reduced by 6.1mm; when the thickening amount is increased from 15mm to 20mm, the vertical displacement is reduced by only 0.52mm.
In summary, according to the calculation of the method, the thickness of the structural layer of the top plate is increased, namely, the bending rigidity of the top plate is increased more effectively for controlling the vertical displacement of the top plate, the reinforcing effect and the material utilization rate can be comprehensively considered in actual design, and the inner structural layer and the outer structural layer of the top plate are respectively thickened by 15 mm.
Example 2
In the embodiment, the heat insulation performance of the enclosure structure is analyzed, the heat insulation capacity of the test box body is enhanced, and the optimal design scheme from the ballastless track to the low-temperature test box is provided by the method.
Establishing a space coupling heat transfer mathematical model of a high-speed railway ballastless track high-low temperature test platform by using finite element software, wherein the space coupling heat transfer mathematical model specifically comprises the following steps:
(1) The specific length, width and height dimensions of the high-low temperature test box body consider the elastic modulus, poisson ratio, density, expansion coefficient, heat conductivity coefficient and specific heat of the material;
(2) The specific length, width and height dimensions of the test box base take the elastic modulus, poisson ratio, density, expansion coefficient, heat conductivity coefficient and specific heat of the material into consideration;
(3) The working space fluid component is used for determining the size of an internal cuboid fluid space under the non-empty condition based on the size of a platform and a ballastless track structure for test paved in a test box, establishing the working space fluid component under the non-empty condition, and considering the density, expansion coefficient, thermal conductivity, specific heat and dynamic viscosity coefficient of air fluid;
(4) The air inlet and outlet component is set as a cube fluid space component with a certain size according to design requirements and is placed at the edge of the platform box body, and the density, the expansion coefficient, the thermal conductivity, the specific heat and the dynamic viscosity coefficient of air fluid are considered.
(5) The ballastless track structure for the test is modeled by considering longitudinal constraints at two ends and considering the actual thermal conductivity material properties and geometric dimensions of the ballastless track structure.
The heat-insulating materials for wall body which are commonly used in the construction industry at present comprise hard polyurethane foam materials, polystyrene foam boards (EPS boards), extruded polystyrene boards (XPS boards), glass wool boards, foam glass and the like, and the heat conductivity coefficients of the materials are shown in table 1.
TABLE 1 Heat conductivity coefficient of commonly used insulating layer materials/(W.m-1. K-1)
Aiming at the box body structure of the test box, the design of 30mm of the inner container, 100mm of the heat preservation layer and 20mm of the outer container is adopted in the test box, the heat transfer analysis and calculation are utilized, and under the condition that the material type of the heat preservation layer of the middle layer is only changed, the heat insulation capacity under the steady heat transfer through the box body is calculated.
Fig. 9 is a schematic diagram showing comparison of thermal resistances of a tank body with different insulating layer materials for an insulating layer according to an embodiment of the present invention, and fig. 10 is a schematic diagram showing comparison of average thermal conductivity coefficients of a tank body with different insulating layer materials for an insulating layer. As can be seen from fig. 9 and 10, the influence of different insulation materials on the insulation performance of the box body is mainly attributed to the thermal conductivity of the insulation materials. Under the condition of the same thickness of the box body structure layer, the lower the heat conductivity coefficient of the heat preservation layer material, the larger the heat resistance of the box body structure, the smaller the average heat conductivity coefficient of the box body, and the better the heat preservation and heat insulation performance. Under the same thickness of the structural layer, the thermal resistances of the boxes made of different heat-insulating layer materials are inversely related to the average thermal conductivity of the boxes.
The related technical requirements prescribe a test box body heat preservation performance test method: the temperature of the test box is stabilized at the highest working temperature point for 2 hours, and the temperature of the outer wall of the test box is checked by a surface thermometer, so that the temperature of the easily accessible part outside the test box can be ensured to be not higher than 50 ℃ in a high-temperature test; the temperature of the test box is stabilized at the lowest working temperature point for 2 hours, and the condition of the outer surface of the box is observed, so that the condensation phenomenon can be avoided when the temperature of the test box is tested at a low temperature and the ambient temperature is 15-35 ℃ and the relative humidity is less than or equal to 85%.
In order to ensure that the actual test box body meets the test requirement, namely the outer wall meets the condition that the condensation phenomenon does not occur at the room temperature of 20 ℃ and the relative humidity of 85%, the temperature of the outer wall of the box body adopting different heat preservation materials under the low-temperature working condition of the test box is calculated by the method, and the temperature is shown in figure 11. As shown in fig. 11, when the thickness of the insulation layer is 100mm, the requirement of no condensation on the outer wall can be satisfied by using the hard foam polyurethane with lower material heat conductivity and the XPS board as the insulation layer material; if EPS board, glass wool board, foam glass are used as the heat insulation layer material of the box body, the thickness of the heat insulation layer needs to be correspondingly increased so as to meet the heat insulation requirement of the box body.
In summary, the calculation by the method shows that the heat preservation layer with the thickness of 100mm adopts the hard foam polyurethane as the material, so that the requirement of the heat preservation performance of the box body can be met, and the heat preservation effect is optimal in a comparison scheme.
Example 3
In the example, the heating effect of different air inlet and outlet modes can be compared by calculating the distribution of the internal air temperature field under the heating condition, and the optimal design scheme from the ballastless track to the low-temperature test box is provided by the method.
Under the empty load condition of the test box, the air inlet speed is ensured to be certain, and the temperature distribution of indoor air is analyzed aiming at the temperature rising operation. In the case of temperature rise, the temperature is set at 70 ℃, and the air inlet speed is 1m/s. The following three air inlet and outlet modes are set, the heating time is set to be 1h, and the change of the indoor air temperature field of the experiment box along with the heating time under each air inlet mode is explored.
(1) Upper air inlet and lower air return: the air inlet and the air outlet are positioned on the same side of the test box body, and the air inlet is positioned above the air return opening;
(2) lower air inlet and upper air return: the air inlet and the air outlet are positioned on the same side of the test box body, and the air inlet is positioned below the air return opening;
(3) left air inlet and right air return: the air inlet and the air outlet are positioned at the opposite sides of the test box body and are positioned on the same horizontal plane.
The schematic diagram of each air inlet and outlet mode is shown in fig. 12.
Preliminary calculation shows that the temperature change trend and the amplitude of each node are basically consistent on each horizontal plane, which means that the air temperature at the same height in the box body is basically the same at the same time, so that only the air temperature change in the vertical direction is compared.
Fig. 13 is a schematic drawing showing the selection of horizontal planes at different heights in the vertical direction in a test box according to an embodiment of the present invention, fig. 14 is a schematic drawing showing the selection positions of No. 1 temperature nodes on horizontal planes at different heights in the test box, as shown in fig. 13 and 14, in order to intuitively see the change of air temperature in the vertical direction in the space of the test box, three horizontal planes, namely, an upper horizontal plane, a middle horizontal plane and a lower horizontal plane, are selected in the vertical direction, and a node No. 1 in the middle of the three horizontal planes is defined as an air top surface (D11), a vertical middle plane (D21) and an air bottom surface (D31) respectively.
Fig. 15 is a schematic diagram of a vertical air temperature gradient change curve when a heating mode of upper air intake and lower air return is adopted, as shown in fig. 15, according to an embodiment of the present invention.
Fig. 16 is a schematic diagram of a vertical air temperature gradient change curve when a temperature raising mode of lower air intake and upper air return is adopted, as shown in fig. 16, according to an embodiment of the present invention.
Fig. 17 is a schematic diagram of a vertical air temperature gradient change curve when a heating mode of left air intake and right air return is adopted, as shown in fig. 17, according to an embodiment of the present invention.
The above calculation shows that the temperature of the air in the test chamber is higher in the upper part and lower in the lower part. Compared with the heating modes of upper air inlet and lower air return, the heating rate of the air in the other two heating modes is greatly reduced, the heating time is 1h, and the bottom surface temperature only reaches 54.9 ℃ and 66.2 ℃.
In summary, under the condition of temperature rise, the air fluid in the box body is more uniform, and the temperature change uniformity performance of the test platform model is better by taking the rapid temperature rise and the temperature distribution uniformity of indoor air into consideration and adopting upper air inlet and lower air return as air inlet and outlet modes.
In summary, the high-speed railway ballastless track high-low temperature test platform designed by the method provided by the embodiment of the invention has the advantages of high visual degree, flexible modeling configuration and comprehensive design factor consideration, a system and a complete design method can be provided for the establishment of the high-speed railway ballastless track high-low temperature test platform, the early working problem of the test platform is solved, and the design method of the high-speed railway ballastless track test box is simple and feasible, high in visual degree and comprehensive in system.
The high-low temperature test platform for the ballastless track of the high-speed railway designed by the method is a multifunctional walk-in artificial environment composite simulation durability test device, has stable and balanced heating performance, can perform high-precision and high-temperature and humidity control, can simulate the service state of the ballastless track under the condition of real complex climate, is a large basic research and application basic scientific research test platform capable of carrying out comprehensive research and detection evaluation on structure scientificity, reliability and safety, and has the characteristics of commonality, universality, open sharing and the like.
The high-low temperature test platform of the ballastless track of the high-speed railway designed by the method can be used for carrying out structural fatigue test, structural temperature and humidity circulation test, ballastless track gap arching test, monitoring equipment and sensor performance test research, ballastless track surface coating technology test research, track disease treatment material/method related test, roadbed frost heaving and other related tests. In addition, the method can be applied to related tests and tests of various structures, components and equipment in other fields such as bridges, roadbeds, pavements, materials and the like.
Those of ordinary skill in the art will appreciate that: the drawing is a schematic diagram of one embodiment and the modules or flows in the drawing are not necessarily required to practice the invention.
Those of ordinary skill in the art will appreciate that: the components in the apparatus of the embodiments may be distributed in the apparatus of the embodiments according to the description of the embodiments, or may be located in one or more apparatuses different from the present embodiments with corresponding changes. The components of the above embodiments may be combined into one component or may be further split into a plurality of sub-components.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for apparatus or system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, with reference to the description of method embodiments in part. The apparatus and system embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (8)
1. The design method of the high-low temperature test platform of the ballastless track of the high-speed railway is characterized by comprising the following steps of:
establishing a high-low temperature test platform model of a ballastless track of a high-speed railway by using finite element software, wherein the high-low temperature test platform model comprises a test box library model, a test box base model, a working space fluid model and a ballastless track model, the test box library model is fixedly arranged on the test box base model, the working space fluid model is a fluid space which is not occupied by an object and needs to be heated or cooled in the test platform model, and the ballastless track model is fixedly arranged in the test box library model;
adjusting the component structure in the high-speed railway ballastless track high-low temperature test platform model according to the heat preservation effect, stability and applicability performance indexes of the high-speed railway ballastless track high-low temperature test platform model, and realizing the design and optimization of the ballastless track high-low temperature test platform;
an air inlet part model and an air outlet part model are arranged at the junction of the test box body model and the working space fluid model, and the air inlet part model and the air outlet part model are cube fluid space parts with the side length of 0.5 m;
establishing a space coupling heat transfer mathematical model of a high-speed railway ballastless track high-low temperature test platform by using finite element software, wherein the space coupling heat transfer mathematical model specifically comprises the following steps:
(1) The specific length, width and height dimensions of the high-low temperature test box body consider the elastic modulus, poisson ratio, density, expansion coefficient, heat conductivity coefficient and specific heat of the material;
(2) The specific length, width and height dimensions of the test box base take the elastic modulus, poisson ratio, density, expansion coefficient, heat conductivity coefficient and specific heat of the material into consideration;
(3) The working space fluid component is used for determining the size of an internal cuboid fluid space under the non-empty condition based on the size of a platform and a ballastless track structure for test paved in a test box, establishing the working space fluid component under the non-empty condition, and considering the density, expansion coefficient, thermal conductivity, specific heat and dynamic viscosity coefficient of air fluid;
(4) The air inlet and outlet component is set as a cube fluid space component with a certain size according to design requirements and is placed at the edge position of the platform box body, and the density, the expansion coefficient, the thermal conductivity, the specific heat and the dynamic viscosity coefficient of air fluid are considered;
(5) The ballastless track structure for the test is modeled by considering longitudinal constraints at two ends and considering the actual thermal conductivity material properties and geometric dimensions of the ballastless track structure.
2. The method for designing the high-low temperature test platform for the ballastless track of the high-speed railway according to claim 1, wherein the library plate of the library model of the test box adopts a three-layer structure of an inner container, a middle heat-insulating layer and an outer container, the inner container is made of stainless steel plates, the outer container is made of color steel plates, the middle heat-insulating layer is made of heat-insulating materials, and the inner container, the middle heat-insulating layer and the outer container are all simulated by adopting entity units.
3. The method for designing the high-low temperature test platform for the ballastless track of the high-speed railway according to claim 1, wherein the test box base model is in the form of a steel plate plus a concrete base or an integral concrete foundation structure and is positioned at the bottom of the test box base model.
4. The method for designing the high-low temperature test platform for the ballastless track of the high-speed railway according to claim 1, wherein the ballastless track model comprises steel rails, fastener units, track plates, mortar layers, supporting layers and wide and narrow joints, wherein the steel rails are simulated by beam units, the fastener units are simulated by spring units, the track plates, the mortar layers and the supporting layers are simulated by solid units, longitudinal restraint on the longitudinally connected ballastless track is realized at the restraint end part of the ballastless track model by arranging counterforce walls and jacks, the counterforce walls and the jacks are simulated by the solid units, and the pre-compression of the jacks is realized by heating jack parts.
5. The method for designing the high-low temperature test platform for the ballastless track of the high-speed railway according to claim 1, wherein the working space fluid model is used for calculating internal air temperature field distribution under the condition of heating and cooling, and the positions of the air inlet and the air outlet, the air inlet and outlet modes, the air inlet speed and the temperature set values are adjusted so as to meet the requirements of the test platform on heat preservation and insulation performance.
6. The method for designing the high-low temperature test platform for the ballastless track of the high-speed railway, according to claim 5, is characterized in that under the condition of the same thickness of the box body structure layer, the lower the heat conductivity coefficient of the heat preservation layer material, the larger the thermal resistance of the box body structure, the smaller the average heat conductivity coefficient of the box body, and the better the heat preservation and heat insulation performance of the test platform model.
7. The method for designing a high-low temperature test platform for the ballastless track of the high-speed railway according to claim 5, wherein when the test platform model performs a temperature-raising experiment, the air inlet and the air return are arranged on the same side of the test box body, and the air inlet is arranged above the air return.
8. The method for designing a high-low temperature test platform for a ballastless track of a high-speed railway according to any one of claims 1 to 4, wherein a top warehouse board of a test box body is a top board, a static analysis method is adopted to calculate vertical displacement of the top board under the condition of considering only structural dead weight, and the thickness of an inner structural layer and an outer structural layer of the top board is increased or a plurality of pairs of side supporting columns are arranged in a contrasting manner to support the test box body model so as to reduce the vertical displacement of the top board under the action of self gravity load.
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