CN110207915B - Dynamic response model and test method for ballast body and foundation bed - Google Patents
Dynamic response model and test method for ballast body and foundation bed Download PDFInfo
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- CN110207915B CN110207915B CN201910398897.0A CN201910398897A CN110207915B CN 110207915 B CN110207915 B CN 110207915B CN 201910398897 A CN201910398897 A CN 201910398897A CN 110207915 B CN110207915 B CN 110207915B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M7/00—Vibration-testing of structures; Shock-testing of structures
- G01M7/02—Vibration-testing by means of a shake table
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M7/00—Vibration-testing of structures; Shock-testing of structures
- G01M7/02—Vibration-testing by means of a shake table
- G01M7/025—Measuring arrangements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/18—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the time taken to traverse a fixed distance
- G01P5/20—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the time taken to traverse a fixed distance using particles entrained by a fluid stream
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/025—Geometry of the test
- G01N2203/0256—Triaxial, i.e. the forces being applied along three normal axes of the specimen
Abstract
The invention relates to a ballast bulk and foundation bed dynamic response model, which comprises a foundation bed, a first ballast layer, a second ballast layer, a sleeper and a track, wherein the first ballast layer, the second ballast layer, the sleeper and the track are sequentially paved on the foundation bed from bottom to top; magnets are embedded in the ballast particles in the first ballast layer; the device also comprises a magnetometer, wherein the magnetometer is used for tracking the movement track of the magnet along with the ballast particles; the test element is arranged on the filling soil of the foundation bed. The invention has the beneficial effects that: by special arrangement, tracking observation of the movement process of the railway ballast in the model in the flexible foundation bed and tracking observation of the stress state of the railway ballast and the foundation bed near the foundation bed are obtained, and the micro-mechanical behavior rule of the railway ballast sinking groove diseases is obtained.
Description
Technical Field
The invention relates to the field of bulk dynamics, fracture mechanics and road and railway engineering, in particular to a dynamic response model and a test method for a ballast bulk and a foundation bed.
Background
The micro-mechanics mechanism for the formation of the railway roadbed ballast bag and the railway ballast sinking groove diseases needs to be researched, the micro-mechanics behavior of the junction of the ballast track ballast and the bed under the action of dynamic load of a train needs to be researched, and the micro-mechanics behavior of the railway ballast particles and the bed can only be obtained through indoor similar model test observation.
The dynamic response relation of a ballast track subgrade and a ballast layer needs to obtain the distribution condition of stress, strain and displacement of the filler soil under the action of dynamic load, and the dynamic response relation of the ballast needs to obtain the behavior track distribution condition of a ballast on a certain section at the contact surface of the ballast and a foundation bed.
When the dynamic load numerical simulation calculation of the contact surface of the railway ballast and the bed is carried out, the acquisition of the physical and mechanical parameters of the railway ballast and the bed is very critical.
A design method of an indoor structure dynamic model test based on a similar theorem. The test model and the simulated prototype structure meet the physical and mechanical similarity, and need to meet the requirements of similar geometric dimension, similar stress-strain relationship, similar mass and gravity, and similar initial conditions and boundary conditions.
The dimensional analysis of the structural dynamic model test determines the relationship between the physical quantities, and the expression in the linear elasticity range is as follows:
f(σ,l,E,ρ,t,u,v,a,g,ω)＝0
λσ＝λE
λu＝λl
λ1＝lp/lm
wherein, σ, l, E, rho, t, u, v, a, g and ω are dynamic stress, length, elastic modulus, density, time, displacement, speed, acceleration, gravitational acceleration and circular frequency in sequence. The length l, density ρ and elastic modulus E are basically unknown. λ is defined as the similarity ratio of physical quantities between the prototype and the model. Lambda [ alpha ]l,λυ,λERespectively a geometric scale, a mass density scale and an elastic modulus scale.
λσ、λt、λu、λv、λa、λg、λwRespectively a stress scale, a time scale, a deformation scale, a speed scale, an acceleration scale, a gravity acceleration scale and a circle frequency scale. P, m represent prototype and model, respectively. The Cauchy constant, Froude constant are two important constants that are similar with respect to mass and gravity. The Cauchy constant or Froude constant is consistent with the prototype.
Law of similarity of gravity: the Froude constant reflects the requirement that the ratio of inertial force to gravity between the prototype and the model is equal, i.e. the gravity similarity law. The gravity similarity law can be used for researching the similarity relation of the adjacent destruction stages of the geotechnical buildings. The gravity similarity law requires that the Froude constant model be consistent with the prototype.
λg＝1
λσ＝λE，
λu＝λl，
λa＝λg＝1，
The rail is one of the main technical equipments of railway and subway, and is the foundation of running, it directly bears the load transferred from wheel, and transfers it to the buildings of road bed or bridge and tunnel, etc., and at the same time it also plays the role of guiding the rolling stock to smoothly and safely run. Ballast tracks are mostly adopted for heavy haul railways, and are characterized in that the ballast tracks are used as ballast bed structures of granular particles, and gaps always exist among ballast particles. The gap can lead the ballast particles to be mutually staggered and rearranged to be reduced due to the vibration of external load, and can lead the contact points (surfaces) of the ballast particles to be crushed and pulverized due to external pressure, thus leading the particles to be arranged more closely. Especially in the bridge and tunnel section, the off-line foundation is rigid and is higher than the track rigidity of the roadbed section, the railway ballast is more easily broken and polluted under the action of a heavy-duty train, the elastic buffering function of the railway bed is reduced, the impact between the wheel rails is aggravated, the maintenance difficulty and the workload are increased, and the railway bed in the tunnel and the bridge is easily damaged.
The dynamic characteristic test research of the railway ballast dispersion bodies has a plurality of research achievements at home and abroad, the indoor dispersion body dynamic characteristic model test usually comprises the steps of loading the railway ballast dispersion bodies on a rigid side wall, and then obtaining the movement, deformation and abrasion characteristics of the railway ballast in the rigid side wall through dynamic loading, and the method can only obtain the dynamic characteristic of the railway ballast as an independent research object and obtain related dynamic parameters. However, in the actual railway situation, the foundation bed for supporting the railway ballast is a flexible geotechnical structure, the contact surface of the railway ballast and the foundation bed can generate the mutual friction, mutual damage and mutual permeation under the action of train vibration load, the railway ballast sinking groove diseases of the ballast line are fully proved, and the interaction of the railway ballast sinking groove diseases at the contact surface is not comparable to that of the railway ballast and a rigid side wall.
With the rapid development of railway construction industry in China, it is very important to improve the construction quality of the roadbed to adapt to the crossing development of railways. The railway roadbed is an important component of railway engineering and is used as a geotechnical structure, the railway roadbed mainly comprises a foundation bed surface layer, a foundation bed bottom layer and a embankment below the foundation bed, and the settlement deformation of the roadbed is mainly generated by superposition of the settlement deformation of the foundation bed surface layer, the foundation bed bottom layer and the embankment below the foundation bed. The most of the built railways in China mainly comprise ballast railways, ballast railway subgrades are subjected to the action of cyclic accumulated loads to generate accumulated deformation in the long-term service process, and sleepers are subjected to the coupling action of vertical loads and horizontal loads caused by train running in the service process to possibly generate overlarge displacement so as to cause track failure. The accumulated deformation condition of the ballast layer of the ballast track under the long-term service condition is difficult to carry out detailed and comprehensive test tests on the site because the existing line subgrade can not be damaged, and the conventional road gate test box test for indoor tests can only carry out tests under the load of simple vertical or horizontal loads (such as snaking movement, train turning and the like) and can not simulate the influence of more complex mutual permeation between the two.
With the development of high speed passenger transportation and heavy freight transportation, the status of railway transportation in the transportation system becomes more and more important. And the track structure is as the basis of railway transportation, under the repeated action of train load, unfavorable defects such as fastener inefficacy, sleeper hang empty, inhomogeneous settlement of road bed often appear. The existence of these defects is very unfavorable for the safe operation of the train and greatly accelerates the fatigue damage of the track structure.
The attention of the dynamic response of the roadbed is focused on the dynamic coupling aspect of a train, a wheel track and the roadbed, the railway ballast is simulated into a spring or a damping, the damage of the railway ballast to the foundation bed is neglected, and the model test further recognizes the essential reason of the railway ballast sink-trough disease through the microscopic force research on particles at the contact surface of the foundation bed and the railway ballast.
The similar model test is an important research method in the field of mechanics, and is characterized by that it utilizes a certain proportion (similar proportion) to zoom the researched object, at the same time, the loading condition, boundary condition and material physical parameter also can be zoomed according to a certain similar proportion, then the parameters of stress, strain, displacement and void ratio of structure can be obtained and researched, and it has the advantages of influencing factor, controllable test condition and reliable test result.
With the rapid development of railway traffic in China, geotechnical engineering problems caused by traffic load are more and more emphasized by people. However, most of the current domestic traffic load indoor test methods are classified into two types, namely dynamic analysis of roadbed soil through a dynamic triaxial test; and secondly, simulating traffic load through a vibration test of the low-frequency servo loader. The two experimental principles are both simulation tests in a mode of simulating vibration waveforms of traffic loads, and the traffic load entity without similar model reduced scale is tested.
The geotechnical model experiment is widely used in geotechnical engineering. The observation of soil displacement and settlement is a main test parameter of geotechnical experiments, and the result is to analyze the main influence factors of soil stress distribution and the physical and mechanical properties of underground structures. The existing soil body displacement testing instrument aims at data measurement of engineering field experiments, has a large measuring range, and is used for directly reading experimental data in an indoor experimental environment, so that the indoor experimental data testing precision is low. The indoor model experiment test data is small, the test precision factor is ignored, and the instrument error causes the experiment test data to deviate from the experiment too much even the data is wrong. With the continuous development of computer technology and the advent of various commercial finite element software, the finite element method has rapidly developed and is used in various analyses, such as thermodynamic analysis, fluid mechanics analysis, mechanical part performance analysis, structural static and dynamic analysis, and the like. In many papers or patents in the prior art, a finite element model of a pile-plate structure roadbed of a high-speed railway is established, and dynamic response of the roadbed after pile-plate structure reinforcement under the action of dynamic load of a train is analyzed, wherein the dynamic load of the train is simulated by an excitation function formed by overlapping a static load and a sine function, or an 1/2 track-roadbed finite element discrete model is established by taking a longitudinal central line of a track as a boundary according to the symmetry of a railway track structure, and the influence of the speed of the train on the dynamic stress of the roadbed, the running quality of vehicles and dynamic displacement is analyzed by using the model. The method greatly promotes the development of the finite element model of the ballast track, but the method adopts full-solid modeling, so that the number of units is large, and the calculation efficiency cannot be ensured.
Disclosure of Invention
The invention aims to solve the technical problem of providing a dynamic response model and a test method for a ballast body and a foundation bed so as to overcome the defects in the prior art.
The technical scheme for solving the technical problems is as follows: a ballast body and foundation bed dynamic response model comprises a foundation bed, a first ballast layer, a second ballast layer, a sleeper and a track, wherein the first ballast layer, the second ballast layer, the sleeper and the track are sequentially paved on the foundation bed from bottom to top; the track is provided with two excitation points;
magnets are embedded in the ballast particles in the first ballast layer; the device also comprises a magnetometer, wherein the magnetometer is used for tracking the movement track of the magnet along with the ballast particles;
the test element is arranged on the filling soil of the foundation bed and is electrically connected with the data acquisition instrument.
On the basis of the technical scheme, the invention can be further improved as follows.
In the scheme, the ballast particles in the first ballast layer are made of regular tetrahedron stone.
In the above scheme, still include many test ropes, the one end of every test rope all is connected with the ballast granule in the first ballast layer, and the other end is the free end.
In the above scheme, the test element comprises a surface displacement meter, a soil pressure cell and a horizontal accelerometer, the surface displacement meter is arranged between the first ballast layer and the filler soil, and the soil pressure cell and the horizontal accelerometer are arranged in the filler soil in a layered mode.
In the above scheme, two waist plates of the upper-end open isosceles trapezoid box are made of transparent soft plastic plates, two interface plates of the upper-end open isosceles trapezoid box are made of transparent toughened plastic plates, and a bottom plate of the upper-end open isosceles trapezoid box is made of steel plates.
In the scheme, the ballast filling machine further comprises a camera, the camera is arranged on the periphery of the model box, and the collecting lens of the camera faces to an interface between the first ballast layer and the filling soil.
A test method for a dynamic response model of a ballast body and a foundation bed comprises the following steps:
The invention has the beneficial effects that: overcomes the limitation of understanding of the interaction of the rigid ballast body and the flexible bed by people, selects a proper vibration table for loading by establishing a small-scale indoor test model of the interaction of the small-scale ballast body and the flexible bed, by special arrangement, the tracking observation of the movement process of the railway ballast in the model in the flexible bed and the tracking observation of the stress state of the railway ballast and the bed near the bed are obtained to obtain the micro-mechanical behavior rule of the railway ballast sinking groove diseases, the law mainly comprises a stress change law, a strain change law, a movement track of the railway ballast in a foundation bed and the like, meets the treatment requirement of the railway maintenance field on the railway ballast sinking groove diseases, simultaneously verifies a numerical simulation calculation model established by the railway ballast for scientific researchers, in particular, a dynamic response analysis model of a wheel track-railway ballast-foundation bed (railway ballasts exist in an actual state) provides verification of test data.
Drawings
Fig. 1 is a first structural schematic diagram of a dynamic response model of a ballast dispersion and a foundation bed according to the invention;
FIG. 2 is a second schematic structural diagram of a dynamic response model of the ballast dispersion and the bed according to the invention;
fig. 3 is a third structural schematic diagram of a dynamic response model of the ballast dispersion and the bed according to the invention;
fig. 4 is a fourth structural schematic diagram of a dynamic response model of the ballast dispersion and the bed according to the invention;
FIG. 5 is a perspective view of the mold box;
FIG. 6 is a front view of the mold box;
FIG. 7 is a top view of the mold box;
FIG. 8 is a side view of the mold box.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.
As shown in fig. 1 to 8, a ballast body and foundation bed dynamic response model comprises a foundation bed 1, and a first ballast layer 2, a second ballast layer 3, a sleeper 4 and a track 5 which are sequentially laid on the foundation bed 1 from bottom to top, wherein the sum of the thicknesses of the first ballast layer 2 and the second ballast layer 3 is 10cm, the foundation bed 1 comprises a model box 110 and filler soil filled in the model box 110, the model box 110 is an upper-end open isosceles trapezoid box, the upper bottom of the upper-end open isosceles trapezoid box is 0.2m wide, the lower bottom of the upper-end open isosceles trapezoid box is 0.8m wide, the height of the upper bottom of the upper-end open isosceles trapezoid box is 0.3m long, the length of the upper-end open isosceles trapezoid box is 0.7m, a bottom plate 113 of the upper-end open isosceles trapezoid box is made of a rigid plate, preferably a steel plate material with the thickness of 2cm is used for simulating a fixed displacement boundary at the bottom of a railway foundation bed 1, two waist plates 111 of the upper-end open isosceles trapezoid box are made of a flexible plate, preferably a transparent soft plastic plate, the plastic plate has certain hardness and elasticity, and is allowed to deform under the action of proper load, so that the plastic plate and the actual railway embankment side slope can bulge outwards in a certain size under the action of long-term dynamic load, the concrete drainage ditch can generate certain cracks due to extrusion of soil, and therefore, the plastic plate is suitable for simulating the embankment side slope of the railway roadbed by adopting a flexible boundary, two boundary plates 112 of the isosceles trapezoid box with an open upper end are made of semi-rigid plates, and the plastic plate is preferably simulated by adopting transparent toughened glass with good hardness and rigidity and 3 cm-6 cm in thickness, so that the purpose of simulating the cross section of the model box 110 into a fixed displacement boundary is achieved, and the plastic plate is basically consistent with the actual state of the railway. The model box 110 was frequency analyzed using ABAQUS software.
The sleeper 4 adopts the thin steel wire concrete piece of certain scaling proportion, and the intensity of concrete piece reaches more than C30, and track 5 adopts the processing steel sheet, adopts the processing nut to be connected between track 5 and the sleeper 4, places the sleeper 4 who will process on second ballast layer 3 to fix it on second ballast layer 3 with the iron wire, when preventing the excitation test, take place the dislocation of track 5.
The rail 5 is provided with double excitation points 510, the connecting line of the positions of the double excitation points 510 is a symmetrical line of the model, proper vibration loading equipment is selected according to the size of the model and the arrangement of the excitation positions, or the vibration loading equipment is specially set according to the size of the model to meet the special requirement of fixed loading of the model, the test adopts a double excitation loading mode, the dynamic load spectrum adopts a plurality of statistical spectrums of field test of the Solomon railway, the average fitting and the outer envelope fitting are respectively carried out on the plurality of field test statistical spectrums of two parallel rails 5, further the average fitting dynamic load time course curve and the outer envelope fitting dynamic load time course curve of the two parallel rails 5 are respectively obtained, the average fitting spectrum and the outer envelope spectrum on the two rails are initially determined in a certain proportion of 1:10 for scaling on the amplitude according to the loading principle of a similar model test, and the performance parameters of the test equipment of the vibration table are combined, and (3) carrying out cycle adjustment of a time-course curve and elimination of partial high-amplitude time points, so that double excitation loading of an outer envelope spectrum and an average spectrum of a similar test model can be realized, three rows of excitation positions are arranged at intervals of 20cm, and the excitation size distribution positions are shown in figure 6.
And (3) drilling and processing the ballast particles in the first ballast layer 2, placing magnets in the ballast particle holes, and sealing the holes with gypsum after the magnets are placed. The track device further comprises a magnetometer, and the movement track of the ballast particles in the first ballast layer 2 under the action of the vibration load can be obtained by tracking the magnets in the ballast particles through the magnetometer. Drilling a pore with the diameter of 1-2 cm, preferably 1cm, on the outside of the ballast particles, tying the particles together by using a test rope, reserving the rest length of 7-8 cm, preferably 8cm, namely, one end of each test rope is connected with the ballast particles in the first ballast layer 2, the other end is a free end, the test rope is preferably red wiring, after the test, the ballast particles which are not penetrated into the filler soil in the first ballast layer 2 are stripped, the total displacement of each ballast particle in the first ballast layer 2 on the foundation bed 1 can be obtained by measuring the length of the test rope on the ballast particles immersed in the filler soil, the movement rate of the ballast particles immersed in the foundation bed 1 can be obtained through the relationship between the displacement and the time, and obtaining relevant experimental parameters such as a displacement distribution diagram, a speed distribution diagram, a motion track distribution rose diagram and the like of the whole foundation bed 1 surface and the ballast particles immersed in the foundation bed 1 through statistics.
Preparing and treating ballast particles in the first ballast layer 2: the preparation and treatment of the ballast particles in the first ballast layer 2 are one of the keys of successful tests, the ballast particles have the hardness equivalent to that of the actual ballast on site, the actual ballast proportion is scaled according to the size of the ballast particles in a ratio of 1:6, the ballast particles are processed into uniform regular tetrahedrons, the side length of the bottom edge is 1cm, the height of the bottom edge is 1cm, the material is selected from medium-slightly weathered granite or rocks and materials with similar hardness and rigidity, and the ballast particles in the second ballast layer 3 only need to be processed into the regular tetrahedrons.
The dynamic response model of the ballast body and the foundation bed further comprises a test element 6, and the test element 6 is arranged on the filler soil of the foundation bed 1. The test element 6 comprises a surface displacement meter 610, a soil pressure box 620 and a horizontal accelerometer 630, wherein the surface displacement meter 610 is arranged between the first ballast layer 2 and the filler soil, the soil pressure box 620 and the horizontal accelerometer 630 are arranged in the filler soil in a layered mode, preferably, the soil pressure box 620 is arranged in the vertical direction and the horizontal direction at the position where the vibration excitation position is symmetrical, so that the change relation of the soil pressure of the model under the action of vibration load along the vertical direction and the lateral direction of the deep position where the vibration excitation point is symmetrical is obtained. Preferably, horizontal accelerometers 630 are arranged at symmetrical positions along the connecting line of the excitation positions along the depth, so that the dynamic response of the foundation bed 1 under the coupling action of the vibration load-the ballast-the foundation bed 1 is obtained, the test element 6 can respectively measure the vertical displacement and the horizontal displacement of the surface of the foundation bed 1, and the relation between the surface displacement and the position of the excitation point is obtained, the relation comprises the relation between the horizontal and vertical aspects, the embedding of the test element 6 fully utilizes the symmetry of the whole model and the loading, the similar elements only need to be embedded in 1 of the four areas, the relevant parameters of other areas can be obtained by calculating the symmetric conditions, two filling soils are selected in the model test, one is to simulate the foundation bed 1 into a weak-caking discrete structure, the microscopic behavior of the interaction between the first ballast layer 2 and the filling soil at the contact surface is simulated into the mutual extrusion and permeation process of coarse and fine particles with different compactedness under the action of vibration load; the flexible continuous medium is simulated to have strong cohesiveness, and the mesomechanics behavior of the interaction between the first ballast layer 2 and the contact surface of the filler soil is simulated to be the extrusion damage process of the rigid ballast to the flexible continuous medium under the action of vibration load, wherein the former belongs to the bulk mechanics behavior, and the latter belongs to the fracture mechanics behavior of the continuous medium.
Preparing and treating the filling soil: before the formal test, the geotechnical test of the filling soil is carried out, and the related physical and mechanical parameters of the undisturbed filling soil are obtained and used as the reference basis for the preparation of the similar test model soil. According to the shape of the bed filling of the plastic railwayIn the case of the method, the filler soil is divided into strong-cohesive soil and weak-cohesive soil, wherein the former has more clay components and stronger viscosity; the latter clay has less components and weak viscosity, and the filler soil mainly comprises the following components: deformation modulus E, cohesive force c and internal friction angle of soil body
The soil density rho, the compressive strength, the percentage of each particle composition (clay, powder, silt, fine sand, medium sand, coarse sand and gravel), and the physical mechanical parameters and the particle components of the representative undisturbed filler soil of the foundation bed 1 obtained by a large number of physical mechanical tests are respectively shown in tables 1 and 2:
TABLE 1 two kinds of physical and mechanical parameters of undisturbed filling soil
TABLE 2 percentage of each component of two types of undisturbed filling soil
And the similarity criterion selects 3 independent basic quantities according to a second similarity theorem, obtains the number of dimensionless factors, determines the similarity relation of the structural model by applying a dimension analysis method through the fact that the model and the prototype are in the same gravitational field and the gravity acceleration is equal, and further determines the similarity relation of all parameters, wherein the geometric similarity ratio selected by the model is 4. The preparation of the model test filler soil refers to two types of actual physical and mechanical parameters of the filler soil to carry out design calculation according to a certain similarity criterion. Including the intensity similarity ratio CσSevere similarity ratio CγAnd the geometric similarity ratio satisfies the relation Cσ＝CγC. According to the above-mentioned similarity relationship, the preparation of filling soil can be implemented. The filler soil is selected to meet the general principle of material selection, and mainly has proper strain value and displacement value under the condition of a test load member, and the filler soil reaches the compactness required by railway design specifications, and a sampling pair is adoptedThe bed 1 is subjected to common triaxial experiment test, resonance column test and dynamic triaxial test to obtain a dynamic relation curve of experimental materials of the bed 1. The prepared filler soil is prepared from clay, silt, fine sand, medium sand, coarse sand and gravel according to the actual component proportion of the two types of foundation bed filler soil, barite powder, engine oil and water are added, the mixture is uniformly mixed according to a certain proportion, then the mixture is pressurized and stands for a period of time, and the artificial filler soil with relatively stable performance is obtained. The purpose of the test is to analyze the microscopic influence of the ballast in two types of foundation bed (1) modes, and the performance parameters of the two types of filler soil are shown in table 3:
TABLE 3 two types of Filler soil Performance parameters
The railway ballast bulk and foundation bed dynamic response model further comprises cameras, the cameras are arranged on the periphery of the model box 110, the cameras usually adopt high-power cameras, and the acquisition lenses of the cameras face the interface between the first ballast layer 2 and the filler soil, and because the periphery of the model box 110 is transparent, when a vibration model test is carried out, the whole dynamic process that railway ballast particles in the first ballast layer 2 at the interface invade the filler soil can be recorded through the high-power cameras, so that the success of the model test is very necessary.
Data acquisition and processing: the data acquisition instrument is adopted to read the test data, and the universal data acquisition instrument can realize the functions of real-time reading, modularized reading, wireless acquisition and the like of a network. The invention realizes the processing of high-frequency mass data by establishing a real-time data acquisition instrument for acquiring data, including the functions of time interval averaging, invalid data elimination and various curve drawing and comparison, and realizes the database management functions of multiport webpage database management, including database data updating, real-time processing, random calling and the like by compiling a database management system through a webpage browser through the internet database management technology.
A test method for a dynamic response model of a ballast body and a foundation bed comprises the following steps:
step 1: designing and manufacturing a model: according to the theory related to the similar test, the geometric dimensions of a model box and a model are determined, a bed simulation material and a railway ballast material which are suitable for the actual railway bed and railway ballast are obtained through the test, filling soil is filled in the model box in a layered mode, the compaction degree is used as a control index, test elements 6 are arranged on the surface or arranged in a layered mode according to the symmetry principle, railway ballast particles in a first railway ballast layer 2 are arranged in a certain sequence, the thickness of the first railway ballast layer 2 can be properly increased at the excitation position, the railway ballast particles in a second railway ballast layer 3 can be randomly arranged, and the fact that the influence of the second railway ballast layer 3 on the dial plate of a surface displacement meter 610 is minimum in the test process is guaranteed;
step 2: debugging: debugging a test element 6, a data acquisition instrument, a camera, vibration loading equipment and a magnetometer, mainly comprising the steps of reading initial data, setting module data reading frequency, wirelessly transmitting, acquiring in real time, transmitting in real time, debugging the function of storing in real time and debugging the resolution of the camera, wherein the camera is used for observing the mutual permeation process of a first ballast layer 2 and a foundation bed interface at the edge of a model under the action of vibration load, and debugging the vibration loading equipment, comprises the average fitting and the outer envelope fitting of a plurality of actual measurement dynamic loads, obtaining the accurate dynamic load loads by loading spectral analysis on vibration platform testing equipment, debugging the magnetic tracking resolution of ballast particles with magnets by the magnetometer, tracking and scanning the tracks of the ballast particles in part of the first ballast layer 2 under the action of the vibration load, and scanning the magnetometer in real time, real-time transmission and real-time analysis of the motion trail of the ballast, and debugging the stability of the functions;
and step 3: and (3) testing: continuous vibration loading is carried out on the model double excitation points 510, the corresponding relation between the acquired data of the test element 6 on the foundation bed 1 and the dynamic load spectrum is obtained in real time, the deformation conditions of the flexible boundary and the rigid boundary are tested, a camera is utilized to record the flexible boundary, the moving image of the railway ballast is marked, meanwhile, the moving track of the railway ballast particles with the magnets is tracked through a magnetometer, and the distribution condition of the railway ballast moving track at a certain section of the roadbed can be obtained through analyzing the running track of the railway ballast particles with the magnets; when the experiment is carried out to a certain degree, a data acquisition instrument is started to read data, and data are acquired by setting data acquisition frequency and multiple groups of data in each time period and utilizing a wireless network transmission technology in different time periods to carry out corresponding data processing, so that the data amount required to be processed can be reduced;
and 4, step 4: the real-time data processing module receives real-time monitoring data of the front-end data acquisition module through a wireless network transmission channel, is equivalent to a rear-end monitoring sub-block of a general data analysis system, realizes data analysis, processing and curve display through a built-in program, can be opened on a background computer in a browser mode through logging user authority, realizes remote control of the whole test process, realizes identification of error data through compiling abnormal data standards, can realize real-time data processing through presetting average processing data number, and can also be changed in real time through manual operation; various monitoring parameters real-time monitoring curves are realized by presetting monitoring sections; by setting real-time comparison of response parameters, drawing a parameter response comparison curve; it should be noted that: the curve drawn by the real-time data processing module is rough and only provides a basis for experimenters to master the test process, and data needs to be exported to obtain an attractive data curve, and the data is realized by means of third-party software;
and 5: simulating the process of an indoor similar model test through a discrete element analysis model, respectively establishing a railway ballast-bed (coarse-fine) particle discrete element dynamic response analysis model and a particle discrete element-continuous medium finite element coupling calculation analysis model according to two types of bed materials, simulating the geometric dimension with a similar test 1:1, and carrying out boundary conditions: the inclined side wall adopts a flexible boundary, the section wall and the bottom wall adopt a rigid boundary, the dynamic load simplifies the actual test dynamic load spectrum into a plurality of standard dynamic loads, and then the dynamic loads are superposed according to the superposition principle.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (7)
1. The ballast body and foundation bed dynamic response model is characterized by comprising a foundation bed (1), and a first ballast layer (2), a second ballast layer (3), a sleeper (4) and a track (5) which are sequentially paved on the foundation bed (1) from bottom to top, wherein the foundation bed (1) comprises a model box (110) and filler soil filled in the model box (110), the model box (110) is an isosceles trapezoid box with an open upper end, and two waist plates (111), two boundary plates (112) and a bottom plate (113) of the isosceles trapezoid box with the open upper end are respectively made of flexible plates, semi-rigid plates and rigid plates; the track (5) is provided with double excitation points (510);
magnets are embedded in the ballast particles in the first ballast layer (2); the device also comprises a magnetometer, wherein the magnetometer is used for tracking the movement track of the magnet along with the ballast particles;
the test bed further comprises a test element (6) and a data acquisition instrument, wherein the test element (6) is arranged on the filling soil of the bed (1), and the test element (6) is electrically connected with the data acquisition instrument.
2. The ballast body and foundation bed dynamic response model according to claim 1, wherein the ballast particles in the first ballast layer (2) are made of regular tetrahedron stone.
3. The ballast body and foundation bed dynamic response model according to claim 1, further comprising a plurality of test ropes, wherein one end of each test rope is connected with ballast particles in the first ballast layer (2), and the other end is a free end.
4. A ballast dispersion and foundation dynamic response model according to claim 1, wherein the test element (6) comprises a surface displacement meter (610), a soil pressure cell (620) and a horizontal accelerometer (630), the surface displacement meter (610) being arranged between the first ballast layer (2) and the filling soil, the soil pressure cell (620) and the horizontal accelerometer (630) being arranged in layers within the filling soil.
5. The ballast body and foundation bed dynamic response model as claimed in claim 1, wherein the two waist plates (111) of the upper end open isosceles trapezoid box are made of transparent soft plastic plates, the two boundary plates (112) of the upper end open isosceles trapezoid box are made of transparent toughened plastic plates, and the bottom plate (113) of the upper end open isosceles trapezoid box is made of steel plates.
6. The ballast body and foundation bed dynamic response model according to claim 5, further comprising cameras, wherein the cameras are arranged around the model box (110), and the collecting lenses of the cameras face the interface between the first ballast layer (2) and the filling soil.
7. A test method for the dynamic response model of the ballast dispersion body and the bed according to any one of claims 1 to 6, characterized by comprising the following steps:
step 1, model design and manufacture: constructing a scaled model according to the relevant theory of the similar experiment;
step 2, debugging: debugging the test element (6), the data acquisition instrument, the camera, the vibration loading equipment and the magnetometer;
step 3, testing: the method comprises the steps of continuously vibrating and loading a model double-excitation point (510), acquiring a corresponding relation between acquired data obtained by a test element (6) and a dynamic load spectrum in real time through a data acquisition instrument, recording deformation conditions of a model box (110) and marking moving images of ballast particles in a first ballast layer (2) through a camera, tracking a moving track of the ballast particles with magnets through a magnetometer, measuring the length of a test rope on the ballast particles immersed in the filling soil to obtain the total displacement of the ballast particles in a foundation bed (1), obtaining the moving rate of the ballast particles immersed in the filling soil in the foundation bed (1) through the relation between the displacement and time, and counting to obtain relevant experimental parameters of the ballast particles immersed in the filling soil.
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| CN111563287B (en) * | 2020-03-24 | 2023-01-06 | 中铁隧道集团二处有限公司 | Vertical curve jacking pipe jacking force estimation method based on segmented displacement control method |
| CN111797459B (en) * | 2020-07-21 | 2023-10-24 | 北京交通大学 | Construction method of ballasted track-bridge dynamic coupling model |
| CN116735151A (en) * | 2023-08-10 | 2023-09-12 | 西南交通大学 | Particle motion trail monitoring system based on magnetic positioning and positioning method thereof |
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| JP3050486B2 (en) * | 1994-04-25 | 2000-06-12 | 東海旅客鉄道株式会社 | Ballast condition inspection device for shoulder |
| CN102108656B (en) * | 2010-12-18 | 2012-05-09 | 浙江大学 | System for kinetic model test of ballastless track subgrade of high-speed railway |
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