RU2380472C2 - Method for comprehensive analysis of railway subgrade - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: railway subgrade analysis comprises preliminary processing of available data to disclose abnormal sections and select control drilling points and additional geo-radiolocation profiles. Geo-radiolocation analysis allows isolating layers with different dielectric factors. Drilling is performed in not only within disclosed abnormal zones but also on every kilometre of analysed section. Track bed is manually drilled to obtain data on broken stone layer properties, particle sizes and lithology, mechanical grading, moisture content, density and soil solid-to-liquid ratio. Data obtained are interpreted to plot them onto exaggerated longitudinal track section.

EFFECT: higher efficiency of analysis, reduced railway repair costs, repair materials savings.

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Description

The invention relates to the field of inspection of railways, roads and routes of linear structures, in particular to assessing the condition of objects of the subgrade and ballast layer, as well as the foundations of the routes of structures with a combination of geophysical - georadiolocation and engineering-geological methods and presenting the obtained data in the form of a geological section plotted on the exaggerated longitudinal profile of the path.

The known method of subsurface radar described in the article S. Izyumova and others. - Survey of the subgrade by Geoscope. - Way and track facilities, 2006, No. 6. - p. 36. For several years, Geologorazvedka LLC and FGU 61 NIIII (ZhDV), the Ministry of Defense of the Russian Federation, have been developing a railway track monitoring system (SMPZD) in order to search for mines and explosive objects. The created system made it possible to solve not only purely military tasks, but also to use it to inspect the railway bed, including with the aim of determining the thickness and topography of the main layers of ballast materials and soils, clarifying the location of troughs, bags, etc., identifying water lenses or places of local waterlogging of the soil. This article discusses some examples of surveying the subgrade using the Geoscope radar system. The monitoring system for the railroad track includes an electromechanical trolley made of a dielectric, and nodes of the Geoscope. The operation of GPRs in this series is based on the emission of a geomagnetic video pulse with a wide spectrum and registration of video pulses reflected from inhomogeneities. Separate antennas are used to receive and transmit signals.

The processing results of such signals allow constructing the image results of the reflecting boundaries of various inhomogeneities of the sensing medium, including ballast and subgrade layers. The processing program builds an image in the form of a vertical section of the soil.

The disadvantage of this method is that geophysical data are not confirmed by control drilling, and boreholes, in turn, are located only according to visual inspection, which leads to a decrease in the efficiency of survey of the subgrade, and sometimes to an increase in the cost of time and money as in the field period, and for desk processing of materials. Materials are presented in the form of separate engineering-geological sections or radarograms, which creates inconvenience to both designers and engineers of organizations performing further work on projects.

The multichannel georadar complex is presented in the article by V.I. Kolesnikov, V. B. Vorobiev, V. A. Yavna, A. B. Kireevnin, V. V. Pomozov, A. V. Dudnik. - GPR diagnostics of the path. Way and track facilities. 2007, No. 3, pp. 19-21.

The complex is designed to diagnose objects of the subgrade of the railway track. Inspection along the axis and roadsides is carried out simultaneously by three antennas operating in continuous mode. The radar is moved along the profile by MPT-4 railcar at a speed of 70 km / h. A distinctive feature of the complex is the ability to receive signals in antenna units not only from its own transmitting antenna, but also from an adjacent transmitting antenna. The ability to simultaneously receive signals from one transmitter to two spaced receivers allows you to determine the speed characteristics of the layers for a more accurate determination of depths.

Disadvantages: the result of using this method is a radarogram, which in itself does not carry almost any information to the railway engineer, while the exaggerated longitudinal profile of the track is familiar to every road foreman and it’s much more convenient to work with geological data made on a basis familiar to railway workers, than with separate geological sections or radarograms.

A known method of non-contact inspection of the profile of crushed stone ballast base in the description of the application for the invention No. 2250283, IPC 7 ЕВВ 35/00, В61К 9/08 from 2003.11.10, published 2005.04.20, passing perpendicular to the longitudinal direction of the rail track, characterized in that the examination occurs in parallel with the determination of defects according to the level of the path, and when determining their location and depending on the registered defects according to the level and respectively obtained for this ballast base profile, the amount of crushed stone necessary for raising his way to a predetermined level and for its uniform ballasting.

2. The method according to claim 1, characterized in that to determine the amount of crushed stone required for the ballast base, a registered profile of the ballast base is imposed on a given cross-sectional profile.

3. The method according to claim 1 or 2, characterized in that the required amount of crushed stone is calculated, and then the information contained in the storage device is overwritten separately for the left or right half of the path.

Disadvantages: the information does not reflect the true condition of the subgrade, only the contour of the ballast prism is examined.

The closest known analogues is the method of examination of the subgrade, described in the article Trenin VV, Ershova EV - The use of georadar subgrade. - Way and track facilities. 2007, No. 8, p.29. In complex areas, to obtain more objective continuous information about the structure of the section, a georadar survey was used. To do this, use the Zond-12e georadar equipped with a shielded antenna with a frequency of 750 MHz operating in isolation from the surface of the probed medium. Radar inspection is performed continuously. The antenna is carried along the axis of the path or along the edge of the subgrade. As the antenna moves, the signal in the form of a radar profile is reflected on the laptop screen with the installed Prism-2 software package, with the help of which all the Zond-12e georadar is controlled. Snapping to pickets is done on the radarogram manually with markers. In addition, they also mark the beginning and end of excavations, swamps, and the axis of artificial structures. All this subsequently helps to interpret the GPR. After the sounding of a certain section of the path, the profile is recorded on the laptop hard drive. At the next stage, sections of the profile with a useful signal, tied to the picket, are correlated with the drilling data of reference wells, while plotting the boundaries of the soil layers. The result is a continuous geological section.

The disadvantages of all of the aforementioned analogues is that each method is used separately, independently of each other - geophysical data are not confirmed by control drilling, and boreholes, in turn, are located only according to visual inspection, which leads to a decrease in the efficiency of survey of the subgrade, and sometimes to increase the time and money spent both on the field period and on desk processing of materials. Materials are presented in the form of separate engineering-geological sections or radarograms, which creates inconvenience to both designers and engineers of organizations performing further work on projects.

The technical result of the proposed method is to increase the efficiency of the survey of the subgrade, reducing the cost of repairs and more economical spending of building materials.

The technical result of this invention is achieved due to the fact that the method of a comprehensive survey of the subgrade of railways, including non-contact, georadar inspection, drilling, registration of defects, analysis of the state according to the measured parameters, transferring the received data to the cross section of the subgrade, differs in that the inspection The subgrade of the railway is carried out comprehensively, sequentially with pre-processing and analysis of the materials obtained to identify mal portions and destination control points drilling and other geo-radiolocation profiles, and drilling is carried out not only within the identified anomalous zones, but also on every kilometer of the subject portion. Drilling is carried out using a manual drilling kit along the ballast layer with a description of crushed stone contamination, size of fractions and lithology, with a description of particle size distribution, humidity, density, soil consistency, while the results of the measurements are interpreted to transfer the obtained data to an exaggerated longitudinal path profile.

The GPR survey is carried out by the ZOND-12E GPR, profiling is performed at the ends of the sleepers and is carried out continuously with virtually any sounding density, at the stage of preliminary processing of the GPR data in the field, the interface between media with different dielectric constants is distinguished, a high-speed model is built, the identified model is decrypted, and the identified abnormal zones, according to the results of processing, boreholes are laid. The results of the measurements are interpreted in order to transfer the obtained data to an exaggerated longitudinal path profile. Improving the effectiveness of the survey of the subgrade is achieved due to the fact that, unlike analogues in the claimed invention, the structural elements of the subgrade: ballast prism, embankment core, base of the embankment are examined by a set of engineering-geological and geophysical methods in strict sequence, with identification of changes in the configuration of the main subgrade site canvas - ballast trough, bed, bags, nests, others, with the definition of pollution, ballast power and sand cushion, with a description of particle size distribution eskogo composition, humidity, density, soil consistency. With such a comprehensive survey, data is obtained on the state of each structural element of the subgrade and on the site as a whole. The use of the georadar method in combination with drilling allows, in addition to lithological partitioning of the section, to more accurately determine the propagation velocity of electromagnetic waves in the medium under study, and therefore, more accurately recalculate from a temporary section into a deep section, and obtain information about the configuration of geological and lithological layers and the structure of the subgrade between wells, to record in detail all changes in the configuration of the main platform of the subgrade - trough, bed, bags, nests, etc. All of the above When using only one georadiolocation method, the data obtained are obtained with large errors.

Due to the complex sequential execution of work in this method, the efficiency of the survey of the subgrade is increased, the cost of repair work is reduced and construction materials are spent more economically. Improving the effectiveness of the survey of the subgrade is achieved due to the fact that, unlike analogues in the claimed invention, the structural elements of the subgrade: the ballast prism, the core of the embankment, the base of the embankment are examined sequentially, comprehensively with the identification of changes in the configuration of the main platform of the subgrade - trough, bed, bags, nests, other pollution, ballast power and sand cushion. The contamination of the ballast and its filtration capabilities, siltation or failure of various drainage structures, together with other factors, leads to deformations of the main site of the subgrade, slopes of embankments and excavations, which, in turn, lead to the destruction of the track’s upper structure, which makes it necessary to constantly monitor the condition of the subgrade. Using the georadar method in combination with drilling allows you to more accurately determine the propagation velocity of electromagnetic waves in the medium under study, and therefore, more accurately calculate the depth of the interface between media with different dielectric constants, decrypt the anomalous zones identified during the preliminary processing of georadar data in the field, and also make a layered description of the ballast prism, necessary to justify design decisions for cutting or cleaning bnya. When using one method of georadar, the above data can be obtained only with a high error, and the use of only one drilling leads, firstly, to an increase in drilling volumes, and secondly, to inaccurate correlation of geological layers.

Reducing the cost of field work is achieved due to the fact that drilling work is carried out only after preliminary processing of georadar data, which allows more efficient determination of the location of drilling wells and contouring local heterogeneity of the subgrade, as well as significantly reducing the amount of drilling work. After a qualitative and quantitative interpretation of geophysical materials and processing of drilling data, the results of these two methods are transferred to an exaggerated longitudinal path profile, which significantly increases the information content of this profile and reflects a more complete picture of the condition of the subgrade. This information allows designers to make more informed decisions on the depth of gravel cutting, replacing or cleaning the ballast layer, laying and choosing the type of separation layer of non-woven material, etc., which, in turn, leads to more efficient consumption of building materials and lower costs for repair work.

In comparison with analogues, this complex includes a number of sequentially, comprehensively performed survey stages of the subgrade:

- visual inspection;

- georadar inspection

- pit drilling and well drilling;

- analysis of the state according to the measured parameters;

- transfer of the received data to an exaggerated longitudinal track profile.

Visual inspection is one of the methods of examination for quality characteristics, which include:

- cracks on slopes, shoulders, at the ends of sleepers, etc.

- the presence of splashes of liquefied ballast in inter-sleepers;

- the presence of abyssal humps;

- the presence of soil blockage in the bottom of the slopes;

- distortion of the outlines of slopes of embankments and excavations;

- the slope of the supports of the contact network;

- the presence of karst and suffusion funnels on the elements of the subgrade;

- water exit from the body of the subgrade or its base, etc.

Based on the results of a visual inspection of the subgrade, local deformable areas are identified and the optimal set of instrumental measurement methods is selected: georadar and drilling.

GPR survey is carried out by a team consisting of a geophysicist engineer, an auxiliary worker and two signalists. In this case, the ZOND-12E georadar is used. GPR survey is performed by a complex of hardware and software. The method of georadar inspection is based on the emission of electromagnetic waves into the test medium, reception, processing and display of electromagnetic waves reflected from the boundaries of soil layers with different electrophysical properties - dielectric constant, conductivity, density, etc. - in the form of radarograms.

Figure 1 shows a fragment of a radarogram, which is a vertical wave profile, on the horizontal axis of which the X coordinate is plotted along a section of the railway - either in meters or in tracks; either the transit time of the electromagnetic wave in the -ns- medium or the depth in meters is plotted from top to bottom on a vertical axis, if time is recounted in depth. As a result of cameral processing, layers with different dielectric constants are distinguished by the nature of the wave pattern. Three layers are distinguished in this figure: ballast - in this case crushed stone, position 1; sand cushion and soil of the embankment core - in this case represented by sand, pos. 2, 3; soil base embankment, pos.4.

Using georadar inspection, the following parameters are identified:

- determination of the power of the ballast layer;

- identification of places of accumulation of mud nests or lenses in the thickness of the ballast prism, leading to the development of splashes;

- determining the configuration of the main site of the subgrade, and the configuration and the depth of the distribution of irregularities of the main site can predict the presence of such deformations as ballast troughs, bags, nests, etc.

- identification of voids in karst areas at the base of the subgrade.

After performing georadar measurements, the geophysicist and geological engineer carry out joint preliminary processing and interpretation of the materials obtained in order to identify abnormal areas and designate drilling control points and additional georadar profiles.

At the next stage of work, a team consisting of a geological engineer, a drilling foreman and two auxiliary workers performs control drilling. The location of the wells shown in figure 2. In this case, a fragment of the transverse profile of the subgrade is shown, represented by an embankment 3.5 m high with absolute elevations of the rail heads and bends of the profile. Four layers were opened by boreholes 26 and 27: ballast-crushed stone - 1; sand cushion, represented by medium-grained sands of low degree of water saturation, with the inclusion of pebbles up to 15-20%, 2; soils of the embankment core, represented by sandy loam of plastic consistency, 3; soils of the base of the embankment, represented by loams of a refractory texture, 4.

Well drilling is carried out with a manual drilling kit in two stages:

- at the first stage, a pit is drilled along the ballast layer, contamination of crushed stone, size of fractions and lithology is described, the layer is cased;

- at the second stage, a well is drilled with a description of lithology, particle size distribution, humidity, density, and soil consistency.

After carrying out all instrumental measurements, the geological engineer and geophysicist engineer processes and interprets all the materials obtained, compiles the geotechnical characteristics of the site, the borders highlighted on radargrams are exported using AutoCad software to create a geological section superimposed on an exaggerated longitudinal path profile . GPR is used in combination with well drilling, while the volume of drilling is reduced by 3-4 times, which entails a reduction in the timing of field work, and since GPR is one of the methods of non-destructive testing, the effect of drilling on the condition of the subgrade is it is minimized.

Thus, the survey result is a geological section, first brought to the exaggerated longitudinal profile of the track of figure 3, which allows a comprehensive assessment of the condition of the subgrade of the railway. In the claimed invention, for the first time, the results of the survey of the subgrade of the railway in the form of a geological section are taken out on the exaggerated longitudinal profile of the track, which makes it possible to comprehensively assess the condition of the subgrade of the railway track, increase the efficiency of the survey of the subgrade, reduce the cost of repair work and use building materials more economically.

A comparative analysis of the proposed solutions with the prototype allows us to conclude that the claimed method differs from the known analogues: a set of essential distinguishing features:

- the implementation of a set of works on the survey of the subgrade in the complex, where:

- after a visual examination is carried out

- GPR work, and only then do:

- control drilling.

The result of the complex of works is:

- a vertical section, first brought to the exaggerated longitudinal path profile.

Comparative analysis with the prototype allows us to conclude that the claimed method meets the criterion of "novelty."

The claimed invention is illustrated by drawings, where:

Figure 1 shows a fragment of a radarogram, which is a vertical wave profile, on the horizontal axis of which the X coordinate is plotted along a section of the railway track - either in meters or in tracks, the transit time of the electromagnetic wave in the ns medium is delayed from top to bottom, or depth in meters, if time is recounted in depth. As a result of cameral processing, layers with different dielectric constants are distinguished by the nature of the wave pattern. Three layers are distinguished in this figure: ballast (in this case, crushed stone) 1; sand cushion and soil of the embankment core (in this case, represented by sand) 2, 3; soil base embankment 4.

In figure 2. in this case, a fragment of the transverse profile of the subgrade is shown, represented by an embankment 3.5 m high with absolute elevations of the rail heads and bends of the profile. Four layers were opened by boreholes 26 and 27: ballast-crushed stone 1; sand cushion, represented by medium-grained sands of low degree of water saturation, with the inclusion of pebbles up to 15-20%, 2; soils of the embankment core, represented by sandy loam of plastic consistency, 3; soils of the base of the embankment, represented by loams of a refractory texture, 4.

Figure 3 shows the exaggerated longitudinal profile of the path-fragment, which is compiled from the materials of geodetic and geological surveys, is depicted horizontally 1: 10000, vertically 1: 100, geological layers are taken out on the longitudinal profile - item 1 - ballast (crushed stone ), pos.2 - sand cushion, pos.3 - pounds of the embankment core, pos.4 - soil base of the subgrade obtained as a result of processing of radarograms and drilling results, and also show: detailed track plan; line plan of the track being repaired; elevations of the rail head being repaired and adjacent - at double-track sections - tracks, m; elevation, m; the difference in levels of the rail head of adjacent tracks, cm, the design and existing border of the ballast cut relative to the rail head of the adjacent track, cm; design marks of the rail head of the track being repaired, m; slopes% and length, m; crushed stone thickness under a cross tie, cm; change of marks of the rail head under the supports of the contact network, cm in electrified areas; numbers of supports of the contact network and their picking position; suspension height of the contact wire, mm; places for laying geotextiles, geogrids, heat-insulating materials.

Example.

In May 2005, a survey of the subgrade by a set of engineering-geological and geophysical methods was carried out to justify the project of enhanced overhaul of the even route Aleksandrov-Ryazantsevo 115 km pc 0-165 km pc 3 of the Northern Railway. The length of the surveyed area is 50.3 km.

To this end, the survey program provided for the implementation of field engineering and geological drilling with the use of a shock-type manual drilling tool kit and geophysical work using the GPR sounding technique using the Zond-12 E georadar. The survey was carried out in the following sequence: visual inspection; georadar survey; preliminary interpretation of GPR materials; pit drilling and well drilling; analysis of the measured parameters.

A visual inspection revealed the presence of numerous splashes of liquefied ballast in interspersed boxes, in extended excavations and in zero places, almost all existing drainage structures are covered with debris and silted throughout its length, accumulations of surface water due to spring snow melting are noted in almost all low places along the subgrade, the slope of the contact network supports to the field side is also noted in the area of PC 139.4-139.6.

Then, 50.3 km of GPR profiling was performed using a 750 MHz antenna at the ends of the sleepers. Using a 300 MHz antenna, an embankment located in a peat bog was examined (PK 139.0-140.0). During the preliminary processing of GPR materials, a sharp increase in the specific attenuation of electromagnetic waves (a decrease in the amplitude of oscillations) was revealed in the area PK 139.2-139.7 in the depth interval 1.7 m - 4.0 m, which is typical for water-saturated soils.

As a result of drilling at PK 139.5, under a two-meter peat thickness, gray-blue clay of a fluid-plastic consistency of presumably Jurassic age was revealed. At this point for 500 meters (PK 139.2-139.7) the subgrade runs through a peat bog. Drilling wells at the levels of 192.50-192.75 uncovered groundwater, hydrodynamically associated with the adjacent swamp. After comparing all the materials received, a decision was made - during the overhaul of the track on section PC 139.2-139.7, instead of a jointless path, lay the link, track distances were recommended to monitor this section, especially in the spring-autumn period, in addition, to lower the level groundwater at zero places and in excavations, the project provided for the repair and cleaning of existing trays, the restoration of old and cutting new drainage ditches and ditches.

This anomalous zone was contoured, additional boreholes were laid, all the data obtained were taken out to transverse sections and an exaggerated longitudinal path profile, after which a more reliable picture was obtained of the deformation that is occurring at the moment and was occurring earlier in the surveyed area. This made it possible to increase the effectiveness of the survey of the subgrade 3-4 times. At the same time, the cost of repairs will decrease by 10-20%.

Technical and economic result: the inventive method has been used on the Southeastern Railway since 2002, it was first used on the Kolodeznaya-Davydovka section and for examining “diseased” places along the Liskinsky track distance together with the Geological Engineering Base of the Track Service. In 2004, 2005, as well as on the Volga Railway and since 2005 on the Northern Railway.

Using the proposed method improves the efficiency of the survey of the subgrade, reduces the cost of repair work by 10-20%.

Claims (1)

A method for a comprehensive survey of the subgrade of railways, including non-contact georadar inspection, well drilling, registration of defects, analysis of the state according to the measured parameters, transferring the received data to the transverse and longitudinal sections of the subgrade, characterized in that the survey of the subgrade of the railway is carried out sequentially, in a complex with preliminary processing and analysis of the obtained materials to identify abnormal areas and the appointment of control points of drilling and additional georadar profiles, moreover, georadar inspection is carried out with the release of layers with different dielectric constants, and drilling is carried out not only within the identified anomalous zones, but also at each kilometer of the surveyed area, and drilling is carried out along the ballast layer using a manual drilling kit with a description of contamination crushed stone, fraction size and lithology, with a description of the particle size distribution, moisture, density, soil consistency, while the results are obtained s interpret measurements for the purpose of removal of the data on the longitudinal profile exaggerated way.

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