ЗНАХОДЖЕННЯ ВЕРТИКАЛЬНОЇ НЕРІВНОСТІ ЗАЛІЗНИЧНОЇ КОЛІЇ ПО ДАНИХ ВАГОНА-КОЛІЄВИМІРЮВАЧА

Two methods are proposed for the vertical roughness determination of railway track depending on data of the measuring carriage – trigonometric series method and numerical method. The vertical roughness and a warp were calculated on each rail. The warp was compared with the measured warp to estimate the precision of the measurement.В статье предлагаются два способа нахождения вертикальной неровности пути в зависимости от измерений вагона-путеизмерителя –на основе тригонометрических рядов и численный способ. Для оценки точности измерений были определены вертикальные неровности по обеим рельсовым нитям и перекос, который был сравнен с измеренным перекосом. У статті пропонуються два способи знаходження вертикальної нерівності колії в залежності від вимірів вагона–колієвимірника –на основі тригонометричних рядів і чисельний спосіб. Для оцінки точності вимірювань було визначено вертикальні нерівності по обох рейкових нитках і перекос, який було порівняно з виміряним перекосом

The complex phenomenological model for prediction of inhomogeneous deformations of railway ballast layer after tamping works

The given article considers the method of calculating the track geometry deformation with respect to uneven accumulation of residual deformations along the track. The technique proposes two significant changes in existing approaches to calculating the efficiency of the ballast layer. The transition from the approach of allowable stresses design in the ballast layer to the deformative approach of accumulations of track geometry deformations allows us to draw conclusions regarding the intervals of track tamping and the duration of ballast layer life cycle. The transition from the determinative to probabilistic approaches makes it possible to draw conclusions not only from the average unevenness, but also with regard to all possible facts of unevenness. The method is based on the mechanism of sudden and gradual deformations occurrence, which depends on a number of key factors: dynamic stresses on the ballast, non-uniformity of track elasticity, performance of current maintenance work. Based on the experimental studies results, the dependencies of sudden deformations and the intensity of gradual deformations on the level of stress on the ballast layer were established. The experimental results of the influence of the subballast base elasticity on the intensity of accumulation of residual deformations are shown. On the basis of the developed method, the prediction of track geometry deterioration for a given structure of the track, the rolling stock and the permissible level of geometric deviations for track maintenance is presented

A laboratory study of pressure distribution and residual settlements in wide grading double layer railway ballast under long-term cyclic loading

Ballast layer has weighty share in the lifecycle costs of railway track. The strict standards and maintenance rules of ballast grading significantly contribute to the ballast costs. One ways to the costs reduction is differential demands to ballast grading for the secondary and low loaded railway lines. Additional one is the different ballast grading over the ballast height. This study presents a full scale laboratory investigation of technical efficiency of such railway ballast under the long-term cyclic loading in comparison with the standard ballast layer. The double layer is presented with standard grading ballast upper layer and bottom sub ballast layer consists of ballast mixture. Pressure distribution under the ballast layer and permanent settlements of the layers are measured during the loading cycles. The reference measurements with standard grading ballast material are carried out. The study shows that initial settlement accumulation of the double layer railway ballast are lower to that of the standard ballast layer. However, the settlements accumulation intensity of the ballast is higher. The analysis of the pressure distribution measurements under the ballast layer and the settlements inside the ballast layer explain the causes of the different settlement accumulation

Studying the Railroad Track Geometry Deterioration as a Result of an Uneven Subsidence of the Ballast Layer

A method for calculating impairment of the track geometry under influence of dynamic loads in the course of passing the track unevenness by the rolling stock was developed. The method takes into consideration interrelated short-term processes of dynamic interaction and long-term processes of subsidence of the ballast layer in a mutual influence on each other. Mathematical model of dynamic interaction of the track in the form of a planar three-layer continual beam system with a two-mass discrete system corresponding to the rolling stock is the basis of the first part of the method. This model makes it possible to simulate dynamic loads from individual sleepers to the ballast when the rolling stock passes geometric unevennesses and the track elasticity unevennesses.The second part of the method is based on the phenomenological mathematical model of accumulation of residual deformations formed using the results of laboratory studies of subsidence of individual sleepers in the ballast layer. Peculiarity of this model consists in taking into consideration not only uniform accumulation of residual subsidence from the passed tonnage but also presence of a plastic component of subsidence which depends on the maximum stresses in the history of ballast loading by each sleeper.A new theoretical mechanism of development of the track unevenness was proposed. It takes into consideration not only residual subsidences of the ballast layer but also appearance of gaps under sleepers resulting in a local change of the track elasticity. This mechanism enables taking into consideration the ambiguous influence of subsidences with occurrence of gaps under the sleepers. Subsidence causes an increase in dynamic loads on the track and the ballast layer on the one hand and onset of the gap causes a decrease in the track rigidity and corresponding reduction of dynamic loads on the other hand.Practical application of the developed method was demonstrated on an example of quantitative estimation of long-term uneven subsidences of the ballast layer when changing the sleeper diagra

Development of a Promising System for Diagnosing the Frogs of Railroad Switches Using the Transverse Profile Measurement Method

We have developed a system for diagnosing the frogs of railroad switches, based on the application of modern microcontrollers of the type ESP with high technical characteristics and the simultaneous use of the information technology IoT (Internet of Things). The proposed system has advantages over mechanical systems in terms of the accuracy of data, their operational processing and submission to user in order to analyze technical condition of frogs at railroad switches. The results of measuring the transverse profile of frogs at railroad switches make it possible to take scientifically-substantiated decisions regarding the need for recovery repair of frogs by the method of surfacing and for control over gradual decrease in their carrying capacity, for establishing their actual technical condition and residual resource.We carried out experimental-theoretical research into longitudinal profile of frogs at railroad switches laid on the reinforced concrete bars. It was established as a result that after passing 50–65 million tons of cargo (that corresponds to the medium degree of wear) the trajectory takes the shape of a bump. We observe sharp hollows on the reinforced concrete base in the zone where a wheel rolls from a rail wing onto the core, characterized by significant total inclination. Subsequently, when the passed cargo increases, the number of sinusoidal irregularities grows. At wear close to maximal (80–95 million tons passed), the percentage of unfavorable trajectories (sinusoidal and hollows) grows; at low wear, they make up 49.8 %, at a wear of 5–6 mm and larger – 88.3 %. Sometimes there is a transformation of the sinusoidal irregularities into the wave-shaped ones.We have established characteristic motion trajectories of the center of mass of the wheel over the frog depending on the wear of rail wings and the core of a frog and the passed cargo. A mathematical model was constructed for predicting the wear of frog profile depending on the total weight of passed cargo

Theoretical Study Into Efficiency of the Improved Longitudinal Profile of Frogs at Railroad Switches

We have developed a comprehensive method to prolong the time of operation of frogs at railroad switches, based on the consideration of a longitudinal profile of the frog, the magnitude of dynamic forces and normal stresses.We have improved a longitudinal profile of the frog, brand 1/11, project 1740, by the method of surfacing under field operation conditions. The slopes of a trajectory after the passage of an average statistical wheel over the proposed profile amount to 3.7 ‰ instead of 10 ‰ for a standard profile of the frog.It was established that increasing a load on the frog to 60 % at the expense of a deflection under the frog beam leads to the accelerated disarrangement of the frog, as a result of fatigue defects at the rolling surface, while the cost of frog operation in this case increases by five times.We modeled a dynamic interaction between the rolling stock and a standard, as well as the proposed, longitudinal profiles of frogs. Calculation of dynamic processes of the nonlinear interaction between the rolling stock and a standard profile of the frog and the profile restored by surfacing, showed that the magnitude of forces for the proposed frog at the motion speed of 150 km/h is 50 % lower compared with a standard longitudinal profile. At linear simulation of dynamic additions of forces, the magnitude of forces decreases for the proposed profile to 30 %.We employed a graphical method to calculate the magnitudes of axial inertia moments and the moments of resistance in the characteristic cross sections of the frog. The estimation of the stressed-strained state of the frog was performed using equations of five moments for a continuous beam on elastic point supports. It was established that stresses at the static calculation of the frog are low and are much less than the maximum permissible magnitude of stresses for a given grade of steel. Therefore, we can argue that the frog works under a load at the expense of existing reserve of strength