Kravets I. Methods for assessing and improving the load-bearing capacity of a non-uniform roadbed of a railway track

The dissertation is devoted to the decision of an actual problem of development of methods of estimation and increase of bearing capacity of the inhomogeneous earth cloth reinforced by tubular drainage designs, at action of static and dynamic loadings from vehicles. The theoretical side of the task was solved by improving analytical methods for assessing the bearing capacity of a non-uniform roadbed, taking into account a set of factors: physical and mechanical characteristics of subsoil soils and tubular drainage structures and loads from vehicles. Experimental and practical side - is solved by developing an inertial device for determining the bearing capacity of inhomogeneous earth and a way to increase its bearing capacity. The technical condition of the railway track and the problems of ensuring its strength under the action of floodwaters and waterlogging in sections of the track during operation are analyzed. The georadar studies of problem areas of the railway track have been carried out, on the basis of which the distribution of characteristic signs of a non-uniform roadbed in the vertical plane and the boundaries of their location have been found. A mathematical model for estimating the bearing capacity of a non-uniform roadbed reinforced with tubular drainage structures has been developed. The stress-strain state of a non-uniform roadbed is estimated taking into account the physical and mechanical parameters of soils, tubular drainage structures and dynamic loads from the rolling stock of railway transport. A method for calculating the dynamic loads from vehicles with a non-uniform roadbed, which allows to take into account the influence of geometric irregularities on the rail track on the bearing capacity of the subsoil. A method for laboratory determination of the degree of compaction of the subsoil based on inertial measurements of accelerations in the soils of the non-uniform roadbed has been developed. Which allows you to assess the degree of compaction of the ground depending on the speed of propagation of elastic shock waves. Experimental researches of determination of speed of propagation of elastic waves in a homogeneous earth cloth from coarse-grained sand and inhomogeneous earth cloth from coarse-grained sand with layers of clay on height of cross section of an earth cloth are carried out. It is established that the speed of propagation of elastic shock waves in an inhomogeneous ground is lower than the speed of propagation of waves in a uniform roadbed. During the dynamic interpretation, using statistical analysis, the characteristic features of the distribution of accelerations in the body of the embankment of the uniform and non-uniform roadbed depending on the degree of their compaction, which will monitor the condition of the subsoil during operation. Because, it is established that the degree of soil compaction directly affects the deformation characteristics of the ground and the technical condition of roads in general. A method is proposed to increase the bearing capacity of the diseased railway bed by applying a combined arrangement of drainage pipes in vertical and horizontal directions in the construction of the roadway, which is a means of eliminating the factor that causes its deformation and defects, namely water drainage. An assessment and study of the stress-strain state of the subsoil reinforced by the design of tubular drainages by the finite element method. Recommendations for increasing the bearing capacity of a non-uniform roadbed by a combined method of laying a structure of tubular drainage in the body of the embankment of wet soil and a method of early prevention of road deformations by monitoring the developed inertial device. The technical and economic calculation of introduction of the offered method of measurement of degree of density of soils of a ground cloth is carried out.