Ways to Improve Hydrological Efficiency of Railway Subgrade Drainage

Abstract

Purpose: Hydrological rationale for drainage system buildings that effectively drain poorly permeable subgrade soils. As a result of watering of soils by rainfalls and groundwaters, track upper structure undergoes deformation and loses its strength. To exclude adverse processes, various drainage devices and drainage systems are used. In the modern world, traffic speed and freight transportation quantity have risen and the load on track superstructure has significantly increased. To reduce risk for drainage system buildings it is necessary to apply hydrological requirements to ensure moisturizing regime of subgrade soils. Methods: For new structures, traditional water-balance method for drainage efficiency assessment is used. The method takes into account two main types of moisturizing: atmospheric and mixed ones. For atmospheric watering, we used the data on water estimated inflow to a drainage in Russia North-West zone. Atmospheric nutrition may be absent in the case of geomembrane usage on subgrade major platform. The distance between collectors is determined by the author’s methodology obtained by an analytical method. Results: The new structure of gravel drain is proposed. It has been proven that the proposed structure in poorly permeable soils drains a subgrade more efficiently than a subditch drainage does. An example of a hydraulic calculation of such a drain is given, the distance between outlet collectors in the set conditions is determined. Practical significance: Due to the use of gravel drainage, subgrade soil moisture will decrease that will lead to the subgrade bearing capacity increase. The results can be used in poorly permeable soils which prevalence is quite high. Structures, including gravel drainage, can be applied in combination with traditional ones.