Possibilities of seismic methods for the estimation of a railway roadbed state under the conditions of the far north
The article presents results of monitoring state of railway subgrade using seismic methods in the Far North area. Purpose: The purpose of the studies is to find out reasons of subgrade subsidence in turfed soils of Onezhsky District of Arkhangelsk Oblast. Methodology: Studying soils in foundations of subgrade, a complex of active and passive methods was used, including: seismic exploration of refracted waves, multi-channel analysis of ground waves, and engineering seismic analysis based upon spectrum analysis of seismic noises. This complex enabled considering and estimating the system “subgrade-soils of foundations”. Results: A relative high capacity of weak soils, probably containing turf, lying under subgrade. Sections of increased water saturation in subgrade soils were found out. Loads from passing trains and resonant effect in weak soils cause its compression resulting in emergence of subsidence. Resonant effects whereby are not that strong, whereas passing trains have a more significant impact on the state of subgrades. Practical significance: Elaboration of technology of quick estimation of state of railway subgrade for immediate detection of a dangerous defect at an early stage of its development is a topical and acute challenge.