# Control and Analysis of Layered Soil Structure to Ensure Railway Roadbed Stability
## 1 Introduction  
Ensuring the stability and safety of railway infrastructure is one of the key tasks of the transport industry. The soil condition on which the railway track is located directly affects its reliability and durability. Changes in the layered structure of the soil can lead to serious problems such as track subsidence, differential settlements, and deformations, which can ultimately cause accidents and disruptions in train traffic [1]. Traditional methods of monitoring soil conditions, including electrical resistivity tomography and seismic surveys, are widely used to assess soil properties. However,these methods have several limitations: low resolution in heterogeneous media, high sensitivity to external interference, and the need for complex and time-consuming data processing [2; 3]. These shortcomings make it difficult to promptly detect critical changes in the soil and take prompt measures to prevent accidents. However, despite their effectiveness, traditional geophysical methods have certain limitations. For example, electrical resistivity tomography may struggle with resolution in highly heterogeneous soils, and seismic surveys can be influenced by external noise and require extensive data processing. The accuracy and reliability of these methods can be reduced in challenging geological environments, which underscores the need for advanced approaches that address these shortcomings [3]. Recent advancements in geophysical monitoring have introduced innovative techniques that offer enhanced precision and efficiency [4; 5]. For instance, methods that monitor changes in the phase of electric signals at electrode receiver lines have shown promise in overcoming some of the limitations of traditional methods. These phase-metric techniques leverage the sensitivity of phase changes to variations in soil characteristics [6]. The main information that needs to be obtained is the following: the granulometric characteristics of the soil, porosity, moisture level, degree of plasticity and deformation of layers, and depth of groundwater [7; 8]. While direct geophysical monitoring methods offer detailed insights, their application in railway tracks presents significant technical and economic challenges. Recent advancements in geophysical techniques could potentially address these limitations and improve the feasibility of comprehensive soil monitoring [9]. Previously, the authors of the present work obtained the following original scientific results on the current topic [6]:  
* A methodology for applying phase-metric methods of geodynamic monitoring in various tasks;
* A method for forming an artificial multiphase field of a given structure in a controlled area of the near-surface part of the geological environment, allowing for observation of various geodynamic processes under various measurement conditions;
* Methods for recording phase parameters and characteristics of a multiphase field by a single-point pole receiver and a differential pair, allowing for increased sensitivity of measurements and solving problems of spatial localization of geodynamic processes in a controlled area;
* A method for receiving and primarily converting measured signals recorded by point pole receivers in the field of geodynamic monitoring systems based on phase-metric monitoring methods and devices, allowing for real-time assessment of phase parameters and characteristics of a multiphase field in a controlled area of the geological environment. This study proposes an innovative approach based on the phase-metric method of geoelectric monitoring, which will allow for highly accurate determination of soil characteristics by analyzing phase changes in electrical signals [10; 11; 12].