Prediction of principal stresses from external loads in sandy soils and ash-slag mixtures

Introduction. Earlier studies indicate that a change in the structure of any material triggers a change in its stress state development pattern. It is obvious that when the type of soil, humidity and density of the massif change, its mechanical characteristics and the stress state change respectively. Therefore, to study the influence of genesis on the stress state, the authors analyzed dependences, proposed for predicting maximum principal stresses arising in soil massifs subjected to external loading by a round plate. The analysis shows that taking into account the features of the stress state development in the proposed models is connected with mechanical characteristics of soils. However, previous studies show that these dependencies are not universal. Materials and methods. To verify the adequacy of the solutions, experimental studies were conducted to determine pressures arising in sandy soils, ash-slag mixtures subjected to external loading. Physical and mechanical characteristics of the materials in the state under study were determined (such as the angle of internal friction, specific adhesion, modulus of deformation (elasticity)). Results. The experiments show that the pressure attenuation intensity increases with depth along with the increasing density of massifs, regardless of the genesis, and attenuation is more intense in ash-slag mixtures. The authors have found that the development of stresses in soils of various genesis can be described by applying solutions based on the mechanics of the granular medium (Kandaurov’s solution) and continuum mechanics (this solution was proposed by Frohlich). Conclusions. The results of the work demonstrate the need to employ different approaches to predicting the stress state in soils of various genesis. Correlations between mechanical characteristics of soils (such as the friction angle and the modulus of elasticity) and parameters of the distributing medium indicate the need to study clay and other types of man-made soils.