Prediction of principal stresses due to external load in sans mass considering its mechanical characteristics

Introduction. A part of the methods for designing earthworks and foundations is based on solutions for predicting the stress state of soils under the action of an external load, which do not take into account the structural features of the material. This is in conflict with current studies, which indicate that changes in the moisture content, density, and shape of material particles entail changes in the mechanism of stress state formation. According to some research, when the type of soil, moisture content and density of the mass change, both its mechanical characteristics and the stress state change, which requires consideration in the design of earthworks and building foundations.The method of research. To study the stress state arising in sandy soil with different mechanical characteristics, experimental studies were carried out to determine the pressures in sand of different density and moisture under the action of an external load from a round stamp with an area of 500 cm2. To do this, at a depth of 5, 15, 25, 40 cm along the axis of a round stamp in an array of sand of medium size, mesdoses were set, after which the pressures were measured when the load was applied. For each value of density and moisture created during the experiment, the mechanical characteristics of the sandy soil were determined.Results. The analysis of the existing dependencies for predicting the maximum principal stresses showed that the Kandaurov and Frohlich’s solutions are the only ones that give a connection between the formation of the stress state and mechanical characteristics and allow predicting the minimum principal stresses. The influence of the mechanical characteristics of sandy soil (the angle of internal friction and the modulus of elasticity at different density and humidity) on the Frohlich’s parameter and the distribution capacity coefficient of the medium of the Kandaurov’s solution was established.Conclusion. The analysis of the results of experimental studies made it possible to derive dependencies for predicting the maximum principal stresses of sandy soil at points located at different depths along the axis of a loaded round stamp. The proposed dependencies are a modification of Kandaurov and Frohlich’s solutions, which take into account the relationship between the mechanical characteristics of sandy soil and the parameters of the distribution capacity of the medium.