The dynamics of changes in the physical and mechanical characteristics of the base soil

This article discusses the change in the physical and mechanical characteristics of the foundation soil during the operation of construction projects and the possibility of taking these changes into account when designing shallow foundations. Methods Based on the assumption that the weight of the engineering and geological elements of the base remains constant regardless of the level of existing additional vertical stresses, an expression is obtained for determining the coefficient k_γ, taking into account changes in the density and specific gravity of the soil during the operation of buildings and structures. Moreover, based on the assumption that the plot of the additional vertical stresses is triangular, an equation for calculating the coefficient k_c is determined, which allows determining the change in soil adhesion during the operation of construction projects. Using the coefficients k_γ and k_c, an expression is obtained to determine the change in the calculated resistance of the soil of the base during the operation of construction projects. Taking into account the coefficient k_γ with the width of the projected foundation more than two meters with a ratio of settlement of the base to the depth of the compressible thickness equal to 0.3 leads to an increase in the design resistance of the operated base by 5%; by 3% and 1% with S/H_c = 0.2 and with S/H_c=0.1, respectively. In this case, depending on the width of the designed foundation, taking into account the coefficient k_c allows you to exceed R by 25%. Joint accounting of the considered coefficients leads to an increase in the calculated resistance of the soil of the base by an average of 27%. Conclusion The obtained coefficients, taking into account changes in the specific gravity and soil adhesion during the operation of the base, make it easy to estimate the growth of the design resistance during the compression process, which in turn makes it possible to save an average of 10% of the material when designing shallow foundations.