Determination of the initial bearing capacity of two-layer consolidating bases of strip foundations

The use of computational software packages is a promising area in the design of foundations for buildings and structures. Finite element modeling of foundation deformations under the design load allows for consideration of soil mass heterogeneity, specific soil properties, and various loading conditions. Designers also have access to approximate analytical calculation methods, such as the layer-by-layer summation method, included in regulatory documents. The integrated use of numerical and analytical calculation results enables informed decision-making. A completely different situation exists in predicting the bearing capacity of soil foundations. Using modern elastic-plastic soil models within the finite element method, the development of plastic deformation zones in the foundation is determined with increasing load. However, the results of modeling the critical failure zone of the foundation are unstable. Most importantly, there is no criterion for foundation failure based on either the development of the plastic deformation zone or the nature of the load-settlement curve. The limit analysis method yields more reliable results. However, having only recently emerged, it requires extensive verification. Therefore, improving analytical methods for calculating the bearing capacity of foundations remains a pressing issue today. The theoretical basis for determining the failure load is the static method of the theory of limit equilibrium of soils. Currently, proven methods for determining the bearing capacity of homogeneous foundations in a stabilized state and recommendations for accounting for the unstabilized state have found widespread application. The next step is to account for the heterogeneity of the foundation. For the initial case of a two-layer foundation in a stabilized state, a special method for calculating the bearing capacity was recently proposed, based on the integrated use of bulk media statics solutions and the logarithmic spiral method. Further improvement involves accounting for the unstabilized state, i.e., obtaining a solution for a two-layer foundation composed of consolidating soils. Such a solution, which is the subject of this article, can be obtained using the theory of instantaneous strength and a static solution for the bearing capacity of a homogeneous consolidating foundation.

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