In this article, we examined the Starobinsky gravity model in homogeneous and isotropic space-time described by the Friedman-Robertson-Walker metric. In the framework of this model, cosmological parameters were described that explain it in the early and late evolutionary times, such as the slow roll parameters, perturbation of curvature, scalar-tensor ratio, equation of state parameter and deceleration parameter. For reconstruction, an ansatz of a special type was chosen, which can be considered as a generalization of the Chaplygin type of gas. Energy conditions are also calculated for this model. Dependencies of these parameters on cosmological time are plotted graphically.

Abstract

Excavation of pits, trenches for foundations of civil buildings and industrial structures in saturated clayey soils often leads to soil structural change and great decrease in the soil strength and deformation characteristics. In some cases, an artificial sand base is used as a method for construction on saturated clayey soils. However, technology violations and unsuitable material used during construction can be the reason for excess settlement of the erected facilities. The study includes a real example of an emergency situation at gantry crane railways with three hundred meters in length in the town of Tobolsk. The artificial base was made using local sand with specific properties such as subsidence and frost heaving, which were not taken into account in the design process. The observed excess non-uniform base deformations were up to 240 mm. The base properties of the silty sand were analyzed in a laboratory study. Two tests were carried out to simulate possible impact on the artificial sand base. They showed that the values of the initial compaction factor Kcom of sand base were found in the range of 0.87-0.92. So, the base subsidence was about 12% of the actual base deformation and the total base settlement under the total operation loading made about 19%.