Study of the stress-deformation state of the soil base and foundations for equipment under significant horizontal loads

Abstract

The study of the possibility of calculating foundations for stability against displacement along the sole and overturning under significant horizontal loads was carried out by the LIRA-SAPR computer software complex.
 The study was carried out by analyzing the amount of horizontal (sliding) and vertical (overturning) displacement of the foundation under the shunting winch under two variants of the engineering and geological conditions of the construction site.
 Through "manual" calculation, it was found that the stability of the foundation is ensured in the first variant of geological conditions, but not in the second one. Therefore, such geological conditions are illustrative for the study of calculation possibilities using the software complex.
 The foundation with width b=1.8 m, length l=4.2 m and height h=2.35 m is modeled by volume finite elements. The bottom layer, which is in contact with the soil base, is modeled by quadrilateral finite elements of the slab (slab on an elastic base).
 Friction under the footing is modeled by finite stiffness links (single-node finite elements) that are added at each node of the slab that models the bottom layer of the foundation.
 The stiffness of such finite elements in the direction of the global axis X and axis Y is determined automatically in the "GRUNT" system according to the methodology of SNiP 2.02.05-87.
 Summarizing the conducted research, we can say that the advanced capabilities of the LIRA-SAPR PC, in particular, the implementation of the algorithm for determining the stiffness coefficients of the base according to the SNiP 2.02.05-87 method, allow calculating foundations for resistance against displacement along the sole and overturning by numerical methods. This allows, firstly, to completely automate the calculation of the foundations, and secondly, during the automated calculation, the negative influence of the neighboring foundations is additionally taken into account, which is relevant, since the foundations for machines and mechanisms are mainly subjected to significant horizontal loads.
 In addition, the conducted research revealed the absence of a kinematic criterion for assessing the stability of the foundation. In manual calculation, the criterion for ensuring the stability of the foundation against displacement is the condition of static equilibrium. When calculating by the method of finite elements, implemented in PC "LIRA" and similar, displacements are decisive, so it is considered promising to study the issue of the criterion of stability of the foundation by displacements.