Specific features of interaction of massive slab foundations with the soil

At this time, the actual direction of research in the geotechnical sciences is the rehabilitation and design of energy objects, which in Ukraine were often built on slab foundations (NPPs, TPPs and others) The arrangement of slab foundations, which are large in plan, which determines the peculiarities of their interaction with the base. A large quantity of experimental work was carried out at such objects, and this publication is based on these results. In order to preserve the experimental data and identify new factors of interaction between slabs and the base, namely the rise of the bottom of the pit, when driving piles at the construction site, the compressible zone was identified with the help of depth marks, which differs significantly from the real one (12 m practically against 28 m calculated by the DBN coefficients). The dilatancy processes that caused the rise of individual piles up to 30 cm were studied separately, which required clarification of the circumstances under the sole of driven piles and the role it takes in the formation of slab foundation settlement. The analysis of the stress-strain state of structural elements of each building (structure) always requires identifying the real active deformation zone. The publication presents the materials of the analysis of the stress-strain state of the base depending on the size of slab foundations and the rate of payload application (for example, silo buildings). A comparison of the depth of the compressible zone under the slab using the method of layer-by-layer summation (coefficient from DBN) and the actual Hst, which was determined by depth marks installed to a depth of 28 m, was carried out. After the design load was applied, the depth marks did not respond at a depth of more than 12 m. The difference in the interaction of large-sized slabs with the foundation is shown, and the option of short piles, which improve the properties of the foundation but do not perform the function of stress transfer to deeper soil layers, is considered. An example of pit lifting for NPP foundation slabs (70x70 m in size) with the option of driven piles 14.0 m long with a cross section of 35x35 cm is presented. During the works, the bottom of the pit rose by more than 50 cm, and the piles exceeded the rise by 30 cm. This fact led to additional experimental work to find out whether there was a void under the sole In order to popularize the experimental data and preserve the experience of designing critical facilities on large slab foundations, this publication was prepared.