Pile foundations of buildings on a base with layers of limestone

Positive experience of arranging high-rise buildings with underground parking lots in soil conditions that have a layer of limestone in the zone of their interaction with pile foundations is presented. It was found that the engineering and geological conditions of Odesa should be classified as complex, in particular due to the presence of weak loess soils in the upper part of the section, and limestone layers in its lower part. In the middle part of the section there is a layer consisting of heavy loams and clays. More compressible sandy loams and meiotic clays serve as the base of the limestones. The insignificant thickness of the middle layer makes it necessary to transfer the load from the buildings with piles to the limestone. With their insignificant thickness, the presence of cracks and outcrops, it becomes possible to develop an excessive tilt of the building as a result of uneven (one-sided) pressing of limestone, which has the nature of a cemented rock. It has been proven that to create a reliable pile foundation, it is important not only to hydraulically tamponade the excavations, but also to consolidate the massif in the area of ​​their location by high-pressure injection of soil-cement solution using cuff columns, as well as to correctly assess the mechanical characteristics of limestone and, first of all, its strength parameters. The conditions for the construction of buildings with a high number of floors on prismatic piles are substantiated. The results of monitoring their subsidence during construction and operation are presented. The experience of 3D modeling by the method of finite elements (FEM) of joint work of the pile-slab foundation of buildings with a base containing layers of limestone and layers of more compressible clay soils in the zone of underground workings is presented.