Single Foundations of Framed Buildings and Skeleton Structures in a Compacted Base and Their Horizontal Load Resistance

In practice of construction in Russia in case of plastic soils bedding, the cast-in-place foundations are used, constructed in a compacted base in kind of tamping in the soil of the 2-4 m depth pyramidal holes with the subsequent ballast tamping into the hole bottom and placing concrete in the said hole. Such foundations are advisable under the columns of framed buildings and structures. They are significantly more effective comparing to the pile foundations with a cast-in-place raft, as without a raft the volume of excavation works and formwork decreases significantly. While design of such foundations for the framed buildings and structures, the horizontal load and bending moment calculation is of great importance. According to the above calculation, the horizontal displacements of a foundation and its reinforcing are evaluated. The aim of the given paper is to solve this problem. The complex of the experimental – theoretical investigations has been carried out by a special program and included the horizontal load static tests of the foundations in tamped holes with the parallel CPT. By results of site experiments the rules of deformation of the stressed-deformed state are obtained and the criteria of achieving the limit state of a system “foundation-soil” are revealed. In particular, it was stated that the tamped in ballast creates a zone of an increased strength in a foundation base that prevents its horizontal displacement due to the horizontal load. Based on experimental data, a design scheme was constructed and a method of such foundations horizontal load calculation was worked out including CPT