During the building reconstruction with floors addition, there is a need to evaluate the building frame and foundation soil bearing capacity, especially if there are deviations from the design parameters. As a result of the field and numerical studies, we determined the basic change patterns in the stress-strain state of the 12-storey building load-bearing structures with a monolithic reinforced concrete frame due to uneven pile foundation deformation. We also found the influence degree of the existing deviations from the design parameters to the structures bearing capacity. The research results can be applied in reconstruction conditions with a significant increase in the load on the existing load-bearing elements of the building and on the pile foundation.

Studies of the piles bearing capacity after strengthening soil by cement mortar pressure injection were carried out to determine pile foundations bearing capacity increasing patterns in a result of soils cementation. Depending from the volume and cement mortar technological injection parameters, the soil stress state around the pile changes, additional pile-soil compression occurs and the friction along the lateral surface increase, as well as the soil resistance under the pile bottom end. Cementation effect on the pile bearing capacity for different injectors location and the number of piles in the foundation were determined by tests. The research results can be used in the pile foundations reinforcement design in conditions of reconstruction with increasing loads on the foundations.