The paper presents the experience of building and structure strengthening in Tyumen soil conditions which are often presented by a soft water saturated clay and sand layer of the quaternary period. All buildings mentioned in the paper had uneven settlements due to complex engineering and geological conditions and the wrong choice of foundation type. Thin drilled injection piles with a diameter of 200 mm were used for foundation strengthening. All the piles were installed on the solid soil base during the drilling process regardless of the depth of its location. No rules have so far been approved to calculate the bearing capacity of thin drilled injection piles. That was the reason for defining the drilled injection pile bearing capacity at every facility. The paper describes the methods and test results obtained in the study. It was found out that all piles had unexpectedly high bearing capacity. The paper also contains the results of geotechnical monitoring before and after base building strengthening by drilled injection piles which show the current decrease of settlements and the efficiency of this base strengthening method.

The paper presents a system for the safe construction assessment of a building and its structures with a developed substructure and with a crucially changed superstructure at the late stage of construction under the conditions of the completed substructure at the early stage of construction. The main specific feature of above-mentioned construction is to ensure the continuity of the superstructure erection in case of the high increased loads on the foundation (mainly on the foundation slab) until it is strengthened. All values of the settlements and deformations of the building were find by using the verified program “STARK ES” and due to the results of the geotechnical monitoring. The paper proposes a verification system for acquired data proceeding to the monitoring and calculated values of settlements and deformations of the foundation slab which ensure the operational safety using the convenient "traffic light" method and the instructions for its successful use.

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