No abstract

In modern urban planning, in most cases, the construction of buildings and underground structures has a negative impact of new construction on existing buildings. As a rule, the foundations of new buildings are designed with a greater depth of laying compared to existing buildings. As a result of excavation work and subsequent installation of load-bearing structures of underground structures, existing buildings are subjected to uneven subsidence. Cracks may appear in the walls and the serviceability of structural elements may be impaired. Before the geotechnics there is a task to determine the dimensions of the zone of influence of new construction, ie the area where negative processes of stress-strain formation can occur. To comply with the safe operation of existing buildings, there is a need for a reliable forecast of additional deformations of existing buildings and structures, as well as the choice of a rational solution for the protection of the pit. Modeling of the stress-strain state of the retaining wall of the pit with different diameters and changes in the number of rows of piles. Calculations of the stress-strain state of the protective structures together with the soil base were performed using the finite element method for a horizontal load of 1 m.p. retaining wall (the problem of flat deformation). 4 variants of the problem were solved: V1 - retaining wall with piles 13.5 m, 420 mm in diameter, arranged in one row; V2 - retaining wall with piles 13.5 m, 620 mm in diameter, arranged in one row; V3 - retaining wall with piles 13.5 m, 420 mm in diameter, arranged in two rows; V4 - retaining wall with piles 13.5 m, 620 mm in diameter, arranged in two rows; The influence of increasing the diameter of piles in the structure of the retaining wall on the increase of the moment of inertia of the section, which leads to the perception of a greater value of bending moments, is shown. The technical and economic comparison of the pit fencing options is performed. The most rational solution of excavation of the pit in these conditions is revealed.

The results of work research of engineering protective structures in a densely built–up area with difficult engineering–geological conditions have been presented. The modeling of the geotechnical problem of deep excavation protection using a three-tier retaining wall has been performed.  The task of mutual influence of existing building and deep excavation with the change of distance between them is solved. The grafs of displacement’s dependence several tiers of retaining walls from the distance to an existing building have been presented. According to these data, a plot of the dependence of displacements of separate tiers of retaining walls from the distance to an existing building is constructed. The problem is solved by the finite element method using a nonlinear model of a solid soil environment. The character of the formation of zones of potential slip surface slope is revealed. The dependence of bending moments of the retaining walls from the distance to the existing building is shown. A safe location of an existing building to a deep excavation has been substinated.