Application of the boundary element meth-od to the mechanics of deformed soils

Abstract

Due to the transition of modern buildings to the frame-monolithic scheme, buildings grow up and down. This increases the pressure on the foundations and leads to the need to solve nonlinear problems of soil mechanics in their design, since the main problem of technical systems is reliability. Recently, there has been a clear tendency to strengthen theoretical research in foundation engineering. Obtaining reliable modeling results in most cases is reduced to the use of nonlinear elastic-plastic models based on the theory of plastic flow, dilatancy relations of V.M. Nikolayevsky and I.P. Boyko.

Domestic geotechnics is on the path of intensive development. Numerical methods based on elastic-plastic models are widely used. The destruction of discrete materials (including soil) occurs as a result of the accumulation of plastic (residual) deformations, which in the limiting state causes a break in the continuity of the massif in the form of mutual slippage of its particles. The effect of plasticity is manifested in the development of displacements and redistribution of internal forces. The strength of the bonds in dispersed soils is much lower than the strength of the particles themselves, and in the absence of adhesion forces (sand), the main factor of deformation of the soil base is the forces of contact interaction and deformation associated with repacking of particles.

The main direction of development in construction is the use of new, rational and efficient pile designs that would increase their bearing capacity, manufacturability and installation.

Low utilization of the material strength of square piles - low specific bearing capacity (25-60%) - hinders technical and economic progress in construction and requires the use of new efficient and rational pile designs. The introduction of piles with a complex cross-sectional shape is promising in this direction and is described in (Malyshev, 2011).

Despite a considerable number of experimental studies of piles with complex cross-sectional shapes, there are few specific guidelines for their operation and calculation. The most efficient piles are cross-sectional, I-beam, and tavern piles. The least effective are round and square piles. It is also important to take into account and not to take into account the filling of the volume between the pile ribs with soil, since piles with a complex shape of the lateral surface (I-beam, I-beam, cross-shaped) have a different nature of soil compaction around their lateral surface and involve in their work some compacted soil zone that is formed between the pile ribs during their deepening, as noted in (Malyshev, 2011).

Therefore, verification of the methodology for calculating the bearing capacity and deformation of the soil base by the numerical FEM of this type of piles, static vertical load, is an urgent task.