Comparative analysis of methods of calculation of foundations on subsidence soils

Introduction. Design of pile foundations on subsidence (loess) soils is one of the most urgent tasks in geotechnics. The widespread use of such soils and their high sensitivity to moistening create risks of significant settlements and deformations of buildings. In this regard, it is important to use modern calculation methods and models that allow more accurate prediction of the behaviour of foundations under different operating conditions.

Materials and methods. Two approaches were used to analyze the bearing capacity of pile foundations: calculations according to the normative documentation and numerical modelling in the PLAXIS 2D software package. Hardening Soil was chosen as the design soil model, which takes into account elastic and plastic properties, as well as the influence of soaking and compaction. The bored piles with a widened heel were modelled, which allows for a more realistic assessment of the interaction between the piles and the soil.

Results. Numerical calculations showed that when soils are soaked, the maximum settlement increases from 6.38 to 14.58 cm, and when taking into account the soil’s own weight — up to 15.21 cm, which is close to the maximum permissible values according to SP22.13330.2016. The use of widened piles made it possible to achieve a more uniform distribution of loads and reduce deformations. In addition, methods for reducing subsidence are considered, including preliminary soaking, soil strengthening and drainage measures.

Conclusions. The simulation results confirmed the effectiveness of the Hardening Soil model for analyzing settlements on subsidence soils. The use of bored piles with a widened heel and engineering measures to strengthen the foundation helps to reduce settlements to standard values, ensuring the reliability and durability of structures. The work emphasizes the importance of an integrated approach to the design of foundations on complex soils.

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