The main factors affecting the convergence of calculated and actual values of deformations of existing buildings

Abstract

A study of the interaction between an underground structure and the soil mass in which it is located is based on mathematical modelling by means of geotechnical software packages. Possible settlement of the foundations that support the foundations of buildings located within the influence area of underground construction is normally calculated with the PLAXIS software package. The actual settlements of these buildings when compared to the simulation results show differences in a wide range from 3 to 75%. Specific values are predetermined by the method of excavation support and the adopted technology of works. The paper analyses the ratio of actual and calculated (by different models, including the Coulomb-Mohr model and various modifications of the Hardening Soil Model as the most frequently used in our country and, therefore, analysed most thoroughly in respect of their advantages and drawbacks) deformations of existing buildings during underground works carried out in the vicinity. Factors influencing the deformations are considered. Numerical discrepancies for different methods and in different soils (sand, loam, clay) are given. Possible reasons for discrepancies are formulated. The deviations are strongly influenced by the adopted calculation scheme. A corresponding study on a detailed level required mathematical modelling, which was carried out using the example of excavation of a construction pit for the entrance hall of the Butyrskaya underground metro station in Moscow and a nearby building.