Verification of the results of physical and numerical modelling of the “pile – rock mass” system

Introduction. The construction of objects of a high class of responsibility, in particular, requires the transfer of high loads to the foundation, which is often achieved through pile foundations buried in rock masses. The calculation of their bearing capacity includes predicting the proportion of the load taken by the side surface of the pile and its base, however, the sum of these values is unacceptable, for this reason it is necessary to accurately predict the proportions of these values. This forecast is complicated by the variety of properties of rocky soils, the scale factor and the complex work of the “pile – rock mass” contact. There are several methods for predicting pile performance, in particular the finite element method. The purpose of this work is to verify the results of physical and numerical modelling implemented in the ZSoil software package (PC),
for the subsequent deeper study of the joint work of the pile and the rock mass.

Materials and methods. Numerical modelling was carried out in the ZSoil 3D software-computing complex, taking into account the actually obtained characteristics of the materials used. To carry out physical modelling, three specimens were prepared, identical to the numerical model, and then tested in a triaxial compression installation.

Results. Qualitative and quantitative results of the simulation were obtained. Qualitative results — the destruction of the entire “pile – rock mass” contact was established both on laboratory specimens and in a numerical model. Quantitatively, the results were compared using graphs of the dependence of the settlement of the pile head on the stresses that arise.

Conclusions. Both according to the results of numerical and physical modelling, the nature and stages of destruction of the system are identical to what was established during the visual inspection of the specimens and the results obtained in the PC. A quantitative assessment of the results was carried out by comparing the obtained graphs of the dependence of the settlement of the pile head on the stresses arising in it. The comparison showed a discrepancy in values at the characteristic point corresponding to the complete destruction of the contact, ~ 15 %, which confirms the applicability of the PC in the subsequent study of the system.

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