Masyw skalny jako podłoże budowli

The verification of limit states conditions of soil and foundation for an object constructed on bedrock requires a quantitative determination of the construction zone of influence. Due to time and cost factors, it is usually limited to boreholes performed in order to indicate the soil type and profile in terms of crackings. To determine the internal forces of the footing and construction for larger objects, especially statically indeterminate structures, it is crucial to know, e.g., the values of deformation and elasticity moduli. This paper presents the results of a number of tests performed to determine the stiffness of bedrock under silos in reconstruction. Trial loadings were performed and the settlement of soil under the adjacent construction was observed. Soil behaviour under the reconstructed silos was also monitored. Some of the results of the above-mentioned investigations served as the basis for back analyses carried out using the finite element method (FEM), in which stiffness parameters of rocky soil were determined. Based on the investigations and analyses, it was found out that the initial and secondary deformation moduli do not exceed the value of 230 MPa, which is at least a few times less than the elasticity moduli (455-1244 MPa). The analysis of internal forces in silos foundations, performed by the designer in order to indicate the stiffness of bedrock, resulted in the replacement of other 10 walls of the silos, without the necessity to modify the foundations.