different reasons. Vertical deformation of the steel bottom caused by soil settlements causes additional and often high stresses in the area of direct contact between bottom plate and cylinder sheets. Very unfavorable effects of these settlements occur in tanks where a ring concrete foundation under a cylindrical shell have been used (Type B– Fig. 1 ). Rainwater, which sometimes flows from the tank directly under its steel bottom ( Fig. 3b) , may lead to the loosening of the soil and large deformations of the bottom plate, resulting even in its cracking and tank failure
equivalent stiffness of the stiffest neighboring zone.
In the contrary, for the resistance parameters, we take those of the least-resistant material, possibly reduced in case of smooth interface (case of soil–steel friction, for example).
It is important to note that interfaces are one sided in FLAC-3D; this differs from the formulation of two-sided interfaces in FLAC-2D.
3.3 Initial conditions and material properties
The initial distribution of vertical effective stress and horizontal effective stress are controlled by the given soil unit weight and the
 MACHELSKI C., Modelling of soil-steel bridge structures, (in Polish), DWE, Wrocław, 2008.
 MACHELSKI C., ANTONISZYN G., MICHALSKI B., Live load effects on a soil-steel bridge founded on elastic supports, Studia Geotechnica et Mechanica, 2006, 28, 2-4, 65-82.
 ANTONISZYN G., Is the road pavement structural element of the bridge?, Geoengineering: roads, bridges, tunnels, (in Polish), 2009, 3, 76-79.
 JANUSZ L., MADAJ A., Engineering structures made form corrugated plates
position in the axis of one of the tubes to the axis of the other tube. The time of moving the thermometer measured using appropriately set contacts was ~20 ms.
For the experiment, carbon dioxide and argon were selected (CO 2 as the gas sorbed on coal). These gases have similar molecular weights of 44 and 40, respectively. Argon sorption on hard coal was found to be low compared to the sorption of carbon dioxide. The gas from the bottle flowed through a reducer and a copper coil placed in water, and then, it flowed into the atmosphere through a steel tube. The usage/flow
dilatometer test became the starting point for the considerations in this article, in which, the technique of their execution and methods of interpretation of the obtained results were discussed in detail.
Flat Marchetti dilatometer is a measuring device first presented in 1975 by Prof. Silvano Marchetti from Italy. The device measured horizontal deformation of the ground and was characterized by an uncomplicated structure – it consisted of a sharpened steel plate and a circular membrane placed at the shoulder. In his scientific work published in 1980, Marchetti described