Micromechanics of geomaterials
To improve the strength of rock structures, we can use grout made from various substances, including polyurethane resins.
The properties of a composite material (geocomposite) can be studied by creating a mathematical model of a representative volume and applying various types of loads to it. Thus, we can also look for the most suitable resin composition, determine its sensitivity to changes in composition, assess grouting technologies, etc. The use of mathematical modelling and high-performance parallel computing techniques together with computer tomography, allows for the analysis of mechanical properties and the optimization of materials with complex internal structure.
Solving problems of multiphysics (fluid flow and mechanics)
This discipline mainly focuses on flow in porous media in relation to mechanical deformation. This problem is prevalent in geomechanics in the use of underground oil and gas fields, as well as in the underground storage of carbon dioxide. Another area includes the sealing of underground spaces that are necessary, for example, for the underground storage of spent nuclear fuel. In this respect, the Research Program team at the Institute of Geonics is taking part in the international Decovalex project (short for “Development of Coupled Models and their Validation against Experiments”) and in the modelling of SEALEX experiments (the long-term monitoring of the sealing ability of swelling bentonite) in the experimental minitunnel (60 cm in diameter) in the Tournemire underground laboratory in southern France – see the figure. In this experiment, the modelling involves unsaturated flow in bentonite as well as the surrounding rocks and the mechanical response involving plasticity, swelling, changes in the pore space and other relatively complex and non-linear effects.
Tuning of shock absorbers and mapping their movements
In mechanical systems, we encounter vibrations that are transmitted from the surroundings to the given piece of equipment. Such vibrations are generally undesirable and may even cause damage to a mechanism; they must therefore be dampened. One way of doing so is to install a shock body that absorbs energy and thus dampens the vibration of the entire system. Although this idea is simple, it turns out that finding the correct damper setting is a difficult engineering problem. The model is extremely sensitive to initial conditions, particularly to resonance frequency. Therefore, simulations give us a powerful tool to locate bifurcation boundaries for which the total vibration is minimal, and allow us to study trajectories that can be periodic, quasi-periodic or even chaotic. Using appropriate simulations, we are able to find the perfect damper setting and determine the mass of shock bodies, spring stiffness or gap width of the dampener’s clearance.