The present paper describes first experience with the described X-ray CT-FEM analysis. It focuses on geocomposites arising by chemical grouting of coal substances and use mathematical modelling of response to a load. The application potential of this new methodology is found in utilization of the obtained (homogenized) properties for solving the stability problems by numerical modelling of geotechnical projects. The contribution will touch the following interacting research activities: i) Application of X-ray computed tomography (CT) for visualization of structure of geo-materials, mainly geocomposites consisting of rocks (coal substance) and chemical grout materials (polyurethane resin), ii) analysis of a need for modification of the digitalized data and finding correspondence between CT values and local material properties, iii) numerical testing of digitalized samples for obtaining homogenized properties and clearing up sensitivity to changes in local material properties and sensitivity to geometrical data, iv) experimental validation by means of laboratory tests of calculated homogenized properties.
In a number of human activities related to underground construction and mining of raw materials, we meet geotechnical problems, which are connected with the rock mass quality. Rock mass properties and quality represent the basic factors influencing in a crucial way the solution of geotechnical projects. The modern geotechnical approach considers the rock massif into account as one of the constructional elements. Unsatisfactory rock mass properties are often a reason, which does not allow to simply implement geotechnical projects and which requires to suggest and realize a number of special geotechnical interventions as well as to use specific instruments and methods to influence (improve) rock mass properties. One of possibilities for such geotechnical interventions to rock mass is pressure grouting with the aid of chemical grouting media. These grouts can be successfully applied to influence mechanical and other physical rock mass properties. At the present stage of development of chemical grouts, based mainly on polymers, the grouting process produces new composite geomaterials (shortly geocomposites) with properties, which are significantly different from the properties of the original rocks. These geocomposites can be defined as geo-materials that are produced in the process of pressure grouting on the basis of rocks as a matrix and chemical grouts that fill in the voids in the rock mass as a binding agent. The required properties of geocomposites are important factor influencing the choice of the grouting medium and also the effectiveness of the grouting technology. In the recent years, more and more advanced methods and procedures are applied to investigation of properties of geomaterials and geocomposites. They make possible to study the behaviour of geomaterials occurring in various conditions in more detail. For example, we can mention the visualization methods, which exploit digital processing of images, mostly acquired with help of digital cameras or microscopes. From the digital image analysis diverse material characteristics can be derived, e.g. the structure and texture of materials, shape and size of grains and pores, amount of pore space and extent of pore saturation by grout material, damage level, etc.