On the question of engineering and geological zoning of territories within local tectonic structures

Abstract

The relevance of the research lies in the approach to assessing the engineering-geological conditions within the local tectonic structures and their role in the formation of the properties of rocks and the state of the massifs composed by them. The formulation of the question regarding the rocks of the red-colored terrigenous formation as a separate object of engineering and geological research allows us to take into account the features of the history and mechanism of development of local structures, as well as their influence on the reaction of rocks in this case. Particular attention is paid to the role of tectonic fracturing as a consequence of the mechanism of development of local structures and its influence on the activation of hypergenesis processes. An analysis of the behavior of rocks during the development of local structures and the response of the massif to changes in the state of rocks and the activation of hypergenesis processes was carried out, which, in turn, determined the engineering-geological situation at the current moment. Particular attention was paid to the assessment of tectonic fracturing, identification of weakened zones and criteria confirming the correctness of their identification. The methods used in solving the tasks were reduced to a comprehensive study of local structures: the study of the history of their development, size, amplitude of uplift of the foundation, instrumental survey of fracturing in outcrops with subsequent construction of a map of fracturing, sampling, laboratory studies of the structure and properties of rocks, fixation of exogenous processes within the structure. The results of the research were the established dependences of the influence of tectonic fracturing on the state of rocks at three levels: the microlevel (the reaction of the minerals of the constituent rocks at the level of the crystal lattice in the form of defects that have arisen); mesolevel (changes in the physical and mechanical properties of rocks); macrolevel (activation of exogenous processes). Thus, criteria have been defined that allow using them to confirm the correctness of the selection of the most fractured sections of the massif. The correctness of the methodology for identifying zones of increased fracturing within local structures is confirmed by the criteria that were used to solve this problem. It can be used as a basis for large-scale geotechnical zoning within local tectonic structures.