Аннотация:The paper presents an analytical study of the main patterns characterizing the spatial orientations of natural shear fractures being critically stressed under the given stress state. An explicit analytical solution to the problem of obtaining all possible spatial orientations of critically stressed fractures for a given arbitrary stress tensor is proposed. This solution is used to analyze the variations of critically stressed fractures’ spatial orientations under gradually changing principal stresses’ magnitudes and directions. Several cases are considered in terms of zones for critically stressed fractures’ poles and stereonet: gradual transition from Normal Fault stress regime to Strike-Slip stress regime; transition from Strike-Slip to Reverse Fault; gradual changes of principal stresses’ directions with constant principal stresses’ magnitudes. Critically stressed fractures are shown to be an indirect indicator of the current stress state of the naturally fractured rock mass providing an opportunity to increase the importance of different geophysical methods of studying Earth’s crust for understanding modern stresses existing in it.
