Structural weakening of rocks is currently studied in different aspects. The diversity of the tasks involved determines a large number of research methods. Most of them provide only an indirect assessment of the weakening of the massif and do not give quantitative dependencies of the influence of weakening of rocks on their strength and deformation characteristics in the conditions of natural occurrence.
Ring and arch supports subjected to loads may fail either from insufficient strength or from insufficient stability, which is verified by determining the critical load causing loss of stability of the structure.
At the Department of Construction of Mining Enterprises LGI developed a method of stress measurement, instruments and apparatus, which are characterized by simplicity, reliability and sufficient accuracy. The method is based on the assumption that if a sensor is placed in a borehole in a mountain massif, providing it with a good enough contact with the walls of the borehole, then as a result of the movement of the walls of the borehole under the action of the load, the sensor readings will simultaneously change. The forces acting on the sensor will decrease or increase depending on the location of the rock mass under compressive or tensile stresses.
The main parameters that need to be determined when studying the manifestations of rock pressure in shafts are the magnitude of the load on the support, the nature of its change in time and distribution along the contour of the cross-section of the shaft, as well as the magnitude of displacements of the surrounding rock massif. To determine these parameters, the best known is the VNIMI method, which is based on the use of special dynamometric bracing. More than ten years of experience in the use of such a mount has proved the performance of its main components However, the widespread use of the mount in research work is constrained, because most of the devices and equipment used in it are not mass-produced, and their manufacture in local workshops is virtually impossible. In this regard, LMI developed a simplified design of dynamometric support and measuring devices, which are characterized by simplicity and can be manufactured in mine workshops. This allows organizing instrumental observations on a much wider scale and obtaining information on the manifestations of rock pressure in the volume necessary for solving a number of practical problems.