PSI - Issue 32

A.A. Baryakh et al. / Procedia Structural Integrity 32 (2021) 109–116 A.A. Baryakhet al./ Structural Integrity Procedia 00 (2019) 000 – 000

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For the conditions of the newly commissioned Gremyachinskoye field, the displacement process has not been studied. Thus, to calibrate the mathematical model, we used the data from the Saskatchewan field, which has a similar geological structure, depth, and mining system to those of the Gremyachinskoye field. Using this rheological approach, we used mathematical modelling methods to estimate the rock mass deformation, undermined at the Nutrien Corey mine (Canada). Fig.1 shows a graph of the increase in the calculated and actual vertical displacements of the earth’s surface over time. The figure sho ws that there is a satisfactory agreement between the modelling results and field measurements.

Fig. 1. The graph of the increase in the calculated and actual subsidence of the earth’ssurface over time

Thus, the function of increasing subsidence at the earth’s surface η (t) obtained for the Nutrien Corey mine can, in the first approximation, be considered as a basis for estimating the stress-strain state of the underworked rock mass of the Gremyachinskoye deposit. To consider the differences in the geological structure and mining parameters of the Gremyachinskoye field, an elastic problem was solved to determine the subsidence of the earth’s surface caused by stoping. The relation between the obtained subsidence and the elastic vertical deformations of the earth’s surface within the Saskatchewan field was used as a correction factor for the graph of the increase in the earth’s subsidence over time ሺ ሻ .The problem was solved in the formulation of the plane deformation. The schematic diagram of the computation for the section of the underworked mass is shown in Fig. 2. The boundary conditions were determined as follows: at the lateral boundaries, the horizontal displacements were equal to zero, and at the bottom boundary, the vertical displacements taken equal to zero. The upper limit (daylight surface) was free from tractions. The proper eigenweight of the rocks was considered by setting the mass forces with intensity ( is the specific weight of the i -th element of the rheological cut). The initial stressed state of the undisturbed salt rock was hydrostatic: Ͳ ൌ Ͳ ൌ , Ͳ ൌ ͲǤ In the geomechanical model, the mined-out space was reflected by a medium with reduced mechanical properties compared to the rocks of the corresponding layer. The degree of reduction in the mechanical properties was determined by the parameters of the pillar mining system (6). The properties of the rocks occurring in the geological section were set based on the results of physical and mechanical tests performed within the Gremyachensky field. The properties of the contact were derived from laboratory data (Baryakh et al. 1992).