PSI - Issue 32

113 5

A.A. Baryakh et al. / Procedia Structural Integrity 32 (2021) 109–116 A.A. Baryakh et al./ Structural Integrity Procedia 00 (2019) 0 0 – 00

Fig. 2.Schematic diagram

3. Estimation of deformations of the e arth’s surface The analysis of the deformation processes of underworked masses is a critical task associated with the protection from the negative impact of mining of facilities at the earth’s surface. The occurrence of strong and rather rigid strata (carbonate, dolomite) overlying the salt rocks is characteristicof the conditions of the Saskatchevanskoye and Gremyachinskoye fields. Their presence affects the process of deformation of the rock mass, predetermining the possibility of lamination at the contacts of the layers (strata) with a rough alteration in deformation properties. Fig. 3 shows the predicted graphs of the subsidence of the earth’s surface along the calcu lated profile at various points in time until the completion of the displacement process at the Gremyachinskoye field. Fig. 4 illustrates the nature of the rock mass lamination along the boundary between the salt and dolomite strata. The shift of the maximum displacement trough in the lateral direction at the initial time intervals (Fig. 3, С urve 1) follows the order of mining of the selected blocks. Twenty years after mining is started (Fig. 3, Fig. 4, С urve 4), due to the destruction of the bearing elements of the pillar mining system, lamination occurs at the contact between the salt stratum and the overlying dolomite deposits. From this moment on, the subsidence rate of the earth’s surface slows down significantly, and an increase in the amplitude of lamination ( δ ) along the lower boundary of the dolomite layer is observed (Fig. 4, Curve 5). At the end of the displacement process, subsidence (Fig. 3, Curve 6) reaches around 0.9 metres, and the amplitude of the contact opening decreases (Fig. 4, Curve 6). The boundaries of the zone of influence of the excavation of the productive stratum on facilities located at the earth’s surface are usually delimited by the slope of the displacement trough - ൌ ͲǤͷ ∗ ͳͲ − ͵ and horizontal deformations - ൌ ͲǤͷ ∗ ͳͲ − ͵ . In this case, with a coefficient of ore extraction from the bowels ൌ ͲǤ͵ͳ , the boundary angle is 73 0 . Let us note that in the real practise of developing potash deposits, the boundary angle is often less than 55-60 0 . An increase in the boundary angle of the subsid ence trough of the earth’s surface due to the greater