PSI - Issue 32

N.A. Samodelkina et al. / Procedia Structural Integrity 32 (2021) 173–179 N.A. Samodelkina / Structural Integrity Procedia 00 (2019) 000 – 000

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criterion,as p p s k /    . The horizontal dashed line in Fig. 4 shows the displacements at which the contact decompaction begins ( 0,2  s p   ). As already noted, the danger of the over-saline water penetration into the WS is associated with the contact opening at the edge of the wedge-out zone (point t =0 in Fig. 4). From the analysis of the shear displacements along the contact, it can be seen that two areas are distinguished where the displacements reach their limiting values. The most pronounced of these is associated with the edge of the mined-out space. The second one is located in the wedge-out zone of the undisturbed mass and reflects a distant interaction of the mining operations with the wedge out zone. The degree of impact of the stoping on the contact between the OSR and CSZ in the wedge-out zone, along with the implemented deformations of the undermined mass, is also determined by the location of the goaf boundary in relation to it. The computations carried out for various values of subsidence of the earth surface made it possible to determine the zones of the contact loosening between the OSR and CSZ, depending on the position of the goaf boundary. Based on a generalisation of all the calculation results, a nomogram was constructed to determine the permissible parameters of the mining operations in the wedge-out areas (Fig. 5). If, at a given position of the goaf boundary ( t ) and the predicted maximum subsidence of the earth surface (  ), the point with coordinates (  , t ) falls into the area shaded on the nomogram, then it is assumed that the contact of the OSR and the CSZ is decompacted and the oversaline water can reach the top of the CSZ in the area represented by a complete cut of WS. Otherwise, there is no danger of oversaline water penetration.

Fig. 5. Nomogram of determining permissible parameters of mining operations

4 Conclusions All of the computations were carried out for the average mining and geological conditions of the Verkhnekamskoye potash salt deposit. It is advisable thatgeomechanical modelling is performedwith safety estimations of the constituent elements of the geological section in each specific case, in order to mine potash salt deposits in the zones of anomalous structures of the WS, in the form of wedging in its middle and upper parts. Acknowledgements The work was carried out with the financial support of JSC VNIIGalurgiya and the State Budgetary Assignment № 075 -03-2021-374, «Research on deformation and failure pattern of quasi plastic rocks under complex loading