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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The fulfilment of the inequality was the condition for softening (opening) of the contact (the phenomenon of dilatancy) s m    , where s  is the shear displacement of the contact edges; p  is the shear displacement corresponding to the peak strength of the contact p  , and *  is the residual strength. The value of coefficient m was estimated based on the results of experimental laboratory tests[Baryakh et al., (1992)]: m =(0.20-0.45). During the calculations, the distance from the goaf border to the wedging-out boundary was varied 550 550    t m, atintervals of 50 m. The positive values of t indicate that the boundary of the mined-out space is located in the area of an incomplete section of the WS - to the right of the wedging-out boundary; the negative values are located in the area of a partially incomplete or complete section of the WS - to the left of the wedging-out boundary. The solution to each option was carried out for the following values of the maximum subsidence of the earth surface  = 0.5 m, 1.0 m, 2.0 m, 3.0 m, 4.0 m, and 5.0 m. 3. Results of Multivariate Mathematical Modelling and Analysis It follows from the problem formulation that the danger of mining in the wedge-out area is associated with shear deformations of the contact between the OSR and CSZ, during which dilatancy may occur. The deformation value of a contact is determined by the stresses acting on it, both normal and tangential. In this case, the tangential component works to increase shear deformations and the normal component prevents their manifestation. p

Fig. 3. Distribution of the normal n  (a, b) and tangential s  (c, d) stresses along the contact of the CSZ with the OSR and SMS, depending on the position of the goaf boundary and the subsidence value of the earth surface