PSI - Issue 32

I S Lomakin et al. / Procedia Structural Integrity 32 (2021) 117–123 I S Lomakin, A A Tsayukov / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 4. Changing loadings of the pillars during lamination and caving of the roof rocks of the lower productive layer.

3. Results of Modeling The geomechanical calculations were a series of the numerical experiments in the form of a step-by-step procedure. At each step, the problem of determining the size of the caved roofing part was solved in accordance with the accepted criterion for the caving of the rocks in the interlayer. After that, the model of the chamber block was rebuilt taking into account the caved part, and the calculation was performed using a new one. So it will take place until a vault of the chamber is formed, at which the criterion of the rock caving will not be fulfilled.As an illustration, Fig. 4 shows the results of the described computational procedure for the first variant ofcalculations. As a result, the combined thickness of caving the interlayer rocks reached 0.6 m. The pillar loading in the lower productive layer, estimated by formula (5), at the last step was 0.476, which corresponded to an increase of 25 % from the initial value; on the upper productive layer it was 0.369, which corresponded to an increase of 9 %. In this case, the opening of the contacts occurs up to the bottom of the sylvinite layer located in the interlayer. Similar