Estimating the influence of the technological interlayer lamination on stability of the goaf supporting elements

Abstract

Within the Verkhnekamskoye salt deposit, productive sylvinite layers are mined using chambers supporting the overlying strata with pillars of various sizes, which stability is determined by mechanical properties of rocks, mining depths, a mining plan of layers, sizes of chambers, etc. The bearing capacity of the interchamber pillars is largely influenced by conditions of the roof and soil of the chambers and, especially, by the technological interlayer. The presence of thin clay interlayers reduces the rocks stability of the roof of underground structures and causes its intense lamination and caving of the interlayer rocks, thus, increases the height of the interchamber pillars and decreases their bearing capacity. The paper presents estimates of changing loads of the pillars during the lamination of the roof of the stoping of the lower productive layer, which is obtained by the multivariate mathematical modeling of the stress-strain state of the two-layer chamber block taking into account the main features of the geological structure and geometry of the mines. The calculations were carried out for the conditions of the plane strain state. The stress state of the chamber block was described by an ideal elastoplastic medium. The thin-layered medium was described using Goodman joint elements.