Influence exerted by underground excavation shape and by effective stresses on the formation of a tensile strain zone at a depth greater than 1 km [ОЦЕНКА ВЛИЯНИЯ ФОРМЫ ВЫРАБОТКИ И ДЕЙСТВУЮЩИХ НАПРЯЖЕНИЙ В МАССИВЕ НА ФОРМИРОВАНИЕ ЗОНЫ РАСТЯГИВАЮЩИХ ДЕФОРМАЦИЙ НА ГЛУБИНЕ СВЫШЕ 1 км]

The article presents the studies into the secondary stress field formed in surrounding rock mass around underground excavations of different cross-sections and the variants of principal stresses at a mining depth greater than 1 km. The stress–strain analysis of surrounding rock mass around development headings was performed in Map3D environment. The obtained results of the quantitative analysis are currently used in adjustment of the model over the whole period of heading and support of operating mine openings. The estimates of the assumed parameters of excavations, as well as the calculations of micro-strains in surrounding rock mass by three scenarios are given. During heading in the test area in granite, dense fracturing and formation of tensile strain zone proceeds from the boundary of ε3 ≥ 350µε and is used to determine rough distances from the roof (Hroof) and sidewalls (Hside) of an underground excavation to the boundary ε3 = 350µε (probable rock fracture zone). The modeling has determined the structure of secondary stress and strain fields in the conditions of heading operations at great depths. © 2020 Publishing house Mining book. All rights reserved.