Karaganda State Technical University, Karaganda, Kazakhsta:

K. M. Beisembaev, Professor, Doctor of Engineering Sciences, kakim08@mail.ru
N. S. Malybaev, Associate Professor, Candidate of Engineering Sciences
S. K. Tutanov, Professor, Doctor of Engineering Sciences
M. N. Shmanov, Associate Professor, Candidate of Engineering Sciences

A coal and rock mass in the course of longwalling is nonsteady. It is possible to control such coal and rock mass effectively in the mode of feedback. Instability of the face area is governed by its division into layers of different thickness, strength and deformability. The rock mass transformation can be assessed by 3 factors: spalling, transverse failure and jumps in moduli of deformation of rocks and coal. Spalling, which is estimated within sections with length equal to spacing of contacts of layers or to size of finite element, occurs jumpwise up/down the face and at various distances to the face. This can result in critical exposure of a layer, in sharp change of deformation pattern in rock mass above the longwall, in high loads applied to the coal seam and powered roof support, and in transverse failure of the layers. As a result, the influence of rocks on the face and the rock mass deformation pattern cardinally change. As a consequence, it is required to find and use another calculation scheme. The model transformation patterns can be compared with field data and with models with equivalent materials. The mechanism of influence exerted by the roof support on rock mass is detailed using 3D models with regard to possible variant of roof failure in the form of overhang rock caving, mass fall of small pieces and arching with allowance for basic production situations. The mechanism of the roof support action is substantiated, and the results of the roof support influence on the face are presented. The constructed models include blocks of linear support units with a part of the face and mined-out area; blocks of the longwall junctions with haulage and ventilation drifts. It is possible to model various combinations of blocks for longwalls, relative sliding using contact-elements for sliding surfaces cutting the longwall; with regard to pressure asymmetry; individual modeling of each support unit in the longwall.
The study was supported by the Ministry of Education and Science of the Republic of Kazakhstan, Program AR05134441: Design, manufacture and testing of new swivel block for conveyor with swing at an angle to 90 degrees in the plane of the roadway floor for longwalls and curved roadways.

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