Gas-dynamic roof fall during the potash deposits development

Abstract

In the development of practically all potash salt deposits, the study of gas-dynamic phenomena (GDP) is one of the most difficult tasks to ensure mining safety. Sudden salt and gas outbursts, dynamic breakdown, which are accompanied by intense gas release and possible broken rock carry-over into the mine workings, are associated with GDP. Geological preconditions for the GDP development are often the layered structure of the salt rock mass, the presence of interlayers and layers of salt clays.
 For the conditions of the Usolsky potash plant mine, complex studies of factors that characterize the possibility of gas-dynamic roof fall of the stoping rooms were carried out. In mine studies, free gases pressure and the initial velocity of gas release in the rocks of the roof workings were determined. The obtained experimental estimations were used as a parametric basis for mathematical modeling of geomechanical processes under conditions of a near-contact accumulation of free gas.
 The deformation of a layered salt mass produced by a room development system was described by the model of an ideal elastic-plastic medium with internal friction. The parabolic envelope of Mohr circles was used as a plasticity criterion in the compression area. In the numerical implementation, the deformation of clay contacts was modeled by Goodman contact elements. Based on the results of multivariate numerical calculations, it is established that the main factors determining the possibility of implementing GDP are the additional gas pressure at the contact, the width of the workingspan, and the distance from the roof to the first gas-containing contact. With multi-level lamination of roof rocks, there is a danger of large sources of GDP formation and the mechanism of successive fall of layers in an instant mode is implemented.

Modeling and Mitigating Gas Hazards during Potash Mine Closure

“…Baryakh et al [21] studied factors that characterize the possibility of gas-dynamic roof fall in the stoping rooms. The authors established that natural gases in the working-out layers, host rocks, and non-working silvinite and carnallite layers located in between the layers, roof, and soil are distributed extremely unevenly.…”

In-situ permeability testing of deep-level potash salt rocks with a view to creating water retaining walls

“…Отработка месторождений калийных солей осложняется возможностью возникновения внезапных прорывов воды в горные выработки [1][2][3][4][5][6]. Несмотря на многочисленные научные исследования и применяемые меры при строительстве и эксплуатации месторождений [7][8][9], зафиксировано множество случаев аварийного затопления соляных рудников и шахт [10][11][12][13][14][15][16][17][18]. В литературе описаны аварийные затопления рудников БКРУ-3 и БКРУ-1 ОАО «Уралкалий» в 1986 и 2006 гг., более 15 рудников в Германии («Иессенитц», «Фридрих-Франц» и др.…”

Mathematical modelling of displacement during the potash ores mining by longwall faces

“…The criterion for the roof rocks collapse was opening of the contact between the seams when shear fractures reached its boundaries or formation of a zone of tensile stresses at the outcrop [37].…”