Browsing by Subject "numeric modeling"

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Access status: Open Access ,
Analiza numeryczna migracji metanu z warstw spągowych do wyrobiska ścianowego
(2007) Kwaśniewski, Marek Andrzej; Lasek, Stanisław
A two-dimensional numerical model of a large (1000 × 200 m) part of the rock masses in the vicinity of coal seam 349 in longwall panel 802 in region B in the Murcki colliery was built using the distinct element code UDEC. Longwall mining of this seam with roof caving was simulated in the model over a length of 450 m. It was found that migration of methane from coal seams lying beneath the mined seam is possible under conditions where the floor strata deform to a great extent, undergo separation, fracture and break into blocks. It was revealed that the fractured zone in thin floor layers built of weak rocks develops more rapidly than the caving zone over the minedout area and reaches a depth of about 30 m below the seam. The floor strata undergo an intense heave towards the mined-out area. Even at the early stages of mining, the upward movement of the strata exceeded 1.5 m. Under the assumption that (i) methane-bearing strata occur 15.6 m below seam 349 and include seam 350 and the strata lying beneath, and (ii) the methane reservoir pressure is equal to 2 MPa, the direction, pressure, quantity and velocity of the methane flow through cracks developing in the floor strata under the area of seam 349 being mined were investigated.
Access status: Open Access ,
Projekt zabezpieczenia komory »Ważyn«
(Wydawnictwa AGH, 2005) Chmura, Janusz; Lasoń, Andrzej
Several hundred years long mining perforated considerably the underground rock mass of Bochnia. Damaging influence of time has resulted in advancing destruction of a unique, historic salt mine, shaped by many generation of Bochnia miners. The advancing alterations of the »Ważyn« underground chamber are a spectacular example of destructive changes within the rock mass. Convergence of excavations is much more pronounced in the Bochnia salt mine in comparison with the salt mine in Wieliczka: the underground deformations result from different geological structures of both mines. Protecting old excavations is a must if the historic substance of this unique mine is to be preserved. This assumption was a basis of investigations on how to protect the »Ważyn« chamber.