A method for the prognosis of mechanism of deforming and destroying in a stratified mine roof is described. The method concerning near rooms driven in sedimentary rocks includes the real pattern strength of rocks. The practical direction of this report including the use of its results for the estimation of the stability of rooms erected underground is shown.
Es handelt sich um eine Prognose der Verformungen und Zerstörungen des vielschichtigen Hangendgebirges ueber den benachbarten Kavernen im Sedimentgestein mit Anwendung der reellen Festigkeitskennwerte der Gesteine. Es wird eine praktische Bedeutung dieser Arbeiten hervorgehoben, einschließlich der Anwendung ihrer Ergebnisse fuer die Beurteilung der Standsicherheit von untertagigen Kavernen.
La methode de la prediction du mechanisme de la deformabilite et de la destruction des formations multi couches du toit est consideree conformement aux chambres rapprochees dans les roches sedimentaires avec l''utilisation de la solidite reele des roches. La tendance pratique des recherches en question parmi eux l''utilisation leur resultats pour l''evaluation de la stabilite des chambres souterrains est notee.
The mechanical processes, occuring in a solid when underground workings are driven through it depend, to a great extent, upon the heterogenity of the solid structure as well as on the presence of surface weakening and fracturing. The weakened contacts in sedimentary bedded solids possess little cohesion with the angles of friction being small. These features are to be taken into account when solving the problems connected with rock stability estimation, the prediction of the breaking points within the cover of the solid and the choice of the type of support in workings being also taken into consideration.
A number of analytical and experimental investigations in this field were carried out by Kuznetsov (1961), Mc Niven and Ewoldsen (1969), Rachimov (1980).
The paper studies some aspects of the prediction in the roof-rock breaking processes of underground chambers. These processes commence under the influence of the tangential stresses due to the shear, (the processes are commonly known as lamination). Sometimes they are due to scaling when the contact relations of the adjacent (strata) layers are disturbed. Extended are the conceptions previously advanced by Donzyl (1974, 1975), Kuznetsov (1968), Kuznetsov, Filatov, Donzyl (1980), i.e. the authors of the paper.
The complex problem of elasticity theory dealing with the stress-strain condition of the heterogeneous roof of adjacent chambers is solved by two methods. At first the calculation for initial rock lamination is performed, then the rock scaling possibility is determined.
(figure in full paper)
The roof considered consists of two layers. The bottom layer (I) represented by the strip has h 1 thickness and the upper layer (II) simulated by half-plane stretches to the surface through the whole H (m) rock cover. The elastic modulus and Poisson''s ratio for both layers are considered to be known.
Since the stability between the layers mentioned is essentially less than that of the layers themselves, the slot is formed in mining, its d length being equal to 2 (ι - ι°). The slot position is unknown beforehand and it wants estimating.