The report proved the necessity of taking into consideration the solid rocks strength reduction in the area around mine workings. For this purpose it is recommended to investigate physicalmechanical properties of rocks using both samples taken from the face of the working to be driven or cores of exploratory workings and the rock samples selected in the roof, sides and floor of the mine working not long after its driving. A method and results of investigations are given to show the variability of the physical-mechanical properties of rocks surrounding mine workings at the mines of the Donbas and Karagande basins.
Im Referat wird die Notwendigkeit der Festigkeitsminderung der Felsengesteine um die Abbaue begruendet. Es wird vorgeschlagen, die physikalischmechanischen Eigenschaften der Gesteine nicht nur nach Proben aus dem Ort oder nach Kernproben der Schuerfbohrungen zu untersuchen, sondern auch nach Proben, die den Ober- und Seitenstöβen wie auch dem Liegenden einige Zeit nach dem Auffahren entnommen werden. Es werden die Methodik und die Untersuchungsangaben der Veranderung der physikalisch-mechanischen Eigenschaften der Gesteine um die Abbaue in den Gruben der Donezker und Karagandaer Reviere angegeben.
Dans Ie present rapport on prouve avec evidence la necessite de tenir compte de l''abaissement de resistance des roches avoisinantes autor des ouvrages miniers en exploitation. Dans ce but, on propose d''effectuer un examen des proprietes physico-chimiques des roches non seulement d''apres les echantillons preleves dans Ie front de taille de l''ouvrage que l''on creuse, ou selon des carottes des sondages, mais aussi suivant les echantillons pris dans Ie toit, les epontes et Ie sol de l''ouvrage quelque temps apres son creusement. On presente la methode et Ie resultats de l''examen de changement des proprietes physico-chimiques des roches avoisinantes autour des ouvrages miniers dans les mines des bassins de Donetzk et de Karaganda.
Observations on rock behaviour on contour of workings show changes of rock strength in the course of time. Thus, we observed the cases when at first a working was driven in strong rocks, but later the rocks on contour turned into clayey mass which can be easily separated from rock mass by hand. As a rule, increased rock pressure and deformation of supports occured in such workings. while widening workings the lowest rock strength was observed on their contour. Rock strenght increased, with the distance from the contour being increased. To choose the type of support and to solve some other problems it is impotant to know changes of rock properties in time their stability. In this connection we investigated the changes of rock properties in mine workings of Karagande and Donetz basins. In the first stage as the size of rock zone around the working in the limit of which the properties of rocks were changing was unknown the samples were taken by drilling cores 45 mm in diameter at the distance of 2 m from the contour of working. Later studies showed that changes of rock properties took place at the distance of not more than 1 m from the contour of working section. In this case driving with pneumatic hammer appeared to be the simplest way of coring. Before coring the working section contour surface was thoroughly examined, planes of bedding determined and then cores were taken on the working contour and at different distances from it. Coring'' was done by gradual winning of rock seam with pneumatic hammer to the rise and to the dip.
