Materiały konferencyjne SEP 1993 - tom 2

Szkoła Eksploatacji Podziemnej *93 g - rocks specific weight; L - geometrie dimenshions. It should be noted that in G. Kuznetsov's /3/ oppinion it is possible to calculale the bułk and resilient materials using the simplified ideas as to thcir boundary conditions. They are characterized by certain constant values of the bounding force C, having parametres and coefficient tg (p, where (p - is the angle of the inner friction. Thus: (3) H » ^ 1 'im ^ Cm = r — C YH 9 M = fg «PH (4) Bearing in mind the peculiarity of the present simulation in various rocks both solid (coal layer) and floating let us make use of the fonnulas (2),(3),(4) for choosing the equivalent materials. The invesligations carried out by the author with assistance of A. Trubakoy (post-graduate) aimed at determining of the inncr friction angles within the dry and wetted rocks (various sands of the overcoal mass) proved that the spread of values is within the limits of 3% (tablc 1). Table 1 Sands characleristics by the inner friction angles Slate of rocks Sands inner friction angle Kiev KharkoY Poltava Lower Neogcne Upper Neogene River Dre, degrees 35M0 33''50 3 r o o 25''30 34^20 30'36 Water covered, degrees 34M0 32 "50 29"! 0 23M5 33''50 30°34 Thus, to simulate the wetted sands it is possible to use sands dried to the extent when ihe inner friction angle is most close to that in wetted siate. The bounding force among the particles can be neglected as this value for Uie loose wetted and dry bulky rocks is extremcly smali and in the simulation scalc 1:10 approaches zero value. The choice of the equivalent materials and the calculation of their mechanicał propcrties account for the fact that the brown coal posesses Iow strength chan>cleristics. According to: KT ^ Tvr (5) it is possible to bring up the strength properties of the model materiał, which is not expedient. So the materiał with greater volume mass than that of the real one was searchec! for. For this purpose the dispersed mix of Si and Fe was found (ferro-silicon) Sekcja III 153