Materiały konferencyjne SEP 1993 - tom 2

Underground Exploitation School '93 liąuidation of the floatings outbursts in course of driving and re-supporting the drifts as well as during the extraction; reorientation of the drifts; the mining operations shedule corrections associated with the change in the mine-geological conditions; provision for the protective coal pack in the roof layer. 2. The study of the deformations and floating outbursts mechanism by the method of simulation on the equiavalent materials The theory of rock pressure in presence of the floating boardering the drift being not sufficient, and^ taking into account the complex character of the process within the massif under development, we think it worth making use of the methods of simulations on the equivalent materials. The background of experience in simulation for vrious fields of techniąue, say, aerodynamics and hydrodynamics,provides grounds to pressume that if the model meets even roughly the demands of the theory of similarity, it is possible to obtain quite meaningful data rcflecting the qualitative side of the phenomena. In the real problem of choosing the criteria of similarity and its constants one has, in the first place,determine the main forces responsible for the major features of the process under investigation.To obtain the qulitative estimate in the first aproximation it is surfise to account for two kinds of forcess:exterior ones - weight, - and interrior ones - strains within the rock. The basie criterion of similariti which would correspond to the combined action of the forces can be deduced from the Newton *s Law and the method of heterogeneities. According to the theorem of similiarities the motion components for the similar points in both systems are bound with a creterian relation and have equal values therein: P h P h = Ne = idem (1) where P, p, L, V - force,density,length,velocity both real and simulated. The relation (1) reflects the main criterion of the dynamics similiarity and is called Newton's number - the universal law of mecanical similiriariti for aggregate action and inner strains appearing within the massif in the vicinity of the working. The transformation having been carried out, the relation (1) appears as: N h Tm • e Ym •L = K = i n V (2) where N - force over the square; 152 Tom II