SUMMARY:

The laws are considered of the destruction process in time in vertical shafts which are sank in high—induced rock massifs. The initial design of a shaft of a circular section is changing into an ellipsoidal cavern. Besides the dimensions of a cross section of the cavern in the horizontal plane have 10 times exceeded the initial diameter of the shaft. Characteristic destruction of shafts in the cross section in the form of ellipse fully agrees with the calculated predictions if high horizonial stresses existing in a massif are taken into consideration. The criteria and speeds are determined of the development of rock destruction in time at different relations including the overlimiting relations between strength and indices of the state of stress of rocks in the outline of shafts. A choice of a cross section of a shaft and of the disposal of adjacent workings is of great importance taking into consideration the direction of the greatest horizontal compression. In addition the intensity of destructions reduces here by the factor of 3–5 and in some cases of 10.

ZUSAMMENFASSUNG:

Man betrachtet die Gesetzmassigkeiten des Zeitzertruemmerungsprozesses von den in den hochgespannten Gebirgsmassiven abteuften Seigerschachten. Die Anfangskonstruktion des Schachtes mit runder Schachtscheibe verandert sich in ellipsenahnlicher Kaverne. In diesem Fall sind die Abmessungen des Querschnittes in der Horizontalebene zehnmal grösseren im Vergleich zum Anfangsdurchmesser des Schachtes. Die charakteristische Zerstöhrung der Schachte wird im Querschnitt nach der Ellipse mit den angerechneten Prognosen vollstëndig koordiniert, wenn man die im Massiv wirkenden grossen Horizontalspannungen beruecksichtigt. Es werden die Kriterien and die Deschwindigkeiten der Gesteinszerstöhrungen wahrend einiger Zeit bei den verschiedenen and nachaussersten Beziehungen zwischen der Festigkeit and der Kennziffer der Intensitat der Gesteine auf der Kontur der Seigerschachte festgestellt. Eine grosse Bedeutung hat fuer Stabilitatsverwahrung die Auswahl der Schachtscheibe and der Lage von Nebenverhieben in Anbetrachtder Richtung grösserer Horizontalpressung. In die— sem Fall gelangt man bis zur Verminderung der Intensitat der Zerstöhrungen um dreibis fuenfmal and in einigen Fallen bis zehnmal.

RESUME:

On examine les regilarites du processus de la destruction dans le temps d''existence des puits verticaux creuses dans les massifs rocheux haut contraints. La construction primaire du puits de la section circulaire se regenère en caverne ellipsoïdale. Dans ce cas les dimensions de la section transversale d''une caverne du plan horizontal s''est augmentee de dix fois en comparaison avec le diamètre primaire du puits. La destruction caracteristique de puits dans la section transversale sur une ellipse s''accorde completement avec les pronostics calcules, si on prend en consideration les grandes contraintes horizontales dans un massif. On a determine les critères et la vitesse du developpement de ruptures des roches dans le temps avec differentes correlations entre la resistance et les indices de 1''intensite des roches sur le contour des puits. Une grande importance pour le maintien de la stabilite a le choix de la section du puits et de la disposition des ouvrages adjacents en consideration de la direction de plus grande compression horizontale. Dans ce cas it y a la diminution de l''intensite de ruptures de Modern investigations have proved the occurence of such a pnenomenon as the tectonic state of stress of rocks in most deposits which are composed of igneous rocks and in those which are represented by sedimentary rocks of metamorphic complex. The state of stress of rocks existing in tectonically induced massifs is written as follows: the gravitation component of stresses determined by the depth (H) and volume weight (r) of rocks;

  • J - Poisson''s ratio;

  • T — the tectonic component of stresses;

  • the anisotropy coefficient in the field of tectonic stresses.

The additional component (T) of stresses in tectonically induced massifs is a compressive one and can several times exceed the component which is conditioned by the weight of overburden rocks. In most cases the vector of the additional component has a horizontal direction. It follows that in tectonically induced massifs the main horizontal stresses 6 2and in absolute value exceed a vertical one. Investigations have shown that in tectonically induced massifs rocks are highmonolithic, strong and elastic. The properties of tectonically induced massifs mentioned above condition the peculiarities of rock pressure manifestation while constructing various underground structures. When driving a working one can observe cracking and flaking of rocks. In the most induced sections of an underground structure rock bursts and burstings may take place. These peculiarities of destruction of highly-stressed rocks are considered in publication (Markov et al. 1979). Different conditions of the development of destruction process were analized in our paper at the symposium on rock mechanics (Turchaninov et al. 1981). Loss of stability of workings in tectonically induced massifs is conditioned by the process of brittle fracturing of rocks which takes place near the outline of a working and is accompanied by the forming of fractures and the caving of rock plates into the working.

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