This paper presents some considerations of research on the stability of underground storage caverns in rock. At the beginning the author introduces a conception of transformations and distribution of energy in rocks confining the cavern and proposes an approximate equation of conservation of energy which is a fundamental criterion to be followed for studying and controlling the stability of a cavern. Then, relating to a research work of a 40-meter-span cavern in China, this paper discusses some problems concerning the measurements of earth stress in the field, the non-linear finite element analysis and finally, the analytical method used for evaluating the fracture zone of rock mass and so on. At the end of this paper a great deal of numerical analogic computation with finite element method for studying the stability analysis of a cavern with various joint systems in various stress field is listed. Some significant conclusions for se~ting the site and location of a large span cavern as well as for design and construction of the support are given.
In der vorliegenden Arbeit handelt es sich um einige Probleme ueber die 5tabilitat der unterirdischen Lagerfelshöhle im Felsen. Zuerst fuehrt der Verfasser einen Gedanken der Energieuebertragung und Energieverteilung um die Felshohle ein und dann stellt eine Naherungsgleichung der Energieerhal tung vor, welche als grundliegendes Kriterium fr die Untersuchung und Kontrollierung von der Stabilitat der Felshöhle gilt. In Verbindung mit einer Untersuchungsarbeit von einer weit gespannten Felshöhle mit 40 Meter 5pannweite in China der Verfasser untersucht einige Probleme, welche die Gebirgedruckmessung auf dem Feld, nicht-lineare endliche Elementenanalyse und die analytische Methode des Kriteriums fUr die Bruchflache und den Störungsbereich der Felsenmasse und des Gebirgskorpers. Am Ende dieses Beitrags ist eine groGe Anzahl von numerischen Berechnungen mit der Finite Elementmsthode als Parameterstudie zur Standsichsrheitsberechnung einer Kavsrne mit verschiedenen Trennflachengsfuegsn und Spannungsfeldern aufgefuehrt. Einige wesentliche Schluesse fuer dis Standortwahl großer Kavernen absr auch fuer den Entwurf und die Konstruktion der Sichsrungen werden gezogen.
On presente certaines considerationsde recherche sur la stabilite des cavernes souterraines de stockage. D''abord, les conceptions de transformation et de repartition de l''energie dans Ie massif rocheux entourant une caverne souterraine sont controduites1 l''auteur avance une equation approximative de la conservation de l''energie qui est consideree comme un criterium fondamental suivi pour analyser et contrôler la stabilite d''une caverne souterraine de grande portee de 40 m en Chine, on discute certaines considerations, y compris la mesure in situ de contrainte, l''analyse non-lineaire d''elements finis, la methode analytique utilisee pour juger la zone de fracture des massifs rocheux, etc.. Enfin, au moyen de calcul analogi que de beau coup de numeros avec la methode d''elements finis de stabilite des massifs rocheux entourant une caverne souterraine avec les systemes de joints varies dans les champs de contraintes variees, certaines conclusions significatives pour Ie choix de site et de ligne de caverne souterraine de grande portee ainsi que pour Ie projet et Ie construction du support sont donnees.
The problem of stability of underground cavern is one of the practical subjects of rock mechanics. That course, as the whole of rock mechanics, is lack of ripe theory and methods for study. There are various factors to effect the stability of an underground cavern, the essential components can be summarized as follows: effect of geology (especially geological structure). effect of geo-stress state, effect of the mechanical properties of rock mass. engineering effect involving the shape of cavern and the technique of underground excavation and effect of underground water etc. For the rock mass is a complex body. it is almost impossible to establish a complete theory that is suitable for every conditions to get a quantitative solution. Therefore. at the present stage. the more reasonable way is that to classify the problems with different characters into different categories, to simplify them and to resolve them in approximately way separately. This paper will present the main points briefly of our research for several problems.
It is well known that most rock formations unexcavated possess distinct elastic properties and therefore comprise of elastic potential energy. Mechanical effects such as deformation, fracture etc. in the confining rock after excavation may be regarded as the results of the work done by the release of potential energy. The rock mass has been analysed as homogeneous, linear elastic body by N.G.W. Cook and M.D.G. Salamon. The latter formulated the energy conservation equation, We+Um=Uc+W" in which We is the work done by the internal stress, built up within the total volume of the confining rock during excavation, Umis the strain energy released from the excavated portion of the rock mass, Uc is the strain energy newly accumulated in the immediately adjacent confining rock due to excavation, and W, is the loss of elastic energy in the process of excavation.
