ABSTRACT:

In this paper, subcritical crack growth of granite at highslope of the Three Gorges shiplock had been studied first. By using dislocation density concept in damage mechanics, rheololgical growth of a crack was generalized into multi-joint rocks, and a rheological damage fracture model for jointed rocks was obtained. Based on this model, the highslope of the shiplock had been analyzed with finite element method. At present, the Three Gorges shiplock has been in construction for about 3 years. The results in this paper were compared with the measurement values, and they coincide with each other very well.

RÉUMÉ:

: La croissance de crique sous-critique de granite des talutages hauts de l'ecluse de navigation dans les Trois Gorges a ete etudiee. Par generaliser la conception de la croissance de crique rheologique dans l'etude sur la roche des multi-cassures, un modele de crique de dommages rheologiques a ete base sur la theorie de la densite de dislocation. Trois ans apres que l'ecluse de navigation a ete construite, une comparaison entre les mesures in situ et les analyses par elements finis aux talutages hauts, effectuee suivant les recommandations donnees dans cet article, a conforme la validite de ces recommandations.

ZUSAMMENFASSUNG:

In der vorliegenden Arbeit wird die unterkritische Granit-Rissbildung der Hochgesteinhange zuerst untersucht. Auf Grund des Konzeptes ueber DislocationsdensitAt in Besadigungsmechanik und der Anwendung des rheologischen Rissbildungsprinzipes wird ein rheologisches Beschadigungmodell fuer Multi-Joint-Gestein entwickelt. Auf der Basis des Modells wird die Hochgesteinhange mit FEM studiert. Die Ergebnisse werden mit den Messungsdaten verglichen und die beide sitimmen gut ueberein.

INTRODUCTION

The Three Gorges shiplock is under construction and has been excavated in high mountains. The maximum height of the slope of the shiplock is nearly 170m. The straight wall of the shiplock chamber extends 50–70m. With excavation of the shiplock, geostresses of rock masses in the slope were released, and instantaneous, time-dependent deformations and redistribution of geostresses appeared. Because the shiplock is very important and requires high quality of operation, the authors have proposed a model of rheological damage fracture for jointed rock masses to analyze the stability of the highslope.

Rock crack growth exhibits time-dependent characteristics when the values of stress intensity factors are lower than that of rock fracture toughness. Based on this point, subcritical crack growth of granite at the highslope of the Three Gorges shiplock had been studied by using double torsion specimens and the parameters of fracture toughness and crack growth were gained from experiments. Thus, by means of dislocation density concept in damage mechanics, the growth of a crack was generalized into multi-jointed rock masses. According to the theory of thermodynamics, a rheological damage fracture model for jointed rock masses was obtained. Based on this model, the highslope of the shiplock had been analyzed with finite element method. And accordingly back analysis was performed and the mechanical parameters of the rock masses were obtained. At last, using the parameters deduced from back analysis, authors predict the displacement and stability of the shiplock of the Three Gorges

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