Creep of rocks

Abstract

Creep tests on rocks performed in the laboratory are very significant in mining and in improved design of underground structures, in order to ensure safety, to increase the amount of extracted ore, etc. The simplest creep tests are the unconfined ones, when the lateral surface of the rock specimen is stress-free. Confined creep tests performed in a ‘triaxial’ apparatus where the lateral surface of the specimen is subjected to a constant pressure are seldom carried out. Sometimes the creep tests are done at elevated temperatures or, on the contrary, at lowered temperatures. The devices used to study the creep of rocks are described by several authors (see, for instance, Lama and Vutukuri (1978, Vol. III), Wawersik and Preece (1984), Kartashov (1973, §8), Hardy et al. (1984), etc.). Generally, the devices used in creep tests are now highly sophisticated (Wawersik (1975)).