1963 年 72 巻 1 号 p. 1-7
Rock mechanics is a branch of science put forward very recently by several researchers_ It shows good promise of benefit to economization and security of various ground engineering projects such as works for roads, tunnels, dams, mines, drills, reclamations, etc. In these connections, rock mechanics is a younger sister of soil mechanics. Indeed there is no apparent boundary between them. The sediments of young geological ages may be treated as soils, but in view of subconsolidation due to grain to grain bond by water, they appear as. aelotropic plastic solids. Experiments prove almost perfectly plastic behaviour of these materials. This nature may be ascertained by the fact that the bond cannot be hardened under the due deviatoric stress.
The crystallogenic rocks to the contrary have been supposed to be brittle rigid substances, ., but for that those under high geostatic pressure act as plastic body like metals. All the rocks are creepable subjects. Although the rate of flow in creep is very slow, it seems to be the principal process that makes folded structures. Therefore, the rock creep is a phenomenon of paramount interest in pure scientific aspect of rock mechanics. The knowledge will be useful in oil and gas exploration.
Rock mechanics is more intimately connected with geology than with the other related sections of science, for not only the rock masses are heterogeneous and aelotropic, but they have complex fracture systems including clefts with crushed and pulverized substances. The precise analysis of the system may be helpful in prospective work for the underground resources.
In the mathematical analysis, we will adopt the generalized tensor notation for convenience sake instead of classical farmalities. Also application of Cartesian tensor analysis may be appreciated. Outdoor observation and model testing are pari passu important approaches to the larger objects in geological scale, but executions of laboratory experiments by means of extensive modern scientific equipments are very desirable.