変形した岩石におけるひずみ解析法 : (I) Vector Method

概要

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KARA (1966), KARA, at al. (1968), and KARA el al. (1973) had tried to analyse strain picture in deformed rocks (buckle folds and shear belts) by the vector methods, which was developed by CURRAY (1956) to analyse two-dimensional orientation data. In this paper HARA'S method (vector method of strain analysis) will be examined on the basis of numerical experiments on two-dimensional pure shear deformation. The models used here include the following assumptions: (1) The systems are composed of a finite number of initially elliptical grains and their surrounding matrix. (2) The ductility contrast between the grains and the matrix is unity. (3) All of the grains have random orientation in the initial state. (4) The initial axial rations of the grains have unimodal distributions. The initial states of the models were determined automatically in digital computer making use of a method generating pseudorandom numbers. The vector method allows us to determine the nature of large strain of rocks including a number of elliptical grains with the same ductility as the matrix. Namely, from the vector mean we are able to determined the orientation of the principal axes of strain ellipse of the mean strain in deformed rocks. And, if the average axial ratio of the grains in the initial state is determinable, we can also estimate the amount of strain from the vector magnitude.
地学団体研究会の論文
1975-03-20