Abstract
The frame of a triaxial specimen was established by measuring the three-dimensional coordinate in the images obtained using two methods. In the “8 Cameras” Method, 8 digital still cameras were used. In the “Rotated Specimen” Method, only one camera was used and all surfaces of a specimen were captured by rotating it. The accuracy of the coordinate measurement was 0.05mm in both methods. In order to analyze the shear band in a drained triaxial test, the details of the shear band was extracted by the three-dimensional coordinates measured in all surfaces of the specimen and the continuous change of the void ratio in the shear band was estimated. The results revealed that the void ratio of the shear band in Toyoura sand exceeded the maximum void ratio in the residual stress state. Moreover, in the post-peak stress state, the shear band of Masado was observed to form with decreasing thickness.
