Earthquake-induced residual deformation of Ariake clay deposits with leaching

It is widely known that the sensitivity ratio of Ariake marine clay increases, if the clay is leached. Therefore, it is assumed that the mechanical properties of such clay considerably change and the shear strength decreases, if it is subjected to a cyclic load as a disturbance force, like earthquakes. In the present study, dynamic deformation and strength tests, as well as consolidation tests were conducted on Ariake clay that had leached. Static shear tests were also carried out on the clay after it had been subjected to a cyclic load. The stability of man-made earth structures on Ariake clay deposits that had leached during earthquakes was investigated. Undisturbed samples of the clay sedimented in the sea area were used in all the tests. Furthermore, an earthquake-induced residual deformation analysis was also conducted on the basis of the test results described above. Consequently, the following behaviors were observed in the study. (1) When Ariake marine clay was leached, the dynamic strength decreased and the shear modulus after subjecting it to a cyclic load remarkably decreased. (2) The effect of the leaching on the behavior of Ariake clay deposits was considerable during earthquakes.     

Interfacial energies for quartz and albite in pelitic schist

Interfacial energies of quartz/quartz (qz/qz), albite/albite (ab/ab), and quartz/albite (qz/ab) boundaries in low-grade pelitic schist were determined based on measured values of dihedral angles. Three kinds of microstructures were investigated, and the interfacial energies were obtained in two independent ways. (1) Relative values of interfacial energy were calculated from dihedral angles formed at quartz and albite triple junctions. (2) Subgrain boundary energy was calculated using the Read-Shockley theory for a boundary connected to an intergranular pore. Dihedral angles formed at the corners of intergranular pores were measured. From the interfacial tension balance equation, the value of the qz/qz grain boundary energy was then obtained. (3) Dihedral angles formed at intersections of either pericline or albite twin boundaries with either ab/ab or qz/ab boundaries were measured. The twin boundary energy was calculated based on a previously derived equation using Landau potential, twin wall thickness, and critical temperature for a phase transition in albite. With a modified interfacial tension balance equation for a twin boundary fixed to a facet orientation, the interfacial energies of ab/ab and qz/ab boundaries were obtained. Energies obtained by methods of (2) and (3) are in good agreement. The interfacial energies for qz/qz, ab/ab, and qz/ab boundaries obtained in this study are 270뀶, 300끞, and 250끀 mJ/m², respectively.