Abstract
An estimation method for earthquake-induced pore water pressure and the post-earthquake settlement of soft clay was developed by focusing on its Atterberg’s limits and the direction of cyclic shearing. To clarify the fundamental characteristics of clays with different Atterberg’s limits under multi-directional cyclic shear, normally consolidated specimens of Kaolinite clay, Tokyo bay clay and Kitakyushu clay were subjected to cyclic simple shear under the undrained condition with various cyclic shear directions and shear strain amplitudes, followed by the dissipation of cyclic shear-induced pore water pressure. The effects of undrained cyclic shear on the pore water pressure accumulation and post-cyclic settlement were observed, and relationships with Atterberg’s limits were then investigated. In conclusion, the pore water pressure accumulation and post-cyclic settlement induced by multi-directional cyclic shear increase considerably to a higher level compared with those generated by the uni-directional one and such a tendency is evident for clays with a wide range of Atterberg’s limits. Comparisons of the results indicate that the soil with higher plasticity index shows the lower pore water pressure accumulation and post-cyclic settlement, irrespective of number of strain cycles and shear strain amplitude. Based on these results, a model for earthquake-induced pore water pressure and post-earthquake settlement was developed by incorporating the Atterberg’s limits as a function of experimental constants and the practical applicability was confirmed.
Highlights
When a clay layer is subjected to cyclic shear under the undrained conditions, because of the short-term cyclic loading of earthquakes and the low permeability of clayey layers, the pore water pressure is produced which is commonly called as cyclic shear-induced pore water pressure, and such a pore water pressure increase leads to the decrease in the effective stress
The pore water pressure accumulation and post-cyclic settlement induced by multi-directional cyclic shear increase considerably to a higher level compared with those generated by the uni-directional one and such a tendency is evident for clays with a wide range of Atterberg’s limits
Comparisons of the results indicate that the soil with higher plasticity index shows the lower pore water pressure accumulation and post-cyclic settlement, irrespective of number of strain cycles and shear strain amplitude
Summary
When a clay layer is subjected to cyclic shear under the undrained conditions, because of the short-term cyclic loading of earthquakes and the low permeability of clayey layers, the pore water pressure is produced which is commonly called as cyclic shear-induced pore water pressure, and such a pore water pressure increase leads to the decrease in the effective stress. When comparing the earthquake resistance of saturated clay with sand, soft cohesive soils are believed to be relatively stable because no liquefaction takes place even under strong motion by earthquakes (Hyodo et al 1994, 1999; Yasuhara et al 1992, 2001) and studies on the earthquake-induced pore water pressure and post-earthquake settlement of clay and sand are in different situations (Matasovic and Vucetic 1992; Yildirim and Ersan 2007), due to which the influence of the cyclic shear direction on the dynamic properties of clays has just been firstly mentioned by DeGroot et al (1996) and observed for Kaolinite clay by Matsuda et al (2013a, b). A model for cyclic shear-induced pore water pressure accumulation and settlement were newly developed and its applicability was confirmed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
