Mechanical and hydraulic properties of Nankai accretionary prism sediments: Effect of stress path
Article first published online: 30 OCT 2012
©2012. American Geophysical Union. All Rights Reserved.
Geochemistry, Geophysics, Geosystems
Volume 13, Issue 10, October 2012
How to Cite
2012), Mechanical and hydraulic properties of Nankai accretionary prism sediments: Effect of stress path, Geochem. Geophys. Geosyst., 13, Q0AD27, doi:10.1029/2012GC004124., , and (
- Issue published online: 30 OCT 2012
- Article first published online: 30 OCT 2012
- Manuscript Revised: 21 SEP 2012
- Manuscript Accepted: 21 SEP 2012
- Manuscript Received: 24 FEB 2012
- critical state soil mechanics;
- triaxial deformation
 We have conducted triaxial deformation experiments along different loading paths on prism sediments from the Nankai Trough. Different load paths of isotropic loading, uniaxial strain loading, triaxial compression (at constant confining pressure, Pc), undrained Pc reduction, drained Pc reduction, and triaxial unloading at constant Pc, were used to understand the evolution of mechanical and hydraulic properties under complicated stress states and loading histories in accretionary subduction zones. Five deformation experiments were conducted on three sediment core samples for the Nankai prism, specifically from older accreted sediments at the forearc basin, underthrust slope sediments beneath the megasplay fault, and overthrust Upper Shikoku Basin sediments along the frontal thrust. Yield envelopes for each sample were constructed based on the stress paths of Pc-reduction using the modified Cam-clay model, and in situ stress states of the prism were constrained using the results from the other load paths and accounting for horizontal stress. Results suggest that the sediments in the vicinity of the megasplay fault and frontal thrust are highly overconsolidated, and thus likely to deform brittle rather than ductile. The porosity of sediments decreases as the yield envelope expands, while the reduction in permeability mainly depends on the effective mean stress before yield, and the differential stress after yield. An improved understanding of sediment yield strength and hydromechanical properties along different load paths is necessary to treat accurately the coupling of deformation and fluid flow in accretionary subduction zones.