Dynamic Centrifuge Testing of Slickensided Shear Surfaces

Christopher L. Meehan¹; Ross W. Boulanger²; J. Michael Duncan³

¹Assistant Professor, University of Delaware, Dept. of Civil and Environmental Engineering, 301 DuPont Hall, Newark, DE 19716, U.S.A.
E-mail: cmeehan@udel.edu (corresponding author)
²Professor, University of California, Davis, Dept. of Civil and Environmental Engineering, Davis, CA 95616, U.S.A.
E-mail: rwboulanger@ucdavis.edu
³Univ. Distinguished Professor, Virginia Tech, Dept. of Civil and Environmental Engineering, 200 Patton Hall, Blacksburg, VA 24061, U.S.A.
E-mail: jmd@vt.edu

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Journal of Geotechnical and Geoenvironmental Engineering, 2008, Volume 134, Number 8, pp. 1086-1096

Abstract
Movement along preexisting slickensided rupture surfaces in overconsolidated clay and clay shale slopes can represent a critical sliding mechanism during earthquakes. The seismic behavior of preexisting slickensided surfaces in overconsolidated clay was examined by performing dynamic centrifuge model tests of two slickensided sliding block models constructed using Rancho Solano lean clay. Dynamic shear displacements were concentrated along the preformed slickensided surfaces. The peak shear resistances mobilized along the slickensided surfaces during dynamic loading were 90-120% higher than the drained residual strength measured prior to shaking. To accurately predict the displacements of the sliding blocks using Newmark’s method, it was necessary to use dynamic strengths that were 37-64% larger than the drained residual strength of the soil. Dynamic loading caused a positive pore pressure response in the soil surrounding the slickensided planes. The postshaking shear strengths were 17-31% higher than those measured prior to shaking.

Keywords
Dynamic stability; Clays; Residual strength; Slope stability; Earthquakes; Soil deformation; Shear strength; Overconsolidated soils; Centrifuge

Reference
Meehan, C. L., Boulanger, R. W., and Duncan, J. M. (2008). “Dynamic Centrifuge Testing of Slickensided Shear Surfaces.” Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 134(8), 1086-1096. (doi:10.1061/(ASCE)1090-0241(2008)134:8(1086))

DOI
10.1061/(ASCE)1090-0241(2008)134:8(1086)