Slow episodic shear of granular materials regulated by dilatant strengthening

Research Article| September 01, 2002 Slow episodic shear of granular materials regulated by dilatant strengthening Peter L. Moore; Peter L. Moore 1Department of Geological and Atmospheric Sciences, Iowa State University, Ames, Iowa 50011, USA Search for other works by this author on: GSW Google Scholar Neal R. Iverson Neal R. Iverson 1Department of Geological and Atmospheric Sciences, Iowa State University, Ames, Iowa 50011, USA Search for other works by this author on: GSW Google Scholar Geology (2002) 30 (9): 843–846. https://doi.org/10.1130/0091-7613(2002)030<0843:SESOGM>2.0.CO;2 Article history received: 14 Feb 2002 rev-recd: 17 May 2002 accepted: 23 May 2002 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Peter L. Moore, Neal R. Iverson; Slow episodic shear of granular materials regulated by dilatant strengthening. Geology 2002;; 30 (9): 843–846. doi: https://doi.org/10.1130/0091-7613(2002)030<0843:SESOGM>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Slow, stable shear of granular materials in landslides, beneath glaciers, and along fault surfaces is common, despite little or no intrinsic strengthening of such materials with increasing deformation rate. Compacted, water-saturated sediments, subjected to constant stresses in a ring-shear device, sheared slowly without unstable acceleration in repeated episodes that included pore dilation during shear, attendant pore-water-pressure decline, and consequent strengthening, followed by gradual pore-pressure recovery and weakening. Time-averaged shear velocities (2–800 mm/d) depended inversely on the magnitude of pore dilation with shear and were significantly lower for fine-grained sediment than for coarse-grained sediment, owing to different rates of pore-pressure diffusion in the two materials. When sediment had dilated to its critical-state (steady) porosity and therefore could not dilate further, shear accelerated catastrophically. These data indicate that pore-pressure decreases and consequent strengthening caused by shear-induced dilation may not only suppress rapid shear of landslide debris, subglacial till, and fault gouge, but may also result in slow episodic shear at rates that depend on both material porosity and hydraulic diffusivity. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.