Pre-existing Planes Of Weakness Research Articles

Analysis of Fracturing in Precambrian Volcanics North of Madoc, Ontario

This paper presents a study of joints and other systematic fractures in Precambrian metavolcanic rocks. Although the mechanism that created the complex array of joints is not clear, one can deduce that they served as pre-existing planes of weakness during a later period of deformation in which slip occurred along both joints and systematic fractures. One consequence of this movement was an adjustment of rock material at the junction of intersecting fractures. An 'adjustment surface' was created at specific fracture intersections by movement of adjacent joint blocks toward one another. This 'adjustment feature' is a structural element, which can be utilized in reconstructing the principal stress directions of the later period of deformation.

Tension Tests on Layered Rocks

Research Article| February 01, 1969 Tension Tests on Layered Rocks YOUNATHAN YOUASH YOUNATHAN YOUASH Department of Geology, University of Baghdad, Adhamiya, Iraq Search for other works by this author on: GSW Google Scholar Author and Article Information YOUNATHAN YOUASH Department of Geology, University of Baghdad, Adhamiya, Iraq Publisher: Geological Society of America Received: 09 May 1966 Revision Received: 30 Jul 1968 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1969, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1969) 80 (2): 303–306. https://doi.org/10.1130/0016-7606(1969)80[303:TTOLR]2.0.CO;2 Article history Received: 09 May 1966 Revision Received: 30 Jul 1968 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation YOUNATHAN YOUASH; Tension Tests on Layered Rocks. GSA Bulletin 1969;; 80 (2): 303–306. doi: https://doi.org/10.1130/0016-7606(1969)80[303:TTOLR]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 SocietyGSA Bulletin Search Advanced Search Abstract Tension tests were performed on four layered rocks: a shale, a gneiss, and two sandstones. Cores 2.125 by 4.25 inches were prepared, with the layers dipping at 0°, 15°, 30°, 45°, 60°, 75°, and 90° to the short cylinder axis. All tests were carried to failure, and strain was measured by gauges mounted on the cores.Rupture strength in tension is highly affected by the orientation of layering. In general, as the dip of the layers increases, the rupture strength increases correspondingly. For 0° to 60° cores, failure occurs along layering; for 75° and 90° cores, failure occurs across layering. Rupture strength in tension is lower if failure occurs along layering than if it occurs across it. Therefore, it is postulated that during rock deformation, if rocks are subjected to tension, it is more likely that failure will occur along pre-existing weakness planes, such as joints, faults, bedding, lamination, and foliation, than for failure to occur across layering and weakness planes.The different theories of failure which assume that material is homogeneous and isotropic, whether in tension or in compression, are not applicable on rocks that are characterized by definite planes of weakness and anisotropy. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.