Cohesion (or adhesion) and friction angle in direct shear tests

April 1, 2009

A technical note regarding interpretation of cohesion (or adhesion) and friction angle in direct shear tests By Richard Thiel Introduction Direct shear testing with geosynthetics is generally performed in accordance with ASTM D5321, Standard Test Method for Determining the Coefficient of Soil to Geosynthetic or Geosynthetic to Geosynthetic Friction by the Direct Shear Method. There …

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GCL shrinkage: A possible solution

February 1, 2009

By Richard Thiel and Chris Thiel Introduction A potential industry-wide concern for GCL shrinkage was identified by Thiel and Richardson (2005) at the January 2005 Geo-Frontiers conference in Austin, Texas, based on observed problems at several sites worldwide. All of the known problems were for installations where an exposed geomembrane/GCL composite installation was left unballasted …

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Slope stability sensitivities of final covers

August 1, 2008

By Richard Thiel Abstract The geotechnical aspects of final cover system slope stability follow the same principles used for other geotechnical stability problems. What is unique and important to recognize, relative to final cover systems, is their sensitivity to relatively small changes in loading, slope angle, pore pressures, or shear strengths that make them more …

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Active LFG control: An unreliable aid to veneer stability

June 1, 2008

By Gregory N. Richardson, Stacey A. Smith, and Pieter K. Scheer Abstract The potential for sliding failure of final covers and piggyback liners in municipal solid waste (MSW) landfills equipped with active landfill gas (LFG) control systems is demonstrated and the need for a contingency passive venting system is presented. Two final cover failures illustrate …

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ASD and LRFD of reinforced SRW with the use of software Program MSEW(3.0)

August 1, 2006

By Dov Leshchinsky Introduction The title of this article contains enough acronyms to confuse even the best engineers. Imagine the confusion when the abbreviations have to be translated into numbers followed by a structure. To alleviate some of the concern, here are the literal conversions: ASD=Allowable Stress Design (e.g., AASHTO 1998, 2002; or NCMA in …

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The enhancement of interface shear strength between two nonwoven geotextiles

April 1, 2006

By Gregory N. Richardson and Pieter K. Scheer Introduction and problem statement Interfaces involving nonwoven to nonwoven geotextile surfaces are sometimes part of the design of landfill liner systems. This is most likely the case in a double-liner system where a geosynthetic clay liner (GCL) is often designed below the upper (primary) geomembrane and is …