Discussion of “Analysis of a Large Database of GCL Internal Shear Strength Results” by Jorge G. Zornberg, John S. McCartney, and Robert H. Swan, Jr.

Abstract

The discusser cites Chiu and Fox (2004) regarding a large published database containing analysis of internal and interface geosynthetic clay liners (GCL) shear strengths, including those of the discusser. One item found in this database conflicts with the authors' results ? the failure envelope. For hydrated needle-punched GCLs, the non-linear regression analysis produced a zero intercept instead of the permitted non-zero intercept. This contradicts the authors' test results. In shear-induced excess pore pressures, the discusser states that the hypothesis of the authors -- that pore water suction causes progressively larger shear strengths with increasing shear displacement rate (SDR) at low normal stresses -- is not borne out in the data from Fox et al. (1998). As for SDR effects at high normal stress conditions, the discusser notes that more research is needed.