Experimental and numerical modeling of thermally-induced ratcheting displacement of geomembranes on slopes

Abstract

Exposed geomembranes are subjected to thermal cycles of relatively high amplitude. In the present study, the behavior of exposed geomembranes on inclined planes subjected to thermal cycles was investigated using experimental and numerical methods. Experimental results corroborated the emergence of thermally-driven displacement accumulation, or ratcheting, which was inversely proportional to the static factor of safety. The complementary numerical study considered the thermo-elastic membrane properties, constant temperature change amplitude, and an elastic-perfectly plastic constitutive model with a critical elastic threshold displacement for the membrane-soil interface. Results show that thermally-induced ratcheting displacements increased as the static factor of safety decreased, in agreement with experimental observations, and as the ratio between the unconstrained thermal elongation of the geomembrane and the critical elastic interface displacement increased.

Thermo-mechanical ratcheting in jointed rock masses

“…Energy conservation and Le Chatelier's principle state that a system in equilibrium could experience a mechanical reaction to oppose an imposed thermal change. This observation anticipatesbut does not explainthermally driven displacements that have been recognised in natural rock slopes (Hatzor, 2003;Watson et al, 2004;Gunzburger et al, 2005;Gischig et al, 2011;Bakun-Mazor et al, 2013;Pasten, 2013;Greif et al, 2014) and engineered systems such as pavement structures, exposed geomembranes and thermo-active piles (Croll, 2009;Pasten & Santamarina, 2014a, 2014b.…”

Experimental and Numerical Studies on Thermally-Induced Slip Ratcheting on a Slope

“…Those temperature effects are relatively well-studied, but recently, some other cases were reported, which indicate moderately mild temperature change still could induce structural failure of the system-a slip accumulation (or allegedly "slip ratcheting") over the interface between dissimilar materials accompanied with gravity. Examples of cyclic temperature and the corresponding displacement buildup of geotechnical systems are found in a variety of geotechnical problems, such as movements of natural rock slopes [1][2][3], exposed geosynthetic liners [4], pavement layers [5], and geothermal energy piles [6,7].…”