Frictional behaviour of three critical geosynthetic interfaces

Abstract

This paper's scope is the shear interaction mechanisms of three critical geosynthetic interfaces (geotextile/geomembrane; drainage geocomposite/geomembrane and soil/geomembrane) typically used for lined containment facilities such as landfills. A large direct shear machine was used to carry out 159 geosynthetic interface tests. The results showed strain softening behaviour, a very small dilatancy, 0.1-1 mm, and non-linear failure envelopes at normal stress range of 25-500 kPa. The three types of interfaces present the same main interaction mechanisms: interlocking and friction. For geotextile/geomembrane and drainage geocomposite/geomembrane interfaces, the higher the asperity height, the higher the interface shear strength. Whereas for soil/geomembrane interfaces, the higher the soil shear strength, the higher the interface shear strength. The drainage geocomposite/geomembrane interface showed the lowest friction angles, followed by the geotextile/geomembrane and the soil/ geomembrane interfaces.

Interface Shear Strengths Between Geosynthetics and Clayey Soils

“…There are three critical geosynthetics and clayey soil interfaces among components of composite linear systems, i.e. GM/clayey soil; GM/GT (GT means geotextile), and GCL/clayey soil [10].…”

Rapid prototyping of geosynthetic interfaces: Investigation of peak strength using direct shear tests

“…As spacing reduced beneath this range, a failure plane was seen to develop across the top of the asperities as indicated in Figure 15. This demonstrates the importance of maintaining sufficient inter-asperity soil friction as described by Bacas et al (2015) rather than simply assuming greater asperity distribution is proportional to shear strength. This optimum spacing reported may be both soil and polymer specific, however, this study provides a valuable insight into the soil -texture interaction, and rapid prototyping allows researchers and manufactures to assess the influence of such variables without costly production modifications.…”

“…The final geometric variable altered for the geomembrane was the asperity height. The expectation is that the greater the asperity height, the greater the interlock at the interface between the geomembrane and geotextile and the higher the peak shear stresses (Bacas, et al, 2015;Ivy, 2003;McCartney et al, 2005). The standard height of 1mm was compared to the minimum GRI requirement of 0.4 mm (Geosynthetics Institute, 2016) (a reduction of 0.6mm) and 1.6mm (an increase of 0.6mm).…”

Modified stress and temperature-controlled direct shear apparatus on soil-geosynthetics interfaces

“…To further investigate the action mechanism of drying-wetting cycles, thermal cycles, and drying-wetting cycles without heating on the creep deformation of the Clay-GDL interfaces, the detailed mechanism analysis was conducted. As shown in Section 5.3, the peak shear strength of clay-GDL interfaces is mobilised from two components: the skin friction and the interlocking effects between soil and GDL (Bacas et al, 2015). The creep shear resistance between soil and GDL can also be attributed to the skin friction and interlocking effects between soil and GDL, as shown in Figure 9.2.…”

“…As shown in Figure 11, the peak shear strength of clay-GDL interfaces is mobilised from two components: the skin friction and the interlocking effects between soil and GDL (Bacas et al, 2015). More specifically, initially, the soil specimen, nonwoven geotextile and drainage core are separate, and after the compaction during the installation of soil, soil penetrates the geotextile and drainage core slightly.…”