Shear Strength Characteristics of PVC Geomembrane-Geosynthetic Interfaces

Abstract

Torsional ring shear and large-scale direct shear tests were conducted to investigate the shear behavior of polyvinyl chloride (PVC) geomembrane-geosynthetic interfaces. Specifically, the smooth and faille-finished sides of a 0.75 mm-thick PVC geomembrane were sheared against five different nonwoven geotextiles, a drainage composite, a geonet, and an unreinforced geosynthetic clay liner (GCL). Test results indicate that the smooth side of the PVC geomembrane yields a higher interface shear resistance than the faille-finished side due to the larger contact area and higher pliability of the smooth side. The interface shear behavior of the PVC geomembrane is compared to that of a high density polyethylene (HDPE) geomembrane and two very flexible polyethylene (VFPE) geomembranes. Faille-finished PVC geomembrane-nonwoven geotextile interfaces experience a post-peak strength loss of less than 25% at normal stresses between 100 and 400 kPa and no post-peak strength loss at normal stresses of 50 kPa and below. This behavior is attributed to the pliability of the PVC geomembrane, which enables (i) the geomembrane surface to be roughened, (ii) the other interface component to embed into the geomembrane as shearing progresses, and (iii) no texturing to be used that can damage the overlying geosynthetic. The effects of nonwoven geotextile fiber type, mass per unit area, and calendering on PVC geomembrane-nonwoven geotextile interface strength are also investigated.

Base sliding and dynamic response of landfills

“…The values obtained, 10.5-12.5°, agree with those reported (10.7-11.3°) by Yegian and Lahlaf [25] and with the ones reported by Hillman and Stark [26] for similar geosynthetics. However, both material type and texturing of geomembranes affect the interface shear strength, while the mass per unit area, calendering, polymer material and fiber type of the geotextile were also found important, resulting to a wider range (7-32°) of proposed angles of friction [26,27]. Finally, sand to geotextile interfaces exhibit failure envelopes similar to the corresponding of the sand material, while the texturing of the geotextile affects the resulting values in a minor extent [28].…”

Plasticizer Retention in PVC Geomembranes

“…Flexible PVC geomembranes have several advantages over other geomembranes. The advantages include greater flexibility that results in better resistance to differential settlement and puncture, significantly less field seams because it can be factory fabricated into large panels, the field seams can be formed using single or dual-track wedge-welding equipment, use of typical construction quality assurance (CQA) and construction quality control (CQC) procedures, if air channel testing of dual-track wedge-welding is used destructive seam testing can be reduced or eliminated (Stark et al 2004;Thomas et al 2003), smaller geomembrane wrinkles because of high interface strength and a low coefficient of thermal expansion, a larger allowable tensile strain, the lack of a yield point even at low temperatures, and high interface shear resistance (Hillman and Stark 2001) for slope stability.…”

Beneficial Use of Shredded Tires as Drainage Material in Cover Systems for Abandoned Landfills

“…The friction angles were measured with a best-fit line through the origin and the data. These interface friction angles are significantly higher than those usually measured for geosynthetic interfaces typically found in geosynthetic landfill final cover systems ͑Hillman and Stark 2001͒. The failure envelopes in Fig. 8 are applicable to a landfill final cover system and not a liner system.…”