Abstract
As a type of flexible impermeable material, a PVC geomembrane must be cooperatively used with cushion materials. The contact interface between a PVC geomembrane and cushion easily loses stability. In this present paper, we analyzed the shear models and parameters of the interface to study the stability. Two different cushion materials were used: the common extrusion sidewall and non-fines concrete. To simulate real working conditions, flexible silicone cushions were added under the loading plates to simulate hydraulic pressure loading, and the loading effect of flexible silicone cushions was demonstrated by measuring the actual contact areas under different normal pressures between the geomembrane and cushion using the thin-film pressure sensor. According to elastomer shear stress, there are two main types of shear stress between the PVC geomembrane and the cushion: viscous shear stress and hysteresis shear stress. The viscous shear stress between the geomembrane and the cement grout was measured using a dry, smooth concrete sample, then the precise formula parameters of the viscous shear stress and viscous friction coefficient were obtained. The hysteresis shear stress between the geomembrane and the cushion was calculated by subtracting the viscous shear stress from the total shear stress. The formula parameters of the hysteresis shear stress and hysteresis friction coefficient were calculated. The three-dimensional box-counting dimensions of the cushion surface were calculated, and the formula parameters of the hysteresis friction were positively correlated with the three-dimensional box dimensions.
Highlights
As a type of flexible impermeable material, a PVC geomembrane must form an impermeable structure with cushion materials to play an impermeable role
The thin-film pressure sensor is a new type of plane stress measurement instrument that can directly measure the stress on the sensor surface
Common extrusion sidewall and non-fines concrete cushion materials were selected for the study of PVC geomembrane-cushion interface stability
Summary
As a type of flexible impermeable material, a PVC geomembrane must form an impermeable structure with cushion materials to play an impermeable role. Girard et al analyzed the instability of the interface between the geotechnical cloth and the geomembrane in an embankment project Through analysis, they found that the main cause of this event was overestimation of the interfacial shear strength [1]. Dixon et al noted that the corresponding calculation formula for geosynthetics obtained through experiments did not fully coincide with the actual project, and they suggested that the design guidance should be proposed by performing and summing error analyses of the test data [4]. Wu proposed the mechanical models of different shear stages by analyzing the characteristics of the geosynthetic interfacial shear and suggested using different shear strengths in different areas of a project through the LEM and flac3d simulation [16]. Based on the elastomer friction, this paper analyzed the components and characteristics of the geomembrane shearing phenomenon
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