Characterisation of geomembrane and geotextile interface short-term creep behaviour in a dry condition

Abstract

This study aims to characterise the interface creep behaviour between geomembrane and geotextile (i.e. GM-GT) in the liner system. Two types of GM (i.e. smooth SGM and textured TGM) and two types of GT (i.e. nonwoven NWGT and woven WGT) were investigated using the conventional direct shear apparatus for four combinations of GM-GT. The interface friction angles (φin) between GM-GT were firstly determined at the normal stresses (σn) of 25, 50, 100 and 200 kPa. The results show that TGM-NWGT has a much larger φin (23.9°) than the other three combinations which ranged from 9.5° to 11.1°. Subsequently, creep tests were conducted at three shear stress (τ) levels (i.e., 30, 50 and 70% of the peak stress (τp) under each normal stress). The creep test results of the four combinations were analysed and a power equation of time was used to estimate creep displacement (δcp). The coefficients A and B in the power equation were found to be functions of Young's modulus of the composite material (Ec), time, σn, τ, τp, and φin. The tertiary creep stage was not observed in the test and it is recommended that longer duration GM-GT interface creep tests should be conducted for in-depth understanding of the interface creep mechanism.