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

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 (φ_in) between GM-GT were firstly determined at the normal stresses (σ_n) of 25, 50, 100 and 200 kPa. The results show that TGM-NWGT has a much larger φ_in (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 (τ_p) 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 (δ_cp). The coefficients A and B in the power equation were found to be functions of Young's modulus of the composite material (E_c), time, σ_n, τ, τ_p, and φ_in. 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.