Interface shear creep behavior between the nonwoven geotextile and the geomembrane pre/post peak strength

In landfills, shear creep of the liner interface occurs after some shear displacements under the influence of a sustained load from waste. In this paper, an apparatus was developed to conduct shear creep tests on interfaces after different initial shear displacements, and experimental investigations were performed on the shear creep behavior of the geotextile and geomembrane interfaces pre/post peak strength. The results demonstrated that the initial instantaneous displacement and the steady displacement rate at the interface increased with increasing shear stress. The initial instantaneous displacement at the geomembrane‒geotextile interface in the post-peak tests was reduced compared with that in the pre-peak tests, whereas the displacement rate at elevated shear stress levels was greater in the post-peak tests than in the pre-peak tests. The creep behavior of the interface was influenced by both the initial shear displacement and the material interaction. An analysis of the Nishihara model revealed that the shear modulus of the Hooke body at the interface increased with increasing shear stress in the pre-peak test, whereas it decreased in the post-peak test as the shear stress increased. The difference in calculated creep time from the 30-day test results and from 3-day creep test results was approximately 8.9%.