Experimental study and numerical modelling on creep and creep recovery characteristics of geomembrane

The creep and creep recovery of HDPE geomembrane with three different thicknesses under six different load levels are investigated. The creep and creep recovery characteristics of the geomembrane and their influencing factors are deeply analyzed. The test results show that the geomembrane deforms instantly when the load is applied and removed, and then the deformation rate gradually slows down with time. When the load level is lower than 30%, the deformation of the geomembrane tends to be stable with time. When the load level is higher than 40%~50%, the strain of the geomembrane increases at a constant rate in the second stage creep. When the applied load level exceeds 20%, the geomembrane will produce residual deformation after creep recovery and complete unloading, and the residual deformation will increase approximately linearly with the increase of load level. The initial modulus of the geomembrane is influenced by both the load level and the creep process. When the load level of the geomembrane rises to 40%~50%, its initial modulus will drop significantly by more than 100 MPa. In addition, a composite element model for the creep and creep recovery of geomembrane considering the viscoelastic properties of materials is established. The numerical simulation shows that the proposed model can well reflect the creep and creep recovery process of the geomembrane under different load levels.