Landfill lining engineering designs: a probabilistic approach

Uncertainty and variability are prevalent in any engineering design. In this study, the uncertainty of input parameters for the stability of a landfill veneer cover soil and the integrity of a lining system were treated probabilistically using Monte Carlo simulation. Statistical information required to postulate the distribution types of input parameters, taken as random variables, were identified and characterised using available data from literature survey and a designed laboratory repeatability testing programme. The variability and uncertainty of interface shear strengths (τ) and the derived strength parameters for three generic interfaces, commonly found in a landfill lining system, were computed and compared using these types of information. The variability of τ computed using the combined global database were three-to-five times and could reach up to seven times higher for the derived strength parameters when compared to laboratory repeatability test results. Additionally, a normal distribution was recommended for interface shear strengths and derived parameters (except interface adhesion with high COV) for good quality data based on subjective and objective statistical test methods. [Continues.]