Reliability Model for Soil Liner: Post Construction

Abstract

A methodology is presented for predicting postconstruction reliability of full‐scale soil liners given a set of direct and indirect (compaction moisture content and dry density) permeability measurements from a test fill. The permeability is considered as a spatially correlated, lognormally distributed random variable. Six systems‐reliability measures are defined to characterize a soil liner represented by a system of blocks and lifts. The reliability measures are weakest link, averaging and parallel systems of blocks and lifts. Geostatistics is used to transfer test‐fill information to full‐scale liner permeability/reliability estimates. A relationship is developed for the number of permeability measurements necessary to monitor construction of the full‐scale liner, the target average permeability, and the specified reliability limit. The methodology is illustrated with a numerical example. It is shown how direct permeability measurements and surrogate tests commonly performed during soil‐liner construction can be combined. Reliability bounds, based on effective hydraulic permeability, can be obtained by considering various simple averaging schemes over a multilift soil liner.