Design of exposed geomembrane-lined ponds

摘要

Part 1 of this series in the October/November 2017 issue of Geosynthetics demonstrated how the size, shape, pressure, and stresses and strains experienced by geomembrane bubbles surrounded by a confining fluid could be analytically estimated. Two different field case histories exhibiting the extremes of bubble sizes in ponds lined with 60-mil (1.5-mm) high-density polyethylene (HDPE) geomembranes were shown to corroborate the bubble sizes and pond depths estimated by the suggested analytical approach. Starting with an observed diameter of a bubble at the water surface and an assumed state of stress-strain in the geomembrane, Part 1 presented equations to estimate the depth of water surrounding the bubble that would exert hydrostatic pressures on the outside of the bubble to balance the calculated internal pressure needed to develop the assumed stress-strain state in the bubble. The method also predicts the bell-shaped profile of the entire bubble shape. This article, Part 2 of this series, discusses the often-used engineering approach of providing a gas-venting layer below the geomembrane to solve the bubble issue.