Containment Lining
The liner does not fail under the water. It fails on the one stone the cushion was too light to bridge.
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Liner puncture resistance divided by the cushioned point force
Index puncture resistance from a laboratory probe is not the same quantity as long-term field puncture under sustained load, and the gap between them is why real designs apply creep and chemical-degradation reduction factors on top of the safety factor computed here. The protection factor is a linear fit and will overstate very heavy cushions, which stop improving once the geotextile itself begins to bridge rather than compress. Containment liner design is regulated work — treat this as a screening check, not a specification.
Geomembrane Puncture Resistance under Hydrostatic Load — free, with the formula and a worked example, at Textile School.