Reinforced Soil Structures with Poorly Draining Backfills Part II: Case Histories and Applications

Experimental studies on poorly draining soil-reinforcement interactions were reviewed in a companion paper by Zornberg and Mitchell in 1994, leading to the conclusion that permeable geosynthetic inclusions are useful for reinforcing marginal backfills. This conclusion is strengthened by lessons learned from the case histories described in this paper. There are no design guidelines for reinforced soil structures using poorly draining backfills. Nevertheless, several of these structures have already been constructed, and the performance of some of them has been reported. Good structure performance is strongly dependent on maintaining a low water content in the poorly draining fill. Large movements occurred in reinforced structures when pore water pressures were generated, and failures were reported in marginal backfills reinforced with impermeable inclusions that became saturated after rainfalls. Benefits and applications of reinforcing poorly draining backfills are addressed, and research needs aimed at formulating a consistent design methodology for these structures are presented.